JP7525552B2 - Sealed battery - Google Patents

Description

The present invention relates to a sealed battery.

Conventionally, a sealed battery is known that includes an electrode body having an electrode, a battery case having an opening and housing the electrode body, a sealing plate having a terminal mounting hole and sealing the opening, and a current collector terminal having one end connected to the electrode inside the battery case and the other end inserted into the terminal mounting hole and drawn out to the outside of the sealing plate. Related prior art documents include Patent Documents 1 to 6.

For example, Patent Document 1 discloses a battery that is further provided with a resin cap that is disposed and fixed on the current collecting terminal and has a built-in safety valve. Patent Document 1 describes that the safety valve is protected from heat during welding by tilting the welded joint of the battery case outward and downward at an angle of 0.1 to 3 degrees relative to the resin cap.

Japanese Unexamined Patent Publication No. 7-183012 JP 2021-086813 A JP 2005-116208 A JP 2016-087616 A JP 2017-111896 A JP 2019-084540 A

According to the inventors' study, there was room for improvement when applying the above technology to a battery case and a sealing plate in a battery further including an insulating material that insulates the outer surface of the sealing plate from the current collector terminal when welding the battery case and the sealing plate. That is, in recent batteries with high energy density, the gap between the current collector terminal and the fitting portion provided on the sealing plate is narrow, and the laser welding point is close to the insulating material. In addition, when welding with a laser, the incident angle of the laser may be slightly shifted due to, for example, a change in the posture of the workpiece. This may cause the reflected light of the laser to hit the resin insulating material, causing the insulating material to be burned. As a result, the insulating material may deteriorate, and the insulating properties of the insulating material may decrease or the airtightness of the battery may decrease. Therefore, it is necessary to protect the insulating material during laser welding.

The present invention was made in consideration of the above circumstances, and its main objective is to provide a sealed battery in which deterioration of the insulating material during laser welding is suppressed.

The present invention provides a sealed battery comprising an electrode body having an electrode, a battery case having an opening and housing the electrode body, a sealing plate having a terminal mounting hole and sealing the opening, a fitting portion between the battery case and the sealing plate, an electrode body connection portion connected to the electrode inside the battery case, a shaft portion inserted into the terminal mounting hole, and an external connection portion exposed on the outer surface of the sealing plate, and a resin insulating material that insulates the outer surface of the sealing plate from the external connection portion. At least in the region where the fitting portion and the insulating material are closest to each other, the sealing plate has a sealing plate inclined portion that is inclined toward the fitting portion at an inclination angle of 5° or more, and the battery case has a battery case inclined portion that is flush with the sealing plate inclined portion at the fitting portion and inclined outward and away from the sealing plate, and the fitting portion including the sealing plate inclined portion and the battery case inclined portion is laser welded.

By setting the inclination angle of the battery case inclined portion to 5° or more, the reflected light of the laser is less likely to be reflected toward the insulating material during laser welding. Furthermore, by providing an inclined portion of the sealing plate, even if a small amount of light is reflected toward the insulating material, the reflected light can be blocked. Therefore, for example, even if the portion to be laser welded is close to the insulating material or the incident angle of the laser is slightly shifted during laser welding, the reflected light of the laser is less likely to hit the insulating material. Therefore, scorching of the insulating material can be suppressed, and thus a decrease in the insulating properties of the insulating material and a decrease in the airtightness of the battery can be suppressed.

FIG. 1 is a perspective view showing a schematic diagram of a sealed battery according to one embodiment. FIG. 2 is an exploded perspective view of FIG. FIG. 3 is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a plan view of FIG. FIG. 5 is a vertical cross-sectional view showing the vicinity of the fitted portion in the laser welding process. FIG. 6(A) is a vertical cross-sectional view showing the vicinity of a groove portion according to a first modified example, FIG. 6(B) is a vertical cross-sectional view showing the vicinity of a groove portion according to a second modified example, and FIG. 6(C) is a vertical cross-sectional view showing the vicinity of a groove portion according to a third modified example.

Below, with reference to the drawings, a preferred embodiment of the technology disclosed herein will be described. Note that matters other than those specifically mentioned in this specification that are necessary for implementing the present invention (for example, the general configuration and manufacturing process of a battery that do not characterize the present invention) can be understood as design matters for a person skilled in the art based on the prior art in the field. The technology disclosed here can be implemented based on the contents disclosed in this specification and the technical common sense in the field. In addition, below, the same reference numerals are used for components and parts that perform the same function, and duplicate explanations may be omitted or simplified.

