Battery module

Abstract

To provide a battery module that improves reliability without reducing energy density. Provision. [Solution] The device comprises a laminate in which multiple battery cells are stacked, a pair of first members positioned on either end of the laminate in the direction of the stacking axis, and a pair of end plates positioned on either end of the laminate via the first members, wherein the first members are single-layer members including an elastic material and consist of a battery module positioned in contact with the battery cells and end plates.

Description

Technical Field

[0001] The present disclosure relates to a battery module.

Background Art

[0002] In a battery module including a plurality of battery cells, in order to reduce heat conduction between the battery cells, a heat-insulating inter-cell member is disposed between the battery cells, between the battery cell and a housing or the like, or between the battery cells and between the battery cell and a housing or the like.

[0003] There is known a power supply device capable of suppressing a decrease in heat insulation characteristics of a separator and equalizing the pressure on the pressing surface of a battery cell by disposing a separator having a specific layer structure between the battery cells (Patent Document 1). Further, there is known a battery having excellent flame spread prevention performance by providing a flame spread prevention sheet including a rubber sheet, a heat insulation sheet, and an adhesive layer between the battery cells and between the battery cell and the housing (Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Depending on the use of the battery module or the like, it may be required to more highly suppress the occurrence of defects in the battery module and further improve the reliability. In that case, from the viewpoint of energy density, it is also required not to increase the volume of the entire battery module.

[0006] One embodiment of this disclosure aims to solve the problem of providing a battery module that improves reliability without reducing energy density. [Means for solving the problem]

[0007] The means for solving the problem include the following: <1> A battery module comprising a laminate in which multiple battery cells are stacked, a pair of first members positioned at each end of the laminate in the direction of the stacking axis, sandwiching the laminate, and a pair of end plates positioned at each end of the laminate in the direction of the stacking axis, sandwiching the laminate via the first members, wherein the first members are single-layer members including an elastic material, and are positioned in contact with the battery cells and end plates. <2> Each of the multiple battery cells is provided with a second member, and the second member is a multi-layer member that includes at least an elastic layer containing an elastic body and an insulating layer containing an insulating material. <1> The battery module described above. <3> The first member contains a material common to the elastic layer included in the second member. <2> The battery module described above. <4> The end plate has a multi-layer structure stacked in the direction of the stacking axis, and includes at least a metal layer and a resin layer, the resin layer being stacked so as to cover the entire surface of the metal layer facing the stack. <1> ~ <3> The battery module listed in one of the following. <5> The resin layer has a thickness of 1 mm or more in the direction of lamination axis. <4> The battery module described above. <6> The pair of end plates secure the pair of first members and the laminate under pressure. <1> ~ <5> The battery module listed in one of the following. <7> The battery cell is a solid-state battery cell. <1> ~ <6> The battery module listed in one of the following. [Effects of the Invention]

[0008] According to one embodiment of this disclosure, a battery module can be provided that improves reliability without reducing energy density. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic side view of a battery module, which is one embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic side view of a battery module in which the end plate has a multi-layer structure, which is one embodiment of the present disclosure. [Figure 3] Figure 3 is a schematic diagram of a side view of an example of a conventional battery module. [Modes for carrying out the invention]

[0010] In this disclosure, a numerical range indicated using "~" means a range that includes the numbers written before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in stages in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. In the numerical ranges described in this disclosure, the upper or lower limit stated in one numerical range may be replaced with the values ​​shown in the examples. In this disclosure, a combination of two or more preferred embodiments is a more preferred embodiment. When embodiments are described in this disclosure with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto. In addition, to avoid making the figures cluttered, multiple components that are substantially the same may only be partially labeled with reference numerals.

[0011] <Battery Module> A battery module according to one embodiment of the present disclosure comprises a laminate in which a plurality of battery cells are stacked, a pair of first members, and a pair of end plates. The pair of first members are positioned at each end of the laminate in the direction of the stacking axis, sandwiching the laminate. The end plates are positioned at each end of the laminate in the direction of the stacking axis, sandwiching the laminate via the first members. The first members are single-layer members containing an elastic material, and are positioned in contact with the battery cells and the end plates. That is, one of the pair of end plates is positioned in contact with the first member at one end of the laminate in the direction of the stacking axis, and the other is positioned in contact with the first member at the other end of the laminate in the direction of the stacking axis.

