Battery module

Abstract

The present invention provides a battery module capable of suppressing misalignment of elastic members in a direction perpendicular to the stacking direction of battery cells. [Solution] The battery module comprises a battery cell stack in which a plurality of battery cells 11 are stacked, and a first elastic member 14A disposed between the plurality of battery cells 11. The first elastic member 14A comprises a pouch 20 in which gas is sealed and has a first sealing portion 21A and a second sealing portion 21B at both ends in a direction perpendicular to the stacking direction of the battery cells 11, a first support member 22A that supports substantially the entire area of ​​the first sealing portion 21A, and a second support member 22B that supports substantially the entire area of ​​the second sealing portion 21B. The ratio of the thickness of the first support member 22A to the thickness of the pouch 20 and the ratio of the thickness of the second support member 22B to the thickness of the pouch 20 are, each, 0.2 or more and 3.5 or less.

Description

[Technical Field]

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

[0002] In recent years, research and development has been conducted on battery modules that contribute to energy efficiency, in order to ensure that more people have access to affordable, reliable, sustainable, and advanced energy.

[0003] Patent Document 1 describes a module containing a flat-type secondary battery. In this module, a module casing that pressurizes and fixes the flat-type secondary battery is placed between the module casing and the flat-type secondary battery, with a fluid-containing bag that seals and encloses a fluid in between. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-303579 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, when the fluid-containing bags described in Patent Document 1 are placed between multiple battery cells, misalignment of the fluid-containing bags in a direction perpendicular to the stacking direction of the battery cells is likely to occur.

[0006] The present invention aims to provide a battery module that can suppress misalignment of elastic members in a direction perpendicular to the stacking direction of battery cells. [Means for solving the problem]

[0007] (1) A battery module comprising a battery cell stack in which a plurality of battery cells are stacked, and an elastic member disposed between the plurality of battery cells, wherein the elastic member comprises a pouch containing gas and having a first sealing portion and a second sealing portion at both ends in a direction perpendicular to the stacking direction of the battery cells, a first support member supporting at least a portion of the first sealing portion, and a second support member supporting at least a portion of the second sealing portion, wherein the ratio of the thickness of the first support member to the thickness of the pouch and the ratio of the thickness of the second support member to the thickness of the pouch are 0.2 or more and 3.5 or less.

[0008] (2) The battery module according to (1), wherein in a direction perpendicular to the stacking direction of the battery cells, the length of the first support member and the length of the second support member are less than or equal to the length of the pouch.

[0009] (3) The battery module according to (1) or (2), wherein the seal strength of the first sealing portion and the seal strength of the second sealing portion are 1 N / mm or more.

[0010] (4) The battery module according to any one of (1) to (3), wherein the first elastic member has a portion of the first sealing portion and a portion of the second sealing portion facing the battery cell.

[0011] (5) The battery module according to any one of (1) to (4), wherein the pouch has a third sealing portion that extends in a direction perpendicular to the stacking direction of the battery cells, and the third sealing portion faces the battery cells.

[0012] (6) The battery module according to (5), wherein the third sealing portion includes a resin.

[0013] (7) The battery module according to (5), wherein the third sealing portion includes metal.

[0014] (8) The battery module according to any one of (1) to (7), wherein the first support member and the second support member contain a resin.

[0015] (9) The battery module according to any one of (1) to (7), wherein the first support member and the second support member contain a metal.

[0016] (10) The battery module according to any one of (1) to (9), wherein the pouch has an internal pressure of 0.1 MPa or more and 3.0 MPa or less.

[0017] (11) The battery module according to any one of (1) to (10), wherein the elastic member further includes elastic foams disposed on both sides of the pouch in the stacking direction of the battery cells.

