Electricity storage device

Abstract

The invention provides a power storage device capable of reducing cracks of an insulating resin member generated by heating and cooling at a joint part of a current collector terminal and a housing member with the integrally formed insulating resin member, and improving water tightness (sealing performance) in the housing. A power storage device is provided with: a case cover having a terminal insertion hole; a collector terminal having a hole insertion portion inserted into the terminal insertion hole in the front-back direction of the housing, and an external connection portion provided continuously from the hole insertion portion and disposed parallel to the housing cover on the front surface side of the housing; and an insulating resin member integrally formed with the collector terminal and the case cover so as to connect the hole insertion part and the external connection part to the hole outer edge part and the hole peripheral part of the terminal insertion hole. The insulating resin member is provided with a rear surface-side insulating resin that connects the rear surface of the external connection part, the hole outer edge part, the hole peripheral part, and the hole insertion part, and a hollow part having an open rear surface side is formed in the rear surface-side insulating resin part.

Description

Technical Field

[0001] The disclosed technology relates to an electric storage device. Background Art

[0002] For example, Patent Document 1 discloses a sealed storage battery in which an insulating resin member is integrally molded (insert-molded) with a current collector terminal and a case member so as to fill a space between the current collector terminal and a terminal insertion hole of the case member.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2021-86813 Summary of the invention

[0006] Problems to be solved by the invention

[0007] However, the insulating resin member is usually composed of resin as the main component, and therefore, the linear expansion coefficient of the insulating resin member is different from that of the metal collector terminal and the case member. Therefore, there is a problem that when the completed sealed storage battery is subjected to a hot and cold endurance test of repeated cooling and heating cycles at about -40°C to +60°C, tensile stress is accumulated at the joint between the insulating resin member and the collector terminal or the case member, cracks are generated in the relatively weak insulating resin member, and the sealing performance in the case member is reduced.

[0008] The disclosed technology is made in view of this problem and provides a power storage device capable of reducing cracks in the insulating resin member generated by heating and cooling at the joint between the current collecting terminal and the case member and the integrally formed insulating resin member, thereby improving the sealing performance in the case member.

[0009] Solutions to Solve Problems

[0010] (1)One aspect of the disclosed technology for solving the above problems is an electrical storage device, wherein the electrical storage device includes: a housing member having a terminal insertion hole; a current collecting terminal having a hole insertion portion and an external connection portion, the hole insertion portion being inserted into the terminal insertion hole along the front-back direction of the housing, the external connection portion being continuously provided from the hole insertion portion and disposed parallel to the housing member on the housing surface side; and an insulating resin member integrally formed with the current collecting terminal and the housing member so as to connect the hole insertion portion and the external connection portion to the hole outer edge portion and the peripheral portion of the terminal insertion hole, the insulating resin member having a back-side insulating resin portion that connects the back surface of the external connection portion, the hole outer edge portion, the peripheral portion, and the hole insertion portion, and a hollow portion (Japanese: meat removal portion) that is open on the back side is formed in the back-side insulating resin portion.

[0011] (2)The electrical storage device according to (1) may be an electrical storage device in which the back-side insulating resin portion has an insulating resin layer with a thickness of 200 μm or more between the back surface of the external connection portion and the hollow bottom surface on the housing surface side of the hollow portion.

[0012] (3)The electrical storage device according to (1) or (2) may be an electrical storage device in which the hollow portion is formed in a rectangular shape when viewed from the housing back side, and the back-side insulating resin portion includes a hollow side wall surface formed by the hollow portion and a connecting rib that connects the opposing hollow side wall surfaces among the hollow side wall surfaces. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is an exploded perspective view of one aspect (this embodiment) of the electrical storage device of the present embodiment.

[0014] Figure 2 is Figure 1 a partial perspective view of the portion A shown in FIG. viewed obliquely from the housing back side.

[0015] Figure 3 is Figure 1 a cross-sectional view taken along line B-B of the electrical storage device shown in FIG.

[0016] Figure 4 is Figure 1 a cross-sectional view taken along line B-B of a comparative example of the electrical storage device shown in FIG.

