Electrochemical accumulator and vehicle comprising an electrochemical accumulator

ES 2 425 272 T3

DESCRIPTION

Electrochemical accumulator and vehicle with an electrochemical accumulator

The invention relates to an electrochemical accumulator with the features of claim 1. The invention further relates to a vehicle with an electrochemical accumulator.

High-power accumulators with high energy densities in galvanic cells are used in particular in hybrid vehicles (eg a vehicle with an accumulator and a fuel cell) and in electric vehicles (eg electric road vehicles).

High energy densities lead to the generation of a lot of heat. In order to maintain the capacity of the accumulators and to be able to guarantee it over a wide service interval (defined for example by the outside temperatures), an effective cooling of the accumulators is necessary.

Effective and economical cooling of the accumulators is achieved by air cooling. For air cooling, cooling air channels are provided in the accumulator between the individual cells, through which cooling air is guided with the aid of a fan.

It is known to collect the cooling air made available for cooling the accumulator in the air-conditioned passenger compartment. In particular, in countries with high average temperatures throughout the year, the use of outside air is not effective. Furthermore, when using the outside air, filtration systems are needed to free the cooling air of impurities (eg sand), before leading the cooling air through the accumulator. This increases the costs of these cooling systems.

High-power accumulators with high energy densities require, in addition to effective cooling, a safety system to protect the accumulator from an overpressure of gas in the batteries. The overpressure of gas in the cells can lead to sudden reactions inside the cells and ignition of the cells. This can cause damage to people and the environment.

As a safety system against gas overpressure in the cells, for example, burst openings (controlled breaking points) are integrated into the cell walls. These controlled breaking points can prevent an explosion of the batteries in the event of damage (eg short circuit, overcharging, improper treatment) related to an overpressure of gas in the batteries. The cells open under defined conditions (a given gas pressure in the cells) and at the same time reduce the overpressure of gas that has built up inside the cells. The gas exiting through the open controlled break points exits the accumulator through the cooling air channels. The gases that come out of batteries are harmful to health.

The aim of the present invention is to provide an effectively cooled, powerful and safe electrochemical accumulator, which can be used in particular for use in hybrid vehicles and electric vehicles. Another objective of the present invention is to provide a vehicle with this powerful and safe electrochemical accumulator for the user.

The object is achieved by an electrochemical accumulator (hereinafter briefly referred to as an accumulator) with the features of claim 1, as well as by a vehicle with the features of claim 9.

The accumulator according to the invention avoids the danger that the gas coming out of the batteries enters through the space for the cooling air into the passenger compartment, endangering the people who are there, the cooling air space and the aeration spaces separated in a gas-tight manner and the cooling air space and the aeration space having independent outlets outside the housing.

Thanks to this construction, it is excluded that the gas passes from the batteries to the refrigeration circuit and from there to the passenger compartment.

Due to the strict space separation of the cooling system and the aeration system, costly valve mechanisms or flaps that are necessary in known air-cooled accumulators, which separate the cooling system from the passenger compartment, are avoided. The elimination of the valve and flap mechanisms also increases the efficiency of the air cooling, since the resistances for the cooling air attached to the valve and flap mechanisms are eliminated. In addition, the accumulator according to

The invention avoids a separate cooling system from the aeration system with its own heat exchangers, which regulate the temperature of the cooling air to the required inlet temperature. Due to the high manufacturing costs of such a separate cooling system, the accumulator according to the invention represents an economical alternative.

The batteries in the accumulator according to the invention are preferably made of cylindrical shape. It is advisable to use thin-film electrodes for the cylindrical construction of the batteries, which are first inserted in a stacked manner and then wound up in the cylindrical stack. This construction allows large active electrode surfaces to be accommodated in a small space, thereby increasing the capacity of the accumulator.

In the accumulator according to the invention, the cooling air space comprises channels, which are arranged outside the stacks on the side surfaces of the cylindrical stacks. This embodiment allows direct contact between the cooling system and the batteries, thereby achieving effective cooling. Furthermore, a plurality of channels conducting cooling air may be arranged around each individual stack.

In one embodiment, the aeration space comprises cylindrical spaces, which are arranged outside the stacks on the base surfaces or on the covering surfaces of the stacks. Thanks to this construction it is possible to provide burst openings in the base surfaces or the covering surfaces of the batteries. Furthermore, this arrangement of the aeration space allows a simple separation of the cooling air space and the aeration space in the case of stacks made of cylindrical shape.

According to the invention, provision is made for the stacks to have burst openings, by means of which the interior spaces of the stacks are connected in such a way with the aeration space that gas can escape from the interior spaces of the stacks into the aeration space. The burst openings serve as an overpressure valve and evacuate the gas from the interior spaces of the stacks selectively to the aeration space.

In a special embodiment, the bursting openings are closed with bursting membranes, which, in the event of a defined overpressure in the interior spaces of the cells, allow gas to escape from the interior spaces of the cells. The bursting membranes can be designed in such a way that they rupture at a certain overpressure. However, it is also conceivable that they act as an overpressure valve, which automatically closes again when the pressure in the interior of the stack has dropped below a predefined value.

In a special embodiment, a holder is provided in the housing, to which the batteries are fixed in the assembled state.

A very powerful accumulator is obtained if the batteries are made as lithium ion batteries.

According to the invention, a vehicle is provided which is equipped with an accumulator according to the invention.

