JP6941814B2 - Manufacturing method of sealed battery - Google Patents

Description

The present invention relates to a method for manufacturing a sealed battery in which a lid is fitted and welded to a fitting portion of the battery.

A lithium thionyl chloride battery is known as a battery capable of obtaining a stable output voltage for a relatively long period of time. Thionyl chloride used by this battery as a reactant decomposes in air. For this reason, the lithium thionyl chloride battery adopts a completely sealed structure that shuts off the outside air, enabling stable use over a long period of time. Further, in order to enable stable use of a lithium manganese dioxide battery for a long period of time, a completely sealed structure is required so that moisture can be prevented from entering the battery.

FIG. 7 is a cross-sectional view showing a conventional structural example of a sealed battery. Reference numeral 115 is a positive electrode plate obtained by applying an active material paste mainly composed of manganese dioxide to the electrode plate core body. Reference numeral 111 is a positive electrode tab terminal to which the positive electrode active material paste is peeled off and welded to the electrode plate core body appearing therein. Reference numeral 116 is a negative electrode plate mainly composed of lithium, to which a negative electrode tab terminal 113 is attached. Reference numeral 117 is an electrode wound product in which a positive electrode plate 115 and a negative electrode plate 116 are spirally wound via a separator 118. The positive electrode tab terminal 111 is present on the outermost periphery of the electrode wound product 117. The electrode wound product 117 is housed in a battery outer can 112 made of a metal such as iron, aluminum, or SUS. Reference numeral 119 is a battery lid in which the negative electrode terminal 14 is penetrated and fixed through the central through hole of the sealing plate 20 via the gasket 21. The negative electrode tab terminal 113 and the negative electrode terminal 114 are welded together. After injecting the electrolytic solution into the battery outer can 112, the positive electrode tab terminal 111 extends linearly along the inner surface of the battery outer can 112 to the opening edge of the battery outer can 112. The battery lid 119 is fitted to the opening edge of the battery outer can 112 so that the positive electrode tab terminal 111 is sandwiched between the opening edge of the battery outer can 112 and the battery lid 119. By welding the battery outer can 112 and the battery lid 119 to irradiate the fitting portion 122 or the vicinity of the fitting portion 122 with a laser beam, the battery is sealed and the positive electrode tab terminal 111 is attached to the battery outer can 112 and the battery lid 119. Is electrically connected to.

However, as shown in FIG. 8, in welding in which the battery lid 119 is fitted into the opening 110 at the upper end of the battery outer can 112 and the fitting portion 122 is irradiated with a laser, the outer peripheral edge of the battery lid 119 is the battery outer can 112. It is in a state of being butted against the inner circumference (opening end edge) of the opening end portion 123 of. When the predetermined portions of the fitting portions 122 are welded while maintaining this state, the battery lid 119 falls inside the battery outer can 112 at the welded portion, or the battery lid 119 becomes a battery on the opposite side of the welded portion due to the reaction thereof. It may be lifted to the outside of the outer can 112. As a result, the battery lid 119 may be displaced diagonally as shown in FIG. 8, and as a result, the above-mentioned welding defect may occur.

In order to ensure the close contact between the battery outer can and the battery lid by conventional laser welding, after temporarily fixing three or more temporary fixing points of the battery outer can fitting parts apart from each other, the fitting is performed. Some parts are laser-welded on the entire circumference (see, for example, Patent Document 1). 9A and 9B are views showing a method of laser welding the conventional battery outer can 212 and the battery lid 219 described in Patent Document 1.

First, as shown in FIG. 9A, the fitting portions 222 are temporarily fixed at four locations while maintaining the state in which the outer peripheral edge of the battery lid 219 is abutted against the inner circumference (open end edge) of the open end portion of the battery outer can 212. Temporarily fix at sites 241-244. After that, as shown in FIG. 9B, while moving the laser irradiation position from the predetermined welding start portion of the fitting portion 222 along the fitting portion 222, the lasers are sequentially output to perform the main welding. As a result, the outer peripheral edge of the battery lid 219 and the open end of the battery outer can 212 are joined to complete the sealing.

Further, Patent Document 2 is mentioned as a method of welding and sealing the battery lid of a sealed battery by laser welding. 10A and 10B are views showing a method of laser welding the conventional battery outer can 312 and the battery lid 319 described in Patent Document 2.

FIG. 10A is a perspective view of the upper part of the battery can, and FIG. 10B is a diagram illustrating a cross section of the BB'line. When fitting the battery lid 319 to the open end 323 of the battery outer can 312, the long side upper end 345 is positioned beyond the upper surface of the battery lid 319, and the long side upper end 345 is bent. After crimping, the lid is placed on the upper end portion 346 on the short side. Then, the upper end portion 345 on the long side side of the battery can is bent from the upper surface toward the center, the crimped portion is irradiated with the laser 304 from the upper surface and laser welded, and the battery on the upper end portion 346 on the short side side of the battery outer can 312 is formed. The mounting surface of the lid 319 is irradiated with the laser 304 from the side surface, welded and sealed.

Japanese Unexamined Patent Publication No. 8-315790 Japanese Unexamined Patent Publication No. 2001-167740

However, the laser welding described in Patent Document 1 has a problem that a poorly sealed portion of the laser welding may occur.

Further, the conventional configuration of Patent Document 2 is a prism-shaped sealed battery, and has a problem that it is not suitable for fitting a battery lid to a battery outer can.

