JP6608787B2 - Manufacturing method of sealed battery - Google Patents

Description

  The present invention relates to a method for manufacturing a sealed battery.

  Conventionally, for example, in a sealed battery for large current charge / discharge applications used as a power source for an electric vehicle, a stationary power supply device, etc., a battery case in which an electrode group in which positive and negative electrodes are arranged via a separator is infiltrated with an electrolyte. Is housed inside. As such an electrode group, a wound electrode group in which a positive electrode and a negative electrode are wound via a separator, and a stacked electrode group in which a positive electrode and a negative electrode are stacked via a separator are widely known.

  By the way, the battery case is generally provided with a liquid injection port for injecting an electrolyte solution, and the sealed battery has a sealed structure in which the liquid injection port is sealed with a sealing plug after the electrolyte solution is injected. Has been adopted. In Patent Document 1, in the above-described sealed battery, the inside of the case is hermetically sealed by welding a sealing plug and a battery case, which are arranged so as to close the liquid injection port. It is described that the sealing in the battery case becomes incomplete due to poor welding caused by the electrolytic solution adhering to the liquid injection port when the two are welded.

  In Patent Document 1, as means for solving the above-described problem, welding is performed at least twice on the entire circumference of the boundary portion between the battery case and the sealing plug, and the at least two weldings are performed in a predetermined manner. Disclosed is a method for manufacturing a sealed battery, which is performed at intervals of time. The total of the predetermined time intervals is a time required for the electrolytic solution vaporized when welding the boundary portion between the lid portion and the sealing plug portion in the welding process to be discharged to the outside of the battery case. Some are preferred. Patent Document 1 describes that the manufacturing method can suppress poor welding that occurs when sealing by laser welding.

Japanese Patent Laying-Open No. 2015-219962

  When the boundary portion between the lid portion and the sealing plug portion is laser-welded, the welded portion contracts, so that a gap is generated at the boundary portion between the unwelded lid portion and the sealing plug portion. There is. According to Patent Document 1, since laser welding is performed in two steps with a predetermined time interval, the unwelded lid portion and the sealing plug are caused by cooling shrinkage of the welded portion. A gap is likely to occur at the boundary with the part. Therefore, poor welding occurs in the unwelded portion, and it is difficult to ensure sealing performance.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for manufacturing a sealed battery capable of suppressing poor welding and ensuring high sealing performance.

  In order to achieve the above object, a sealed battery of the present invention is a method for producing a sealed battery comprising a battery case having a liquid inlet and a sealing plug for sealing the liquid inlet, A liquid injection step of injecting an electrolyte into the battery case from the liquid injection port; and after the liquid injection step, the liquid injection port is closed with the sealing plug between the battery case and the sealing plug. A welding step of continuously welding the annular boundary portion to be formed along the boundary portion to seal the liquid injection port, and in the welding step, a plurality of parts set evenly in the boundary portion Welding is started simultaneously in the same direction along the boundary portion from the welding start position.

  According to the present invention, it is possible to obtain a sealed battery capable of suppressing poor welding and ensuring high sealing performance. Further features related to the present invention will become apparent from the description of the present specification and the accompanying drawings. Further, problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an external perspective view of a sealed battery according to Embodiment 1. FIG. FIG. 2 is an exploded perspective view of the sealed battery shown in FIG. 1. FIG. 3 is an exploded perspective view of a wound electrode group of the sealed battery shown in FIG. 2. The top view which expands and shows the principal part of a sealed battery. AA line sectional view of Drawing 4. The figure explaining another Example. The figure explaining another Example. FIG. 4 is an enlarged plan view showing a main part of a sealed battery according to a second embodiment.

  Embodiments of the method for manufacturing a sealed battery according to the present invention will be described below with reference to the drawings.

[Embodiment 1]
First, the configuration of the sealed battery according to the present embodiment will be described. FIG. 1 is an external perspective view of a sealed battery 100 according to the first embodiment. FIG. 2 is an exploded perspective view of the sealed battery 100 shown in FIG. 3 is an exploded perspective view of the wound electrode group 3 of the sealed battery 100 shown in FIG.

