Battery module and wave-shaped plate spring

Abstract

To provide a battery module capable of increasing uniformity and strength of a surface pressure of a cushion material.SOLUTION: A battery module includes: a battery cell stacked body in which a plurality of battery cells are stacked; a pair of end plates provided at both ends of the battery cell stacked body in a stacking direction; and a cushion member disposed between the plurality of battery cells and between the battery cell stacked body and the end plates. The cushion member includes a wave-shaped plate spring W in which concave parts and convex parts are alternately arranged continuously and which extends in a predetermined direction. The wave-shaped plate spring W has a laminated structure in which a first layer 41 including glass fibers and a second layer 42 including an epoxy resin are alternately laminated in a thickness direction, and a third layer 43 including a styrene block copolymer or a cycloolefin polymer is present between the laminated first layer 41 and the second layer 42.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a battery module and a corrugated leaf spring. [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 many people have access to affordable, reliable, sustainable and advanced energy.

[0003] The battery module includes, for example, a battery cell stack in which a plurality of battery cells are stacked. Here, since the battery cells expand and contract as they are charged and discharged, the battery module includes, for example, a pair of end plates provided at both ends of the battery cell stack in the stacking direction, and a bind bar that restrains the battery cell stack between the pair of end plates.

[0004] Patent Document 1 describes an energy storage device including an energy storage module including a plurality of energy storage cells stacked in a stacking direction, a housing case that houses the energy storage module, and a limiting unit arranged between the energy storage cells. Here, the limiting unit includes a first flat plate and a second flat plate spaced apart in the stacking direction, and a corrugated plate arranged between the first flat plate and the second flat plate. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-156427 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the energy storage device described in Cited Document 1, when the limiting unit is compressed as the energy storage cells expand during charging, the difference in surface pressure between the portions of the first and second flat plates that are in contact with the corrugated plates and the portions of the first and second flat plates that are not in contact with the corrugated plates becomes large, resulting in a decrease in the uniformity of the surface pressure of the limiting unit.

[0007] Furthermore, if a corrugated plate made of glass fiber reinforced epoxy resin is applied to the energy storage device described in Reference 1, when the limiting unit is compressed as the energy storage cells expand during charging, the strength of the limiting unit will be reduced because breakage will occur between the glass fiber that makes up the corrugated plate and the epoxy resin, or the epoxy resin itself will break.

[0008] An object of the present invention is to provide a battery module that can increase the uniformity of the surface pressure and strength of the cushioning material. [Means for solving the problem]

[0009] (1) A battery module comprising: a battery cell stack in which a plurality of battery cells are stacked; a pair of plate-shaped members provided at both ends of the battery cell stack in the stacking direction; and a cushioning material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped members, wherein the cushioning material has a series of alternating concave and convex portions and a corrugated leaf spring extending in a predetermined direction, the corrugated leaf spring having a layered structure in which layers containing glass fiber and layers containing epoxy resin are alternately stacked in the thickness direction, or a layered structure in which layers containing glass fiber and / or epoxy resin are stacked in the thickness direction, and a layer containing a styrene block copolymer or a cycloolefin polymer is present between the stacked layers.

[0010] (2) The battery module described in (1), wherein the cushioning material is formed by stacking multiple layers of the corrugated leaf springs in the stacking direction of the battery cell stack, and the recesses and protrusions of adjacent corrugated leaf springs are in opposing contact with each other.

[0011] (3) The battery module according to (1) or (2), wherein the battery cells are solid-state battery cells.