The present invention solves the above-mentioned conventional problems, and is suitable for fitting the battery lid to the battery outer can when the battery lid of the sealed battery is welded and sealed, and a gap due to the misalignment of the battery lid. It is an object of the present invention to provide a method for manufacturing a sealed battery capable of suppressing the occurrence of the above-mentioned battery and preventing the occurrence of welding defects after welding.

In order to achieve the above object, the method for manufacturing a sealed battery according to one aspect of the present invention is:
In a method for manufacturing a sealed battery in which the opening of a battery outer can is sealed with a battery lid.
A step of preparing a battery lid having a diameter smaller than the inner diameter of the opening of the battery outer can, having an outer peripheral end bent in the thickness direction and having a hook portion inclined outward in the radial direction, in the opening.
By melting a part of the battery lid to form a first melting portion, the battery lid is distorted starting from the first melting portion, and the tip of the hook portion is attached to the inner wall of the battery outer can. The battery exterior is formed by forming a second melting portion that welds the hook portion of the battery lid and the open end portion of the battery exterior can, outside the step of moving toward the first melting portion and the first melting portion. The step of welding the can and the battery lid,
including.

As described above, according to the method for manufacturing a sealed battery of the present invention, when the battery lid of the sealed battery is welded and sealed, it is suitable for fitting the battery lid to the battery outer can, and the battery lid It is possible to prevent the generation of gaps due to misalignment and to prevent welding defects after welding.

The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure explaining the mathematical formula for explaining an example of the method of reducing the gap between the battery outer can and the battery lid of Embodiment 1 of this invention. The figure explaining the mathematical formula used for explaining an example of the method of reducing the gap between the battery outer can and the battery lid of Embodiment 1 of this invention. The figure explaining the example of the calculation result in the case of carrying out an example of the method of reducing the gap between the battery outer can and the battery cover of Embodiment 1 of this invention. The figure explaining the example of the calculation result in the case of carrying out an example of the method of reducing the gap between the battery outer can and the battery cover of Embodiment 1 of this invention. The figure explaining the example of the calculation result in the case of carrying out an example of the method of reducing the gap between the battery outer can and the battery cover of Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention. The figure explaining an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention when a battery cover is slantly inserted into a battery outer can. The figure explaining an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 1 of this invention when a battery cover is slantly inserted into a battery outer can. The figure explaining the mathematical formula used for explaining an example of the method of reducing the gap between the battery outer can and the battery lid of Embodiment 2 of this invention. The figure explaining the mathematical formula used for explaining an example of the method of reducing the gap between the battery outer can and the battery lid of Embodiment 2 of this invention. The figure explaining the example of the calculation result in the case of carrying out an example of the method of reducing the gap between the battery outer can and the battery cover of Embodiment 2 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 2 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 2 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 2 of this invention. The figure which shows an example of the process of the manufacturing method of the closed type battery which concerns on Embodiment 2 of this invention. The figure explaining the cylindrical sealed battery described in Patent Document 1. The figure explaining the problem at the time of sealing of the cylindrical closed-type battery described in Patent Document 1. The figure which shows the conventional method of fixing a battery outer can and a battery cover described in Patent Document 1. The figure which shows the conventional method of fixing a battery outer can and a battery cover described in Patent Document 1. The figure which shows the conventional method of fixing a battery outer can and a battery cover described in Patent Document 2. The figure which shows the conventional method of fixing a battery outer can and a battery cover described in Patent Document 2. The figure explaining the problem when the battery cover is tilted when the battery cover is fitted to the battery outer can. The figure explaining the problem when the battery cover is tilted when the battery cover is fitted to the battery outer can.

(Background to the present invention)
In the conventional configuration of temporarily fixing by laser welding of Patent Document 1, as shown in FIGS. 11A and 11B, the battery outer can 112 and the battery lid 119 are poorly fitted. For example, when the battery lid 119 is diagonally fitted as shown in FIG. 11A and temporarily welded as shown in FIG. 11B in this state, the battery outer can 112 and the battery lid 119 are annularly raised in a state where the laser 104 is out of focus. There may be a place where the portion 161 is temporarily welded, or a place where the portion 161 is temporarily welded with a gap 162 left. Since the temporary welding is usually performed with a weaker output than the main welding, if the temporary welding is performed in a state where the laser is out of focus or a gap 162 is left, the temporary welding is temporarily fixed with a weaker force than usual. When main welding is performed in this state, a part of the battery lid 119 jumps up due to the thermal deformation of the battery lid 119, the gap 162 of the fitting portion increases, and the parallelism deteriorates. As a result, there is a problem that a poorly sealed portion of laser welding may occur.

In order to suppress the above-mentioned diagonal fitting and the occurrence of the gap 162 between the battery outer can 112 and the battery lid 119, it is necessary to sufficiently manage the shape accuracy and the fitting accuracy of the battery outer can 112 and the battery lid 119. be.

Further, the welding conditions at the time of main welding are different between the temporarily welded portion and the portion not temporarily welded. Therefore, when the main welding is performed under the same welding conditions such as output, speed, and number of pulses, the temporary welding portion has less penetration of the main welding due to laser welding than the portion not temporarily welded. As a result, the temporary welded portion may become the starting point of the decrease in strength, or depending on the material, it may be welded twice, so that it may become the starting point of stress corrosion cracking.

Further, the conventional configuration of Patent Document 2 is a prism-shaped sealed battery, and has a problem that it is not suitable for fitting a battery lid to a battery outer can.

