Storage battery module and corrugated plate spring

Abstract

The problem to be solved by the present invention is to provide a battery module comprising: a battery cell laminate in which a plurality of battery cells are laminated; a pair of plate-like members provided at both ends of the battery cell laminate in the lamination direction; and a buffer material disposed between the plurality of battery cells and / or between the battery cell laminate and the plate-shaped member. Furthermore, the buffer material is provided with a wave-shaped plate spring in which concave parts and convex parts are alternately and continuously arranged and which extends in a predetermined direction. The corrugated leaf spring has a laminated structure in which layers containing glass fibers and layers containing epoxy resin are alternately laminated in the thickness direction, or a laminated structure in which layers containing glass fibers and / or epoxy resin are laminated in the thickness direction. A layer containing a styrene block copolymer or a cycloolefin polymer is present between the laminated layers.

Description

Technical Field

[0001] The invention relates to a battery module and a corrugated leaf spring. Background Art

[0002] In recent years, research and development of secondary batteries that contribute to improving energy efficiency have been conducted in order to ensure that the majority of people have access to affordable, reliable, sustainable, and advanced energy.

[0003] A battery module, for example, includes a battery cell stack composed of a plurality of stacked battery cells. Since battery cells expand and contract during charging and discharging, the battery module includes, for example, a pair of end plates disposed at both ends of the battery cell stack in the stacking direction, and binding rods that constrain the battery cell stack between the end plates.

[0004] Patent Document 1 describes a power storage device comprising: a power storage module comprising a plurality of power storage cells stacked in a stacking direction; a housing housing the power storage module; and a restraining member disposed between the power storage cells. The restraining member comprises a first flat plate and a second flat plate spaced apart in the stacking direction, and a corrugated plate disposed between the first and second flat plates.

[0005] [Prior Art Literature]

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2022-156427 Summary of the Invention

[0008] [Problems to be solved by the invention]

[0009] However, in the power storage device described in Reference 1, as the power storage cells expand during charging, when the restriction unit is compressed, the difference in surface pressure between the portions of the first and second flat plates that are in contact with the corrugated plate and the portions of the first and second flat plates that are not in contact with the corrugated plate increases, thereby reducing the uniformity of the surface pressure of the restriction unit.

[0010] Furthermore, in the power storage device described in Reference 1, if a corrugated plate made of glass fiber reinforced epoxy resin is used, when the restriction unit is compressed due to expansion of the power storage cells during charging, breakage occurs between the glass fiber and epoxy resin constituting the corrugated plate, or the epoxy resin breaks, thereby reducing the strength of the restriction unit.

[0011] An object of the present invention is to provide a battery module capable of improving the uniformity of surface pressure and strength of a buffer material.

[0012] [Technical means to solve the problem]

[0013] (1) A battery module comprising: a battery cell stack having a plurality of battery cells stacked thereon; a pair of plate-like components disposed at both ends of the battery cell stack in a stacking direction; and a buffer material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-like components; wherein the buffer material comprises a corrugated leaf spring having concave portions and convex portions alternately and continuously disposed and extending in a predetermined direction, the corrugated leaf spring having a laminated structure in which layers containing glass fiber and layers containing epoxy resin are alternately laminated in a thickness direction, or a laminated structure in which layers containing glass fiber and / or epoxy resin are laminated in a thickness direction, and a layer containing a styrene block copolymer or a cycloolefin polymer is present between the laminated layers.

[0014] (2) The battery module according to (1), wherein the buffer material comprises a plurality of corrugated leaf springs stacked in a stacking direction of the battery cell stack, and the concave portions and convex portions of adjacent corrugated leaf springs face and contact each other.

[0015] (3) The battery module according to (1) or (2), wherein the battery cells are solid battery cells.

[0016] (4) A corrugated leaf spring in which concave portions and convex portions are alternately and continuously arranged and extend in a predetermined direction, the corrugated leaf spring having a laminated structure in which layers containing glass fiber and layers containing epoxy resin are alternately laminated in the thickness direction, or a laminated structure in which layers containing glass fiber and / or epoxy resin are laminated in the thickness direction, and a layer containing a styrene block copolymer or a cycloolefin polymer is present between the laminated layers.

[0017] (Effects of the Invention)

[0018] According to the present invention, a battery module can be provided that can improve the uniformity of the surface pressure and the strength of the buffer material. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 FIG. 1 is a cross-sectional view of a battery module according to one embodiment of the present invention.

[0020] Figure 2 yes Figure 1 A partial enlarged view of the battery module.

[0021] Figure 3 yes Figure 2 An enlarged view of the corrugated leaf spring.

[0022] Figure 4 yes Figure 3 A partial enlarged view of the corrugated leaf spring.

