Battery Module

Abstract

To provide a battery module which enables the energy density thereof to be increased and has cushion material and enables the uniformity of surface pressure of the cushion material to be increased.SOLUTION: A battery module 10 comprises: a battery cell laminate 11 in which a plurality of battery cells 11a are laminated; a pair of end plates 12 provided at both ends in a laminating direction, of the battery cell laminate 11; and cushion material 14 which is disposed between the plurality of battery cells 11a and between the battery cell laminate 11 and the end plate 12. The cushion material 14 has: a pair of first elastic members disposed on both outsides in the laminating direction, of the battery cell laminate 11; a second elastic member disposed between the pair of first elastic members; and a rigid member disposed between the first elastic member and the second elastic member.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a battery module. [Background technology]

[0002] In recent years, research and development into secondary batteries that contribute to energy efficiency has been carried out 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 in the stacking direction of the battery cell stack, and a bind bar that restrains the battery cell stack between the pair of end plates.

[0004] However, all-solid-state battery cells undergo large volume changes due to expansion and contraction during charging and discharging, which changes the dimensions of the battery module, making it difficult to mount the battery module on a vehicle.

[0005] Patent Document 1 describes a battery pack in which gap adjustment units are intermittently disposed between all-solid-state battery cells. Here, the gap adjustment unit has an elastic body disposed between a pair of plates. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2020-77500 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, there is room for improvement in the energy density of battery modules.

[0008] For example, in order to further absorb the expansion and contraction that occurs when the all-solid-state battery cell is charged and discharged, it is conceivable to use a cushioning material in which a second elastic member is disposed between a pair of first elastic members.

[0009] However, when the cushioning material is compressed due to expansion of the all-solid-state battery cell during charging, the difference in surface pressure between the portion of the first elastic member that is in contact with the second elastic member and the portion of the first elastic member that is not in contact with the second elastic member may become large, which may reduce the uniformity of the surface pressure of the cushioning material.

[0010] An object of the present invention is to provide a battery module that can increase the energy density and the uniformity of the surface pressure of a cushioning material. [Means for solving the problem]

[0011] (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 a 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 has a pair of first elastic members arranged on both outer sides of the battery cell stack in the stacking direction, a second elastic member arranged between the pair of first elastic members, and a rigid member arranged between the first elastic member and the second elastic member.

[0012] (2) The battery module described in (1), wherein the second elastic member has a recess or a through hole.

[0013] (3) The battery module according to (2), wherein the recess or through hole has a diameter of 4 mm or less.

[0014] (4) The battery module according to any one of (1) to (3), wherein the rigid member has a Poisson's ratio of 0.3 or less.

[0015] (5) The battery module described in (4), wherein the rigid member includes stainless steel.

[0016] (6) The battery module according to any one of (1) to (5), wherein the battery cells are solid-state battery cells. Effect of the Invention

[0017] According to the present invention, it is possible to provide a battery module that can increase the energy density and the uniformity of the surface pressure of the cushioning material. [Brief description of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view showing an example of a battery module of the present embodiment. [Diagram 2] FIG. 2 is a partially exploded perspective view showing the cushioning material of FIG. [Diagram 3] 11 is a cross-sectional view showing a state in which the cushioning material is compressed when no rigid member is disposed between the foam body and the honeycomb structure. FIG. [Figure 4] 3 is a side view showing a modified example of the cushioning material in FIG. 2. [Diagram 5] 3 is a side view showing a modified example of the cushioning material in FIG. 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

[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 in the stacking direction of the battery cell stack 11, 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 provided in two locations, the upper and lower parts in the drawing.

[0022] In the battery module 10, cushioning materials 14 are disposed between the multiple battery cells 11a and between the battery cell stack 11 and the end plates 12.

[0023] The cushioning material 14 may be disposed between the multiple battery cells 11a or between the battery cell stack 11 and the end plate 12.

[0024] As shown in FIG. 2, the cushioning material 14 has a pair of foam bodies 14a as first elastic members arranged on both outer sides in the stacking direction of the battery cell stack 11, a honeycomb structure 14b as a second elastic member arranged between the pair of foam bodies 14a, and a rigid member 14c arranged between the foam bodies 14a and the honeycomb structure 14b.

[0025] Here, when the cushioning material 14 is compressed due to the expansion of the battery cell 11a during charging, the rigid member 14c is disposed between the foam 14a and the honeycomb structure 14b, so that the difference in surface pressure between the portion of the foam 14a in contact with the honeycomb structure 14b and the portion of the foam 14a not in contact with the honeycomb structure 14b is reduced, and the uniformity of the surface pressure is increased.

[0026] In contrast, if the rigid member 14c is not disposed between the foam 14a and the honeycomb structure 14b, when the cushioning material is compressed, only the portion of the foam 14a in contact with the honeycomb structure 14b may be compressed (see FIG. 3). As a result, the difference in surface pressure between the portion of the foam 14a in contact with the honeycomb structure 14b and the portion of the foam 14a not in contact with the honeycomb structure 14b increases, and the surface pressure becomes less uniform. This tendency becomes more pronounced when the thickness of the foam 14a is small, i.e., when the energy density of the battery module 10 is high.

