JP7399922B2 - battery - Google Patents

Description

The present invention relates to batteries.

BACKGROUND ART A battery such as a lithium ion secondary battery has a configuration in which, for example, an electrode body housed within a battery case and a terminal exposed outside the battery case are electrically connected. A battery with such a configuration generally includes an electrode body in which a positive electrode plate and a negative electrode plate face each other with a separator interposed therebetween, an exterior body having an opening and accommodating the electrode body, and a sealing body that seals the opening of the exterior body. The device includes a plate, and a terminal that is electrically connected to the electrode body inside the exterior body and extends from the sealing plate to the outside of the exterior body. The battery case of such a battery is constructed, for example, by welding a fitting portion where the exterior body and the sealing plate are fitted together. As the welding method, a laser welding method can be preferably employed.

By the way, in the above battery, the terminal (external terminal) extending from the sealing plate to the outside of the exterior body and the outer surface of the sealing plate can be separated and insulated by an external insulating member made of an insulating material. When laser welding is performed on a battery that has such an external insulating member, there is a risk that the external insulating member may be damaged or that a plume (smoky metal vapor) containing fine metal particles generated during welding may adhere to the external insulating member. If the insulation distance (for example, spatial distance) required for insulation is not ensured, poor insulation between the sealing plate and the external terminal may occur. Patent Document 1 discloses a battery that has such an external insulating member and has an exterior body and a sealing plate welded by laser irradiation, and has a space formed by the sealing plate and the external insulating member, and a Shielding gas is flowed so that the plume stably rises vertically from the battery case, preventing the high-temperature plume generated during laser welding from contacting the external insulation material, and insulating the sealing plate and external terminals. It is disclosed that defects are suppressed.

Japanese Patent Application Publication No. 2014-10887

However, if the flow rate of the shielding gas is small, the plume may come into contact with the external insulating member and the metal particles may adhere to it, making it impossible to ensure the insulation distance between the metal particles and the external terminal, resulting in insulation failure. There is. Furthermore, if the flow rate of the shielding gas is large, the shielding gas may make the liquid melted part unstable during laser welding, leading to welding defects. Therefore, according to the technique disclosed in Patent Document 1, it may be difficult to ensure stable insulation.

The present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a battery in which insulation is more suitably ensured by an external insulating member.

The battery disclosed herein includes an electrode body that is a power generation element, an exterior body having an opening and housing the electrode body therein, a sealing plate that seals the opening of the exterior body, and the electrode body. The device includes an external terminal that is electrically connected to the body and a portion of which extends outside the sealing plate, and an external insulating member that separates the external terminal from the outer surface of the sealing plate. The sealing plate is fitted to the exterior body, and the fitting portion of the sealing plate and the exterior body is welded by irradiating a laser from the outer surface of the sealing plate, and the external insulating member includes: The wall has a wall portion surrounding the external terminal, and a recessed portion formed on the external terminal side and an upper end portion higher in height from the sealing plate than the recessed portion are formed on the upper surface side of the wall portion. The recess is formed in at least a portion of the wall.
As described above, by having the recess on the external terminal side of the external insulating member, the recess is located below the side wall side of the external insulating member, making it difficult for the plume to come into contact with it during welding. By providing the concave portion on the external insulating terminal side, it is possible to prevent metal particles from adhering to the vicinity of the external terminal and causing insufficient insulation due to insufficient distance required for insulation. According to the external insulating member having such a configuration, a battery with suitable insulation properties can be realized.

In one aspect of the battery disclosed herein, the recess is formed at least in a region close to the fitting part over the entire circumference of the wall. According to this configuration, contact with the plume becomes more difficult during welding, so it is possible to provide a battery in which insulation is suitably ensured by the external insulating member.

In one embodiment of the battery disclosed herein, the recess has an inclined surface whose height from the sealing plate gradually decreases from the upper end toward the external terminal. According to this configuration, it is difficult for the plume to come into contact with the battery during welding, and metal particles are prevented from adhering to the vicinity of the external terminal, so that it is possible to provide a battery in which insulation properties are suitably ensured by the external insulating member. can.

In one aspect of the battery disclosed herein, the inclined surface is formed to be inclined at 30° or more and 70° or less with respect to the side wall of the wall portion. According to this configuration, it is possible to provide a battery in which insulation properties are more suitably ensured by the external insulating member.

In one aspect of the battery disclosed herein, the wall portion is formed such that a step is formed between the upper end portion and the recessed portion, and the upper end portion has a height approximately equal to that from the sealing plate. The height of the recessed portion from the sealing plate is approximately constant. By providing the recess on the external terminal side, metal fine particles are prevented from adhering to the vicinity of the external terminal, so it is possible to provide a battery in which insulation is suitably ensured by the external insulating member.

In one aspect of the battery disclosed herein, the wall portion is formed such that a step is formed between the upper end portion and the recessed portion, and the upper end portion has a height from the sealing plate as described above. The height of the recess is gradually decreased toward the recess, and the height of the recess from the sealing plate is approximately constant. Thereby, it is possible to provide a battery in which insulation is more suitably ensured by the external insulating member.