  The sealed battery 100 of the present embodiment is a sealed battery for large current charge / discharge applications that is used as a power source for an electric vehicle, a stationary power supply device, or the like. Although details will be described later, the sealed battery 100 of the present embodiment has at least two welding start positions in the joint region between the battery lid 6 and the sealing plug 11, and the welding start positions are the battery lid 6. Are arranged in the joining region where the welding perimeters are equal to the total welding perimeter of the sealing plug 11, and welding is started simultaneously from each welding start position.

  The sealed battery 100 of the present embodiment mainly includes a flat rectangular battery case, a positive electrode external terminal 14 and a negative electrode external terminal 12 provided outside the battery case, and a wound electrode housed in the battery case. And a positive electrode current collector plate 42 and a negative electrode current collector plate 22 that connect the wound electrode group 3 to the positive electrode external terminal 14 and the negative electrode external terminal 12. The positive electrode external terminal 14 and the negative electrode external terminal 12, the wound electrode group 3, and the positive electrode current collector plate 42 and the negative electrode current collector plate 22 are respectively attached to the battery case by the gasket 5, the insulating plate 7, and the insulating protective film 2. Are electrically insulated.

  The battery case, the positive electrode external terminal 14 and the positive electrode current collector plate 42 can be made of, for example, an aluminum alloy. Moreover, the negative electrode external terminal 12 and the negative electrode current collector plate 22 can be made of, for example, a copper alloy. In addition, the gasket 5 and the insulating plate 7 can be made of an insulating resin material such as polybutylene terephthalate, polyphenylene sulfide, or perfluoroalkoxy fluororesin. The insulating protective film 2 can be manufactured by a sheet of a synthetic resin such as PP (polypropylene) or a plurality of film members.

  The sealed battery 100 according to this embodiment includes a positive electrode side and a negative electrode side, for example, a positive electrode external terminal 14 and a negative electrode external terminal 12, and a positive electrode current collector plate 42 and a negative electrode current collector plate 22. It has a configuration that is generally in contrast to the centerline at W. Therefore, in the following, regarding the configuration common to the positive electrode side and the negative electrode side, the positive electrode external terminal 14 and the negative electrode external terminal 12 are collectively referred to as the external terminal 20, and the positive electrode current collector plate 42 and the negative electrode current collector plate 22 are collectively illustrated. The current collector plate 40 will be described.

  The battery case includes a flat rectangular battery can 1 having an opening 1 a at the top, and a rectangular flat battery cover 6 that seals the opening 1 a of the battery can 1. The battery can 1 has a generally rectangular bottom surface 1d, a generally rectangular wide side surface 1b and a narrow side surface 1c rising vertically from the bottom surface, and an upper portion is opened to have a generally rectangular opening 1a. The battery can 1 is welded and sealed so that the battery lid 6 closes the opening 1a in a state where the wound electrode group 3 is accommodated therein.

  The battery lid 6 has a substantially rectangular upper surface with the width direction of the sealed battery 100 as the longitudinal direction. A positive external terminal 14 and a negative external terminal 12 are provided at one end and the other end in the longitudinal direction of the upper surface of the battery lid 6. The battery cover 6 has through holes 26 and 46 through which the columnar connection portions 12a and 14a of the external terminal 20 are inserted at one end and the other end in the longitudinal direction of the upper surface, respectively, and the external terminal 20 is formed by the gasket 5 and the insulating plate 7. In addition, the current collector plate 40 is electrically insulated.

A gas discharge valve 10 and a liquid injection port 9 are provided at an intermediate portion in the longitudinal direction of the battery lid 6. The gas discharge valve 10 is provided integrally with the battery cover 6 by thinning the battery cover 6, for example, and cleaves and discharges the gas when the internal pressure of the battery case rises above a predetermined value. The safety of the sealed battery 100 is ensured by reducing the internal pressure of the battery case. The liquid injection port 9 is used to inject an electrolytic solution into the battery case, and after the electrolytic solution is injected, the sealing plug 11 is welded and sealed, for example, by laser welding. As an electrolytic solution to be injected into the battery case, for example, a nonaqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonate organic solvent such as ethylene carbonate is applied. Can do.

