Electric storage device

Abstract

To provide a power storage device which allows improvement in insulation of a housing that houses battery cells.SOLUTION: A power storage device 1 comprises: a laminate 10 in which a plurality of battery cells 11 are laminated; a housing 20 which houses the laminate 10; and an insulation sheet 31 which is disposed between a ceiling surface 24 of the housing 20 and the laminate 10. The ceiling surface 24 has an exposed region 35 which is not covered with the insulation sheet 31. The insulation sheet 31 has a protrusion 34 which protrudes downward. In plan view, the protrusion 34 is disposed between the laminate 10 and the exposed region 35.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a power storage device.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2013-229266 (Patent Document 1) discloses a battery module as a power storage device. The battery module includes batteries arranged in a stack. A housing surrounding the batteries is formed by a pair of end plates and a pair of bus bar modules.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the electrolytic solution leaks from the battery, there is a possibility that the electrode tab and the housing are short-circuited through the electrolytic solution and the housing has a potential. If both the housings of adjacent battery modules constituting the assembled battery have a potential, a circuit may be formed and heat may be generated. In addition, the workability when handling the housing having a potential may be reduced.

[0005] The present disclosure proposes a power storage device capable of improving the insulation of the housing that houses the battery cells.

Means for Solving the Problems

[0006] According to the present disclosure, there is proposed a power storage device including a laminate in which a plurality of battery cells are laminated, a housing that houses the laminate, and an insulating sheet disposed between the ceiling surface of the housing and the laminate. The ceiling surface has an exposed area that is not covered with the insulating sheet. The insulating sheet has a convex portion that protrudes downward. The convex portion is disposed between the laminate and the exposed area in a plan view.

[0007] Even if the conductive liquid present in the housing flows along the insulating sheet toward the exposed area, when the liquid reaches the convex portion, the liquid is guided by the convex portion and falls downward. Since the liquid is prevented from reaching the exposed area by the convex portion, a short circuit between the laminate and the housing can be prevented. Therefore, the insulation of the housing that houses the battery cell can be improved.

[0008] In the above-described power storage device, the convex portion may have a shape extending in a rib shape. Thereby, it is possible to reliably prevent the conductive liquid from reaching the exposed area.

[0009] In the above-described power storage device, the insulating sheet may have a bent portion where the peripheral edge of the insulating sheet is bent, and the bent portion may form the convex portion. In this way, the manufacturing of the convex portion becomes easy. Moreover, a convex portion having a rib shape can be reliably formed.

[0010] In the above-described power storage device, the laminate has a connection portion that connects two battery cells, and the convex portion may be disposed between the connection portion and the exposed area in a plan view. Since it is possible to suppress the conductive liquid from falling from the convex portion to the connection portion, it is possible to suppress a short circuit between the connection portions adjacent to each other in the stacking direction of the battery cells.

[0011] In the above-described power storage device, the housing has a side wall that constitutes a side surface of the housing and a top wall that constitutes a top surface of the housing. The lower surface of the top wall constitutes a ceiling surface. The housing further has a welded portion where the side wall and the top wall are welded, and an exposed area may be provided at a peripheral edge portion of the top wall. Since there is no insulating sheet at the welded portion, welding defects can be suppressed.

Effects of the Invention

[0012] According to the power storage device of the present disclosure, the insulation of the housing that houses the battery cell can be improved.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

[0014] Hereinafter, embodiments will be described with reference to the drawings. In the following description, the same components are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0015] FIG. 1 is a cross-sectional view showing a schematic configuration of a power storage device 1 according to an embodiment. The power storage device 1 is mounted on and used in, for example, a vehicle. Examples of the vehicle include a hybrid vehicle, a plug-in hybrid vehicle, an electric vehicle, and a fuel cell vehicle. A battery pack in which a plurality of power storage devices 1 are arranged and made into one assembly is mounted on the vehicle.