Therefore, the present inventors have conducted diligent studies in order to solve the above-mentioned conventional problems, and have reached the following inventions.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The method for manufacturing the sealed battery according to the first embodiment of the present invention will be described with reference to FIGS. 1A to 1D. 1A to 1D are cross-sectional views illustrating a method of correcting the gap 62 between the battery outer can 12 and the battery lid 19 and fixing the battery outer can 12 and the battery lid 19. The battery outer can 12 and the battery lid 19 are made of a metal such as aluminum, SUS, and iron, and the battery outer can 12 and the battery lid 19 are made of the same material. Iron is usually plated with Ni to prevent corrosion.

As shown in FIG. 1A, the battery lid 19 is a disk-shaped lid that seals the open end portion 23 of the bottomed cylindrical battery outer can 12. The battery lid 19 is provided with a hole in the center of the disk-shaped sealing plate 20, and the negative electrode terminal 14 is fixed to the hole via a gasket 21. The negative electrode terminal 14 is welded to the negative electrode tab terminal 13.

The battery lid 19 has a hook portion 70 in which the outer peripheral end portion of the sealing plate 20 is bent in the thickness direction and is inclined outward in the radial direction. The battery lid 19 has a hook portion 70 formed so that the outer peripheral end portion of the battery lid 19 is bent toward the lower surface side of the battery lid 19 and extends outward in the radial direction. The hook portion 70 is formed by an annular raising portion 71 provided in an annular shape along the outer peripheral end portion of the sealing plate 20. The annular lowering portion 71 extends toward the lower surface side (downward) of the battery lid 19 at the outer peripheral end portion of the sealing plate 20, and extends in a direction extending outward in the radial direction of the battery lid 19.

The diameter of the battery lid 19 is 0.1 to 0.5 mm shorter than the inner diameter of the opening 10 of the battery outer can 12. Therefore, when the battery lid 19 is arranged in the opening 10 of the battery outer can 12, a gap 62 is formed between the battery lid 19 and the battery outer can 12.

In FIG. 1A, the battery lid 19 is prepared in the opening 10 of the battery outer can 12 so that the tip of the hook portion 70, that is, the tip of the annular raising portion 71 faces downward. Specifically, the battery lid 19 is arranged in the opening 10 of the battery outer can 12.

In FIG. 1B, a laser 4 having an output enough to melt the surface of the battery lid 19 is irradiated to a position on the upper surface portion of the battery lid 19 and on the inner peripheral portion side of the outer peripheral portion thereof. Specifically, the laser 4 is irradiated to the surface of the battery cover 19 at a position separated from the center of the battery cover 19 in the radial direction by a predetermined distance. The position separated by a predetermined distance may be a position between the center of the battery lid 19 and the outer peripheral end of the battery lid 19.

The surface of the portion irradiated with the laser 4 is melted, and then cooled and solidified. At this time, as shown in FIG. 1B, a strain starting point 72a is generated at the stage of melting and solidification. The strain origin point 72a is a portion where distortion is generated by melting and solidifying a part of the surface of the battery lid 19 in the laser-irradiated portion. In this specification, the strain starting point may be referred to as a first melting portion.

In the battery lid 19, warpage occurs starting from the distortion starting point 72a, which is the portion irradiated with the laser. The warp is corrected so that the gap 62 is reduced.

Specifically, the battery lid 19 is distorted starting from the distortion starting point 72a, and the battery lid 19 is bent upward. That is, the battery lid 19 bends toward the upper surface side of the battery lid 19, and the tip of the annular lowering portion 71 shifts upward (lifts). As a result, the tip of the annular lowering portion 71 moves toward the inner wall of the battery outer can 12, and the radius of the battery lid 19 (the center of the battery lid 19) at the portion where the warp occurs starting from the strain starting point 72a. The length from the battery lid 19 to the outer peripheral end portion) becomes larger. As a result, the gap 62 between the battery lid 19 and the battery outer can 12 can be reduced or eliminated on the side where the strain starting point 72a is formed.

Next, in FIG. 1C, the strain origin point 72b is formed on the side opposite to the side where the strain origin point 72a is formed with respect to the center of the battery lid 19. Specifically, the strain origin point 72b is formed on a line segment connecting the strain origin point 72a and the center of the battery lid 19 extending from the center of the battery lid 19 to the side opposite to the side where the strain origin point 72a is formed. .. The strain origin point 72b is formed in the same manner as the strain origin point 72a. That is, the strain origin point 72b is formed by irradiating the surface of the battery lid 19 with the laser 4 at a position separated from the center of the battery lid 19 in the radial direction by a predetermined distance.

As shown in FIG. 1C, the battery lid 19 is distorted starting from the strain starting point 72b, and the battery lid 19 is bent so as to lift the tip of the annular raising portion 71 provided at the outer peripheral end portion of the battery lid 19. As a result, the battery lid 19 is warped upward from the strain starting point 72b, and the tip of the annular raising portion 71 is directed to the radial outside of the battery lid 19, that is, toward the inner wall of the battery outer can 12 at the portion where the warp occurs. Since it moves, the radius of the battery lid 19 becomes large. As a result, the gap 62 between the battery lid 19 and the battery outer can 12 can be reduced on the side where the strain starting point 72b is formed.

By forming the strain starting points 72a and 72b on the upper surface of the battery lid 19 in this way, the radius of the battery lid 19 is increased, so that the gap 62 between the battery outer can 12 and the battery lid 19 is reduced, or the gap is reduced. 62 can be eliminated.

