DE102011110876A1 - Energy storage device - Google Patents

Abstract

The present invention relates to an energy storage device having at least one energy storage cell with an electrode stack (2) or electrode winding and a container (1) for receiving the energy storage cell. The invention further relates to a corresponding battery arrangement and a use thereof. In order to keep impairments in the function of the energy storage cell as low as possible, at least one thermally conductive layer (10) is provided between the energy storage cell, in particular the electrode stack (2) or electrode winding, and at least one wall of the container (1), through which heat from the Energy storage cell, in particular in the direction of the wall of the container (1) can be derived.

Description

The present invention relates to an energy storage device according to the preamble of claim 1.

Energy storage devices known from the prior art have at least one electrochemical energy storage cell, which is also referred to as an electrochemical cell or galvanic cell, in the form of an electrode stack or electrode coil, which is surrounded by a housing. The electrode stack usually comprises a plurality of electrode groups each composed of two electrodes and an intermediate electrolyte layer, which are arranged side by side or one above the other. In an electrode winding at least one electrode group is wound into a so-called. Winding. The electrodes of the electrode groups of the same polarity are each electrically connected to a current conductor, via which the electrical voltage generated in the cell can be tapped from the outside.

During the charging and / or discharging process of the energy storage cell, the temperature in the cell may increase due to the electrochemical processes in the cell and the associated evolution of heat, whereby the function of the cell may be permanently impaired.

It is an object of the present invention to provide an energy storage device in which impairments of the function of the cell are kept as low as possible.

This object is achieved by an energy storage device according to claim 1.

According to the invention, a thermally conductive layer is provided between the energy storage cell, in particular the electrode stack or electrode coil, and at least one wall of the container, by which heat from the energy storage cell, in particular in the direction of the wall of the container can be derived.

The invention is based on the idea of enabling or promoting a derivation of the heat arising in the energy storage cell through a separate heat-conducting layer arranged between the energy storage cell and the container wall. In the case of a container in the form of a flat rectangular hollow body, the heat-conducting layer is arranged in particular between the side walls and the cell in order to achieve a particularly good heat dissipation. The heat dissipation can alternatively or additionally but also be supported by the fact that the heat-conducting layer between the end face and / or the bottom side of the cell on the one hand and the front or bottom wall of the container on the other hand is arranged. Due to the additional heat-conducting layer between the cell and the container, a better overall heat transfer between the cell and the wall is achieved than without such a layer. As a result, the heat generated during charging and / or discharging in the cell can always be efficiently dissipated to the outside and a high long-term stability of the cell can be ensured.

In addition, it has been shown that the additional heat-conducting layer between the cell and container helps to maintain the functionality of the energy storage device even if it is damaged from the outside or foreign bodies penetrate. The additional heat-conducting layer prevents in many cases that a foreign body, such as a projectile, can penetrate even further after penetrating the container wall. The foreign body is in this case intercepted by the heat-conducting layer, so that damage to the underlying electrode groups, in particular a short circuit, can be prevented or at least limited to deformation. But even in many cases in which the penetrating foreign body also penetrates the thermally conductive layer, short circuits between the individual electrodes can be prevented, since then the thermally conductive layer, which is preferably coated electrically insulating, with the possibly damaged electrodes while in contact can come, however, due to the electrically insulating property of the layer no short circuit occurs.

Overall, it should be noted that in the energy storage device according to the invention impairment of the function of the cell can be reduced.

In the context of the invention, an energy storage device is understood as meaning a device which is capable of picking up, storing and releasing in particular electrical energy, in particular by utilizing electrochemical processes. As an energy storage cell is understood within the meaning of the invention, a self-contained functional unit of the energy storage device, which in itself is also able to absorb electrical energy, store and release again, in particular by utilizing electrochemical processes. An energy storage device according to the invention may comprise an energy storage cell or a plurality of energy storage cells.

