Battery module and method for manufacturing battery module

Abstract

Provided is 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 cushion material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped members. The cushion material is provided with: a pair of first elastic members disposed on both outer sides of the battery cell stack in the stacking direction; and a second elastic member disposed between the pair of first elastic members. In the second elastic member, wavy leaf springs are stacked in 2N layers (where N is a natural number) in the stacking direction of the battery cell stack, and a plurality of contact regions that are in contact with the first elastic members are present in the width direction. The wavy leaf springs that are in contact with the contact regions have extension portions that extend outward in the width direction from the contact regions that are present at the outermost portions in the width direction. In the extension portions, the distances in the thickness direction from the first elastic members that are in contact with the contact regions increase as the distances in the width direction from the contact regions that are present at the outermost portions in the width direction increase.

Description

Battery module and method of manufacturing the battery module

[0001] The present invention relates to a battery module and a method for manufacturing the battery module.

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been conducted to ensure that many people have access to affordable, reliable, sustainable and advanced energy.

[0003] Since 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 Literature 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 for housing 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.

[0005] Japanese Patent Application Laid-Open No. 2022-156427

[0006] However, in the energy storage device described in Patent 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 plate and the portions of the first and second flat plates that are not in contact with the corrugated plate increases, resulting in a low uniformity of surface pressure on the limiting unit. Also, in the energy storage device described in Patent Document 1, when the limiting unit is compressed as the energy storage cells expand during charging, the widthwise ends of the corrugated plate come into contact with the energy storage cells, which may damage the energy storage cells.

[0007] An object of the present invention is to provide a battery module that can increase the uniformity of the surface pressure of a cushioning material and suppress damage to battery cells.

[0008] (1) A battery module including: 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; and cushioning material arranged between the plurality of battery cells and / or between the battery cell stack and the plate-shaped members, wherein the cushioning material includes a pair of first elastic members arranged on both outer sides of the battery cell stack in the stacking direction, and a second elastic member arranged between the pair of first elastic members, wherein the second elastic members are corrugated leaf springs stacked in 2N layers (where N is a natural number) in the stacking direction of the battery cell stack, and wherein a plurality of contact areas in a width direction are in contact with the first elastic members, and the corrugated leaf springs in contact at the contact areas have extension portions extending outward in the width direction from the outermost contact areas in the width direction, and the thickness direction distance of the extension portions from the first elastic members in contact at the contact areas increases as the width direction distance from the outermost contact areas in the width direction increases.

[0009] (2) The battery module described in (1), wherein the corrugated leaf springs have concave and convex portions arranged alternately and continuously and extend in a predetermined direction, and the second elastic member is such that the concave and convex portions of adjacent corrugated leaf springs face each other and come into contact with each other.

[0010] (3) The battery module described in (2), wherein the wavy leaf spring in contact at the contact area has a widthwise length between the end of the extension portion and the top surface of the convex portion or the bottom surface of the concave portion adjacent to the end of the extension portion that is greater than the widthwise length between the bottom surface of the adjacent concave portion and the top surface of the convex portion.

[0011] (4) A battery module described in any one of (1) to (3), wherein the cushion material fixes the pair of first elastic members and the second elastic member at the contact area.

[0012] (5) A battery module described in any one of (1) to (4), wherein the corrugated leaf springs in contact at the contact area have the extension portions not fixed.

[0013] (6) The battery module according to any one of (1) to (5), wherein the corrugated leaf springs in contact at the contact region are spaced apart from adjacent corrugated leaf springs at the extension portions.

[0014] (7) The battery module according to any one of (1) to (6), wherein the battery cells are solid-state battery cells.

[0015] (8) A method for manufacturing the battery module described in (4), comprising the steps of applying an elastic adhesive to one side of the second elastic member, placing one of the pair of first elastic members on the one side of the second elastic member on which the elastic adhesive has been applied, applying an elastic adhesive to the other side of the second elastic member, and placing the other of the pair of first elastic members on the other side of the second elastic member on which the elastic adhesive has been applied.

[0016] (9) A method for manufacturing a battery module as described in (8), further comprising the steps of: applying pressure at the same time as placing the first elastic member on one side of the second elastic member on which the elastic adhesive has been applied, or after placing the first elastic member on one side of the second elastic member on which the elastic adhesive has been applied; and applying pressure at the same time as placing the first elastic member on the other side of the second elastic member on which the elastic adhesive has been applied, or after placing the first elastic member on the other side of the second elastic member on which the elastic adhesive has been applied.

[0017] According to the present invention, it is possible to provide a battery module that can increase the uniformity of the surface pressure of the cushioning material and suppress damage to the battery cells.