[0028] The Poisson's ratio of the first elastic member is preferably 0.3 or less. When the Poisson's ratio of the first elastic member is 0.3 or less, the first elastic member is more likely to 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 is not particularly limited, but is, for example, 0 or more.

[0029] The spring constant per unit area of ​​the second elastic member is preferably 0.9 MPa / mm or more. When the spring constant per unit area of ​​the second elastic member is 0.9 MPa / mm or more, the energy density of the battery module 10 increases. The spring constant per unit area of ​​the second elastic member is not particularly limited, but is, for example, 2.0 MPa / mm or less.

[0030] The porosity of the foam 14a is not particularly limited, but is, for example, not less than 30% and not more than 95%.

[0031] The thickness of the foam 14a at SOC 100% is not particularly limited, but is, for example, not less than 0.07 mm and not more than 0.5 mm.

[0032] The material constituting the foam 14a is not particularly limited, but examples thereof include polyurethane, silicone resin, ethylene propylene rubber, styrene resin, olefin resin, polyamide, and polyester.

[0033] The porosity of the honeycomb structure 14b is preferably 78% or more. When the porosity of the honeycomb structure 14b is 78% or more, the honeycomb structure 14b can easily absorb the change in thickness caused by the expansion and contraction of the battery cells 11a. The porosity of the honeycomb structure 14b is not particularly limited, but is, for example, 48% or more and 90% or less.

[0034] The thickness of the honeycomb structure 14b at SOC 100% is not particularly limited, but is, for example, 0.5 mm or more and 1.0 mm or less.

[0035] The material constituting the honeycomb structure 14b is not particularly limited, but examples thereof include rubbers such as silicone rubber (VMQ), ethylene propylene diene rubber (EPDM), fluororubber (FKM), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), chloroprene rubber (CR), acrylic rubber (ACM), butyl rubber (IIR), urethane rubber (U), chlorosulfonated polyethylene rubber (CSM), and epichlorohydrin rubber (ECO).

[0036] The Young's modulus of the rigid member 14c is preferably 150 GPa or more. When the Young's modulus of the rigid member is 150 GPa or more, the uniformity of the surface pressure of the cushion material 14 is increased. The Young's modulus of the rigid member 14c is not particularly limited, but is, for example, 35 GPa or more and 210 GPa or less.

[0037] The material constituting the rigid member 14c is not particularly limited, but may be, for example, stainless steel.

[0038] In addition, a member having a recess or a through hole other than the honeycomb structure 14b may be used as the second elastic member. The member having the recess or the through hole can be manufactured, for example, by using a mold, a 3D printer, or a precision water jet. The cross-sectional shape of the recess or the through hole can be a triangle, a rectangle, or the like, in addition to a hexagon.

[0039] The diameter of the recess or through hole is preferably 4 mm or less. When the diameter of the recess or through hole is 4 mm or less, the uniformity of the surface pressure of the cushion material 14 is increased. The diameter of the recess or through hole is not particularly limited, but is, for example, 2 mm or more.

[0040] FIG. 4 shows a modified example of the cushion material 14. As shown in FIG.

[0041] The cushion material 14A is similar to the cushion material 14, except that a member in which a plurality of arc-shaped leaf springs 21 are arranged in parallel as a second elastic member is disposed between a pair of foam bodies 14a.

[0042] The Young's modulus of the leaf spring 21 is preferably 35 GPa or more. If the Young's modulus of the leaf spring 21 is 35 GPa or more, the leaf spring 21 can easily absorb the change in thickness caused by the expansion and contraction of the battery cell 11a. The Young's modulus of the leaf spring 21 is not particularly limited, but is, for example, 200 GPa or less.

[0043] The material constituting the leaf spring 21 is not particularly limited, but examples thereof include metals such as stainless steel and carbon steel, resins such as epoxy resin, phenol resin, and nylon resin, and fiber reinforced plastic (FRP).

[0044] Note that the second elastic member may be a member having a leaf spring structure other than the member in which a plurality of arc-shaped leaf springs 21 are arranged in parallel. For example, instead of arranging a plurality of arc-shaped leaf springs 21 in parallel, a wavy leaf spring 31 (see FIG. 5) may be arranged. This makes it easier to manufacture the cushioning material.

[0045] The battery cell 11a is not particularly limited, but examples thereof include solid-state battery cells such as all-solid-state lithium ion battery cells and all-solid-state lithium metal battery cells, and lithium metal battery cells. Among these, solid-state battery cells are preferred.

[0046] The following describes the case where the battery cell 11a is an all-solid-state lithium metal battery cell.

[0047] 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, which are laminated in this order.

