Battery module

Abstract

To provide a battery module in which pressure is uniformly applied to the entire surfaces of battery cells, and no load is applied due to expansion during charging.SOLUTION: A battery module 10 (10B) comprises: a pressurized container 1 filled with a pressure medium 2; and a cell laminate 30 stored in the pressurized container 1 and having a plurality of battery cells 3 laminated therein. The cell laminate 30 has holding materials 4 that are each arranged between the laminated battery cells 3 and between the outermost battery cell 3 and an inner wall of the pressurized container 1, and hold the lamination state of the cell laminate 30. The holding materials 4 are formed of a porous body having elasticity.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a battery module. [Background technology]

[0002] Conventionally, a widely known battery module involves stacking multiple laminated batteries enclosed in a laminate film and applying pressure from the top and bottom of the stacking direction to minimize the resistance distribution within the electrodes and ensure uniform reactions. However, this method of uniaxially constraining the batteries from the top and bottom results in insufficient uniformity of the reactions, resulting in poor initial characteristics and durability of the battery module, as well as reduced yields. To address these issues, it was necessary to increase the pressure-restricting force of the battery module, which tended to result in bulky exterior components for the constraints.

[0003] On the other hand, a liquid-immersed pressurized container that does not use such a restraining exterior has been proposed (see Patent Document 1). The pressurized oil and pouch cells (laminated batteries) in Patent Document 1 are stored in a sealed pressurized container, and the pouch cells are surrounded by pressurized oil to maintain a pressurized state, and restraining pressure is applied not only uniaxially on the top and bottom surfaces but also from all directions. In addition, multiple pouch cells can be stacked to form an array group. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-511920 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when multiple pouch cells are stacked, the thickness of the battery changes depending on the charging rate, which can cause misalignment between the pouch cells. To address this issue, a method is known in which a holding material is placed between the pouch cells to prevent them from moving. Therefore, when storing a solid-state battery module made up of stacked pouch cells in the liquid-immersed pressurized container described in Patent Document 1, the configuration of these holding materials becomes an issue.

[0006] For example, if a soft holding material is used, the holding material itself will be crushed by the pressure inside the container, creating a gap between the laminated battery (pouch cell) and the holding material, resulting in the problem of the laminated batteries being misaligned. Conversely, if a hard holding material is used, the holding material will adhere to the surface of the laminated battery, preventing the pressurized oil (pressure medium) from contacting the laminated battery, resulting in the problem of the laminated battery not being pressurized by the pressure medium. Furthermore, because a hard holding material cannot deform, there is also the problem that when the battery expands during charging, a load is placed on the laminated battery, the holding material, and the pressurized container.

[0007] An object of the present invention is to provide a battery module in which pressure is applied uniformly across the entire surface of the battery cells and no load is applied due to expansion during charging. [Means for solving the problem]

[0008] (1) A battery module of the present invention (e.g., battery modules 10 and 10B described below) comprises a pressurized container (e.g., pressurized container 1 described below) filled with a pressure medium (e.g., liquid 2 described below), and a cell stack (e.g., laminated battery stack 30 described below) housed within the pressurized container and comprising a plurality of stacked battery cells (e.g., laminated battery 3 described below). The cell stack has retaining materials (e.g., retaining material 4 described below) disposed between the stacked battery cells and between the outermost battery cell and the inner wall of the pressurized container to maintain the stacked state of the cell stack, and the retaining materials are made of an elastic porous material.

[0009] The cell stack is housed in a pressure vessel filled with a pressure medium, allowing the entire surface of the battery cells to be uniformly pressurized. Furthermore, by disposing a retaining material between the battery cells and between the outermost battery cell and the inner wall of the pressure vessel, the battery cells are prevented from shifting in a direction opposite to the stacking direction, thereby maintaining the stacked state of the cell stack. Furthermore, because the retaining material is an elastic porous material, when the thickness of the battery cells changes during charging, the retaining material compresses and expands in response to the expansion and contraction of the battery cells. This allows the battery module to maintain uniform response without changing the position of the battery cells, and improves durability. Furthermore, the elasticity of the retaining material allows uniform pressure to be applied to the cell stack without applying load to the pressure vessel, the cell stack, or the retaining material.

[0010] (2) The retaining material of the present invention is made of a porous body having interconnected pores, and the interconnected pores are filled with a pressure medium.

[0011] When the retaining material is an open-pore body having through-holes, the pressure medium is sufficiently impregnated into the through-holes, and uniform pressure can be maintained on the cell stack in a more preferable state.