[0018] (12) The battery module according to any one of (1) to (11), wherein the battery cell includes a cell provided with a negative electrode mixture layer containing lithium metal or a lithium alloy, a solid electrolyte layer, and a positive electrode mixture layer. [Effects of the Invention]

[0019] According to the present invention, it is possible to provide a battery module capable of suppressing positional displacement of the elastic member in a direction perpendicular to the stacking direction of battery cells. [Brief Description of the Drawings]

[0020] [Figure 1] It is a side view showing a battery module according to one embodiment of the present invention. [Figure 2A] It is a partially enlarged perspective view of the battery module of Figure 1. [Figure 2B] It is a schematic diagram showing a cross section taken along line A-A of Figure 2A. [Figure 2C] It is a schematic diagram showing a cross section taken along line B-B of Figure 2A. [Figure 3A] It is a partially enlarged perspective view of a modified example of the battery module of Figure 2A. [Figure 3B] Figure 3A is a schematic diagram showing a cross-section along line BB. [Figure 4] Figure 2B is a schematic diagram showing a cross-section of a modified battery module. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described below with reference to the drawings.

[0022] [Battery Module] Figure 1 shows a battery module according to one embodiment of the present invention.

[0023] The battery module 10 comprises battery cell stacks 11A and 11B in which a plurality of battery cells 11 are stacked, end plates 12A and 12B provided at both ends of the battery cell stacks 11A and 11B in the stacking direction, and a center plate 12C provided between the battery cell stacks 11A and 11B. The battery module 10 also includes bind bars 13A and 13B between the end plates 12A and 12B to restrain the battery cell stacks 11A and 11B. The restraining pressure by the bind bars 13A and 13B is not particularly limited, but is, for example, 0.1 MPa or more and 3.0 MPa or less.

[0024] The battery module 10 has a first elastic member 14A positioned between a plurality of battery cells 11, and a second elastic member 14B positioned between the battery cell stack 11A and the end plate 12A and center plate 12C, and between the battery cells 11 and the end plate 12B and center plate 12C. In this case, since the second elastic member 14B is in contact with one battery cell 11, it is not particularly limited as long as it has more than half the elasticity of the first elastic member 14A, which is in contact with two battery cells 11. From the viewpoint of the energy density of the battery module 10, it is preferable that the second elastic member 14B has the same configuration as the first elastic member 14A except that its thickness is half, but it may also be identical to the first elastic member 14A.

[0025] As shown in Figures 2A and 2B, the first elastic member 14A comprises a pouch 20 containing gas, having a first sealing portion 21A and a second sealing portion 21B at both ends in the longitudinal direction (AA direction) perpendicular to the stacking direction of the battery cells 11, a first support member 22A that supports the entire area of ​​the first sealing portion 21A, and a second support member 22B that supports the entire area of ​​the second sealing portion 21B. Note that in Figure 2A, the battery cells 11 and the elastic foams 23A and 23B, which will be described later, are omitted from the description.

[0026] At this time, the first support member 22A and the second support member 22B are positioned by a positioning member installed on the battery module 10, for example.

[0027] The ratio of the thickness of the first support member 22A to the thickness of the pouch 20 and the ratio of the thickness of the second support member 22B to the thickness of the pouch 20 are, respectively, 0.20 or more and 3.5 or less, preferably 0.30 or more and 3.0 or less, and more preferably 0.46 or more and 1.0 or less. When the ratio of the thickness of the first support member 22A to the thickness of the pouch 20 and the ratio of the thickness of the second support member 22B to the thickness of the pouch 20 are, respectively, 0.20 or more and 3.5 or less, the pouch 20 can be positioned appropriately, and as a result, displacement of the first elastic member 14A in the direction perpendicular to the stacking direction of the battery cells 11 is suppressed. At this time, the ratio of the thickness of the first support member 22A to the thickness of the pouch 20 and the ratio of the thickness of the second support member 22B to the thickness of the pouch 20 include the state where the SOC is 0% and the state where the SOC is 100%.

[0028] Furthermore, in order for the battery module 10 to operate properly, the overall length of the battery module 10 is determined by the thickness of the battery module 10. In addition, the thickness of the pouch 20 is determined by the thickness of the battery module 10, and consequently, the thicknesses of the first support member 22A and the second support member 22B are determined. In this case, it is preferable that the thicknesses of the first support member 22A and the second support member 22B are less than or equal to the sum of the thicknesses of the first support member 22A and the second support member 22B, respectively.

