JP7702932B2 - Electricity storage device and method for manufacturing the same - Google Patents

Description

This disclosure relates to an electricity storage device and a method for manufacturing an electricity storage device.

In recent years, power storage devices such as lithium-ion secondary batteries have been suitably used as portable power sources for personal computers, mobile terminals, and the like, and as power sources for driving vehicles such as electric vehicles (BEVs), hybrid vehicles (HEVs), and plug-in hybrid vehicles (PHEVs). Conventionally, a power storage device has been known that has an exterior body having a bottom, a side wall extending from the periphery of the bottom, and an opening surrounded by the side wall, and a sealing plate that seals the opening, and is provided with a melted and solidified part at the fitting part between the exterior body and the sealing plate. For example, Patent Document 1 discloses a manufacturing method characterized by offsetting the spot center of a laser beam to the inside of the fitting part. In addition, Patent Document 2 discloses a technology characterized by partially thickening the thickness of the upper part of the side wall of the case (exterior body) so that it protrudes toward the inside of the case for the purpose of stabilizing the shape of the bead (melted and solidified part).

Japanese Patent Application Publication No. 8-315788 JP 2016-66583 A

However, in conventional electricity storage devices, the molten and solidified portion protrudes outward from the exterior body, causing fluctuations in the dimensions of the electricity storage device. As electricity storage devices become more widespread, stable dimensional accuracy is required, as well as stable welding quality and high reliability, including high energy. Therefore, the inventor believes that it is desirable to suppress the molten and solidified portion of the electricity storage device from protruding outward from the exterior body without changing the welding conditions or the inner dimensions of the exterior body.

The technology disclosed herein has been developed in light of the above circumstances, and its purpose is to provide an electricity storage device and a method for manufacturing an electricity storage device that have reliable dimensional accuracy by suppressing the molten and solidified portion from protruding outside the exterior body.

The technology disclosed herein relates to an electric storage device that includes an electrode body having an electrode, a bottom, a sidewall extending from the periphery of the bottom, and an opening surrounded by the sidewall, and that includes an exterior body that houses the electrode body, a sealing plate that seals the opening, and an annular molten solidified portion formed at the fitting portion between the opening of the exterior body and the sealing plate. The electric storage device disclosed herein has an extrusion prevention layer on at least a portion of the periphery of the opening of the exterior body that prevents the molten solidified portion from being formed outside the exterior body.

With this configuration, when the molten solidified portion is formed, the protrusion prevention layer prevents the molten solidified portion from protruding out of the exterior body. This provides an electricity storage device with reliable dimensional accuracy.

FIG. 1 is a perspective view that illustrates a power storage device according to an embodiment. FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. FIG. 3 is a top view that typically illustrates the exterior body and the sealing plate. FIG. 4 is a vertical cross-sectional view showing the vicinity of the molten solidified portion according to one embodiment. FIG. 5 is a flow diagram showing a method for manufacturing an electricity storage device according to one embodiment. FIG. 6 is a vertical cross-sectional view that illustrates a laser welding process according to an embodiment. FIG. 7 is a view corresponding to FIG. 4 according to the first modified example. FIG. 8 is a view corresponding to FIG. 4 according to a second modified example. FIG. 9 is a vertical cross-sectional view showing the vicinity of a molten solidified portion according to a conventional example.

Below, the embodiments of the technology disclosed herein will be described with reference to the drawings. Matters not mentioned in this specification but necessary for implementing the technology disclosed herein can be understood as design matters of a person skilled in the art based on the conventional technology in the field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the field. In addition, in the following drawings, the same reference numerals are used to describe members and parts that perform the same function. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each figure do not reflect the actual dimensional relationships. In addition, the numerical range expressed as "A to B" in this specification includes A and B, and also includes the meanings of "preferably larger than A" and "preferably smaller than B". Furthermore, in this specification, "main" refers to a component that accounts for 70% or more by weight of the total components.

In this specification, the term "energy storage device" refers to a device that can be charged and discharged. Energy storage devices include batteries generally referred to as lithium ion batteries and lithium secondary batteries, as well as lithium polymer batteries and lithium ion capacitors. A secondary battery generally refers to a battery that can be repeatedly charged and discharged by the movement of charge carriers between the positive and negative electrodes. Here, a lithium ion secondary battery is given as an example of one form of energy storage device.

