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-form members that are provided at the two stacking-direction ends of the battery cell stack, and a cushion material that is disposed between the plurality of battery cells and / or between the battery cell stack and the plate-form members. The cushion material is provided with a pair of first elastic members that are disposed on the two stacking-direction outer sides of the battery cell stack, and a second elastic member that is disposed between the pair of first elastic members. In the second elastic member, a plurality of wave-shaped leaf springs are stacked 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. One or both of the pair of first elastic members have an extension part that extends toward the other of the pair of first elastic members, the extension part being provided further toward one or both width-direction outer sides than the second elastic member.

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 due to expansion of the energy storage cells 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 due to expansion of the energy storage cells during charging, the widthwise ends of the corrugated plate come into contact with members located to the sides of the corrugated plate in the widthwise direction, which may damage the energy storage device.

[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.

[0008] (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 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 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 formed by stacking multiple layers of corrugated leaf springs in the stacking direction of the battery cell stack, and wherein there are multiple contact areas in the width direction that are in contact with the first elastic members, and one or both of the pair of first elastic members have an extension portion that extends toward the other of the pair of first elastic members, on one or both outer sides of the second elastic member in the width direction.

[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 widthwise length between the top surface of the convex portion or the bottom surface of the concave portion adjacent to the widthwise end and the widthwise end of the wavy leaf spring 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 ends of the corrugated leaf spring in the width direction are not fixed.

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

[0014] (7) A battery module described in any one of (1) to (6), wherein the cushion material has an extension portion that is in contact with the other of the pair of first elastic members.

[0015] (8) The battery module according to (7), wherein the cushion material has the extension portion fixed to the other of the pair of first elastic members.

[0016] (9) The battery module according to (7), wherein the cushioning material is formed by integrating the pair of first elastic members.

[0017] (10) The battery module according to any one of (1) to (9), wherein the battery cells are solid-state battery cells.

[0018] (11) A method for manufacturing a battery module described in (4), wherein the cushion material is formed by integrating the pair of first elastic members, and the method includes a step of applying elastic adhesive to both surfaces of the second elastic member, and a step of inserting the second elastic member to which the elastic adhesive has been applied into the pair of integrated first elastic members.

[0019] (12) 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.

[0020] 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.

[0021] Fig. 1 is a cross-sectional view showing a battery module according to an embodiment of the present invention. Fig. 2 is a cross-sectional view showing a cushion material of Fig. 1. Fig. 3 is a partially enlarged cross-sectional view of the cushion material of Fig. 2. Fig. 4 is a cross-sectional view showing a corrugated leaf spring of Fig. 2. Fig. 5 is a cross-sectional view illustrating a method for manufacturing the cushion material of Fig. 2. Fig. 6 is a cross-sectional view illustrating a modified example of the method for manufacturing the cushion material of Fig. 2.

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0023] FIG. 1 shows a battery module according to one embodiment of the present invention.

[0024] 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.

[0025] 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 .

[0026] 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 .

[0027] 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 and 14c. 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 hysteresis loss of the cushion material 14.

[0028] Here, when the cushion material 14 is compressed due to the expansion of the battery cell 11a during charging, the first elastic members 14a and 14c are interposed between the battery cell 11a and the second elastic member 14b, so the difference in surface pressure between the portions of the first elastic members 14a and 14c that are in contact with the second elastic member 14b and the portions of the first elastic members 14a and 14c that are not in contact with the second elastic member 14b is reduced, and the uniformity of the surface pressure is increased.

[0029] The second elastic member 14b has a plurality of contact areas A in the width direction D where it is in contact with the first elastic members 14a and 14c. The first elastic member 14a has an extension E extending toward the first elastic member 14c on one side of the width direction D outside the second elastic member 14b, and the extension E is in contact with the first elastic member 14c (see FIG. 3 ). The first elastic member 14c also has an extension E extending toward the first elastic member 14a on the other side of the width direction D outside the second elastic member 14b, and the extension E is in contact with the first elastic member 14a. Therefore, when the cushion material 14 is compressed due to the expansion of the battery cell 11a during charging, contact between the second elastic member 14b and components located to the sides of the second elastic member 14b in the width direction D is suppressed, thereby suppressing damage to the battery module 10.

[0030] In addition, the cushion material 14 may have an extension portion in the first elastic member 14a and an extension portion in the first elastic member 14c. In this case, the first elastic member 14a may have an extension portion extending toward the first elastic member 14c on both outer sides of the second elastic member 14b in the width direction D.

[0031] Furthermore, the extending portion of the cushion material 14 does not need to be in contact with the first elastic member 14c (or 14a).

[0032] 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. The recesses R and protrusions C of adjacent corrugated leaf springs W face each other and are in contact with each other. The recesses R and protrusions C are convex toward the bottom and top of the stacking direction of the battery cell stack 11, respectively. The length L1 in the width direction D between the end of the corrugated leaf spring W in the width direction D and the top surface of the protrusion C (or the bottom surface of the recess R) adjacent to the end of the corrugated leaf spring W in the width direction D is greater than the length L2 in the width direction D 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.