[0029] In the longitudinal direction (AA direction) perpendicular to the stacking direction of the battery cells 11, the lengths of the first support member 22A and the second support member 22B are preferably less than or equal to the length of the pouch 20. This suppresses displacement of the first elastic member 14A in the direction perpendicular to the stacking direction of the battery cells 11. In this case, the ratio of the length of the first support member 22A to the length of the pouch 20 and the ratio of the length of the second support member 22B to the length of the pouch 20 are preferably 0.001 or more and 0.05 or less, and more preferably 0.005 or more and 0.044 or less.

[0030] The seal strength of the first sealing portion 21A and the seal strength of the second sealing portion 21B are preferably 1 N / mm or more, more preferably 2 N / mm or more, and even more preferably 3 N / mm or more. When the seal strength of the first sealing portion 21A and the seal strength of the second sealing portion 21B are 1 N / mm or more, peeling of the first sealing portion 21A and the second sealing portion 21B is suppressed, thereby improving the durability of the battery module 10. For example, the seal strength of the first sealing portion 21A and the seal strength of the second sealing portion 21B are 5 N / mm or less.

[0031] The seal strength is measured in accordance with JIS Z1701:2019.

[0032] As shown in Figure 2B, the first elastic member 14A further comprises elastic foams 23A and 23B positioned on both sides of the pouch 20 in the stacking direction of the battery cell 11. In this case, when the first elastic member 14A is compressed due to the expansion of the battery cell 11 during charging, the elastic foams 23A and 23B are interposed between the battery cell 11 and the pouch 20, thereby increasing the uniformity of the surface pressure of the first elastic member 14A.

[0033] As shown in Figure 2C, the pouch 20 has a third sealing portion 21C that extends in the longitudinal direction (AA direction) perpendicular to the stacking direction of the battery cells 11, and the third sealing portion 21C faces the battery cells 11. As a result, the battery cells 11 and the elastic foam 23B reinforce the third sealing portion 21C, thereby improving the durability of the battery module 10. In this case, the third sealing portion 21C is formed on one side of the pouch 20 that faces the battery cells 11, but it may also be formed on both sides of the pouch 20 that face the battery cells 11.

[0034] The pouch 20 is not particularly limited as long as it is elastic and can follow the expansion and contraction associated with the charging and discharging of the battery cell 11 and can be sealed, but for example, the aluminum film is sandwiched between stretchable resin films. The stretchable resin is not particularly limited, but examples include polypropylene, polyamide, and polyester.

[0035] The method for forming the first sealing portion 21A, the second sealing portion 21B, and the third sealing portion 21C is not particularly limited, but one method is to heat-seal the stretchable resin constituting the pouch 20. Alternatively, metal welding may be used when forming the third sealing portion 21C. This reinforces the third sealing portion 21C, thereby improving the durability of the battery module 10.

[0036] The internal pressure of the pouch 20 is preferably 0.1 MPa or more and 3.0 MPa or less, and more preferably 0.1 MPa or more and 2.5 MPa or less. When the internal pressure of the pouch 20 is 0.1 MPa or more, the uniformity of the surface pressure of the first elastic member 14A is increased, and when it is 3.0 MPa or less, damage to the pouch 20 is more easily suppressed even if the battery cells 11 expand and contract as the battery cells 11 are charged and discharged.

[0037] The pouch 20 is not particularly limited, but an example is a pillow pouch (commercially available). The gas sealed in the pouch 20 is not particularly limited, but an example is air.

[0038] Alternatively, instead of pouch 20, a pouch may be used that has a first sealing portion 21A and a second sealing portion 21B at both ends in the longitudinal direction (AA direction) perpendicular to the stacking direction of the battery cells 11, and has sealing portions other than the third sealing portion 21C. Specifically, a pouch may be used that has a first sealing portion 21A and a second sealing portion 21B at both ends in the longitudinal direction (AA direction) perpendicular to the stacking direction of the battery cells 11, and a third sealing portion 21D and a fourth sealing portion 21E at both ends in the short direction (BB direction) perpendicular to the stacking direction of the battery cells 11 (see Figures 3A and 3B). Here, the sealing strength of the first sealing portion 21A, the second sealing portion 21B, the third sealing portion 21D, and the fourth sealing portion 21E is, for example, 5 N / mm.

