Battery module, battery pack, and vehicle with such batteries mounted thereon

The present invention relates to a battery module formed by stacking bipolar batteries, an assembled battery formed by electrically connecting a plurality of battery modules, and a vehicle equipped with these batteries.

In recent years, there has been an urgent need to reduce carbon dioxide emissions for environmental protection. In the automobile industry, expectations are high for the reduction of carbon dioxide emissions by introducing electric vehicles (EVs) and hybrid electric vehicles (HEVs), and the development of secondary batteries for driving motors, which holds the key to their practical application, is enthusiastic. It is done. As a secondary battery, as shown in Patent Document 1, attention is focused on a laminated bipolar battery capable of achieving high energy density and high output density.

In a general bipolar battery, a plurality of bipolar electrodes are connected in series with an electrolyte layer interposed therebetween, that is, a laminated battery element, an exterior material that wraps and seals the entire battery element, and an exterior for extracting electric current. Includes terminals derived from the material to the outside. In the bipolar electrode, a positive electrode active material layer is provided on one surface of the current collector to form a positive electrode, and a negative electrode active material layer is provided on the other surface to form a negative electrode. The positive electrode active material layer, the electrolyte layer, and the negative electrode active material layer are laminated in this order to form a cell cell layer, and the cell cell layer is sandwiched between a pair of current collectors. The bipolar battery has an advantage that the current path is short and the current loss is small because the current flows in the battery element in the direction in which the bipolar electrodes are laminated, that is, in the thickness direction of the battery.

In order to obtain the required capacity and voltage, a plurality of bipolar batteries may be electrically connected to form a battery module, or a plurality of battery modules may be electrically connected to form an assembled battery. ing. The battery module is a kind of assembled battery in that it includes a plurality of electrically connected bipolar batteries, but in the present specification, the unit unit for assembling the "assembled battery" is referred to as a "battery module". It will be referred to.

When forming the battery module, it is necessary to seal the battery element with the exterior material in advance, and it is not possible to simplify a series of operations for forming the battery module.

Further, in order to electrically connect a plurality of bipolar batteries, it is necessary to join the terminals led out from the exterior material to the outside by welding or to connect them via a connecting member such as a bus bar. However, also from this point of view, it is not possible to simplify a series of operations for forming the battery module.

Further, when the battery module is mounted on a vehicle such as an automobile or a train, there arises a problem that the long-term reliability of the battery module is lowered as compared with the case where the battery module is used in a stationary state.

Therefore, as a result of diligent studies, we have found that the following causes the deterioration of the long-term reliability of the battery module. That is, when vibration from the road surface or a power source is applied to the battery module and transmitted to the inside of the battery, the electron conduction path inside the bipolar battery is disconnected, which reduces the long-term reliability of the battery module.

In order to solve this problem, as described in Patent Document 2, a flat battery capable of extracting current from both sides in the stacking direction of the power generation element and the current extraction surface of the flat battery are in surface contact with each other. We have proposed a battery module in which a flat plate-shaped electrode tab for taking out an electric current and an outer case for covering the flat battery and the electrode tab are provided, and an elastic body is interposed between the inner surface of the outer case and the electrode tab.

However, when an elastic body is installed between the inner surface of the outer case and the electrode tab, if a thick and rigid electrode tab is used for the bipolar battery, not only the vibration entering from the battery exterior but also the vibration entering from the electrode tab is large. Affect. Therefore, it is necessary to further improve the vibration resistance performance invading from the electrode tab while simplifying a series of operations for forming the battery module, and further studies have been carried out to propose the present invention.<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2001-236946</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2002-110239</text></patcit>

<p> The present invention provides a battery module that can be easily manufactured by simplifying a series of manufacturing operations, a low-cost assembled battery formed by electrically connecting a plurality of the battery modules, and a vehicle equipped with the batteries. With the goal.</p><p> Furthermore, an object of the present invention is to provide a battery module having further improved vibration resistance, a low-cost assembled battery formed by electrically connecting a plurality of the battery modules, and a vehicle equipped with these batteries. ..</p>

<p> The invention according to claim 1 for achieving the above object is a flat battery capable of extracting current from both sides in the stacking direction of power generation elements, and a flat battery that comes into surface contact with the current extraction surface of the flat battery. A flat plate-shaped electrode tab for taking out current and an outer case covering the flat battery and the electrode tab are provided, and at least one electron conductivity is provided between the flat battery and the electrode tab, or between the flat batteries. It is a battery module characterized in that an elastic body having the above is interposed.</p>

<p> According to the battery module of the present invention, at least one elastic body is interposed between the flat battery and the electrode tab, or between the flat batteries, so that the flat battery and the electrode tab are contained in the outer case. The electrode tab is pressed against the current extraction surface of the flat battery by the elastic force of the elastic body simply by inserting an elastic body having electron conductivity between the flat batteries. The element is pressed. Therefore, the batteries constituting the power generation element can be brought into surface contact with each other and electrically connected to each other, and there is no need to lead out terminals from the exterior material to the outside, and there is no need for work such as welding and joining the terminals. A battery module can be easily manufactured by simplifying a series of manufacturing operations.</p><p> Further, since an elastic body having at least one electron conductivity is interposed between the flat battery and the electrode tab, or between the flat batteries, the flat battery has at least one electron conductivity. It is held by the elastic body, and the vibration transmitted to the battery module can be reduced by the elastic body having electronic conductivity, and the long-term reliability of the battery module can be ensured.</p>

Hereinafter, embodiments of a battery module, an assembled battery, and a vehicle equipped with these batteries according to the present invention will be described in detail with reference to the drawings. In the drawings cited in the following embodiments, the thickness and shape of each layer constituting the battery are exaggerated, but this is done to facilitate understanding of the content of the invention. , It does not match the thickness and shape of each layer of the actual battery.

(First Embodiment) FIGS. 1 (A) and 1 (B) are schematic configuration diagrams of a conventional battery module described in Japanese Patent Application Laid-Open No. 2002-110239, and FIGS. 2 (A) and 2 (B) are. , FIGS. 3 (A) and 3 (B) show a schematic configuration diagram of a battery module according to the present invention having a structure in which an elastic body having electron conductivity is interposed between a flat battery and a positive electrode tab. A schematic configuration diagram of a battery module according to the present invention, which has a structure in which an elastic body having electron conductivity is interposed between a flat battery and a positive electrode tab and between a flat battery and a negative electrode tab. 4 (A) and 4 (B) are schematic configuration views and diagrams of a battery module according to the present invention having a structure in which an elastic body having electron conductivity is interposed between two laminated flat batteries. 5 (A) and (B) have electron conductivity between the flat battery and the positive electrode tab, between the flat battery and the negative electrode tab, and between the two stacked flat batteries. It is a schematic block diagram of the battery module which concerns on this invention which has the structure in which an elastic body is interposed.

The battery module according to the present invention includes a flat battery capable of extracting current from both sides in the stacking direction of power generation elements, and a flat plate-shaped positive electrode capable of extracting current by surface contact with the current extraction surface of the flat battery. It includes a negative electrode tab and an exterior case (not shown) that covers the flat battery and the electrode tab, and as shown in FIGS. 2 (A) to 5 (B), the flat battery and the electrode tab. An elastic body having at least one electron conductivity is interposed between the batteries and the batteries.

Based on the diagrams shown in FIGS. 1 (A) to 5 (B), the principle that the battery module according to the present invention has vibration resistance will be described in detail in comparison with the conventional battery module.

FIG. 1A is a diagram schematically showing the battery module of Patent Document 2 introduced in the column of the prior art. Unlike the battery module of the present invention, this battery module is provided with an elastic body between the battery modules. The flat battery 1 in the figure is a portion generally referred to as a power generation element, and is a portion in which a plurality of positive electrode layers, separators, and negative electrode layers are laminated in this order. In the battery module of Patent Document 2, a positive electrode tab 2 and a negative electrode tab 3 are attached to the upper and lower ends of the flat battery 1 in the stacking direction. Further, an elastic body 4a and an elastic body 5a for absorbing vibration are attached to the positive electrode tab 2 and the negative electrode tab 3 in close contact with each other on the outside of the positive electrode tab 2 and the negative electrode tab 3 in the stacking direction.

FIG. 1 (B) is a diagram showing a vibration model of the battery module shown in FIG. 1 (A). Since the flat battery 1 has a configuration in which the upper and lower ends of the stacking direction are sandwiched by the elastic body 4a and the elastic body 5a that function as springs, the magnitude of the vibration is slightly small when vibration is applied to the battery module. Although it is reduced, the reduced vibration is applied to the flat battery 1 as it is, so the vibration reduction effect cannot be said to be so great. In particular, when vibration is directly applied from the positive electrode tab 2 and the negative electrode tab 3, the vibration is directly transmitted to the flat plate battery 1, so that there is almost no vibration reducing effect.

FIG. 2A shows a battery module according to the present invention, in which an elastic body 4b having electron conductivity is interposed between a flat battery 1 and a positive electrode tab 2. .. The elastic body 4b having electron conductivity needs to have conductivity because it must have a function of passing a current from the flat battery 1 to the positive electrode tab 2.