[0012] As shown in Figure 3, in a conventional battery module 100, inter-cell members 130 are placed, for example, between battery cells 110 and between battery cells 110 and end plates 120. The inter-cell members 130 are made of a laminate formed by stacking an elastic member 140 and a heat insulating member 150. The elastic member 140 and heat insulating member 150 of the inter-cell members 130 help to accommodate the expansion and contraction of the battery cells 110 and suppress heat conduction between the battery cells 110.

[0013] The inventors investigated how to improve the reliability of a battery module without reducing its energy density, and focused on the internal configuration of the battery module. They found that by placing a specific member with a different layer configuration from the inter-cell members between the battery cells and the end plate, it is possible to improve energy density and achieve a higher level of reliability.

[0014] Although the detailed mechanism by which the above effects are obtained is unknown, it is presumed that in a battery module, by arranging a specific member containing an elastic body with a different layer configuration from the inter-cell members at the axial end of the stacked battery cells, the following occurs.

[0015] First, the battery cells adjacent to the end plates are considered to have a higher non-uniformity of the stacking axial forces applied to both main surfaces of the battery cells when the battery cells expand in volume because the surrounding layer configurations of the battery cells adjacent to each other are different. However, by arranging specific members at the stacking axial ends of the end plates and the battery cells, it is presumed that the non-uniformity of the stacking axial forces is eliminated in order to preferably mitigate the influence of the volume expansion of the battery cells adjacent to the end plates. As a result, it is presumed that the inclination, displacement, etc. of each component of the laminate are suppressed, and the displacement, etc. of peripheral components such as bridges for electrode connection are also suppressed, improving the reliability as a battery module. Also, it is presumed that, compared with the case where no member is arranged between the end plate and the battery cell adjacent to this end plate, for example, excessive force applied to the end plate is suppressed, improving the reliability as a battery module.

[0016] Second, in a battery module, since it is possible to arrange a specific member including an elastic body having a layer configuration different from that of the inter-cell member as a single-layer configuration with a thickness thinner than that of the inter-cell member at the stacking axial ends of the battery cells, it is presumed that the volume of the entire battery module decreases and the energy density is improved.

[0017] Hereinafter, a battery module according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2.

[0018] As shown in FIG. 1, a battery module 10 according to an embodiment of the present disclosure includes a laminate 12 in which a plurality of battery cells 11 are stacked, a pair of first members 13, and a pair of end plates 14.

[0019] (Laminate) The laminate 12 is made up of multiple battery cells 11 stacked together. Each battery cell 11 has a required thickness, and its thickness direction, when viewed in the stacking axis direction (X direction in Figure 1), is approximately rectangular. Multiple battery cells 11 are arranged in the stacking axis direction X to form the laminate 12. In the battery module 10, multiple battery cells 11 are connected in series or in parallel in the laminate 12, and the electrodes 15 enable the output of DC power at the required voltage.

[0020] The laminate 12 is formed by stacking, for example, five battery cells 11a to 11e. The number of battery cells 11 is not limited to five; it can be two or more, depending on the application of the battery module 10, for example, 20 to 30 cells.

[0021] The battery cell 11 is a secondary battery such as a lithium-ion battery. However, the battery cell 11 is not limited to lithium-ion batteries; various secondary batteries such as semi-solid batteries having a gel layer containing electrolyte and polymer between the electrode and the solid electrolyte, all-solid batteries using a solid electrolyte, lead-acid batteries, nickel-cadmium batteries, and nickel-metal hydride batteries may be used. The solid electrolyte may contain less than 10% by mass of electrolyte relative to the total amount of electrolyte. Furthermore, the battery cell 11 is not limited to secondary batteries; primary batteries such as manganese dry cells, lithium graphite fluoride primary batteries, and lithium manganese dioxide primary batteries may be used. Among these, semi-solid batteries or all-solid batteries are preferred, and all-solid batteries are more preferred.

