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 Art

[0002] Conventionally, a battery module that stacks a plurality of laminated batteries enclosed in a laminate film and applies pressure restraint from the upper and lower surfaces in the stacking direction to reduce the resistance distribution in the electrodes and make the reaction uniform is widely known. However, in the pressure restraint method of uniaxially restraining from the upper and lower surfaces, the uniformity of the reaction is insufficient, so not only good initial characteristics and the durability of the battery module cannot be obtained, but also there is a problem that the yield decreases. In order to solve these problems, it is necessary to improve the pressure restraint force of the battery module, and the exterior for restraint tends to become bulky.

[0003] On the other hand, a liquid immersion pressure vessel that does not use such an exterior for restraint has been proposed (see Patent Document 1). The pressure oil and the pouch cell (laminated battery) of Patent Document 1 are stored in a sealed pressure vessel, and the pouch cell is surrounded by the pressure oil to maintain the pressurized state, and the restraint pressure is applied not only uniaxially on the upper and lower surfaces but also from all directions. Further, a plurality of pouch cells can be stacked to form an array group.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when multiple pouch cells are stacked, the thickness of the battery changes depending on the charge level, which causes a problem of misalignment between the pouch cells. Therefore, a method is known in which a retaining material is placed between the pouch cells to hold them in place and prevent them from moving. Thus, when a solid battery module with stacked pouch cells is stored in a liquid-immersion pressurized container as described in Patent Document 1, the configuration of these retaining materials becomes a challenge.

[0006] For example, if a soft retaining material is used, the retaining material itself can be crushed by the internal pressure of the container, creating a gap between the laminated battery (pouch cell) and the retaining material, which can cause the laminated batteries to shift out of place. Conversely, if a hard retaining material is used, the retaining material adheres tightly to the surface of the laminated battery, preventing the pressurized oil, which acts as the pressure medium, from contacting the laminated battery. As a result, the laminated battery is not pressurized by the pressure medium. Furthermore, because hard retaining materials cannot be deformed, when the battery expands during charging, it can put stress on the laminated battery, the retaining material, and the pressurized container.

[0007] The present invention aims to provide a battery module in which the entire surface of the battery cell is uniformly pressurized and is not subjected to stress due to expansion during charging. [Means for solving the problem]

[0008] (1) The battery module of the present invention (for example, the battery modules 10, 10B described later) comprises a pressurized container (for example, the pressurized container 1 described later) filled with a pressure medium (for example, the liquid 2 described later), and a cell stack (for example, the laminated battery stack 30 described later) housed in the pressurized container and having a plurality of battery cells (for example, the laminated battery 3 described later) stacked on top of each other. The cell stack has a retaining material (for example, the retaining material 4 described later) positioned 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 material is made of an elastic porous material.

[0009] By housing the cell stack in a pressurized container filled with a pressure medium, the entire surface of the battery cells can be uniformly pressurized. Furthermore, by placing retaining material between the battery cells and between the outermost battery cell and the inner wall of the pressurized container, the movement of the battery cells in the direction opposite to the stacking direction can be suppressed, thereby maintaining the stacked state of the cell stack. In addition, since the retaining material is an elastic porous material, when the thickness of the battery cells changes during charging, the retaining material is compressed and stretched in accordance with the expansion and contraction of the battery cells, so the uniformity of the reaction of the battery module can be maintained without changing the position of the battery cells, and durability can also be improved. Moreover, because the retaining material is elastic, uniform pressurization of the cell stack can be maintained without putting a load on the pressurized container, the cell stack, and the retaining material.

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

[0011] Since the retaining material is a continuous porous body with through holes, the pressure medium is sufficiently impregnated into the interior of the through holes, and uniform pressure can be maintained on the cell laminate in a more favorable state.

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

[0013] The porosity of the retaining material is between 20% and 50%, which gives the retaining material sufficient elasticity and allows it to flexibly deform to follow the expansion and contraction of the battery cell.

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

[0015] The compression ratio of the retaining material is between 20% and 50%, so that it does not deform when pressure is applied to the pressure medium, but can flexibly deform to follow the expansion of the battery cell.

[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 making the holding force of the holding material be not less than 0.2 MPa and not more than 0.5 MPa, it is possible to suppress the battery cell from shifting and moving in the direction opposite to the compression direction, and it is possible to more remarkably maintain the stacked state of the cell laminate.

