FR2988915A3 - Module structure for housing lithium-ion battery cells in battery module in e.g. electric vehicle, has case arranged to form spacing between adjacent walls perpendicular to basic wall, where thickness of basic wall is equal to that of cells - Google Patents

Abstract

A battery module structure for accommodating flexible envelope Li-ion cells (1), comprising an extruded aluminum housing (12) and an upper cover (14), the housing (12) comprising: a bottom wall (121), - two side walls (122, 123) perpendicular to the bottom wall (121) and integral with parallel edges of the bottom wall (121), - at least one perpendicular inner wall (124) at the bottom wall (121) and integral with the latter, the upper cover (14) closing the housing on the side of the side walls (122, 123) opposite the bottom wall (121) and the housing (12) being shaped so that the spacing (e) between two adjacent walls perpendicular to the bottom wall (121) is substantially equal to the thickness of a predetermined number of cells (1). The invention also relates to a battery module comprising such a structure.

Description

The invention relates to a battery module structure for flexible envelope Li-ion cells and a corresponding battery module. BACKGROUND OF THE INVENTION Li-ion batteries are increasingly used to store energy in electric vehicles or hybrid vehicles. Several tens or hundreds of cells are used to configure a battery (or battery pack) that meets the specifications required by these automotive applications (voltage, power, energy, etc.). To facilitate the assembly of the numerous cells necessary for the production of a battery, a subassembly of several cells, called "module", is generally used. There are different module technologies depending on the structure of the cell. A Li-ion cell must avoid contact with water or moisture to maintain its life. For this purpose, a Li-ion cell is disposed in a metal container, which may be a hard, cylindrical metal housing, or a flexible prismatic aluminum shell. The hard cases are usually made of aluminum and obtained after several stamping steps, which allows for very deep parts, but have a high cost. In addition, the structure between the electrodes and the terminals can be complex and require many parts, which is also a cost. A hard metal case cell is thus advantageous in terms of strength and robustness, but has a relatively high final cost and is relatively heavy. The flexible envelopes consist of an aluminum film laminated with a plastic film electrically insulating it from the internal electrolyte. The flexible envelope cell has a very simple structure with few parts. It also has the advantage of facilitating the dissipation of heat through the thin thickness of its envelope and its large surface. Nevertheless, the cell itself does not have a rigid structure so that the assembly of several cells in a module requires the use of rigid housings, which increases the volume and the weight of the whole and reduces the efficiency. of heat dissipation. Thus, for example, the document US2009 / 0220853A1 discloses closed housings stamped aluminum each containing two Li-ion cells flexible envelope, these boxes are then grouped in a support frame. The assembly is, however, relatively complex with the first assembly of the housings with risks of play between the cells in each housing, and the assembly of the housings together to form a battery. The final number of pieces is thus relatively high, as well as the weight and the cost of production. In addition, the thermal conductivity of one module to another is limited which makes it difficult to heat / cool the cells. There is therefore a need for a module for assembling flexible envelope Li-ion cells without substantially increasing the volume and weight of the module and maintaining good thermal conductivity at the cell level. The invention aims to overcome these disadvantages by proposing a battery module structure for Li-ion cells with a flexible envelope which is simple and easy to manufacture, in particular for different numbers of cells, which is rigid, light and which makes it possible to manage easily the temperature of the cells. For this purpose, the subject of the invention relates to a battery module structure intended to accommodate Li-ion cells with a flexible envelope, characterized in that it comprises an extruded aluminum case and an upper cover, the case comprising : a bottom wall, two side walls perpendicular to the bottom wall and integral with parallel edges of the bottom wall, at least one inner wall perpendicular to the bottom wall and integral with the latter, the upper cover closing the housing of the side of the side walls opposite the bottom wall and the housing being shaped so that the spacing between two adjacent walls perpendicular to the bottom wall is substantially equal to the thickness of a predetermined number of Li-ion flexible envelope cells .

The realization of the extruded aluminum housing allows to realize in a simple and easy way a housing of precise dimensions, robust in mechanical strength and light. It is thus possible to accurately size the spacing between two adjacent walls perpendicular to the bottom so as to obtain the lowest possible clearance between these adjacent walls and the cells arranged between them. In particular, the spacing between two adjacent walls is substantially equal to the thickness of the cells housing between these walls.