In FIGS. 1B and 1C, the position where the laser 4 is irradiated, that is, the position where the strain starting points 72a and 72b are formed can be changed depending on the size of the gap 62. Further, the amount of strain can be changed by the output of the laser, and as the laser output is increased and the amount of melting is increased, the amount of strain is also increased.

Next, in FIG. 1D, the laser 4 is irradiated to the outside of the strain starting points 72a and 72b, respectively, to form the strain starting points 73a and 73b, respectively. Specifically, the strain starting point 73a is formed at a position separated by a predetermined distance from the strain starting point 72a toward the outer side in the radial direction of the battery lid 19. Further, the strain starting point 73b is formed at a position separated from the strain starting point 72b toward the outer side in the radial direction of the battery lid 19 by a predetermined distance. By distorting the battery lid 19 with the strain starting points 73a and 73b as starting points, the battery lid 19 is bent upward, and the tip of the annular raising portion 71, which is the outer peripheral end of the battery lid 19, is lifted. As a result, the tip of the annular lowering portion 71 moves toward the inner wall of the battery outer can 12, and the radius of the battery lid 19 is further increased at the portion where the warp occurs starting from the distortion starting points 73a and 73b. As a result, the tip of the annular lowering portion 71 comes into contact with the inner wall of the battery outer can 12, so that the gap 62 can be eliminated and the battery lid 19 can be more firmly fixed to the open end 23 of the battery outer can 12. ..

In the first embodiment, an example of forming the strain starting points 72a, 72b, 73a and 73b has been described, but the present invention is not limited to this. For example, in the correction method for reducing the gap 62, the strain starting points 72a and 72b may be formed, and the strain starting points 73a and 73b may not be formed.

A method of correcting the gap 62 to be small will be described in detail with reference to FIGS. 2A to 2E. 2A and 2B show the cross-sectional structure of the battery outer can 12 and the battery lid 19, and are views schematically showing a part of the battery lid 19 on the outer side in the radial direction from the center. In FIGS. 2A to 2E, an example in which the strain starting point 72a is formed will be described.

In FIGS. 2A and 2B, the length of the first portion 81 from the center of the battery lid 19 to the strain starting point 72 is L ₁ , and the length of the second portion 82 from the strain starting point 72 to the annular lowering portion 71 is L _2. , the length of the annular upright lowered portion 71 and _{L 3.} With the strain origin point 72a as a reference, the angle formed by the first portion 81 and the second portion 82 is θ ₂ , and the angle formed by the second portion 82 and the annular lowering portion 71 is θ ₃ . Further, the distance from the center of the battery lid 19 to the inner wall of the battery outer can 12 is R.

Assuming that the distance from the center of the battery lid 19 to the end of the annular lowering portion 71 is B in the state before irradiating the laser 4 in FIG. 2A, the following mathematical formula holds in FIG. 2A.

In the present invention, B <R from the fitting of the battery lid 19 and the battery outer can 12 in the state before irradiating the laser 4 of FIG. 2A. That is, before the laser 4 is irradiated, the dimension (diameter) of the battery lid 19 is smaller than the opening dimension (inner diameter) of the opening 10 of the battery outer can 12. As a result, the battery lid 19 can be easily arranged in the opening 10 of the battery outer can 12 in the state before the battery lid 19 and the battery outer can 12 are welded.

Next, as shown in FIG. 2B, the battery lid 19 is distorted starting from the distortion starting point 72a, which is the portion irradiated with the laser 4, and the tip (lower end) of the annular lowering portion 71 of the battery lid 19 is the battery outer can 12 The radius of the battery lid 19 is increased by moving the battery lid 19 toward the inner wall of the battery lid 19. Assuming that the distance from the center of the battery lid 19 to the tip of the annular lowering portion 71 in the state after irradiating the laser 4 is A, the following formula holds.

In the present invention, A> R in the state after irradiating the laser 4 of FIG. 2B. That is, by setting the diameter of the battery lid 19 to be larger than the inner diameter of the battery outer can 12, the gap 62 between the outer peripheral end of the battery lid 19 and the inner wall of the battery outer can 12 can be eliminated.

In this way, when the above equations (1) and (2) are satisfied, after the battery lid 19 is arranged in the opening 10 of the battery outer can 12, the gap 62 is reduced or the gap 62 is eliminated, and the battery outer can The battery lid 19 can be firmly fixed to the open end portion 23 of 12.

_{The results of some simulations of L 1} , L ₂ , L ₃ , θ ₂ , and θ ₃ for which the mathematical formulas (1) and (2) hold are shown in FIGS. 2C, 2D, and 2E. _{The values of R, L 1} , L ₂ , L ₃ , L ₄ , θ ₂ , and θ ₃ shown in FIGS. 2C to 2E are examples and are not limited to these values.

FIG. 2C shows a simulation result of whether or not A> R is satisfied when the _{angle θ 2} formed by the first portion 81 and the second portion 82 is changed as a parameter. As shown in FIG. 2C, the simulation conditions were R = 10 mm, L ₁ = 6 mm, L ₂ = 3 mm, L ₃ = 3 mm, and θ ₃ = 80 °. According to the mathematical formula (1), B = 9.521 mm, and B <R. Further, θ ₂ was changed by 2 ° at 2 ° or more and 20 ° or less.