FIG. 1 is a perspective view schematically showing a battery according to an embodiment. FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. 1. FIG. FIG. 2 is a plan view schematically showing a positive external terminal and a positive external insulating member according to one embodiment. 3 is a partially enlarged sectional view schematically showing the vicinity of the positive electrode terminal in FIG. 2. FIG. 5 is a partially enlarged sectional view schematically showing an example of the vicinity of the positive electrode external insulating member of FIG. 4. FIG. 5 is a cross-sectional view schematically showing another example of the vicinity of the positive electrode external insulating member of FIG. 4. FIG. It is a perspective view which shows typically the electrode body group attached to the sealing board. It is a perspective view which shows typically the wound electrode body to which the positive electrode 2nd current collection part and the negative electrode 2nd current collection part were attached. FIG. 3 is a schematic diagram showing the configuration of a wound electrode body. FIG. 2 is a schematic vertical cross-sectional view taken along line XX in FIG. 1. FIG. 2 is a schematic cross-sectional view taken along the line XI-XI in FIG. 1. FIG. FIG. 7 is a partially enlarged sectional view schematically showing an example of the vicinity of the positive electrode external insulating member in the second embodiment. FIG. 7 is a cross-sectional view schematically showing another example of the vicinity of the positive electrode external insulating member in the second embodiment. FIG. 7 is a cross-sectional view schematically showing an example of the vicinity of a positive electrode external insulating member in a third embodiment.

Hereinafter, some preferred embodiments of the technology disclosed herein will be described with reference to the drawings. Further, matters other than those specifically mentioned in this specification that are necessary for carrying out the present invention (for example, the general structure and manufacturing process of a battery that do not characterize the present invention) are well known in the field. This can be understood as a matter of design by a person skilled in the art based on the prior art. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the field. In this specification, the notation "A to B" indicating a range includes the meanings of "A to B" as well as "preferably larger than A" and "preferably smaller than B."

Note that in this specification, the term "battery" refers to all electricity storage devices that can extract electrical energy, and is a concept that includes primary batteries and secondary batteries. In addition, in this specification, "secondary battery" is a term that refers to all electricity storage devices that can be repeatedly charged and discharged, and includes so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and This concept includes capacitors (physical batteries) such as double layer capacitors.

1. First Embodiment FIG. 1 is a perspective view of a battery 100. FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. FIG. 3 is a plan view schematically showing the positive external terminal 34 and the positive external insulating member 92. As shown in FIG. FIG. 4 is an enlarged cross-sectional view schematically showing the vicinity of the positive external terminal 34 in FIG. 2. As shown in FIG. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the symbols X, Y, and Z in the drawings represent the battery 100. The short side direction, the long side direction orthogonal to the short side direction, and the vertical direction are respectively expressed. However, these directions are merely for convenience of explanation, and do not limit the installation form of the battery 100 in any way.

As shown in FIG. 2, the battery 100 includes a battery case 10, an electrode assembly 20, a positive external terminal 34, a positive external insulating member 92, a negative external terminal 44, and a negative external insulating member 94. ing. Although not shown, the battery 100 here further includes an electrolyte. Battery 100 is a lithium ion secondary battery here.

The battery case 10 is a housing that houses the electrode assembly 20. The battery case 10 has a rectangular parallelepiped shape (square) that is flat and has a bottom. The material of the battery case 10 may be the same as that conventionally used and is not particularly limited. The battery case 10 is preferably made of metal, and more preferably made of, for example, aluminum, aluminum alloy, iron, iron alloy, or the like. As shown in FIG. 2, the battery case 10 includes an exterior body 12 having an opening 12h, and a sealing plate (lid) 14 that closes the opening 12h.

As shown in FIG. 1, the exterior body 12 includes a bottom wall 12a, a pair of long side walls 12b extending from the bottom wall 12a and facing each other, and a pair of short side walls 12c extending from the bottom wall 12a and facing each other. We are prepared. The bottom wall 12a has a substantially rectangular shape. The bottom wall 12a faces the opening 12h. The area of the short side wall 12c is smaller than the area of the long side wall 12b.

The sealing plate 14 is attached to the exterior body 12 so as to close the opening 12h of the exterior body 12. The sealing plate 14 faces the bottom wall 12a of the exterior body 12. The sealing plate 14 has a substantially rectangular shape in plan view. As shown in FIG. 2, the sealing plate 14 is provided with a liquid injection hole 15, a gas discharge valve 17, and two terminal extraction holes 18 and 19. The terminal extraction holes 18 and 19 are formed at both ends of the sealing plate 14 in the long side direction Y, respectively. The terminal extraction holes 18 and 19 penetrate the sealing plate 14 in the vertical direction Z. The terminal extraction holes 18 and 19 each have an inner diameter large enough to allow the positive electrode terminal 30 and the negative electrode terminal 40 to be inserted therethrough before being attached to the sealing plate 14, respectively. The liquid injection hole 15 is for pouring an electrolytic solution after the sealing plate 14 is assembled to the exterior body 12. The liquid injection hole 15 is sealed by a sealing member 16. The gas exhaust valve 17 is configured to break when the pressure inside the battery case 10 exceeds a predetermined value, and discharge the gas inside the battery case 10 to the outside.

As mentioned above, the battery 100 includes an electrolyte. The electrolyte may be the same as the conventional one and is not particularly limited. The electrolytic solution is, for example, a non-aqueous electrolytic solution containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent includes carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as _LiPF6 . However, the electrolytic solution may be in a solid state (solid electrolyte) and may be integrated with the electrode body group 20.

The positive electrode terminal 30 and the negative electrode terminal 40 are each fixed to the sealing plate 14. The positive electrode terminal 30 is arranged on one side of the sealing plate 14 in the long side direction Y (on the left side in FIGS. 1 and 2). The negative electrode terminal 40 is arranged on the other side of the sealing plate 14 in the long side direction Y (on the right side in FIGS. 1 and 2). As shown in FIG. 1, the positive electrode terminal 30 and the negative electrode terminal 40 are exposed on the outer surface of the sealing plate 14. As shown in FIG. 2, the positive electrode terminal 30 and the negative electrode terminal 40 extend from the inside of the sealing plate 14 to the outside by passing through the terminal extraction holes 18 and 19.