In this specification, the term "battery" refers to any power storage device capable of extracting electrical energy, and is a concept that includes primary batteries and secondary batteries. In addition, in this specification, the term "secondary battery" refers to any power storage device that can be repeatedly charged and discharged by the movement of charge carriers between the positive and negative electrodes via an electrolyte. The electrolyte may be any of a liquid electrolyte (electrolytic solution), a gel electrolyte, and a solid electrolyte. Such secondary batteries include so-called storage batteries (chemical batteries) such as lithium ion secondary batteries and nickel-metal hydride batteries, as well as capacitors (physical batteries) such as electric double layer capacitors. Below, an embodiment in the case of a lithium ion secondary battery will be described.

<Sealed battery 100>
Fig. 1 is a perspective view of a sealed battery 100. Fig. 2 is an exploded perspective view illustrating the configuration of the sealed battery 100. In the following description, the reference characters L, R, F, Rr, U, and D represent left, right, front, rear, top, and bottom. Also, the symbols X, Y, and Z in the drawings represent the short side direction, long side direction, and up-down direction of the sealed battery 100. However, these are merely directions for the convenience of explanation and do not limit the installation form of the sealed battery 100 in any way.

As shown in FIG. 2, the sealed battery 100 includes an exterior body 10, an electrode body 20, a collector terminal 30, and an insulating material 40. Although not shown, the sealed battery 100 further includes an electrolyte. In FIG. 2, an assembly part (hereinafter referred to as a lid assembly 15A) in which the collector terminal 30 and the insulating material 40 are insert-molded into the sealing plate 15 of the exterior body 10 is shown separately from other parts. Furthermore, in FIG. 2, the sealing plate 15, the collector terminal 30, and the insulating material 40 are shown separately for the electrode on one side (the right side of FIG. 2).

The exterior body 10 includes a battery case 11 and a sealing plate (lid) 15. As shown in FIG. 1, the exterior body 10 has a flat rectangular parallelepiped (square) outer shape. The material of the exterior body 10 may be the same as that conventionally used, and there are no particular restrictions. The exterior body 10 (battery case 11 and sealing plate 15) is made of, for example, aluminum, aluminum alloy, stainless steel, iron, iron alloy, etc. Here, the exterior body 10 is made of aluminum.

As shown in FIG. 2, the battery case 11 is a housing that contains the electrode body 20 and the electrolyte. The battery case 11 is a bottomed, square-shaped container with an opening 12 on the top surface. The opening 12 is approximately rectangular. As shown in FIG. 1, the battery case 11 includes a bottom wall 11a having long and short sides, a pair of long side walls 11b that extend upward from the long side of the bottom wall 11a and face each other, and a pair of short side walls 11c that extend upward from the short side of the bottom wall 11a and face each other. The bottom wall 11a is approximately rectangular. In this specification, the term "approximately 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, a shape with a notch at the corner, and the like.

Although not particularly limited, the thickness (plate thickness) of the battery case 11 is preferably approximately 0.5 mm or more, for example 1 mm or more, from the standpoint of durability, etc., and is preferably approximately 3 mm or less, for example 2 mm or less, from the standpoint of cost and energy density.

The sealing plate 15 is a plate-shaped member that fits into the opening 12 of the battery case 11 and seals the opening 12. The sealing plate 15 is substantially rectangular. The outer shape of the sealing plate 15 is smaller than the opening 12 of the battery case 11. The sealing plate 15 faces the bottom wall 11a of the battery case 11. The sealing plate 15 has an inner surface 16 facing the inside of the sealed battery 100 and an outer surface 17 facing the outside. The sealing plate 15 has two terminal mounting holes 18 that penetrate the inner surface 16 and the outer surface 17. The terminal mounting holes 18 are provided at both ends of the long side direction Y of the sealing plate 15. The terminal mounting hole 18 on one side (left side in FIG. 2) is for the positive electrode, and the terminal mounting hole 18 on the other side (right side in FIG. 2) is for the negative electrode.

Although not particularly limited, the thickness (plate thickness) of the sealing plate 15 is preferably approximately 0.3 mm or more, for example 0.5 mm or more, from the viewpoint of durability, etc., and is preferably approximately 2 mm or less, for example 1.5 mm or less, from the viewpoint of cost and energy density. The thickness of the sealing plate 15 may be thinner than the thickness of the battery case 11.

At least a part of the surface of the sealing plate 15 that contacts the insulating material 40 is roughened. The roughening process is a surface treatment that increases the surface area and enhances the anchoring effect by forming irregularities on the surface, thereby improving the bonding and adhesion with the insulating material 40. The roughening process can be performed, for example, by laser irradiation or sandblasting. The roughened part of the sealing plate 15 constitutes the roughened part 15b (see FIG. 3). The roughened part 15b is formed on the inner surface 16 around the terminal mounting hole 18 and the outer surface 17 around the terminal mounting hole 18. However, the roughened part 15b may be formed on the entire part of the sealing plate 15 that contacts the insulating material 40. The roughened part 15b is not essential and can be omitted.