  The external terminal 20 has a weld joint that is welded to a bus bar or the like, and connection parts 12 a and 14 a that are connected to the current collector plate 40. The weld joint has a rectangular parallelepiped block shape arranged outside the battery lid 6, the lower surface faces the upper surface of the battery lid 6, and the upper surface is parallel to the upper surface of the battery lid 6 at a predetermined height position. have. The connection parts 12a and 14a protrude in the direction penetrating the battery cover 6 from the lower surface of the welded joint part, and have a cylindrical shape that can be inserted into the circular through holes 26 and 46 of the battery cover 6.

  The current collecting plate 40 is bent at the rectangular plate-like base portions 21 and 41 arranged to face the lower surface of the battery lid 6 and the side edges of the base portions 21 and 41, and extends along the wide side surface 1 b of the battery can 1. It has connection ends 24 and 44 extending in the direction toward the bottom surface. The base portions 21 and 41 of the current collector plate 40 have through holes 23 and 43 through which the connection portions 12 a and 14 a of the external terminal 20 are inserted. The connection end portions 24 and 44 of the current collector plate 40 are superposed so as to face the foil exposed portions 34c and 32c at both ends in the winding axis direction of the wound electrode group 3, for example, ultrasonic welding or resistance welding. Are joined to the foil exposed portions 34c and 32c and electrically connected to the positive electrode 34 and the negative electrode 32 (see FIG. 3) constituting the wound electrode group 3.

  The connecting portions 12a and 14a of the external terminal 20 are the through holes of the gasket 5, the through holes 46 and 26 of the battery cover 6, the through holes of the insulating plate 7, and the through holes 23 and 43 of the base portions 21 and 41 of the current collector plate 40. Are sequentially inserted and crimped so that the tips projecting from the lower surfaces of the base portions 21 and 41 of the current collector plate 40, that is, the surface opposite to the battery lid 6, are expanded. Thereby, the external terminal 20 and the current collector plate 40 are integrally fixed to the battery lid 6 via the gasket 5 and the insulating plate 7, and the wound electrode group 3 is connected to the battery lid 6 via the current collector plate 40 and the insulating plate 7. Fixed to. Further, the external terminal 20 is electrically connected to the positive electrode 34 and the negative electrode 32 (see FIG. 3) constituting the wound electrode group 3 through the current collector plate 40.

  The wound electrode group 3 is covered with the insulating protective film 2 while being fixed to the battery lid 6 via the current collector plate 40 and the insulating plate 7, and is inserted into the battery can 1 from the opening 1 a of the battery can 1. The entire periphery of the battery lid 6 is joined to the entire periphery of the opening 1a of the battery can 1 by, for example, laser welding and enclosed in a battery case. Thereafter, an electrolytic solution is injected into the battery case through the liquid injection port 9 of the battery lid 6, and a sealing plug 11 is joined to the liquid injection port 9 by, for example, laser welding to seal the battery case.

  The manufacturing method of the sealed battery 100 includes a liquid injection process in which an electrolytic solution is injected from the liquid injection port 9 into the battery case, and the liquid injection port 9 is closed with the sealing plug 11 after the liquid injection process. Including a welding step of sealing the liquid injection port 9 by welding to the battery case. In the welding process, an annular boundary portion formed between the battery case and the sealing plug 11 in a state where the liquid injection port 9 is closed with the sealing plug 11 is continuously welded along the boundary portion, The injection port 9 is sealed.

  4 is an enlarged plan view showing a main part of the sealed battery 100, and FIG. 5 is a cross-sectional view taken along the line AA of FIG. In this embodiment, the case where the sealing plug 11 is circular in plan view and there are two welding start points will be described.

  As described above, the battery lid 6 is provided with the liquid injection port 9. The liquid injection port 9 is a through hole for injecting the electrolyte into the battery case, and penetrates the battery lid 6 so as to communicate the inside and outside of the battery case. The liquid injection port 9 is formed in a circular shape in plan view. As shown in FIG. 5, the liquid injection port 9 has a large-diameter hole portion 9 a that opens to the front surface side of the battery lid 6 and a small-diameter hole portion 9 b that opens to the back surface side of the battery lid 6. The diameter hole portion 9a and the small diameter hole portion 9b are continuous through a step.