An energy storage cell may be, for example, but not limited to, a galvanic primary or secondary cell (within the scope of this application Primary or secondary cells indiscriminately as battery cells and an energy storage device constructed therefrom also referred to as a battery or battery assembly), a fuel cell, a high-power capacitor or an energy storage cell of a different nature. In particular, in this context an energy storage cell is to be understood as meaning an electrochemical energy storage cell which stores energy in chemical form, delivers it in electrical form to a consumer and preferably can also receive it in electrical form from a charging device. Important examples of such electrochemical energy stores are galvanic cells and fuel cells.

An electrochemical energy storage cell preferably comprises an active region or active part in which electrochemical conversion and storage processes take place, and an enclosure for encapsulating the active part from the environment. The active part preferably has an electrode stack which is formed from an electrode arrangement of electrodes, active layers, separator layers and an electrolyte accommodated by the separator layers. The electrodes are preferably plate-shaped or foil-like and are preferably arranged substantially parallel to one another (prismatic energy storage cells). The electrode assembly may also be wound and have a substantially cylindrical shape (cylindrical energy storage cells) or have the shape of a flattened coil. The term electrode stack should also include such electrode coils. The active layers and separator layers may be at least partially provided as independent foil blanks or as coatings of the electrodes. The electrolyte of the energy storage cell preferably contains lithium ions. The sheath in this context is a device which is suitable for preventing the escape of chemicals from the electrode stack into the environment and for protecting the constituents of the electrode stack from damaging external influences. The envelope may be formed from one or more moldings and / or film-like. Next, the envelope may be formed in one or more layers. The sheath is preferably formed from a gas-tight and electrically insulating material or layer composite.

The thermally conductive layer preferably has at least one first partial layer of a thermally conductive material. A thermally conductive material in the context of the invention here is a substance whose thermal conductivity is at least 1 W / (mK), in particular at least 20 W / (mK). As a result, the thermally conductive layer can be realized in a simple manner.

It is preferred that the first part-layer comprises a metal, in particular copper, or consists of metal, in particular copper. Due to the high thermal conductivity of copper, a particularly good dissipation of the heat generated in the cell is possible. In addition, due to its favorable elasticity properties, copper is particularly well suited for safely keeping a foreign body from entering the device from the outside.

Alternatively or additionally, the first partial layer comprises carbon, in particular in the form of carbon fibers. Also in this case, a very good dissipation of heat from the cell is guaranteed. In addition, carbon fibers, especially anisotropic carbon fibers, due to their high strength and rigidity with low elongation at break are particularly well suited to prevent foreign bodies from entering the cell. This is especially true when the carbon fibers are processed into a nonwoven or have the shape of a fabric.

Alternatively or additionally, it may be provided that the first part-layer has a conductive polymer with good heat-conducting properties. By using such a polymer weight can be saved over, for example, metallic sublayers.

In a further preferred embodiment, it is provided that the thermally conductive layer has at least one second partial layer made of an electrically insulating material. The second sub-layer is preferably connected to the first sub-layer by lamination, in particular hot lamination. On the one hand, the second sub-layer ensures that heat can flow well out of the cell and, on the other hand, prevents an outside of the cell from coming into electrical contact with the container, which could result in a short-circuit. In addition, it is ensured by the at least one electrically insulating second sub-layer in many cases, that in case of penetration of a foreign body, in particular a projectile from the outside shorts between the individual electrodes of the electrode stack avoided or at least significantly reduced. This is especially true when the electrically insulating second sub-layer of the thermally conductive layer is located in each case inside, d. H. between the first sub-layer and the electrode stack.

The second partial layer preferably has an electrically insulating plastic, for example PE, PP, PET or PVC. This makes it possible to realize an electrically insulating effect in a simple and cost-effective manner.