[0018] (6) The holding material of the present invention is a porous body in which the cross-sectional shape of the partition wall is circular.

[0019] By making the cross-sectional shape of the partition wall constituting the holding material circular, it is possible to form a porous body capable of impregnating the holding material with a sufficient solvent.

[0020] (7) The holding material of the present invention is a porous body in which the cross-sectional shape of the partition wall is wavy.

[0021] By making the cross-sectional shape of the partition wall constituting the holding material wavy, it is possible to form a porous body capable of impregnating the holding material with a sufficient solvent.

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

[0023] In an all-solid-state battery, since it is an important issue to maintain uniform pressurization from the pressure medium, favorable effects can be achieved by using the present invention.

Advantages of the Invention

[0024] According to the present invention, in a battery module having a cell laminate in which battery cells are stacked, the entire surface of the battery cell is uniformly pressurized by a pressure medium filled in a pressure vessel, and there is a holding material capable of maintaining the stacked state of the cell laminate without changing the position of the battery cell. During charging, it is possible to provide a battery module capable of maintaining uniform pressurization of the cell laminate without applying a load to the pressure vessel, the cell laminate, and the holding material.

Brief Description of the Drawings

[0025] [Figure 1]It is a schematic diagram showing a battery module according to the first embodiment. [Figure 2] It is an enlarged schematic diagram showing a battery module according to the first embodiment. [Figure 3] It is an enlarged schematic diagram showing the state in which the laminated battery in FIG. 2 is expanded. [Figure 4] It is an enlarged schematic diagram showing a battery module according to the second embodiment.

Embodiments for Carrying out the Invention

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

[0027] In the drawings of the present invention, three predetermined directions orthogonal to each other are represented by the XYZ orthogonal coordinate system. The "X direction" represents the width direction of the solid battery module 10, the "Y direction" represents the length direction of the solid battery module 10, the "Z direction" represents the height direction of the solid battery module 10, and the "L direction" represents the stacking direction of the laminated battery 3, respectively.

[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 battery module 10 includes a pressure vessel 1, a liquid 2, a laminated battery stack 30, and a holding member 4. The pressure vessel 1 is used with a main body portion and a lid portion (not shown) sealed, and forms a sealed space inside. The pressure vessel 1 may be made of any material as long as it can maintain the pressurized state of the liquid 2. For example, it may be made of a metal such as aluminum or stainless steel, or a resin.

[0029] Liquid 2 is filled into the pressurized container 1 and pressurized by a pressurizing unit (not shown). A pressurizing pump can be used as the pressurizing unit, but the pressurizing unit of the present invention is not limited to this. Liquid 2 can be any liquid capable of transmitting pressure; for example, hydraulic fluids such as petroleum-based hydraulic oil or flame-retardant hydraulic oil can be used. Liquid 2 acts as a pressure medium on the laminated battery stack 30.

[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 the pressurized container 1 and is immersed in liquid 2 and pressurized. The laminated battery 3 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 includes current collector tabs 31 and a contact surface 32. A pair of current collector tabs 31 lead out from both ends of the laminated battery 3 in the Y direction. The contact surface 32 is a surface perpendicular to the L direction and is the surface that contacts the retaining material 4.

[0031] The retaining material 4 is a surface material that is placed in multiple locations at intervals within the sealed internal space of the pressurized container 1 and is immersed in liquid 2 and pressurized. As shown in Figure 1, the retaining material 4 is placed between the stacked laminated batteries 3 and between the outermost laminated battery 3 and the inner wall of the pressurized container 1, thereby maintaining the stacked state of the laminated battery stack 30 and preventing the laminated batteries 3 from shifting in a direction perpendicular to the L direction.

[0032] Figure 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 Figure 2, the retaining material 4 has a base material portion 41, a space portion 42, and a contact surface 43. The base material portion 41 is the main body portion that constitutes the retaining material 4 and is composed of an accumulation of cylindrical shapes. That is, the retaining material 4 is a porous body with a circular cross-sectional shape of the partition wall. The multiple cylindrical shapes are not limited to the same size, and the retaining material 4 may be composed of multiple cylindrical shapes of different sizes to match the laminate-type battery 3. With this configuration, the retaining material 4 can have elasticity.