The thickness of a cell is the average cell thickness provided by the manufacturer. The term "substantially" encompasses the differences in thickness that can be observed between cells of the same manufacture (representing ± the thickness of the cell), as well as the manufacturing tolerances of the housing. It also corresponds to a dimension that may be 0.1 to 0.9 mm higher or lower than the sum of the cell thicknesses disposed between adjacent walls. Preferably, the spacing will be slightly less than the sum of the thicknesses, for example from 0.1 to 0.9 mm or n times 1 to 2% of the thickness of a cell, where n is the number of cells housed between two adjacent walls. The cells are thus slightly compressed in the housing which promotes thermal conduction between the cells and the adjacent walls and contributes to increasing the life of the cells. The number of flexible envelope Li-ion cells that can be accommodated between two adjacent walls perpendicular to the bottom wall can be variable, for example from 2 to 6, preferably from 2 to 4. It is possible to house more cells between two adjacent walls. However, the higher the number of cells housed, the less the thermal conduction between the housing and the cells.

Such an extruded aluminum structure also has the advantage of having a very good thermal conduction so that it is easy to manage the temperature of the cells, in cooling and / or heating, for example by arranging a cooler (and / or a heater) along one of the walls of the structure, for example under the bottom wall or on the lid. Advantageously, the inner walls and the side walls will be identical, for example of rectangular shape. However, it is possible to envisage other shapes or to provide two identical side walls and internal walls that are identical to each other, but with slightly smaller dimensions than the side walls, for example having a smaller dimension perpendicular to the bottom wall.

Advantageously and without limitation, the housing is shaped so as to define the same spacing between each pair of two adjacent walls perpendicular to the bottom wall. The same number of cells can then be housed between each pair of adjacent walls.

Advantageously and in a nonlimiting manner, the inner faces of the bottom wall and the top cover comprise shapes shaped to the shape of the edges of the Li-ion cells with flexible envelope intended to be arranged in the housing between two adjacent walls perpendicular to the bottom wall. Due to the structure of a flexible cell, the distance between the edges of the two end cells disposed between adjacent walls is less than the thickness of the juxtaposed cells. This configuration of the bottom wall and the top cover thus makes it possible to improve the holding in position of the cells arranged between two adjacent walls. These adjusted shapes may be housings having a dimension, perpendicular to the side and internal walls, substantially equal to the distance separating the edges of the two end cells. Advantageously and in a nonlimiting manner, the module structure according to the invention comprises two plastic side covers fixed to the housing perpendicular to the side walls, the bottom wall and the top cover. These side covers thus close the lateral sides of the housing, providing protection of the ends of the cells disposed between the adjacent walls. These cell ends are those with the electrical terminals of the cells. The side covers may be arranged to fit on the housing, for example by cooperation with one or more walls of the housing. As well as the inner faces of the top cover and the bottom wall, the inner faces of the side covers may further comprise shapes shaped to the edge shape of the flexible envelope Li-ion cells disposed between two adjacent walls of the housing and thus participate in maintaining these cells in the housing.

The side covers can be attached to the housing by gluing, and / or screws, rivets or the like. Advantageously and in a nonlimiting manner, the structure according to the invention comprises electrical connection elements, such as electrical connection bars called busbars and terminal terminals, intended to electrically connect flexible-envelope Li-ion cells arranged in the housing. these connecting elements being secured to the side covers, either by fixing means or by integration with the side covers.

Advantageously and without limitation, according to one embodiment, the upper cover is separate from the housing and is arranged to fit on the housing. The upper cover can then be made of plastic or also of aluminum, especially extruded aluminum, aluminum being preferred for a more homogeneous thermal conduction in the module structure. The upper cover may in particular comprise fastening portions shaped to cooperate with the edge of the side and / or internal walls. These fixing portions may furthermore have a shape adjusted to the shape of the edge of the cells intended to be housed in the housing and thus participate in maintaining these cells in the housing. Advantageously and in a nonlimiting manner, according to another embodiment, the top cover is made of an extruded aluminum piece with the housing, which further simplifies the embodiment of the housing and the assembly of the different parts.

Advantageously and without limitation, a heating and / or cooling device may be provided integral with one or more walls of the side walls, the bottom wall, the top cover or integrated with one or more of these walls. Preferably, this heating and / or cooling device is provided integral with the bottom wall and / or the top cover or integrated with one and / or the other. This arrangement is particularly favorable because the thermal conduction propagates inside the housing by the internal or lateral walls in the direction of the bottom wall or the top cover. The invention also relates to a battery module comprising a structure according to the invention and a plurality of Li-ion cells with a flexible envelope housed in the housings of the structure defined between two adjacent walls perpendicular to the bottom wall, a set of a predetermined number of cells, for example 2 to 6 cells, being arranged in each housing. A robust and lightweight module is thus obtained, made simply with a small number of parts and ensuring good thermal conduction.

