High performance energy storage devices

[0001] The present invention relates to high performance lead-acid batteries.

[0002] There is an increasing demand for the development and introduction of vehicles that do not rely almost entirely on fossil fuels to combat air pollution in urban environments and reduce the combined consumption of limited resources of fossil fuels. Such vehicles fall into three main classes: electric vehicles (EV), hybrid electric vehicles (REV) and partly hybrid electric vehicles (also known as 42 volt vehicles).

[0003] Electric vehicles and hybrid electric vehicles can use many different types of batteries, including lead-acid batteries. Partially hybrid electric vehicles can mainly use lead-acid batteries due to lower costs. Hybrid and partially hybrid electric vehicles are based on a combination of an internal combustion engine and a battery for supplying energy. Due to the increased on-board energy demand of current luxury cars (cars with internal combustion engines), the capabilities of current 14-volt alternators are close to or exceed their limits. Thus, partially hybrid electric vehicles have been developed. These partially hybrid electric vehicles use a 36-volt battery and a 4.2-volt alternator. Partially hybrid electric vehicles have some advantages over existing cars with internal combustion engines, including greater use of electrically generated energy, leading to lower emissions.

[0004] Although significant progress has been made in developing new batteries and power grids for vehicles based at least in part on electricity, the batteries used in these vehicles are still a source of many problems.

[0005] All such batteries have different requirements on the battery in terms of the current consumed and supplied when the battery is being charged at various stages of the vehicle's operation. For example, a high discharge rate from the battery is necessary to enable acceleration or engine start in electric and hybrid electric vehicles, respectively. The fast battery charging speed is associated with regenerative braking.

[0006] In a situation in which lead-acid batteries are used, especially in hybrid and partially hybrid electric vehicles, the high rate of battery discharge and charging results in the formation of a lead sulfate layer on the negative surface of the plate, and the formation of hydrogen / oxygen on the plates, negative and positive. This is mainly due to the high demand for battery power. The partial charge (PSoC) states in which these batteries usually work are 20-100% for electric vehicles, 40-60% for hybrid electric vehicles, and 70-90% for partially hybrid electric vehicles. This is a partial load condition with a high load (HRPSoC). When simulated work under HRPSoC, as in the operation of a hybrid and partially hybrid electric vehicle, lead-acid batteries suffer premature failure mainly due to the gradual accumulation of lead sulfate on negative plate surfaces. This is because lead sulfate cannot be efficiently converted back to spongy lead during charging due to regenerative braking or by the engine. Ultimately, this lead sulfate layer develops to such an extent that the effective surface area of ​​the plate decreases significantly and the plate can no longer provide the higher currents required by the vehicle. This significantly reduces the potential battery life.

[0007] In other technical fields, including mobile or cellular phone techniques, it would be beneficial to develop alternative types of batteries that offer increased total usage and operation time meeting the various energy requirements of the device.

[0008] Accordingly, there is a need for modified batteries, including lead-acid batteries, which have an increased lifetime and / or improved overall performance compared to current batteries.

[0009] US-A-6 117 585 discloses a hybrid energy storage device comprising a first, second and third electrode, a first electrolyte placed between the first and second electrodes, and a second electrolyte placed between the second and third electrodes. The first and second electrodes (together with the first electrolyte between them) form a battery. The second and third electrodes (together with the second electrolyte between them) form a capacitor. The first and third electrodes are directly connected to each other, so that the battery and capacitor are connected in parallel. In a specific example of the device disclosed in US-A-6,117,585, the first (battery) electrode was formed of a NiOOH material coating a nickel substrate, the third (condenser) electrode was formed of a Ni-Co alloy coated on a nickel substrate, and the second (common) electrode was made of zinc. The first and second electrolyte contain KOH. A more general discussion of US-A-6 13 7 585 discloses examples of some common high energy materials that have been used as anodes in rechargeable aqueous batteries, including cadmium, metal hydrides, lead and zinc, while cathodes are made of nickel oxide, oxide lead, silver and oxygen or air (with catalyst). There is also a general discussion of high-energy anode materials for lithium-ion rechargeable batteries.

[0010] JP 10 021900 A discloses a lead acid battery having a positive electrode plate formed of lead oxide containing antimony oxide containing tin oxide.

[0011] US-A-5,439,756 discloses an energy storage device having the same general construction as described above for US-A-6,117,585.

[0012] JP 04 043557 A discloses a hybrid battery having the characteristics of both a double electric layer capacitor and the battery itself, which allows it to maintain a stable voltage for a long time.

