Battery module

Abstract

The present invention provides a battery module that can achieve high uniformity of surface pressure on elastic members. [Solution] The battery module comprises a battery cell stack in which a plurality of battery cells 11 are stacked, and an elastic member 14A disposed between the plurality of battery cells 11. The elastic member 14A comprises a pouch 20 in which gas is sealed, and elastic foams 23A and 23B disposed on both sides of the pouch 20 in the stacking direction of the battery cells 11. When a surface pressure of 1.0 MPa to 2.5 MPa is applied to the elastic foams 23A and 23B, respectively, and the surface pressure [MPa] is plotted against the compressive strain [%], the slope of the surface pressure with respect to the compressive strain [MPa / %] is 0.030 to 0.231.

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 bag described in Patent Document 1 is placed between multiple battery cells, air can enter between the fluid-containing bag and the battery cells, which tends to reduce the uniformity of the surface pressure.

[0006] The present invention aims to provide a battery module that can achieve high uniformity of surface pressure of elastic members. [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 first elastic member and second elastic members disposed on both sides of the first elastic member in the stacking direction of the battery cells, the second elastic member being an elastic foam, and when a surface pressure of 1 MPa to 2.5 MPa is applied to the elastic foam, the slope of the surface pressure with respect to the compressive strain [MPa / %] is 0.030 to 0.231.

[0008] (2) The battery module according to (1), wherein the compressive strain when a surface pressure of 1 MPa is applied to the elastic foam is 30.0% or more and 98.5% or less.

[0009] (3) The battery module according to (1) or (2), wherein the compressive strain when a surface pressure of 2.5 MPa or less is applied to the elastic foam is 60.0% or more and 98.5% or less.

[0010] (4) The battery module according to any one of (1) to (3), wherein the elastic foam is an open-cell foam.

[0011] (5) The battery module according to any one of (1) to (4), wherein the elastic member has a thickness of 3 mm or less.

[0012] (6) The battery module according to any one of (1) to (5), wherein the first elastic member is a pouch containing gas.

[0013] (7) The battery module according to (6), wherein the pouch has a sealing portion that extends in a direction perpendicular to the stacking direction of the battery cells, and the sealing portion is in contact with the elastic foam.

[0014] (8) The battery module according to (6) or (7), wherein the pouch has an internal pressure of 0.1 MPa or more and 3.0 MPa or less.

[0015] (9) The battery module according to any one of (1) to (8), wherein the battery cell includes a cell provided with a negative electrode mixture layer containing lithium metal or a lithium alloy.

[0016] (10) The battery module according to any one of (1) to (9), wherein the battery cell includes a solid-state battery cell. Effects of the Invention

[0017] According to the present invention, it is possible to provide a battery module capable of increasing the uniformity of the surface pressure of the elastic member. Brief Description of the Drawings

[0018] [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 3] It is a schematic diagram showing a cross section of a modified example of the battery module of Figure 2B. Modes for Carrying Out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0020] [Battery Module] Figure 1 shows a battery module according to one embodiment of the present invention.

[0021] 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, 1.0 MPa or more and 2.5 MPa or less.

[0022] The battery module 10 has elastic members 14A positioned between multiple battery cells 11, and elastic members 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 elastic member 14B is in contact with one battery cell 11, it is not particularly limited as long as it has at least half the elasticity of the elastic member 14A that 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 elastic member 14B has the same configuration as the elastic member 14A except that its thickness is about half, but it may also be identical to the elastic member 14A.

[0023] As shown in Figures 2A, 2B, and 2C, the elastic member 14A comprises a pouch 20 containing gas as a first elastic member, and elastic foams 23A and 23B as second elastic members positioned on both sides of the pouch 20 in the stacking direction of the battery cells 11. When the elastic member 14A is compressed due to the expansion of the battery cells 11 during charging, the elastic foams 23A and 23B are interposed between the battery cells 11 and the pouch 20, thereby increasing the uniformity of the surface pressure of the elastic member 14A. Note that in Figure 2A, the battery cells 11 and the elastic foams 23A and 23B are omitted from the description.

[0024] When elastic foams 23A and 23B are subjected to a surface pressure of 1.0 MPa to 2.5 MPa, respectively, and the surface pressure [MPa] is plotted against compressive strain [%], the slope of the surface pressure with respect to compressive strain [MPa / %] is preferably between 0.037 and 0.067, and between 0.037 and 0.067. Because the slope of the surface pressure with respect to compressive strain [MPa / %] is between 0.030 and 0.231, the uniformity of the surface pressure of the elastic member 14A is increased.

[0025] The compressive strain of elastic foams 23A and 23B is measured in accordance with JIS K 6262.

[0026] When a surface pressure of 1.0 MPa is applied to the elastic foams 23A and 23B, the compressive strain is preferably 30.0% to 92.0%, and more preferably 30.0% to 76.0%. When the compressive strain when a surface pressure of 1.0 MPa is applied to the elastic foams 23A and 23B is 30.0% to 92.0%, the uniformity of the surface pressure of the elastic member 14A is increased.

[0027] It is preferable that the compressive strain of the elastic foams 23A and 23B when a surface pressure of 2.5 MPa or less is applied to each is 60.0% to 98.5%, and more preferably 71.0% to 98.5%. When the compressive strain of the elastic foams 23A and 23B when a surface pressure of 2.5 MPa or less is applied to each is 60.0% to 98.5%, the uniformity of the surface pressure of the elastic member 14A is increased.

[0028] The elastic foams 23A and 23B are preferably open-cell foams. This improves the uniformity of the surface pressure of the elastic member 14A.

[0029] 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.