The electrode body 20 is accommodated inside the battery case 11. The electrode body 20 is accommodated in the battery case 11 in a state where it is covered with, for example, a resin insulating film (not shown). The electrode body 20 includes a positive electrode sheet 21, a negative electrode sheet 22, and a separator sheet (not shown) arranged between the positive electrode sheet 21 and the negative electrode sheet 22. The positive electrode sheet 21 and the negative electrode sheet 22 are examples of electrodes. The electrode body 20 is a wound electrode body in which a strip-shaped positive electrode sheet 21 and a strip-shaped negative electrode sheet 22 are stacked with two strip-shaped separator sheets interposed therebetween and wound in the longitudinal direction. However, the electrode body 20 may be a laminated electrode body in which a square-shaped positive electrode and a square-shaped negative electrode are stacked in an insulated state.

The positive electrode sheet 21 is a member in which a positive electrode active material layer containing a positive electrode active material is fixed on at least one surface of a positive electrode collector (e.g., aluminum foil). The configuration of the positive electrode sheet 21 is not particularly limited, and may be the same as that used in conventionally known batteries. As the positive electrode active material, any conventionally known material can be used without particular restriction. One example is a lithium transition metal composite oxide. The negative electrode sheet 22 is a member in which a negative electrode active material layer containing a negative electrode active material is fixed on at least one surface of a negative electrode collector (e.g., copper foil). The configuration of the negative electrode sheet 22 is not particularly limited, and may be the same as that used in conventionally known batteries. As the negative electrode active material, any conventionally known material can be used without particular restriction. One example is a carbon material such as graphite. The separator sheet is an insulating resin sheet in which a plurality of fine through holes through which charge carriers can pass are formed. The configuration of the separator sheet is not particularly limited, and may be the same as that used in conventionally known batteries.

The positive electrode sheet 21 is arranged inside the battery case 11 so that one end is at one end in the long side direction Y (the left end in FIG. 2). The negative electrode sheet 22 is arranged inside the battery case 11 so that one end is at the other end in the long side direction Y (the right end in FIG. 2). Although shown in a separated state in FIG. 2, in the completed sealed battery 100, a current collecting terminal 30 is welded to each of the positive electrode sheet 21 and the negative electrode sheet 22.

As shown in Figs. 1 and 2, one current collecting terminal 30 is provided on each end of the sealing plate 15 in the long side direction Y. As shown in Fig. 2, one end is disposed inside the exterior body 10, and the other end is inserted into the terminal mounting hole 18 and disposed outside the sealing plate 15. The positive electrode side current collecting terminal 30 is made of, for example, aluminum or an aluminum alloy. The negative electrode side current collecting terminal 30 is made of, for example, copper or a copper alloy.

3 is a cross-sectional view taken along line III-III in FIG. 1. In FIG. 3, only one long side wall 11b of the battery case 11 is shown, and the other long side wall 11b is omitted. As shown in FIGS. 2 and 3, the current collecting terminal 30 has a base portion 31, an electrode body connection portion 32, a shaft portion 33, and an external connection portion 34. As shown in FIG. 2, the base portion 31 is configured in a rectangular flat plate shape and extends horizontally. The base portion 31 is configured to a size that can be inserted into the terminal mounting hole 18. The electrode body connection portion 32 is disposed inside the battery case 11. The electrode body connection portion 32 is formed in a plate shape here and extends downward from the rear end of the base portion 31. The tip of the electrode body connection portion 32 is electrically connected to the positive electrode sheet 21 or the negative electrode sheet 22 of the electrode body 20 inside the battery case 11.

The shaft portion 33 is disposed between the electrode body connection portion 32 and the external connection portion 34, and is inserted into the terminal mounting hole 18. The shaft portion 33 extends upward from the base portion 31. The external connection portion 34 is disposed so as to be exposed on the outer surface 17 of the exterior body 10. The external connection portion 34 is provided above the shaft portion 33. The external connection portion 34 is configured to have a size that allows it to be inserted into the terminal mounting hole 18. Due to the difference in size between the base portion 31, the shaft portion 33, and the external connection portion 34, the shaft portion 33 appears to be constricted relative to the base portion 31 and the external connection portion 34.