Summary of the Invention [0013] According to the present invention, there is provided a lead-acid battery comprising an alternating series of positive and negative electrodes and electrolyte in contact with the electrodes, characterized in that:

at least one pair of positive and negative electrodes or electrode areas stores capacitively energy, and one of these electrodes or one of the regions contains a shell of capacitor electrode material, at least one pair of positive lead dioxide and negative lead electrode or battery electrode areas stores energy electrochemically, and the electrolyte is sulfuric acid, and the positive electrodes are directly connected by the first conductor and the negative electrodes are directly connected by the second conductor.

[0014] The lead or negative lead electrodes or electrode areas define the battery part and the pair of positive and negative electrodes or capacitively storing electrode areas define the capacitor part.

[0015] The battery part and the condenser part of the lead-acid battery are connected in parallel into one common unit. As a result, the capacitor portion preferably draws or releases a charge during high current charging or discharging. This is because the capacitor part has a lower internal resistance than the battery part, and the first will absorb and release the load during fast charging (e.g. during regenerative braking) or during quick discharge (e.g. during vehicle acceleration and engine start-up). As a result, the capacitor part will share fast operation with the battery part, which will ensure a much longer life for the lead-acid battery. All this is achieved without any electronic control or switching between the battery and capacitor parts.

[0016] According to one embodiment, the positive lead dioxide electrode is common to two parts and is sandwiched between a lead-based negative electrode and a negative capacitor electrode.

[0017] It should be understood that an inverse system can be used in which the lead-based negative electrode is a common electrode. A lead-based negative electrode will define a capacitor with a positive capacitor electrode.

[0018] Thus, considering two alternative systems, one embodiment of the lead-acid battery according to the invention is such that:

at least one removable electrode is a lead-based negative electrode;

at least one positive electrode is a positive lead dioxide electrode;

at least one positive or negative electrode is a capacitor electrode; and the electrochemical energy storage areas are formed by a lead-based negative electrode and a lead-based positive electrode; and capacitive energy storage areas are a capacitor electrode and one electrode selected from a lead-based negative electrode and a lead-dioxide positive lead electrode.

[0019] According to this embodiment, each of the capacitor electrodes can be a positive or negative electrode separately.

[0020] The lead-acid battery contains an alternating series of positive and negative electrodes. Of the alternating electrodes, each can be a battery electrode, a capacitor electrode, or a combined battery / capacitor electrode. These types of electrodes will be described in detail below.

[0021] It has been found that if there is a mismatch in the window of potentials or the range of potentials of one of the electrodes, hydrogen gas evolution may occur. This is especially the case when the cell voltage is greater than the electrode potential range. The evolution of hydrogen gas is undesirable because it leads to premature battery failure at the electrode, where gassing occurs.

[0022] To avoid mismatching, in accordance with further embodiments, at least one of the negative capacitor electrodes comprises a large surface area capacitor material, and one or more additives selected from lead, zinc, cadmium, silver and bismuth oxides, hydroxides or sulfates. The additives are preferably added in the form of oxides. The additives are preferably lead and / or zinc additives, most preferably lead and / or zinc oxide.

[0023] Mismatch can also occur at the positive capacitor electrode. Thus, in accordance with some embodiments in which the battery comprises a positive capacitor electrode, the positive capacitor electrode includes:

capacitor material with a large surface area,

pb₂ABOUT₃, antimony oxide, hydroxide or sulfate, and optionally one or more additives selected from iron and lead oxides, hydroxides and sulfates.

[0024] A negative capacitor electrode based on the above idea comprises a current collector and a paste-like coating, the paste-like coating containing capacitor materials with a large surface area, a binder and 5-40% by weight, based on the weight of the paste-like coating, additive or additive mixture selected from oxides , lead, zinc, cadmium, silver and bismuth hydroxides or sulphates, provided that the additive contains at least one lead or zinc oxide, hydroxide or sulphate.

[0025] The new positive capacitor electrode comprises a current collector and a paste-like coating, the paste-like coating containing a large surface area capacitor material, a binder and 10-40% by weight, based on the weight of the paste-like coating, of a mixture of additives including:

pb₂ABOUT₃, antimony oxide, hydroxides or sulfate, and optionally one or more iron and lead oxides, hydroxides or sulfates.