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

[0049] The positive electrode mixture layer contains a positive electrode active material, and may further contain a solid electrolyte, a conductive assistant, a binder, and the like.

[0050] The positive electrode active material is not particularly limited as long as it is capable of absorbing and releasing 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 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、 Examples include LiCoO4, LiMn2O4, LiNiO2, LiFePO4, lithium sulfide, and sulfur.

[0051] 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.

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

[0053] Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and the above embodiment may be modified as appropriate within the scope of the spirit of the present invention. EXAMPLES

[0054] Examples of the present invention will be described below, but the present invention is not limited to these examples.

[0055] [Example 1] The cushioning material 14 (see FIG. 2) was produced using a 0.14 mm thick polyurethane plate-like member as the foam 14a, a 2.8 mm thick, 4 mm diameter silicone rubber plate-like member as the honeycomb structure 14b, and a 0.1 mm thick stainless steel plate-like member as the rigid member 14c.

[0056] [Example 2] A cushioning material was produced in the same manner as in Example 1, except that a 0.28 mm thick polyurethane plate-like member was used as the foam 14a.

[0057] [Example 3] A cushioning material was produced in the same manner as in Example 1, except that a 0.70 mm thick polyurethane plate-like member was used as the foam 14a.

[0058] [Comparative Example 1] A cushioning material was produced in the same manner as in Example 3, except that the rigid member 14c was not used.

[0059] [Comparative Example 2] A cushioning material was produced in the same manner as in Example 1, except that a 4 mm thick polyurethane plate-like member was used as the foam 14a, and the rigid member 14c was not used.

[0060] [Comparative Example 3] A 4 mm thick polyurethane plate member was used as the cushioning material.

[0061] [Uniformity of cushioning surface pressure] After placing the cushioning material on the sensor sheet of a pressure distribution measurement system (tactile sensor system) (manufactured by NITTA), a surface pressure of 1.5 MPa was applied to the entire surface of the cushioning material, and the area ratio where the surface pressure was 1 MPa or more was determined to evaluate the uniformity of the surface pressure of the cushioning material.

[0062] Table 1 shows the evaluation results of the uniformity of the surface pressure of the cushioning material.

[0063] [Table 1]

[0064] It can be seen from Table 1 that the cushioning materials of Examples 1 to 3 have high uniformity of surface pressure. In addition, the cushioning materials of Examples 1 to 3 have small foam thicknesses, so that the energy density of the battery module is high.

[0065] In contrast, the cushioning material of Comparative Example 1 does not use a rigid member, and therefore has low surface pressure uniformity. Also, the cushioning materials of Comparative Examples 2 and 3 have a large foam thickness, and therefore the energy density of the battery module is low. [Explanation of symbols]

[0066] 10 Battery Module 11 Battery cell stack 11a battery cell 12 End plate 13 Binding Bar 14 Cushioning material 14a Foam 14b Honeycomb structure 14c Rigid members 21 Leaf spring 31 Wavy leaf spring

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 in a stacking direction of the battery cell stack; a cushioning material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped member; the battery cell is an all-solid-state battery cell; the cushion material has a pair of first elastic members arranged on both outer sides in a stacking direction of the battery cell stack, a second elastic member arranged between the pair of first elastic members, and a rigid member arranged between the first elastic members and the second elastic members, the first elastic member is a foam containing a resin, The second elastic member is a honeycomb structure containing rubber.

2. A battery module as described in claim 1, wherein the honeycomb structure has a through hole having a diameter of 4 mm or less.

3. a battery cell stack in which a plurality of battery cells are stacked; A pair of plate-shaped members provided at both ends in a stacking direction of the battery cell stack; a cushioning material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped member; the battery cell is an all-solid-state battery cell; the cushion material has a pair of first elastic members arranged on both outer sides in a stacking direction of the battery cell stack, a second elastic member arranged between the pair of first elastic members, and a rigid member arranged between the first elastic members and the second elastic members, the first elastic member is a foam containing a resin, The second elastic member is a member in which a plurality of arc-shaped leaf springs made of resin or fiber-reinforced plastic are arranged in parallel.

4. a battery cell stack in which a plurality of battery cells are stacked; A pair of plate-shaped members provided at both ends in a stacking direction of the battery cell stack; a cushioning material disposed between the plurality of battery cells and / or between the battery cell stack and the plate-shaped member; the battery cell is an all-solid-state battery cell; the cushion material has a pair of first elastic members arranged on both outer sides in a stacking direction of the battery cell stack, a second elastic member arranged between the pair of first elastic members, and a rigid member arranged between the first elastic members and the second elastic members, the first elastic member is a foam containing a resin, The second elastic member is a corrugated leaf spring containing resin or fiber-reinforced plastic.

5. The battery module according to claim 1 , wherein the first elastic member has a Poisson's ratio of 0.3 or less.

6. The battery module of claim 5 , wherein the rigid member comprises stainless steel.

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