<Electricity storage device 100>
FIG. 1 is a perspective view showing a schematic view of the electric storage device 100 according to the first embodiment. FIG. 2 is a schematic vertical cross-sectional view taken along the line II-II in FIG. 1. FIG. 3 is a top view showing a schematic view of the exterior body 12 and the sealing plate 18. In FIG. 2 and FIG. 3, the exterior body 12 and the sealing plate 18 are before being welded (before the molten solidified portion 50 is formed). In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom. In addition, the symbol X in the drawings indicates the short side direction (also referred to as the thickness direction) of the electric storage device 100, the symbol Y indicates the long side direction of the electric storage device 100, and the symbol Z indicates the up-down direction (also referred to as the height direction) of the electric storage device 100. However, these are merely directions for convenience of description and do not limit the installation form of the electric storage device 100 in any way.

As shown in Figures 1 and 2, the electricity storage device 100 includes a case 1, an electrode body 20, a positive electrode terminal 6, a negative electrode terminal 8, a positive electrode current collector 35, and a negative electrode current collector 45. Although not shown, the electricity storage device 100 further includes an electrolyte. The electricity storage device 100 is characterized by including an extrusion prevention layer 60 disclosed herein, and other configurations may be the same as those of conventional devices. The electricity storage device 100 is preferably a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery.

The case 1 is a housing that houses the electrode body 20. As shown in Figs. 1 and 2, the case 1 includes an exterior body 12 having an opening 15, and a sealing plate 18 that seals the opening 15. The exterior body 12 and the sealing plate 18 have sizes according to the number of electrode bodies 20 (one or more) that are housed, their sizes, etc. The case 1 is preferably made of metal, and more preferably made of aluminum or an aluminum alloy mainly made of aluminum. Here, the case 1 is made of aluminum. As shown in Fig. 1, the case 1 has a flat, bottomed, approximately rectangular parallelepiped shape (square). However, the shape of the case 1 is not limited to this, and may be, for example, cylindrical.

1 and 2, the exterior body 12 is a container with a bottom and a substantially rectangular parallelepiped shape having an opening 15 on one side (here, the top surface). As shown in FIG. 1, the exterior body 12 has a substantially rectangular bottom 12d having a pair of short sides and a pair of long sides, a pair of short side walls 12a, 12b that extend upward from the short sides of the bottom 12d and face each other, and a pair of long side walls 12e, 12f that extend upward from the long sides of the bottom 12d and face each other. In this specification, the term "substantially rectangular" includes not only a perfect rectangular shape (rectangular shape), but also a shape in which the corners connecting the long and short sides of the rectangle are rounded or a shape with a notch at the corner. The short side walls 12a, 12b and the long side walls 12e, 12f are examples of the "side walls" disclosed herein.

An opening 15 surrounded by a pair of short side walls 12a, 12b and a pair of long side walls 12e, 12f is formed on one side of the exterior body 12. As shown in FIG. 2, the bottom 12d faces the opening 15. As shown in FIG. 2, the exterior body 12 has an upper end surface 13. The upper end surface 13 has a pair of short side portions 13a, 13b and a pair of long side portions 13e, 13f (see FIG. 3). The short side portions 13a, 13b are the upper edges of the short side walls 12a, 12b. The long side portions 13e, 13f are the upper edges of the long side walls 12e, 12f. Furthermore, the exterior body 12 has a peripheral portion 16 where the outer surfaces of the short side walls 12a, 12b and the long side walls 12e, 12f intersect with the upper end surface 13.

As shown in Figs. 1 and 2, the sealing plate 18 is a member that seals the opening 15 of the exterior body 12. Here, the sealing plate 18 is a plate-shaped member that is substantially rectangular in plan view. As shown in Fig. 2, the sealing plate 18 is provided with a liquid injection hole 71, a gas exhaust valve 73, and terminal withdrawal holes 74, 75. The sealing plate 18 faces the bottom 12d of the exterior body 12. As will be described in detail later, the case 1 is integrated by fitting the opening 15 of the exterior body 12 with the sealing plate 18 and welding the fitting portion 11. This hermetically seals (closes) the case 1.

The liquid injection hole 71 is a through hole for injecting electrolyte into the case 1 after the sealing plate 18 is attached to the exterior body 12. Here, the liquid injection hole 71 is sealed by a sealing member 72 after the electrolyte is injected. The gas exhaust valve 73 is a thin-walled portion configured to break when the pressure inside the case 1 reaches or exceeds a predetermined value, thereby discharging gas inside the case 1 to the outside.