Brief description of the drawings [0026]

Figure 1 is a schematic side view of a lead-acid battery in accordance with one embodiment of the invention;

Figure 2 is a schematic top view of the lead-acid battery of figure 1;

Figure 3 is a graph representing the current profile of a single cycle test run on the battery of the embodiment of figures 1 and 2;

Figure 4 is a graph representing the duty cycles of the battery of figures 1 and 2 and the comparative battery;

Figure 5 is a schematic side view of a lead-acid battery in accordance with a second embodiment of the invention;

Figure 6 is a schematic side view of one of the negative electrodes of the lead-acid battery of figure 5;

Figure 7 is a graph representing the rate of hydrogen evolution from a negative capacitor electrode according to the fourth embodiment of the invention, compared to a standard carbon electrode and a standard lead-based negative electrode;

Figure 8 is a schematic side view representing the battery electrode system according to the third embodiment of the invention.

Detailed description of the invention [0027] The present invention is described below in further detail with reference to preferred embodiments of the invention.

[0028] For the avoidance of doubt, except where the context requires otherwise due to a special expression or the necessary implication, the word "include" or include ", or variations such as" includes "or" includes "or" comprising "or" including "applies in an inclusive sense, i.e. to indicate the presence of given features, but not to exclude the presence or addition of further features in various embodiments of the invention.

General features [0029] The term "lead-acid battery" is used in the broadest sense to encompass any unit containing one or more lead-acid battery cells.

[0030] The lead-acid batteries described contain at least one lead-based negative electrode or area, at least one lead-based positive electrode or area, and at least one negative electrode or area capacitor.

[0031] Each of these types of electrodes is described below, followed by the idea of ​​the area of ​​the electrodes.

Electrode structure [0032] The electrodes generally comprise a current collector (otherwise known as a grid or plate), with active electrode material applied thereto. The active electrode material is most often applied in the form of a paste to a current collector, and in this specification the term paste refers to all such compositions containing active material applied in any way to the current collector. The term "based" used in the context of electrodes is intended to refer to active electrode material. This term is used to avoid the suggestion that the electrode is made entirely of active material because it is not. The term is also intended to indicate that the active material of a given electrode may contain additives or materials other than the specifically mentioned active material.

Lead and lead dioxide electrodes.

[0033] Lead and lead dioxide electrodes may be of any system or type suitable for use in a lead-acid battery. Generally, such electrodes are in the form of a metal grid (usually made of lead or lead alloy) supporting the electrochemically active material (lead or lead dioxide) which is applied as a paste on the grid. The paste application operation is well known in the art. Although any suitable lead or lead dioxide known in the art may be used, it would be preferable to use the lead compositions disclosed in the co-pending application PCT / AU2003 / 001404 (claiming priority from Australian Patent Application AU 2002952234) published as WO 2004/038051. it should be noted that, prior to forming the battery, the active material may not be in active form (i.e. may not be in the form of metal, or in the form of dioxide) Thus, the terms include those other forms that convert to metallic lead or lead dioxide when the battery is formed.

Capacitor Electrodes [0034] Capacitor electrodes similarly comprise a current collector and an active material coating. It is usually applied as a paste.

[0035] The term "capacitor" is used in the context of electrodes to describe electrodes that store energy due to the capacity of the double layer of the particle / solution interface between materials with a large surface area and an electrolyte solution.

[0036] There are two main classes of capacitors. One class is a "double layer capacitor" (otherwise known as an "asymmetrical capacitor") containing two such electrodes, one as positive and the other as negative. The second class are asymmetrical capacitors, which are also referred to as hybrid capacitors, "ultracapacitors" and "supercapacitors".

[0037] Asymmetric capacitors comprise one electrode storing energy in the capacity of a double layer at the particle / solution interface, and a second electrode, i.e. a Faradejan or battery type electrode, which stores pseudo-capacitance energy. The prefixes "ultra" and "super" are sometimes used to generically describe asymmetrical capacitors, and sometimes to designate such a capacitor having great storage capacity. In this application, the prefix "ultra" is most commonly used in the first sense, but is sometimes used in the second sense, as the capacitance of the battery capacitor parts of the present invention is preferably high.

[0038] Generally, as for lead and lead oxide electrodes, the capacitor electrode comprises a metal grate (usually lead alloy) and a paste coating comprising a capacitor electrode material, usually with a binder. Carboxymethyl cellulose and neoprene are examples of suitable binders for paste compositions.