  The sealing plug 11 is a member for sealing the liquid injection port 9. As shown in FIG. 4, the sealing plug 11 is formed in a circular shape in plan view. The sealing plug 11 is inserted into the circular large-diameter portion 11a inserted into the large-diameter hole portion 9a of the liquid injection port 9 and the small-diameter hole portion 9b of the liquid injection port 9 protruding from the central portion of the large-diameter portion 11a. A convex small-diameter portion 11b. In the example shown in FIG. 5A, the large-diameter portion 11a has substantially the same outer diameter that is the same as or slightly smaller than the diameter of the large-diameter hole portion 9a. In the example shown in FIG. The outer diameter is smaller than the diameter of the diameter hole portion 9a and has a gap between the inner diameter surface of the large diameter hole portion 9a. The small diameter part 11b has substantially the same outer diameter that is the same as or slightly smaller than the diameter of the small diameter hole part 9b. The sealing plug 11 may have any of the configurations shown in FIGS. 5 (a) and 5 (b).

  The sealing plug 11 is welded to the battery lid 6 while being inserted from above the liquid injection port 9 so as to close the liquid injection port 9. The sealing plug 11 has a small diameter portion 11b inserted into the small diameter hole portion 9b and a large diameter portion 11a inserted into the large diameter hole portion 9a, and the upper surface of the large diameter portion 11a is substantially the same as the upper surface of the battery lid 6. Placed in one. And in the case of the example shown to Fig.5 (a), the outer peripheral surface of the large diameter part 11a is arrange | positioned in the state which opposes or contact | abutted the inner peripheral surface of the large diameter hole part 9a. In the example shown in FIG. 5B, the outer peripheral surface of the large-diameter portion 11a is disposed with a gap between the inner peripheral surface of the large-diameter hole portion 9a.

  In the welding process, an annular boundary portion formed between the battery lid 6 and the sealing plug 11 is continuously welded along the boundary portion to seal the liquid injection port 9. In the case of the configuration example shown in FIG. 5A, butt welding for welding a boundary portion between the outer peripheral surface of the large diameter portion 11a of the sealing plug 11 and the inner peripheral surface of the large diameter hole portion 9a of the liquid injection port 9; Become. In the case of the configuration example shown in FIG. 5B, fillet welding is performed to weld a boundary portion between the outer peripheral surface of the large diameter portion 11a of the sealing plug 11 and the bottom surface of the large diameter hole portion 9a of the liquid injection port 9. It becomes.

  Welding is performed by laser welding. Laser welding laser is applied to the boundary portion from above the battery lid 6. In the case of the configuration example shown in FIG. 5A, laser welding can be performed with less energy, and implementation can be performed using a small-scale facility. On the other hand, in the case of the configuration example shown in FIG. 5B, the outer diameter of the large-diameter portion 11a of the sealing plug 11 and the large-diameter hole portion 9a of the liquid injection port 9 are larger than those in the configuration example shown in FIG. Since the dimensional accuracy of the inner diameter can be lowered, the sealing plug 11 and the battery lid 6 can be easily manufactured, and the manufacturing cost can be reduced.

  In the welding process, welding is simultaneously started in the same direction along the boundary portion from a plurality of welding start positions set evenly in the boundary portion. Then, welding is performed from a plurality of welding start positions to other adjacent welding start positions. In the present embodiment, the first welding start position W1S and the second welding start position W2S are set so that the boundary portion that is continuous in an annular shape is equally divided into two. Then, welding is started simultaneously from the first welding start position W1S and the second welding start position W2S in the counterclockwise direction along the boundary portions, respectively, and the adjacent second welding start position W2S and the first welding start position are respectively adjacent. It is welded to W1S. Therefore, the 1st welding part W1 and the 2nd welding part W2 are formed in this boundary part, and a boundary part is sealed. The first welding start position W1S and the second welding start position W2S are set in regions where the weld circumferences of the first welded portion W1 and the second welded portion W2 are equal.

  The welding end position is set to an area that has been welded through another welding start position. In the present embodiment, the welding end position W1E of the first welded portion W1 passes through the second welding start position W2S and is set in the region of the second welded portion W2, and the welding end position W2E of the second welded portion W2 is set. Is set in the region of the first welded portion W1 through the first welding start position W1S. Accordingly, the first weld W1 is formed to partially overlap the second weld W2, and the second weld W2 is formed to partially overlap the first weld W1. Thus, by forming the connection part of the 1st welding part W1 and the 2nd welding part W2 so that it may overlap partially, it receives a reheating effect and the improvement of the leveling of a welding part and toughness is anticipated. .