As the electrolyte, any electrolyte that has been publicly known and is used can be used without any particular limitation. As an example, a non-aqueous electrolyte in which a supporting salt (electrolyte salt) is dissolved in a non-aqueous solvent (organic solvent) is preferably used. As an example of the non-aqueous solvent, a carbonate-based solvent such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, etc. can be mentioned. As an example of the supporting salt, a fluorine-containing lithium salt such as _LiPF6 can be mentioned. The electrolyte may contain an additive as necessary.

The positive terminal 6 is attached to one end of the sealing plate 18 in the long side direction Y (the left end in FIG. 2). The negative terminal 8 is attached to the other end of the sealing plate 18 in the long side direction Y (the right end in FIG. 2). As shown in FIG. 2, the positive terminal 6 and the negative terminal 8 are inserted through the terminal pull-out holes 74, 75 and exposed on the outer surface of the sealing plate 18. As shown in FIG. 2, the positive terminal 6 is electrically connected to the positive electrode 3 of the electrode body 20 through the positive electrode current collector 35 inside the outer casing 12. The negative terminal 8 is electrically connected to the negative electrode 4 of the electrode body 20 through the negative electrode current collector 45 inside the outer casing 12. The positive terminal 6 and the negative terminal 8 are insulated from the sealing plate 18 by the gasket 76 and the insulator 78. A current interruption device (CID) may also be installed between the positive terminal 6 and the positive current collector 35 or between the negative terminal 8 and the negative current collector 45.

The positive electrode terminal 6 is preferably made of a metal, and more preferably made of, for example, aluminum or an aluminum alloy. The negative electrode terminal 8 is preferably made of a metal, and more preferably made of, for example, copper or a copper alloy. The negative electrode terminal 8 may be formed by joining two conductive members together. For example, the portion connected to the negative electrode current collecting member 45 may be made of copper or a copper alloy, and the portion exposed on the outer surface of the sealing plate 18 may be made of aluminum or an aluminum alloy.

The gasket 76 and the insulator 78 may be made of a material with excellent chemical resistance and weather resistance. The gasket 76 and the insulator 78 may be made of a resin material that is electrically insulating and elastically deformable, such as a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA), polyphenylene sulfide resin (PPS), or aliphatic polyamide.

Here, the positive electrode terminal 6 is electrically connected to a plate-shaped positive electrode external conductive member 36 on the outside of the case 1. Similarly, the negative electrode terminal 8 is electrically connected to a plate-shaped negative electrode external conductive member 46 on the outside of the case 1. The positive electrode external conductive member 36 and the negative electrode external conductive member 46 are connected to other electricity storage devices and external equipment via external connection members such as bus bars. The positive electrode external conductive member 36 and the negative electrode external conductive member 46 are preferably made of a metal with excellent conductivity such as aluminum, an aluminum alloy, copper, or a copper alloy. However, the positive electrode external conductive member 36 and the negative electrode external conductive member 46 are not essential and may be omitted in other embodiments.

The electrode body 20 may be the same as in the past, and is not particularly limited. As shown in FIG. 2, the electrode body 20 has a positive electrode 3 and a negative electrode 4. Here, the electrode body 20 is a flat wound electrode body in which a strip-shaped positive electrode 3 and a strip-shaped negative electrode 4 are stacked in an insulated state via a strip-shaped separator 7, and wound around a winding axis. However, the electrode body 20 may be a laminated electrode body in which a square-shaped (typically rectangular) positive electrode 3 and a square-shaped (typically rectangular) negative electrode 4 are stacked in an insulated state. In addition, the number of electrode bodies 20 arranged inside one exterior body 12 is not particularly limited, and may be two or more (multiple). The positive electrode 3 and the negative electrode 4 are an example of an "electrode" in the technology disclosed herein.

As shown in FIG. 2, the positive electrode 3 has a positive electrode current collector 30 and a positive electrode active material layer 31 fixed onto the positive electrode current collector 30. The positive electrode current collector 30 is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode active material layer 31 is a layer containing a positive electrode active material (e.g., a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide) that can reversibly store and release charge carriers.

The negative electrode 4 has a negative electrode current collector 40 and a negative electrode active material layer 41 fixed onto the negative electrode current collector 40. The negative electrode current collector 40 is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The negative electrode active material layer 41 is a layer containing a negative electrode active material (e.g., a carbon material such as graphite) that can reversibly store and release charge carriers.