[0012] (3) The porosity of the retaining material of the present invention is 20% or more and 50% or less.

[0013] When the porosity of the holding material is between 20% and 50%, the holding material has sufficient elasticity and can flexibly deform in response to the expansion and contraction of the battery cells.

[0014] (4) The retaining material of the present invention has a compressibility of 20% or more and 50% or less.

[0015] When the compressibility of the retaining material is between 20% and 50%, the retaining material does not deform when pressure is applied from the pressure medium, but can flexibly deform in response to the expansion of the battery cells.

[0016] (5) The holding material of the present invention has a holding force of 0.2 MPa or more and 0.5 MPa or less.

[0017] By setting the holding force of the holding material to 0.2 MPa or more and 0.5 MPa or less, it is possible to prevent the battery cells from shifting and moving in the direction opposite to the compression direction, and it is possible to more significantly maintain the stacked state of the cell stack.

[0018] (6) The retaining material of the present invention is a porous body in which the partition walls have a circular cross section.

[0019] By forming the partition walls constituting the support material to have a circular cross section, it is possible to form a porous body that allows the support material to be impregnated with a sufficient amount of solvent.

[0020] (7) The retaining material of the present invention is a porous body in which the partition walls have a corrugated cross section.

[0021] By forming the partition walls constituting the support material in a corrugated cross section, it is possible to form a porous body that allows the support material to be impregnated with a sufficient amount of solvent.

[0022] (8) The battery cell of the present invention is an all-solid-state battery cell.

[0023] In an all-solid-state battery, maintaining uniform pressure from the pressure medium is an important issue, and therefore, by using the present invention, a favorable effect can be achieved. [Effects of the Invention]

[0024] According to the present invention, a battery module can be provided which has a cell stack in which battery cells are stacked, in which the entire surfaces of the battery cells are uniformly pressurized by a pressure medium filled in a pressure container, and which has a holding material that can maintain the stacked state of the cell stack without changing the positions of the battery cells, and which can maintain uniform pressure on the cell stack during charging without applying load to the pressure container, the cell stack, or the holding material. [Brief explanation of the drawings]

[0025] [Figure 1]FIG. 1 is a schematic diagram showing a battery module according to a first embodiment. [Figure 2] FIG. 2 is an enlarged schematic view showing a battery module according to the first embodiment. [Figure 3] FIG. 3 is an enlarged schematic view showing the state in which the laminated battery of FIG. 2 is expanded. [Figure 4] FIG. 6 is an enlarged schematic view showing a battery module according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0026] [First embodiment] A first embodiment of the present invention will be described in detail below with reference to the drawings.

[0027] In the drawings of the present invention, three predetermined mutually orthogonal directions are represented by an XYZ Cartesian coordinate system. The "X direction" indicates the width direction of the solid-state battery module 10, the "Y direction" indicates the length direction of the solid-state battery module 10, the "Z direction" indicates the height direction of the solid-state battery module 10, and the "L direction" indicates the stacking direction of the laminated-type batteries 3.

[0028] FIG. 1 is a schematic diagram showing the entire battery module 10 according to the first embodiment as viewed from the Y direction. As shown in FIG. 1, the solid-state battery module 10 includes a pressurized container 1, a liquid 2, a laminated battery stack 30, and a retaining material 4. The pressurized container 1 is used with a body and a lid (not shown) sealed to form an enclosed space inside. The pressurized container 1 may be made of any material that can maintain the pressurized state of the liquid 2, and may be made of, for example, a metal such as aluminum or stainless steel, or a resin.

[0029] The liquid 2 is filled in the pressurized container 1 and pressurized by a pressurizing unit (not shown). A pressurizing pump, for example, can be used as the pressurizing unit, but the pressurizing unit of the present invention is not limited to this. The liquid 2 can be any liquid that can transmit pressure, and examples of such liquids include petroleum-based hydraulic oil, fire-resistant hydraulic oil, and other hydraulic oils. The liquid 2 acts on the laminated battery stack 30 as a pressure medium.

[0030] The laminated battery stack 30 is constructed by stacking laminated batteries 3. The laminated battery stack 30 is housed in a sealed state inside a pressurized container 1 and is immersed in a liquid 2 and pressurized. The laminated battery 3 is a battery that has an electrode stack (not shown) consisting of a positive electrode layer, a solid electrolyte layer, and a negative electrode layer, and is sealed in a laminate film. The laminated battery 3 has a current collecting tab 31 and a contact surface 32. The pair of current collecting tabs 31 extend from both ends of the laminated battery 3 in the Y direction. The contact surface 32 is a surface that is perpendicular to the L direction and comes into contact with the holder 4.