[0022] (First component) The pair of first members 13 are positioned at both ends of the laminate 12 in the lamination axis direction X, flanking the laminate 12. First member 13a is positioned at one end of the laminate 12 in the lamination axis direction X, and first member 13b is positioned at the other end in the lamination axis direction X. First member 13a and first member 13b constitute a pair of first members 13. In this disclosure, first member 13a and first member 13b may not be distinguished and may be referred to as first member 13.

[0023] The first member 13 is a single-layer member containing an elastic body. The first member 13 is a single member made entirely of the same material. Because the first member 13 is a single member with elasticity throughout, it is possible to impart appropriate elasticity with high uniformity to the entire first member 13. Therefore, it is possible to more reliably receive and uniformize the expansion pressure of the battery cell 11 adjacent to the end plate 14. The shape of the first member 13 is similar to that of the battery cell 11, with a substantially rectangular shape in the stacking axis direction (X direction in Figure 1), which is the thickness direction. From the viewpoint of avoiding interference with surrounding parts, it is preferable that the height and width of the first member 13 in the stacking axis direction are less than or equal to those of the battery cell 11.

[0024] As the first member 13, an elastic material conventionally used for the inter-cell members of the battery module 10 can be used. The first member 13 is preferably set according to the type of battery cell 11, the degree of expansion, size, etc.

[0025] The first member 13 can be made thinner in the stacking axis direction X depending on the expansion pressure of the battery cell 11, the type of elastic body, etc. Therefore, compared to the case where a multi-layer structure member consisting of an elastic body layer and a heat insulating material layer is used as the first member 13 in contact with the end plate 14, the thickness can be made thinner because it consists only of a layer containing an elastic body, and the energy density of the battery module 10 can be further improved. This is because, normally, the elastic performance of layers other than the elastic body layer, such as heat insulating material layers, is inferior to the elastic performance of the elastic body layer, so by making the first member 13 consist only of a layer containing an elastic body, the elastic performance of the first member 13 can be made more favorable.

[0026] The elastic body in the first member 13 refers to a material with a Young's modulus of 200 kPa or more, and can be any material such as rubber that has elasticity, a porous or sponge-like structure that has elasticity, or a material that is elastic itself and has a porous or sponge-like structure. Furthermore, since the elastic body prevents the spread of fire, it is preferable that it is a material with excellent flame retardancy that does not disappear even at high temperatures and can maintain insulation from surrounding parts.

[0027] Specifically, the elastic material is preferably a Si-based rubber material, and more preferably silicone rubber. Furthermore, from the viewpoint of imparting appropriate elasticity, it is even more preferable to use foamed silicone rubber.

[0028] (End plate) The battery module 10 includes a pair of end plates 14 positioned at both ends of the stacking axis X, sandwiching the stacked body 12 via a first member 13. At one end of the stacking axis X of the stacked body 12, a first member 13a is positioned, and an end plate 14a is positioned adjacent to the first member 13a. At the other end of the stacking axis X, a first member 13b is positioned, and an end plate 14b is positioned adjacent to the first member 13b. The end plates 14a and 14b constitute a pair of end plates 14. In this disclosure, the end plates 14a and 14b may not be distinguished and may simply be referred to as the end plate 14.

[0029] The end plate 14 functions as a restraining plate that fixes the first member 13 and the laminate 12 in a pressurized state. Furthermore, since the end plate 14 does not deform under the expansion pressure of the laminate 12, it is preferable that it be a metal plate made of metal. As for the metal, conventionally known metals can be used for the end plate 14. Examples of metals include aluminum and iron, and although it depends on the type of battery module 10, aluminum or iron is preferred from the viewpoint of the function of the end plate 14 and weight reduction.

[0030] The end plate 14 preferably applies a restraining pressure of, for example, 0.1 MPa or more, 1 MPa or more, or 5 MPa or more in the stacking axis direction X of the stacked body 12, depending on the type of battery cell 11, etc. Alternatively, it is preferable to apply a restraining pressure of, for example, 100 MPa or less, 50 MPa or less, or 20 MPa or less.

[0031] The end plate 14 has a substantially rectangular shape when viewed in the stacking axis direction (X direction in Figure 1), which is the thickness direction, and is preferably about the same size as the battery cell 11 from the viewpoint of its function as a restraining plate.