The separator 7 is a member that insulates the positive electrode active material layer 31 of the positive electrode 3 from the negative electrode active material layer 41 of the negative electrode 4. As the separator 7, for example, a porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable. In addition, a heat resistance layer (HRL) containing an inorganic filler may be provided on the surface of the separator 7.

2, at the left end of the long side direction Y of the electrode body 20, a part of the positive electrode collector 30 (positive electrode collector exposed part) on which the positive electrode active material layer 31 is not formed protrudes from the laminated part. A positive electrode collector member 35 is attached to the positive electrode collector exposed part. The positive electrode collector member 35 may be made of the same metal material as the positive electrode collector 30, for example, a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. In addition, at the right end of the long side direction Y of the electrode body 20, a part of the negative electrode collector 40 (negative electrode collector exposed part) on which the negative electrode active material layer 41 is not formed protrudes from the laminated part. A negative electrode collector member 45 is attached to the negative electrode collector exposed part. The material (metal type) of the negative electrode collector member 45 may be different from that of the positive electrode collector member 35. The negative electrode current collector 45 may be made of the same metal as the negative electrode current collector 40, such as a conductive metal such as copper, a copper alloy, nickel, or stainless steel.

The energy storage device 100 is constructed by fitting the exterior body 12 and the sealing plate 18 together and welding the fitting portion 11. Here, the sealing plate 18 and the exterior body 12 (upper end surface 13) are flush in plan view. Specifically, as shown in FIG. 3, the outer peripheral surface of the sealing plate 18 and the inner surface of the exterior body 12 (opening 15) are arranged (fitted) to face each other at the fitting portion 11. Then, by laser welding the fitting portion 11 all around, a ring-shaped molten solidification portion 50 is formed and the sealing plate 18 and the exterior body 12 are joined (see FIGS. 4 and 9).

9 is a vertical cross-sectional view showing the vicinity of the molten solidified portion 50 according to the conventional example. When the above welding is performed, as shown in FIG. 9, a part of the sealing plate 18 and the exterior body 12 (shown in phantom lines) melts, and the molten part solidifies to form the molten solidified portion 50. The shape of the molten solidified portion 50 is determined, for example, by the flow of the molten metal and the influence of the surface tension. In detail, the molten solidified portion 50 is formed by solidifying in a raised shape due to the surface tension of the molten metal. Therefore, as shown in FIG. 9, there is a risk that a part of the molten solidified portion 50 protrudes (protrudes) outward from the exterior body 12. Due to the protrusion of the molten solidified portion 50, the size of the electric storage device 100 (case 1) varies in the long side direction Y and the short side direction X. In this specification, "formed (protrudes) outward from the exterior body" means that at least a part of the molten solidified portion 50 protrudes in the long side direction Y or the short side direction X from the exterior body 12. Protruding at least a portion of the molten solidified portion 50 in the vertical Z direction is not included in the term "protruding outward."

The power storage device 100 disclosed herein was created in consideration of the above-mentioned problems, and is characterized by having an extrusion prevention layer 60. FIG. 4 is a vertical cross-sectional view showing the vicinity of the molten solidified portion 50 according to one embodiment. FIG. 4 is a view corresponding to FIG. 9 showing a conventional example. For convenience of explanation, in FIG. 4, the exterior body 12 and the sealing plate 18 before the molten solidified portion 50 is formed (before laser irradiation) are shown by virtual lines.

In the technology disclosed herein, the energy storage device 100 includes an extrusion prevention layer 60 on at least a portion of the periphery of the opening 15. The extrusion prevention layer 60 has a higher melting point than the molten solidified portion 50. As shown in FIG. 4, the extrusion prevention layer 60 is formed on the outer surface of the short side wall 12a of the exterior body 12. The upper end (U side) of the extrusion prevention layer 60 is disposed so as to reach the periphery 16. In this specification, the "periphery of the opening" refers to a portion of the outer surfaces of the short side walls 12a, 12b and long side walls 12e, 12f of the exterior body 12, and a portion of the upper end surface 13.

As described above, when constructing the electric storage device 100 in this embodiment, the fitting portion 11 between the exterior body 12 and the sealing plate 18 is irradiated with a laser L (see FIG. 6), and a portion of the exterior body 12 and the sealing plate 18 melts (see FIG. 4). When the molten solidified portion 50 is formed from the molten portion, a portion of the molten solidified portion 50 tends to be formed (protrude) outside the exterior body 12 due to the surface tension of the molten portion, etc. On the other hand, the melting point of the protrusion prevention layer 60 is higher than the melting point of the molten solidified portion 50. As a result, the protrusion prevention layer 60 has the role of suppressing the molten solidified portion 50 from protruding outward from the exterior body 12 (in FIG. 4, in the long side direction Y). Therefore, it is possible to prevent a portion of the molten solidified portion 50 from protruding outward from the exterior body 12.