As shown in FIG. 2, the positive electrode terminal 30 is electrically connected to the positive electrode plate 22 (see FIG. 9) of the electrode assembly group 20 through the positive electrode current collector 50 inside the exterior body 12. The positive electrode terminal 30 is insulated from the sealing plate 14 by a positive electrode insulating member 70 and a gasket 90. The positive electrode terminal 30 is preferably made of metal, and more preferably made of aluminum or an aluminum alloy, for example. The positive electrode terminal 30 may be configured by joining and integrating two conductive members. Further, as shown in FIG. 1, the positive electrode terminal 30 has a plate-shaped positive electrode external conductive member 32 attached thereto. The positive external conductive member 32 is a member to which a bus bar is attached when electrically connecting the plurality of batteries 100 to each other. The positive external conductive member 32 is preferably made of metal, and more preferably made of aluminum or an aluminum alloy, for example. In this specification, the positive electrode terminal 30 and the positive external conductive member 32 are collectively referred to as a positive external terminal 34. The positive external terminal 34 is an example of the external terminal of the battery disclosed herein.

As shown in FIGS. 3 and 4, the positive external terminal 34 is separated from and electrically insulated from the outer surface 14A of the sealing plate 14 by a positive external insulating member 92. The positive external insulating member 92 is provided so as to surround the positive external terminal 34 . The positive electrode external insulating member 92 is an example of an external insulating member of the battery disclosed herein.

As shown in FIG. 2, the negative electrode terminal 40 is electrically connected to the negative electrode plate 24 (see FIG. 9) of the electrode assembly group 20 through the negative electrode current collector 60 inside the exterior body 12. The negative electrode terminal 40 is insulated from the sealing plate 14 by a negative electrode insulating member 80 and a gasket 90. The negative electrode terminal 40 is preferably made of metal, and more preferably made of copper or a copper alloy, for example. The negative electrode terminal 40 may be configured by joining two electrically conductive members and integrating them. For example, the portion connected to the negative electrode current collector 60 may be made of copper or a copper alloy, and the portion exposed on the outer surface of the sealing plate 14 may be made of aluminum or an aluminum alloy. Moreover, as shown in FIG. 1, the negative electrode terminal 40 is attached with a plate-shaped negative electrode external conductive member 42. The negative external conductive member 42 is a member to which a bus bar is attached when electrically connecting the plurality of batteries 100 to each other, and is preferably made of the same material as the positive external conductive member 32. In this specification, the negative electrode terminal 40 and the negative electrode external conductive member 42 are collectively referred to as a negative electrode external terminal 44. The negative external terminal 44 is an example of the external terminal of the battery disclosed herein.

Like the positive external terminal 34, the negative external terminal 44 is separated from and electrically insulated from the outer surface 14A of the sealing plate 14 by the negative external insulating member 94. The negative external insulating member 94 is provided to surround the negative external terminal 44 . The negative electrode external insulating member 94 is an example of an external insulating member of the battery disclosed herein.

In the battery case 10, the opening 12h of the exterior body 12 and the sealing plate 14 are fitted, and the fitting portion 11 between the outer edge of the outer surface 14A of the sealing plate 14 and the exterior body 12 around the opening 12h is laser welded. By doing so, the sealing plate 14 is fixed to the exterior body 12. The above laser welding is performed by irradiating laser light from the outer surface 14A side of the sealing plate 14, as shown in FIG. Thereby, the battery case 10 is hermetically sealed (sealed). When laser welding the fitting portion 11 between the exterior body 12 and the sealing plate 14, a high temperature plume is generated. A plume is mainly vaporized metal rising up like smoke, and the plume contains fine metal particles. In particular, in the battery case 10 used when manufacturing a large battery for the purpose of increasing capacity, etc., the thickness of the exterior body 12 and the sealing plate 14 tends to be increased in order to increase the rigidity. When laser welding the exterior body 12 and the sealing plate 14, a high output power is required, and the plume generated during welding tends to spread over a wide range. Since the portion to which the fine metal particles contained in the plume are attached has conductivity, it is difficult to ensure suitable insulation only by providing an external insulating member. Therefore, the external insulating member disclosed herein is configured so that even if metal fine particles adhere to the external insulating member, insulation is ensured by having an appropriate insulation distance (space distance and creepage distance). ing. Therefore, a highly safe battery is realized.

Here, the "insulation distance" refers to the shortest distance for insulating conductive objects from each other without separating them with an insulating material. Typical examples of insulation distance include space distance and creepage distance, and by appropriately securing both, conductive objects can be insulated from each other. "Spatial distance" refers to the shortest distance through space between conductive objects. Moreover, "creepage distance" refers to the shortest distance along the surface of an insulator between conductive objects. For example, if a recess exists between conductive objects, the creepage distance will be longer than the spatial distance. However, if the width of the recess is 1 mm or less, it is ignored and there is no effect of extending the creepage distance.

5 is a diagram schematically showing an example of the vicinity of the positive electrode external insulating member 92 of FIG. 4, and FIG. 6 is a diagram schematically showing another example of the vicinity of the positive electrode external insulating member 92 of FIG. 4. be. Here, the battery disclosed herein will be described in detail using the positive external terminal 34 and the positive external insulating member 92 as an example, but the negative external terminal 44 and the negative external insulating member 94 can also have a similar configuration.

As shown in FIGS. 3 to 6, the positive external insulating member 92 has a wall portion 92a surrounding the positive external terminal 34 and a flat portion 92b. The upper surface side of the wall portion 92a has a recess 96 formed on the positive electrode external terminal 34 side, and an upper end portion 98 that is higher in height from the sealing plate 14 than the recess 96. The recess 96 is formed in at least a portion of the wall 92a. The recess 96 may be formed all around the wall 92a.

