Patent Description:
When battery cells are charged and discharged heat is generated, which may have to be removed. For example, this is the case for battery cells in electric vehicles, where the charging and discharging may take place rather fast. To extend the lifetime and to improve the performance of battery cells, it may be beneficial to provide cooling means that go beyond a pure air cooling of an outside of the battery cells.

<CIT> shows a cooling plate for batteries, in which channels are formed between two substrates.

<CIT> shows a battery cell cooler that is formed of complementary plates, between which cooling channels are formed.

<CIT> shows a battery cell arrangement with cooling plates between adjacent battery cells that are liquid cooled on a top edge.

<CIT> shows a battery module with several battery cells, between which a cooling element is arranged. The cooling element has a channel, which is covered by a foil.

<CIT> describes a heat-exchanging pouch, which is arranged between battery cells. The pouch is made of two foils and webs between the foils.

<CIT> shows a heat exchanger for a battery, which has a fluid transfer layer <NUM>, which is covered by two graphite foils <NUM>.

<CIT> shows in a cooling structure to be inserted between two prismatic batteries with a cooling channel that is covered by a foil.

It is an objective of the invention to improve the cooling of battery cells.

This objective is achieved by the subject-matter of the independent claims. Further exemplary embodiments are evident from the dependent claims and the following description.

The invention relates to a battery cell arrangement. A battery cell arrangement may comprise a plurality of battery cells, in particular pouch cells, which may be connected in series and/or in parallel. The battery cell arrangement may furthermore comprise a housing and/or support member, which mechanically interconnects the pouch cells, which, for example, may be arranged one after the other in a stack.

The battery cell arrangement may be used as electrical energy storage of any mobile device e.g. an electric vehicle or any stationary application. However, it is also possible that the battery cell arrangement is used in other applications.

According to an embodiment of the invention, the battery cell arrangement comprises at least two pouch cells and a support frame arranged between the two pouch cells, wherein the support frame has a cooling frame sandwiched between the pouch cells.

A pouch cell may be an electrochemical cell with two electrodes and an electrolyte inside a pouch, which may be seen as a flexible bag. The electrodes may be foil based. Also the terminals of the pouch cell, which may protrude from a side of the pouch cell, may be made of foil and/or may be flexible.

It may be that the battery cell arrangement comprises a plurality of pouch cells, which are stacked in a stacking direction. Between two adjacent pouch cells, a support frame may be arranged, i.e. the pouch cells and the support frames may be arranged alternating one after the other in the stacking direction. The pouch cells may be arranged in such a way that their terminals all protrude from one side of the battery cell arrangement.

It has to be noted that an extension of the pouch cells and the support frame in between them in directions orthogonal to the stacking direction may be much larger (such as <NUM> times larger) as in the stacking direction.

The support frame, which may be made of plastics, such as a polymer, may have an inner part, i.e. the cooling frame or cooling plate or cooling fluid circulating channel, which may be in direct thermal contact with the pouches of the pouch cells. Direct thermal contact may mean that the cooling frame and the pouch are in mechanical contact, such that heat from the one component may flow to the other one via a contact area. The cooling frame may be a substantially flat and/or plate like part of the support frame, which may have two flat faces facing the pouches of the adjacent pouch cells. The cooling frame may be in two-dimensional contact with the facing sides of the adjacent pouch cells.

According to an embodiment of the invention, the cooling frame has a cooling channel running through the cooling frame between an outlet and an inlet, wherein the cooling channel is covered by a foil attached to the cooling frame for forming a tubular, for example meandering, passage through the cooling frame. The foil, which may be seen as a membrane, may seal a cooling fluid volume inside the cooling frame from the pouch cells. In such a way, the adjacent pouch cells may be directly liquid cooled with a cooling fluid running through the cooling channel.

In general, a foil may be a sheet and/or plate of plastics and/or metal, which is thin and flexible. For example, thinner than <NUM>. The foil may be made of a different material as the support frame and/or the cooling frame. The foil may be made of a multilayer structure consisting multiple single layers of different materials.

A tubular passage may be a cavity, which is formed as a pipe or tube and/or which allows a fluid flow through it from one end to the other without a loss of fluid between the ends to an outside.

The foil may be welded to the cooling frame. For example, a polymeric welding process may be used to realize a sealing between the cooling frame and the foil. Alternatively or additionally, it may be clamped and/or sealed by flat or conventional sealing rings. The foil may be made of an electrical isolating material, such as a polyimide and/or Kapton ©. In such a way, a discharge of the battery cells into the cooling fluid may be avoided.