The material of the extrusion prevention layer 60 may be appropriately selected according to the material (melting point) of the case 1 (exterior body 12 and sealing plate 18), the irradiation intensity of the laser, etc. For example, if the case 1 is made of aluminum or an aluminum alloy, the melting point of the extrusion prevention layer 60 may be about 800°C or higher, preferably about 850°C or higher, although this is not limited thereto. For example, the extrusion prevention layer 60 may be made of aluminum oxide (e.g., alumina, boehmite, bayerite, etc.), ceramic, electroless nickel plating, electroless nickel-ceramic plating, diamond-like carbon (DLC) coating, intrinsic carbon film (ICF) coating, cemented carbide thermal spraying, cemented carbide thermal spraying (WC), iron-based amorphous thermal spraying, etc., and preferably aluminum oxide, ceramic, electroless nickel plating, diamond-like carbon (DLC) coating, intrinsic carbon film (ICF) coating, etc., and more preferably aluminum oxide, electroless nickel plating.

The thickness of the extrusion prevention layer 60 is preferably 0.1 μm or more, more preferably 1.0 μm or more, from the viewpoint of exerting the effect of suppressing the extrusion of the molten solidified portion 50. On the other hand, from the viewpoint of the dimensional accuracy of the exterior body 12, it is preferably 100 μm or less, more preferably 50 μm or less. In addition, the height of the extrusion prevention layer 60 as viewed from the thickness direction (vertical direction Z) of the sealing plate 18 can be appropriately adjusted depending on the laser strength during laser welding and the material (melting point) of the case 1. The height of the extrusion prevention layer is preferably 0.8 mm or more, more preferably 0.9 mm or more, from the viewpoint of exerting the effect of suppressing the extrusion of the molten solidified portion 50.

Here, as shown in FIG. 3, the exterior body 12 has R sections 12g, 12h, 12i, and 12j provided between the short side walls 12a, 12b and the long side walls 12e, 12f. Here, an extrusion prevention layer 60 is also arranged on the R sections 12g, 12h, 12i, and 12j of the exterior body 12. Even when such a configuration is adopted, the effect of suppressing the extrusion of the molten solidified portion 50 outward from the exterior body 12 can be achieved. However, such a configuration is not essential and can be omitted.

Here, the extrusion prevention layer 60 is disposed around the entire periphery of the opening 15. However, this is not limited, and the extrusion prevention layer 60 does not necessarily have to be disposed around the entire periphery. For example, the extrusion prevention layer 60 may be disposed only on the short side walls 12a and 12b of the exterior body 12. With this configuration, the extrusion in the long side direction Y from the exterior body 12 is suppressed with respect to the molten solidified portion 50. This makes it possible to suitably suppress the dimensional deviation of the electric storage device 100 caused by the molten solidified portion 50 in the long side direction Y. In addition, the extrusion prevention layer 60 may be disposed only on the long side walls 12e and 12f of the exterior body 12. With this configuration, the extrusion in the long side direction Y from the exterior body 12 is suppressed with respect to the molten solidified portion 50. This makes it possible to suitably suppress the dimensional deviation of the electric storage device 100 caused by the molten solidified portion 50 in the short side direction X.

<Method of Manufacturing Electricity Storage Device 100>
The structure of the electricity storage device 100 according to the present embodiment has been described above. Meanwhile, as another aspect of the technology disclosed herein, a method for manufacturing the electricity storage device 100 is provided. FIG. 5 is a flow diagram showing a method for manufacturing the electricity storage device 100 according to an embodiment. The method for manufacturing the electricity storage device 100 is characterized by performing a prevention layer forming step S10. The electricity storage device 100 disclosed herein can be manufactured by a manufacturing method including a prevention layer forming step S10, a sealing plate fitting step S20, and a laser welding step S30. In addition to the above steps, the method for manufacturing the electricity storage device 100 disclosed herein may further include other steps at any stage, and the other manufacturing processes may be the same as conventional ones.