[0016] The power storage device 1 shown in FIG. 1 includes a laminate 10 in which a plurality of battery cells 11 are laminated in the stacking direction. The stacking direction of the battery cells 11 is the vertical direction. Each of the plurality of battery cells 11 is a secondary battery such as a lithium ion battery or a nickel hydrogen battery. An electrode body 12 is housed inside the exterior body of each battery cell 11. The electrode body 12 is formed, for example, by laminating a positive electrode and a negative electrode with a separator interposed therebetween and further winding them in a cylindrical shape. The electrode body is not limited to the wound type and may be a stacked type. The electrode body 12 is immersed in an electrolytic solution. An electrolytic solution is enclosed inside the exterior body of the battery cell 11.

[0017] The laminate 10 has a connection part 13 that electrically connects two adjacent battery cells 11 in the stacking direction. When two battery cells 11 are connected in series, the positive electrode terminal of one battery cell 11 and the negative electrode terminal of the other battery cell 11 are electrically connected. The connection part 13 is welded to, for example, the positive electrode terminal and the negative electrode terminal.

[0018] The laminate 10 has a pair of main terminals 14, 14. One of the pair of main terminals 14 is the positive output terminal of the laminate 10, and the other is the negative output terminal of the laminate 10. The battery cells 11 where the main terminals 14 are provided are arranged farthest apart in the stacking direction. The main terminals 14 are arranged to penetrate the housing 20. A gasket 15 is provided at the location where the main terminal 14 penetrates the housing 20. The gasket 15 electrically insulates the main terminal 14 from the housing 20 and seals the through-hole formed in the housing 20 for the main terminal 14 to penetrate, preventing the intrusion of moisture from the outside into the housing 20.

[0019] The power storage device 1 includes a housing 20 that houses the laminate 10. The housing 20 has a bottom wall 21, side walls 22, and a top wall 23. The bottom wall 21, side walls 22, and top wall 23 are formed of a conductive material. The bottom wall 21, side walls 22, and top wall 23 are formed of a metal material represented by, for example, an aluminum alloy.

[0020] The bottom wall 21 is arranged below the laminate 10. The bottom wall 21 constitutes the lower surface of the housing 20. The side walls 22 cover the laminate 10 from the sides. The side walls 22 constitute the side surfaces of the housing 20. The side walls 22 have inner wall surfaces 26. The inner wall surfaces 26 face the inner space of the housing 20. The inner wall surfaces 26 face the laminate 10. In the housing 20 shown in FIG. 1, the bottom wall 21 and the side walls 22 are integrally formed. The bottom wall 21 and the side walls 22 form a housing case that opens upward. The laminate 10 is housed in the housing case.

[0021] The top wall 23 is disposed above the laminate 10. The top wall 23 constitutes the upper surface of the housing 20. The top wall 23 is formed as a cover that closes the opening of the housing case formed by the bottom wall 21 and the side wall 22. The top wall 23 covers the laminate 10 from above. The lower surface of the top wall 23 constitutes the ceiling surface 24 of the housing 20. The ceiling surface 24 faces the internal space of the housing 20. The ceiling surface 24 faces downward. The ceiling surface 24 faces the laminate 10.

[0022] The upper edge of the side wall 22 and the peripheral edge of the top wall 23 are joined by welding. The housing 20 has a welded portion 25 where the side wall 22 and the top wall 23 are welded. By welding the top wall 23 to the housing case, the housing case is sealed. FIG. 2 is a perspective view showing an enlarged view of the vicinity of the welded portion 25 shown in FIG. 1. In FIG. 2, the vicinity of the joint between the side wall 22 and the top wall 23 of the housing 20 turned upside down is shown. For simplicity, the laminate 10 is not shown in FIG. 2. The welded portion 25 extends along the upper edge of the side wall 22 and along the peripheral edge of the top wall 23.

[0023] The power storage device 1 further includes insulating sheets 31 and 32. The insulating sheets 31 and 32 are interposed between the laminate 10 and the inner surface of the housing 20, and electrically insulate the laminate 10 and the housing 20. The insulating sheets 31 and 32 are formed of an electrically insulating material typified by a resin material. Typically, the insulating sheets 31 and 32 are formed of a material resistant to electrolytic solution, such as polypropylene, polyamide, and polytetrafluoroethylene. The insulating sheets 31 and 32 are formed of a material chemically stable with respect to a solvent used in an electrolytic solution such as dimethyl carbonate.