[0031] The retaining materials 4 are surface materials that are arranged at intervals in the sealed internal space of the pressurized container 1 and are immersed in the liquid 2 to be pressurized. As shown in Fig. 1, the retaining materials 4 are arranged between the stacked laminated batteries 3 and between the outermost laminated battery 3 and the inner wall of the pressurized container 1, and they maintain the stacked state of the laminated battery stack 30 and can prevent the laminated batteries 3 from shifting and moving in a direction perpendicular to the L direction.

[0032] FIG. 2 is a partially enlarged schematic diagram showing the battery module 10 according to the first embodiment as viewed from the X direction. As shown in FIG. 2, the holding material 4 has a substrate portion 41, a space portion 42, and a contact surface 43. The substrate portion 41 is the main body portion that constitutes the holding material 4 and is formed by accumulating cylindrical shapes. In other words, the holding material 4 is a porous body with partition walls having a circular cross-sectional shape. The multiple cylindrical shapes do not need to be the same size; the holding material 4 may be formed of cylindrical shapes of multiple sizes to match the laminated battery 3. This configuration allows the holding material 4 to have elasticity.

[0033] The holding force exerted by the holding material 4 in the stacking direction of the laminated battery stack 30 is 0.2 MPa or more and 0.5 MPa or less. The holding force can be determined by measuring the stress-strain of the holding material 4. It can also be derived from the relationship between the holding force value y indicated by a pressure measurement element placed between the stacks and the compressibility value x of the holding material 4. In this case, a tactile sensor or pressure-sensitive paper can be used as the pressure measurement element. The compressibility can be determined by dividing the thickness of the holding material 4 placed between the stacks by the thickness of the holding material 4 before being placed between the stacks. This configuration allows the holding material 4 to securely hold the laminated battery 3.

[0034] The substrate 41 is made of polymer resin or metal, and has a compressibility of 5% or less when a pressure of 1 MPa is applied. The compressibility can be determined by measuring the stress-strain of the substrate 41. This prevents the substrate 41 from deforming when pressure from the liquid 2 is applied, and allows the shape of the holding material 4 to be reliably maintained.

[0035] The space 42 is a through-hole formed in the cylindrical shape of the substrate 41, and the holding material 4 has continuous pores. The space 42 is impregnated with the liquid 2, and the porosity of the holding material 4 is 20% or more and 50% or less. The porosity can be calculated from the weight per volume of the holding material 4 and the density of the substrate 41. With this configuration, the holding material 4 has sufficient elasticity and can flexibly deform in response to the expansion and contraction of the laminate-type battery 3.

[0036] Due to the effects of the substrate portion 41 and the space portion 42 described above, the retaining material 4 is configured to have a compressibility of 20% to 50% inclusive when a pressure of 1 MPa is applied. This configuration makes it possible to configure a retaining material 4 that does not deform when pressure is applied from the liquid 2, but that can flexibly deform in response to the expansion of the laminate-type battery 3.

[0037] The contact surface 43 is the surface where the retaining material 4 comes into contact with the laminated battery 3, and is a surface perpendicular to the L direction. As shown in Figures 1 and 2, the edge formed by the contact surface 32 of the laminated battery 3 is covered by the contact surface 43 of the retaining material 4, and the area of ​​the contact surface 43 of the retaining material 4 is larger than that of the contact surface 32 of the laminated battery 3. In other words, the retaining material 4 is arranged so as to cover the edge of the laminated battery 3. With this configuration, the edge of the laminated battery 3 is securely held by the retaining material 4, preventing the laminated battery 3 from shifting in a direction perpendicular to the L direction.

[0038] 2, multiple hollow spaces H1 are formed between the contact surface 32 of the laminated battery 3 and the substrate 41. With this configuration, the liquid 2 filled in the pressurized container 1 contacts the contact surface 32 of the laminated battery 3 through the hollow spaces H1, so that the contact surface 32 of the laminated battery 3 can be uniformly pressurized by the liquid 2 from the L direction.