[0039] The capacitor electrode material suitably contains materials with a large surface area (or for high loads) suitable for use in capacitors. Such materials are well known in the art. Such materials for a high load capacitor include large surface area carbon, ruthenium oxide, silver oxide, cobalt oxide and conductive polymers. Preferably, the capacitor electrode material comprises a carbon material with a large surface area. Examples of carbon materials with a large surface area are activated carbon, soot, amorphous carbon, carbon nanoparticles, carbon nanotubes, carbon fibers and mixtures thereof.

[0040] Often, mixtures of materials are used to achieve the right balance between surface area (and thus capacity) and conductivity. Currently, due to costs, activated carbon is the most suitable source. Some suitable activated carbon is one with a specific surface area between 1000 and 2500 m²/ g, preferably 1000-2000 m²/ G. This material is conveniently used in combination with more conductive material such as carbon black. One of the appropriate carbon blacks has a specific surface area of ​​60-1000 m²/ G. A certain suitable mixture of these materials contains 5-20% carbon black, 4080% activated carbon, 0-10% carbon fibers, and 5-25% remaining binder. All measurements are by weight unless otherwise stated.

The content of additives in the capacitor electrodes [0041] As described above, it was found that if there is a mismatch in the potential window or the operating range of one of the electrodes potential, hydrogen and / or oxygen evolution may occur. According to one embodiment, to suppress hydrogen gassing, negative capacitor electrodes comprise an additive or additive mixture including lead, zinc, cadmium, silver and bismuth oxide, hydroxide or sulfate, or a mixture thereof. In general, it is preferred that the additive contains at least one lead or zinc oxide, hydroxide or sulfate. For convenience, the additive is conveniently one or more oxides selected from lead oxide, zinc oxide, cadmium oxide, silver oxide and bismuth oxide. Preferably, each of the negative capacitor electrodes contains an additive in addition to the large surface area capacitor material. Because of toxicity, cadmium compounds are not preferred, so the composition preferably contains a lead and / or zinc compound, and optionally a silver compound. For reasons of cost, silver oxide and bismuth oxide are usually avoided.

[0042] Regardless of the form in which the additive is added, when the conductor comes into contact with the electrolyte (for example, sulfuric acid), the additive may react with the electrolyte and thus transform into another metal compound derived from the initial metal oxide, sulfate or hydroxide . References to oxides, sulphates and hydroxides from given additives should be read as including the reaction products between the additives and the electrolyte. Similarly, if, during the state of charge or discharge of the battery, the additive transforms into another form in redox reactions, references to oxides, sulphates and hydroxides should be read as including the redox reaction products of those additives.

[0043] To suppress oxygen gassing, the positive capacitor electrodes preferably comprise:

capacitor material with a large surface area (as described above),

pb₂ABOUT₃ ("Red lead") λ antimony oxide, hydroxide or sulfate, and optionally one or more additives selected from iron and lead oxides, hydroxides and sulfates.

[0044] The antimony compound is advantageous in suppressing (oxygen) gassing at a positive capacitor electrode. However, if it migrates to the negative capacitor electrode, it has a detrimental effect on the gassing of hydrogen on that electrode. In the absence of an antimony binding agent with a positive capacitor electrode, when the antimony compound contacts the electrolyte, it can dissolve in the electrolyte and deposit on the negative electrode when current is applied. Red lead is used to bind or prevent the transfer of antimony to a negative electrode. Lead and iron compounds (i.e. oxides, sulfates or hydroxides) are also preferred in this electrode and can also be used in a mixture of additives.

[0045] In any case, the additive is used in an amount that avoids hydrogen and oxygen gassing. This is generally an amount increasing the window of the negative and positive capacitor electrodes from typical ± 0.9V or ± 1.0V to at least ± 1.2V, and preferably at least ± 1.3V. In general, the total oxide content may be 5-40% by weight, based on the total composition of the active material (including high surface activity material, binder, and any other ingredient in the dried paste composition).

[0046] Preferably, the addition of a negative capacitor electrode contains 1-40% by weight of Pb (more preferably 1-20%), 1-20% by weight of Zn (more preferably 1-10%), 0-5% by weight of Cd and 0- 5% by weight of the compound Ag. Preferably, the whole is in the range of 5-40% by weight mentioned above. The use of ZnO alone gives good results, as does PbO alone or a mixture of PbO and ZnO.