In the simulation result shown in FIG. 2C, the distance A increases as the angle of _{θ 2 increases.} That is, as _{the angle of θ 2} increases, the gap (RB) between the battery lid 19 and the battery outer can 12 becomes smaller. Further, when _{the angle of θ 2} becomes 12 ° or more, A> R.

FIG. 2D shows a simulation result when the _{length of L 1} is increased and L ₂ is shortened as compared with the simulation conditions shown in FIG. 2C. The simulation conditions in FIG. 8D were L ₁ = 8 mm and L ₂ = 1 mm. The other simulation conditions in FIG. 2D are the same as those shown in FIG. 2C except for _{L 1} and L _2.

Also in the simulation result shown in FIG. 2D, as _{the angle of θ 2} increases, the distance A increases and the gap (RB) between the battery lid 19 and the battery outer can 12 decreases. Further, when _{the angle of θ 2} becomes 10 ° or more, A> R.

In the simulation results shown in FIGS. 2C and 2D, the gap (RB) between the battery lid 19 and the battery outer can 12 is 0.479 mm, which is the same before the laser 4 is irradiated. _{When the angle of θ 2} is generated at the strain origin point 72a by irradiating the laser 4, the distance A becomes large and the gap (RB) becomes small. The _{larger the angle of θ 2,} the larger the distance A and the smaller the gap (RB). Then, when the size of the distance A exceeds R = 10 mm, the gap (RB) disappears completely. The amount of strain (angle θ ₂ ) can be controlled by the amount of melting on the surface of the battery lid 19 at the strain origin point 72a. The amount of melting can be controlled by, for example, the output of the laser 4.

FIG. 2E shows a simulation result when the angle of _{θ 3} is reduced as compared with the simulation conditions shown in FIG. 2D. The simulation condition in FIG. 2E was θ ₃ = 75 °. The other simulation conditions in FIG. 2E are the same as those shown in FIG. 2D except for _{θ 3.}

Also in the simulation result shown in FIG. 2E, as _{the angle of θ 2} increases, the distance A increases and the gap (RB) between the battery lid 19 and the battery outer can 12 decreases. Further, when _{the angle of θ 2} becomes 6 ° or more, A> R. That is, when θ ₃ is small, A> R even when the angle of θ 2 is small (the amount of distortion is small).

3A to 3G are top views of the battery lid 19 and the battery outer can 12 for explaining the first embodiment of the present invention, and are views for supplementarily explaining the correction method of FIGS. 1A to 1D. In FIGS. 3A to 3D, hatching is provided at the portion of the gap 62 in order to make the gap 62 easy to see. Further, in FIGS. 3C to 3G, hatching is attached to the distortion starting points 72 and 73. Further, in FIG. 3G, the welded portion 94 is hatched.

The gap 62 between the battery outer can 12 of FIG. 3A and the annular raising portion 71 located on the outer peripheral portion of the battery lid 19 is corrected. In FIG. 3B, the strain origin point 72a is formed by laser irradiation.

Specifically, the battery lid 19 is distorted starting from the distortion starting point 72a, and the battery lid 19 is bent upward. As a result, the battery lid 19 is warped by lifting the tip (lower end) of the annular raising portion 71, which is the outer peripheral end portion of the battery lid 19. At the portion where the warp occurs, the radius of the battery lid 19 (the length from the center of the battery lid 19 to the outer peripheral end of the battery lid 19) becomes large. That is, the radius of the battery cover 19 in the direction from the center of the battery cover 19 to the strain starting point 72a becomes large. As a result, the gap 62 can be reduced.

In FIG. 3B, when there is a gap 62 other than the portion where the strain origin point 72a is formed with respect to the center of the battery lid 19, the strain origin point is formed and the gap 62 is further reduced as in the description of FIGS. 1A to 1D. Correct as follows.

As shown in FIG. 3C, the strain origin point 72b is formed on the opposite side of the strain origin point 72a with reference to the center of the battery lid 19. At this time, the radius of the battery lid 19 on the side where the strain starting point 72b is formed increases due to the warp of the battery lid 19 generated from the strain starting point 72b. As a result, the gap 62 on the side where the strain starting point 72b is formed can be reduced.

Further, as shown in FIG. 3D, by forming the strain starting points 72c and 72d at positions different from the strain starting points 72a and 72b, the gap 62 is corrected to be small. For example, as shown in FIG. 3D, the strain origin points 72a and 72b are formed side by side in the X direction with the center of the battery cover 19 interposed therebetween, whereas the strain origin points 72c and 72d are arranged side by side in the Y direction orthogonal to the X direction. It is formed.

Further, as shown in FIG. 3E, the strain starting point 72 is continuously formed on the upper surface of the battery lid 19 until the gap 62 disappears. In FIG. 3E, the strain origin points 72a, 72b, 72c and 72d are shown as strain origin points 72. In the first embodiment, the plurality of strain origin points 72 are formed on concentric circles centered on the center of the battery lid 19. In other words, the plurality of strain origin points 72 have the same distance to the center of the battery lid 19. Further, the plurality of strain origin points 72 are formed at positions shifted by 45 ° from the center of the battery lid 19 as the center of rotation.

