Battery module

Abstract

To provide a battery module capable of suppressing an electrical short circuit caused by ejection from a battery cell.SOLUTION: A battery includes a plurality of battery cells arranged in a first direction and a cover member provided on the plurality of battery cells. Each of the plurality of battery cells includes a housing having a gas release valve and an electrode terminal provided on the housing. The cover member includes a first region and a second region having a strength lower than that of the first region. The first region is located above at least one of the electrode terminals. The second region is located above at least one of the gas release valves and includes a notch formed in the cover member.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] This technology relates to a battery module.

Background Art

[0002] When the pressure inside the exterior can of a battery cell constituting a battery module rises, a technology for discharging the internal gas by opening a part of the exterior can has been conventionally known. Similarly, when the pressure inside the case of a battery pack rises, a technology for discharging the internal gas by opening a part of the pack case has also been conventionally known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a battery module having a structure in which a cover member is provided over a plurality of battery cells, when a part of the exterior can is opened as the pressure inside the exterior can of the battery cell rises, if the cover member is blown off by the gas ejected from the exterior can, bus bars, voltage detection lines, etc. will be exposed. If ejecta containing metal from inside the exterior can adheres to the exposed bus bars, voltage detection lines, etc., an electrical short circuit may occur.

[0005] An object of this technology is to provide a battery module capable of suppressing an electrical short circuit caused by ejecta from a battery cell.

Means for Solving the Problems

[0006] This technology provides the following battery modules. [1] A battery module comprising a plurality of battery cells arranged in a first direction and a cover member provided on the plurality of battery cells, each of the plurality of battery cells including a housing having a gas discharge valve and electrode terminals provided on the housing, the cover member including a first region and a second region having less strength than the first region, the first region located on at least one electrode terminal and the second region located on at least one gas discharge valve, and including a notch formed in the cover member.

[0007] [2] The battery module according to [1], wherein the second region extends in the first direction so as to be located on at least a plurality of gas exhaust valves.

[0008] [3] The battery module according to [1] or [2], wherein the notch is formed to surround the upper region of the gas exhaust valve. [Effects of the Invention]

[0009] According to this technology, in a cover member provided on multiple battery cells, a second region with relatively lower strength is provided on the gas discharge valve. This allows for selective destruction of the cover member located in the second region during gas discharge, thereby protecting the first region located on the electrode terminals. As a result, electrical short circuits caused by ejected material from the battery cells can be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] This diagram shows the basic configuration of a battery module. [Figure 2] This is a perspective view showing a battery cell. [Figure 3] This is a perspective view showing a wiring module installed on a battery module. [Figure 4] This is a top view of the battery module. [Figure 5] This diagram schematically illustrates the process of gas being released from a battery cell. [Figure 6] This is a diagram schematically showing the periphery of the second region of the plate member. [Figure 7] This is a perspective view showing a modified example of the second region. [Figure 8] This is a cross-sectional view showing the second region shown in FIG. 7. [Figure 9] This is a cross-sectional view (Part 1) showing a further modified example of the second region of the plate member. [Figure 10] This is a cross-sectional view (Part 2) showing a further modified example of the second region of the plate member. [Figure 11] This is a cross-sectional view (Part 3) showing a further modified example of the second region of the plate member. [Figure 12] This is a cross-sectional view (Part 4) showing a further modified example of the second region of the plate member. [Figure 13] This is a cross-sectional view (Part 5) showing a further modified example of the second region of the plate member.

MODE FOR CARRYING OUT THE INVENTION

[0011] The embodiments of the present technology will be described below. In the following description, the same or corresponding parts may be denoted by the same reference numerals, and the description thereof may not be repeated.

[0012] In the embodiments described below, when referring to the number, amount, etc., unless otherwise specified, the scope of the present technology is not necessarily limited to such number, amount, etc. Further, in the following embodiments, each component is not necessarily essential for the present technology, unless otherwise specified. Also, the present technology is not limited to those that necessarily exhibit all the effects described in the present embodiments.

[0013] In this specification, the descriptions of "comprise", "include", and "have" are in an open-ended format. That is, when a certain configuration is included, other configurations other than the said configuration may or may not be included.

[0014] In addition, in this specification, when geometric terms and terms representing positional and directional relationships, such as "parallel", "orthogonal", "diagonal 45°", "coaxial", "along", etc., are used, these terms allow for manufacturing errors or slight variations. In this specification, when terms representing relative positional relationships, such as "upper side", "lower side", etc., are used, these terms are used to indicate the relative positional relationship in one state, and depending on the installation direction of each mechanism (for example, reversing the entire mechanism upside down, etc.), the relative positional relationship can be reversed or rotated at an arbitrary angle.