[0032] (Battery module configuration) In the battery module 10, the end plate 14, the first member 13, and the battery cell 11 are arranged in contact with each other in this order at both ends in the stacking axis direction X. Specifically, at one end in the stacking axis direction X, the end plate 14a, the first member 13a, and the battery cell 11a are arranged in contact with each other in this order. At the other end in the stacking axis direction X, the end plate 14b, the first member 13b, and the battery cell 11e are arranged in contact with each other in this order.

[0033] In the battery cell 11a or battery cell 11e adjacent to the end plate 14, the first member 13 effectively mitigates and equalizes the effects of volume expansion, thereby eliminating non-uniformity of force in the stacking axis direction X. This suppresses tilting, displacement, etc., of each component, as well as displacement of peripheral components such as electrode connection bridges, thereby improving the reliability of the battery module 10. Furthermore, the first member 13 allows for a thinner thickness and excels at equalizing the expansion pressure of the battery cell 11. Therefore, the battery module 10 is a battery module that improves reliability without reducing energy density.

[0034] The battery module 10 may also include a plurality of second members 16, each positioned between a plurality of battery cells 11. Preferably, the second members 16 are multi-layer members stacked in the stacking axis direction X. Preferably, the second member 16 includes at least an elastic layer 17 containing an elastic body and a thermal insulation layer 18 containing a thermal insulation material. The second members 16 can suppress thermal runaway caused by adjacent battery cells 11 and effectively restrain the battery cells 11. Therefore, by arranging a first member 13 that performs an appropriate function at the end of the stacking axis direction X of the battery module 10, and arranging a second member 16 that performs an appropriate function between the battery cells 11, the battery module 10 can be made into a battery module that does not reduce energy density and improves reliability.

[0035] The second member 16 may be any multi-layer member stacked in the stacking axis direction X, and may be a two-layer structure or a three-layer structure. For example, it may be a three-layer structure in which an insulating layer 18, an elastic layer 17, and another insulating layer 18 are stacked in that order. It may also include layers other than the elastic layer 17 and the insulating layer 18.

[0036] The elastic layer 17 or the thermal insulation layer 18 can be made from materials conventionally known for use as inter-cell components. The elastic body included in the elastic layer 17 can be the same as that described for the elastic body in the first component 13. The thermal insulation material included in the thermal insulation layer 18 refers to a thermal insulation material with a thermal conductivity of 0.03 W / (m·K) or less, and silica aerogel with silica as the main material is preferred, and from the viewpoint of thermal insulation performance, silica aerogel composed of a silicon dioxide skeleton and 90% to 98% air is more preferred. The elastic layer 17 or the thermal insulation layer 18 is preferably made of a material with excellent flame retardancy that can maintain insulation from surrounding components.

[0037] Regarding the shape of the elastic layer 17 or the heat insulating layer 18, from the viewpoint of avoiding interference with surrounding parts, it is preferable that the height and width in the axial view of the laminate are less than or equal to the battery cell 11. Furthermore, it is preferable that the thickness of the elastic layer 17, the heat insulating layer 18, and the second member 16 be as thin as possible.

[0038] Preferably, the first member 13 contains a material common to the elastic layer 17 included in the second member 16. Preferably, the first member 13 and the elastic layer 17 included in the second member 16 are formed from the same material. For example, if a sheet-like material is used as the material for the first member 13 and the elastic layer 17, they may be cut from the same material to form the first member 13 and the elastic layer 17. Therefore, the first member 13 and the elastic layer 17 have substantially the same composition and thickness. This makes it possible to reduce the manufacturing cost of the battery module 10. In addition, compared to using a laminate similar to the second member 16 as the first member 13, a single-layer structure first member 13 can be used, which makes it possible to reduce the thickness and improve the energy density of the battery module 10.

[0039] The end plate 14 may have a multi-layer structure stacked in the stacking axis direction X. If the end plate 14 has a multi-layer structure, it is preferable that it includes at least a metal layer and a resin layer. Furthermore, from the viewpoint of insulation, it is preferable that the resin layer is stacked so as to cover the entire surface of the metal layer on the side facing the laminate 12.