(Prevention layer forming step S10)
In the prevention layer forming step S10, an extrusion prevention layer 60 is formed on at least a part of the periphery of the opening 15 of the exterior body 12. The treatment that can be used to form the extrusion prevention layer 60 in the prevention layer forming step is not particularly limited, but examples include aluminum oxide film treatments such as anodizing, boehmite treatment, or bayerite treatment, ceramic coating treatments such as ceramic spraying, glass coating treatments, DLC (Diamond-like Carbon) coating treatments, intrinsic carbon film (ICF) coating treatments, and electroless nickel plating treatments. When the exterior body 12 is made of aluminum or an aluminum alloy, the prevention layer forming step S10 can preferably employ anodizing. By performing anodizing, an aluminum oxide film having a high melting point (about 2000° C.) can be formed as the extrusion prevention layer 60.

The method of anodizing may be the same as that of the conventionally known process. For example, first, masking is applied to the parts of the exterior body 12 where the extrusion prevention layer 60 is not to be formed. Here, masking is applied to the inner surface of the opening 15 and the upper end surface 13. Next, the periphery of the opening 15 of the exterior body 12 is immersed in an anodizing solution, and aluminum anodizing is performed. Thereafter, the masked part is peeled off to form the extrusion prevention layer 60. The thickness of the extrusion prevention layer 60 can be adjusted by controlling the anodizing solution, temperature, voltage, processing time, etc. Also, the formation area of the extrusion prevention layer 60 can be adjusted, for example, by the masked parts of the exterior body 12 and the immersion depth of the anodizing solution for the exterior body 12.

The anodizing solution can be any solution commonly used in anodizing, without any particular limitations. Examples include sulfuric acid, ammonium sulfate, sodium hydrogen sulfate, ammonium hydrogen sulfate, phosphoric acid, sodium phosphate, boric acid, borax, ammonium carbonate, chromic acid, dichromate, sulfamic acid, oxalic acid, tartaric acid, maleic acid, citric acid, ammonium citrate, formic acid, ammonia water, sodium hydroxide, ammonium fluoride, potassium ferricyanide, dimethyl sulfoxide, formamide, hydrogen peroxide, potassium titanate oxalate, sulfosalicylic acid, sulfophthalic acid, sulfoisophthalic acid, and phenolsulfonic acid.

(Sealing plate fitting process S20)
In the sealing plate fitting step S20, the electrode body 20 is housed in the exterior body 12, and the sealing plate 18 is fitted into the opening 15 of the exterior body 12. This makes the exterior body 12 (upper end surface 13) and the sealing plate 18 flush with each other. In addition, the outer peripheral surface of the sealing plate 18 faces the inner surface of the exterior body 12 (opening 15), forming a fitting portion 11.

(Laser welding step S30)
In the laser welding step S30, the fitting portion 11 between the exterior body 12 and the sealing plate 18 formed in the sealing plate fitting step S20 is laser welded. More specifically, the fitting portion 11 is laser welded over the entire circumference to form an annular molten solidified portion 50. FIG. 6 is a vertical cross-sectional view showing a schematic diagram of the laser welding step S30 according to the embodiment. FIG. 6 corresponds to FIG. 4. As shown in FIG. 6, in the laser welding step S30, a laser L is irradiated to the fitting portion 11. A part of the exterior body 12 and the sealing plate 18 is melted by the irradiation of the laser L. Then, the molten portion is solidified in a state in which the molten portion is prevented from protruding outward from the exterior body 12 by the protrusion prevention layer 60 formed on the periphery of the opening 15 in the prevention layer forming step S10, and the molten portion is solidified to form the molten solidified portion 50. The type of laser light used for laser welding and the conditions of laser welding may be the same as those of the conventional method and are not particularly limited. Furthermore, the angle formed by the laser irradiation direction, the exterior body 12 (top end surface 13), and the sealing plate 18 (horizontal surface) is typically about 90±10°, for example about 90±5°.

As described above, the manufacturing method of the electricity storage device 100 disclosed herein provides an electricity storage device 100 that suitably prevents the molten solidified portion 50 from protruding outward from the exterior body 12.

The power storage device 100 disclosed herein can be used for various purposes, but typically can be suitably used as a power source (driving power source) for motors mounted on various vehicles, such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

Although several embodiments of the technology disclosed herein have been described above, the above embodiments are merely examples. The technology disclosed herein can be implemented in various other forms. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the relevant field. The technology described in the claims includes various modifications and variations of the above-exemplified embodiments. For example, it is possible to replace part of the above-mentioned embodiments with other modified forms, and it is also possible to add other modified forms to the above-mentioned embodiments. Furthermore, if a technical feature is not described as essential, it can also be deleted as appropriate.