[0012] (4) A corrugated leaf spring having alternatingly arranged concave and convex portions 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 the thickness direction, or a laminated structure in which layers containing glass fiber and / or epoxy resin are laminated in the thickness direction, with a layer containing a styrene block copolymer or a cycloolefin polymer present between the laminated layers. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a battery module that can increase the uniformity of the surface pressure and the strength of the cushioning material. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing a battery module according to an embodiment of the present invention. [Figure 2] FIG. 2 is a partially enlarged view of the battery module of FIG. [Figure 3] FIG. 3 is an enlarged view of the wavy leaf spring of FIG. 2. [Figure 4] FIG. 4 is a partial enlarged view of the wavy leaf spring of FIG. 3. [Figure 5] FIG. 4 is a partially enlarged view of a modified example of the wavy leaf spring of FIG. 3. [Figure 6] 1 is a graph showing the relationship between the Young's modulus and the allowable strain of the test pieces of Example 1 and Comparative Example 1. [Figure 7] 1 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 OF THE INVENTION

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

[0016] FIG. 1 shows a battery module according to one embodiment of the present invention.

[0017] The battery module 10 includes a battery cell stack 11 in which a plurality of battery cells 11a are stacked, end plates 12 as a pair of plate-like members provided at both ends of the battery cell stack 11 in the stacking direction, and bind bars 13 as restraining members that restrain the battery cell stack 11 between the pair of end plates 12. Here, the bind bars 13 are installed in two places, at the top and bottom in the drawing.

[0018] In the battery module 10, cushioning materials 14 are arranged between the plurality of battery cells 11a and between the battery cell stack 11 and the end plate 12.

[0019] The cushioning 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.

[0020] 2, the cushion 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. 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 the hysteresis loss of the cushion material 14.

[0021] Here, when the cushion material 14 is compressed due to the expansion of the battery cell 11a during charging, the first elastic member 14a is interposed between the battery cell 11a and the second elastic member 14b, so the difference in surface pressure between the portion of the first elastic member 14a that is in contact with the second elastic member 14b and the portion of the first elastic member 14a that is not in contact with the second elastic member 14b is reduced, and the uniformity of the surface pressure is increased.

[0022] 3, the corrugated leaf springs W have concave portions R and convex portions C arranged alternately and continuously, and extend in the depth direction in the figure. In addition, the second elastic member 14b has concave portions R and convex portions C of adjacent corrugated leaf springs W that face each other and are in contact with each other. The concave portions R and convex portions C are convex toward the lower and upper sides, respectively, in the stacking direction of the battery cell stack 11.

[0023] As shown in FIG. 4, the corrugated leaf spring W has a laminated structure in which first layers 41 containing glass fiber and second layers 42 containing epoxy resin are alternately stacked in the thickness direction. Between the first and second layers 41 and 42, a third layer 43 containing a styrene block copolymer or a cycloolefin polymer is present. Because the styrene block copolymer or the cycloolefin polymer has high adhesiveness and flexibility to the glass fiber and the epoxy resin, when the cushioning material 14 is compressed due to expansion of the battery cell 11a during charging, the first and second layers 41 and 42 constituting the corrugated leaf spring W are less likely to break. Furthermore, the second layer 42 is less likely to break, thereby increasing the strength of the cushioning material 14. The corrugated leaf spring W is manufactured, for example, by press molding.

[0024] The first layer 41 containing glass fiber is not particularly limited, but may be, for example, a woven fabric made of glass fiber yarn. The glass fiber may be surface-treated with a silane coupling agent, which further increases the strength of the cushioning material 14.

[0025] The epoxy resin contained in the second layer 42 is not particularly limited, but may be bisphenol A, for example.

[0026] 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% or more and 80% or less.

[0027] The styrene block copolymer contained in the third layer 43 is not particularly limited, but 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 these, copolymers having a block structure of polystyrene and polyisoprene are preferred.

[0028] The cycloolefin polymer contained in the third layer 43 may be either a homopolymer or a copolymer, and is not particularly limited.

[0029] The content of the styrene block copolymer or 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.

[0030] The wavy leaf spring W can be obtained, for example, by mixing bisphenol A and a styrene block copolymer or a cycloolefin polymer in a solvent, removing the solvent, and then impregnating a woven fabric made of glass fiber yarn with the resulting liquid, laminating the resulting prepreg, and then press-molding the resulting prepreg.

[0031] Here, the number of layers in the first layer 41 is not particularly limited, but is, for example, 2 or more and 80 or less.