The cells mounted in the housing may be of the type comprising an electrical terminal at each end, these terminals being thus located opposite the side covers of the housing. Advantageously and in a nonlimiting manner, an electrically insulating flexible material is interposed between two adjacent cells of the same housing, this material being able to fill the gap existing between the cells, in a direction perpendicular to the internal walls. The game to be filled can be of the order of 0.1 to 0.9 or represent 1 to 2% of the thickness of a cell. This material may be a gel or silicone paste, a compressible synthetic foam or a synthetic or natural rubber sheet. Placement of this material compresses the cells, which can improve the thermal conductivity between the cells and the walls of the housing and increase the life of the cells. It is also possible to insert the cells in an unloaded state, without material to fill the gap. The tightening of the cells can then be obtained automatically after several cycles of charging / discharging due to the internal expansion of the cells. Alternatively or in addition, holding elements of electrically insulating material are inserted between the edges of adjacent cells or between the edges of a cell and the adjacent wall, these holding elements being shaped to fill a space existing between the edges of cells. adjacent or between the edge of a cell and the adjacent wall so as to block and maintain the edges of the cells. Such an arrangement makes it possible to improve the maintenance of the cells inside the housing. These holding elements will preferably have sufficient rigidity to ensure this locking and holding. They will preferably be in the form of a frame to facilitate positioning between adjacent cells or between a cell and an adjacent wall. Optionally, this frame may be integral with a sheet of flexible electrically insulating material to be inserted between two adjacent cells to fill an existing gap between the cells.

The module according to the invention has the advantage of assembling a large number of cells with few parts to assemble. This module can thus form a battery (or battery pack), unlike the modules of the prior art, a large number of which must be assembled to obtain the number of cells desired for a battery pack. The invention is now described with reference to the accompanying non-limiting drawings, in which: FIG. 1 is a perspective representation of the various elements forming a structure according to one embodiment of the invention; FIG. 2 is a side view of the structure represented in FIG. 1, without the side cover, FIG. 3 is a view from above of the structure represented in FIG. 1, the side covers being shown in section, FIG. Figure 1 is a perspective view of the casing of a structure according to another embodiment of the invention. FIG. 1 shows a structure of a battery module 10 intended to house Li-ion cells with a flexible envelope 1. This module 10 is shown assembled in FIGS. 2 and 3. As shown in FIG. The flexible envelope member 1 is formed of a flexible sheet folded and welded along its edges 2, 3, 4, 5 to form a pocket. These welded edges 2, 3, 4, 5 thus have a certain rigidity and are flat. Two electrical terminals 6, 7 protrude from the cell 1, on opposite edges 2, 4 thereof.

The structure comprises an extruded aluminum housing 12 and an upper cover 14 closing an upper opening of the housing. The housing 12 comprises: a bottom wall 121, two side walls 122, 123, perpendicular to the bottom wall 121 and integral with parallel edges of the bottom wall 121, a plurality of internal walls 124 perpendicular to the bottom wall 121 and integral of the latter.

The upper cover 14 closes the housing 12 on the side of the side walls 122, 123 opposite the bottom wall 121. Thus, when it closes the housing 12, the top cover 14 is parallel to the bottom wall 121 (Figure 2) .

The housing 12 of extruded aluminum thus formed can receive several cells 1 between two adjacent walls perpendicular to the bottom wall 121. The inner walls 124 and the side walls 122, 123 are preferably identical, for example of rectangular shape as shown. They thus define dwellings of identical shape. The spacing (e) between two adjacent walls perpendicular to the bottom wall 121 defines the number of cells 1 that a housing can accommodate (Figure 1). This spacing (e) is thus substantially equal to the thickness of a predetermined number of cells 1. A housing may thus accommodate from two to six cells, for example two cells 1 as shown in FIGS. 1 and 4. Generally, the same number of cells 1 is disposed in each housing. The housing 12 is then shaped so as to define the same spacing (e) between each pair of two adjacent walls perpendicular to the bottom wall 121, as in the examples shown. The bottom wall 121 and the top cover 14 further comprise shapes 125 and 126 respectively fitted to the shape of the edges 3, 5 of the cells 1 intended to be arranged in the housing between two adjacent walls perpendicular to the bottom wall 121. Thus, in the example, these forms 125, 126 have a dimension (perpendicular to the inner walls 124) smaller than the spacing (e) between two adjacent walls to receive the edges 3, 5 respectively of the inserted cells. As can be seen in FIG. 2, this dimension corresponds to the distance separating the edges 3 (or 5) of the two cells 1 housed between adjacent walls. The ends of the edges 3, 5 of these cells 1 can be folded to save space, as shown in Figure 2, the folded end of these edges extending parallel to the bottom wall 121 in the example. In the example shown, these shapes 125, 126 respectively of the bottom wall 121 and the cover 14 are identical.