Therefore, it is desirable that the elastic body 4b having electron conductivity is formed of a polymer material having conductivity, and the polymer material itself is a conductive polymer having conductivity (see FIG. 28 (A)). As the conductive polymer, polyaniline, polypyrrole, polythiophene, polyacetylene, polyparaphenylene, polyphenylene vinylene, polyacrylonitrile, and polyoxadiazol can be used. Further, the elastic body 4b having electron conductivity is formed of a polymer material having conductivity, and the polymer material having the conductivity is composed of a polymer material and a conductive filler for adding conductivity. (See Fig. 28 (B)). As the polymer material, polyolefin (polypropylene, polyethylene), polyester (PET, PEN), polyimide, polyamide, polyvinylidene fluoride (PVdF), epoxy resin or synthetic rubber material can be used. Further, as the conductive filler, preferably, Ag fine particles, Au fine particles, Cu fine particles, Al metal fine particles, SUS fine particles, Ti fine particles can be used, and more preferably carbon fine particles can be used. In addition, these conductive fillers may be those in which a conductive material is coated around a particle-based ceramic material or a resin material by plating or the like. Further, the elastic body 4b having electron conductivity may be formed of a non-woven fabric or woven fabric having conductivity.

Further, since the elastic body 4b having electron conductivity must have a function as a cushion for absorbing the vibration applied to the battery module, the elastic body 4b having electron conductivity is the smallest of the flat battery 1. It has an elastic force that can apply pressure to the contact portion between the positive electrode tab 2 and the flat battery 1 during contraction. Further, the elastic body 4b having electron conductivity has a thickness capable of absorbing the thermal expansion of the flat battery 1, so that the shrinkage of the flat battery 1 at the time of charging and discharging can be absorbed. Further, the elastic body 4b having electron conductivity has a friction coefficient in which the flat battery 1 cannot move when the repeated stress acts. Furthermore, the Young's modulus of the elastic body 4b having electron conductivity is 0.01 to 0.30 × 10.¹⁰N / m²Is in the range of. When the Young's modulus of the elastic body 4b having electron conductivity is within this value range, when the battery module is mounted on the vehicle, the resonance frequency of the battery module is shifted from the resonance frequency of the vehicle (100 Hz or less) to the high frequency side. be able to. Due to this effect, as long as the battery module is used in the vehicle, the battery module can be used in the region of the vibration frequency deviating from the resonance frequency, so that the battery module has a high vibration isolation effect.

FIG. 2B is a diagram showing a vibration model of the battery module shown in FIG. 2A. The flat battery 1 has a configuration in which an elastic body 4b having electronic conductivity that functions as a spring is sandwiched between the flat plate battery 1 and the positive electrode tab 2, so that when vibration is applied to the battery module 1. , The magnitude of vibration transmitted from the positive electrode tab 2 to the flat plate battery 1 is considerably reduced. Therefore, the effect of reducing the vibration transmitted from the positive electrode tab 2 to the flat plate battery 1 is greater than that of the conventional battery module shown in FIG. 1 (A).

FIG. 3A shows a battery module according to the present invention, in which an elastic body 4b having electron conductivity between the flat battery 1 and the positive electrode tab 2 is provided in the flat battery 1. An elastic body 5b having electron conductivity is interposed between the negative electrode electrode tab 3 and the negative electrode tab 3. The electronically conductive elastic body 4b must have a function of passing an electric current from the flat battery 1 to the positive electrode tab 2, and the electronically conductive elastic body 5b also has a function of passing an electric current from the flat cell 1 to the positive electrode tab 2. Since the negative electrode tab 3 must have a function of passing an electric current, the elastic body 4b having electron conductivity and the elastic body 5b having electron conductivity need to have conductivity. The materials, elastic forces, and Young's modulus constituting the elastic body 4b having electron conductivity and the elastic body 5b having electron conductivity are the same as those described above.

FIG. 3B is a diagram showing a vibration model of the battery module shown in FIG. 3A. In the flat battery 1, the elastic body 4b having electronic conductivity that functions as a spring is sandwiched between the flat plate battery 1 and the positive electrode tab 2, and the elastic body 5b having electronic conductivity is sandwiched between the flat plate battery 1 and the negative electrode tab 3. When vibration is applied to the battery module 1, the magnitude of the vibration transmitted from the positive electrode tab 2 and the negative electrode tab 3 to the flat plate battery 1 is shown in FIG. 2 (A). It is further reduced compared to the battery module of the above configuration. Therefore, the effect of reducing the vibration transmitted from the positive electrode tab 2 to the flat plate battery 1 is much larger than that of the conventional battery module shown in FIG. 1 (A).

FIG. 4A shows a battery module according to the present invention, in which an elastic body 4b having electronic conductivity is interposed between two stacked flat batteries 1. Since the elastic body 4b having electron conductivity must have a function of passing an electric current between the flat batteries 1, the elastic body 4b having electron conductivity needs to have conductivity. The materials, elastic forces, and Young's modulus constituting the elastic body 4b having electron conductivity and the elastic body 5b having electron conductivity are the same as those described above.

FIG. 4B is a diagram showing a vibration model of the battery module shown in FIG. 4A. Since the flat battery 1 has a configuration in which an elastic body 4b having electronic conductivity that functions as a spring is sandwiched between the flat plate battery 1 and the flat plate battery 1, vibration is applied to one of the battery modules 1. In this case, the magnitude of the vibration transmitted to the other flat plate battery 1 is reduced as compared with the battery module having the configuration shown in FIG. 2 (A).

FIG. 5A shows a battery module according to the present invention, in which the flat battery 1 has an elastic body 4b having electron conductivity between the flat battery 1 and the positive electrode tab 2. An elastic body 5b having electron conductivity is interposed between the flat battery and the flat battery, and an elastic body 6 having electron conductivity is interposed between the flat battery 1 and the negative electrode tab 3. The electronically conductive elastic body 4b must have a function of passing an electric current from the flat battery 1 to the positive electrode tab 2, and the electronically conductive elastic body 5b is also between the flat batteries 1. Since the elastic body 6 having electron conductivity must also have a function of passing an electric current from the flat cell 1 to the negative electrode tab 3, it must have a function of passing an electric current. The elastic body 4b having electron conductivity, the elastic body 5b having electron conductivity, and the elastic body 6 having electron conductivity need to have conductivity. The materials, elastic forces, and Young's modulus constituting the elastic body 4b having electron conductivity, the elastic body 5b having electron conductivity, and the elastic body 6 having electron conductivity are the same as those described above.

FIG. 5 (B) is a diagram showing a vibration model of the battery module shown in FIG. 5 (A). In the flat battery 1, the elastic body 4b having electron conductivity that functions as a spring is formed by the flat plate battery 1 and the positive electrode tab 2, and the elastic body 5b having electronic conductivity is formed by the flat plate battery 1 and the flat plate battery 1. Since the conductive elastic body 6 is sandwiched between the flat plate battery 1 and the negative electrode tab 3, when vibration is applied to the battery module 1, the positive electrode tab 2 and the negative electrode tab 3 are used. The magnitude of the vibration transmitted to the flat plate battery 1 is further reduced as compared with the battery module having the configuration shown in FIG. 2A introduced in the above embodiment. Therefore, the effect of reducing the vibration transmitted from the positive electrode tab 2 to the flat plate battery 1 is much larger than that of the conventional battery module shown in FIG. 1 (A).

(Second Embodiment) FIG. 6 is a cross-sectional view showing a laminated structure of the battery modules 11 according to the second embodiment of the present invention, and FIG. 7 is a cross-sectional view showing a bipolar battery 40 shown in FIG. 8 is a cross-sectional view showing the bipolar electrode 21, and FIG. 9 is a cross-sectional view for explaining the cell cell layer 26. FIG. 10 is a diagram showing a stepwise state of the manufacturing process of the electrolyte layer 25 in which the seal portion 30 is formed on the separator 25a, and FIG. 10 (A) is a schematic diagram showing the separator 25a forming the base material of the electrolyte layer 25. A plan view, FIG. 10 (B) is a schematic plan view showing a state in which the seal portion 30 is formed on the outer peripheral portion of the separator 25a, and FIG. 10 (C) shows the electrolyte portion 25b inside the seal portion 30 of the separator 25a. A schematic plan view showing a state in which the electrolyte layer 25 is formed and the electrolyte layer 25 is completed, FIG. 10 (D) is a cross-sectional view taken along the line 5D-5D of FIG. 10 (C). FIG. 11 (A) is a cross-sectional view of a main part showing a state in which the electrolyte layer 25 in which the seal portion 30 is formed on the separator 25a and the bipolar electrode 21 are laminated, and FIG. 11 (B) shows the electrolyte layer 25 and the bipolar electrode 21. It is sectional drawing which shows the state which presses the battery element 20 which laminated with and from both sides along the stacking direction, and a seal part 30 is brought into close contact with a current collector 22.