[0032] As shown in FIG. 5, 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, and second layers 52 containing styrene block copolymer or cycloolefin polymer may be present between the laminated first layers 51.

[0033] The first layer 51 containing glass fiber and epoxy resin is not particularly limited, but may be made of, for example, prepreg. The styrene block copolymer or cycloolefin polymer contained in the second layer 52 is the same as that contained in the third layer 43.

[0034] Here, the number of layers in the first layer 51 is not particularly limited, but is, for example, 2 or more and 80 or less.

[0035] The method for fixing the second elastic member 14b to the first elastic member 14a is not particularly limited, but may be, for example, a method for bonding the second elastic member 14b to the first elastic member 14a with an elastic adhesive.

[0036] The number of layers of the corrugated leaf spring W is not limited to four, but is preferably two or more and six or less, and more preferably two or more and four or less.

[0037] Furthermore, adjacent corrugated leaf springs W may have portions of the recessed portions R and protruding portions C that are in contact with each other and face each other bonded together by, for example, an elastic adhesive.

[0038] Furthermore, a wave-shaped leaf spring W may be used as the second elastic member 14b.

[0039] The Poisson's ratio of the first elastic member 14a is preferably 0.3 or less. When the Poisson's ratio of the first elastic member 14a is 0.3 or less, the first elastic member 14a can easily absorb the change in thickness caused by the expansion and contraction of the battery cell 11a. The Poisson's ratio of the first elastic member 14a is, for example, 0 or more.

[0040] The thickness of the first elastic member 14a when the charging rate of the battery cell 11a is 100% is not particularly limited, but is, for example, 0.05 mm or more and 0.1 mm or less.

[0041] The first elastic member 14a is, for example, a foam having a porosity of 30% or more and 95% or less. The material constituting the foam is not particularly limited, but examples thereof include polyurethane, silicone resin, ethylene propylene rubber, styrene resin, olefin resin, polyamide, and polyester.

[0042] The Young's modulus of the second elastic member 14b is preferably 35 GPa or more. If the Young's modulus of the second elastic member 14b is 35 GPa or more, the second elastic member 14b can easily absorb the change in thickness caused by the expansion and contraction of the battery cell 11a. The Young's modulus of the second elastic member 14b is, for example, 200 GPa or less.

[0043] The thickness of the second elastic member 14b when the charging rate of the battery cell 11a is 100% is not particularly limited, but is, for example, not less than 1.0 mm and not more than 1.2 mm.

[0044] The battery cell 11a is not particularly limited, but 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 these, solid battery cells are preferred.

[0045] The following describes the case where the battery cell 11a is an all-solid-state lithium metal battery cell.

[0046] An all-solid-state lithium metal battery cell includes, for example, a positive electrode current collector, a positive electrode mixture layer, a solid electrolyte layer, a lithium metal layer, and a negative electrode current collector stacked in this order.

[0047] The positive electrode current collector is not particularly limited, but may be, for example, aluminum foil.

[0048] The positive electrode mixture layer contains a positive electrode active material, and may further contain a solid electrolyte, a conductive additive, a binder, and the like.

[0049] The positive electrode active material is not particularly limited as long as it can absorb and release lithium ions. For example, LiCoO2, Li(Ni 5 / 10 Co 2 / 10 Mn 3 / 10 )O 2、 Li(Ni) 6 / 10 Co 2 / 10 Mn 2 / 10 )O 2、 Li(Ni) 8 / 10 Co 1 / 10 Mn1 / 10 )O 2、 Li(Ni) 0.8 Co 0.15 Al 0.05 )O 2、 Li(Ni) 1 / 6 Co 4 / 6 Mn 1 / 6 )O 2、 Li(Ni) 1 / 3 Co 1 / 3 Mn 1 / 3 )O 2、 Examples include LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide, and sulfur.

[0050] 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.

[0051] The negative electrode current collector is not particularly limited, but may be, for example, copper foil.