The upper cover 14 is distinct from the housing 12 in the embodiment shown in Figures 1 to 4 and is made of extruded aluminum. It has a wall 145 of the same shape and size as the bottom wall 121.

This upper cover 14 is arranged to fit on the housing 12. For this purpose, it comprises fixing portions 141, 142, 143, 144, cooperating with the edge of the side walls 122, 123 and / or internal 124 respectively. In the example, these attachment portions 141, 142, 143, 144 are in the form of walls extending perpendicularly to the wall 145 over the entire length of the top cover 14. The end attachment portions 141 and 142 are arranged to come into contact with the upper edge of the side walls 123 and 122, respectively, when the top cover 14 is nested on the housing 12. The other fixing parts 143, 144 are arranged in pairs so as to form a space between them, space inside which can be inserted the edge of an inner wall 124, as shown in Figure 2. This arrangement ensures a good mechanical strength of the inner walls of the housing 12 on the side of their edge opposite the bottom wall 121. The adjusted shapes 125, 126 of the cover 14 are further formed on these attachment portions 141, 142, 143, 144 in the example. As a variant, these fixing parts could also be locking tabs cooperating with corresponding parts or orifices of the housing 12.

The structure also comprises two plastic side covers 16 fixed to the housing 12 perpendicular to the side walls 122, 123, the bottom wall 121 and the top cover 14. These side covers 16 thus close the lateral sides of the housing 12, ensuring a protection of the edges 2, 4 of the cells arranged between the adjacent walls, which generally bear the electrical terminals 6, 7 of the cells 1. The side covers 16 are identical and each have a wall 165 closing the lateral opening of the housing 12. side covers 16 may be arranged to fit on the housing 12, for example cooperation of suitable fixing parts. These attachment portions may furthermore have a shape fitted to the edge 2, 4 of the cells 1 housed in the housing 12.

In the example, these fastening portions have a shape similar to the shape of the attachment portions 141, 142, 143, 144 of the top cover 14. Namely, each side cover 16 has attachment portions 161, 162, 163, 164, cooperating with the edge of the side walls 122, 123 and / or internal 124 respectively, as shown only in Figure 3. In the example, these parts 161, 162, 163, 164 are in the form of walls s extending perpendicularly to the wall 165 over the entire height thereof. The end fixing portions 161 and 162 are arranged to come into contact with the side edge of the side walls 123 and 122, respectively, when the side cover 16 is nested on the housing 12. The other parts 163, 164 are arranged in pairs so as to form a space between them two by two, space within which can be inserted the edge of an inner wall 124, as shown in Figure 3. The side covers 16 may further be attached to case by gluing and / or by screws, rivets or the like. Electrical connection bars 18, also called busbars, for electrically connecting cells 1 are arranged in the housing 12. In the example, the side covers 16 have openings 166 for the passage of the terminals 6, 7 of the cells 1. The connecting bars 18 are then connected to the edges 6, 7 through the openings 166 and are disposed between the openings 166 of the side covers 16, on the outer face of the covers.