[0033] The holding force exerted by the holding material 4 in the stacking direction of the laminated battery stack 30 is between 0.2 MPa and 0.5 MPa. The holding force can be determined from the stress-strain measurement of the holding material 4. Alternatively, it can be derived from the relationship between the holding force value y indicated by a pressure measuring 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 measuring element. The compressibility is determined by dividing the thickness of the holding material 4 placed between the stacks by the thickness of the holding material 4 before it was placed between the stacks. With this configuration, the holding material 4 can reliably hold the laminated battery 3.

[0034] The base material 41 is made of polymer resin or metal, and its compressibility under a pressure of 1 MPa is 5% or less. The compressibility can be determined by measuring the stress and strain of the base material 41. As a result, the base material 41 does not deform under pressure from the liquid 2, and the shape of the retaining material 4 can be reliably maintained.

[0035] The space 42 is a cylindrical through-hole formed in the base material 41, and the retaining material 4 has continuous pores. The space 42 is impregnated with liquid 2, and the porosity of the retaining material 4 is between 20% and 50%. The porosity can be determined from the weight per unit volume of the retaining material 4 and the density of the base material 41. With this configuration, the retaining material 4 has sufficient elasticity and can flexibly deform to follow the expansion and contraction of the laminate-type battery 3.

[0036] Due to the effects of the base material portion 41 and the space portion 42 described above, the retaining material 4 is configured to have a compressibility of 20% to 50% when a pressure of 1 MPa is applied. With this configuration, the retaining material 4 does not deform when pressure is applied to the liquid 2, but can be flexibly deformed to follow the expansion of the laminate-type battery 3.

[0037] The contact surface 43 is the surface on which the retaining material 4 contacts the laminated battery 3, and is perpendicular to the L direction. As shown in Figures 1 and 2, the edge portion 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 the contact surface 32 of the laminated battery 3. In other words, the retaining material 4 is positioned to cover the edge portion of the laminated battery 3. With this configuration, the edge portion of the laminated battery 3 is securely held by the retaining material 4, and it is possible to suppress the laminated battery 3 from shifting and moving in a direction perpendicular to the L direction.

[0038] As shown in Figure 2, multiple hollow portions H1 are formed between the contact surface 32 of the laminated battery 3 and the base material portion 41. With this configuration, the liquid 2 filled in the pressurized container 1 is in contact with the contact surface 32 of the laminated battery 3 via the hollow portions 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] Figure 3 is a partially enlarged schematic diagram viewed from the X direction, showing the expansion of the laminated battery 3 in the battery module 10. The laminated battery 3 has the characteristic that its thickness changes depending on the charge level, and as charging is repeated, the thickness of the laminated battery 3 expands in the L direction, as shown in Figure 3. Even when the laminated battery 3 expands, the retaining material 4 can flexibly compress in the L direction to follow the expansion of the laminated battery 3. Conversely, when the laminated battery 3 contracts due to discharge, the retaining material 4 can stretch in the L direction to follow the expansion of the laminated battery 3.

[0040] With this configuration, even if the laminated battery 3 expands and contracts, the retaining material 4 can follow the laminated battery 3 and hold the space 42. As a result, the liquid 2 impregnated in the space 42 maintains a uniform pressurized state of the laminated battery stack 30.

[0041] Furthermore, the flexible deformation of the retaining material 4 prevents the laminated battery 3 from shifting in the direction opposite to the L direction, and the position of the current collecting tab 31 is maintained without change inside the pressurized container 1. As a result, the uniformity of the reaction of the solid battery module 10 can be maintained not only at BOL (Beginning of Life) but also at EOL (End of Life), and the durability of the solid battery module 10 can also be improved.

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

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

[0044] This configuration ensures that 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 can flexibly deform to follow 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. As a result, the laminated battery 3 can be held while uniform pressure is applied to it from BOL to EOL, and the position of the current collecting tab 31 can 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 pressurization from the liquid 2 can be achieved over the entire surface of the laminated battery 3. Even if the laminated battery 3 expands, uniform pressurization to the laminated battery stack 30 can be maintained without putting a load on the laminated battery 3, the retaining material 4, and the pressurizing container 1.

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

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

[0048] Furthermore, the retaining material 4 of the present invention can be made of any material as long as it is a porous structure that satisfies the compressibility under applied pressure. For example, a porous sponge may be used as the retaining material 4. In addition, although the retaining material 4 in this embodiment has a continuous porous structure, it may also have an closed-porous structure as long as it has sufficient elasticity against the expansion and contraction of the laminate-type battery 3.