The cooling channel may be a longitudinal groove and/or opening in the cooling frame, which is covered by the foil. In such a way, a tubular passage may be formed, which runs through the cooling frame in a direction substantially orthogonal to the stacking direction of the pouch cells.

It may be that the cooling channel meanders through the cooling frame. The term "meandering" may mean that the cooling channel and/or the tubular passage may change its direction in the cooling frame several times. For example, the cooling channel and/or the tubular passage may have at least three substantially parallel sections, which may be interconnected with curved sections. These sections may be separated from one another by a weld of the foil to the cooling frame.

Within the meandering section, the foil may be welded to the cooling frame. The foil may only be edge welded to the cooling frame and the meandering structure may be only provided by a compressible member between the foil and the cooling frame. Multiple edge sealings may avoid leakage of cooling fluid. To increase safety, the intermediate section between two sealings may be equipped with electrical contacts, which may trigger an alarm in case of leakage of the inner sealing.

The foil may be flexible, i.e. may be as thin that it may be deformed under different pressure applied by the cooling fluid and/or the pouch of the pouch cell. For example, the foil may be thinner as <NUM>. With a foil on the cooling channel, a pouch cell compression may be adjusted by adjusting a cooling fluid pressure. The cooling system providing the cooling fluid may have a pressure compensation function, which may rise the pressure of the cooling fluid, when the pressure inside the pouch cells rises, which may be the case, when the pouch cells are charged or discharged. This may allow for a uniform side pressure to the one or more pouches in contact with the cooling frame. Furthermore, pouch cell thickness manufacturing tolerances may be compensated.

In general, by compensating pressure differences between the pouch and the cooling frame, a thermally optimized contact for the pouch cells may be provided, which may improve the cooling abilities of the battery cell arrangement.

According to an embodiment of the invention, a pouch of one of the pouch cells lies on the foil. The pouch also may be made of a foil. This foil and the foil on the cooling frame may be in direct contact. In such a way, pressure changes in the pouch cells may be directly applied to the foil on the cooling channel and vice versa.

According to an embodiment of the invention, a compressible member is attached to the cooling frame besides the cooling channel. The compressible member may be made of rubber. For example, such a compressible member may be provided between sections of the cooling channel. The compressible member also may be used for compensating pressure changes in the pouch cell and/or for compensating pouch cell manufacturing tolerances.

According to an embodiment of the invention, the foil is attached to the compressible member. For example, the compressible member and the foil may be welded to the cooling frame or just positioned onto the cooling frame without welding.

According to an embodiment of the invention, the compressible member covers the cooling frame completely between sections of the cooling channel. The area of the cooling frame between sections of the cooling channel and/or adjacent to the cooling channel may be covered with the compressible member. The compressible member may be made of a sheet from which the shape of the cooling channels has been removed and/or cut out. In such a way, a comparable large area of the pouch may lie on the compressible member.

According to an embodiment of the invention, at least a section of the cooling channel extend completely through the cooling frame in a stacking direction of the pouch cells. In this case, the cooling channel may be covered on both sides of the cooling frame by a foil. It may be that one single cooling channel is provided between two adjacent cells. The cooling channel may be a through hole in the cooling frame, which is covered on both sides of the cooling frame with a foil.

According to an embodiment of the invention, at least a section of the cooling channel extends only partially through the cooling frame in a stacking direction of the pouch cells. It may be that the cooling channel is a groove in the cooling frame, which groove is covered by the foil. For example, only one pouch cell of the two pouch cells sandwiching the support frame may be cooled by the cooling channel. The other pouch cell may be cooled by the next support frame. In this way, pouch cells may be thermally decoupled.

According to an embodiment of the invention, the cooling frame comprises two cooling channels, each cooling channel provided on one side of the cooling frame and each cooling channel extending only partially through the cooling frame. It may be that every pouch cell on each side of the cooling frame has a cooling channel of its own. This may be realized by cooling channels, which are provided as grooves on different sides of the cooling frame. It may be that the cooling channels are aligned mirror symmetric with respect to a middle plane of the cooling frame.

According to an embodiment of the invention, the two cooling channels are separated by a thermally isolating material provided in the support frame. This is a further possibility of thermally decoupling the pouch cells adjacent to the cooling frame. This may provide a thermal runaway protection by the thermally insulating material. The thermally insulating material may be provided between the cooling channels, which may separate different flow fields of cooling fluid of adjacent pouch cells. The thermally insulating material may be or may comprise a glass fiber mat or equally thermal insulating material or a combination of multiple thermal insulating layers.