At least a portion of the surface of the collector terminal 30 that comes into contact with the insulating material 40 is roughened, similar to the roughened surface treatment 15b of the sealing plate 15. The roughened surface treatment portion of the collector terminal 30 constitutes the roughened surface treatment portion 30a (see FIG. 3). In this example, the roughened surface treatment portion 30a is formed on the shaft portion 33 and the upper surface of the base portion 31. However, the roughened surface treatment portion 30a may be formed on, for example, the entire portion of the collector terminal 30 that comes into contact with the insulating material 40. Furthermore, the roughened surface treatment portion 15b is not essential and may be omitted.

The insulating material 40 is a member that prevents electrical conduction between the sealing plate 15 and the current collecting terminal 30. The insulating material 40 is made of resin. The insulating material 40 is made of, for example, a fluorine-based resin such as perfluoroalkoxyalkane (PFA) or polytetrafluoroethylene (PTFE), or a synthetic resin material such as polyphenylene sulfide (PPS). Inorganic fillers may be added to the synthetic resin material. As shown in FIG. 3, the insulating material 40 has a cylindrical portion 41, a first flange portion 42, and a second flange portion 43. The cylindrical portion 41, the first flange portion 42, and the second flange portion 43 are integrally formed.

The cylindrical portion 41 is located between the terminal mounting hole 18 and the shaft portion 33 of the current collector terminal 30. The cylindrical portion 41 insulates the terminal mounting hole 18 and the shaft portion 33. The first flange portion 42 extends horizontally from the cylindrical portion 41 along the inner surface 16 of the sealing plate 15. The first flange portion 42 insulates the inner surface 16 of the sealing plate 15 and the base portion 31. The second flange portion 43 extends horizontally from the cylindrical portion 41 along the outer surface 17 of the sealing plate 15. The second flange portion 43 insulates the outer surface 17 of the sealing plate 15 and the external connection portion 34. The outer shapes of the first flange portion 42 and the second flange portion 43 are larger than the outer shapes of the base portion 31 and the external connection portion 34 of the current collector terminal 30. As shown in Figures 1 and 3, the second flange 43 protrudes outward from the current collecting terminal 30 in a plan view and is exposed to the outside.

As shown in FIG. 2, the lid assembly 15A is an assembly part in which the current collector terminal 30 and the insulating material 40 are assembled to the sealing plate 15 by insert molding (integral molding). The sealing plate 15 and the current collector terminal 30 are firmly fixed to the insulating material 40 by the roughened surface treatment portion 15b of the sealing plate 15 and the roughened surface treatment portion 30a of the current collector terminal 30. As a result, the current collector terminal 30 is fixed to the sealing plate 15 without the base portion 31 being crimped and without direct contact with the sealing plate 15. Furthermore, the sealing plate 15 and the current collector terminal 30 are in close contact with the insulating material 40 in the roughened surface treatment portion 15b and the roughened surface treatment portion 30a, so that the terminal mounting hole 18 is sealed by the insulating material 40. The current collector terminal 30 and the insulating material 40 are fixed to the sealing plate 15 so that they cannot move.

According to the inventor's investigations, when the sealing plate 15, the current collecting terminal 30, and the insulating material 40 are integrated by insert molding, it is desirable to increase the contact area between the sealing plate 15 and the insulating material 40 in order to improve adhesion. This makes the external connection portion 34 and/or the second flange portion 43 larger than in the past, and the insulating material 40 (second flange portion 43) and the fitting portion 14 tend to be close to each other on the outer surface 17 of the sealing plate 15. Therefore, it is particularly effective to apply the technology disclosed herein.

4 is a plan view of FIG. 1. As shown in FIGS. 3 and 4, the fitting portion (joint) of the opening 12 of the battery case 11 and the sealing plate 15 constitutes the fitting portion 14. As shown in FIG. 3, the fitting portion 14 is located below the extension line of the outer surface 17 of the sealing plate 15 in the vertical direction. The fitting portion 14 is located below the lower end of the insulating material 40. As shown in FIG. 4, the fitting portion 14 is located on the outer surface 17 side of the sealing plate 15. The fitting portion 14 extends along the inner peripheral edge (inner side wall) of the battery case 11 and the outer peripheral edge (side wall) of the sealing plate 15. The fitting portion 14 is formed continuously in a substantially annular shape along the boundary between the battery case 11 and the sealing plate 15 in a plan view. The fitting portion 14 is substantially rectangular. Here, the current collector terminal 30 and the insulating material 40 are provided at both ends in the long side direction Y, respectively. Therefore, the fitting portion 14 is close to the insulating material 40 at both ends in the long side direction Y. Here, the fitting portion 14 is closest to the insulating material 40 in region A at both ends in the long side direction Y.