[0052] Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and the above-described embodiments may be modified as appropriate within the scope of the spirit of the present invention. [Example]

[0053] Examples of the present invention will be described below, but the present invention is not limited to these examples. In these examples, the allowable strain, Young's modulus, and impact reaction force were evaluated using rectangular test pieces simulating a corrugated leaf spring W (see FIG. 4).

[0054] [Example 1] A rectangular test specimen was prepared by alternately laminating a first layer 41 (a satin weave fabric composed of glass fiber yarns with a fiber diameter of 7 μm) and a second layer 42 (bisphenol A) with a third layer 43 (Quintac styrene block copolymer (manufactured by Zeon Corporation)) in between. The direction of the warp yarns constituting the satin weave was the longitudinal direction of the test specimen. Specifically, bisphenol A and Quintac styrene block copolymer (manufactured by Zeon Corporation) were first mixed in a solvent, and the solvent was then removed. The resulting liquid was then impregnated with the satin weave to obtain a prepreg. The Quintac styrene block copolymer has a block structure of polystyrene and polyisoprene. The prepregs were then laminated and press-molded to obtain a rectangular test specimen. The styrene block copolymer content in the test specimen was 10% by mass. The mass ratio of glass fiber to bisphenol A in the test specimen was 69%.

[0055] [Comparative Example 1] Except for not using Quintac styrene block copolymer (manufactured by Zeon Corporation), a strip-shaped test piece was obtained in the same manner as in Example 1. At this time, the mass ratio of glass fiber to bisphenol A in the test piece was set to 69%.

[0056] [Allowable distortion] A tensile test was carried out in accordance with JIS K7161 to measure the allowable strain of the test specimen.

[0057] Young's Modulus A three-point bending test was carried out in accordance with JIS K7171 to measure the Young's modulus of the test piece. At this time, the pressure direction in the three-point bending test was set to a direction perpendicular to the direction of the warp and weft yarns that constitute the test piece.

[0058] 6 shows the relationship between the Young's modulus and the allowable strain of the test pieces of Example 1 and Comparative Example 1. Here, the allowable strain and Young's modulus of Comparative Example 1 are normalized to 100.

[0059] 6, it can be seen that the Young's modulus of the test piece of Example 1 is almost the same as that of the test piece of Comparative Example 1, and the allowable strain is increased. 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.

[0060] [Impact Reaction Force] An impact test was carried out in accordance with JIS K7124-1 to measure the impact reaction force of the test piece. Here, the impact reaction force of Comparative Example 1 was normalized to 100.

[0061] FIG. 7 is a graph showing the measurement results of the impact reaction force of the test pieces of Example 1 and Comparative Example 1.

[0062] 7, it can be seen that the test piece of Example 1 has a reduced impact reaction force and an increased impact absorption capacity compared to the test piece of Comparative Example 1. As a result, when the cushioning material 14 is compressed, it is less likely to break between the first layer 41 and the second layer 42 that make up the corrugated leaf spring W. [Explanation of symbols]

[0063] 10 Battery Module 11 Battery cell stack 11a battery cell 12 End plate 13 Binding Bar 14 Cushioning material 14a First elastic member 14b Second elastic member 41, 51 1st layer 42, 52 2nd layer 43 3rd layer W wavy leaf spring R recess C Convex part

Claims

1. a battery cell stack in which a plurality of battery cells are stacked; a pair of plate-shaped members provided at both ends of the battery cell stack in a stacking direction; a cushioning material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped member, The cushioning material has concave and convex portions alternately arranged in succession and includes a wave-shaped leaf spring extending in a predetermined direction; The wavy 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. 2. The battery module according to claim 1, wherein the cushioning material includes a plurality of layers of the corrugated leaf springs stacked in a stacking direction of the battery cell stack, and the recesses and protrusions of adjacent corrugated leaf springs are in opposing contact with each other.

3. The battery module according to claim 1 or 2, wherein the battery cells are solid-state battery cells.

4. A wave-shaped leaf spring in which recesses and protrusions are alternately and continuously arranged and which extends in a predetermined direction, A 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.

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