[0023] Figure 5 yes Figure 3 A partially enlarged view of a variation of the wavy leaf spring.

[0024] Figure 6 This is a graph showing the relationship between the Young's modulus and the allowable strain of the test specimens of Example 1 and Comparative Example 1.

[0025] Figure 7 This is a graph showing the measurement results of the impact reaction force of the test pieces of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0027] Figure 1 A battery module according to one embodiment of the present invention is shown.

[0028] The battery module 10 includes a battery cell stack 11 comprising a plurality of stacked battery cells 11a; a pair of plate-shaped end plates 12 disposed at both ends of the battery cell stack 11 in the stacking direction; and binding rods 13 serving as restraining members for restraining the battery cell stack 11 between the pair of end plates 12. The binding rods 13 are disposed at both the upper and lower portions of the battery cell stack in the figure.

[0029] In the battery module 10 , cushioning materials 14 are arranged between the plurality of battery cells 11 a and between the battery cell stack 11 and the end plates 12 .

[0030] Furthermore, the buffer material 14 may be disposed between the plurality of battery cells 11 a or between the battery cell stack 11 and the end plate 12 .

[0031] like Figure 2 As shown, the cushioning material 14 includes a pair of first elastic members 14a disposed on both outer sides of the battery cell stack 11 in the stacking direction, and a second elastic member 14b disposed between the pair of first elastic members 14a. Furthermore, the second elastic member 14b is formed by stacking four layers of corrugated leaf springs W in the stacking direction of the battery cell stack 11. This reduces hysteresis loss in the cushioning material 14.

[0032] Here, as the battery cell 11a expands during charging and the buffer material 14 is compressed, the first elastic member 14a is interposed between the battery cell 11a and the second elastic member 14b. Therefore, the surface pressure difference between the portion of the first elastic member 14a that contacts the second elastic member 14b and the portion of the first elastic member 14a that does not contact the second elastic member 14b is reduced, thereby improving the uniformity of the surface pressure.

[0033] like Figure 3 As shown, the corrugated leaf spring W has concave portions R and convex portions C arranged alternately and continuously, extending in the depth direction of the figure. Furthermore, the second elastic member 14b faces and contacts the concave portions R and convex portions C of adjacent corrugated leaf springs W. Furthermore, the concave portions R and convex portions C protrude downward and upward, respectively, in the stacking direction of the battery cell stack 11.

[0034] like Figure 4 As shown, the corrugated leaf spring W has a laminated structure consisting of first layers 41 composed of glass fiber and second layers 42 composed of epoxy resin alternately stacked in the thickness direction. A third layer 43 composed of a styrene block copolymer or cycloolefin polymer is located between the stacked first and second layers 41, 42. Because the styrene block copolymer or cycloolefin polymer has high adhesion and flexibility to the glass fiber and epoxy resin, when the buffer material 14 is compressed due to the expansion of the battery cells 11a during charging, the first and second layers 41, 42 of the corrugated leaf spring W are not only less likely to break, but the second layer 42 is also less likely to break, thereby improving the strength of the buffer material 14. Furthermore, the corrugated leaf spring W is manufactured, for example, by stamping.

[0035] The first layer 41 comprising glass fibers is not particularly limited, and for example, a fabric made of glass fiber yarns can be used. The glass fibers may be surface-treated with a silane coupling agent. This further increases the strength of the buffer material 14.

[0036] The epoxy resin contained in the second layer 42 is not particularly limited, and an example thereof is bisphenol A.

[0037] The mass ratio of the glass fiber to the epoxy resin in the corrugated leaf spring W is not particularly limited, but is, for example, 20% to 80%.

[0038] The styrene block copolymer contained in the third layer 43 is not particularly limited, and examples thereof include styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene-propylene-styrene block copolymer (SEPS), and styrene-ethylene-butylene-styrene block copolymer (SEBS). Among them, copolymers having a block structure of polystyrene and polyisoprene are preferred.

[0039] The cycloolefin polymer contained in the third layer 43 may be a single polymer or a copolymer, and is not particularly limited.

[0040] The content of the styrene block copolymer or the cycloolefin polymer in the corrugated leaf spring W is not particularly limited, but is, for example, 0.3% by mass or more and 15% by mass or less.

[0041] The corrugated leaf spring W is obtained, for example, by mixing bisphenol A with a styrene block copolymer or a cycloolefin polymer in a solvent, laminating a prepreg obtained by impregnating a fabric made of glass fiber threads in a liquid obtained by removing the solvent, and then performing press molding.

[0042] The number of stacked first layers 41 is not particularly limited, and is, for example, 2 or more and 80 or less.