Area A is a range of length that is approximately equal to the length of the insulating material 40 in the long side direction Y (allowing for an error of about ±1 mm). Area A is an example of the "area where the fitting portion 14 and the insulating material 40 are closest to each other." Although not particularly limited, in area A, the distance between the fitting portion 14 and the insulating material 40 (second flange portion 43) can be approximately 5 mm or less, typically 3 mm or less, for example about 1 to 2 mm.

At least in region A, the battery case 11 has a battery case inclined portion S1 in the fitting portion 14. The battery case inclined portion S1 is an inclined surface that inclines outward at an inclination angle θ1 in a direction away from the sealing plate 15. The inclination angle θ1 is an inclination angle based on the outer surface 17 of the sealing plate 15 (which is the same as the horizontal surface in this case). More specifically, the inclination angle θ1 is the smaller of the angles between the extension line of the outer surface 17 of the sealing plate 15 and the extension line of the battery case inclined portion S1. In the battery case inclined portion S1, the inclination angle θ1 is constant here. The battery case inclined portion S1 is a flat surface.

The inclination angle θ1 is preferably 5° or more, more preferably 10° or more, for example 20° or more, and typically 80° or less, and is preferably 60° or less, for example 45° or less, 30° or less. By setting the inclination angle θ1 to a predetermined value or more, the reflected laser light is less likely to be reflected toward the insulating material 40 during laser welding, and scorching of the insulating material 40 can be suppressed to a higher level. By setting the inclination angle θ1 to a predetermined value or less, the molten metal is less likely to flow along the inclination during laser welding, and weldability can be improved.

In addition, at a position facing the battery case inclined portion S1, the sealing plate 15 has a sealing plate inclined portion S2. The sealing plate inclined portion S2 is an inclined surface inclined at an inclination angle θ2 toward the fitting portion 14. At the fitting portion 14, the sealing plate inclined portion S2 and the battery case inclined portion S1 are flush with each other. The sealing plate inclined portion S2 can also function as a shielding portion that shields reflected light during laser welding. The inclination angle θ2 is an inclination angle based on the outer surface 17 of the sealing plate 15 (which is the same as the horizontal surface here). In detail, the inclination angle θ2 is the smaller angle between the extension line of the outer surface 17 of the sealing plate 15 and the extension line of the sealing plate inclined portion S2. In the sealing plate inclined portion S2, the inclination angle θ2 is constant here. The sealing plate inclined portion S2 is a flat surface. The sealing plate inclined portion S2 is provided in a slope shape from the outer surface 17 of the sealing plate 15.

In this embodiment, the inclination angle θ2 is 5° or more. By setting the inclination angle θ2 to a predetermined value or more, the reflected light of the laser is less likely to be reflected toward the insulating material 40 during laser welding, and scorching of the insulating material 40 can be appropriately suppressed. The inclination angle θ2 is preferably 10° or more, for example, 20° or more, or even 30° or more, and is typically 80° or less, for example, 60° or less. By setting the inclination angle θ2 to a predetermined value or more, the effect of blocking reflected light can be exerted at a high level. By setting the inclination angle θ2 to a predetermined value or less, the molten metal is less likely to flow along the inclination during laser welding, and weldability can be improved.

In this embodiment, the inclination angle θ2 is the same as the inclination angle θ1. However, the inclination angles θ1 and θ2 may be different. For example, θ1 may be greater than θ2, or θ1 may be less than θ2. The height t1 of the battery case inclined portion S1 (length in the vertical direction Z; the same applies below) is preferably 2/3 or less of the thickness of the insulating material 40, and more preferably 1/2 or less. The height t2 of the sealing plate inclined portion S2 is preferably 2/3 or less of the thickness of the insulating material 40, and more preferably 1/2 or less, for example 1/3 or less. In addition, the sum of t1 and t2 is preferably typically smaller than the thickness of the insulating material 40.

4, the battery case inclined portion S1 and the sealing plate inclined portion S2 are provided around the entire circumference of the fitting portion 14. However, the battery case inclined portion S1 and the sealing plate inclined portion S2 may be provided at least in the area where the fitting portion 14 and the insulating material 40 are closest to each other. For example, when the fitting portion 14 is substantially rectangular, the battery case inclined portion S1 and the sealing plate inclined portion S2 may be provided at least in the area A of the long side portion of the fitting portion 14 facing the insulating material 40. This allows the effect of the technology disclosed herein to be properly exhibited. The battery case inclined portion S1 and the sealing plate inclined portion S2 may not be provided in any portion other than the area A, for example, in the central portion of the long side direction Y and/or the entire short side direction X. The battery case inclined portion S1 and the sealing plate inclined portion S2 may be provided, for example, in addition to the above-mentioned area A, in the area where the short side portion of the fitting portion 14 and the insulating material 40 face each other, or may be provided continuously along the long side direction Y with approximately the same length as the long side portion of the fitting portion 14.