[0033] In the cushion material 14, the first elastic members 14a and 14c and the second elastic member 14b are fixed to each other 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 members 14a and 14c and the second elastic member 14b to each other at the contact area A, but examples of the method include using an elastic adhesive to bond the first elastic members 14a and 14c and the second elastic member 14b to each other at the contact area A.

[0034] In the cushion material 14, the extension portion E of the first elastic member 14a is fixed to the first elastic member 14c, and the extension portion of the first elastic member 14c is fixed to the first elastic member 14a, thereby improving the strength of the cushion material 14. There are no particular limitations on the method for fixing the extension portion to the first elastic member, but one example is a method of bonding the extension portion to the first elastic member with an elastic adhesive.

[0035] The first elastic members 14a and 14c may be integrated into the cushion material 14. That is, the cushion material 14 may include an elastic member having a shape in which the first elastic members 14a and 14c are integrated.

[0036] On the other hand, the ends of the corrugated leaf springs W in the width direction D are not fixed. Furthermore, the ends of the corrugated leaf springs W in the width direction D are spaced apart from adjacent corrugated leaf springs W. This reduces hysteresis loss of the second elastic member 14b. The distance 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.

[0037] The number of layers of the wavy leaf spring W is not limited to 2, but may be 2 or more. The number of layers of the wavy leaf spring W is not particularly limited, but may be, for example, 2 to 6. When the number of layers of the wavy leaf spring W is 3 or more, the shape of the wavy leaf spring W that is not in contact at the contact area A is not particularly limited, but may be, for example, the same as the shape of the wavy leaf spring W that is in contact at the contact area A.

[0038] 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.

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

[0040] The thickness of the first elastic members 14a and 14c 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.

[0041] The first elastic members 14 a and 14 c are, for example, foams having a porosity of 30% to 95%. The material for the foams 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. 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.

[0043] 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.

[0044] 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.

[0045] 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 14c is placed on it (see FIG. 5(a)). Pressure may be applied simultaneously with or after placing the first elastic member 14c 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 surfaces of the upper protrusions C of the second elastic member 14b and the end surfaces of the extensions of the first elastic members 14a and 14c, 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.

[0046] Next, a modified manufacturing method of the cushioning material 14 will be described. First, a first elastic member 14d is obtained by foam molding. Here, the first elastic member 14d is formed by integrating the first elastic members 14a and 14c. Meanwhile, a corrugated leaf spring W is formed by press molding, and then a portion of the two-layered corrugated leaf spring W is bonded with an elastic adhesive to obtain the second elastic member 14b. Next, an elastic adhesive G is applied to the top surface of the upper convex portion C and the bottom surface of the lower concave portion R of the second elastic member 14b, and the second elastic member 14b is then inserted into the first elastic member 14d (see FIG. 6 ). Since the second elastic member 14b is positioned by the first elastic member 14d, misalignment is less likely to occur, resulting in improved assembly of the cushioning material 14. Pressurization may be applied simultaneously with or after inserting the second elastic member 14b into the first elastic member 14d.

[0047] The cushion material 14 manufactured in the above manner has high strength, which improves the transportability of the cushion material 14, and as a result, improves the assembly efficiency of the battery module 10.

[0048] As a method for manufacturing the battery module 10 using the cushion material 14, a known method can be used.

[0049] 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.

[0050] Hereinafter, a case where the battery cell 11a is an all-solid-state lithium metal battery cell will be described.

[0051] 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.

[0052] The positive electrode current collector is not particularly limited, but may be, for example, aluminum foil.

[0053] 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.

[0054] 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 ２O ４ , LiNiO ２ , LiFePO ４ , lithium sulfide, and sulfur.

[0055] 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.

[0056] The negative electrode current collector is not particularly limited, but may be, for example, copper foil.

[0057] 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.

[0058] REFERENCE SIGNS LIST 10 Battery module 11 Battery cell stack 11a Battery cell 12 End plate 13 Bind bar 14 Cushion material 14a, 14c, 14d 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 member is made of multiple layers of corrugated leaf springs stacked in the stacking direction of the battery cell stack, and has multiple contact areas in the width direction that are in contact with the first elastic members, and one or both of the pair of first elastic members has an extension portion that extends toward the other of the pair of first elastic members, on one or both outer sides of the second elastic member in the width direction.

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 according to claim 2, wherein the widthwise length between the end of the wavy leaf spring and the top surface of the convex portion or the bottom surface of the concave portion adjacent to the end of the widthwise direction 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 ends of the corrugated leaf spring in the width direction are not fixed.

6. The battery module according to any one of claims 1 to 3, wherein the corrugated leaf springs are spaced apart from adjacent corrugated leaf springs at the ends in the width direction.

7. The battery module according to any one of claims 1 to 3, wherein the cushion material has an extension portion that contacts the other of the pair of first elastic members.

8. The battery module according to claim 7, wherein the cushion material has the extension portion fixed to the other of the pair of first elastic members.

9. The battery module according to claim 7, wherein the cushioning material is formed by integrating the pair of first elastic members.

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

11. A method for manufacturing a battery module as described in claim 4, wherein the cushioning material is formed by integrating the pair of first elastic members, and the method includes the steps of applying elastic adhesive to both surfaces of the second elastic member, and inserting the second elastic member to which the elastic adhesive has been applied into the pair of integrated first elastic members.

12. 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.

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