In the above embodiment, the extrusion prevention layer 60 is disposed on the outer surface of the side wall of the exterior body 12, but is not disposed on the upper end surface 13. However, this is not limited to this. FIG. 7 is a view corresponding to FIG. 4 of the electric storage device 200 according to the first modified example. Here, the electric storage device 200 may be the same as the electric storage device 100 except that it is provided with the extrusion prevention layer 260. As shown in FIG. 7, the extrusion prevention layer 260 is disposed on the outer surface of the short side wall 12a of the exterior body 12, and further on a part of the upper end surface 13. In other words, here, the extrusion prevention layer 260 is inverted L-shaped. As a result, the part of the extrusion prevention layer 260 provided on the upper end surface 13 side plays the role of a return. Therefore, the extrusion of the molten solidified portion 50 can be more suitably suppressed. When the extrusion prevention layer 260 is disposed on the upper end surface 13, it is preferable not to form the extrusion prevention layer 260 on the planned irradiation site of the laser L (for example, the opening 15).

In the above embodiment, the upper end of the extrusion prevention layer 60 is arranged to reach the peripheral portion 16 of the exterior body 12. However, this is not limited to this. The upper end of the extrusion prevention layer 60 does not necessarily need to reach the peripheral portion 16 of the exterior body 12. FIG. 8 is a view corresponding to FIG. 4 of the electric storage device 300 according to the second modified example. Here, the electric storage device 300 may be the same as the electric storage device 100 except that it has the extrusion prevention layer 360. As shown in FIG. 8, the upper end of the extrusion prevention layer 360 does not reach the peripheral portion 16. As shown in FIG. 8, in the modified example shown here, while the peripheral portion 16 is melted by laser irradiation, the molten solidified portion 50 is suppressed from being formed outside the exterior body 12. That is, even if the upper end of the extrusion prevention layer 360 is not formed up to the peripheral portion 16, the effect of suppressing the molten solidified portion 50 from being formed outside the exterior body 12 is exerted.

The extrusion prevention layers 260 and 360 in the above-described modified examples can be formed, for example, by adjusting the masking areas on the exterior body 12 in the above-described prevention layer formation step S10. However, the formation method is not limited to this.

As described above, specific aspects of the technology disclosed herein include those described in the following sections.
Item 1: An electricity storage device comprising: an electrode body having an electrode, a bottom, a sidewall extending from a periphery of the bottom, and an opening surrounded by the sidewall; an outer casing that houses the electrode body; a sealing plate that seals the opening; and a ring-shaped molten solidified portion formed at a fitting portion between the opening of the outer casing and the sealing plate, and having an extrusion prevention layer on at least a portion of the periphery of the opening of the outer casing that prevents the molten solidified portion from being formed outside the outer casing.
Item 2: The electricity storage device according to item 1, wherein the sealing plate is generally rectangular and plate-like, the bottom is generally rectangular having a pair of short sides and a pair of long sides, and the side walls include a pair of long side walls extending from the long sides of the bottom and facing each other, and a pair of short side walls extending from the short sides of the bottom and facing each other.
Item 3: The electricity storage device according to item 2, wherein the extrusion prevention layer is disposed on at least one pair of the short side walls.
Item 4: The electricity storage device according to item 2, wherein the extrusion prevention layer is disposed on at least one pair of the long side walls.
Item 5: The electricity storage device according to item 1 or 2, wherein the extrusion prevention layer is disposed around the entire periphery of the opening of the exterior body.
Item 6: The electricity storage device according to any one of Items 1 to 5, wherein the extrusion prevention layer is mainly made of aluminum oxide.
Item 7: The electric storage device according to any one of items 1 to 6, wherein the extrusion prevention layer is disposed on an outer surface of the side wall and at least a part of an upper end surface of the side wall of the exterior body.
Item 8: The electric storage device according to any one of Items 1 to 6, wherein the extrusion prevention layer is disposed on an outer surface of the side wall of the exterior body, and an upper end of the extrusion prevention layer is disposed at a position that does not reach a peripheral portion where the outer surface of the side wall and an upper end surface of the side wall intersect.
Item 9: A method for manufacturing an electricity storage device including an electrode body having an electrode, a bottom, a sidewall extending from a periphery of the bottom, and an opening surrounded by the sidewall, and including an outer casing that houses the electrode body, a sealing plate that seals the opening, and a ring-shaped molten solidified portion formed at a fitting portion between the opening of the outer casing and the sealing plate, the method including a prevention layer formation step of forming an extrusion prevention layer on at least a portion of the periphery of the opening of the outer casing, a sealing plate fitting step of accommodating the electrode body within the outer casing and fitting the sealing plate to the opening of the outer casing, and a laser welding step of forming the molten solidified portion by laser welding the fitting portion between the outer casing and the sealing plate after the sealing plate fitting step.
Item 10: The method for producing an electricity storage device according to Item 9, wherein the exterior body is made of aluminum or an aluminum alloy, and the prevention layer forming step is performed by anodizing.
Item 11: The method for manufacturing an electricity storage device according to item 9 or 10, wherein in the prevention layer forming step, the extrusion prevention layer is formed on an outer surface of the side wall of the exterior body and at least a portion of an upper end surface of the side wall.
Item 12: The method for manufacturing an electricity storage device according to Item 9 or 10, wherein in the prevention layer forming step, an upper end of the extrusion prevention layer is formed so as not to reach a peripheral portion where an outer surface of the side wall and an upper end surface of the side wall intersect.