  In a conventional sealed battery, welding is started from one welding start position. When the lid portion and the sealing plug portion are laser-welded, a cooling shrinkage occurs in the welded region, so that a gap is generated between the lid portion and the sealing plug portion in the unwelded region. The gap is prominent in the unwelded region in the substantially opposite region of the welded region, causing welding defects such as blow-fall and cracks, which may lead to a decrease in hermeticity. In particular, the sealing plug part is lighter and smaller than other members of the sealed battery, and thus is easily affected by stress due to cooling shrinkage after welding, and the position of the sealing part is easily displaced. Had.

  On the other hand, in the sealed battery 100 of the present embodiment, two or more welding start positions of the sealing plug 11 and the battery lid 6 are provided, and the welding start position is the total welding of the battery lid 6 and the sealing plug 11. It is characterized in that each welding circumferential length is arranged in a substantially equal area with respect to the circumferential length, and welding is started simultaneously from each welding start position. Therefore, the stress due to the cooling shrinkage of the welding region is equally applied to the sealing plug 11, and the movement of the sealing plug 11 with respect to the liquid injection port 9 and the lifting of the sealing plug 11 from the liquid injection port 9 are prevented. Can do.

  Therefore, the sealed battery 100 according to the present embodiment does not have a gap between the battery lid 6 and the sealing plug 11 generated in the unwelded region, which has been a problem in the prior art, and suppresses poor welding. It becomes possible. More specifically, since there is no unwelded region in the substantially opposite region of the welded region where the gap was significant in the prior art, it is possible to suppress poor welding. Further, since the welding process is a downstream process in the manufacturing process of the sealed battery, the welding failure in the welding process is a substantially completed product of the sealed battery. Therefore, the sealed battery 100 according to the present embodiment greatly contributes to the improvement of the defective rate of a substantially completed product that has a great influence on the workability.

  Further, in the sealed battery 100, at least a part of each welding end point in the sealing plug 11 may be arranged in another welding start region. In the present embodiment, the welding end position is set to a welded region passing through the other welding start position. Therefore, the already welded part will be further welded, and it will receive the reheating effect, and leveling of the welded part and improvement of toughness are expected.

  In addition, although the present Example demonstrated as an example the case where it welds counterclockwise along a boundary part from the 1st welding start position W1S and the 2nd welding start position W2S, respectively, the direction to weld is the 1st welding start position. It suffices if they are in the same direction from W1S and the second welding start position W2S. For example, welding may be performed clockwise.

FIG. 6 is a diagram for explaining another embodiment and corresponds to FIG.
In the embodiment shown in FIG. 4, the case where the sealing plug 11 is circular in plan view has been described. However, as shown in FIG. 6, the present invention is similarly applied to the case where the sealing plug 11 is elliptical in plan view. be able to.

  In order to secure a larger opening area of the liquid injection port and improve the liquid injection efficiency, it has been conventionally performed that the shape of the liquid injection port is an elliptical shape in plan view. In the case of the embodiment shown in FIG. 6, the liquid injection port (not shown) and the sealing plug 11 are arranged such that the long axis is along the longitudinal direction of the battery lid 6. And the 1st welding start position W1S and the 2nd welding start position W2S are set so that it may be divided and located in the longitudinal direction one side and other side of battery lid 6 on both sides of the diameter direction center position of sealing plug 11 Yes. When the sealing plug 11 is oval, the diameter of the major axis side of the sealing plug 11 is longer than that of the minor axis side. Therefore, when welding is started from the end of one major axis side, the cooling shrinkage of the welding region However, according to the above configuration, the lifting of the sealing plug 11 can be effectively suppressed, and the gap portion of the gap can be reduced. Occurrence can be prevented.

FIG. 7 is a diagram for explaining another embodiment and corresponds to FIG.
In the examples shown in FIGS. 4 and 6, the case where the welding start positions are two has been described, but the present invention can also be applied to the case where there are three or more positions. In the embodiment shown in FIG. 7, there are three welding start positions, and a first welding start position W1S, a second welding start position W2S, and a third welding start position W3S are set. The first welding start position W1S, the second welding start position W2S, and the third welding start position W3S are set so as to be evenly positioned along the boundary portion, and are 120 to each other with the center of the sealing plug 11 as a reference. It is set to a position having an angle of degrees.