The exterior body 10 is hermetically sealed (closed) by laser welding the entire circumference of the fitting portion 14 including the battery case inclined portion S1 and the sealing plate inclined portion S2. In the laser-welded portion of the fitting portion 14, the constituent metal of the battery case 11 and the constituent metal of the sealing plate 15 are melted to form the laser welded portion 14W. It is preferable that the laser welded portion 14W is entirely located below the extension line of the outer surface 17 of the sealing plate. In other words, it is preferable that the upper end of the laser welded portion 14W is located below the outer surface 17 of the sealing plate 15 in a cross-sectional view. Since the laser welded portion 14W does not protrude from the outer surface 17 of the sealing plate 15, it is possible to prevent the laser welded portion 14W from interfering with other members and being damaged or broken.

<Method of manufacturing sealed battery 100>
The sealed battery 100 as described above can be manufactured by a manufacturing method including, for example, (1) a preparation step and (2) a laser welding step. Here, the preparation step further includes (1A) an insert molding step.

(1) In the preparation step, the battery case 11 and the sealing plate 15 are prepared. In addition, other necessary parts as described above are prepared. Here, the battery case 11 has a battery case inclined portion S1. The sealing plate 15 has a sealing plate inclined portion S2. The battery case inclined portion S1 is formed, for example, in a tapered shape so that the inner peripheral edge of the battery case 11 widens as it approaches the outer edge. The sealing plate inclined portion S2 is formed, for example, in a tapered shape so that the outer peripheral edge of the sealing plate 15 widens as it moves away from the opening 12.

(1A) In the insert molding process, the current collector terminal 30 and the insulating material 40 are integrated with the sealing plate 15 to produce an assembly part (for example, the lid assembly 15A). The lid assembly 15A can be produced by insert molding the sealing plate 15, the current collector terminal 30, and the insulating material 40. This reduces the number of parts and makes it easier to form a conductive path than the conventional method using rivets. Insert molding can be performed according to a conventionally known method, for example, as described in JP 2021-086813 A, JP 2021-086814 A, Japanese Patent No. 3986368 A, Japanese Patent No. 6648671 A, etc. For example, it can be produced by a method including a part setting process, a positioning process, an upper die setting process, an injection molding process, an upper die release process, and a part removal process, using a molding die having a lower die and an upper die.

In the part setting process, the collector terminal 30 is inserted into the terminal mounting hole 18 of the sealing plate 15, and then the sealing plate 15 is mounted on the lower mold. In the positioning process, the collector terminal 30 is positioned and fixed. In the upper mold setting process, the upper mold is mounted together with the lower mold so as to sandwich the sealing plate 15 and the collector terminal 30 in the vertical direction. In the injection molding process, the molding die is first heated. Next, molten resin is injected into the molding die. The molten resin flows from the upper mold through the terminal mounting hole 18 into the lower mold. The molding die and the molded product are then cooled. This integrates the insulating material 40, the sealing plate 15, and the collector terminal 30. In the upper mold release process, the upper mold is separated from the lower mold. In the part removal process, the molded product is removed from the lower mold.

(2) In the laser welding process, after the electrode body 20 is accommodated inside the battery case 11, the sealing plate 15 is fitted into the opening 12 of the battery case 11. As a result, the battery case inclined portion S1 of the battery case 11 and the sealing plate inclined portion S2 of the sealing plate 15 are combined so as to be flush with each other. Next, the joint (fitting portion 14) between the battery case 11 and the sealing plate 15 is welded with a laser. The type of laser light used for laser welding and the conditions for laser welding may be the same as those used in the past and are not particularly limited. The angle between the laser irradiation direction and the outer surface 17 (horizontal surface) of the sealing plate 15 is typically about 90±10°, for example about 90±5°. The fitting portion 14 is welded around the entire circumference, so that the sealing plate 15 and the battery case 11 are welded together without any gaps.

5 is a vertical cross-sectional view showing the vicinity of the fitting portion 14 in this process. In this embodiment, as shown by the thick arrow in FIG. 5, the fitting portion 14 is irradiated with laser light IL. As shown by the thin arrow in FIG. 5, the laser light IL irradiated to the fitting portion 14 is reflected by the fitting portion 14, and the reflected light RL can be reflected outward. However, in this embodiment, the reflected light RL is not easily reflected on the insulating material 40 side. Even if a small amount of reflected light RL is reflected on the insulating material 40 side, the reflected light RL can be blocked by the sealing plate inclined portion S2. Therefore, for example, even if the fitting portion 14 is close to the insulating material 40 as in the region A, or the incident angle of the laser light IL is slightly shifted, the reflected laser light RL is not easily incident on the insulating material 40. With the above effects, the insulating material 40 can be prevented from being burned, and the deterioration of the insulating property of the insulating material 40 and the deterioration of the airtightness of the sealed battery 100 can be suppressed.