It is recommended that the cooling air in the passenger compartment be directed by means of a fan to the accumulator. The fan can be arranged between the accumulator and the passenger compartment in such a way that cooling air from the passenger compartment is forced through the accumulator. However, it is also conceivable for the fan to be arranged behind the accumulator in such a way that the cooling air from the passenger compartment is drawn through the accumulator. "Behind" here means that the accumulator is arranged between the fan and the passenger compartment. The fan generates a suction that passes both through the accumulator and through the passenger compartment, so that the cooling air is sucked in.

The vehicle according to the invention is particularly advantageous if it is designed as a hybrid vehicle or as an electric vehicle, since powerful accumulators are required in vehicles of this type. The vehicle according to the invention can be a land, water or air vehicle.

The invention will be explained in more detail with the aid of an embodiment shown in the figures set out below.

They show:

Figures 1 and 2, two perspective views of a module with a plurality of galvanic cells;

FIGS. 3, 4 and 5, three perspective views of a galvanic cell of the module of FIGS. 1 and 2.

In FIG. 1 a module of a plurality of galvanic cells 2 (hereinafter abbreviated cells) is represented.

The stacks 2 are round stacks wound cylindrically. The coiled arrangement comprises a positive electrode (not shown) and a negative electrode (not shown) with a spacer arranged between them, as well as a non-aqueous electrolyte. In the present case, the batteries 2 are lithium ion batteries.

The batteries 2 are fixed in a holder 3. The holder 3 is made of plastic.

The support 3 has a single bottom 4 and a double bottom 5. The single bottom 4 and the double bottom 5 are connected by webs 6 in such a way that they are arranged at a distance and one parallel to the other. Between respectively 2 webs 6 a channel 7 is formed. The channels 7 form a cooling air space of the accumulator according to the invention. Cooling air for cooling the stacks 2 can be conveyed through the channels 7, for example with the aid of a fan.

The double bottom 5 comprises two plates 8 arranged one parallel to the other and at a distance from each other.

Cylindrical side surfaces 9 are arranged between the plates 8, which form cylindrical spaces. For each stack 2 a side surface 9 is provided.

On the double bottom 5 side air inlets 10 are provided for the supply of cooling air.

The air inlets 10 at the edge of the module 1 are wider than the air inlets 10 which are not arranged at the edge of the module.

In figure 2 outlet slots 11 can be seen in the simple bottom 4. Through the outlet slots 11 the cooling air can come out again, entering through the air inlets 10 and passing through the channels 7. A channel 7 in an outlet groove 11. In the present case, around each stack 6 channels 7 with respectively six outlet grooves 11 are arranged. The outlet grooves 11 are arranged cylindrically around the stacks 2 and respectively have the same length. Of course, the outlet slots 11 and the channels 7 can also have different lengths.

By means of the webs 6, on the one hand, the different channels are separated from each other and, on the other hand, they serve to fix the different stacks 2.

In FIG. 3 a single stack 2 is shown in an enlarged view.

The battery 2 has a positive pole 12 and a negative pole 13. The negative pole 13 is electrically connected to the lateral surface 14 of the battery 2. The positive pole 12 is electrically isolated from the lateral surface 14 by an insulating ring 15. The Positive pole 12 is electrically connected with positive electrode in cell 2.

For clarity, only about half of the portion of the support 3 that extends around the stack 2 depicted in Figure 3 is shown; The part of the support which in figure 3 is the front part is not represented.

The stack 2 is fixed on the support 3 between the single bottom 4 and the upper plate 8 of the double bottom 5 in such a way that it cannot move in the vertical direction V with respect to the support 3.

In the horizontal direction H, the stack 2 is fixed by the webs 6.

The arrows 16 indicate the cooling air entering the air inlet 10. The cooling air flows along the channels 7 in a helical manner towards the outlet slots 11. In the outlet slots 11, the air cooling outlet comes out of support 3; this is indicated by arrows 17.

In figure 3 approximately half of the cylindrical side surface 9 can be seen.

In figure 4 it can be seen that by the cylindrical lateral surface 9, the bottom of the stack 2, 18 and the bottom plate 8 are

ES 2 425 272 T3 gas-tight separated from the inlet. The bottom 18 is designed as a burst membrane. The bursting membrane acts, on the one hand, as a gas outlet valve, when the internal gas pressure in the cell 2 rises above a predefined value. Furthermore, the bursting membrane interrupts the electrical connection between the negative electrode provided in the cell 2 and the lateral surface 14 or the negative pole 13.

Between the cell 2 and the cylinder 9 an annular seal 19 is provided, which prevents the gas 20 coming out of the cell 2 from reaching the area of ​​the inlet 10 and, therefore, of the channel 7.

In Figure 5, the stack 2 of Figures 3 and 4 is shown in an exploded representation, to illustrate the arrangement of the joint 19. The bottom 18 of the stack 2, which is made as a bursting membrane, extends a section reduced to below the edge of the lateral surface 14. In this way, the contact area of ​​the gasket 19 with the stack 2 increases, thereby increasing the effectiveness of the gasket. The diameter of the seal 19 is adapted to the bottom 18 in such a way that the seal 19 sits precisely against the bottom 18.

The contact of the gasket 19 with the cylindrical side surface 9 is increased because the upper edge of the cylindrical side surface 19 has a recess 21, against which the gasket 19 sits with tight fit (FIG. 4).