The position where the recess 96 is provided may be changed as appropriate in consideration of the position of the external terminal in the battery case 10 and the distance from the fitting part 11. In one preferred embodiment, the recess 96 is preferably formed at least in a region close to the fitting portion 11 around the entire circumference of the wall portion 92a. Here, the region near the fitting part 11 refers to the side facing the fitting part 11 among the four sides forming the entire circumference of the wall part 92a of the rectangular positive electrode external insulating member 92. More specifically, as shown in FIG. 3, a pair of long sides 92A and 92C facing the fitting part 11 and a short side 92B facing the fitting part 11 and close to the fitting part 11 are included. It can be done. Therefore, as shown in FIG. 4, a recess 96 is formed on the short side 92B facing and close to the fitting part 11, and a recess 96 is formed on the short side 92D far from the fitting part 11. It doesn't have to be. That is, the region of the wall portion 92a close to the fitting portion 11 refers not only to the region closest to the fitting portion 11 but also to the region relatively close to the fitting portion 11.
Note that the shape of the positive electrode external insulating member 92 does not need to be rectangular as shown in the figure, and may be circular. Even in this case, the position where the recess is formed may be changed as appropriate, taking into account the position of the external terminal in the battery case 10 and the distance from the fitting part 11. For example, the recess may be formed in at least a portion of the wall, and is preferably formed in at least a region close to the fitting portion 11 around the entire circumference of the wall.

As described above, when laser welding the fitting portion 11 between the exterior body 12 and the sealing plate 14, a high-temperature plume is generated, and metal particles contained in the plume may adhere to the external insulating member. Even if metal fine particles adhere to the upper end 98 of the positive electrode external insulating member 92, which is higher in height from the sealing plate 14 than the recess 96, no metal is attached to the upper surface of the recess 96 located on the positive electrode external terminal 34 side. Fine particles do not adhere, and an appropriate insulation distance is ensured between the attachment area of the metal fine particles and the positive electrode external terminal 34. Thereby, the insulation of the positive electrode external terminal 34 is ensured, and a highly safe battery can be provided.

The width (length in the Y direction) T1 of the wall portion 92a is set to a width that will not be damaged by heat when laser welding the fitting portion 11. From the viewpoint of ensuring a suitable insulation distance, it is preferable that the width T1 of the wall portion 92a is 1 mm or more. The height (length in the Z direction) H1 of the wall portion 92a is not particularly limited, and may be set to the same height as a conventionally known external insulating member.

As shown in FIGS. 5 and 6, the recess 96 has an inclined surface 96a whose height from the sealing plate 14 gradually decreases from the upper end 98 toward the positive external terminal 34 side in cross-sectional view. The maximum depth h1 of the recessed portion 96 (maximum height difference with respect to the upper end portion 98) is not particularly limited, but may be, for example, 1 mm. The width w1 of the recess 96 is configured such that even if metal particles adhere to the upper end portion 98, an appropriate insulation distance is secured between the area where the metal particles are attached and the positive electrode external terminal 34. . It is preferable that the width w1 of the recess 96 is, for example, 1 mm or more. Here, the spatial distance between the positive electrode external terminal 34 made of metal and the adhering region of the conductive metal fine particles matches the width w1 of the recess 96. Since the creepage distance between the positive electrode external terminal 34 and the adhesion region of the metal fine particles is longer than the spatial distance when the width w1 of the recess 96 is 1 mm or more, more suitable insulation is ensured and high safety is achieved. Batteries can be provided.

The ratio (w1/T1) of the width w1 of the recessed portion 96 to the width T1 of the wall portion 92a is preferably 0.4 or more, more preferably 0.6 or more, and preferably 0.9 or more. More preferably, it is particularly preferably 1. That is, as shown in FIG. 6, the width T1 of the wall portion 92a and the width w1 of the recessed portion 96 may be the same width (length). In the case of the configuration shown in FIG. 6, almost no metal particles are attached to the upper end portion 98, and an appropriate distance can be secured in both the spatial distance and the creepage distance, and the positive electrode external terminal can be more preferably connected. 34 can be insulated.

It is preferable that the inclined surface 96a be formed to be inclined with respect to the side wall 92e of the wall portion 92a at an angle that does not contact the plume and that allows the wall portion 92a to maintain a predetermined strength. From this point of view, the inclined surface 96a is preferably formed to be inclined at an angle θ of 30° or more and 70° or less with respect to the side wall 92e of the wall portion 92a, and is preferably formed at an angle θ of 40° or more and 60° or less. More preferably, it is formed so as to.

As the constituent materials of the positive electrode external insulating member 92 and the negative electrode external insulating member 94, various insulating resin materials can be appropriately selected and used. For example, polyolefin resins such as polypropylene (PP) and polyethylene (PE), fluorinated resins such as tetrafluoroethylene-perfluoroalkyl vinyl ether resin (PFA), polyphenylene sulfide (PPS), polyamide, polyacetal (POM), and methacrylic resins. etc. The type of resin contained in the resin material constituting the external insulating member can be identified by applying general analysis techniques such as infrared (IR) spectrum analysis and pyrolysis gas chromatography in combination as necessary. . When the external insulating member includes a plurality of resins, the blending ratio of those resins can be determined from the above analysis results and the specific gravity of the external insulating member.

FIG. 7 is a perspective view schematically showing the electrode assembly group 20 attached to the sealing plate 14. As shown in FIG. The electrode body group 20 here includes three wound electrode bodies 20a, 20b, and 20c. However, the number of wound electrode bodies disposed inside one exterior body 12 is not particularly limited, and may be two or more (plurality) or one. The electrode body group 20 is disposed inside the exterior body 12 while being covered with an electrode body holder 29 (see FIG. 10) made of a resin sheet.