[0039] The materials constituting the first support member 22A and the second support member 22B are not particularly limited. Among these, resin is preferred from the viewpoint of the energy density of the battery module 10. On the other hand, metal is preferred from the viewpoint of the durability of the battery module 10.

[0040] The Poisson's ratio of the elastic foams 23A and 23B is preferably 0.3 or less. When the Poisson's ratio of the elastic foams 23A and 23B is 0.3 or less, the elastic foams 23A and 23B can more easily absorb the change in thickness due to the expansion and contraction of the battery cell 11. For example, the Poisson's ratio of the elastic foams 23A and 23B is 0.01 or more.

[0041] The thickness of the elastic foams 23A and 23B when the battery cell is charged to 100% is not particularly limited, but is, for example, 0.05 mm or more and 0.4 mm or less.

[0042] The porosity of the elastic foams 23A and 23B is not particularly limited, but is, for example, 30% to 95%. The materials constituting the elastic foams 23A and 23B are not particularly limited, but include, for example, polyurethane, silicone resin, ethylene propylene rubber, styrene resin, olefin resin, polyamide, and polyester.

[0043] The method for fixing the elastic foams 23A and 23B to the pouch 20 is not particularly limited, but one example is to adhere the elastic foams 23A and 23B to the pouch 20 with an elastic adhesive.

[0044] Furthermore, as shown in Figure 4, the first elastic member 14A may have a portion of the first sealing portion 21A and a portion of the second sealing portion 21B facing the battery cell 11. This ensures that uniform pressure is applied across the entire surface of the pouch 20, reducing stress concentration at the battery cell 11-side ends of the first sealing portion 21A and the second sealing portion 21B, thereby improving the durability of the battery module 10. In this case, the ratio of the length of the portion of the first sealing portion 21A (or the portion of the second sealing portion 21B) facing the battery cell 11 to the length of the pouch 20 in the AA direction is not particularly limited, but is, for example, 0.001 or more and 0.005 or less.

[0045] [cell] The cells constituting the battery cell 11 are not particularly limited, but examples include solid battery cells such as all-solid-state battery cells and semi-solid-state battery cells, and non-aqueous electrolyte battery cells having a negative electrode composite layer containing lithium metal or lithium alloy. The elements other than lithium that constitute the lithium alloy are not particularly limited, but examples include Sn, Ag, Mg, In, Si, and Al. Among these, from the viewpoint of energy density, a cell comprising a negative electrode composite layer containing lithium metal or lithium alloy, a solid electrolyte layer, and a positive electrode composite layer is preferred.

[0046] The following describes an example of an all-solid-state battery cell.

[0047] An all-solid-state battery cell comprises a negative electrode current collector, a negative electrode composite layer containing lithium metal or a lithium alloy, a solid electrolyte layer, a positive electrode composite layer, and a positive electrode current collector. All-solid-state battery cells are generally prone to misalignment of the pouch 20 in a direction perpendicular to the stacking direction of the battery cells 11, and are therefore preferably applied to a battery module 10.

[0048] The material constituting the negative electrode current collector is not particularly limited, and examples thereof include silver, palladium, gold, platinum, aluminum, copper, nickel, stainless steel, and carbon. Among these, copper, stainless steel and nickel are preferred from the viewpoints of electrical conductivity and cost.

[0049] The shape of the negative electrode current collector is not particularly limited, and examples thereof include a foil shape, a plate shape, a mesh shape, a non-woven fabric shape, and a foam shape.

[0050] The solid electrolyte constituting the solid electrolyte layer is not particularly limited, and examples thereof include a sulfide solid electrolyte and an oxide solid electrolyte.

[0051] The form of the solid electrolyte is not particularly limited, and examples thereof include particles.

[0052] The content of the solid electrolyte in the solid electrolyte layer is not particularly limited, and is, for example, 50 mass% or more and 99 mass% or less.

[0053] The solid electrolyte layer may further contain a binder or the like.

[0054] The method for forming the solid electrolyte layer is not particularly limited, and examples thereof include a method of applying a slurry containing a solid electrolyte and a solvent.