In a further preferred embodiment, it is provided that the first thermally conductive partial layer is arranged, in particular laminated, between two second electrically insulating partial layers. In this case, the thickness of the two second partial layers is preferably substantially smaller than the thickness of the first partial layer. This ensures efficient heat conduction with simultaneous electrical insulation between electrode stack and container in a simple manner, which is particularly advantageous in terms of possible damage to the device by external foreign body action, since in the case of deformation or partial penetration of both sides electrically isolated, thermally conductive Layer a short circuit of the underlying electrode pairs is less likely.

It is also preferred that the container has a one-sided open, in particular cuboidal, hollow body, which can be closed by a lid after introduction of the electrode stack or -wickels. Preferably, the hollow body is obtained by extrusion, in particular by cold extrusion, or deep drawing of a metal sheet blank. In this way, a mechanically and chemically stable enclosure of the cell can be realized simply and cost-effectively, by means of which the heat arising in the cell can be dissipated efficiently by means of the thermally conductive layer.

In a further preferred embodiment, the electrode stack has a plurality of stack layers which each have an anode layer, a cathode layer and a separator layer located between the anode layer and the cathode layer, the individual stack layers being at least partially interconnected by lamination. Here, the individual stack layers are glued to each other at least in some areas by means of an adhesive. Preferably, the adhesive is a so-called. Hot melt adhesive, which is substantially solid at room temperature and only becomes liquid when heated and unfolds its adhesive effect. Accordingly, the stack layers are preferably glued together by pressing and / or rolling under the action of heat. By one or more of these measures, a high mechanical stability of the electrode stack is achieved, at the same time by the at least partial bonding of the stack layers they are thermally coupled together well, so that a derivative of heat generated in the cell in the direction of the thermally conductive layer or the metallic container wall is favored.

A battery arrangement has a plurality of energy storage devices according to the invention, on which contact elements are provided, which are electrically connected to each other, in particular in series and / or connected in parallel. In this way, the voltages or powers of the battery arrangement required for the respective application are realized.

The energy storage device or the battery arrangement according to the invention is advantageously used for supplying an electric drive or hybrid drive of a motor vehicle with electrical energy.

Further advantages, features and applications of the present invention will become apparent from the following description taken in conjunction with the figures. Show it:

1 an example of the construction of an energy storage device;

2 a first example of a cross section through an energy storage device;

3 a second example of a cross section through an energy storage device;

4 a first example of a cross section through a thermally conductive layer;

5 a second example of a cross section through a thermally conductive layer;

6 a section of the in 2 Example shown in the event that an object has penetrated into the container of the energy storage cell; and

7 an example of the structure of an electrode stack.

1 shows an example of the construction of an energy storage device with a substantially cuboid container 1 , which is preferably formed of metal and is open to one side. The container 1 For example, by means of extrusion, in particular cold extrusion, or deep drawing of a corresponding starting workpiece, in particular a sheet, can be produced.

Through the open side of the container 1 becomes an electrode stack 2 or an electrode coil (not shown) in the container 1 introduced. The electrode stack 2 has a plurality of juxtaposed stack layers, each comprising an anode layer, a cathode layer, and an interposed separator layer with electrolyte. The respective anode layers or cathode layers are provided with contact lugs 3 respectively. 5 electrically contacted. The contact flags 3 and 5 become with the help of further contact elements 4 respectively. 6 through an insulation element 7 through with the lid 8th the energy storage device contacted or by means of another, not shown contact elements through an opening 9 in the lid 8th passed out through the energy storage device.

At the in 2 shown first example of a cross section through an energy storage device, the two side walls and the bottom wall of the container 1 and the electrode stack 2 to recognize. Between the electrode stack 2 and the two side walls of the container 1 is in each case a thermally conductive layer 10 provided, which is designed in such a way that this heat from the electrode stack 2 in the direction of the two side walls of the container 1 can derive or forward. Heat generated during charging or discharging of the energy storage device can thereby be efficiently applied to the side walls of the container 1 be passed so that the occurrence of heat accumulation in the energy storage cell can be effectively prevented or at least greatly reduced.