In the second embodiment, in the battery module 11, a plurality of bipolar batteries 40 are laminated in the direction in which the bipolar electrodes 21 are laminated (vertical direction in FIG. 1), and in the illustrated example, for example, four bipolar batteries 40 are electrically connected. Are connected in series. This electrical connection form is called "4 series". The bipolar battery 40 has a rectangular flat shape (flat shape) (see FIG. 12), and on both sides of the four series flat batteries, a flat plate shape for drawing current to the current take-out surface. The positive electrode tab 50 and the negative electrode tab 60 of the above are arranged so as to be in surface contact with each other. The positive electrode tab 50 and the negative electrode tab 60 are formed of a conductive metal plate such as copper, aluminum, and stainless steel, and in FIG. 1, the positive electrode tab 50 shown on the upper side is electrically connected to the positive electrode side of the uppermost bipolar battery 40. The negative electrode tab 60, which is connected and shown on the lower side, is electrically connected to the negative electrode side of the lowest bipolar battery 40. The battery module 11 in the illustrated example is provided with four series of bipolar batteries 40, but the number of layers can be arbitrarily selected.

In the following description, the direction in which the bipolar electrodes 21 are laminated, that is, the thickness direction of the battery is referred to as the "stacking direction", and the direction orthogonal to the stacking direction, that is, the direction in which the current collector 22 or the like extends is the "plane direction". That is. Further, the positive electrode tab 50 and the negative electrode tab 60 are also collectively referred to as an electrode tab, if necessary.

In the bipolar electrode 21, as shown in FIG. 8, a positive electrode active material layer 23 is arranged on one surface of the current collector 22 to form a positive electrode, and a negative electrode active material layer 24 is arranged on the other surface to form a negative electrode. Is formed. The positive electrode terminal electrode of the battery element 20 is provided with only the positive electrode active material layer 23 on one surface of the current collector 22, and is laminated on the uppermost bipolar electrode 21 in FIG. 7 via the electrolyte layer 25. The negative electrode terminal electrode of the battery element 20 is provided with only the negative electrode active material layer 24 on one surface of the current collector 22, and is laminated under the lowermost bipolar electrode 21 in FIG. 7 via the electrolyte layer 25. The positive electrode terminal electrode and the negative electrode terminal electrode are also a type of bipolar electrode 21. The electrolyte layer 25 is configured by holding the electrolyte in a separator 25a (see FIG. 10 (A)) forming a base material.

As shown in FIG. 9, the cell cell layer 26 is formed by laminating a positive electrode active material layer 23, an electrolyte layer 25, and a negative electrode active material layer 24. The cell cell layer 26 is sandwiched between adjacent current collectors 22 in the battery element 20 in which the bipolar electrodes 21 are laminated. The bipolar battery 40 in the illustrated example is provided with a 5-layer single battery layer 26, but the number of layers can be arbitrarily selected. The thickness of the bipolar battery 40 including the five-layer single battery layer 26 is, for example, about 500 μm to 600 μm.

The seal portion 30 blocks the contact between the cell cell layer 26 and the outside air. This prevents liquid leakage due to liquid leakage, which may occur when a liquid or semi-solid gel-like electrolyte is used. It also prevents the air or the moisture contained in the air from reacting with the active material. The seal portion 30 of the present embodiment is formed on the outer peripheral portion of the separator 25a of the electrolyte layer 25 (see FIG. 10 (D)). The electrolyte layer 25 including the sealing portion 30 is roughly manufactured as follows.

First, as the base material of the electrolyte layer 25, a separator 25a corresponding to the size used for the electrolyte layer 25 is prepared (see FIG. 10 (A)). Next, a sealing resin 30a (solution) is placed on the outer peripheral portion of the separator 25a to form the sealing portion 30 (see FIG. 10 (B)). The outer peripheral portion of the separator 25a means the outer side of the portion where the electrolyte is held by the separator 25a. The sealing resin 30a is arranged on the outer peripheral portion of the separator 25a, for example, by filling / injecting, coating or impregnating with a mold having an appropriate shape. The seal portion 30 is formed on both the front and back surfaces of the separator 25a. The thickness (height) of the sealing portion 30 protruding from both the front and back surfaces of the separator 25a is set to be thicker than the thickness of the positive electrode and the thickness of the negative electrode. Next, the electrolyte is held by the separator 25a inside the seal portion 30 to form the electrolyte portion 25b (see FIGS. 10 (C) and 10 (D)). The electrolyte portion 25b is formed by an appropriate method such as a method of applying and impregnating an electrolyte raw material slurry for physical cross-linking, or a method of further polymerizing and chemically cross-linking. As described above, the electrolyte layer has a structure in which the electrolyte is held by the separator 25a, and the sealing resin 30a forming the sealing portion 30 is arranged on the portion of the separator 25a holding the electrolyte, that is, the outer peripheral portion of the electrolyte portion 25b. 25 can be manufactured.

As the separator 25a, either a microporous membrane separator or a non-woven fabric separator can be used.

As the microporous membrane separator, for example, a porous sheet made of a polymer that absorbs and retains an electrolyte can be used. Examples of the polymer material include polyethylene (PE), polypropylene (PP), a laminate having a three-layer structure of PP / PE / PP, and polyimide.

As the non-woven fabric separator, for example, a sheet made by entwining fibers can be used. Further, a spun bond obtained by fusing the fibers to each other by heating can also be used. That is, it may be a sheet-like material obtained by arranging the fibers in a web (thin cotton) shape or a mat shape by an appropriate method and joining them with an appropriate adhesive or the fusion force of the fibers themselves. The fiber to be used is not particularly limited, and for example, conventionally known fibers such as polyolefins such as cotton, rayon, acetate, nylon, polyester, polypropylene and polyethylene, polyimide and aramid can be used. These are used alone or in combination depending on the purpose of use (mechanical strength required for the electrolyte layer 25, etc.).

The shape of the sealing resin 30a arranged on the outer peripheral portion of the separator 25a is not particularly limited as long as it can effectively exhibit the effect of sealing the cell layer 26. For example, in addition to the rectangular cross section shown in FIG. 10 (D), the resin 30a for sealing can be arranged so as to have a semicircular cross section or an elliptical cross section.

It is desirable that the sealing portion 30 obtained by arranging the sealing resin 30a penetrates the separator 25a or covers the entire side surface of the separator 25a. This is because the contact between the cell cell layer 26 and the outside air can be reliably blocked through the inside of the separator 25a.

The sealing resin 30a includes a rubber resin that adheres to the current collector 22 by being deformed by pressure, or an olefin resin that adheres to the current collector 22 by heat-pressing and heat-sealing. A wearable resin can be preferably used.

In the illustrated example, a rubber-based resin is used as the sealing resin 30a. In the rubber-based seal portion 30 using the rubber-based resin, the contact between the cell cell layer 26 and the outside air can be blocked by utilizing the elasticity of the rubber-based resin. Further, even in an environment where stress due to vibration or impact repeatedly acts on the bipolar battery 40, the rubber-based seal portion 30 easily twists or deforms following the twist or deformation of the bipolar battery 40, so that the sealing effect is obtained. Can be retained. Further, it is not necessary to perform the heat fusion treatment, which is advantageous in that the battery manufacturing process is simplified. The rubber-based resin is not particularly limited, but is preferably a rubber-based resin selected from the group consisting of silicon-based rubber, fluorine-based rubber, olefin-based rubber, and nitrile-based rubber. These rubber-based resins have excellent sealing properties, alkali resistance, chemical resistance, durability / weather resistance, heat resistance, etc., and these excellent performances and qualities should be maintained for a long period of time without deterioration even in the usage environment. Can be done. Therefore, it is possible to effectively prevent the contact between the cell layer 26 and the outside air, that is, the sealing of the cell layer 26, for a long period of time. However, it is not limited to the illustrated rubber-based resin.

FIGS. 11 (A) and 11 (B) show how the rubber-based seal portion 30 is brought into close contact with the current collector 22. As shown in FIG. 11A, the electrolyte layer 25 having the rubber-based sealing portion 30 formed on the separator 25a and the bipolar electrode 21 are laminated. The thickness of the rubber-based seal portion 30 is molded so as to be thicker than the thickness of the positive electrode or the negative electrode. Therefore, as shown in FIG. 11B, the battery element 20 in which the electrolyte layer 25 and the bipolar electrode 21 are laminated is pressurized from both sides along the stacking direction, and the rubber-based seal portion 30 is pressure-deformed to collect electricity. Adhere to body 22. In the present embodiment, further heat is applied when the rubber-based seal portion 30 is pressurized. The rubber-based seal portion 30 is firmly bonded (bonded or fused) to the current collector 22 by heat-sealing the rubber-based seal portion 30 in a state of being pressure-deformed. As a result, it is not necessary to keep the bipolar battery 40 in a state of being constantly pressurized from the outside, and a member or the like for constantly pressing the rubber-based seal portion 30 is not required. The portion to be pressurized may be only the portion where the rubber-based seal portion 30 is arranged, or the entire battery element 20 including the portion where the rubber-based seal portion 30 is arranged. Considering the effect of heating on the battery parts other than the rubber-based seal portion 30, the heating location is limited to the location where the rubber-based seal portion 30 is arranged, and the portion where the rubber-based seal portion 30 material is arranged. Other than that, it is desirable to perform only pressurization.