According to an embodiment of the invention, a pouch cell is mechanically supported by two adjacent support frames, which clamp a border of the pouch cell between them. The support frame between two pouch cells may have a border, which is thicker than the cooling frame in the stacking direction. The support frame may mechanically support the pouch cell at a circumferential border. The pouch of the pouch cell may be made of two foils, which are welded together at their border. This border may be clamped by the support frames. For example, the support frame may have a rectangular shape. Each of the support frames may have a cooling channel as described in the above and in the following.

According to an embodiment of the invention, the support frame has a border that is thicker than the cooling frame. In such a way, a volume is provided between adjacent support frames, which is adapted for accommodating a pouch of a pouch cell.

According to an embodiment of the invention, the outlet and the inlet are provided in a border of the support frame, such that outlets and inlets of adjacent support frames are overlapping each other. Each of the inlet and/or the outlet of the cooling channel may be provided by a through hole in a border of the support frame. This through hole may extend in the stacking direction through the border. When the inlets (and/or outlets) of adjacent support frames are aligned with each other, an inlet (and/or outlet) of the battery cell arrangement is provided, to which the cooling channels are all connected in parallel. This distribution piping may be included in the support frame and/or may be attached to the support frame by a separate pipe or piping system.

According to an embodiment of the invention, electrical contacts for detecting a leak are provided in a sealing area surrounding the inlet and/or the outlet. This sealing are may be provided as two redundant sealings, for example in the form of two rings. The electrical contacts for leakage detection may be provided between the redundant sealings.

According to an embodiment of the invention, the support frame has a terminal cooling channel in a border below an electrical terminal interconnection, which is interconnecting two terminals of adjacent pouch cells. The pouch cooling channel in the cooling frame may be connected to a terminal cooling channel in the border of the support frame, for example in series or in parallel. The terminal cooling channel may be used for cooling terminals of adjacent pouch cells, which are connected with each other, for example for connecting the pouch cells electrically in series and/or in parallel.

In general, the terminal cooling channel may be hydraulically connected in series or in parallel or may be hydraulically fully independent to the pouch cooling channel.

The terminals or tabs of the pouch cells may have a good thermal conductivity to the inside of the battery cell. This thermal conductivity may be better than a thermal resistance from the center of the pouch cell to the cooling channel in the cooling frame. With the terminal cooling channel, the pouch cell additionally may be cooled via its terminals.

For example, a terminal of a pouch cell and a terminal of an adjacent pouch cell may be bent towards each other over the border of the support frame and/or may be interconnected there with each other, for example by welding. The terminal interconnection formed by the two bent terminals may lie on the border of the support frame on the terminal cooling channel.

According to an embodiment of the invention, a thermally conducting insert may be provided in the border between the terminal cooling channel and the terminal interconnection. The insert may be a metal plate that is inserted into the border of the support frame, which may be made of plastics material. The thermally conducting insert may improve the heat transfer between the terminal interconnection and the terminal cooling channel.

According to an embodiment of the invention, the terminal cooling channel is formed as tubular passage within the border of the support frame. In other words, the terminal cooling channel need not be formed by a groove covered by foil. It may be that the terminal cooling channel is wider in a stacking direction of the pouch cells than the cooling channel in the cooling frame. This may increase the effective area for heat transfer between the terminal interconnection and the terminal cooling channel. Since the border of the support frame may be wider than the cooling frame in stacking direction, there also may be space for a wider terminal cooling channel.

According to an embodiment of the invention, the foil is sealed to the cooling frame with two separate sealings. These sealings may be two welds and/or may surround the cooling channel. The sealings may be provided as inner sealing and outer sealing. Electrical contacts for detecting a leak may be provided between the sealings. A void may be present between the sealings and non-contacting electrical contacts may be positioned in the void. This may allow detect leaking cooling fluid before it leaks the outer redundant sealing.

According to an embodiment of the invention, the battery cell arrangement further comprises at least three pouch cells stacked along a stacking direction, wherein between two adjacent pouch cells, a support frame with a cooling channel covered by a foil is arranged. The battery cell arrangement may be composed of a stack of pouch cells, which are arranged alternating with support frames as described in the above and in the following. It has to be noted that the stack of pouch cells may be clamped between two termination members, such that the pouch cells and support frames are pressed against each other.

The subject-matter of the invention will be explained in more detail in the following text with reference to exemplary embodiments which are illustrated in the attached drawings.