The thermally conductive layers 10 are preferably on the side walls of the container 1 and at the electrode stack 2 without, however, to be connected to this or this cohesively, for example by gluing or laminating. The thermally conductive layers 10 In this case, separate layers between the container wall and the electrode stack 2 which, for example, placed on the electrode stack during assembly of the energy storage device and together with this in the container 1 be inserted. By a certain elasticity of the electrode stack 2 this view expands slightly within the container so that the between the electrode stack 2 and the container wall located thermally conductive layers 10 pressed against the container wall. To increase the elasticity and generation of defined contact forces, it may be advantageous on or in the electrode stack 2 For example, between two stack layers to provide an elastic insert.

In principle, it is also possible, the thermally conductive layers 10 with the respective outer surfaces of the electrode stack 2 and / or the respective inner surfaces of the side walls of the container 1 connect, for example by gluing and / or laminating.

At the in 3 shown second example of a cross section through an energy storage device are thermally conductive layers 10 not only in the area of the two side walls of the container 1 provided, but also in the area of the soil. Preferably, in this case, the electrode stack 2 from a thermally conductive layer formed in one piece 10 enclosed or surrounded. In this way, the in the electrode stack 2 resulting heat particularly efficient towards the outside of the container 1 the energy storage device are passed.

In this case, it is in terms of heat dissipation of additional advantage when between the electrode stack 2 and the two in the plane of the figure extending end faces of the container 1 also a corresponding thermally conductive layer 10 is introduced. For the rest, the remarks in connection with in 2 according to the example shown.

4 shows a first example of a structure of the thermally conductive layer 10 with a first sub-layer 11 from a thermally conductive material. For the purposes of the invention, thermally conductive material is to be understood as meaning substances whose thermal conductivity is greater than about 1 W / (mK). To a particularly good dissipation of heat from the electrode stack 2 In particular, substances are preferred whose heat conductivities is at least 20 W / (mK), in particular at least 100 W / (mK).

Preferably, the first partial layer is 11 a layer of metal, in particular of copper. Alternatively or additionally, however, it is also possible that the first partial layer 11 Carbon fibers, also called carbon fibers has.

The first sub-layer 11 will be in the in 4 shown example of two second sub-layers 12 . 13 included, each consisting of an electrically insulating material, such as plastic. To the heat conduction properties of the thermally conductive layer 10 To keep as large as possible, the second sub-layers 12 . 13 as thin as possible. Preferably, their layer thickness is at most 30% of the layer thickness of the first partial layer 11 , It is particularly preferred that the thickness of the second partial layers 12 . 13 less than 1/10 of the thickness of the first sub-layer 10 is.

At the in 5 shown second example of a cross section through a thermally conductive layer 10 includes these in addition to the first sub-layer 11 made of thermally conductive material, only a second sub-layer 12 made of an electrically insulating material. In this embodiment, a particularly good dissipation of heat arising in the electrode stack is ensured, which is particularly true for memory cell types in which a double-sided electrical insulation of the first sub-layer 11 is not required, leading to special benefits. With regard to the respective thicknesses of the first and second partial layers 11 respectively. 12 as well as the materials preferably to be used, the statements apply in connection with 4 corresponding.

A particular advantage of using the above-described thermally conductive layers 10 in energy storage devices also lies in the fact that the electrode stack 2 in case of mechanical damage of the container 1 From the outside much better protected against short circuits, as is the case with energy storage cells known from the prior art. This is based on 6 which has a section A from the in 2 illustrated cross section through an energy storage device, explained in more detail.

In the in 6 The case shown penetrates an object, for example a projectile 19 , the side wall of the container 1 and deforms both the immediately behind the side wall of the container 1 lying thermally conductive layer 10 as well as the underlying stack layers of the electrode stack 2 , In the case shown, the projectile 19 through the thermally conductive layer 10 prevented from further entering the energy storage device, ie the projectile 19 pierces the thermally conductive layer 10 Not. In this case, the deformation of the stack layers of the electrode stack 2 be kept so low that the individual stack layers are not severed substantially. In this way, the occurrence of short circuits in the individual stack layers is prevented and the functioning of the cell is maintained.