Although not shown, in the heat-sealing resin-based seal portion using a heat-sealing resin, the battery element 20 in which the electrolyte layer 25 and the bipolar electrode 21 are laminated is pressed and pressed from both sides along the stacking direction. When heated, the contact between the cell layer 26 and the outside air can be blocked by heat fusion. The heat-bondable resin is not particularly limited as long as it can exhibit an excellent sealing effect under all usage environments of the bipolar battery 40 as a sealing portion. Preferably, it is a resin selected from the group consisting of silicon, epoxy, urethane, polybutadiene, olefin resin (polypropylene, polyethylene, etc.), and paraffin wax. These heat-fusing resins are excellent in sealing properties, alkali resistance, chemical resistance, durability / weather resistance, heat resistance, etc., and for a long period of time without deteriorating their excellent performance and quality even in the usage environment. Can be maintained. Therefore, it is possible to effectively prevent the contact between the cell layer 26 and the outside air, that is, the sealing of the cell layer 26, for a long period of time. However, the resin is not limited to the heat-meltable resin exemplified. More preferably, a resin having improved adhesiveness to the current collector 22 is preferable, and examples thereof include modified polypropylene. The temperature condition for heating may be a temperature higher than the heat fusion temperature of the heat-sealing resin and within a range that does not affect other battery parts, and heat fusion is possible. It may be appropriately determined according to the type of resin. For example, for modified polypropylene and the like, about 200 ° C. is preferable, but the temperature is not limited to this. The parts to be pressurized and the parts to be heated are the same as in the case of the rubber-based seal portion 30.

The sealing portion 30 can also be composed of a three-layer film in which the non-fused layer is sandwiched between the fused layers.

As shown in FIG. 11, the size of the seal portion 30 is not limited to a size that does not protrude from the end of the current collector 22 in the surface direction, but is a size that protrudes from the end of the current collector 22 in the surface direction. May have. This is because it is possible to reliably prevent an internal short circuit due to contact between the outer peripheral edges of the current collector 22.

The seal portion can be arranged around the cell cell layer independently of the electrolyte layer, but in this case, the electrolyte layer must be laminated and the seal portion must be laminated separately at the time of battery manufacturing. However, there is a risk that the manufacturing process will be complicated or complicated. On the other hand, in the present embodiment, since the seal portion 30 is provided on the electrolyte layer 25, the electrolyte layer 25 and the seal portion 30 can be laminated at the same time at the time of manufacturing the battery. As a result of not complicating the battery manufacturing process, it is possible to reduce the cost of the product.

A pressing force acts on the positive electrode tab 50 and the negative electrode tab 60 as described later, and a state in which a plurality of bipolar batteries 40 are sandwiched is maintained. The upper and lower electrode tabs 50 and 60 and the bipolar battery 40 are preferably brought into contact with each other via an elastic body 90 having electronic conductivity (see FIGS. 1 and 12). Since the current collector 22 is formed of a metal foil, it has an uneven shape when viewed microscopically, and there is a risk that the contact resistance between the current collectors 22 and the electrode tabs 50 and 60 will increase. By bringing the upper and lower electrode tabs 50 and 60 into contact with the bipolar battery 40 via the elastic body 90 having electron conductivity, the adhesion between the two can be improved and the contact resistance between the two can be reduced. Because.

For the same reason, it is preferable that the stacked bipolar batteries 40 are brought into contact with each other via an elastic body 90 having electron conductivity. In particular, by interposing an elastic body 90 having electron conductivity between the bipolar batteries 40, it is possible to relieve the stress caused by the difference in the coefficient of thermal expansion and the temperature between the bipolar batteries 40.

The elastic body 90 having electron conductivity can be formed from an elastic material capable of reducing the contact resistance between the electrode tabs 50 and 60 and the bipolar batteries 40, and between the bipolar batteries 40, and is particularly limited. It's not a thing. For example, the elastic body 90 having electron conductivity can be formed from a conductive resin, a conductive rubber, or the like. When these materials adhere to the current collector 22 to fill the minute recesses, the adhesion to the current collector 22 is improved. The elastic body having electron conductivity may have, for example, the form of a double-sided tape. Further, by interposing the elastic body 90 having electron conductivity between the bipolar batteries 40, the current collector 22 and the current collector 22 having a minute uneven shape are compared with each other. Adhesion is improved. A conductive resin, a conductive rubber, and a metal plate may be appropriately combined and used.

When a plurality of bipolar batteries 40 are held by the upper and lower electrode tabs 50 and 60, it is preferable to use a conductive rubber sheet for the elastic body 90 having electron conductivity. By using the conductive rubber sheet, adhesion, protection of the current collector foil, vibration resistance, absorption of change in product thickness due to temperature change, etc. can be expected. The conductive rubber sheet is a conductive resin in which carbon or metal fine particles are dispersed in a resin, or a conductive plastic.

As a result of improving the adhesion between the elastic body 90 having electron conductivity and the current collector 22 having a minute uneven shape, the contact resistance can be reduced and the output of the battery module 11 can be increased. When the contact resistance between the electrode tabs 50 and 60 and the bipolar battery 40 and between the bipolar batteries 40 is small, for example, when the flatness of the current collector 22 is improved, the electron conductivity It is not always necessary to provide the elastic body 90 having the above. In the figure, for ease of understanding, the elastic body 90 having electron conductivity is shown protruding from the end of the bipolar battery 40 in the plane direction, but the present invention is not limited to this case.

FIG. 12 is a perspective view showing the internal structure of the battery module 11 according to the second embodiment, FIG. 13 is a view showing an arrangement state of sensors included in the bipolar battery 40, and FIG. 14 is a view showing a bipolar battery in an outer case 100. 40, a perspective view showing a state in which an elastic body 90 having electron conductivity, electrode tabs 50, 60, etc. are housed, FIG. 15 is a perspective view showing a state when the battery module 11 according to the second embodiment is sealed. , FIG. 16 is a cross-sectional view of an electrode extraction portion of the battery module 11 according to the second embodiment, and FIG. 17 is a plan view of the battery module 11 according to the second embodiment.

With reference to FIGS. 12 to 14, a group of bipolar batteries thus laminated via the elastic body 90 having electron conductivity and having electrode tabs 50 and 60 on both sides in the stacking direction is described, for example. It is housed in a metal outer case 100 such as aluminum. The outer case 100 is a flat hollow rectangular parallelepiped metal container composed of a box-shaped accommodating portion 100a and a flat plate-shaped lid 100b covering the opening thereof. It is engaged by a fastening means such as a screw or an engaging means such as caulking. Further, electrode insertion portions 100c and 100d for arranging the electrode extraction portions 51 and 61 of the electrode tabs 50 and 60 are formed in the central portion of the short side side wall located on both sides in the longitudinal direction of the accommodating portion 100a. The electrode insertion portions 100c and 100d are formed by rectangular notches recessed toward the bottom surface side.

In FIG. 12, the positive electrode tab 50 shown on the upper side is laminated on the positive electrode side of the uppermost bipolar battery 40 via the elastic body 90 having electron conductivity, and the negative electrode tab 60 shown on the lower side is the lowest bipolar battery. It is laminated on the negative electrode side of the battery 40 via the elastic body 90 having the electron conductivity, and the electrode tabs 50 and 60 are formed with electrode take-out portions 51 and 61 for taking out the electrodes outside the outer case 100. Has been done. The electrode take-out portion 51 of the positive electrode tab 50 is formed by extending to the right side in the plane direction, bending downward in the stacking direction, and bending to the right side in the plane direction again in FIG. 12, and the electrode insertion portion 100c of the accommodating portion 100a. It is designed to be located on top. On the other hand, the electrode take-out portion 61 of the negative electrode tab 60 is formed by extending to the left side in the plane direction, bending upward in the stacking direction, and bending to the left side in the plane direction again in FIG. 12, and the electrode insertion portion of the accommodating portion 100a. It is designed to be located on 100d.

In the present embodiment, as described above, since the outer case 100 is made of metal, an insulating film 110 is provided on the electrode insertion portions 100c and 100d of the accommodating portion 100a. Further, a sheet-shaped elastic body 120 is interposed between the bottom surface of the accommodating portion 100a and the negative electrode tab 60, and between the inner surface of the lid 100b and the positive electrode tab 50. Since the outer case 100 is made of metal, the elastic body 120 is also made of an insulating material, for example, a rubber sheet. Therefore, it is possible to prevent the positive electrode tab 50 and the negative electrode tab 60 from being short-circuited via the metal outer case 100.

By interposing a sheet-shaped elastic body 120 between the inner surface of the outer case 100 and the flat plate-shaped electrode tabs 50 and 60, the elastic body 90 having electron conductivity is laminated in the outer case 100. Simply by storing the bipolar battery group and the electrode tabs 50 and 60, the electrode tabs 50 and 60 are pressed against the current extraction surface of the bipolar battery group by the elastic force of the elastic body 120, and the power generation element of each bipolar battery 40 is pressed. To. Therefore, the batteries constituting the power generation element can be brought into surface contact with each other to be electrically connected, and it is not necessary to lead out the terminals from the outer case 100 to the outside, and it is not necessary to weld and join the terminals to each other. , The battery module 11 can be easily manufactured by simplifying a series of manufacturing operations.