<Battery uses>
The sealed battery 100 can be used for various purposes, but 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, a truck, etc. The type of vehicle is not particularly limited, but examples thereof include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), a battery electric vehicle (BEV), etc.

The following describes some examples of the present invention, but it is not intended that the present invention be limited to those examples.

First, as shown in Table 1, battery cases with different inclination angles θ1 of the inclined portion of the battery case in the range of 0.1 to 60° and sealing plates with different inclination angles θ2 of the inclined portion of the sealing plate in the range of 0.1 to 60° were prepared. Next, the battery case and sealing plate were combined so that θ1 = θ2, and the sealing plate was fitted into the opening of the battery case. The seam (fitting portion) between the battery case and the sealing plate was then welded with a laser. After the laser welding, it was visually confirmed whether the insulating material was scorched or not. The results are shown in Table 1. In Table 1, if the insulating material was scorched, it is indicated as "Yes," and if no discoloration (scorching) of the insulating material was observed, it is indicated as "No."

As shown in Table 1, in Examples 1 and 2, where the inclination angle θ1 was set to 0.1 to 3° following Patent Document 1, the reflected laser light hit the insulating material, causing it to burn. In contrast, in Examples 3 to 9, where the inclination angle θ1 was set to 5° or more (here, 5 to 60°), no discoloration (burning) of the insulating material was observed. In other words, deterioration of the insulating material during laser welding was suppressed. These results demonstrate the significance of the technology disclosed herein.

The sealed battery proposed herein has been described above, but the above embodiment is merely an example. The present invention can be embodied in various other forms. The technology disclosed herein can be implemented based on the contents disclosed in this specification and common technical knowledge in the relevant field. The technology described in the claims includes various modifications and variations of the above-exemplified embodiment.

<First Modification>
For example, in the embodiment of FIG. 3 described above, the sealing plate inclined portion S2 is continuous from the outer surface 17 of the sealing plate 15 in a slope shape. However, this is not limited to this. FIG. 6A is a vertical cross-sectional view showing the vicinity of the groove portion according to the first modification. In this modification, the sealing plate 115 is similar to the sealing plate 15 except that it has a vertical wall portion W between the outer surface 17 and the sealing plate inclined portion S12. The vertical wall portion W extends upward from the end (the right end in FIG. 6A) of the sealing plate inclined portion S1 opposite to the fitting portion 14. The vertical wall portion W protrudes upward from the extension line (the dashed line in FIG. 6A) of the sealing plate inclined portion S12. This allows the reflected light to be shielded at a higher level in the unlikely event that a small amount of reflected light is reflected toward the insulating material 40.

<Second Modification>
For example, in the embodiment of Fig. 3 described above, the inclination angle θ1 and the inclination angle θ2 are the same. However, this is not limited to this. Fig. 6B is a vertical cross-sectional view showing the vicinity of the groove portion according to the second modification. In this modification, the sealing plate 215 is similar to the sealing plate 15 except that it has a sealing plate inclination portion S22 instead of the sealing plate inclination portion S2. The inclination angle θ22 of the sealing plate inclination portion S22 is larger than the inclination angle θ1 of the battery case inclination portion S1. This allows the sealed battery 100 to be made more compact.

<Third Modification>
For example, in the embodiment of FIG. 3 described above, the battery case inclined portion S1 and the sealing plate inclined portion S2 are flat surfaces. However, this is not limited thereto. The battery case inclined portion S1 and/or the sealing plate inclined portion S2 may be curved surfaces. FIG. 6C is a vertical cross-sectional view showing the vicinity of the groove portion according to the third modified example. In this modified example, the sealing plate 315 is similar to the sealing plate 15 except that it has the sealing plate inclined portion S32 instead of the sealing plate inclined portion S2. In the sealing plate inclined portion S32, the inclination angle changes continuously so that it becomes larger as it moves away from the fitting portion 14. The sealing plate inclined portion S32 is a curved surface. In addition, when the sealing plate inclined portion S32 is a curved surface, it is sufficient that the inclination angle θ32 is 5° or more at the part with the greatest inclination (the end portion opposite the fitting portion 14 in FIG. 6C). ^*1 This allows the sealed battery 100 to be made compact and the reflected light to be more reliably blocked. ^*2