By in the 4 and 5 shown embodiment of the thermally conductive layer with one or two electrically insulating sub-layers 12 . 13 But even in the event that the projectile 19 also the thermally conductive layer 10 durchschlägt, the advantage that, in the case of an opening of the first stack layers of the electrode stack 2 this only with the electrically insulating second sub-layer 12 respectively. 13 the layer 10 and can not be short-circuited in this way. The operation of the energy storage cell can therefore be maintained even for this case.

7 shows a section of an exemplary structure of the electrode stack 2 which consists of a plurality of stacking layers 20 is composed. The stack layers 20 in turn each consist of an anode layer 21 , a cathode layer 22 and a separator layer between them 23 together. In the separator layer 23 is an electrolyte. Between the individual stack layers 20 is in each case an insulating layer 24 intended. The individual stack layers 20 including the insulating layer 24 are connected to each other at least in the region of a part of their contact surface, preferably by means of an adhesive. It is particularly preferred to choose an adhesive which is solid at room temperature and melts only by heating and unfolds its adhesive effect. In this case, the stacked layers provided with a corresponding adhesive become 20 connected by a so-called Heißlamination by these pressed, for example, under the action of heat and / or rolled. By the described, at least partially, connection of the individual stack layers 20 of the electrode stack 2 a particularly high mechanical stability of the stack, even and especially in the event of damage to the container 1 from the outside, like in 6 explained in more detail achieved.

Claims (14)

Energy storage device having at least one energy storage cell with an electrode stack ( 2 ) or electrode winding and a container ( 1 ) for receiving the energy storage cell, characterized in that between the energy storage cell, in particular the electrode stack ( 2 ) or electrode winding, and at least one wall of the container ( 1 ) at least one thermally conductive layer ( 10 ) is provided, by which heat from the energy storage cell, in particular in the direction of the wall of the container ( 1 ), can be derived. Energy storage device according to claim 1, wherein the thermally conductive layer ( 10 ) at least a first sub-layer ( 11 ) of a thermally conductive material. Energy storage device according to claim 2, wherein the first sub-layer ( 11 ) has a metal, in particular copper. Energy storage device according to claim 2 or 3, wherein the first sub-layer ( 11 ) Carbon, in particular in the form of carbon fibers having. Energy storage device according to one of claims 2 to 4, wherein the first sub-layer ( 11 ) comprises a conductive polymer. Energy storage device according to one of the preceding claims, wherein the thermally conductive layer ( 10 ) at least one second sub-layer ( 12 . 13 ) made of an electrically insulating material. Energy storage device according to claim 6, wherein the second sub-layer ( 12 . 13 ) has an electrically insulating plastic. Energy storage device according to claim 2 and 6, wherein the first sub-layer ( 11 ) between two second partial layers ( 12 . 13 ) is arranged. Energy storage device according to one of the preceding claims, wherein the container ( 1 ) has a one-sided open, in particular cuboid, hollow body. Energy storage device according to claim 9, wherein the hollow body is obtained by extrusion, in particular by cold extrusion, or deep drawing. Energy storage device according to claim 9 or 10, wherein the hollow body consists of metal. Energy storage device according to one of the preceding claims, wherein the electrode stack ( 2 ) several stack layers ( 20 ), each having an anode layer ( 21 ), a cathode layer ( 22 ) as well as between the anode layer ( 21 ) and the cathode layer ( 22 ) separator layer ( 23 ), wherein the individual stack layers ( 20 ) are at least partially interconnected by lamination. Battery arrangement with a plurality of energy storage devices according to one of the preceding claims, wherein provided on the energy storage devices contact elements ( 4 . 6 ) are electrically connected to each other. Use of the energy storage device according to one of claims 1 to 11 or the battery arrangement according to claim 13 for supplying an electric drive or hybrid drive of a motor vehicle with electrical energy.

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