[0043] In addition, if Figure 5 As shown, the corrugated leaf spring W has a laminated structure in which first layers 51 containing glass fiber and epoxy resin are laminated in the thickness direction. Second layers 52 containing styrene block copolymer or cycloolefin polymer may be present between the laminated first layers 51 .

[0044] The first layer 51 including glass fiber and epoxy resin is not particularly limited, and a prepreg can be used, for example. The styrene block copolymer or cycloolefin polymer included in the second layer 52 is the same as that in the third layer 43 .

[0045] The number of stacked first layers 51 is not particularly limited, and is, for example, 2 or more and 80 or less.

[0046] The method of fixing the second elastic member 14b to the first elastic member 14a is not particularly limited, and an example thereof includes a method of bonding the second elastic member 14b to the first elastic member 14a with an elastic adhesive.

[0047] The number of stacked corrugated leaf springs W is not limited to 4, but is preferably 2 or more and 6 or less, and more preferably 2 or more and 4 or less.

[0048] Furthermore, in the adjacent wavy leaf springs W, a portion of the concave portion R and the convex portion C that are in contact with each other may be bonded together using, for example, an elastic adhesive.

[0049] Furthermore, a corrugated leaf spring W may be used as the second elastic member 14b.

[0050] The Poisson's ratio of the first elastic member 14a is preferably 0.3 or less. If the Poisson's ratio of the first elastic member 14a is 0.3 or less, the first elastic member 14a can easily absorb the thickness changes associated with the expansion and contraction of the battery cell 11a. Alternatively, the Poisson's ratio of the first elastic member 14a is preferably 0 or greater.

[0051] The thickness of the first elastic member 14 a when the charge rate of the battery cell 11 a is 100% is not particularly limited, and is, for example, 0.05 mm or more and 0.1 mm or less.

[0052] The first elastic member 14a is, for example, a foam having a porosity of 30% to 95%. The material constituting the foam is not particularly limited, and examples thereof include polyurethane, silicone resin, ethylene propylene rubber, styrene resin, olefin resin, polyamide, and polyester.

[0053] The Young's modulus of the second elastic member 14b is preferably greater than 35 GPa. When the Young's modulus of the second elastic member 14b is greater than 35 GPa, the second elastic member 14b can easily absorb changes in thickness associated with expansion and contraction of the battery cell 11a. Alternatively, the Young's modulus of the second elastic member 14b is, for example, less than 200 GPa.

[0054] The thickness of the second elastic member 14 b when the charge rate of the battery cell 11 a is 100% is not particularly limited, and is, for example, 1.0 mm or more and 1.2 mm or less.

[0055] The battery cells 11a are not particularly limited, and examples thereof include solid battery cells such as all-solid lithium metal battery cells and semi-solid lithium metal battery cells, and electrolyte battery cells such as lithium metal battery cells. Among them, solid battery cells are preferred.

[0056] Hereinafter, a case where the battery cell 11 a is an all-solid-state lithium metal battery cell will be described.

[0057] An all-solid-state lithium metal battery cell comprises, for example, a positive electrode current collector, a positive electrode composite material layer, a solid electrolyte layer, a lithium metal layer, and a negative electrode current collector stacked in this order.

[0058] The positive electrode current collector is not particularly limited, and an example thereof includes aluminum foil.

[0059] The positive electrode composite material layer contains a positive electrode active material, and may further contain a solid electrolyte, a conductive additive, a binder, and the like.

[0060] The positive electrode active material is not particularly limited as long as it can intercalate and deintercalate lithium ions, and examples thereof include LiCoO2, Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 )O2、Li(Ni 6 / 10 Co 2 / 10 Mn 2 / 10 )O2、Li(Ni 8 / 10 Co 1 / 10 Mn 1 / 10 )O2、Li(Ni 0.8 Co 0.15 Al 0.05 )O2、Li(Ni 1 / 6 Co 4 / 6 Mn 1 / 6)O2、Li(Ni 1 / 3 Co 1 / 3 Mn 1 / 3 )O2, LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide, sulfur.

[0061] The solid electrolyte constituting the solid electrolyte layer is not particularly limited as long as it is a material capable of conducting lithium ions, and examples thereof include oxide-based electrolytes and sulfide-based electrolytes.

[0062] The negative electrode current collector is not particularly limited, and examples thereof include copper foil.

[0063] As mentioned above, although embodiment of this invention was demonstrated, this invention is not limited to the said embodiment, The said embodiment can also be modified suitably within the range of the summary of this invention.

[0064] [Example]

[0065] Hereinafter, the embodiment of the present invention will be described, but the present invention is not limited to the embodiment. In addition, in this embodiment, a leaf spring W simulating a wave shape is used (see Figure 4 ) short strip test pieces are used to evaluate the allowable strain, Young's modulus and impact reaction force.