Further, as shown in FIG. 3F, the battery outer can 12 and the battery lid 19 are firmly fixed by forming the plurality of strain origin points 73 on the outside of the plurality of strain origin points 72. In the first embodiment, the number of the plurality of strain origins 73 is formed larger than the number of the plurality of strain origins 72. In the example shown in FIG. 3F, the number of the plurality of strain origin points 72 is eight, while the number of the plurality of strain origin points 73 is 16. The plurality of strain origin points 73 are formed on concentric circles centered on the center of the battery lid 19, similarly to the plurality of strain origin points 72. The plurality of strain origin points 73 are formed at positions shifted by 22.5 ° with respect to the center of the battery lid 19 as the center of rotation.

Finally, as shown in FIG. 3G, a welded portion 94 for welding the open end portion 23 of the battery outer can 12 and the hook portion 70 of the battery lid 19 is formed. By forming the welded portion 94, the battery outer can 12 and the battery lid 19 can be welded and the battery outer can 12 can be sealed. In this specification, the welded portion 94 may be referred to as a second molten portion.

4A and 4B are cross-sectional views for explaining the first embodiment of the present invention, and are views for explaining the correction of the gap 62 when the battery lid 19 is obliquely fitted. In FIGS. 4A and 4B, the battery lid 19 is fitted in the opening 10 of the battery outer can 12 in a slanted state. In this state, the annular raising portion 71 located on the lower side than the center of the battery lid 19 is in contact with the inner wall of the battery outer can 12, and the annular raising portion 71 located on the higher side than the center of the battery lid 19. A gap 62 is formed between the battery outer can 12 and the inner wall of the battery outer can 12.

Similar to the description of FIGS. 1A to 1D, as shown in FIG. 4A, the strain origin point 72 is formed by irradiating the upper surface of the battery lid 19 located on the lower side than the center of the battery lid 19 with the laser 4. As a result, as shown in FIG. 4B, the battery lid 19 is distorted and bent starting from the strain starting point 72, so that the annular raising portion 71 located higher than the center of the battery lid 19 can be lowered. Thereby, the gap 62 can be reduced or eliminated.

In FIG. 4B, when the gap 62 remains, strain starting points 72 and 73 are further formed and the gap 62 is further corrected in the same manner as in the description of FIGS. 1A to 1D. By repeating this, the gap 62 can be eliminated even when the battery lid 19 is inserted obliquely with respect to the opening 10 of the battery outer can 12. As a result, the battery lid 19 and the battery outer can 12 can be welded with high precision, and a highly reliable sealing can be realized.

As described above, in the method for manufacturing a sealed battery of the present invention, the battery lid 19 having a diameter smaller than the inner diameter of the opening 10 of the battery outer can 12 is arranged in the opening 10 of the battery outer can 12. After that, the strain starting point 72 (first melting portion) is formed on the upper surface of the battery lid 19 to distort the battery lid 19 and bend the battery lid 19 toward the upper surface side of the battery lid 19 in the thickness direction. As a result, the tip of the annular lowering portion 71 can be moved toward the inner wall of the battery outer can 12, and the radius of the battery lid 19 on the side where the strain starting point 72 is formed can be increased. As a result, the gap 62 between the battery lid 19 and the battery outer can 12 can be reduced or eliminated on the side where the strain starting point 72 is formed.

Further, by moving the tip of the annular raising portion 71 toward the inner wall of the battery outer can 12, the annular raising portion 71 of the battery lid 19 can be brought into contact with the inner wall of the battery outer can 12. As a result, the battery lid 19 can be firmly fixed in the opening 10 of the battery outer can 12. As a result, even if the battery lid 19 is not temporarily fixed to the open end portion 23 of the battery outer can 12, for example, a welded portion 94 (second melting portion) is formed by laser welding, and the battery outer can 12 is formed. The opening 10 can be sealed.

Therefore, according to the method for manufacturing a sealed battery according to the first embodiment of the present invention, the battery lid 19 is suitable for fitting to the battery outer can, the generation of a gap due to the misalignment of the battery lid 19 is suppressed, and the generation of a gap is suppressed. , It is possible to manufacture a sealed battery in which welding defects after welding are unlikely to occur.

In the first embodiment, an example in which the strain starting points 72 and 73 and the welded portion 94 are formed by the laser 4 has been described, but the present invention is not limited to this. The strain origin points 72 and 73 and the welded portion 94 may be formed by any means capable of melting the upper surface of the battery lid 19.

In the first embodiment, in FIGS. 3A to 3G, examples in which the strain starting points 72 and 73 are formed concentrically at equal intervals around the center of the battery lid 19 have been described, but the present invention is not limited thereto. The strain starting points 72 and 73 may be formed on the upper surface of the battery lid 19.

(Embodiment 2)
The method for manufacturing the sealed battery according to the second embodiment of the present invention will be described with reference to FIGS. 5A to 5C. Specifically, a method of reducing the gap 62 between the battery lid 19a and the battery outer can 12 will be described in detail with reference to FIGS. 5A to 5C.

In the second embodiment, the points different from the first embodiment will be mainly described. In the second embodiment, the same or equivalent configurations as those in the first embodiment will be described with the same reference numerals. Further, in the second embodiment, the description overlapping with the first embodiment is omitted.

In the second embodiment, the battery lid 19a has an inclined portion 83 that is inclined downward, and the hook portion 70a is formed by bending the outer peripheral end portion of the battery lid 19a upward. Different from.

5A and 5B show the cross-sectional structure of the battery outer can 12 and the battery lid 19a, and is a diagram schematically showing a part of the battery lid 19a on the outer side in the radial direction from the center. In FIGS. 5A to 5C, an example in which the strain starting point 72 is formed will be described.