These electrical connection bars 18 are optionally secured to the side covers 16 or integrated in the side covers 16 (not shown). Figure 3 shows eight cells 1, two cells being disposed between two adjacent walls. The cells arranged between two adjacent walls are connected in parallel with each other via their electrical terminals 6, 7, these four pairs of cells 1 being connected in series via the electrical connection bars 18, terminal terminals 19, 20 being connected to the electrical terminals pairs of cells 1 adjacent the side walls 122, 123. Of course, other connection schemes between the cells 1 can be made. External covers 22 placed over the side covers 16 (FIG. 3) make it possible to protect the various connection elements 18, 19, 20. As a variant, these connection elements can be arranged between the lateral covers 16 and the housing 12. It is then not necessary to provide protective covers. The embodiment shown in FIG. 5 differs from that shown in FIGS. 1 to 4 only in that the upper cover is made of an extruded aluminum part with the housing 12, thus forming a wall 127 parallel to the bottom wall 121 and secured to the side walls 122, 123 and internal walls 124. The cells 1 are put in place as follows in the housing shown in Figures 1-4. The cells 1 are arranged in pairs between two adjacent walls, as shown in FIG. 4, their electrical terminals 6, 7 being located on lateral sides of the housing 12 so as to be protected by the side covers 16. These cells 1 can be inserted in the unloaded state so that, even if a clearance remains between the cells and the adjacent walls, this game is filled after several charging / discharging cycles. In the example shown in FIG. 4, these cells 1 are held at their edges 2, 3, 4, 5 by holding elements 24 of electrically insulating material. These holding elements 24 are frames shaped to be able to be placed against the edges 2, 3, 4, 5 of the cells 1 and fill the space between the edges 2, 3, 4, 5 of adjacent cells 1, as visible on FIGS. 2 and 3. These holding elements 24 are thus positioned between the cells 1 before they are placed between adjacent walls of the housing 12, as shown in FIG. 4. These holding elements 24 are for example made of plastic rigid enough to maintain the edges of the cells. A silicone gel or paste, a compressible synthetic foam or a synthetic or natural rubber sheet can also be inserted between the cells 1 (preferably before they are inserted between the adjacent walls) in order to improve their maintenance between the adjacent walls by filling the game possibly present. When all the cells 1 are in place, the upper cover 14 and the lateral covers 16 are secured to the housing 12 and the electrical connections between the terminals 6, 7 of each cell 1 and the electrical connection bars 18 and the terminal terminals 18, 19 are realized. These connections can be protected by covers 22. The module 10 thus obtained can thus be easily and quickly mounted and form a battery pack.

Claims (1)

REVENDICATIONS1. A battery module structure (10) for accommodating soft shell Li-ion cells (1), characterized in that it comprises an extruded aluminum housing (12) and an upper cover (14), the housing (12) ) comprising: a bottom wall (121), two side walls (122, 123) perpendicular to the bottom wall (121) and integral with parallel edges of the bottom wall (121), at least one inner wall (124) perpendicular to and secured to the bottom wall (121), the top cover (14) closing the side side housing (122, 123) opposite the bottom wall (121) and the housing (12) being shaped so that the spacing (e) between two adjacent walls perpendicular to the bottom wall (121) is substantially equal to the thickness of a predetermined number of cells (1) Li-ion flexible envelope. Structure according to claim 1, characterized in that the housing (12) is shaped to define the same spacing (e) between each pair of two adjacent walls perpendicular to the bottom wall (121). any one of claims 1 or 2, characterized in that the inner faces of the bottom wall (121) and the top cover (14) comprise shapes (125, 126) adjusted to the shape of the edges of the cells (1). Li-ion flexible envelope intended to be arranged in the housing between two adjacent walls perpendicular to the bottom wall (121) 4. Structure according to any one of claims 1 to 3, characterized in that it comprises two side covers (16) of plastic fixed to the housing (12) perpendicular to the side walls (122, 123), the bottom wall (121) and the top cover (14) 5. Structure according to claim 4, characterized in that what she understands electrical connection members (18, 19, 20) for electrically connecting flexible-shell Li-ion cells (1) disposed in the housing (12), said connecting elements (18) being secured to the side covers (16). 6. Structure according to any one of claims 1 to 5, characterized in that the upper cover (14) is separate from the housing (12) and is arranged to fit on the housing (12). 7. Structure according to any one of claims 1 to 5, characterized in that the upper cover (14) is made of an extruded aluminum part with the housing (12). 8. Structure according to any one of claims 1 to 7, characterized in that a heating and / or cooling device is integral with one or more walls of the side walls (122, 123), the bottom wall ( 121), the top cover (14) or integrated with one or more of these walls. 9. Module (10) battery comprising a structure (10) according to one of claims 1 to 8 and a plurality of cells (1) Li-ion flexible envelope housed in the housing of the structure defined between two perpendicular adjacent walls at the bottom wall (121), an assembly of a predetermined number of cells (1) being disposed in each housing. 10. Module (10) battery according to claim 9, characterized in that an electrically insulating flexible material is interposed between two adjacent cells (1) of the same housing, this material being able to fill a game existing between the cells. (1) and / or that holding elements (24) of electrically insulating material are inserted between the edges of adjacent cells (1) or between the edges of a cell (1) and an adjacent wall, these elements of holding (24) being shaped to fill an existing space between the edges of adjacent cells or between the edge of a cell and the adjacent wall so as to block and maintain the edges of the cells (1).