Inside the outer case 100, the bipolar battery group repeatedly expands and contracts due to temperature changes due to charging and discharging. Further, as described above, the positive electrode tab 50 and the negative electrode tab 60 are in surface contact with the upper and lower electrode extraction surfaces of the bipolar battery group via the elastic body 90 having electron conductivity, and are electrically connected to each other. That is, by arranging the elastic body 120 between the inner surface of the outer case 100 and the electrode tabs 50 and 60, the bipolar batteries 40 and the electrodes while absorbing the expansion and contraction of the bipolar battery group inside the outer case 100. Conductivity with tabs 50 and 60 can be maintained. As described above, the pressing force acts on the power generation element of the bipolar battery group by interposing the sheet-shaped elastic body 120 between the inner surface of the outer case 100 and the electrode tabs 50 and 60. , An elastic body 90 having electronic conductivity interposed between the bipolar batteries 40 and between the electrode extraction surface of the bipolar battery group and the electrode tabs 50 and 60 is formed into a current collector 22 having a minute uneven shape. It can be brought into close contact, and uniform and good electrical contact can be obtained.

Further, in order to reduce the contact resistance between the electrode take-out surface of the bipolar battery group and the electrode tabs 50 and 60, it is necessary to apply a predetermined pressure from the elastic body 120 to the electrode tabs 50 and 60. That is, when the elastic body 120 has the minimum contraction of the bipolar battery group (when the bipolar battery group has the thickness at which the bipolar battery group is most contracted), the elastic body 120 is formed at the contact portion between the electrode extraction surface of the bipolar battery group and the electrode tabs 50 and 60. It is necessary to have an elastic force capable of applying a predetermined pressure. Here, the predetermined pressure is, for example, when a rubber sheet having a Young's modulus (elastic modulus) of 1 MPa and a thickness of 1 mm is used as the elastic body 120, the inner surface of the outer case 100 and the electrode tabs 50 and 60 This is the pressure obtained by setting the gap to about 990um. Further, by using the sheet-shaped (flat plate-shaped) elastic body 120, it is possible to absorb the unevenness of the flat bipolar battery 40 and apply a uniform pressure.

Further, the elastic body 120 preferably has a thickness capable of absorbing thermal expansion in the stacking direction of the bipolar battery group, and when the bipolar battery group has the maximum expansion (when the bipolar battery group has the most expanding thickness). ), It is necessary to keep the pressing force so as not to give a load to the seal portion 30 of the bipolar battery 40. When the battery module 11 is composed of the bipolar battery 40 as in the present embodiment, it is necessary to consider the liquid leakage of the electrolyte layer 25 between the bipolar electrodes 21, and when an excessive pressing force is applied, This is because a load is applied to the seal portion 30 and it causes liquid leakage. Therefore, the thickness of the elastic body 120 is defined based on the elastic modulus of the material, the minimum pressure sufficient to maintain conductivity, and the maximum pressure capable of protecting the seal 30. Since the elastic body 120 has a thickness capable of absorbing the expansion of the bipolar battery group in the stacking direction, the stress caused by the difference between the temperature change and the coefficient of thermal expansion can be alleviated, and the deterioration due to strain and metal fatigue can be reduced. it can.

The elastic body 120 preferably has a friction coefficient at which the bipolar battery group does not move in the outer case 100 when a repetitive stress such as vibration or impact is applied. As a result, when the battery module 11 is mounted on an electric vehicle or the like, even if repeated stresses such as vibration and impact are applied, it is possible to prevent the bipolar battery group from moving in the outer case 100, and the battery fails. Can be prevented. Further, it is preferable that the elastic body 120 has heat dissipation property to the outer case 100.

Further, as shown in FIG. 12, by arranging the temperature sensor wiring 170 between the positive electrode tab 50 or the negative electrode tab 60 and the elastic body 90 having electron conductivity, the temperature at the center of the battery can be measured, and the battery can be measured. Battery life can be improved by directly measuring the core temperature and controlling the load on the battery. Furthermore, by measuring the pressure at the center of the battery, it is possible to detect an abnormality such as gas generation more quickly, and by controlling the load on the battery, the battery life can be improved.

In this case, as shown in FIG. 13A, it is preferable to provide a notch (sensor accommodating portion) 95 for accommodating the temperature sensor wiring 170 in the elastic body 90 having electron conductivity. The temperature sensor wiring 170 is covered with an insulator 115 as shown in FIGS. 13 (B) to 13 (D). Therefore, the current does not flow in the thickness direction in the sensor accommodating portion 95, which causes the current distribution inside the battery to vary. In order to reduce this, as shown in FIGS. 13 (E) to 13 (G), the upper and lower parts of the battery stacking portion of the sensor 171 are covered with the conductive material 125 in the plane direction from the periphery of the sensor accommodating portion 95. It is also possible to promote the inflow of current, reduce the variation in the current distribution, and make the charge / discharge distribution of the battery uniform.

As shown in FIG. 14, the bipolar battery group in which the elastic body 90 having electron conductivity is interposed and the electrode tabs 50 and 60 are housed in the accommodating portion 100a of the outer case 100, and the electrodes of the electrode tabs 50 and 60 are housed. The take-out portions 51 and 61 are arranged on the insulating film 110 of the electrode insertion portions 100c and 100d. Then, a bus bar 130 made of a conductive metal flat plate is arranged on the electrode take-out portions 51 and 61, and the bus bar 130 is fixed via a resin plate 140 by a fastening means 150 such as a plastic screw. Further, a rectangular frame-shaped gasket 160 is arranged on the upper edge surface of the side wall of the accommodating portion 100a. In the illustrated example, since the electrode insertion portions 100c and 100d are notched, the gasket 160 is not arranged in this portion, but the gasket 150 is continuously passed over the resin plate 140 fixing the bus bar 130. May be placed. The sealing performance of the outer case 100 is ensured by inserting the gasket 160 between the upper edge surface of the side wall of the accommodating portion 100a and the inner surface of the lid body 100b. In the present embodiment, metal is used as the constituent material of the exterior case 100 because it has the largest surface area in contact with the atmosphere. Therefore, a material having low moisture permeability is used to prevent moisture from entering the case. Because. The temperature sensor wiring 170 and the control wiring 180 of each bipolar battery 40 extend out of the case so as to pass through the upper surface of the gasket 160, and the elastic body 120 is installed so as to cover the opening of the housing portion 100a. The lid 100b is arranged and fixed by a fastening member (not shown) such as a screw (see FIG. 15).

Next, the internal space of the outer case 100 is filled with epoxy resin. This is to prevent excessive pressure from being applied to the seal portion 30 due to the change in internal pressure accompanying the temperature change of the gas when the gas remains in the outer case 100. To fill the epoxy resin, first, the battery module 11 is loaded in a vacuum chamber (not shown), the inside of the chamber is evacuated, and then the epoxy injection port 210 opened in the short side wall of the accommodating portion 100b is immersed in the epoxy resin liquid. To do. Then, the inside of the chamber is returned to the atmospheric pressure, and after waiting for a while, the epoxy injection port 210 is taken out from the epoxy resin liquid to complete the filling of the epoxy resin. Then, as shown in FIG. 15, a control board 190 is fixed to one side surface of the outer case 100 in the longitudinal direction by a fastening member such as a screw, and the temperature sensor extended to the outside of the case is attached to the control board 10. Wiring 170 and control wiring 180 are connected.

In the second embodiment, since the bipolar battery 40 is provided with the seal portion 30 for blocking the contact between the cell cell layer 26 and the outside air, it is not necessary to seal the battery element 20 with an exterior material, and a plurality of battery elements 20 need to be sealed. The bipolar battery 40 is directly sandwiched by a pair of electrode tabs 50, 60. When forming the battery module 11, it is possible to simplify a series of operations for forming the battery module 11 using the bipolar battery 40 by eliminating the work of sealing the individual battery elements 20 with the exterior material. .. Further, the plurality of bipolar batteries 40 are electrically connected by simply sandwiching the plurality of bipolar batteries 40 between the upper and lower electrode tabs 50 and 60 and storing them in the outer case 100 via the insulating elastic body 120. To. When electrically connecting a plurality of bipolar batteries 40, it is not necessary to join the terminals for current extraction by welding or to connect them via a connecting member such as a bus bar. From this point of view as well, a series of operations for forming the battery module 11 can be simplified. Since the bipolar batteries 40 are directly connected to each other or via an elastic body 90 having electronic conductivity without interposing a terminal for taking out a current, the output of the battery module 11 can be increased. Since the exterior material and the terminal for taking out the current are not required, the volume of the battery module 11 can be reduced accordingly. Further, the current can be taken out only by sandwiching and holding a plurality of bipolar batteries 40 between the upper and lower electrode tabs 50 and 60, and the structure for taking out the current can be simplified. As described above, the battery module 11 has a structure utilizing the advantage of the bipolar battery 40 that the current flows in the stacking direction in the battery element 20, and the battery module 11 using the bipolar battery 40 can be easily formed. It becomes.