[0017] Figure 5 is Figure 1 a partial perspective view of the portion A in a modified example of the electrical storage device shown in FIG. viewed obliquely from the housing back side. DETAILED DESCRIPTION OF THE INVENTION

[0018] <Description of the present electrical storage device>

[0019] Hereinafter, one mode (this embodiment) of the electric storage device 10 according to the embodiment of the above-disclosed technology will be described in detail with reference to the drawings. Figure 1 An exploded perspective view showing one mode (this example) of the power storage device according to the present embodiment. Figure 2 express Figure 1 The A portion shown is a partial perspective view when viewed obliquely from the rear side of the housing. Figure 3 express Figure 1 BB cross-sectional view shown.

[0020] like Figure 1 to Figure 3 As shown, one mode (this embodiment) of the power storage device 10 of the embodiment of the disclosed technology includes a case cover (an example of a "case member" of the present disclosure) 4, a collector terminal 3, and an insulating resin member 5 integrally formed (insert-molded) with the collector terminal 3 and the case cover 4. The case cover 4 has a pair of terminal insertion holes 41 at both ends in the longitudinal direction. The collector terminal 3 has a hole insertion portion 31 and an external connection portion 32, and the hole insertion portion 31 is arranged along the case front-back direction (in the case back direction). Figure 3 The external connection portion 32 is continuously provided from the hole insertion portion 31 and is arranged parallel to the housing cover 4 on the housing surface side CF. The external connection portion 32 is formed to be rectangular in a plan view from the housing surface side CF (the upper side in the figure). The terminal insertion hole 41 is formed to be large enough to allow the hole insertion portion 31 and the external connection portion 32 to be inserted. The hole insertion portion 31 and the external connection portion 32 are bent at a right angle.

[0021] In addition, the insulating resin member 5 is integrally molded (insert-molded) with the collector terminal 3 and the case cover 4 in such a manner that the hole insertion portion 31 and the external connection portion 32 are connected to the hole outer edge portion 411 and the hole surrounding portion 412 of the terminal insertion hole 41. The hole insertion portion 31 of the collector terminal 3 and the hole surrounding portion 412 of the case cover 4 are formed with, for example, annular roughened surfaces 311 and 413 with an arithmetic mean roughness of 30 to 500 nm, and constitute a joint portion (sealing portion) SR with the insulating resin member 5. In addition, the insulating resin member 5 includes a back side insulating resin portion 51 that connects the back side 321 of the external connection portion 32, the hole outer edge portion 411, the hole surrounding portion 412, and the hole insertion portion 31. In addition, the insulating resin member 5 includes an outer peripheral side insulating resin portion 53 that surrounds the side edge portion 322 of the external connection portion 32 over the entire circumference on the case surface side CF of the case cover 4. The volume of the outer circumferential side insulating resin portion 53 is smaller than the volume of the back side insulating resin portion 51. In addition, the external connection portion surface 323 of the external connection portion 32 located on the case surface side CF and the outer circumferential side insulating resin portion surface 531 of the outer circumferential side insulating resin portion 53 located on the case surface side CF are formed on the same plane. In addition, at a position of the outer circumferential side insulating resin portion 53 close to the case center, a resin injection portion (gate portion) 54 of the insulating resin member 5 is formed protruding toward the case center.

[0022] Here, the present power storage device 10 comprises: an electrode body 1; a case body 2 having an opening 21 and accommodating the electrode body 1; a collector terminal 3 electrically connected to the electrode body 1; a case cover 4 having a terminal insertion hole 41, holding the collector terminal 3 inserted in the terminal insertion hole 41 and holding the electrode body 1 via the collector terminal 3, and sealing the opening 21 of the case body 2; and an insulating resin member 5 integrally formed (insert-molded) with the collector terminal 3 and the case cover 4 in a manner that connects the hole insertion portion 31 and the external connection portion 32 of the collector terminal 3 with the hole outer edge portion 411 and the hole surrounding portion 412 of the terminal insertion hole 41. However, the present power storage device 10 may not necessarily be limited to the above structure. For example, the terminal insertion hole 41 may also be formed in the case body 2 (an example of the "case member" of the present disclosure). In the present embodiment, the case of the power storage device 10 is constituted by the case body 2 and the case cover 4.