[0049] [Second Embodiment] Next, a second embodiment of this disclosure will be described in detail with reference to the drawings. The difference between the second embodiment and the first embodiment is the shape of the retaining material 4B. The other components are the same as those of the first embodiment, so their description will be omitted. The solid battery module 10B comprises a pressurized container 1, a liquid 2, a laminated battery stack 30, and a retaining material 4B.

[0050] Figure 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 Figure 4, the retaining material 4B has a base material portion 41B, a space portion 42B, and a contact surface 43B. The base material portion 41B is the main body portion that constitutes the retaining material 4B and is composed of an accumulation of corrugated shapes. That is, the retaining material 4B is a porous body in which the cross-sectional shape of the partition wall is corrugated. The repeating interval and height of the corrugated shape can be appropriately changed to match the laminated battery 3. For example, the retaining material 4B may be composed of an accumulation of corrugated shapes of different heights.

[0051] The base material 41B is made of polymer resin or metal, and its compressibility under a pressure of 1 MPa is 5% or less. The method for measuring the compressibility and porosity is the same as in the first embodiment, so a detailed explanation is omitted. As a result, the base material 41 does not deform under pressure from the liquid 2, and the shape of the retaining material 4 can be reliably maintained.

[0052] The space portion 42B is a through-hole formed by the lamination of the corrugated shape of the base material portion 41B, and the retaining material 4B has continuous pores. With this configuration, the space portion 42B is impregnated with the liquid 2, and the porosity of the retaining material 4B is between 20% and 50%. The space portion 42B gives the retaining material 4B elasticity, allowing it to deform flexibly in accordance with the expansion of the laminate-type battery 3.

[0053] Due to the effects of the base material portion 41B and the space portion 42B described above, the retaining material 4B is configured to have a compressibility of 20% to 50% when a pressure of 1 MPa is applied. With this configuration, the retaining material 4 can be made such that it does not deform when pressure is applied to the liquid 2, but can flexibly deform to follow the expansion of the laminate-type battery 3.

[0054] The contact surface 43B is the surface on which the retaining material 4B contacts the laminated battery 3, and is 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 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, and it is possible to suppress the laminated battery 3 from shifting and moving in a direction perpendicular to the L direction.

[0055] As shown in Figure 4, multiple hollow portions H2 are formed between the contact surface 32 of the laminated battery 3 and the base material portion 41B. With this configuration, the liquid 2 filled in the pressurized container 1 is in contact with the contact surface 32 of the laminated battery 3 via the hollow portions 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 battery 3 expands and contracts, the corrugated shape of the retaining material 4B is compressed as it deforms, allowing the retaining material 4B to follow the laminated battery 3 and be flexibly compressed or stretched in the L direction. As a result, even if the thickness of the laminated battery 3 changes, the retaining material 4B can hold the space 42B, and the liquid 2 impregnated in the space 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, so a detailed explanation will be omitted.

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

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

[0060] Furthermore, although the retaining material 4B in this embodiment has a continuous pore structure, it may also have an closed-pore structure as long as it has sufficient elasticity against the expansion and contraction of the laminate-type 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 (pores)

Claims

1. A pressurized container filled with a pressure medium, The system comprises a cell stack in which a plurality of battery cells are stacked and housed in the aforementioned pressurized container, The cell stack has a retaining material that is placed between the stacked battery cells and between the outermost battery cell and the inner wall of the pressurized container, and that maintains the stacked state of the cell stack. The aforementioned retaining material is made of an elastic porous material and is provided to cover the entire outer surface of the battery cells perpendicular to the stacking direction.

2. The battery module according to claim 1, wherein the retaining material is made of a porous body having continuous pores, and the pressure medium is filled inside the continuous pores.

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

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

5. The battery module according to claim 1, wherein the retaining material is arranged to cover the edges of the battery cells when the battery cells expand in the stacking direction.

6. The battery module according to claim 1, wherein the retaining material is a porous body with a circular cross-sectional shape of the partition wall, and the pressure medium is filled in the space formed by the partition wall.

7. The battery cell has a current-collecting tab extending in one direction perpendicular to the stacking direction, The battery module according to claim 1, wherein the retaining material is a cylindrical body extending in one direction and filled with the pressure medium.

8. The battery module according to claim 1, wherein the retaining material is a porous body whose partition walls have a corrugated cross-sectional shape, and the pressure medium is filled in the space formed by the partition walls.

9. The battery module according to any one of claims 1 to 8, wherein the battery cell is an all-solid-state battery cell.

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