[0030] The thickness of the elastic member 14A is preferably 6 mm or less, and more preferably 3 mm or less. When the thickness of the elastic member 14A is 3 mm or less, the energy density of the battery module 10 increases. The thickness of the elastic member 14A is, for example, 2.5 mm or more.

[0031] Here, the thickness of pouch 20 when the restraining pressure is 1.0 MPa is not particularly limited, but for example, it is between 1 mm and 5 mm. The thickness of elastic foams 23A and 23B when the restraining pressure is 1.0 MPa is not particularly limited, but for example, it is between 0.02 mm and 3 mm.

[0032] The internal pressure of the pouch 20 is preferably 0.1 MPa to 3.0 MPa, and preferably 1.0 MPa to 2.5 MPa. When the internal pressure of the pouch 20 is 1.0 MPa or higher, the uniformity of the surface pressure of the elastic member 14A is increased, and when it is 2.5 MPa or lower, damage to the pouch 20 is suppressed even if the battery cells 11 expand and contract as the battery cells 11 are charged and discharged.

[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 is in contact with the elastic foam 23B. This increases the uniformity of the surface pressure of the elastic member 14A.

[0034] As shown in Figure 2B, the pouch 20 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. In this case, the elastic member 14A further comprises 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. Furthermore, 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.

[0035] 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.

[0036] 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.

[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.

[0039] The materials constituting the first support member 22A and the second support member 22B are not particularly limited, but include resin and metal.

[0040] There are no particular limitations on the method for fixing the elastic foam 23A (or 23B) to the pouch 20, but one example is to adhere the elastic foam 23A (or 23B) to the pouch 20 with an elastic adhesive.

[0041] A corrugated leaf spring 40 may be used as the first elastic member (see Figure 3). Alternatively, a laminate of the pouch 20 and the corrugated leaf spring 40 may be used as the first elastic member. Preferably, the corrugated leaf spring 40 contains fiber-reinforced plastic (FRP). This ensures that the corrugated leaf spring 50 has both heat resistance and heat insulation properties. Examples of FRP include carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP).

[0042] The method for fixing the corrugated leaf spring 40 is not particularly limited, but one example is to bond the corrugated leaf spring 40 with an elastic adhesive. The corrugated leaf spring 40 is manufactured, for example, by a press molding method.

[0043] [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, solid battery cells having a negative electrode composite layer containing lithium metal or lithium alloy are preferred from the viewpoint of energy density.

[0044] The following describes an example of an all-solid-state battery cell.

[0045] 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.

[0046] The materials that make up the negative electrode current collector are not particularly limited, but examples include silver, palladium, gold, platinum, aluminum, copper, nickel, stainless steel, and carbon. Among these, copper, stainless steel, and nickel are preferred from the viewpoint of conductivity and cost.

[0047] 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.

[0048] 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.

[0049] The form of the solid electrolyte is not particularly limited, and examples thereof include particles.

[0050] 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.

[0051] The solid electrolyte layer may further contain a binder and the like.

[0052] 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.

[0053] 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 y O₄ (x+y=2) (wherein M is one or more elements selected from the group consisting of Al, Mg, Co, Fe, Ni and Zn), lithium titanate, and LiMPO₄ (wherein M is one or more elements selected from the group consisting of Fe, Mn, Co and Ni).

[0054] The content of the positive electrode active material in the positive electrode mixture layer is not particularly limited, and is, for example, 50 mass% or more and 99 mass% or less.

[0055] 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.

[0056] The positive electrode composite layer may further contain a binder, a conductive additive, and the like.

[0057] 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.

[0058] 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.

[0059] The shape of the positive electrode current collector is not particularly limited, but examples include foil-shaped and plate-shaped.

[0060] 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. [Explanation of symbols]

[0061] 10 Battery Modules 11 battery cells 11A, 11B battery cell stack 12A, 12B end plates 12C Center Plate 13A, 13B Bind Bar 14A, 14B Elastic members 20 pouches 21A 1st sealing part 21B 2nd sealing part 21C 3rd sealing part 22A First support member 22B Second support member 23A, 23B Elastic foam 40. Corrugated leaf spring

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 first elastic member and second elastic members arranged on both sides of the first elastic member in the stacking direction of the battery cells. The second elastic member is an elastic foam, A battery module in which, when a surface pressure of 1 MPa to 2.5 MPa is applied to the elastic foam, the slope of the surface pressure [MPa / %] with respect to the compressive strain is 0.030 to 0.231 when the surface pressure [MPa] is plotted against the compressive strain [%].

2. The battery module according to claim 1, wherein the compressive strain when a surface pressure of 1.0 MPa is applied to the elastic foam is 30.0% or more and 92.0% or less.

3. The battery module according to claim 1 or 2, wherein the compressive strain when a surface pressure of 2.5 MPa or less is applied to the elastic foam is 60.0% or more and 98.5% or less.

4. The battery module according to claim 1 or 2, wherein the elastic foam is an open-cell foam.

5. The battery module according to claim 1 or 2, wherein the elastic member has a thickness of 3 mm or less.

6. The battery module according to claim 1 or 2, wherein the first elastic member is a pouch containing gas.

7. The pouch has a sealing portion that extends in a direction perpendicular to the stacking direction of the battery cells, The battery module according to claim 6, wherein the sealing portion is in contact with the elastic foam.

8. The battery module according to claim 6, wherein the pouch has an internal pressure of 0.1 MPa or more and 3.0 MPa or less.

9. The battery module according to claim 1 or 2, wherein the battery cell includes a cell having a negative electrode composite layer containing lithium metal or a lithium alloy.

10. The battery module according to claim 1 or 2, wherein the battery cell includes a solid battery cell.

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