FIG. 8 is a perspective view schematically showing the wound electrode body 20a. FIG. 9 is a schematic diagram showing the configuration of the wound electrode body 20a. FIG. 10 is a schematic vertical cross-sectional view taken along line XX in FIG. FIG. 11 is a schematic cross-sectional view taken along line XI-XI in FIG. In addition, although the wound electrode body 20a will be explained in detail below as an example, the same structure can be applied to the wound electrode bodies 20b and 20c.

The wound electrode body 20a is a power generation element and includes a positive electrode plate 22, a negative electrode plate 24, and a separator 26. The wound electrode body 20a is constructed by laminating a band-shaped positive electrode plate 22 and a band-shaped negative electrode plate 24 with two band-shaped separators 26 in between, and winding them around a winding axis WL. There is. The wound electrode body 20a has a flat shape. The wound electrode body 20a is arranged inside the exterior body 12 with the winding axis WL substantially parallel to the long side direction Y. As shown in FIG. 10, the wound electrode body 20a connects a pair of curved parts (R parts) 20r facing the bottom wall 12a and the sealing plate 14 of the exterior body 12, and connects the pair of curved parts 20r. It has a flat portion 20f facing the 12 long side walls 12b. The flat portion 20f extends along the long side wall 12b.

The separator 26 is a member that insulates the positive electrode active material layer 22a of the positive electrode plate 22 and the negative electrode active material layer 24a of the negative electrode plate 24. The separator 26 here constitutes the outer surface of the wound electrode body 20a. As the separator 26, a porous sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable, for example. It is preferable that the separator 26 has a base material portion made of a porous sheet made of resin, and a heat resistance layer (HRL) formed on at least one surface of the base material portion. The heat-resistant layer is a layer containing an inorganic filler. As the inorganic filler, for example, alumina, boehmite, aluminum hydroxide, titania, etc. can be used.

As shown in FIG. 9, the positive electrode plate 22 includes a positive electrode core 22c, and a positive electrode active material layer 22a and a positive electrode protective layer 22p fixed on at least one surface of the positive electrode core 22c. However, the positive electrode protective layer 22p is not essential and can be omitted in other embodiments. The positive electrode core 22c is strip-shaped. The positive electrode core 22c is made of a conductive metal such as aluminum, aluminum alloy, nickel, stainless steel, or the like. The positive electrode core body 22c is a metal foil, specifically an aluminum foil here. Further, the average thickness of the positive electrode core 22c is not particularly limited. For example, the thickness is preferably 2 μm to 30 μm, more preferably 2 μm to 20 μm, and even more preferably 5 μm to 15 μm.

A plurality of positive electrode tabs 22t are provided at one end (left end in FIG. 9) of the positive electrode core body 22c in the long side direction Y. The plurality of positive electrode tabs 22t protrude to one side (left side in FIG. 9) in the long side direction Y. The plurality of positive electrode tabs 22t protrude beyond the separator 26 in the long side direction Y. The plurality of positive electrode tabs 22t are provided at intervals (intermittently) along the longitudinal direction of the positive electrode plate 22. However, the positive electrode tab 22t may be provided at the other end in the long side direction Y (the right end in FIG. 9), or may be provided at both ends in the long side direction Y, respectively. The positive electrode tab 22t is a part of the positive electrode core 22c, and is made of metal foil (aluminum foil). In at least a portion of the positive electrode tab 22t, the positive electrode active material layer 22a and the positive electrode protection layer 22p are not formed, and the positive electrode core body 22c is exposed.

As shown in FIG. 9, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction of the strip-shaped positive electrode core body 22c. The positive electrode active material layer 22a includes a positive electrode active material (for example, a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide) that can reversibly insert and release charge carriers. When the entire solid content of the positive electrode active material layer 22a is 100% by mass, the positive electrode active material may occupy approximately 80% by mass or more, typically 90% by mass or more, for example, 95% by mass or more. The positive electrode active material layer 22a may contain arbitrary components other than the positive electrode active material, such as a conductive material, a binder, and various additive components. As the conductive material, for example, a carbon material such as acetylene black (AB) can be used. As the binder, for example, polyvinylidene fluoride (PVdF) can be used.

As shown in FIG. 9, the positive electrode protective layer 22p is provided at the boundary between the positive electrode core 22c and the positive electrode active material layer 22a in the long side direction Y. The positive electrode protective layer 22p is provided here at one end in the long side direction Y (the left end in FIG. 9) of the positive electrode core 22c. However, the positive electrode protective layer 22p may be provided at both ends in the long side direction Y. The positive electrode protective layer 22p is provided in a strip shape along the positive electrode active material layer 22a. The positive electrode protective layer 22p contains an inorganic filler (eg, alumina). When the entire solid content of the positive electrode protective layer 22p is 100% by mass, the inorganic filler may account for approximately 50% by mass or more, typically 70% by mass or more, for example 80% by mass or more. The positive electrode protective layer 22p may contain arbitrary components other than the inorganic filler, such as a conductive material, a binder, and various additive components. The conductive material and binder may be the same as those exemplified as being included in the positive electrode active material layer 22a.

As shown in FIG. 9, the negative electrode plate 24 includes a negative electrode core 24c and a negative electrode active material layer 24a fixed on at least one surface of the negative electrode core 24c. The negative electrode core 24c is strip-shaped. The negative electrode core 24c is made of a conductive metal such as copper, copper alloy, nickel, stainless steel, or the like. The negative electrode core body 24c is a metal foil, specifically a copper foil here.