[0024] The insulating sheet 31 is disposed between the ceiling surface 24 of the housing 20 and the laminate 10. The insulating sheet 31 covers a part of the ceiling surface 24 of the housing 20. The insulating sheet 32 covers the floor surface of the housing 20 and a part of the inner wall surface 26 of the housing 20. By covering the entire bottom surface of the housing 20 and the inner wall surface 26 with the integral insulating sheet 32, the insulation of the housing 20 is improved. A sheet-like resin material may be attached to the inner surface of the housing 20 with an adhesive to form the insulating sheets 31 and 32. The insulating sheets 31 and 32 may be formed by coating the inner surface of the housing 20 with a resin material.

[0025] The ceiling surface 24 has an exposed area 35 that is not covered by the insulating sheet 31. The inner wall surface 26 has an exposed area 36 that is not covered by the insulating sheet 32. Specifically, the exposed area 35 is provided at the peripheral edge of the ceiling wall 23. The exposed area 36 is provided at the upper edge of the side wall 22. As shown in FIG. 2, the exposed area 35 is formed along the peripheral edge of the ceiling wall 23, and the exposed area 36 is formed along the upper edge of the side wall 22. The welding portion 25 that joins the upper edge of the side wall 22 and the peripheral edge of the ceiling wall 23 is not covered by the insulating sheet 31 and is not covered by the insulating sheet 32.

[0026] The insulating sheet 31 has a convex portion 34 that protrudes downward. As shown in FIG. 2, the convex portion 34 has a shape that extends in a rib shape along the peripheral edge of the ceiling wall 23. The convex portion 34 is disposed between the laminate 10 of the battery cell 11 and the exposed area 35 in plan view. The convex portion 34 is disposed between the connection portion 13 and the exposed area 35 in plan view. The convex portion 34 is disposed between the laminate 10 of the battery cell 11 and the welding portion 25. The convex portion 34 is disposed between the connection portion 13 and the welding portion 25.

[0027] The insulating sheet 31 has a bent portion 33 in which the peripheral edge of the insulating sheet 31 is bent downward, and the bent portion 33 forms the convex portion 34. The bent portion 33 is bent with respect to the planar ceiling surface 24. The bent portion 33 is bent perpendicular to the ceiling surface 24.

[0028] As shown in FIG. 1, the power storage device 1 of the embodiment described above includes an insulating sheet 31. The insulating sheet 31 is disposed between the laminate 10 of the battery cells 11 and the ceiling surface 24 of the housing 20 that houses the laminate 10. The ceiling surface 24 of the housing 20 has an exposed area 35 that is not covered by the insulating sheet 31. The insulating sheet 31 has a convex portion 34 that protrudes downward. The convex portion 34 is disposed between the laminate 10 and the exposed area 35 in a plan view.

[0029] The ceiling surface 24 of the housing 20 is covered with the insulating sheet 31, and the floor surface and the inner wall surface 26 are covered with the insulating sheet 32. The laminate 10 of the battery cells 11 and the housing 20 can be suitably electrically insulated by the insulating sheets 31 and 32. There may be a case where a conductive liquid such as an electrolytic solution leaked from the battery cell 11 or moisture infiltrated from the outside exists in the housing 20. Even in that case, a short circuit between the connection portion 13 connecting the battery cells 11 and the housing 20 through the liquid is suppressed.

[0030] When the side wall 22 and the top wall 23 of the housing 20 are joined by welding, the resin material attached to the inner surface of the housing 20 may be carbonized by the welding heat to have conductivity and the insulation property may be deteriorated, or the resin may melt and vaporize and the gas may be involved during welding to cause defects such as holes in the welded portion. An exposed area 35 where the insulating sheet 31 is not formed is provided at the peripheral edge of the top wall 23, and an exposed area 36 where the insulating sheet 32 is not formed is provided at the upper edge of the side wall 22, and the welded portion 25 is configured to have no resin material. Thereby, even when the side wall 22 and the top wall 23 are joined by welding, it is possible to suppress the occurrence of welding defects.