<FIG> schematically show a pouch cell <NUM> from the front and from the side. The pouch cell <NUM> has a substantially rectangular pouch <NUM>, which may be made of two foils, which are attached together at a border <NUM> of the pouch cell <NUM>, for example by welding. The pouch cell <NUM> has two terminals or taps <NUM>, which protrude from a top side of the pouch cell <NUM>. Each terminal <NUM>, which may be made of an electrically conducting foil or a thin metal strip, is electrically connected to an electrode inside the pouch <NUM>, which also accommodates an electrolyte.

<FIG> show a battery cell arrangement <NUM> comprising three pouch cells <NUM> and two support frames <NUM> sandwiched between them. It can be seen that the border <NUM> of each pouch cell is clamped between two adjacent support frames <NUM>. The pouch cells <NUM> and support frames <NUM> are stacked in a stacking direction S. It has to be understood that a battery cell arrangement <NUM> may comprise a plurality of such pouch cells <NUM> and support frames <NUM> that may be stacked alternating with respect to each other.

For electrically connecting adjacent pouch cells <NUM>, terminals <NUM> of these pouch cells are bent towards each other and interconnected with each other, for example by welding.

<FIG> shows a cross-sectional view of an embodiment of a battery cell arrangement <NUM> along the plane A-A in <FIG>. <FIG> shows the detail B of <FIG>. <FIG> shows a cross-sectional view along the plane C-C in <FIG>.

The two support frames <NUM> have a border <NUM>, which may have substantially the same shape as the border <NUM> of the pouch cell <NUM>. Here, the borders <NUM>, <NUM> are rectangular, but other shapes also may be possible. Within the border <NUM>, each support frame <NUM> has a cooling frame <NUM>. In the stacking direction S, the border <NUM> may be thicker as the cooling frame <NUM>. In such a way, a cavity is formed between two adjacent support frames <NUM>, which accommodate the pouch <NUM> of the pouch cell <NUM> clamped between them.

As better seen in <FIG>, the cooling frame <NUM> comprises a cooling channel <NUM>, which runs through the cooling frame <NUM> from an inlet <NUM> to an outlet <NUM>. The cooling channel <NUM> may be aligned in a plane substantially orthogonal to the stacking direction S. The cooling channel <NUM> meanders through the cooling frame <NUM>. It has several straight sections running in different directions, which are interconnected by curved sections.

The cooling channel <NUM> in <FIG> is provided as a through-hole, i.e. it extends completely through the cooling frame <NUM> in the stacking direction S. In such a way, both sides of the cooling frame <NUM> may be cooled by one cooling channel <NUM>.

On each side of the cooling frame <NUM>, a foil <NUM> is attached, which covers the cooling channel <NUM>. In such a way, a tubular passage is formed through the cooling frame <NUM>. The foil <NUM> prevents a flow of cooling fluid outside of the cooling channel <NUM>. Furthermore, since the foil <NUM> is flexible, it allows a pressure equalization between the cooling channel <NUM> and the respective pouch <NUM>. The foil <NUM> may cover the complete area of the cooling frame <NUM>, which comes into contact with the cooling frame <NUM>.

It is possible that a compressible member <NUM> is provided between at least parts of the surface of the cooling frame <NUM> and the foil <NUM>. The compressible member <NUM>, which may be made of rubber, may be used for adjusting tolerances of the cooling frame <NUM> and/or the pouch cell <NUM>.

As indicated in <FIG>, the foil <NUM> may be sealed to the cooling frame <NUM> at least at the border of the cooling frame <NUM> with one or more sealings <NUM>, which may be weld lines and/or gluing lines. The sealings <NUM> between the foil <NUM> and the cooling frame <NUM> may be redundant. For example, there may be more than one sealing <NUM>.

Electrical contacts <NUM> for detecting a leak are provided between the sealings <NUM>. Equipping the area between the two redundant sealings <NUM> with electrical contacts <NUM> placed at a certain distance from each other may allow to detect leaking cooling fluid in the void between the redundant seals <NUM>. The electrical contacts <NUM> may be included in the cooling frame <NUM> and/or in the foil <NUM>.

The foil <NUM> also may be welded onto the compressible member <NUM>, which may be welded onto the cooling frame <NUM>. However, it is also possible that the compressible member <NUM> is glued onto the cooling frame <NUM> and/or that the foil <NUM> is glued or positioned onto the compressible member <NUM>.

<FIG> shows that the inlet <NUM> and the outlet <NUM> may be provided in the border <NUM> of the support frame <NUM> as through holes. The inlets <NUM> and the outlets <NUM> of adjacent support frames <NUM> may cover each other to form an inlet channel and outlet channel of the battery cell arrangement <NUM>.