A plurality of negative electrode tabs 24t are provided at one end (right end in FIG. 9) of the negative electrode core body 24c in the long side direction Y. The plurality of negative electrode tabs 24t protrude beyond the separator 26 in the long side direction Y. The plurality of negative electrode tabs 24t protrude beyond the separator 26 in the long side direction Y. The plurality of negative electrode tabs 24t are provided at intervals (intermittently) along the longitudinal direction of the negative electrode plate 24. The negative electrode tab 24t protrudes to one side in the long side direction Y (the right side in FIG. 9). However, the negative electrode tab 24t may be provided at the other end in the long side direction Y (the left end in FIG. 9), or may be provided at both ends in the long side direction Y, respectively. The negative electrode tab 24t is a part of the negative electrode core 24c, and is made of metal foil (copper foil). A negative electrode active material layer 24a is formed in a part of the negative electrode tab 24t. The negative electrode active material layer 24a is not formed on at least a portion of the negative electrode tab 24t, and the negative electrode core body 24c is exposed.

As shown in FIG. 9, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of the strip-shaped negative electrode core body 24c. The negative electrode active material layer 24a includes a negative electrode active material (for example, a carbon material such as graphite) that can reversibly occlude and release charge carriers. When the entire solid content of the negative electrode active material layer 24a is 100% by mass, the negative electrode active material may account for approximately 80% by mass or more, typically 90% by mass or more, for example, 95% by mass or more. The negative electrode active material layer 24a may contain arbitrary components other than the negative electrode active material, such as a binder, a dispersant, various additive components, and the like. As the binder, for example, rubber such as styrene butadiene rubber (SBR) can be used. As a dispersant, for example, cellulose such as carboxymethyl cellulose (CMC) can be used.

As shown in FIG. 11, the plurality of positive electrode tabs 22t are stacked at one end in the long side direction Y (left end in FIG. 11) to form a positive electrode tab group 23. The plurality of positive electrode tabs 22t are bent and curved so that their outer ends are aligned. Thereby, the accommodation capacity in the battery case 10 can be improved and the battery 100 can be made smaller. The positive electrode tab group 23 is electrically connected to the positive electrode terminal 30 via the positive electrode current collector 50 . As shown in FIGS. 2 and 7, the positive electrode current collector 50 includes a positive electrode first current collector 51, which is a plate-shaped conductive member that extends along the inner surface of the sealing plate 14, and a positive electrode first current collector 51 that extends along the vertical direction Z. It includes a plurality of positive electrode second current collectors 52 that are elongated plate-shaped conductive members. The lower end 30c of the positive electrode terminal 30 extends toward the inside of the battery case 10 through the terminal extraction hole 18 of the sealing plate 14, and is connected to the positive electrode first current collector 51 (see FIG. 2). On the other hand, as shown in FIGS. 7 and 8, the positive electrode second current collector 52 is connected to the positive electrode tab group 23 of each of the plurality of wound electrode bodies 20a, 20b, and 20c. As shown in FIGS. 7 and 11, the positive electrode tab group 23 of the wound electrode bodies 20a, 20b, 20c is connected to the positive electrode second current collector 52 and one side surface 20e of the wound electrode bodies 20a, 20b, 20c. are bent so that they are facing each other. As a result, the upper end portion of the second positive current collector 52 and the first positive current collector 51 are electrically connected. The first positive current collector 51 and the second positive current collector 52 may be made of the same metal as the positive electrode core 22c, for example, a conductive metal such as aluminum, aluminum alloy, nickel, or stainless steel.

As shown in FIG. 11, the plurality of negative electrode tabs 24t are stacked at one end in the long side direction Y (the right end in FIG. 11) to form a negative electrode tab group 25. The negative electrode tab group 25 is provided at a position symmetrical to the positive electrode tab group 23 in the long side direction Y. The plurality of negative electrode tabs 24t are bent and curved so that their outer ends are aligned. Thereby, the accommodation capacity in the battery case 10 can be improved and the battery 100 can be made smaller. The negative electrode tab group 25 is electrically connected to the negative electrode terminal 40 via the negative electrode current collector 60 . The configuration of the negative electrode current collector 60 may be the same as the configuration of the positive electrode current collector 50. Specifically, as shown in FIGS. 2 and 7, the negative electrode current collector 60 has a negative electrode first current collector 61, which is a plate-shaped conductive member extending along the inner surface of the sealing plate 14, and It includes a plurality of negative electrode second current collectors 62 that are plate-shaped conductive members extending along the Z direction. The lower end portion 40c of the negative electrode terminal 40 extends toward the inside of the battery case 10 through the terminal extraction hole 19 of the sealing plate 14, and is connected to the negative electrode first current collector 61 (see FIG. 2). On the other hand, as shown in FIGS. 7 and 8, the negative electrode second current collector 62 is connected to the negative electrode tab group 25 of each of the plurality of wound electrode bodies 20a, 20b, and 20c. The first negative current collector 61 and the second negative current collector 62 may be made of the same metal as the negative electrode core 24c, for example, a conductive metal such as copper, copper alloy, nickel, or stainless steel.

As shown in FIG. 2, a positive electrode insulating member 70 is disposed between the positive electrode first current collector 51 and the inner surface of the sealing plate 14. The positive electrode insulating member 70 is a member that insulates the sealing plate 14 and the positive electrode first current collector 51. The positive electrode insulating member 70 is made of a resin material that has resistance to the electrolytic solution used, has electrical insulation properties, and is elastically deformable, such as polyolefin resin such as polypropylene (PP), tetrafluorocarbon It is preferably made of a fluorinated resin such as ethylene-perfluoroalkyl vinyl ether resin (PFA), polyphenylene sulfide (PPS), or the like.