[0018] It is a cross-sectional view showing a battery module according to an embodiment of the present invention. It is a cross-sectional view showing the cushion material of Figure 1. It is a partially enlarged cross-sectional view of the cushion material of Figure 2. It is a cross-sectional view showing the corrugated leaf spring of Figure 2. It is a cross-sectional view explaining a manufacturing method of the cushion material of Figure 2.

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

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

[0021] The battery module 10 includes a battery cell stack 11 in which a plurality of battery cells 11a are stacked, end plates 12 serving 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 serving 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 locations, at the top and bottom, in the drawing.

[0022] 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 plate 12 .

[0023] 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 .

[0024] 2, the cushion material 14 includes a pair of first elastic members 14a disposed on both outer sides in the stacking direction of the battery cell stack 11, and a second elastic member 14b disposed between the pair of first elastic members 14a. The second elastic member 14b is formed by stacking two 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.

[0025] 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.

[0026] The second elastic member 14b has a plurality of contact areas A in the width direction D1 where it is in contact with the first elastic member 14a. The corrugated leaf spring W in contact with the contact areas A has extension portions E that extend outward in the width direction D1 from the outermost contact areas A on both sides of the width direction D (see FIG. 3 ). The greater the distance in the width direction D1 from the outermost contact areas A in the width direction D1, the greater the distance in the thickness direction D2 of the extension portions E from the first elastic member 14a with which it is in contact at the contact areas A. Therefore, when the cushion material 14 is compressed as the battery cell 11a expands during charging, contact between the extension portions E and the battery cell 11a is suppressed, thereby suppressing damage to the battery cell 11a.

[0027] In addition, the corrugated leaf spring W in contact at the contact area A may have an extension portion E extending from the contact area A located at one outermost position in the width direction D1 toward the outside in the width direction D1.

[0028] As shown in FIG. 4 , the corrugated leaf springs W constituting the second elastic member 14b have alternating recesses R and protrusions C arranged in succession and extending in the depth direction. Adjacent corrugated leaf springs W are in contact with each other at their recesses R and protrusions C. The recesses R and protrusions C are convex toward the bottom and top of the stacking direction of the battery cell stack 11, respectively. In the corrugated leaf springs W contacting at the contact area A, the length L1 in the width direction D1 between the end of the extension E and the top surface of the protrusion C (or the bottom surface of the recess R) adjacent to the end of the extension E is greater than the length L2 in the width direction D1 between the bottom surface of the adjacent recess R and the top surface of the protrusion C. This reduces hysteresis loss of the second elastic member 14b. The ratio of L1 to L2 is not particularly limited, but is, for example, 1 to 2. L1 is also not particularly limited, but is, for example, 5 mm to 20 mm.

[0029] In the cushion material 14, the first elastic member 14a and the second elastic member 14b are fixed at the contact area A. This improves the strength of the cushion material 14. There are no particular limitations on the method for fixing the first elastic member 14a and the second elastic member 14b at the contact area A, but one example is a method in which the first elastic member 14a and the second elastic member 14b are bonded at the contact area A with an elastic adhesive.

[0030] On the other hand, the corrugated leaf springs W in contact at the contact area A have their extensions E not fixed. The corrugated leaf springs W in contact at the contact area A are separated from adjacent corrugated leaf springs W at their extensions E. This reduces hysteresis loss in the second elastic member 14b. The spacing between the ends of adjacent corrugated leaf springs W in the width direction D is not particularly limited, but is, for example, 0.1 mm to 1 mm.

[0031] The number of layers of the corrugated leaf springs W is not limited to 2, but may be 2N (where N is a natural number). N is not particularly limited, but may be, for example, 1 to 3. When N is 2 or more, the corrugated leaf springs W that are not in contact at the contact area A have extensions corresponding to the extensions E of the corrugated leaf springs W that are in contact at the contact area A.

[0032] In addition, 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.

[0033] 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 changes 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.

[0034] 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, not less than 0.05 mm and not more than 0.1 mm.

[0035] 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, but examples thereof include polyurethane, silicone resin, ethylene propylene rubber, styrene resin, olefin resin, polyamide, and polyester.

[0036] The Young's modulus of the second elastic member 14b is preferably 35 GPa or more. When 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.

[0037] The material constituting the second elastic member 14b is not particularly limited, but examples thereof include metals such as stainless steel and carbon steel, resins such as epoxy resin, phenolic resin, and nylon resin, and fiber reinforced plastics (FRP) such as carbon fiber reinforced plastic (CFRP) and glass fiber reinforced plastic (GFRP). Among these, FRP is preferable in consideration of the energy density of the battery module 10.

[0038] 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.