[0031] A convex portion 34 is disposed between the laminate 10 of the battery cells 11 and an exposed area 35 on the inner surface of the housing 20 that is not covered by the insulating sheet 31. Even if a liquid having conductivity such as an electrolytic solution flows along the insulating sheet 31 toward the exposed area 35, when the liquid reaches the convex portion 34, the liquid is guided by the convex portion 34 and falls downward. When the conductive liquid reaches the exposed area 35, there is a possibility that the connection portion 13 and the housing 20 are short-circuited and the housing 20 has an electric potential. However, since the liquid is prevented from reaching the exposed area 35 by the convex portion 34, a short circuit between the connection portion 13 and the housing 20 can be prevented. Therefore, the insulation of the housing 20 that houses the battery cells 11 can be improved.

[0032] As shown in FIG. 2, the convex portion 34 may have a shape extending in a rib shape. The rib-shaped convex portion 34 functions as a weir that dams up the conductive liquid flowing along the insulating sheet 31 toward the exposed area 35. Thereby, it is possible to surely suppress the conductive liquid from reaching the exposed area 35.

[0033] As shown in FIGS. 1 and 2, the insulating sheet 31 may have a bent portion 33 whose periphery is bent, and the bent portion 33 may form the convex portion 34. In this way, the manufacture of the convex portion 34 becomes easy. Moreover, the convex portion 34 having a rib shape can be surely formed.

[0034] As shown in FIG. 1, the laminate 10 has a connection portion 13 that connects two battery cells 11, and the convex portion 34 may be disposed between the connection portion 13 and the exposed area 35 in a plan view. By disposing the convex portion 34 in this way, it is possible to suppress the conductive liquid from falling from the convex portion 34 to the connection portion 13, and it is possible to suppress a short circuit between the connection portions 13 adjacent to each other in the stacking direction of the battery cells 11.

[0035] As shown in FIGS. 1 and 2, the housing 20 has a welded portion 25 where a side wall 22 constituting the side surface of the housing 20 and a top wall 23 constituting the top surface of the housing 20 are welded, and an exposed region 35 may be provided at the peripheral edge of the top wall 23. A configuration in which the insulating sheet 31 does not exist in the welded portion 25 is realized, whereby welding defects can be more reliably suppressed.

[0036] In the above description, an example in which the exposed region 35 is formed in the welded portion 25 to prevent welding defects has been described. When there are portions on the inner surface of the housing 20 that are not covered by the insulating sheets 31 and 32 other than the welded portion 25, by providing a structure for dropping liquid downward in front of the portion, it is possible to suppress the conductive liquid from reaching the portion. Therefore, the effect of improving the insulation of the housing 20 can be obtained in the same manner.

[0037] The battery cell 11 is not limited to a liquid-based battery in which an electrolyte is enclosed inside. Even when the battery cell 11 is a all-solid-state battery, due to condensation inside the housing 20 or unintended ingress of moisture from the outside, there may be a conductive liquid inside the housing 20. Even in this case, by disposing the convex portion 34 between the battery cell 11 and the exposed region 35, it is possible to suppress the conductive liquid from reaching the exposed region 35 and improve the insulation of the housing 20.

[0038] In the laminate 10, the stacking direction of the battery cells 11 is not limited to the vertical direction. The insulating sheet 31 of the embodiment may be applied to the ceiling surface 24 of the housing 20 that houses the laminate 10 in which the battery cells 11 are stacked in the horizontal direction.

[0039] The convex portion 34 is not limited to an example formed by bending the peripheral edge of the insulating sheet 31. If the insulating sheet 31 has a convex shape protruding downward at the peripheral edge, the convex shape can guide the liquid and drop it downward. The convex portion 34 does not have to have a rib shape. For example, a configuration in which a plurality of columnar convex portions 34 are scattered along the peripheral edge of the insulating sheet 31 may be used.

[0040] Next, an outline of the manufacturing method of the power storage device 1 of the embodiment will be described. FIG. 3 is a flowchart showing the manufacturing method of the power storage device 1.

[0041] In step S1, a housing case is formed. A plate-like member constituting the bottom wall 21 shown in FIG. 1 and a plate-like member constituting the side wall 22 are prepared, and by joining these plate-like members, a box-shaped housing case with one surface open can be formed.