[0015] In this specification, "battery" is not limited to lithium-ion batteries and may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, "electrode" may be a general term for the positive electrode and the negative electrode. Also, "electrode plate" may be a general term for the positive electrode plate and the negative electrode plate.

[0016] In this specification, the "battery cell" can be mounted in a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a battery electric vehicle (BEV), etc. However, the use of the "battery cell" is not limited to in-vehicle use.

[0017] FIG. 1 is a diagram showing the basic configuration of the assembled battery 1. As shown in FIG. 1, the assembled battery 1 includes battery cells 100, end plates 200, and a restraint member 300.

[0018] A plurality of battery cells 100 are provided so as to be arranged in the Y-axis direction (the first direction). Thereby, a stack of battery cells 100 is formed. The battery cell 100 includes an electrode terminal 110. A separator (not shown) is interposed between the plurality of battery cells 100. The plurality of battery cells 100 sandwiched between the two end plates 200 are pressed by the end plates 200 and restrained between the two end plates 200.

[0019] The end plates 200 are positioned at both ends of the battery pack 1 in the Y-axis direction. The end plates 200 are fixed to a base such as a case that houses the battery pack 1. The restraining member 300 connects the two end plates 200 to each other.

[0020] When a compressive force in the Y-axis direction is applied to a stack of multiple battery cells 100 and end plates 200, the restraining member 300 is fixed to the end plate 200, and then the compressive force is released, a tensile force acts on the restraining member 300 connecting the two end plates 200. In reaction to this, the restraining member 300 presses the two end plates 200 toward each other.

[0021] Figure 2 is a perspective view showing a battery cell 100. As shown in Figure 2, the battery cell 100 has a rectangular shape. The battery cell 100 has electrode terminals 110 and a housing 120 (outer casing). In other words, the battery cell 100 is a rectangular secondary battery cell.

[0022] The electrode terminals 110 are formed on the housing 120. The electrode terminals 110 have a positive electrode terminal 111 and a negative electrode terminal 112 that are aligned along the X-axis direction (second direction) which is perpendicular to the Y-axis direction (first direction). The positive electrode terminal 111 and the negative electrode terminal 112 are spaced apart from each other in the X-axis direction.

[0023] The housing 120 has a rectangular parallelepiped shape and forms the external appearance of the battery cell 100. The housing 120 includes a case body 120A that houses electrode bodies and electrolyte (not shown), and a sealing plate 120B that seals the opening of the case body 120A. The sealing plate 120B is joined to the case body 120A by welding.

[0024] The housing 120 has a top surface 121, a bottom surface 122, a first side surface 123, a second side surface 124, and two third side surfaces 125. The housing 120 is provided with a gas discharge valve 126.

[0025] The upper surface 121 is a plane perpendicular to the Z-axis direction (third direction), which is perpendicular to the Y-axis direction and the X-axis direction. Electrode terminals 110 are arranged on the upper surface 121. The lower surface 122 faces the upper surface 121 along the Z-axis direction.

[0026] Each of the first side 123 and the second side 124 consists of a plane perpendicular to the Y-axis direction. Each of the first side 123 and the second side 124 has the largest area among the multiple sides of the housing 120. Each of the first side 123 and the second side 124 has a rectangular shape when viewed in the Y-axis direction. Each of the first side 123 and the second side 124 has a rectangular shape when viewed in the Y-axis direction, with the X-axis direction being the longitudinal direction and the Z-axis direction being the short direction.

[0027] Multiple battery cells 100 are stacked such that the first sides 123 and second sides 124 face each other between adjacent battery cells 100, 100 in the Y-axis direction. As a result, the positive terminals 111 and negative terminals 112 are arranged alternately in the Y-axis direction in which the multiple battery cells 100 are stacked.

[0028] The gas discharge valve 126 is located on the top surface 121. The gas discharge valve 126 discharges gas to the outside of the housing 120 when the temperature of the battery cell 100 rises (thermal runaway) and the internal pressure of the housing 120 exceeds a predetermined value due to the gas generated inside the housing 120.

[0029] Figure 3 is a perspective view showing the battery pack 1 with a wiring module installed. As shown in Figure 3, a plate member 400 is placed on the battery pack 1, and a flexible printed circuit board 500 is installed on the plate member 400. The flexible printed circuit board 500 can be electrically connected to external devices via a connector 600. A cover member 700 is provided on the plate member 400 so as to cover the flexible printed circuit board 500. In addition to the flexible printed circuit board 500, electric wires or flexible flat cables (FFCs) may be used as voltage detection lines.

[0030] Figure 4 is a top view of the battery module. As shown in Figure 4, the cover member 700 provided on top of the multiple battery cells 100 includes a first region 710 and a second region 720.