[0047] Preferably, the addition of a positive capacitor electrode contains 0-30% by weight Pb (preferably 1-30% by weight) in the form of an oxide (any oxide), sulfate or hydroxide, 1-10% by weight Pb2O3, 0-2% by weight Fe ( preferably 1-2% by weight) in the form of an oxide, sulfate or hydroxide and 0.05 to 1% by weight Sb in the form of an oxide, sulfate or hydroxide. Preferably, Sb is added as the oxide. Preferably the total amount is in the range of 5-40% by weight mentioned above.

Other electrodes [0048] As described in further detail below, the battery may include electrodes of other types in addition to or instead of the electrodes described above. In particular, the battery may include one or more mixed capacitor-battery electrodes, such as a positive battery capacitor electrode.

[0049] In a situation where the positive capacitor electrode (as described above) contains lead oxide, it is converted to lead dioxide when the battery is being charged. Thus, a capacitor electrode containing a lead source that is converted to lead dioxide during battery operation can be considered a capacitor-battery electrode having some features of a capacitor electrode and a battery electrode.

[0050] The incorporation of a material with a large surface area such as carbon into some positive electrodes can be carried out to meet the need to balance the positive to negative electrode surface area ratio. In the absence of positive capacitor electrodes, negative capacitor electrodes with a large surface area increase the greater overall surface area of ​​the negative electrodes compared to the positive electrodes. When there is an imbalance in the surface area, electrodes with a lower surface area fail. By increasing the surface area of ​​positive electrodes, by introducing carbon with a large surface area into certain positive electrodes, the balance is improved.

[0051] As a consequence of the above, those skilled in the art understand that the battery may comprise an alternating series of positive and negative electrodes, with the electrolyte in contact with the electrodes, and a first conductor for direct connection of positive electrodes and a second conductor for direct connection of negative electrodes, where at least one pair of adjacent positive and negative electrode areas forms a capacitor (by storing capacitive energy), and at least one pair of adjacent areas of the positive and negative electrodes form a battery (by storing energy as electrochemical potential between two pairs of electrodes).

Greys [0052] The electrodes of the present invention may be composite electrodes (i.e., they may be composites of battery electrode materials and capacitor electrode materials). References to "lead-based", "lead-dioxide" and "capacitor" electrodes include areas of the electrode that have the indicated function, regardless of whether the single electrode has other areas of another type.

[0053] According to one embodiment of the invention, electrodes having regions of different types are intentionally used. According to this embodiment, the one or more negative electrodes have at least two areas, including a battery electrode material area and a capacitor electrode material area. As one example, an electrode having two regions comprises an electrode current collector, which may be of the type described above, having one side coated with paste material from a battery electrode (such as lead) and the opposite side coated with paste material from a negative capacitor electrode. Alternatively, the battery-type electrode containing the battery electrode material on both sides may be coated on one side or on any other area with the capacitor electrode material.

Physical configuration [0054] The electrodes may have any suitable shape, and thus may be in the form of a flat plate or in the form of a spirally wound plate to form prismatic or spirally wound cells. Flat plates are preferred for simplifying the design.

Rails or conductors [0055] The lead-acid battery rail can be of any suitable construction, and can be made of any suitable conductive material known in the art. The term "connected to" when used in the context of busbars refers to electrical connection, although direct physical contact is preferred. If the battery does not have the configuration of a typical lead-acid battery with busbars, any conductor that does not include external circuits for the battery can be used.

Other features of the battery [0056] Generally, the battery components are included in the battery housing.

[0057] The lead-acid battery may have an electrolyte-flooded construction or with valves. When the lead-acid battery is a lead-acid battery with valves, the battery may be of any suitable construction, and may for example contain a gel electrolyte. The specific features of the battery unit corresponding to such constructions are well known in the art.

[0058] The pressure that can be used in the lead-acid battery may be in the range of 5-20 kPa for electrolyte-flooded structures and 20-80 kPa for the structure of lead-acid battery with valves.

Spacers [0059] Generally, each of the positive and negative electrodes is separated from adjacent electrodes by porous spacers.

[0060] The spacers maintain a suitable separation distance between adjacent electrodes. Spacers sandwiched between directly adjacent lead-based negative electrodes and lead-based positive electrodes can be made from any suitable porous material commonly used in this field, such as porous polymeric material or absorbent glass microfiber ("AGM"). The separating distance (corresponding to the thickness of the spacer) is usually from 1-2.5 millimeters for these spacers. Suitable polymer materials useful for forming spacers between the positive and negative electrodes forming the battery part are polyethylene and AGM. The polyethylene spacers are conveniently between 1 and 1.5 millimeters thick, while the AGM spacers are between 1.2 and 2.5 millimeters respectively.