  Then, welding is started simultaneously counterclockwise from the first welding start position W1S, the second welding start position W2S, and the third welding start position W3S, respectively along the boundary portions, and the first welding portion W1 and the second welding portion. W2 and the third weld W3 are formed. The first welding start position W1S, the second welding start position W2S, and the third welding start position W3S are areas in which the welding perimeters of the first welding portion W1, the second welding portion W2, and the third welding portion W3 are equal. Is set to

  According to the said structure, since an unwelded area | region can be reduced compared with two cases, there exists an effect which the clearance gap between the said cover part and the said sealing plug part becomes difficult to produce more. That is, by increasing the welding start position, it becomes easy to obtain a suppression of welding failure due to the gap.

[Embodiment 2]
FIG. 8 is a diagram for explaining the second embodiment, FIG. 8 (a) is a diagram for explaining the primary welding process, and FIG. 8 (b) is a diagram for explaining the secondary welding process.
Note that the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  What is characteristic in this embodiment is that simultaneous welding is performed in a plurality of times with a predetermined time interval. The welding process includes a primary welding process and a secondary welding process. In the primary welding process, welding is performed from a plurality of welding start positions to adjacent welding end positions. In the secondary welding process, welding is performed from a welding end position in the primary welding process to another welding start position after a predetermined time has elapsed from the primary welding process.

  In the present embodiment, the first welding start position W1S and the second welding start position W2S are set so that the boundary portion that is continuous in an annular shape is equally divided into two. As shown in FIG. 8A, the first welding start position W1S and the second welding start position W2S are separated to one side and the other side in the longitudinal direction of the battery lid 6 with the radial center position of the sealing plug 11 in between. Is set to the correct position.

  Then, in the primary welding process, welding is simultaneously started counterclockwise along the boundary portions from the first welding start position W1S and the second welding start position W2S, respectively, and the adjacent first welding end position W1E and second welding are respectively set. Welding is performed up to the end position W2E. In this embodiment, the first welding end position W1E and the second welding end position W2E are 90 degrees from the first welding start position W1S and the second welding start position W2S, respectively, with the radial center position of the sealing plug 11 as a reference. It is set at a position separated within an angle range of less than 180 degrees. Therefore, as shown to Fig.8 (a), the 1st welding part W1 and the 2nd welding part W2 are formed in a boundary part. The first welded portion W1 and the second welded portion W2 are formed at positions where the boundary portions are partially joined to each other by an equal length and separated from each other along the boundary portion.

  The predetermined time from the end of the primary welding process to the start of the secondary welding process is a preset time. For example, the temperature of the first welded portion welded by the primary welding process is reduced to a predetermined temperature or lower. The time until is set. In the secondary welding process, welding is simultaneously started counterclockwise along the boundary portion from the third welding start position W3S and the fourth welding start position W4S, respectively, and the adjacent third welding end position W3E and the fourth welding end, respectively. Welding to position W4E.

  The welding start position in the secondary welding process is set in the area of one first welded part in the primary welding process, and the welding end position in the secondary welding process is set in the area of the other first welded part in the primary welding process. Has been. That is, the third welding start position W3S and the fourth welding start position W4S are set in the region of the first welding part W1 and the region of the second welding part W2, respectively. The third welding end position W3E and the fourth welding end position W4E are respectively set in the region of the second welding part W2 and the region of the first welding part W1.

  Therefore, the first welding end position W1E of the first welding part W1 and the second welding start position W2S of the second welding part W2 are connected by the third welding part W3, and the first welding start of the first welding part W1 is started. The fourth welding portion W4 connects between the position W1S and the second welding end position W2E of the second welding portion W2.