[0055] The positive electrode mixture layer contains a positive electrode active material. The positive electrode active material is not particularly limited, and examples thereof include lithium cobaltate (LiCoO₂), lithium nickelate (LiNiO₂), LiNi p Mn q Co r O₂ (p+q+r=1), LiNi p Al q Co r O₂ (p+q+r=1), lithium manganate (LiMn₂O₄), Li 1+x Mn 2-x-y M yExamples include O4(x+y=2) (where M is one or more elements selected from the group consisting of Al, Mg, Co, Fe, Ni, and Zn), lithium titanate, and LiMPO4 (where M is one or more elements selected from the group consisting of Fe, Mn, Co, and Ni).

[0056] The content of the positive electrode active material in the positive electrode composite layer is not particularly limited, but for example, it is 50% by mass or more and 99% by mass or less.

[0057] The positive electrode composite layer may further contain a solid electrolyte. The solid electrolyte is not particularly limited as long as it is capable of conducting lithium ions, but examples include oxide solid electrolytes and sulfide solid electrolytes.

[0058] The positive electrode composite layer may further contain a binder, a conductive additive, and the like.

[0059] The method for forming the positive electrode composite layer is not particularly limited, but one example is a method of applying a slurry containing a positive electrode active material and a solvent.

[0060] The materials used to constitute the positive electrode current collector are not particularly limited, but examples include aluminum, aluminum alloys, stainless steel, nickel, iron, and titanium. Among these, aluminum, aluminum alloys, and stainless steel are preferred.

[0061] The shape of the positive electrode current collector is not particularly limited, but examples include foil-shaped and plate-shaped.

[0062] Although embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and the above embodiments may be modified as appropriate within the scope of the spirit of the present invention. For example, the first elastic member 14A may have a first sealing portion 21A and a second sealing portion 21B at both ends in the short direction (BB direction) perpendicular to the stacking direction of the battery cell 11. [Explanation of symbols]

[0063] 10 Battery Modules 11 battery cells 11A, 11B battery cell stack 12A, 12B end plates 12C Center Plate 13A, 13B Bind Bar 14A First elastic member 14B Second Elastic Member 20 pouches 21A 1st sealing part 21B 2nd sealing part 21C, 21D 3rd sealing part 21E 4th sealing part 22A First support member 22B Second support member 23A, 23B Elastic foam

Claims

1. A battery cell stack in which multiple battery cells are stacked, The battery comprises an elastic member disposed between the plurality of battery cells, The elastic member comprises a pouch containing gas, having a first sealing portion and a second sealing portion at both ends in a direction perpendicular to the stacking direction of the battery cells, a first support member supporting at least a portion of the first sealing portion, and a second support member supporting at least a portion of the second sealing portion. A battery module in which the ratio of the thickness of the first support member to the thickness of the pouch and the ratio of the thickness of the second support member to the thickness of the pouch are, each, 0.2 or more and 3.5 or less.

2. The battery module according to claim 1, wherein in a direction perpendicular to the stacking direction of the battery cells, the length of the first support member and the length of the second support member are less than or equal to the length of the pouch.

3. The battery module according to claim 1 or 2, wherein the seal strength of the first sealing portion and the seal strength of the second sealing portion are 1 N / mm or more.

4. The battery module according to claim 1 or 2, wherein a portion of the first sealing portion and a portion of the second sealing portion of the first elastic member face the battery cell.

5. The pouch has a third sealing portion that extends in a direction perpendicular to the stacking direction of the battery cells, The battery module according to claim 1 or 2, wherein the third sealing portion faces the battery cell.

6. The battery module according to claim 5, wherein the third sealing portion includes a resin.

7. The battery module according to claim 5, wherein the third sealing portion includes metal.

8. The battery module according to claim 1 or 2, wherein the first support member and the second support member include resin.

9. The battery module according to claim 1 or 2, wherein the first support member and the second support member include metal.

10. The battery module according to claim 1 or 2, wherein the pouch has an internal pressure of 0.1 MPa or more and 3.0 MPa or less.

11. The battery module according to claim 1 or 2, wherein the elastic member further comprises elastic foam disposed on both sides of the pouch in the stacking direction of the battery cells.

12. The battery module according to claim 1 or 2, wherein the battery cell comprises a negative electrode composite layer containing lithium metal or lithium alloy, a solid electrolyte layer, and a positive electrode composite layer.

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