That is, according to the battery module 11 of the second embodiment, the retention of each bipolar battery 40 and the protection of the battery from moisture are achieved, the control terminal is insulated, the control terminal is taken out from the seal structure, and the like. Since the series of operations is simplified, it is possible to provide a low-cost assembled battery having a small volume.

Since a plurality of bipolar batteries 40 are electrically connected in series, it is possible to easily meet the demand for output simply by changing the number of the bipolar batteries 40 connected in series.

The configuration of the bipolar battery 40 is not particularly limited as long as it uses known materials used in general lithium ion secondary batteries, except for those described in particular. Hereinafter, the current collector, the positive electrode active material layer, the negative electrode active material layer, the electrolyte layer, and the like that can be used in the bipolar battery 40 will be described for reference.

(Current collector) The current collector that can be used in the present embodiment is not particularly limited, and conventionally known current collectors can be used. For example, aluminum foil, stainless steel foil, nickel-aluminum clad material, copper-aluminum clad material, or a plating material combining these metals can be preferably used. Further, it may be a current collector in which the metal surface is coated with aluminum. In some cases, a current collector in which two or more metal foils are laminated may be used. From the viewpoint of corrosion resistance, ease of production, economy, etc., it is preferable to use aluminum foil as a current collector.

The thickness of the current collector is not particularly limited, but is about 1 μm to 100 μm.

(Positive electrode active material layer) The positive electrode contains a positive electrode active material. In addition to this, a conductive auxiliary agent, a binder and the like may be included. It is sufficiently permeated into the positive electrode and the negative electrode as a gel electrolyte by chemical cross-linking or physical cross-linking.

As the positive electrode active material, a composite oxide of a transition metal and lithium, which is also used in a solution-based lithium ion battery, can be used. Specifically, LiCoO₂Li / Co composite oxides such as LiNiO₂Li / Ni-based composite oxides such as spinel LiMn₂O₄Li / Mn-based composite oxides such as LiFeO₂Li / Fe-based composite oxides and the like can be mentioned. In addition, LiFePO₄Phosphate compounds and sulfuric acid compounds of transition metals and lithium such as; V₂O₅, MnO₂, TiS₂, MoS₂, MoO₃Transition metal oxides and sulfides such as; PbO₂, AgO, NiOOH and the like.

The particle size of the positive electrode active material may be such that the positive electrode material can be made into a paste and formed by spray coating or the like according to the manufacturing method, but in order to further reduce the electrode resistance of the bipolar battery, the electrolyte is a non-solid solution type. It is preferable to use a battery having a particle size smaller than that of a commonly used lithium-ion battery. Specifically, the average particle size of the positive electrode active material is preferably 0.1 μm to 10 μm.

The polymer gel electrolyte is a solid polymer electrolyte having ion conductivity containing an electrolytic solution usually used in a lithium ion battery, but further in a polymer skeleton having no lithium ion conductivity. Also included are those in which a similar electrolyte is retained.

Here, the electrolyte solution (electrolyte salt and plasticizer) contained in the polymer gel electrolyte may be any one usually used in a lithium ion battery, for example, LiPF.₆, LiBF₄, LiClO₄, LiAsF₆, LiTaF₆, LiAlCl₄, Li₂B₁₀Cl₁₀Inorganic acid anion salts such as LiCF₃SO₃, Li (CF)₃SO₂)₂N, Li (C₂F₅SO₂)₂Contains at least one lithium salt (electrolyte salt) selected from organic acid anionic salts such as N, and cyclic carbonates such as propylene carbonate and ethylene carbonate; chains such as dimethyl carbonate, methyl ethyl carbonate and diethyl carbonate. Solvents; Ethers such as tetrahydrofuran, 2-methyl tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane, 1,2-dibutoxyethane; lactones such as γ-butyrolactone; nitriles such as acetonitrile; Esters such as methyl propionate; Amides such as dimethylformamide; Organic solvents (plasticizers) such as aprotic solvents in which at least one or two or more selected from methyl acetate and methyl formate are mixed. The used one can be used. However, it is not limited to these.

Examples of the polymer having ionic conductivity include polyethylene oxide (PEO), polypropylene oxide (PPO), and copolymers thereof.

As the non-lithium ion conductive polymer used for the polymer gel electrolyte, for example, polyvinylidene fluoride (PVDF), polyvinyl chloride (PVC), polyacrylonitrile (PAN), polymethylmethacrylate (PMMA) and the like are used. it can. However, it is not limited to these. Since PAN, PMMA, etc. fall into the category of having almost no ionic conductivity, they can be used as the above-mentioned polymers having ionic conductivity, but here, they are used as polymer gel electrolytes. This is exemplified as a polymer having no lithium ion conductivity.

Examples of the lithium salt include LiPF.₆, LiBF₄, LiClO₄, LiAsF₆, LiTaF₆, LiAlCl₄, Li₂B₁₀Cl₁₀Inorganic acid anion salts such as Li (CF)₃SO₂)₂N, Li (C₂F₅SO₂)₂An organic acid anion salt such as N or a mixture thereof can be used. However, it is not limited to these.

Examples of the conductive auxiliary agent include acetylene black, carbon black, graphite and the like. However, it is not limited to these.

In the present embodiment, these electrolytic solutions, lithium salts, and polymers (polymers) are mixed to prepare a pregel solution, which is impregnated into the positive electrode and the negative electrode.

The blending amount of the positive electrode active material, the conductive auxiliary agent, and the binder in the positive electrode should be determined in consideration of the purpose of use of the battery (emphasis on output, emphasis on energy, etc.) and ionic conductivity. For example, if the amount of the electrolyte, particularly the solid polymer electrolyte, in the positive electrode is too small, the ion conduction resistance and the ion diffusion resistance in the active material layer increase, and the battery performance deteriorates. On the other hand, if the amount of the electrolyte, particularly the solid polymer electrolyte, in the positive electrode is too large, the energy density of the battery will decrease. Therefore, considering these factors, the solid polymer electrolytic mass suitable for the purpose is determined.

The thickness of the positive electrode is not particularly limited, and as described for the blending amount, it should be determined in consideration of the purpose of use of the battery (emphasis on output, emphasis on energy, etc.) and ionic conductivity. The thickness of a general positive electrode active material layer is about 10 to 500 μm.

(Negative electrode active material layer) The negative electrode contains a negative electrode active material. In addition to this, a conductive auxiliary agent, a binder and the like may be included. Except for the type of the negative electrode active material, the contents are basically the same as those described in the section of positive electrode, and thus the description thereof will be omitted here.

As the negative electrode active material, a negative electrode active material that is also used in a solution-based lithium ion battery can be used. For example, metal oxides, lithium-metal composite oxide metals, carbon and the like are preferable. More preferably, it is a carbon, a transition metal oxide, or a lithium-transition metal composite oxide. More preferably, it is titanium oxide, lithium-titanium composite oxide, or carbon. These may be used alone or in combination of two or more.

In the present embodiment, the positive electrode active material layer uses a lithium-transition metal composite oxide as the positive electrode active material, and the negative electrode active material layer uses carbon or a lithium-transition metal composite oxide as the negative electrode active material. Is used. This is because a battery having excellent capacity and output characteristics can be configured.

(Electrolyte layer) The electrolyte layer is a layer composed of a polymer having ionic conductivity, and the material is not limited as long as it exhibits ionic conductivity.

The electrolyte of the present embodiment is a polymer gel electrolyte, and is used as a polymer gel electrolyte by chemical cross-linking or physical cross-linking after impregnating a separator with a pregel solution as a base material.

Such a polymer gel electrolyte is an all-solid polymer electrolyte having ion conductivity such as polyethylene oxide (PEO) containing an electrolytic solution usually used in a lithium ion battery, but further, polyvinylidene fluoride. A polymer gel electrolyte in which a similar electrolyte is retained in the skeleton of a polymer having no lithium ion conductivity such as vinylidene (PVDF) is also included. Since these are the same as the polymer gel electrolyte described as a kind of electrolyte contained in the positive electrode, the description here will be omitted. The ratio of the polymer constituting the polymer gel electrolyte to the electrolyte is wide, and if 100% of the polymer is an all-solid polymer electrolyte and 100% of the electrolyte is a liquid electrolyte, all the intermediates thereof correspond to the polymer gel electrolyte. The term polymer electrolyte includes both a polymer gel electrolyte and an all-solid-state polymer electrolyte.

The polymer gel electrolyte can be contained in the positive electrode and / or the negative electrode as described above in addition to the polymer electrolyte constituting the battery, but different polymer electrolytes are used depending on the polymer electrolyte, the positive electrode, and the negative electrode constituting the battery. The same polymer electrolyte may be used, or different polymer electrolytes may be used depending on the layer.