As shown in FIG. 5A, in the second embodiment, the battery lid 19a has a flat first portion 81 and a second portion 82, an inclined portion 83, and an annular rising portion 84. In this specification, the first portion 81 and the second portion 82 may be referred to as a flat portion.

In the second embodiment, the first portion 81 and the second portion 82 constituting the flat portion are flat portions extending radially outward from the center of the battery lid 19a.

The inclined portion 83 is formed by bending a disk-shaped sealing plate 20 toward the lower surface side of the battery lid 19a inside the hook portion 70a, that is, the annular rising portion 84. Specifically, the inclined portion 83 extends downwardly inclined from the second portion 82 (flat portion) and is connected to the hook portion 70a. The inclined portion 83 is inclined with an _{angle θ 3} with respect to the extending direction of the second portion 82.

In the second embodiment, the hook portion 70a is formed by bending the outer peripheral end portion of the battery lid 19a toward the upper surface side of the battery lid 19a. Specifically, the hook portion 70a is formed by an annular rising portion 84 provided in an annular shape along the end portion of the inclined portion 83. The annular rising portion 84 extends upward and extends in a direction extending outward in the radial direction of the battery lid 19. _{The annular rising portion 84 has an angle θ 4} with respect to the extending direction of the inclined portion 83 and extends upward.

In FIG. 5A, the battery lid 19a is prepared in the opening 10 so that the tip of 70a, that is, the tip of the annular rising portion 84 faces upward. Specifically, the battery lid 19a is arranged in the opening 10 of the battery outer can 12.

5A and 5B show the cross-sectional structure of the battery outer can 12 and the battery lid 19a, and is a diagram schematically showing a part of the battery lid 19a on the outer side in the radial direction from the center. In FIGS. 5A and 5B, the battery lid 19a has an annular inclined portion 83 and an annular rising portion 84.

In the second embodiment, as shown in FIG. 5A, the distance of the first portion 81 from the center of the battery lid 19 to the strain starting point 72 is L ₁ , and the distance of the second portion 82 from the strain starting point 72 to the inclined portion 83 is set. Let L ₂ and the length of the inclined portion 83 be L ₃ . With reference to the strain origin point 72, the angle formed by the first portion 81 and the second portion 82 is θ ₂ , the angle formed by the second portion 82 and the inclined portion 83 is θ ₃ , and the inclined portion 83 and the annular rising portion 84 are formed. Let θ ₄ be the angle between the two. Further, the distance from the center of the battery lid 19a to the battery outer can 12 is R.

Assuming that the distance from the center of the battery lid 19a to the end of the annular rising portion 84 is B in the state before irradiating the laser 4 of FIG. 5A, the following formula holds.

In the present invention, in the state before the battery lid 19a and the battery outer can 12 are welded, B <R because the battery lid 19a and the battery outer can 12 are fitted together. As a result, the battery lid 19a can be easily arranged in the opening 10 of the battery outer can 12.

Next, as shown in FIG. 5B, the strain origin point 72 is formed by irradiating the upper surface of the battery lid 19a with the laser 4. At this time, by distorting the second portion 82 starting from the distortion starting point 72, the second portion 82 is bent upward from the battery lid 19a. As a result, the inclined portion 83 shifts upward, and the tip of the annular rising portion 84 moves toward the inner wall of the battery outer can 12.

Assuming that the distance from the center of the battery lid 19 to the end of the annular lowering portion 71 in the state after irradiating the laser 4 in FIG. 5B is A, the following mathematical formula holds.

In the present invention, A> R in the state after irradiating the laser 4 of FIG. 5B. That is, when the diameter of the battery lid 19a is larger than the inner diameter of the battery outer can 12, the gap 62 between the outer peripheral end of the battery lid 19a and the inner wall of the battery outer can 12 can be eliminated.

In this way, when the above equations (3) and (4) are satisfied, after the battery lid 19a is arranged in the opening 10 of the battery outer can 12, the gap 62 is eliminated and the opening end 23 of the battery outer can 12 is eliminated. The battery lid 19a can be firmly fixed to the surface.

FIG. 5C shows the results of simulations for _{L 1} , L ₂ , L ₃ , L ₄ , θ ₂ , θ ₃ , and θ _4, for which mathematical formulas (3) and (4) hold. _{The values of R, L 1} , L ₂ , L ₃ , L ₄ , θ ₂ , θ ₃ , and θ ₄ shown in FIG. 5C are examples and are not limited to these values.

FIG. 5C shows a simulation result of whether or not A> R is satisfied when the _{angle θ 2} formed by the first portion 81 and the second portion 82 is changed as a parameter. As shown in FIG. 5C, the simulation conditions were R = 10 mm, L ₁ = 3 mm, L ₂ = 3 mm, L ₃ = 3.4 mm, θ ₃ = 10 °, and θ ₄ = 85 °. According to the mathematical formula (1), B = 9.866 mm, and B <R. Further, θ ₂ was changed by 1 ° at 1 ° or more and 10 ° or less.

In the simulation result shown in FIG. 5C, the distance A increases as the angle of _{θ 2 increases.} That is, as _{the angle of θ 2} increases, the gap (RB) between the battery lid 19a and the battery outer can 12 becomes smaller. Further, when _{the angle of θ 2} becomes 4 ° or more, A> R.

In the second embodiment as in the first embodiment, the strain amount (angle θ ₂ ) can be controlled by the amount of melting of the surface of the battery lid 19a at the strain origin point 72a. The amount of melting can be controlled by, for example, the output of the laser 4.