[0039] FIG. 3 is a partially enlarged schematic diagram viewed from the X direction, showing the state of expansion of the laminated batteries 3 of the battery module 10. The thickness of the laminated batteries 3 changes depending on the charging rate, so repeated charging causes the thickness of the laminated batteries 3 to expand in the L direction, as shown in FIG. 3. Even when the laminated batteries 3 expand, the holding material 4 can flexibly compress in the L direction to follow the expansion of the laminated batteries 3. Conversely, when the laminated batteries 3 contract due to discharge, the holding material 4 can expand in the L direction to follow the laminated batteries 3.

[0040] With this configuration, even if the laminated batteries 3 expand and contract, the retaining material 4 follows the laminated batteries 3 and can maintain the spaces 42. As a result, the liquid 2 impregnated in the spaces 42 maintains a uniform pressurized state of the laminated battery stack 30.

[0041] Furthermore, due to the flexible deformation of the holding material 4, the laminated battery 3 is prevented from shifting in the direction opposite to the L direction, and the current collecting tab 31 is held without changing its position inside the pressurized container 1. This makes it possible to maintain uniformity in the reaction of the solid-state battery module 10 not only at the beginning of life (BOL) but also at the end of life (EOL), and also improve the durability of the solid-state battery module 10.

[0042] According to this embodiment, the following effects are achieved.

[0043] A solid-state battery module 10 according to this embodiment includes a pressurized container 1 filled with a liquid 2, a laminated battery stack 30, and a retaining material 4, and the laminated battery stack 30 is pressurized while immersed in the liquid 2. The retaining material 4 is a cylindrical, elastic porous structure, and is disposed between the laminated batteries 3 and between the laminated batteries 3 and the inner wall of the pressurized container 1.

[0044] With this configuration, the edges of the laminated battery 3 are securely held by the retaining material 4, preventing the laminated battery 3 from shifting in a direction perpendicular to the L direction. Furthermore, because the retaining material 4 is flexibly deformable in response to the expansion and contraction of the laminated battery 3, it is possible to prevent the laminated battery 3 from shifting in a direction opposite to the L direction. This allows the laminated battery 3 to be held while applying uniform pressure to the laminated battery 3 from BOL to EOL, and also allows the position of the current collecting tab 31 to be maintained inside the pressurized container 1.

[0045] Furthermore, by using the retaining material 4 in the solid battery module 10 according to this embodiment, uniform pressure from the liquid 2 can be achieved across the entire surface of the laminated battery 3, and even if the laminated battery 3 expands, uniform pressure can be maintained on the laminated battery stack 30 without applying load to the laminated battery 3, the retaining material 4, or the pressurized container 1.

[0046] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the present invention.

[0047] For example, the laminated battery 3 is not limited to an all-solid-state battery, but may be a battery using a liquid electrolyte. Furthermore, the battery used in the present invention is not limited to a laminated battery, but may be a battery in which an electrode laminate is sealed in a molded body container.

[0048] Furthermore, any material can be used for the retaining material 4 of the present invention as long as it has a porous structure that satisfies the compressibility required for pressure application. For example, a porous sponge may be used for the retaining material 4. Furthermore, although the retaining material 4 of this embodiment has an open pore structure, it may also have a closed pore structure as long as it has sufficient elasticity to accommodate the expansion and contraction of the laminated battery 3.

[0049] [Second embodiment] Next, a second embodiment of the present disclosure will be described in detail with reference to the drawings. The second embodiment differs from the first embodiment in the shape of the holding material 4B. The other configurations are the same as those of the first embodiment, so a description thereof will be omitted. The solid battery module 10B includes a pressurized container 1, a liquid 2, a laminated battery stack 30, and a holding material 4B.

[0050] FIG. 4 is a partially enlarged schematic diagram showing the battery module 10B according to the first embodiment as viewed from the X direction. As shown in FIG. 4, the holding material 4B has a base portion 41B, a space portion 42B, and a contact surface 43B. The base portion 41B is the main body that constitutes the holding material 4B and is formed by an accumulation of corrugated shapes. That is, the holding material 4B is a porous body whose partition walls have a corrugated cross-sectional shape. The repetition interval and height of the corrugations can be changed as appropriate to suit the laminated battery 3. For example, the holding material 4B may be formed by an accumulation of corrugated shapes of different heights.

[0051] The substrate 41B is made of polymer resin or metal, and has a compressibility of 5% or less when a pressure of 1 MPa is applied. The method for measuring the compressibility and porosity is the same as in the first embodiment, and therefore a description thereof will be omitted. This prevents the substrate 41 from deforming when pressure is applied from the liquid 2, and allows the shape of the retention material 4 to be reliably maintained.