As shown in <FIG>, a sealing area <NUM> may be provided between adjacent inlets <NUM> and/or outlets <NUM>, which surrounds the adjacent inlets <NUM> and/or outlets <NUM>. Electrical contacts <NUM> for detecting a leak may be provided in the sealing area <NUM>.

<FIG> shows a cross-sectional view of an embodiment of a battery cell arrangement <NUM> along the plane A-A in <FIG>. <FIG> shows the detail D of <FIG>. <FIG> shows a cross-sectional view along the plane E-E in <FIG>.

<FIG> shows that a terminal cooling channel <NUM> may be provided in the border <NUM> of the support frame <NUM>. The terminal cooling channel <NUM> may be formed as a tubular passage with the material of the border <NUM> of the support frame <NUM>. Furthermore, the terminal cooling channel <NUM> may be wider as the cooling channel <NUM> in the cooling frame <NUM> in stacking direction S.

The terminal cooling channel <NUM> is provided below an electrical terminal interconnection <NUM>, which is interconnecting the two terminals <NUM> of the adjacent pouch cells <NUM>. The terminal interconnection is formed of the two terminals <NUM>, which are bent towards each other onto the border <NUM>.

The terminal interconnection <NUM> and/or the terminals <NUM> may be attached to an insert <NUM> provided in the border <NUM>. For example, the terminals <NUM> may be welded together and to the insert <NUM>. The insert <NUM>, which is provided between the terminal cooling channel <NUM> and the terminal interconnection <NUM> may be made of metal and/or may be embedded into the border <NUM>. The insert <NUM> may improve conditions under welding and/or may spread the heat to the support frame <NUM>. Alternatively, the insert <NUM> may be omitted and the terminals <NUM> may be pressed to the support frame <NUM>.

<FIG> shows that the terminal cooling channel <NUM> may be series-connected with the pouch cooling channel <NUM> between the inlet <NUM> and the outlet <NUM>. Furthermore, <FIG> shows that the inlet <NUM> and the outlet <NUM> may be provided at different sides of the support frame <NUM>.

<FIG> shows a cross-sectional view of an embodiment of a battery cell arrangement <NUM> along the plane A-A in <FIG>. <FIG> shows the detail F of <FIG>. The cross-sectional view along the plane C-C in <FIG> may be as shown in <FIG>.

<FIG> shows a support frame <NUM> with two cooling channels <NUM> on each side with respect to the stacking direction S. Both cooling channels <NUM> may be connected in parallel via the inlet <NUM> and the outlet <NUM>, however, may not be interconnected within the cooling frame <NUM>.

The cooling channels <NUM> are formed as grooves and do not protrude through the cooling frame <NUM>. Both cooling channels <NUM> are covered by a foil <NUM> as described with respect to the previous figures. A thermally isolating material <NUM>, such as a glass fibre mat, is arranged between the cooling channels <NUM>. The thermally isolating material <NUM> may be provided through the cooling frame <NUM> and optionally may extend in the border <NUM> of the support frame <NUM>.

It has to be noted that the terminal cooling channel <NUM> as described with respect to <FIG> may be combined with the support frame <NUM> of <FIG> having a double cooling channel <NUM>.

Claim 1:
A battery cell arrangement (<NUM>), comprising:
at least three pouch cells (<NUM>) stacked along a stacking direction (S), wherein each pouch cell (<NUM>) is made of two foils, which are welded together at a border (<NUM>) of the pouch cell (<NUM>);
a support frame (<NUM>) arranged between adjacent pouch cells (<NUM>), the support frame (<NUM>) having a cooling frame (<NUM>) sandwiched between the pouch cells (<NUM>) and the support frame (<NUM>) having a border (<NUM>) that is thicker than the cooling frame (<NUM>) in the stacking direction (S);
wherein the cooling frame (<NUM>) is a flat and/or plate like part of the support frame (<NUM>), which has two flat faces facing pouches (<NUM>) of the adjacent pouch cells (<NUM>);
wherein the cooling frame (<NUM>) has a cooling channel (<NUM>) running through the cooling frame (<NUM>) between an outlet (<NUM>) and an inlet (<NUM>);
wherein the cooling channel (<NUM>) is covered by a foil (<NUM>) attached to the cooling frame (<NUM>) for forming a tubular passage through the cooling frame (<NUM>);
wherein a pouch cell (<NUM>) is mechanically supported at the circumferential border (<NUM>) by two adjacent support frames (<NUM>), which clamp the border (<NUM>) of the pouch cell (<NUM>) between them;
wherein a pouch (<NUM>) of one of the pouch cells (<NUM>) lies on the foil (<NUM>) attached to the cooling frame (<NUM>).