[0040] The metal in the metal layer is the same as described above for the end plate 14. The resin in the resin layer is preferably a resin that does not generate heat and has insulating properties. Specifically, examples of thermoplastic resins include polyethylene, polypropylene, and polycarbonate, and examples of thermosetting resins include silicone resin. From the viewpoint of processability and cost, polypropylene (hereinafter referred to as PP) is preferred as the resin. From the viewpoint of insulating properties, examples of preferred types of PP include homopolymer PP, random copolymer PP, unfilled grade PP, highly crystalline PP, electrical insulating grade PP, and PP blended with additives such as flame retardant additives.

[0041] The resin layer is preferably laminated as an insulating layer to cover the entire surface of the metal layer on the laminate side, in order to prevent discharge to the end plate 14 by the battery cells 11 that are close to the end plate 14. Specifically, it is preferable to form the resin layer to a size that can cover at least the front surface of the metal layer without making it smaller than the size of the metal layer. Furthermore, the thickness of the resin layer is preferably such that it can exhibit insulating properties from the viewpoint of insulating function, and is not too thick from the viewpoint of energy density. Specifically, the thickness of the resin layer in the lamination axis direction X is preferably 1 mm or more. From the viewpoint of energy density, a thinner resin layer is preferable.

[0042] As shown in Figure 2, the end plate 14 has a multi-layer structure, and it is preferable that the metal layer 21 and the resin layer 22 are laminated in this order in the lamination axis direction X. The resin layer 22 is sized to cover the metal layer 21 and is preferably in contact with the first member 13.

[0043] <Types of battery modules> One embodiment of the battery module 10 of this disclosure is suitable when the battery cell 11 includes a battery cell 11 whose volume changes due to charging and discharging. The battery cell 11 is preferably a solid-state battery, a lithium-ion battery, etc. When the battery cell 11 is a solid-state battery, etc., which is prone to volume changes due to expansion and contraction, the battery module 10 can exhibit its effects more significantly. The solid-state battery may be a semi-solid-state battery or a fully solid-state battery.

[0044] <Applications of battery modules> The applications of the battery module 10, which is one embodiment of the present disclosure, are not particularly limited. Typical applications include power supplies for vehicles, electronic devices, and electrical storage systems. It can be a high-capacity battery module containing multiple battery cells 11. Therefore, among these, the battery of the present disclosure is preferably used as a power supply for vehicles. Examples of vehicles include electric four-wheeled vehicles, electric two-wheeled vehicles, gasoline vehicles, diesel vehicles, etc. Examples of electric four-wheeled vehicles include electric vehicles (BEV: Battery Electric Vehicle) and plug-in hybrids. Examples include cars (PHEV: Plug-in Hybrid Electric Vehicle) and hybrid cars (HEV: Hybrid Electric Vehicle). Examples of electric two-wheeled vehicles include electric motorcycles and electric-assist bicycles. [Explanation of Symbols]

[0045] 10 Battery Modules 11, 11a, 11b, 11c, 11d, 11e battery cells 12-layer structure 13, 13a, 13b First member 14, 14a, 14b End Plates 15 electrodes 16. Second Member 17 Elastic layer 18. Insulation layer 21 Metal layer 22 Resin layer X stacking axis

Claims

1. A laminate in which multiple battery cells are stacked, A pair of first members are arranged at each end of the laminate in the direction of the lamination axis, sandwiching the laminate. A pair of end plates are arranged at each end in the lamination axis direction, sandwiching the laminate via the first member, Equipped with, The first member is a single-layer member containing an elastic body, and is arranged in contact with the battery cell and the end plate in a battery module.

2. Each of the multiple battery cells is provided with a second member, The battery module according to claim 1, wherein the second member is a multi-layer member comprising at least an elastic layer containing an elastic body and an insulating layer containing an insulating material.

3. The battery module according to claim 2, wherein the first member includes a material common to the elastic layer included in the second member.

4. The end plate has a multi-layer structure stacked in the direction of the stacking axis, and includes at least a metal layer and a resin layer. The battery module according to claim 1, wherein the resin layer is laminated to cover the entire surface of the metal layer on the laminate side.

5. The battery module according to claim 4, wherein the resin layer has a thickness of 1 mm or more in the lamination axis direction.

6. The battery module according to claim 1, wherein a pair of end plates fix the pair of first members and the laminate in a pressurized state.

7. The battery module according to claim 1, wherein the battery cell is a solid-state battery cell.

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