[0031] The first region 710 extends in the Y-axis direction so as to be located on multiple electrode terminals 110. The first region 710 only needs to be formed so as to be located on at least one electrode terminal 110.

[0032] The second region extends in the Y-axis direction so as to be located over multiple gas exhaust valves 126. The second region 720 only needs to be formed so as to be located over at least one gas exhaust valve 126. The second region 720 is formed to have lower strength than the first region 710.

[0033] Figure 5 schematically shows the state in which gas is discharged from the battery cell 100. As shown in Figure 5, when the gas discharge valve 126 is opened due to an increase in the internal pressure of the housing 120 of the battery cell 100, the cover member 700 is blown off by the gas ejected from the gas discharge valve 126, exposing live components such as busbars and voltage detection lines. If ejected material containing metal from inside the housing 120 adheres to the live components, an electrical short circuit may occur. These live components are electrically connected to the electrode terminals 110 of the battery cell 100, and are therefore located at a position spaced away from the center in the X-axis direction (second direction).

[0034] In contrast, in the battery module according to this embodiment, a second region 720 with relatively low strength is provided on the gas discharge valve 126 in the cover member 700 provided on the plurality of battery cells 100. Therefore, when gas is ejected from the gas discharge valve 126, the second region 720 of the cover member 700 located on the gas discharge valve 126 can be selectively destroyed. As a result, the first region 710 located on the electrode terminal 110 can be protected, that is, the first region 710 can be kept on the live electrical member. Thus, electrical short circuits caused by ejected material from the battery cells 100 adhering to the live electrical member can be suppressed.

[0035] Figure 6 is a schematic diagram showing the area around the second region 720. In the example shown in Figure 6, the cover member 700 has a notch 721 formed to surround the upper region of the gas discharge valve 126. This selectively destroys the second region 720 when gas is ejected from the gas discharge valve 126, protecting the first region 710 of the cover member.

[0036] Figure 7 is a perspective view showing a modified example of the second region 720. Figure 8 is a cross-sectional view showing the second region 720 shown in Figure 7. In the modified examples of Figures 7 and 8, a substantially circular groove 722 is formed in the cover member 700, thereby selectively destroying the second region 720 when gas is ejected from the gas discharge valve 126, and protecting the first region 710 of the cover member.

[0037] Figures 9 to 13 are cross-sectional views showing further variations of the second region 420. As shown in Figures 9 and 10, the second region 720 may be formed by forming a thin-walled portion 723 in a part of the cover member 700, or, as shown in Figure 11, the second region 720 may be formed by forming a groove portion 722 with a different cross-sectional shape than that shown in Figure 8.

[0038] As shown in Figure 12, the second region 720 may be formed by detachably providing a separate part 724 (lid) made of another material such as resin or rubber into the hole in the cover member 700, or, as shown in Figure 13, the second region 720 may be formed by attaching a separate part 725 made of another material such as tape or net into the hole provided in the cover member 700.

[0039] Furthermore, the second region 720 may be formed by constructing the second region 720 of the cover member 700 from a material with relatively lower strength than the first region 710.

[0040] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0041] 1. Battery set, 100. Battery cell, 110. Electrode terminal, 111. Positive terminal, 112. Negative terminal, 120. Housing, 120A. Case body, 120B. Sealing plate, 121. Top surface, 122. Bottom surface, 123. First side surface, 124. Second side surface, 125. Third side surface, 126. Gas discharge valve, 200. End plate, 300. Restraining member, 400. Plate member, 420. Second region, 500. Flexible printed circuit board, 600. Connector, 700. Cover member, 710. First region, 720. Second region, 721. Notch, 722. Groove, 723. Thin-walled section, 724, 725. Separate parts.

Claims

1. Multiple battery cells arranged in the first direction, The system comprises a cover member provided on top of the plurality of battery cells, Each of the plurality of battery cells includes a housing having a gas discharge valve and electrode terminals provided on the housing, The housing has an upper surface extending in a planar direction including the first direction and a second direction perpendicular to the first direction, and the gas exhaust valve is provided on the upper surface. The cover member is provided so as to face the upper surface in a third direction perpendicular to the first and second directions, The cover member includes a first region and a second region having lower strength than the first region. The first region is located on at least one of the electrode terminals, The second region includes a notch or groove formed in the cover member so as to surround the upper region of at least one of the gas discharge valves, A battery module in which, at the boundary between the inner and outer circumferences of the notch or groove surrounding the upper region, the cover member does not protrude toward the plurality of battery cells in the third direction.

2. The battery module according to claim 1, wherein the second region extends in the first direction so as to be located on at least a plurality of the gas exhaust valves.

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