[0061] For spacers sandwiched between the positive electrode and the negative electrode of the capacitor, they are conveniently much thinner than the spacers of the battery portion of the lead-acid battery. Preferably, the spacers have a thickness between 0.01 and 0.1 millimeter, and most preferably between 0.03 and 0.07 millimeter. These spacers are conveniently made of a microporous polymeric material, such as microporous polypropylene. Other spacers are AGM and the thickness of this type of spacers is from 0.1 to 1 millimeter, preferably from 0.1 to 0.5 millimeter.

Forming lead-acid batteries [0062] After assembling the appropriate components in the battery housing, the lead-acid battery generally needs to be formed. The forming operation is well known in the art. It should be understood that references to "lead-based" and "lead-dioxide-based" materials are used to refer to lead or lead dioxide alone, metal / metal dioxide containing materials, or materials converting to lead or lead dioxide, as the case may be, on a given electrode.

[0063] As the language used above indicates, the lead-acid battery contains at least one of each type of electrode. The number of individual cells (formed by the negative and positive plates) in a battery depends on the desired voltage of each battery. For a 36-volt battery suitable for use as a partially hybrid electric vehicle battery (which can be charged up to 42 volts), this includes the use of 18 cells.

Electrode system [0064] For best performance according to one embodiment, the positive and negative electrodes are interlaced such that each positive electrode has one lead-based negative electrode on one side of its own, and one negative electrode on the opposite side. Accordingly, the system in one embodiment has alternating positive and negative electrodes, with negative electrodes being alternatively a lead-based electrode and a negative capacitor electrode. All negative electrodes (lead and carbon) are connected to the negative rail, and the positive electrodes are connected to the positive rail, so that each battery cell and ultracapacitor cell are connected in parallel in a regular lead-acid battery.

Operation [0065] As explained above, the ultracapacitor cell in the lead-acid battery system described has a lower internal resistance than the lead-acid battery cell, and thus will first absorb the released charge during fast charging (for regenerative braking) or during quick discharge (vehicle acceleration and start-up) engine). As a result, the cell of the asymmetrical capacitor will share the rapid operation of the lead-acid battery cell and will provide the lead-acid battery for a much longer operating time. More specifically, the formation of lead sulfate on the electrodes of the battery cell, which usually occurs during high-current battery charging and discharging, is minimized because high-current charging and discharging generally dissolves in the asymmetrical capacitor.

[0066] Each battery cell of one embodiment of the invention provides a voltage of 2 volts. The lead-acid battery according to one embodiment suitable for use in a wide range of applications for electric vehicle batteries contains 8 negative electrodes and 9 positive electrodes, with 4 negative electrodes being lead-based negative electrodes and the remaining 4 are capacitor electrodes, in alternating system. Changes in this system and the relative numbers of electrodes are also appropriate as long as there is a minimum of one each electrode.

EXAMPLES

Example 1 [0067] A lead-acid battery according to one embodiment of the invention suitable for testing purposes was made in the system schematically illustrated in figures 1 and

2.

[0068] Two spongy lead (negative plate) electrodes (1), two positive lead dioxide electrodes (2) and one negative carbon electrode plate (3) with a high surface area are arranged in an alternating arrangement as illustrated in figure 1 in the case of the battery (4). The positive lead dioxide electrodes (2) and the negative lead electrodes (1) were 40 millimeters wide by 68 millimeters high by 3.3 millimeters thick. The carbon electrode (3) was 40 millimeters wide by 68 millimeters high by 1.4 millimeters thick. The battery electrodes had a standard configuration and composition for lead-acid batteries, and were formed by the methods described in the detailed description above. The lead electrode forming techniques used in this example are further described in our pending application PCT / AU2003 / 001404. In short, the composition of the paste for the negative lead electrode contained lead oxide (1 kg), fiber 0.6 g, BaSO₄ 4.93 g, soot 0.26 g, H₂SO₄(relative density 1,400) 57 cm³, water 110 cm³, acid to oxide ratio 4% and paste density 4.7 g / cm³. The composition of the paste for a positive lead dioxide electrode contained lead oxide 1 kg, fiber 0.3 g, H₂SO₄ (relative density 1,400) 57 cm³, water 130 cm³, acid to oxide ratio 4% and paste density 4.5 g / cm³. Lead oxide was converted into lead and lead dioxide by the molding techniques described in our pending application.