[0023] In addition, the present power storage device 10 refers to all power storage devices that can extract electric energy, such as primary batteries, secondary batteries, double-layer capacitors, etc. In addition, the electrode body 1 is a known electrode body formed by stacking a positive electrode body having an active material layer of a positive electrode and a negative electrode body having an active material layer of a negative electrode through a separator. The shell body 2 is a bottomed cylindrical body with an opening 21 formed at the upper end, for example, made of aluminum or an aluminum alloy. The collector terminal 3 is composed of a positive collector terminal 3a connected to the positive side of the electrode body 1 and a negative collector terminal 3b connected to the negative side of the electrode body 1. The positive collector terminal 3a is, for example, made of aluminum or an aluminum alloy, and the negative collector terminal 3b is, for example, made of copper or a copper alloy. The shell cover 4 is, for example, made of aluminum or an aluminum alloy and is formed into a flat plate-shaped cover. The shell cover 4 is formed with a terminal insertion hole 41 for inserting the collector terminal 3, a known safety valve 42, and an injection hole 43 for injecting electrolyte.

[0024] In addition, the insulating resin component 5 has a thermoplastic resin material NJ having heat resistance, formability, insulation, sealing, resistance to electrolyte, etc. Here, the thermoplastic resin material NJ uses PPS resin (polyphenylene sulfide resin), but it is not limited to this. In addition, the insulating resin component 5 may also contain reinforcing components such as glass fibers or elastomers in the thermoplastic resin material NJ. When the insulating resin component 5 contains 50% by weight of glass fibers in the PPS resin matrix, the linear expansion coefficient of the resin material in the flow direction during molding is 0.97×10 －5 / ℃, and the linear expansion coefficient in the direction perpendicular to the flow direction is 4.13×10 －5 / °C, and the average (randomly oriented) linear expansion coefficient (that is, the average linear expansion coefficient when the insulating resin member 5 contains randomly oriented glass fibers) is 2.54×10 －5 / °C. In contrast, the linear expansion coefficient of aluminum forming the case cover 4 and the positive electrode current collector terminal 3a is 2.4×10 －5 / °C, and the linear expansion coefficient of the copper forming the negative electrode current collector terminal 3b is 1.8×10 －5 / ℃.

[0025] As described above, the linear expansion coefficient of the insulating resin member 5 is different from that of the case cover 4 and the collector terminals 3 (3a, 3b). Therefore, when the electrical storage device 10 is subjected to a hot and cold endurance test, tensile stress is accumulated in the joint (sealing portion) SR between the insulating resin member 5 and the collector terminals 3 or the case cover 4, and cracks may occur in the relatively weak insulating resin member 5.

[0026] Therefore, in the present power storage device 10, if Figure 2 , Figure 3As shown, in order to reduce cracks generated in the joint (sealing portion) SR of the insulating resin member 5 due to thermal shrinkage, a hollow portion 52 opened on the back side CB (lower side in the figure) of the shell is formed in the back side insulating resin portion 51. In addition, an insulating resin layer 511 with a predetermined thickness t1 is provided between the back side 321 of the external connection portion 32 and the hollow bottom surface 521 of the hollow portion 52 located on the surface side CF of the shell. The depth t2 of the hollow portion 52 in the shell front-back direction is formed to be greater than the thickness t1 of the insulating resin layer 511. Through the hollow portion 52, the deformation resistance of the back side insulating resin portion 51 connecting the back side 321 of the external connection portion 32, the hole outer edge portion 411, the hole surrounding portion 412 and the hole insertion portion 31 during thermal shrinkage is reduced, thereby reducing the tensile stress P1 acting on the joint SR between the hole insertion portion 31 of the collector terminal 3 and the back side insulating resin portion 51. In addition, by having the insulating resin layer 511, water penetration from the outside through the hollow portion 52 can be avoided. As a result, cracks in the insulating resin member 5 can be reduced at the joint (sealing portion) SR between the insulating resin member 5 and the collector terminal 3 or the case cover 4, and the sealing inside the case consisting of the case cover 4 and the case body 2 can be improved. In addition, the thickness t1 of the insulating resin layer 511 is preferably 200 μm or more. This is because if the thickness t1 of the insulating resin layer 511 is 200 μm or more, it is possible to prevent fine particles of water from passing through the gaps between molecules of the insulating resin layer 511, and the watertightness of the insulating resin layer 511 can be ensured.