As described above, specific aspects of the technology disclosed herein include those described in the following sections.
Item 1: A sealed battery comprising: an electrode body having an electrode; a battery case having an opening and accommodating the electrode body; a sealing plate having a terminal mounting hole and sealing the opening; a current collecting terminal having an engagement portion between the battery case and the sealing plate, an electrode body connection portion connected to the electrode inside the battery case, a shaft portion inserted into the terminal mounting hole, and an external connection portion exposed on the outer surface of the sealing plate; and a resin insulating material that insulates the outer surface of the sealing plate from the external connection portion, wherein at least in a region where the engagement portion and the insulating material are closest to each other, the sealing plate has a sealing plate inclined portion that is inclined toward the engagement portion at an inclination angle of 5° or more, and the battery case has a battery case inclined portion that is flush with the sealing plate inclined portion at the engagement portion and is inclined outwardly and in a direction away from the sealing plate, and the engagement portion including the sealing plate inclined portion and the battery case inclined portion are laser welded.
Item 2: The sealed battery according to item 1, wherein the sealing plate, the current collecting terminal, and the insulating material are insert-molded.
Item 3: The sealed battery according to item 1 or 2, wherein the sealing plate inclined portion and the battery case inclined portion are flat surfaces, and the inclination angle of the sealing plate inclined portion and the inclination angle of the battery case inclined portion are the same.
Item 4: The sealed battery according to any one of items 1 to 3, wherein the sealing plate inclined portion and the battery case inclined portion are flat surfaces, and the inclination angle of the sealing plate inclined portion is larger than the inclination angle of the battery case inclined portion.
Item 5: The sealed battery according to any one of items 1 to 4, wherein the sealing plate has a vertical wall portion between the sealing plate inclined portion and the insulating material, the vertical wall portion protruding outward beyond an extension line of the sealing plate inclined portion.
Item 6: The sealed battery according to any one of items 1 to 5, wherein the inclined portion of the sealing plate is a curved surface that curves toward the fitting portion.
Item 7: The sealed battery according to any one of items 1 to 6, wherein the fitting portion is substantially rectangular, and the sealing plate inclined portion and the battery case inclined portion are provided at least in an area of a long side portion of the fitting portion that faces the insulating material.

REFERENCE SIGNS LIST 10 Exterior body 11 Battery case S1 Battery case inclined portion 14 Fitting portion 14W Laser welded portion 15 Sealing plate S2 Sealing plate inclined portion 15A Lid assembly 18 Terminal mounting hole 20 Electrode body 30 Current collecting terminal 34 External connection portion 40 Insulating material 43 Second flange portion 100 Sealed battery

Claims (7)

An electrode body having an electrode;
a battery case having an opening and housing the electrode assembly;
a sealing plate having a terminal mounting hole and sealing the opening;
a fitting portion between the battery case and the sealing plate;
a current collecting terminal including an electrode body connection portion connected to the electrode inside the battery case, an axis portion inserted into the terminal mounting hole, and an external connection portion exposed on an outer surface of the sealing plate;
a resin insulating material that insulates the outer surface of the sealing plate from the external connection portion;
Equipped with
At least in a region where the fitting portion and the insulating material are closest to each other,
the sealing plate has a sealing plate inclined portion that is inclined at an inclination angle of 5° or more toward the fitting portion,
the battery case has a battery case inclined portion that is flush with the sealing plate inclined portion at the fitting portion and inclined outwardly and in a direction away from the sealing plate,
A sealed battery, wherein the fitting portion including the sealing plate inclined portion and the battery case inclined portion is laser welded. The sealing plate, the current collecting terminal, and the insulating material are insert-molded.
2. The sealed battery according to claim 1. The sealing plate inclined portion and the battery case inclined portion are flat surfaces,
The inclination angle of the sealing plate inclined portion and the inclination angle of the battery case inclined portion are the same.
3. The sealed battery according to claim 1 or 2. The sealing plate inclined portion and the battery case inclined portion are flat surfaces,
the inclination angle of the sealing plate inclined portion is larger than the inclination angle of the battery case inclined portion;
3. The sealed battery according to claim 1 or 2. the sealing plate has a vertical wall portion between the sealing plate inclined portion and the insulating material, the vertical wall portion protruding outward beyond an extension line of the sealing plate inclined portion;
3. The sealed battery according to claim 1 or 2. The sealing plate inclined portion is a curved surface that curves toward the fitting portion.
3. The sealed battery according to claim 1 or 2. The fitting portion is generally rectangular,
the sealing plate inclined portion and the battery case inclined portion are provided at least in a region of a long side portion of the fitting portion that faces the insulating material;
3. The sealed battery according to claim 1 or 2.

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