  And the 3rd welding part W3 is formed so that the edge part by the side of the 3rd welding start position W3S may partially overlap with the edge part by the side of the 1st welding end position W1E of the 1st welding part W1, and the 3rd welding end The end portion on the position W3E side is formed so as to partially overlap the end portion on the second welding start position W2S side of the second welding portion W2. And the 4th welding part W4 is formed so that the edge part by the side of the 4th welding start position W4S may overlap with the edge part by the side of the 2nd welding end position W2E of the 2nd welding part W2, and the 4th welding end The end on the position W4E side is formed so as to partially overlap the end on the first welding start position W1S side of the first welding part W1. Therefore, a portion where the first welded portion W1 to the fourth welded portion W4 overlap each other is expected to receive a reheating effect, and leveling of the welded portion and improvement of toughness are expected.

  In addition, although the present Example demonstrated as an example the case where a boundary part was welded in 2 steps, a primary welding process and a secondary welding process, you may carry out in 3 steps or more. By dividing the welding process into three or more times, increasing the number of locations where at least a part of the welding end position is distributed to other welds leads to an increase in the area of the reheating effect, and leveling of the welds And toughness can be improved more easily.

  In each of the above-described embodiments, the electrode group wound in a flat shape is illustrated, but the present invention is not limited to this, and an electrode group wound in a columnar shape or an electrode group in which positive and negative electrodes are stacked is used. It may be. In this embodiment, the rectangular battery is exemplified, but the present invention can be applied to a cylindrical battery or a flat battery, and can also be applied to a sealed battery in which an electrolytic solution is an aqueous electrolytic solution. Further, in the present embodiment, the electrode group having the axis is illustrated, but an electrode group without the axis may be used in order to reduce the battery weight. At that time, in order to increase the output volume density of the battery, the electrode group wound in a flat shape with a predetermined pressure may be crushed.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

Since the present invention provides a lightweight sealed battery that can ensure hermeticity and contributes to the manufacture and sale of sealed batteries, it has industrial applicability.

DESCRIPTION OF SYMBOLS 1 Battery can 6 Battery cover 9 Injection port 11 Seal plug 100 Sealed battery W1 1st welding part W2 2nd welding part W3 3rd welding part W4 4th welding part W1S 1st welding start position W2S 2nd welding start position W3S Third welding start position W4S Fourth welding start position W1E First welding end position W2E Second welding end position W3E Third welding end position W4E Fourth welding end position

Claims (6)

A method for producing a sealed battery comprising a battery case having a liquid inlet and a sealing plug for sealing the liquid inlet,
A liquid injection step of injecting an electrolytic solution into the battery case from the liquid injection port;
After the liquid injection step, the liquid injection port is closed with the sealing plug, and an annular boundary portion formed between the battery case and the sealing plug is continuously welded along the boundary portion. And a welding step for sealing the liquid injection port,
In the welding step, welding is simultaneously started in the same direction along the boundary portion from a plurality of welding start positions set equally to the boundary portion, and other welding start positions adjacent to each other from the plurality of welding start positions. And the welding end position is set to a welded region after passing through the other welding start position . A method for producing a sealed battery comprising a battery case having a liquid inlet and a sealing plug for sealing the liquid inlet,
A liquid injection step of injecting an electrolytic solution into the battery case from the liquid injection port;
After the liquid injection step, the liquid injection port is closed with the sealing plug, and an annular boundary portion formed between the battery case and the sealing plug is continuously welded along the boundary portion. And a welding step for sealing the liquid injection port,
In the welding step, welding is simultaneously started in the same direction along the boundary portion from a plurality of welding start positions set equally to the boundary portion, and the welding is divided into a plurality of times with a predetermined time interval. tightly closed method for producing a battery you and performing. The welding process includes
A primary welding step of performing welding from the plurality of welding start positions to adjacent welding end positions;
A secondary welding step of performing welding from the welding end position to another adjacent welding start position after elapse of a predetermined time from the primary welding step;
The method for producing a sealed battery according to claim 2 , comprising: The welding start position in the secondary welding process is set in the region of one first welded part by the primary welding process,
The method for manufacturing a sealed battery according to claim 3 , wherein a welding end position in the secondary welding step is set in a region of the other first welded portion in the primary welding step. The method for manufacturing a sealed battery according to any one of claims 1 to 4 , wherein the boundary portion has a circular shape in a plan view. The said boundary part has a planar view ellipse, The manufacturing method of the sealed battery as described in any one of Claims 1-4 characterized by the above-mentioned.

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