The positive electrode insulating member 70 includes a plate-shaped base portion 70 a interposed between the positive electrode first current collector 51 and the inner surface of the sealing plate 14 . This can prevent the positive electrode first current collector 51 from being electrically connected to the sealing plate 14 . Furthermore, the positive electrode insulating member 70 includes a protrusion 70b that protrudes from the inner surface of the sealing plate 14 toward the wound electrode bodies 20a, 20b, and 20c that constitute the electrode body group 20 (see FIGS. 4 and 10). ). This restricts the movement of the wound electrode bodies 20a, 20b, 20c in the vertical direction Z, and prevents the wound electrode bodies 20a, 20b, 20c from coming into direct contact with the sealing plate 14. The number of protrusions 70b is the same as the number of wound electrode bodies 20a, 20b, and 20c that constitute the electrode body group 20 here. However, the number of protrusions 70b may be different from the number of electrode bodies constituting the electrode body group 20, and may be one, for example.

As shown in FIG. 2, the negative electrode insulating member 80 is arranged symmetrically with the positive electrode insulating member 70 with respect to the center CL of the electrode body group 20 in the long side direction Y. The configuration of the negative electrode insulating member 80 may be the same as that of the positive electrode insulating member 70. Like the positive electrode insulating member 70, the negative electrode insulating member 80 includes a base portion 80a disposed between the sealing plate 14 and the negative electrode first current collector 61, and a plurality of protrusions 80b.

Although the battery 100 can be used for various purposes, it can be suitably used, for example, as a power source (driving power source) for a motor mounted on a vehicle such as a passenger car or a truck. The type of vehicle is not particularly limited, and examples thereof include a plug-in hybrid vehicle (PHV), a hybrid vehicle (HV), an electric vehicle (EV), and the like. The battery 100 can be suitably used for constructing an assembled battery.

2. Other Embodiments The first embodiment described above is just one example of the battery disclosed herein. The technology disclosed herein can be implemented in various other forms. Other embodiments of the technology disclosed herein will be described below.

<Second embodiment>
In the first embodiment described above, the positive electrode external insulating member 92 has a recess 96 and an upper end 98 on the upper surface side of the wall portion 92a, and the height of the recess 96 from the sealing plate 14 gradually decreases toward the external terminal side. It had an inclined surface 96a. However, the technology disclosed herein is not limited to the first embodiment. For example, the wall portion may be formed to have a step between the upper end portion and the recessed portion, and the heights of the upper end portion and the recessed portion from the sealing plate may be formed to be substantially constant.

12 and 13 are schematic cross-sectional views of the vicinity of the positive external terminal 34 of the battery according to the second embodiment. The battery according to the second embodiment includes a positive external insulating member 292 that separates the positive external terminal 34 from the outer surface of the sealing plate 14 . The positive external insulating member 292 has a wall portion 292a surrounding the positive external terminal 34 and a flat portion 292b. The wall portion 292a has a recess 296 formed on the positive external terminal 34 side, and an upper end portion 298 that is higher in height from the sealing plate 14 than the recess 296. The wall portion 292a of the second embodiment is formed to have a step between the recessed portion 296 and the upper end portion 298, and the heights of the recessed portion 296 and the upper end portion 298 from the sealing plate 14 are approximately constant.
In the second embodiment, it is sufficient that the recess 296 is formed on the side of the positive electrode external terminal 34 and that a step is formed between the upper end 298 and the recess 296, so as shown in FIG. There may be a region (hereinafter also referred to as "convex section 299") whose height from the sealing plate 14 is higher than the concave section 296 on the side closer to the positive electrode external terminal 34 than the concave section 296 .

The width (length in the Y direction) T2 of the wall portion 292a is set to a width that will not damage the fitting portion 11 due to the heat generated when laser welding it, similarly to the first embodiment described above. From the viewpoint of ensuring a suitable insulation distance, it is preferable that the width T2 of the wall portion 292a is 1 mm or more. The upper limit of the width T2 of the wall portion 292a is not particularly limited. Further, the height (length in the Z direction) H2 of the wall portion 292a is not particularly limited, and may be set to the same height as a conventionally known external insulating member. In addition, when the convex part 299 exists, the height of the convex part 299 from the sealing plate 14 is not particularly limited as long as it is higher than the concave part 296 and lower than the maximum height H2 of the wall part 292a. .

The recess 296 may be configured so that the positive external terminal 34 is suitably insulated. The width w2 of the recess 296 is set so that even if metal particles contained in the plume adhere to the upper end portion 298, an appropriate insulation distance is secured between the area where the metal particles are attached and the positive electrode external terminal 34. The diameter is 1 mm or more. Note that when the convex portion 299 is present, the width of the concave portion 296 is not particularly limited as long as the width w2 can ensure the above-mentioned width. By ensuring the width w2 of the recess 296 to be 1 mm or more, the insulation of the positive external terminal 34 is suitably ensured.

The depth h2 of the recess 296 is not particularly limited. Further, the depth h2 of the recess 296 is a ratio (h2/H2) to the maximum height H2 of the wall portion 292a, and is preferably set to, for example, about 0.2 or more and 0.9 or less. If the recess 296 has such a height h2, adhesion of metal fine particles is prevented, and the insulation of the positive electrode external terminal 34 is suitably ensured.
Note that the battery according to the second embodiment may have the same configuration as the battery 100 according to the first embodiment except for what is described above.