The thickness of the electrolyte constituting the battery is not particularly limited. However, in order to obtain a compact bipolar battery, it is preferable to make it as thin as possible within the range where the function as an electrolyte can be secured. The thickness of a general solid polymer electrolyte layer is about 10 to 100 μm. However, the shape of the electrolyte can be easily formed so as to cover the upper surface and the outer peripheral portion of the side surface of the electrode (positive electrode or negative electrode) by taking advantage of the characteristics of the manufacturing method, regardless of the part in terms of function and performance. It is not always necessary to make the thickness almost constant.

A solid electrolyte can also be used as the electrolyte layer. By using a solid as the electrolyte, it is possible to prevent liquid leakage, prevent liquid entanglement, which is a problem peculiar to bipolar batteries, and provide a highly reliable bipolar battery. Further, since there is no liquid leakage, the configuration of the seal portion 30 can be simplified.

Examples of the solid electrolyte include polyethylene oxide (PEO), polypropylene oxide (PPO), and known solid polymer electrolytes such as copolymers thereof. The solid polymer electrolyte layer contains a supporting salt (lithium salt) to ensure ionic conductivity. As a supporting salt, LiBF₄, LiPF₆, LiN (SO)₂CF₃)₂, LiN (SO)₂C₂F₅)₂, Or a mixture of these can be used. However, it is not limited to these. Polyalkylene oxide-based polymers such as PEO and PPO are LiBF.₄, LiPF₆, LiN (SO)₂CF₃)₂, LiN (SO)₂C₂F₅)₂Lithium salts such as, etc. can be dissolved well. Further, by forming a crosslinked structure, excellent mechanical strength is exhibited.

(Third Embodiment) With reference to FIG. 18, the battery module 13 of the third embodiment is composed of two battery groups in which two bipolar batteries 40 are stacked in the vertical direction and electrically connected in series. , The bipolar electrodes 21 are arranged in a direction orthogonal to the stacking direction. In addition, the two battery groups are arranged so that they have the same electrical polarity (the upper side in the figure is the positive electrode side and the lower side is the negative electrode side), and are electrically connected in parallel via the upper and lower electrode tabs 50 and 60. Has been done. This electrical connection form is called "2 parallel x 2 series".

In the third embodiment, since the plurality of bipolar batteries 40 are electrically connected in series and parallel, it is only necessary to change the number of series connections and the number of parallel connections to meet the requirements regarding output and capacity. You can easily respond to it.

(Fourth Embodiment) The battery modules 11 (13) described above are connected in series or in parallel to form an assembled battery module 250 (see FIG. 19), and a plurality of the assembled battery modules 250 are further connected. The assembled battery 300 can also be formed by connecting in series or in parallel. In the illustrated battery module 250, a plurality of the battery modules 11 are stacked and stored in a module case, and the battery modules 11 are connected in parallel. The bus bars 130 on the positive electrode side and the negative electrode side are connected to each other in the connection holes 220 via the conductive bars 230. FIG. 19 shows a plan view (FIG. A), a front view (FIG. B), and a side view (FIG. C) of the assembled battery 300 according to the fourth embodiment of the present invention. Are connected to each other using an electrical connecting means such as a bus bar, and the assembled battery modules 250 are stacked in a plurality of stages using a connecting jig 310. How many battery modules 11 are connected to create the assembled battery module 250, and how many stages of the assembled battery modules 250 are stacked to create the assembled battery 300 are determined by the vehicle (electric vehicle) to be mounted. It may be decided according to the battery capacity and output.

According to the fourth embodiment, a battery having a high capacity and a high output can be obtained by connecting the battery modules 11 in parallel to form an assembled battery. Moreover, each of the battery modules 11 using the bipolar battery 40 has a structure that takes advantage of the bipolar battery 40 that the current flows in the stacking direction in the battery element 20, and the formation thereof is easy. Through this, it becomes easy to form the assembled battery 300 formed by electrically connecting a plurality of battery modules 11. Further, since the battery module 11 has a long life and high reliability, the assembled battery 300 also has a long life and high reliability. Even if a part of the assembled battery module 250 breaks down, it can be repaired simply by replacing the broken part.

(Fifth Embodiment) FIG. 20 is a schematic configuration diagram showing an automobile 400 as a vehicle according to a fifth embodiment of the present invention. The battery module 11 (13) and / or the assembled battery 300 described above can be mounted on a vehicle such as an automobile or a train and used as a power source for driving an electric device such as a motor. Since the battery module 11 and the assembled battery 100 are easily formed as described above, it is easy to form a drive power source mounted on the vehicle.

To mount the assembled battery 300 on the electric vehicle 400, as shown in FIG. 20, the assembled battery 300 is mounted under the seat in the center of the vehicle body of the electric vehicle 400. This is because if it is installed under the seat, the space inside the vehicle and the trunk room can be widened. The place where the assembled battery 300 is mounted is not limited to under the seat, but may be the lower part of the rear trunk room or the engine room in front of the vehicle. The electric vehicle 400 using the assembled battery 300 as described above has high durability and can provide sufficient output even after long-term use. Furthermore, it is possible to provide electric vehicles and hybrid vehicles having excellent fuel efficiency and driving performance.

In the present invention, not only the assembled battery 300 but also the assembled battery module 250 may be mounted depending on the intended use, or the assembled battery 300 and the assembled battery module 250 may be mounted in combination. May be good. Further, as the vehicle on which the assembled battery or the assembled battery module of the present invention can be mounted, the above-mentioned electric vehicle or hybrid vehicle is preferable, but the vehicle is not limited thereto.

When vibration was applied to the battery modules of each configuration shown in the first embodiment, the effect of reducing the vibration in each configuration was evaluated by experiments.

First, the flat battery was created as follows.

<u style="single">Positive electrode material</u> The following materials were mixed at a predetermined ratio to prepare a positive electrode material.

LiMn as positive electrode active material₂O₄(85wt%) was used, acetylene black (5wt%) was used as a conductive auxiliary agent, PVDF (10wt%) was used as a binder, and NMP was added as a slurry viscosity adjusting solvent for coating. A slurry was prepared by adjusting the viscosity of. A positive electrode was prepared by using stainless steel having a thickness of 15 μm as a current collector, applying the above slurry on one side, and drying the slurry.

<u style="single">Negative electrode material</u> The following materials were mixed at a predetermined ratio to prepare a negative electrode material.

Hard carbon (90 wt%) is used as the negative electrode active material, PVDF (10 wt%) is used as the binder, and NMP is added as the slurry viscosity adjusting solvent, whereby the viscosity for coating is adjusted and the slurry is adjusted. Was produced. Then, by applying the above slurry to the opposite surface of the current collector to which the positive electrode active material has already been applied to one side and drying it, a positive electrode is applied to one side of stainless steel, which is a current collector, and a negative electrode is applied to one side. The electrodes for flat batteries have been completed. After that, the electrode for the flat battery was cut to 140 x 90 mm, and the peripheral part of the electrode 10 mm was made with a part where the electrode (both positive and negative) was not applied in advance, thereby making the electrode part of 120 x 70 and the periphery. An electrode for a flat battery having a 10 mm seal margin formed on the portion was produced.

<u style="single">Electrolyte material</u> The following materials were mixed in a predetermined ratio to prepare an electrolyte material.

PC-EC 1MLiPF as electrolyte₆Using (90wt%), PVdF-HFP (10wt%) containing 10% of HFP copolymer as the host polymer, and DMC as the viscosity adjusting solvent, apply this electrolyte to the positive and negative electrodes on both sides and dry the DMC. By letting it soak, a bipolar electrode impregnated with gel electrolyte was completed.

<u style="single">Formation of gel electrolytic layer</u> A gel polymer electrolyte layer was obtained by applying the electrolyte material to both sides of a polypropylene porous film separator 20 μm and drying the DMC.

<u style="single">Laminate</u> A gel electrolyte layer was placed on the positive electrode of the flat battery electrode, and a PE film having a width of 12 mm was placed around the gel electrolyte layer to serve as a sealing material. After stacking five layers of such electrodes for flat batteries, the seal portion was pressed (heat and pressure) from above and below to fuse and seal each layer. The press was performed at a temperature of 160 ° C. for 5 seconds under a pressure of 0.2 MPa.