[0069] The electrode (3) of the condenser was made of 20% by weight of carbon black with a specific surface area of ​​60 m² g (Denki Kagaku, Japan), 7.5% by weight carboxymethylcellulose, 7.5% by weight neoprene, and 65% by weight activated carbon with a specific surface area of ​​2000 m² g^_1 (Kurarekemikaru Co. Ltd. Japan).

[0070] The spacers (5, 6) were placed between adjacent electrodes. Spacers (5) of 2 mm thick absorbent glass (AGM) microfibers were placed between lead dioxide (2) and lead (1) electrodes, and microporous polypropylene spacers (6) 0.05 mm thick were inserted between the positive electrodes (2 ) and carbon electrode (3).

[0071] The battery housing (4) was filled with sulfuric acid solution (7). The positive electrodes were connected to the positive rail (8), and the negative electrodes were connected to the negative rail (9). As indicated below, for comparison purposes, for the simulation of a battery that does not contain an ultracapacitor cell, the negative capacitor plate could be disconnected from the negative bus.

[0072] For testing purposes, a charging and discharging profile has been developed to simulate typical charging and discharging requirements on a 42-volt battery for a partially hybrid electric vehicle, typically used in applications for a partially hybrid electric vehicle. The profile has a short duration (2.35 minutes) and is composed of several current stages simulating the demand for battery power during vehicle operation. They are, in order:

(a) an idle stop section involving a 2 A discharge over 60 seconds;

(b) 17.5 A high current discharge, lasting 0.5 seconds, simulating starting;

(c) discharge of the assistance power of 8.5 A for 0.5 seconds;

(d) a maximum of 14 volts / 2 A, a 70 second section of engine charging simulating battery charging during standard driving conditions;

(e) a 5-second rest period; and (f) a maximum 14-volt / 2A period correlating with regenerative charging (regenerative braking) lasting 5 seconds.

[0073] The critical stage is the start-up period during which the cell must provide 17.5 A for 0.5 seconds.

Testing [0074] To test the battery life of the example, two identical batteries were prepared, and one was then modified to disconnect the negative capacitor carbon electrode from the negative rail to match the equivalent battery without the integral capacitor feature, and hereinafter referred to as "comparative battery".

[0075] Each battery was subjected to the repeated cycles of the profile illustrated in figure 3 and described above. A 1.6 volt cut-off voltage was set, which is the usual cut-off voltage value for batteries in the field of the invention, and the batteries were subjected to repeated cycles for a charging cycle until the lowest voltage reached the cut-off value during discharge.

[0076] The test results are illustrated in figure 4. In this figure, line 10 shows the internal battery resistance profile, line 11 shows the internal battery resistance profile of example 1, line 12 shows the minimum discharge voltage profile of the comparative battery and line 13 shows the minimum voltage profile battery discharge from example 1.

[0077] During the cycles, the following observations were made:

(i) the maximum charging voltages for the reference battery and the battery of Example 1 are maintained at 2.35 volts, as shown on line 14.

(ii) the internal resistance of both batteries increases in cycles. However, the internal resistance of the comparative battery increases faster than the battery of Example 1, for example, from 19 to 25 mQ for the comparative battery and from 18 to 25 mO for the battery of Example 1.

(iii) The minimum discharge voltages of the comparative battery and battery of Example 1 decrease in cycles, but the decrease rate is higher for the comparative battery.

[0078] The comparative battery performs about 2150 cycles, while the battery of Example 1 performs 8940 cycles before the minimum discharge voltages of each battery reach a cut-off value of 1.6 volts (represented by line 15). Thus, the cyclic battery performance of Example 1 is at least four times better than the comparative battery.

Example 2 [0079] A variation of the battery of Example 1 is illustrated in Figures 5 and 6. For ease of comparison, the same numbers are used to refer to common components of two batteries.

[0080] The embodiment of this example includes three positive lead dioxide electrode plates (2) and two composite negative electrodes (16). The composite negative electrodes comprise a current collector or grille (17) with a lead-containing paste composition described above applied to one area (side) (18) and a paste containing a large surface area carbon electrode material used on the opposite side (19). The electrode formation is carried out in a manner known in the art. In a variation of this simpler embodiment, the lead-based negative electrode is made from lead applied as a paste by conventional techniques of dipping a portion of the main body into the lead paste material, then forming, and then matter! The capacitor is applied as a paste to an area or areas of this lead-based negative electrode, for example to one side of it. The positive (2) and negative composite electrodes (16) are arranged in an alternating arrangement, as illustrated in figure 5 in the case of the battery (4).