[0039] An example of a manufacturing method for the cushioning material 14 is described below. First, a first elastic member 14a is obtained by foam molding. Then, a corrugated leaf spring W is formed by press molding, and a portion of the two-layered corrugated leaf spring W is bonded with an elastic adhesive to obtain a second elastic member 14b. Next, an elastic adhesive G is applied to the bottom surface of the lower recess R of the second elastic member 14b, and then the first elastic member 14a is placed on it (see FIG. 5(a)). At this time, pressure may be applied simultaneously with or after placing the first elastic member 14a on the bottom surface of the lower recess R of the second elastic member 14b. Next, an elastic adhesive G is applied to the top surface of the upper protrusion C of the second elastic member 14b, and then the first elastic member 14a is placed on it (see FIG. 5(b)). At this time, pressure may be applied at the same time as placing the first elastic member 14a on the top surface of the upper convex portion C of the second elastic member 14b, or after placing the first elastic member 14a on the top surface of the upper convex portion C of the second elastic member 14b.

[0040] As a method for manufacturing the battery module 10 using the cushion material 14, a known method can be used.

[0041] The battery cell 11a is not particularly limited, but examples thereof include solid-state battery cells such as all-solid-state lithium metal battery cells, and electrolyte battery cells such as lithium metal battery cells. Among these, solid-state battery cells are preferred.

[0042] Hereinafter, a case where the battery cell 11a is an all-solid-state lithium metal battery cell will be described.

[0043] 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.

[0044] The positive electrode current collector is not particularly limited, but may be, for example, aluminum foil.

[0045] 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.

[0046] The positive electrode active material is not particularly limited as long as it can absorb and release lithium ions. For example, LiCoO ２ , 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 Mn １／１０ ) 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、 LiCoO ４ , LiMn ２ O ４ , LiNiO ２ , LiFePO ４ , lithium sulfide, and sulfur.

[0047] 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.

[0048] The negative electrode current collector is not particularly limited, but may be, for example, copper foil.

[0049] 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.

[0050] REFERENCE SIGNS LIST 10 Battery module 11 Battery cell stack 11a Battery cell 12 End plate 13 Bind bar 14 Cushion material 14a First elastic member 14b Second elastic member A Contact area E Extension portion W Wave-shaped leaf spring R Recess C Protrusion G Elastic adhesive

Claims

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 cushioning material arranged between the plurality of battery cells and / or between the battery cell stack and the plate-shaped members, wherein the cushioning material comprises a pair of first elastic members arranged on both outer sides of the battery cell stack in the stacking direction, and a second elastic member arranged between the pair of first elastic members, wherein the second elastic members are corrugated leaf springs stacked in 2N layers (where N is a natural number) in the stacking direction of the battery cell stack, and wherein there are a plurality of contact areas in the width direction that are in contact with the first elastic members, and the corrugated leaf springs in contact at the contact areas have extension portions that extend outward in the width direction from the outermost contact area in the width direction, and wherein the thickness direction distance of the extension portions from the first elastic members in contact at the contact areas increases as the width direction distance from the outermost contact area in the width direction increases.

2. The battery module according to claim 1, wherein the corrugated leaf springs have concave and convex portions alternately arranged in succession and extending in a predetermined direction, and the second elastic member is configured such that the concave and convex portions of adjacent corrugated leaf springs face each other and come into contact with each other.

3. The battery module of claim 2, wherein the wavy leaf spring in contact at the contact region has a widthwise length between the end of the extension portion and the top surface of the convex portion or the bottom surface of the concave portion adjacent to the end of the extension portion that is greater than the widthwise length between the bottom surface of the adjacent concave portion and the top surface of the convex portion.

4. The battery module according to any one of claims 1 to 3, wherein the cushion material fixes the pair of first elastic members and the pair of second elastic members at the contact area.

5. The battery module according to any one of claims 1 to 3, wherein the corrugated leaf springs in contact at the contact region have the extensions not fixed.

6. The battery module according to any one of claims 1 to 3, wherein the corrugated leaf springs in contact at the contact region are spaced apart from adjacent corrugated leaf springs at the extension portions.

7. The battery module according to any one of claims 1 to 3, wherein the battery cells are solid-state battery cells.

8. A method for manufacturing a battery module as described in claim 4, comprising the steps of: applying an elastic adhesive to one surface of the second elastic member; placing one of the pair of first elastic members on the one surface of the second elastic member on which the elastic adhesive has been applied; applying an elastic adhesive to the other surface of the second elastic member; and placing the other of the pair of first elastic members on the other surface of the second elastic member on which the elastic adhesive has been applied.

9. A method for manufacturing a battery module as described in claim 8, further comprising the steps of: applying pressure at the same time as placing the first elastic member on one side of the second elastic member on which the elastic adhesive has been applied, or after placing the first elastic member on one side of the second elastic member on which the elastic adhesive has been applied; and applying pressure at the same time as placing the first elastic member on the other side of the second elastic member on which the elastic adhesive has been applied, or after placing the first elastic member on the other side of the second elastic member on which the elastic adhesive has been applied.

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