Battery module

Abstract

This provides a battery module that can suppress damage to the pouch. [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 has a third sealing portion 21C at one end in a direction perpendicular to the stacking direction of the battery cells 11, and elastic foams 23A and 23B disposed on both sides of the pouch 20 in the stacking direction of the battery cells 11. The end E of the third sealing portion 21C is folded back so that it is sandwiched between the unsealed portion 21E of the pouch 20 and the elastic foam 23A.

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, the fluid-containing bag is prone to damage because the battery cells expand and contract as they charge and discharge.

[0006] The present invention aims to provide a battery module that can suppress damage to the pouch. [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 having a sealing portion at one end in a direction perpendicular to the stacking direction of the battery cells and containing gas, and elastic foam disposed on both sides of the pouch in the stacking direction of the battery cells, wherein the sealing portion is folded back so that the end of the sealing portion is sandwiched between the unsealed portion of the pouch and the elastic foam.

[0008] (2) The battery module as described in (1), wherein the sealing portion has a seal width of 40 mm or more.

[0009] (3) The battery module according to (1) or (2), wherein the battery cell comprises a positive electrode composite layer and an insulating frame disposed around at least a portion of the positive electrode composite layer, and the folded-over region of the sealing portion faces the insulating frame and does not face the positive electrode composite layer.

[0010] (4) The pouch is a battery module according to any one of items (1) to (3), wherein the internal pressure is 0.1 MPa or more and 3.0 MPa or less.

[0011] (5) The battery module according to any one of (1) to (4), wherein the battery cell includes a cell having a negative electrode composite layer containing lithium metal or lithium alloy.

[0012] (6) The battery module according to any one of (1) to (5), wherein the battery cell includes a solid battery cell. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a battery module that can suppress damage to the pouch. [Brief explanation of the drawing]

[0014] [Figure 1]It is a side view showing a battery module according to an 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 diagram showing the surface pressure distribution when a pressure of 1 MPa is applied to the pouch of Figure 2C. [Figure 3B] It is a diagram showing the surface pressure distribution when a pressure of 2.5 MPa is applied to the pouch of Figure 2C. [Mode for Carrying Out the Invention]

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0016] [Battery Module] Figure 1 shows a battery module according to an embodiment of the present invention.

[0017] The battery module 10 includes 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 in the stacking direction of the battery cell stacks 11A and 11B, and a center plate 12C provided between the battery cell stacks 11A and 11B. The battery module 10 further includes bind bars 13A and 13B that restrain the battery cell stacks 11A and 11B between the end plates 12A and 12B. The restraining pressure by the bind bars 13A and 13B is not particularly limited, and is, for example, 1.0 MPa or more and 2.5 MPa or less.

[0018] 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.

[0019] As shown in Figures 2A and 2C, the elastic member 14A comprises a pouch 20 containing gas and having a third sealing portion 21C at one end in the short direction (BB direction) perpendicular to the stacking direction of the battery cells 11, and elastic foams 23A and 23B positioned on both sides of the pouch 20 in the stacking direction of the battery cells 11. In this case, the end E of the third sealing portion 21C is folded back so that it is sandwiched between the unsealed portion 21D of the pouch 20 and the elastic foam 23A. As a result, the end E of the third sealing portion 21C is reinforced, and damage to the pouch 20 is suppressed even if the battery cells 11 expand and contract due to charging and discharging of the battery cells 11. Note that in Figure 2A, the battery cells 11 and elastic foams 23A and 23B are not shown.

[0020] At this time, as the 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, and the end E of the third sealing portion 21C is in contact with the elastic foam 23A, thus increasing the uniformity of the surface pressure of the elastic member 14A.

[0021] Figures 3A and 3B show the surface pressure distribution when pouch 20 is subjected to pressures of 1 MPa and 2.5 MPa, respectively. A compression-recovery test was performed using a universal material testing machine (Instron), and the surface pressure on the side of pouch 20 where the third sealing portion 21C is not folded was measured using a tactile sensor 5027 (Tekscan).

[0022] Figures 3A and 3B show that the uniformity of surface pressure is high regardless of whether the pressure applied to pouch 20 is 1 MPa or 2.5 MPa.

[0023] The seal width of the third sealing portion 21C, that is, the length of the third sealing portion 21C in the shorter direction (BB direction) before it is folded back, is preferably 40 mm or more. When the seal width of the third sealing portion 21C is 40 mm or more, the end E of the third sealing portion 21C is more easily reinforced, and the permeation of the gas sealed in the pouch 20 is suppressed.

[0024] When the battery cell 11 comprises a positive electrode composite layer and an insulating frame positioned around at least a portion of the positive electrode composite layer, it is preferable that the folded region of the third sealing portion 21C faces the insulating frame but not the positive electrode composite layer. This improves the uniformity of the surface pressure of the elastic member 14A.

[0025] The internal pressure of the pouch 20 is preferably between 0.1 MPa and 3.0 MPa, and more preferably between 1.0 MPa and 2.5 MPa. When the internal pressure of the pouch 20 is 0.1 MPa or higher, the uniformity of the surface pressure of the elastic member 14A is increased, and when it is 3.0 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.

[0026] 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. In this case, 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 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.

[0028] 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.

[0029] The gas sealed in pouch 20 is not particularly limited, but air is one example.

[0030] The materials constituting the first support member 22A and the second support member 22B are not particularly limited, but include resin and metal.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] [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.

[0036] The following describes an example of an all-solid-state battery cell.

[0037] 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.

[0038] 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 conductivity and cost.

[0039] 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.

[0040] 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.

[0041] The form of the solid electrolyte is not particularly limited, and examples thereof include particles.

[0042] 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.

[0043] The solid electrolyte layer may further contain a binder and the like.

[0044] 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.

[0045] 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).

[0046] 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.

[0047] 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.

[0048] The positive electrode composite layer may further contain a binder, a conductive additive, and the like.

[0049] 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.

[0050] 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.

[0051] The shape of the positive electrode current collector is not particularly limited, but examples include foil-shaped and plate-shaped.

[0052] 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]

[0053] 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 21D Unsealed part 22A First support member 22B Second support member 23A, 23B Elastic foam E end

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 having a sealing portion at one end in a direction perpendicular to the stacking direction of the battery cells and containing gas, and elastic foams arranged on both sides of the pouch in the stacking direction of the battery cells. The battery module is characterized in that the sealing portion is folded back so that its end is sandwiched between the unsealed portion of the pouch and the elastic foam.

2. The battery module according to claim 1, wherein the sealing portion has a seal width of 40 mm or more.

3. The battery cell comprises a positive electrode composite layer and an insulating frame disposed around at least a portion of the positive electrode composite layer. The battery module according to claim 1 or 2, wherein the folded-over region of the sealing portion faces the insulating frame and does not face the positive electrode composite layer.

4. 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.

5. 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.

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

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