1 Case 3 Positive electrode 4 Negative electrode 6 Positive electrode terminal 7 Separator 8 Negative electrode terminal 11 Fitting portion 12 Exterior body 12d Bottom portion 12a, 12b Short side wall 12e, 12f Long side wall 13 Upper end surface 13a, 13b Short side portion 13e, 13f Long side portion 15 Opening 16 Peripheral portion 18 Sealing plate 71 Liquid injection hole 20 Electrode body 30 Positive electrode current collector 31 Positive electrode active material layer 35 Positive electrode current collector member 36 Positive electrode external conductive member 40 Negative electrode current collector 41 Negative electrode active material layer 45 Negative electrode current collector member 46 Negative electrode external conductive member 50 Melted and solidified portion 60, 260, 360 Protrusion prevention layer 74, 75 Terminal pull-out hole 76 Gasket 78 Insulator 100 Electric storage device L Laser S10 Prevention layer forming process S20 Sealing plate fitting process S30 Laser welding process

Claims (8)

An electrode body having an electrode;
an exterior body that has a bottom, a side wall extending from a periphery of the bottom, and an opening surrounded by the side wall, and that houses the electrode assembly;
A sealing plate that seals the opening;
A ring-shaped molten solidified portion is formed at a fitting portion between the opening of the exterior body and the sealing plate,
The outer casing has an extrusion prevention layer on at least a part of the periphery of the opening of the outer casing, which prevents the molten solidified portion from being formed outside the outer casing,
The extrusion prevention layer is
A layer having a melting point higher than that of the molten solidified portion,
The exterior body is disposed on an outer surface of the side wall and a part of an upper end surface of the side wall.
Energy storage device. The sealing plate is generally rectangular and plate-shaped,
The bottom portion is generally rectangular having a pair of short sides and a pair of long sides,
The side walls include a pair of long side walls extending from the long sides of the bottom portion and facing each other, and a pair of short side walls extending from the short sides of the bottom portion and facing each other.
The power storage device according to claim 1 . The anti-extrusion layer is disposed on at least one pair of the short side walls.
The power storage device according to claim 2 . The anti-extrusion layer is disposed on at least one pair of the long side walls.
The power storage device according to claim 2 . The extrusion prevention layer is disposed around the entire periphery of the opening of the exterior body.
The electricity storage device according to claim 1 or 2. The extrusion prevention layer is mainly composed of aluminum oxide.
The electricity storage device according to claim 1 or 2. An electrode body having an electrode;
an exterior body that has a bottom, a side wall extending from a periphery of the bottom, and an opening surrounded by the side wall, and that houses the electrode assembly;
A sealing plate that seals the opening;
A method for manufacturing an electricity storage device including:
A step of forming an extrusion prevention layer having a melting point higher than that of the molten solidified portion on at least a portion of the periphery of the opening of the exterior body;
a sealing plate fitting step of housing the electrode assembly in the exterior housing and fitting the sealing plate into the opening of the exterior housing;
After the sealing plate fitting step, a laser welding step of laser-welding a fitting portion between the exterior body and the sealing plate to form the molten solidified portion,
In the prevention layer forming step, the extrusion prevention layer is formed on an outer surface of the side wall of the exterior body and on an upper end surface of the side wall.
A method for manufacturing an electricity storage device. The exterior body is made of aluminum or an aluminum alloy,
The prevention layer forming step is carried out by anodizing.
A method for producing the electricity storage device according to claim 7 .

Images