[0042] In step S2, an insulating sheet 32 is formed on the inner surface of the housing case. The insulating sheet 32 may be formed by attaching a sheet-like resin material to the inner surface of the housing case with an adhesive, or the insulating sheet 32 may be formed by coating the inner surface of the housing case with a resin material. An exposed area 36 where the inner surface of the housing case is not covered with the insulating sheet 32 is formed at the edge of the opening of the housing case.

[0043] In parallel with steps S1 and S2, in step S3, a cover is prepared. A plate-like member constituting the top wall 23 shown in FIG. 1 is prepared.

[0044] In step S4, an insulating sheet 31 is formed on the surface of the cover that constitutes the ceiling surface 24. The insulating sheet 31 may be formed by attaching a sheet-like resin material to the surface of the cover with an adhesive, or the insulating sheet 31 may be formed by coating the surface of the cover with a resin material. The periphery of the formed insulating sheet 31 is bent to form a bent portion 33. An exposed area 35 not covered with the insulating sheet 31 is formed at the peripheral portion of the cover. By bending the insulating sheet 31 to form a convex portion 34, the positioning of the convex portion 34 with respect to the cover is facilitated.

[0045] In step S5, the battery cells 11 are stacked on the cover arranged so that the surface on which the insulating sheet 31 is formed faces upward. The terminals of two adjacent battery cells 11 are electrically connected by a connection portion 13 to form a laminate 10.

[0046] In step S6, a housing case is placed over the laminate 10 of the battery cell 11. In step S7, the cover is welded to the housing case to seal the opening of the housing case, thereby forming the housing 20. The main terminal 14 is arranged so as to penetrate the side wall 22 of the housing 20 and be drawn out to the outside, and a gasket 15 is provided around the main terminal 14. The housing 20 is turned upside down, and the manufacturing of the power storage device 1 shown in FIG. 1 is completed.

[0047] Although it is also possible to form the laminate 10 by sequentially accommodating the battery cells 11 inside the housing case, in that case, a space for the equipment to pass through when moving the battery cells 11 inside the housing case will exist as a hollow space between the laminate 10 and the inner surface of the housing case. According to the manufacturing method of forming the laminate 10 by laminating the battery cells 11 on the cover shown in FIG. 3, the space between the laminate 10 and the inner surface of the housing 20 can be reduced. Therefore, the power storage device 1 can be miniaturized and the energy density can be improved.

[0048] The embodiments disclosed this time should be considered as illustrative in all respects and not restrictive. The scope of this invention is shown not by the above description but by the claims, and it is intended that all meanings equivalent to the claims and all modifications within the scope are included.

Explanation of Reference Numerals

[0049] 1 Power storage device, 10 Laminate, 11 Battery cell, 12 Electrode body, 13 Connection part, 14 Main terminal, 15 Gasket, 20 Housing, 21 Bottom wall, 22 Side wall, 23 Top wall, 24 Ceiling surface, 25 Welded part, 26 Inner wall surface, 31, 32 Insulating sheet, 33 Bent part, 34 Protrusion, 35, 36 Exposed area.

Claims

1. A laminate in which a plurality of battery cells are laminated, a housing that houses the laminate, and an insulating sheet disposed between the ceiling surface of the housing and the laminate, wherein the ceiling surface has an exposed area not covered by the insulating sheet, the insulating sheet has a convex portion protruding downward, the convex portion is disposed between the laminate and the exposed area in plan view, and the convex portion has a shape extending in a rib shape, the housing has a side wall constituting a side surface of the housing and a top wall constituting an upper surface of the housing, and a lower surface of the top wall constitutes the ceiling surface, the housing further has a welded portion where the side wall and the top wall are welded, a power storage device, wherein the exposed area is provided at a peripheral portion of the top wall.

2. The insulating sheet has a bent portion where a periphery of the insulating sheet is bent, The power storage device according to claim 1, wherein the bent portion forms the convex portion.

3. The laminate has a connection portion that electrically connects two adjacent battery cells in a lamination direction to each other, The power storage device according to claim 1 or claim 2, wherein the convex portion is disposed between the connection portion and the exposed area in plan view.

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