[0052] Spaces 42B are through-holes formed by laminating the corrugated shapes of base material 41B, and holding material 4B has continuous pores. With this configuration, spaces 42B are impregnated with liquid 2, and the porosity of holding material 4B is 20% or more and 50% or less. Spaces 42B give holding material 4B elasticity, allowing it to flexibly deform in accordance with the expansion of laminate-type battery 3.

[0053] Due to the effects of the substrate portion 41B and the space portion 42B described above, the holding material 4B is configured to have a compressibility of 20% to 50% inclusive when a pressure of 1 MPa is applied. This configuration makes it possible to configure a holding material 4 that does not deform when pressure is applied from the liquid 2, but can flexibly deform in response to the expansion of the laminate-type battery 3.

[0054] The contact surface 43B is the surface where the retaining material 4B comes into contact with the laminated battery 3, and is a surface perpendicular to the L direction. As shown in Figure 4, the edge portion formed by the contact surface 32 of the laminated battery 3 is covered by the contact surface 43B of the retaining material 4B, and the area of ​​the contact surface 43B of the retaining material 4B is larger than that of the contact surface 32 of the laminated battery 3. With this configuration, the edge portion of the laminated battery 3 is securely held by the retaining material 4B, preventing the laminated battery 3 from shifting in a direction perpendicular to the L direction.

[0055] 4, multiple hollow spaces H2 are formed between the contact surface 32 of the laminated battery 3 and the substrate 41B. With this configuration, the liquid 2 filled in the pressurized container 1 contacts the contact surface 32 of the laminated battery 3 through the hollow spaces H2, so that the contact surface 32 of the laminated battery 3 can be uniformly pressurized by the liquid 2 from the L direction.

[0056] Even when the laminated batteries 3 expand and contract, the wave-shaped shape of the retaining material 4B is compressed as the retaining material 4B deforms, allowing the retaining material 4B to flexibly compress or expand in the L direction, following the laminated batteries 3. This allows the retaining material 4B to retain the spaces 42B even if the thickness of the laminated batteries 3 changes, and the liquid 2 impregnated in the spaces 42B maintains a uniform pressurized state of the laminated battery stack 30.

[0057] The effects achieved by the second embodiment are the same as those of the first embodiment, and therefore a description thereof will be omitted.

[0058] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments and can be modified as appropriate within the scope of the present invention.

[0059] As in the first embodiment, the laminated battery 3 is not limited to an all-solid-state battery, but may be a battery using a liquid electrolyte. Furthermore, the battery used in the present invention is not limited to a laminated battery, but may be a battery in which an electrode laminate is sealed in a molded body container.

[0060] Furthermore, although the holder 4B in this embodiment has an open pore structure, it may have a closed pore structure as long as it has sufficient elasticity to withstand the expansion and contraction of the laminated battery 3. [Explanation of symbols]

[0061] 1 pressurized container, 2 liquid (pressure medium), 3 laminated battery (battery cell), 4, 4B holding material, 10, 10B battery module, 30 laminated battery stack (cell stack), 42, 42B space (pore)

Claims

1. a pressurized vessel filled with a pressure medium; a cell stack housed in the pressurized container and including a plurality of stacked battery cells; the cell stack has holding materials disposed between the stacked battery cells and between the outermost battery cell and the inner wall of the pressure vessel, the holding materials maintaining the stacked state of the cell stack; The battery module, wherein the holding material is made of an elastic porous body.

2. 2. The battery module according to claim 1, wherein the holding material is made of a porous body having interconnected pores, and the interconnected pores are filled with the pressure medium.

3. The battery module according to claim 1 , wherein the porosity of the holding material is 20% or more and 50% or less.

4. The battery module according to claim 1 , wherein the holding material has a compressibility of 20% or more and 50% or less.

5. The battery module according to claim 1 , wherein the holding material has a holding force of 0.2 MPa or more and 0.5 MPa or less.

6. The battery module according to claim 1 , wherein the holding material is disposed so as to cover an edge portion of the battery cell.

7. The battery module according to claim 1 , wherein the holding material is a porous body having partition walls with a circular cross section.

8. The battery module according to claim 1 , wherein the holding material is a porous body having partition walls with a corrugated cross section.

9. The battery module according to any one of claims 1 to 7, wherein the battery cells are all-solid-state battery cells.

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