We created an electrode tab with a part of a 130 mm x 80 mm 100 μm Al plate that can cover the entire projection surface of a flat battery and extends to the outside of the battery projection surface. A predetermined number of flat batteries are sandwiched between the electrode tabs, the elastic body having the predetermined electron conductivity is sandwiched, vacuum-sealed with an aluminum laminate so as to cover them, and the entire flat battery is pressed on both sides at atmospheric pressure. A battery module was completed that was pressurized by the electrode tab-flat battery and enhanced contact between the flat batteries. (Example 1) In Example 1, as shown in FIG. 21, a metal material 7 having a wavy structure was interposed between the flat battery 1 and the positive electrode tab 2 as an elastic body having electron conductivity. (Example 2) In Example 2, as shown in FIG. 22, an elastic body 4b having electron conductivity was interposed between the flat plate battery 1 and the positive electrode tab 2. A conductive polymer material was used for the elastic body 4b having electron conductivity, and a material in which a carbon material was dispersed as a conductive filler in polypropylene was used as the polymer material (see FIG. 28 (B)). (Example 3) In Example 3, as shown in FIG. 23, an elastic body 4b having electron conductivity is interposed between the flat plate battery 1 and the positive electrode tab 2, and electrons are interposed between the flat plate battery 1 and the negative electrode tab 3. An elastic body 5b having conductivity was interposed. A conductive polymer material was used for the elastic body 4b having electron conductivity, and a material in which a carbon material was dispersed as a conductive filler in polypropylene was used as the polymer material. (Example 4) In Example 4, as shown in FIG. 24, an elastic body 4b having electron conductivity was interposed between the flat plate battery 1 and the flat plate battery 1. A conductive polymer material was used for the elastic body 4b having electron conductivity, and a material in which a carbon material was dispersed as a conductive filler in polypropylene was used as the polymer material. (Example 5) In Example 5, as shown in FIG. 25, an elastic body 4b having electron conductivity is interposed between the flat plate battery 1 and the positive electrode tab 2, and electrons are interposed between the flat plate battery 1 and the negative electrode tab 3. An elastic body 5b having conductivity was interposed, and further, an elastic body 4b having electron conductivity was interposed between the flat plate battery 1 and the flat plate battery 1. A conductive polymer material was used for the elastic body 4b having electron conductivity, and a material in which a carbon material was dispersed as a conductive filler in polypropylene was used as the polymer material. (Comparative Example 1) In Comparative Example 1, as shown in FIG. 26, the positive electrode tab 2 and the negative electrode tab 3 were attached to the flat battery 1 without using any elastic material. (Comparative Example 2) In Comparative Example 2, as shown in FIG. 27, two flat batteries 1 were connected in series without using any elastic material, and a positive electrode tab 2 and a negative electrode tab 3 were attached. .. &lt;Evaluation&gt; A charge / discharge test was conducted with each of the batteries of Examples 1-5 and Comparative Examples 1 and 2. In the experiment, a constant current charge (CC) was performed to 21.0 V (Examples 4 and 5 and Comparative Example 2 was 42 V) with a current of 0.5 mA, and then a constant voltage charge (CV) was performed, and the battery was charged for a total of 10 hours.

After that, the input acceleration is 24.5m / s²The battery module is vibrated by constantly applying vibration from 10 to 100 Hz, and at the same time, a heat cycle of 1 hour at 25 ° C and 1 hour at 60 ° C is repeated for 2 weeks, and then discharged to check the capacity. did.

The capacity before vibration was set to 100%, and the discharge capacity after vibration was measured. The measurement results are shown in Table 1 below. In addition. Charging and discharging is performed by constant current (CC) charging and discharging, and full charge is 21.0V (Examples 4 and 5 and Comparative Example 2 is 42V), and discharge end is 12.5V (Examples 4 and 5 and Comparative Example 2 is 25V). did. &lt;Results&gt; Comparing Comparative Example 1 and Examples 1 and 2, the elastic body is installed between at least the flat battery and one of the electrode tabs, so that the anti-vibration effect of the elastic body is obtained. You can see that. That is, when comparing the capacity retention rate after vibration in Comparative Example 1 and the capacity retention rate after vibration in Examples 1 and 2, Examples 1 and 2 having an elastic body are after vibration. It can be seen that the capacity retention rate of is large, and the decrease in capacity is suppressed by the anti-vibration effect of the elastic body.

Furthermore, it can be seen that the decrease in capacity is suppressed by the anti-vibration effect in Example 2 using a polymer material capable of alleviating thermal expansion, as compared with the case of Example 1 in which a metal material having a wavy structure is simply used. ..

The detailed mechanism of why the decrease in capacity is suppressed in Example 2 compared to Example 1 is not clear, but the capacity retention rate is improved by the elastic body absorbing the stress between the modules with respect to the thermal cycle. it is conceivable that.

Further, in the case of Example 3, since an elastic body is inserted between the flat battery and both electrode tabs, vibration from above and below the flat plate battery can be absorbed, which is further prevented as compared with Example 1 and Example 2. The vibration effect is improved. Therefore, the capacity retention rate after vibration is larger than that in Example 1 and Example 2.

Further, when Comparative Example 2 and Example 4 are compared, it can be seen that the elastic body is installed between the flat batteries to obtain the anti-vibration effect of the elastic body.

Further, in the case of Example 5, since an elastic body is inserted between the flat batteries and between both electrode tabs, vibration from above and below the flat battery can be absorbed, and the vibration isolation effect is further improved. it is conceivable that. Therefore, in the case of the fifth embodiment, the capacity retention rate after the vibration shows the highest numerical value than any of the examples.

<tables num="1"><img file="JP2007242593A_D0001.tif" /></tables>

The present invention can be widely used in the field of manufacturing bipolar batteries.

<figref num="1">1A and 1B are schematic configuration diagrams of a conventional battery module.</figref><figref num="2">2A and 2B are schematic configuration diagrams of a battery module according to a first embodiment having a structure in which an elastic body is interposed between a flat battery and a positive electrode tab.</figref><figref num="3">3A and 3B show a first embodiment having a structure in which an elastic body is interposed between the flat battery and the positive electrode tab and between the flat battery and the negative electrode tab, respectively. It is a schematic block diagram of the battery module which concerns on.</figref><figref num="4">4 (A) and 4 (B) are schematic configuration diagrams of the battery module according to the first embodiment, which has a structure in which an elastic body is interposed between two stacked flat batteries.</figref><figref num="5">In FIGS. 5A and 5B, an elastic body is interposed between the flat battery and the positive electrode tab, between the flat battery and the negative electrode tab, and between the two stacked flat batteries. It is a schematic block diagram of the battery module which concerns on 1st Embodiment which has the structure which is provided.</figref><figref num="6">It is sectional drawing which shows the laminated structure of the battery module which concerns on 2nd Embodiment.</figref><figref num="7">It is sectional drawing which shows the bipolar battery.</figref><figref num="8">It is sectional drawing which shows the bipolar electrode.</figref><figref num="9">It is sectional drawing which provides the explanation of the cell cell layer.</figref><figref num="10">10 (A) to 10 (D) are diagrams showing the state of the manufacturing process of the electrolyte layer in which the seal portion is formed on the separator stepwise.</figref><figref num="11">FIG. 11 (A) is a cross-sectional view of a main part showing a state in which an electrolyte layer having a seal portion formed on a separator and a bipolar electrode are laminated, and FIG. 11 (B) is a battery element in which an electrolyte layer and a bipolar electrode are laminated. Is a cross-sectional view showing how the seal portion is brought into close contact with the current collector by applying pressure from both sides along the stacking direction.</figref><figref num="12">It is a perspective view which shows the internal structure of the battery module which concerns on 2nd Embodiment.</figref><figref num="13">It is a figure which shows the arrangement state of the sensor which a bipolar battery has.</figref><figref num="14">It is a perspective view which shows the state which the bipolar battery, the elastic body, the electrode tab and the like are housed in the outer case.</figref><figref num="15">It is a perspective view which shows the state at the time of sealing of the battery module which concerns on 2nd Embodiment.</figref><figref num="16">It is sectional drawing of the electrode taking-out part of the battery module which concerns on 2nd Embodiment.</figref><figref num="17">It is a top view of the battery module which concerns on 2nd Embodiment.</figref><figref num="18">It is sectional drawing which shows the laminated structure of the battery module which concerns on 3rd Embodiment.</figref><figref num="19">It is a schematic block diagram of the assembled battery which concerns on 4th Embodiment.</figref><figref num="20">It is a figure which shows the state which the assembled battery which concerns on 5th Embodiment is mounted on a vehicle.</figref><figref num="21">It is a block diagram of the battery module which concerns on Example 1. FIG.</figref><figref num="22">It is a block diagram of the battery module which concerns on Example 2. FIG.</figref><figref num="23">It is a block diagram of the battery module which concerns on Example 3. FIG.</figref><figref num="24">It is a block diagram of the battery module which concerns on Example 4. FIG.</figref><figref num="25">It is a block diagram of the battery module which concerns on Example 5.</figref><figref num="26">It is a block diagram of the battery module which concerns on Comparative Example 1.</figref><figref num="27">It is a block diagram of the battery module which concerns on Comparative Example 2.</figref><figref num="28">It is a schematic block diagram of an elastic body.</figref>

Code description

11 battery module, 20 power generation element, 21 bipolar electrode, 22 current collector, 23 positive electrode active material layer, 24 negative electrode active material layer, 25 electrolyte layer, 25a separator, 26 cell cell layer, 30 seal, 40 bipolar battery, 50 Positive electrode tab, 51, 61 Electrode take-out part, 60 Negative electrode tab, 90 Conductive elastic body, 100 Exterior case, 100a housing part, 100b lid, 100c, 100d electrode insertion part, 110 Insulation film, 120 Elastic body, 130 Bus bar, 140 resin plate, 150 fastening member, 160 gasket, 170 temperature sensor wiring, 180 control wiring, 190 control board, 210 epoxy inlet, 220 connection hole, 230 conductive bars, 250 battery modules, 300 batteries, 310 connection jigs, 400 vehicles.