[0081] The positive lead dioxide electrodes (2) and the negative composite electrodes (16) of the embodiment illustrated in figure 5 are 40 millimeters wide by 68 millimeters high by 3.3 millimeters thick. The carbon electrode area (19) of the negative electrode takes 1.4 millimeters of thickness of the negative electrode.

[0082] The spacers (5, 6) are arranged between adjacent electrodes. The 2 mm thick microfibers (AGM) spacers (5) are placed between the lead electrodes (2) and the lead side (18) of the negative electrode, and the microporous polypropylene spacers (6) 0.05 millimeters thick are inserted between the positive the electrode (2) and the carbon side of the negative electrode (19).

[0083] The battery housing (4) is filled with sulfuric acid solution (7). The positive electrodes are connected to the positive rail (8) and the negative electrodes are connected to the negative rail (9).

Example 3 [0084] Further testing of the battery of example 1 showed that an improvement in the electrolyte drying state could be achieved by adjusting the rate of hydrogen evolution from the carbon electrode (3) during battery charging so that it was similar to that of the negative lead (1) from lead. This was achieved by replacing the carbon electrode of Example 1 with a modified carbon electrode (103) with 2.5% by weight PbO and 2.5% by weight ZnO, 65% by weight activated carbon, 20% by weight carbon black and binder (10% by weight) in the paste composition .

[0085] The rates of hydrogen evolution for this electrode were tested and compared with the electrode used in Example 1, as well as the rates of hydrogen evolution from the negative lead electrode of Example 1. The results are shown in Figure 7, where curve 20 represents the rate of hydrogen evolution from the carbon electrode, curve 21 represents the rate of hydrogen evolution from a negative lead-acid plate, and curve 22 represents the rate of hydrogen evolution from a carbon electrode with additives. Higher levels of current density recorded for a carbon electrode without the addition of oxide increases significantly at potentials falling below -1.2 V, and even more so at -1.3 V. By closer matching of the rate of hydrogen evolution from two electrodes, the battery can be operated at higher potentials without prior damage due to electrolyte drying.

[0086] The addition of CdO oxide will have a similar effect as ZnO and PbO, but due to toxicity it was not used in the tests. AgO has a similar effect, but is a costly addition and not as effective alone. In other tests, ZnO and PbO levels ranged from 1-10% and 1-20%, respectively, and AgO between 1-5%. Other oxides mentioned in the detailed description above have a similar effect as AgO.

Example 4 [0087] A further variation of the battery of Example 1 is illustrated in Figure 8. For ease of comparison, the same numbers are used to refer to common components of two batteries. Also, for simplicity, only the battery electrodes are illustrated. It should be understood that the battery further includes spacers, housing, electrolyte, rails, terminals and other battery components common in the art.

[0088] The battery of this example contains an alternating series of positive and negative electrodes. The electrodes are, from left to right, the positive electrode (2) of the lead dioxide battery, the negative electrode (3) of the lead-based battery, the second positive electrode (2) of the lead-dioxide battery, the carbon with the addition of a negative capacitor electrode of the type described in example 3 (103), the positive capacitor electrode of the accumulator as described below (23), the second carbon with the addition of a negative capacitor electrode of the type described in Example 3 (103), the second lead-based negative electrode (3) battery and the third positive electrode (2) of the lead dioxide battery. Each positive and negative electrode, respectively, are connected to a positive conductor and a negative conductor, and to the positive and negative terminals of the battery.

[0089] The battery-capacitor electrode (23) comprises a metal current collector with a mixture of activated carbon (60% by weight), carbon black (20% by weight) and 10% by weight of lead oxide applied as a paste. The paste composition is formed from 10% by weight [5% by weight carboxymethyl cellulose and 5% by weight neoprene] binder and sintered on a current collector. The electrode has a thickness of about 0.8 mm. Gassing tests show that the inclusion of SbO and red lead in this positive capacitor electrode has a beneficial effect on gassing, and therefore these additives can also be included in the positive capacitor electrode.

[0090] The battery of this example may include further alternating positive and negative electrodes of any type. In general, it is desirable to ensure that there is a certain level of matching of surface areas and hydrogenation gassing intensity of the sum of positive and negative electrodes, and enable the required number of positive and negative electrodes to produce a battery with the desired voltage.

Commonwealth Scientific and Industrial Research Organization

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