[0066] (Example 1)

[0067] A vermilion fabric consisting of a line made of glass fiber with a fiber diameter of 7 μm as the first layer 41 and bisphenol A as the second layer 42 are made into short strip-shaped test pieces alternately stacked via Quintac styrene block copolymer (manufactured by ZEON CORPORATION, Japan) as the third layer 43. At this time, the direction of the longitudinal lines constituting the vermilion fabric is set to the length direction of the short strip. Specifically, first, bisphenol A and Quintac styrene block copolymer (manufactured by ZEON CORPORATION, Japan) are mixed in a solvent, and then the vermilion fabric is impregnated in the liquid obtained by removing the solvent to obtain a prepreg. Among them, Quintac styrene block copolymer has a block structure of polystyrene and polyisoprene. Then, after stacking the prepregs, stamping is performed to obtain a short strip-shaped test piece. At this time, the content of styrene block copolymer in the test piece is set to 10% by mass. In addition, the mass ratio of glass fiber to bisphenol A in the test piece is set to 69%.

[0068] (Comparative Example 1)

[0069] A short strip test piece was obtained in the same manner as in Example 1 except that Quintac styrene block copolymer (manufactured by Japan Zeon) was not used. The mass ratio of glass fiber to bisphenol A in the test piece was set to 69%.

[0070] [Allowable strain]

[0071] According to Japanese JIS K7161, a tensile test was performed to measure the allowable strain of the test piece.

[0072] [Young's modulus]

[0073] A three-point bending test was performed in accordance with JIS K7161 to measure the Young's modulus of the test piece. The direction of pressure applied in the three-point bending test was perpendicular to the directions of the longitudinal and transverse lines.

[0074] Figure 6 ] The relationship between the Young's modulus and the allowable strain of the test specimens of Example 1 and Comparative Example 1 is shown in FIG.

[0075] from Figure 6 It can be seen that the Young's modulus of the test piece of Example 1 is almost lower than that of the test piece of Comparative Example 1, but the allowable strain is higher. As a result, when the cushioning material 14 is compressed, it is difficult to break between the first layer 41 and the second layer 42 constituting the corrugated leaf spring W.

[0076] [Impact reaction force]

[0077] An impact test was conducted in accordance with JIS K7124-1, and the impact reaction force of the test piece was measured, wherein the impact reaction force of Comparative Example 1 was normalized to 100.

[0078] Figure 7 This is a graph showing the measurement results of the impact reaction force of the test pieces of Example 1 and Comparative Example 1.

[0079] from Figure 7 It can be seen that the test piece of Example 1 has a smaller impact reaction force and a greater impact absorption force than the test piece of Comparative Example 1. As a result, when the cushioning material 14 is compressed, the first layer 41 and the second layer 42 constituting the corrugated leaf spring W are less likely to break.

[0080] Reference numerals

[0081] 10: Battery module

[0082] 11: Battery cell stack

[0083] 11a: Battery cell

[0084] 12: End plate

[0085] 13: Binding rod

[0086] 14: Buffer material

[0087] 14a: First elastic component

[0088] 14b: Second elastic member

[0089] 41, 51: First layer

[0090] 42, 52: Second layer

[0091] 43: Third floor

[0092] W: corrugated leaf spring

[0093] R: concave part

[0094] C: convex part

Claims

1. A battery module comprising: A battery cell stack having a plurality of battery cells stacked thereon; a pair of plate-like members provided at both ends of the battery cell stack in the stacking direction; and a buffer material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped member; and The buffer material includes a corrugated leaf spring, wherein the concave portions and convex portions of the corrugated leaf spring are alternately and continuously arranged and extend in a predetermined direction. The corrugated leaf spring has a laminated structure in which layers containing glass fiber and layers containing epoxy resin are alternately laminated in the thickness direction, or a laminated structure in which layers containing glass fiber and / or epoxy resin are laminated in the thickness direction, and a layer containing a styrene block copolymer or a cycloolefin polymer is present between the laminated layers.

2. The battery module according to claim 1, wherein: In the buffer material, the corrugated leaf springs are stacked in a plurality of layers in the stacking direction of the battery cell stack, and the concave portions and the convex portions of adjacent corrugated leaf springs are in facing contact.

3. The battery module according to claim 1 or 2, wherein: The aforementioned battery cells are solid battery cells.

4. A corrugated leaf spring having concave and convex portions arranged alternately and continuously and extending in a predetermined direction. The corrugated leaf spring has a laminated structure in which layers containing glass fiber and layers containing epoxy resin are alternately laminated in the thickness direction, or a laminated structure in which layers containing glass fiber and / or epoxy resin are laminated in the thickness direction, and a layer containing a styrene block copolymer or a cycloolefin polymer is present between the laminated layers.

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