[0027] In contrast, Figure 4 express Figure 1 BB cross-sectional view of a comparative example of the power storage device shown. Figure 4 As shown, in the electric storage device 10C of the comparative example, the back side insulating resin portion 51C connecting the back side 321 of the external connection portion 32, the hole outer edge portion 411, the hole surrounding portion 412 and the hole insertion portion 31 is not formed. Figure 2 , Figure 3 The hollow portion 52 shown. The storage device 10C of the comparative example is the same as the storage device 10 of the present embodiment except for the hollow portion 52, and therefore, the same reference numerals are given. Therefore, when the storage device 10C of the comparative example is cooled to, for example, about -40°C, the case cover 4 and the external connection portion 32 of the collector terminal 3 that are about to shrink are resisted by the back side insulating resin portion 51C with a small amount of shrinkage, and therefore deform in a direction of warping into a convex shape toward the back side CB of the case of the back side insulating resin portion 51C. Therefore, the tensile stress P2 acting on the joint SR between the hole insertion portion 31 of the collector terminal 3 and the back side insulating resin portion 51C increases. As a result, cracks in the insulating resin member 5 increase at the joint (sealing portion) SR between the insulating resin member 5 and the collector terminal 3 or the case cover 4, and the sealing performance in the case is reduced.

[0028] Based on the above, the power storage device 10 of this embodiment can provide a power storage device that can reduce cracks in the insulating resin member 5 generated at the joint (sealing portion) SR between the collector terminal 3 and the case cover 4 and the insulating resin member 5 due to heating and cooling, thereby improving the sealing performance in the case.

[0029] <Modification>

[0030] The above detailed description of the present embodiment is only for illustration and does not limit the disclosed technology. Therefore, the disclosed technology can be variously improved and modified within the scope of its purpose. For example, Figure 2 , Figure 3 The hollow portion 52 shown is formed as a rectangular hollow body with the back side CB of the housing open, but it is not necessary to be limited to this. Figure 5 As shown in the figure, the following power storage device 10B may be provided: the hollow portion 52B is formed in a rectangular shape when viewed from the back side CB of the case, and the back side insulating resin portion 51 includes a hollow side wall surface 512 formed by the hollow portion 52 and a connecting rib 513 connecting the hollow side wall surfaces 512 facing each other in the hollow side wall surfaces 512. By providing the connecting rib 513 connecting the hollow side wall surfaces 512, the connecting force of the back side insulating resin portion 51 to connect the collector terminal 3 and the case cover 4 can be improved, and since the connecting rib 513 expands and contracts during heating and cooling, cracks in the insulating resin member 5 caused by heating and cooling can be reduced. In addition, the connecting rib 513 can be formed in a curved shape as shown in the figure, but can also be formed in a straight shape. In addition, the connecting ribs 513 can be provided as length direction connecting ribs 513a extending in the length direction of the shell cover 4 and width direction connecting ribs 513b extending in the width direction of the shell cover 4, but can also be only one of the length direction connecting ribs 513a and the width direction connecting ribs 513b.

[0031] Description of Reference Numerals

[0032] 3 current collecting terminal, 4 case cover, 5 insulating resin member, 10, 10B power storage device, 31 hole insertion portion, 32 external connection portion, 41 terminal insertion hole, 51 back side insulating resin portion, 52, 52B hollow portion, 411 hole outer edge portion, 412 hole surrounding portion, 512 side wall surface, 513 connecting rib.

Claims

1. An electric storage device, wherein: The power storage device comprises: a housing member having a terminal insertion hole; A collector terminal having a hole insertion portion and an external connection portion, wherein the hole insertion portion is inserted into the terminal insertion hole along the shell front-back direction of the shell member, and the external connection portion is continuously provided from the hole insertion portion and is arranged parallel to the shell member on the shell surface side of the shell member; and an insulating resin member formed integrally with the collector terminal and the case member in such a manner that the hole insertion portion and the external connection portion are connected to the hole outer edge portion and the hole periphery portion of the terminal insertion hole, The insulating resin member includes a back side insulating resin portion, the back side insulating resin portion connecting the back side of the external connection portion, the hole outer edge portion, the hole peripheral portion, and the hole insertion portion. The rear-side insulating resin portion has a hollow portion that is open on the rear side of the case member.

2. The power storage device according to claim 1, wherein The hollow portion has a hollow bottom surface located on the surface side of the shell, The back-side insulating resin portion includes an insulating resin layer having a thickness of 200 μm or more between the back surface of the external connecting portion and the hollow bottom surface of the hollow portion.

3. The power storage device according to claim 1 or 2, wherein: The hollow portion is formed in a rectangular shape when viewed from the back side of the housing. The back-side insulating resin portion includes a hollow side wall surface formed by the hollow portion and a connecting rib connecting the facing hollow side wall surfaces among the hollow side wall surfaces.

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