<Third embodiment>
In the first embodiment described above, the positive electrode external insulating member 92 has a recess 96 and an upper end 98 on the upper surface side of the wall 92a, and the height of the recess 96 from the sealing plate 14 gradually decreases toward the external terminal side. It had an inclined surface 96a. However, the technology disclosed herein is not limited to the first embodiment. For example, the wall is formed so that there is a step between the upper end and the recess, the height of the upper end from the sealing plate gradually decreases toward the recess, and the height of the recess from the sealing plate is approximately constant. may be formed.

FIG. 14 is a schematic cross-sectional view of the vicinity of the positive external terminal 34 of the battery according to the third embodiment. In the battery according to the third embodiment, as shown in FIG. 14, the positive external insulating member 392 has a wall portion 392a surrounding the positive external terminal 34 and a flat portion 392b. The upper surface side of the wall portion 392a has a recess 396 formed on the positive electrode external terminal 34 side, and an upper end portion 398 that is higher in height from the sealing plate 14 than the recess 396. In the third embodiment, a step is formed between the upper end 398 and the recess 396, and the height of the upper end 398 from the sealing plate 14 gradually decreases toward the recess 396. 396 has a substantially constant height from the sealing plate 14.

The width (length in the Y direction) T3 of the wall portion 392a is set to a width that will not be damaged by heat when laser welding the fitting portion 11, similarly to the first embodiment described above. From the viewpoint of ensuring a suitable insulation distance, the width T3 of the wall portion 392a is preferably 1 mm or more. Further, the height (length in the Z direction) H3 of the wall portion 392a is not particularly limited, and may be set to the same height as a conventionally known external insulating member.

As shown in FIG. 14, the upper end portion 398 has an inclined surface whose height from the sealing plate 14 gradually decreases from the upper end portion 298 toward the recess 396 side in cross-sectional view. The inclined surface is preferably formed to be inclined at an angle θ of 30° or more and 70° or less with respect to the side wall 392e of the wall portion 392a, and is formed to be inclined at an angle θ of 40° or more and 60° or less. It is more preferable that Thereby, the wall portion 392a can maintain a predetermined strength without coming into contact with the plume.

In the third embodiment, the upper end portion 398 also has an inclined surface, which has the effect of suppressing plume contact during welding. Therefore, when the total width of the upper end portion 398 and the width w3 of the recessed portion 396 (that is, the width T3 of the wall portion 392a) is 1 mm or more, suitable insulation can be ensured. More preferably, the width w3 of the recess 396 is 1 mm or more. Furthermore, the depth h3 of the recess 396 is not particularly limited. By having the upper end portion 398 having an inclined surface and the recessed portion 396 having the above-described shape, an external insulating member that appropriately insulates the external terminal is realized.
Note that the battery according to the third embodiment may have the same configuration as the battery 100 according to the first embodiment except for what is described above.

Although several embodiments of the present invention have been described above, the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the field. The technology described in the claims includes various modifications and changes to the embodiments exemplified above. For example, it is also possible to replace a part of the embodiment described above with other modifications, and it is also possible to add other modifications to the embodiment described above. Also, if the technical feature is not described as essential, it can be deleted as appropriate.

10 Battery case 11 Fitting part 12 Exterior body 14 Sealing plate (lid body)
18 Terminal extraction hole 19 Terminal extraction hole 20 Electrode body group 20a, 20b, 20c Wound electrode body 22 Positive electrode plate 24 Negative electrode plate 26 Separator 30 Positive electrode terminal 32 Positive electrode outer conductive member 34 Positive electrode external terminal 40 Negative electrode terminal 42 Negative electrode outer conductive member 44 Negative external terminal 50 Positive current collector 60 Negative current collector 70 Positive insulating member 80 Negative insulating member 90 Gasket 92 Positive external insulating member 92a Wall 92b Flat portion 92e Side wall 94 Negative external insulating member 96 Recess 96a Slanted surface 98 Upper end 100 Battery 292 Positive electrode external insulation member 292a Wall portion 296 Recessed portion 298 Upper end portion 299 Convex portion 392 Positive electrode external insulation member 392a Wall portion 392e Side wall 396 Recessed portion 398 Upper end portion

Claims (6)

An electrode body which is a power generation element,
an exterior body having an opening and housing the electrode body therein;
a sealing plate that seals the opening of the exterior body;
an external terminal electrically connected to the electrode body, a part of which extends outside the sealing plate;
an external insulating member separating the external terminal from the outer surface of the sealing plate;
A battery comprising:
The sealing plate is fitted to the exterior body, and the fitting portion of the sealing plate and the exterior body is welded by laser irradiation from the outer surface side of the sealing plate,
The external insulating member has a wall portion surrounding the external terminal,
A recess formed on the external terminal side and an upper end portion having a higher height from the sealing plate than the recess are formed on the upper surface side of the wall portion,
The battery, wherein the recess is formed in at least a portion of the wall. The battery according to claim 1, wherein the recess is formed at least in a region close to the fitting part on the entire circumference of the wall. The battery according to claim 1 or 2, wherein the recess has an inclined surface whose height from the sealing plate gradually decreases from the upper end toward the external terminal. The battery according to claim 3, wherein the inclined surface is formed to be inclined at an angle of 30 degrees or more and 70 degrees or less with respect to a side wall of the wall portion. The wall portion is formed so that a step is formed between the upper end portion and the recessed portion,
The upper end portion has a substantially constant height from the sealing plate,
The battery according to claim 1 or 2, wherein the recess has a substantially constant height from the sealing plate. The wall portion is formed so that a step is formed between the upper end portion and the recessed portion,
The height of the upper end portion from the sealing plate gradually decreases toward the recess,
The battery according to claim 1 or 2, wherein the recess has a substantially constant height from the sealing plate.

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