By designing as described above, the gap 62 is corrected so as to be small or eliminated, high-precision welding becomes possible, and a highly reliable sealing is realized.

A method of correcting the gap 62 between the battery outer can 12 and the battery lid 19 and fixing the battery outer can 12 and the battery lid 19a will be described with reference to FIGS. 6A to 6D. 6A to 6D are top views of the battery lid 19a and the battery outer can 12. In FIGS. 6A to 6D, hatching is provided at the portion of the gap 62 in order to make the gap 62 easy to see. Further, in FIGS. 6B to 6D, hatching is attached to the distortion starting points 72 and 73.

As shown in FIG. 6A, the battery lid 19a is arranged in the opening 10 of the battery outer can 12.

As shown in FIG. 6B, the strain origin point 72 is formed by irradiating the upper surface of the battery lid 19a with the laser 4. At this time, by distorting the battery lid 19a starting from the distortion starting point 72, the inclined portion 83 of the battery lid 19a shifts upward. As a result, the tip of the annular rising portion 84 moves toward the inner wall of the battery outer can 12, and the radius of the battery lid 19a on the side where the strain starting point 72 is formed increases. As a result, the gap 62 can be reduced.

In FIG. 6B, when the amount of correction of the gap 62 by the distortion origin 72 is small, it is possible to form the distortion origin and further reduce the gap 62. For example, as shown in FIG. 6C, the strain origin 73a may be formed at a position outside the strain origin 72.

Further, in order to further reduce the gap 62, as shown in FIG. 6D, the strain origin point 73b may be formed on the side opposite to the side where the strain origin points 72 and 73a are formed with respect to the battery lid 19a. ..

As described above, also in the second embodiment, the radius of the battery lid 19a on the strain starting points 72 and 73 side is increased by forming the strain starting points 72 and 73 on the upper surface of the battery lid 19a as in the first embodiment. can do. Thereby, the gap 62 can be reduced or eliminated. Further, the battery lid 19a can be firmly fixed in the opening 10 of the battery outer can 12.

That is, according to the method for manufacturing a sealed battery according to the second embodiment of the present invention, it is suitable for fitting the battery lid to the battery outer can 12, and the generation of the gap 62 due to the misalignment of the battery lid 19a is suppressed. Moreover, it is possible to manufacture a sealed battery in which welding defects are less likely to occur after welding.

The sealing of the sealed battery of the present invention is a cylindrical battery formed by welding a battery lid to the opening of the battery outer can, and the opening edge of the battery outer can and the edge of the battery lid are surely melted. Therefore, a welded portion having sufficient strength and high sealing property can be formed with high productivity, which is useful for stable use of a lithium thionyl chloride battery, a lithium manganese dioxide battery, a lithium ion battery, etc. for a long period of time. ..

4 Laser 10 Opening 11 Positive electrode tab terminal 12 Battery outer can 13 Negative electrode tab terminal 14 Negative electrode terminal 15 Positive electrode plate 16 Negative electrode plate 17 Electrode winding product 18 Separator 19, 19a Battery cover 20 Seal plate 21 Gasket 22 Fitting part
23 Opening end 62 Gap 70, 70a Hook 71 Circular rising part 72, 72a, 72b, 72c, 72d Strain starting point 73, 73a, 73b Strain starting point 81 First part 82 Second part 83 Inclined part 84 Ring rising part 94 Welded part 104 Laser 110 Opening part 111 Positive electrode tab terminal 112 Battery outer can 113 Negative electrode tab terminal 114 Negative electrode terminal 115 Positive electrode plate 116 Negative electrode plate 117 Electrode winding product 118 Separator 119 Battery lid 120 Sealing plate 121 Gasket 122 Fitting part 123 Opening End 161 Circular riser 162 Gap 212 Battery outer can 219 Battery lid 222 Fitting part 241,242,243,244 Temporary fixing part 312 Battery outer can 323 Open end 319 Battery lid 304 Laser 345 Long side upper end 346 Upper end on the short side

Claims (3)

In a method for manufacturing a sealed battery in which the opening of a battery outer can is sealed with a battery lid.
A battery cover to have a hook that is inclined radially outward with bending the outer peripheral end portion in the thickness direction, the distance from the center of the battery cover to the end portion of the hook from the center of the battery cover A step of preparing the battery lid in the opening, which is smaller than the distance to the inner wall of the battery outer can.
By melting a part of the battery lid to form a first molten portion, the hook portion side of the battery lid is distorted toward the first molten portion side with the first molten portion as a starting point. The step of moving the tip of the hook portion toward the inner wall of the battery outer can, and outside the first melting portion, the hook portion of the battery lid and the open end portion of the battery outer can are welded. A step of welding the battery outer can and the battery lid by forming a second molten portion,
A method for manufacturing a sealed battery, including. The hook portion is formed by bending the outer peripheral end portion of the battery lid toward the lower surface side of the battery lid.
The method for manufacturing a sealed battery according to claim 1. The battery lid has an inclined portion formed by bending on the lower surface side of the battery lid inside the hook portion.
The hook portion is formed by bending the outer peripheral end portion of the battery lid toward the upper surface side of the battery lid.
The step of moving the tip of the hook portion toward the inner wall of the battery outer can includes forming the first melting portion on the upper surface of the battery lid inside the inclined portion.
The method for manufacturing a sealed battery according to claim 1.

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