JP2018037333A - Manufacturing method of secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a secondary battery which suppresses damage to a current collector foil joined to a current collector terminal by welding. A secondary battery includes an electrode body (20) made of a laminate of a positive electrode current collector foil, a separator, and a negative electrode current collector foil. The electrode body 20 has an electrode main body 25, and a current collector foil extending portion 24 formed by extending the positive electrode current collector foil and the negative electrode current collector foil on both sides of the electrode main body portion 25 with the electrode main body portion 25 interposed therebetween. .. The secondary battery further includes a collector terminal 41 to which the collector foil extending portion 24 is joined. The secondary battery manufacturing method includes a step of sandwiching a plurality of current collector foils 21 constituting the current collector foil extension 24 with current collector terminals 41 in the stacking direction of the current collector foils 21, an electrode body 25 and a current collector terminal 25. By irradiating the plurality of current collector foils 21 with laser light in a state in which the bent portions 61 are provided in the current collector foil extending portions 24 between the current collector terminals 41, the plurality of current collector foils 21 are removed. Welding the current collecting terminal 41. [Selection diagram] Fig. 9

Description

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

  Regarding a conventional method for manufacturing a secondary battery, for example, in Japanese Patent Laid-Open No. 10-261441 (Patent Document 1), a variation in internal resistance is reduced in a joint between a power generation element and a battery external terminal, and high reliability is achieved. A non-aqueous electrolyte secondary battery has been disclosed for the purpose of manufacturing a junction at low cost.

  In the method for manufacturing a non-aqueous electrolyte secondary battery disclosed in Patent Document 1, the edge of the electrode is inserted into the narrowed portion of the current collector provided with the slit, and the tip of the edge of the electrode is protruded from the slit. . Then, the electrode and the current collector are welded by scanning the laser along the edge of the electrode protruding from the slit.

  In addition, as a document disclosing a conventional method of manufacturing a secondary battery, JP 2011-243575 A (Patent Document 2), JP 10-106536 A (Patent Document 3), and JP 2013-179015 A ( There exists patent document 4).

JP-A-10-261441 JP 2011-243575 A Japanese Patent Laid-Open No. 10-106536 JP 2013-179015 A

  As disclosed in Patent Document 1 described above, a plurality of stacked current collector foils are sandwiched between current collector terminals, and a plurality of the current collector foils sandwiched are joined to the current collector terminals by welding. Manufacturing methods are known.

  In such a secondary battery manufacturing method, a plurality of current collecting foils and current collecting terminals are integrated with each other by melting and then solidifying. However, since the melted portions of the current collector foils and the current collector terminals contract in the course of solidification, the unmelted portion of the current collector foil may be pulled by the melted portion and broken.

  Accordingly, an object of the present invention is to solve the above-described problems and to provide a method for manufacturing a secondary battery that suppresses damage to a current collector foil joined to a current collector terminal by welding.

  In the method for producing a secondary battery according to the present invention, the secondary battery includes an electrode body composed of a laminate of a positive electrode current collector foil, a separator, and a negative electrode current collector foil. The electrode body comprises a positive electrode current collector foil and a negative electrode current collector foil laminated via a separator, and a positive electrode current collector foil and a negative electrode current collector foil sandwiching the electrode main body part, respectively. And a current collector foil extending portion extending on both sides thereof. The secondary battery further includes a current collecting terminal to which the current collecting foil extending portion is joined. A method for manufacturing a secondary battery includes a step of sandwiching a plurality of current collector foils constituting a current collector foil extending portion by current collector terminals in the stacking direction of the current collector foil, and between the electrode main body portion and the current collector terminals. In the state where the current collector foil extension part is provided with a bent portion, the current collector foil is irradiated with energy rays toward the current collector foil sandwiched between the current collector terminals, thereby collecting the current collector foils into the current collector terminal. And a step of welding.

  According to the method of manufacturing a secondary battery configured as described above, when the plurality of current collector foils are welded to the current collector terminals, the plurality of current collector foils and the current collector terminals are melted, Coagulates and shrinks. At this time, since the bent portion is provided in the current collector foil extending portion between the electrode main body portion and the current collector terminal, the tensile stress acting on the current collector foil can be relieved as the melted portion is solidified and contracted. it can. Thereby, damage to the current collector foil joined to the current collector terminal by welding can be suppressed.

  As described above, according to the present invention, it is possible to provide a method for manufacturing a secondary battery that suppresses breakage of a current collector foil joined to a current collector terminal by welding.

It is sectional drawing which shows the secondary battery manufactured by the manufacturing method of the secondary battery in embodiment of this invention. It is a perspective view which shows the electrode body with which the secondary battery in FIG. 1 is provided in the single-piece | unit state (state at the time of an assembly). FIG. 3 is an exploded view showing an electrode body in FIG. 2. FIG. 2 is an exploded view illustrating a connection structure between an external terminal and a current collecting terminal in FIG. 1. It is a perspective view which shows the current collection terminal with which the secondary battery in FIG. 1 is provided in the single-piece | unit state (state at the time of an assembly). It is sectional drawing which shows the 1st process of the manufacturing method of the secondary battery in FIG. It is sectional drawing which shows the 2nd process of the manufacturing method of the secondary battery in FIG. It is sectional drawing which shows the 3rd process of the manufacturing method of the secondary battery in FIG. It is sectional drawing which shows the 4th process of the manufacturing method of the secondary battery in FIG. It is sectional drawing which shows the 5th process of the manufacturing method of the secondary battery in FIG. It is a figure which shows the implementation condition of a tensile strength test. It is a table | surface which shows the result of a tensile strength test, and the result of the cross-sectional observation of a welding part.

(Embodiment)
Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are denoted by the same reference numerals.

  FIG. 1 is a cross-sectional view showing a secondary battery manufactured by the method for manufacturing a secondary battery in the embodiment of the present invention. With reference to FIG. 1, the structure of the secondary battery 10 manufactured using the secondary battery manufacturing method in the present embodiment will be described first.

  The secondary battery 10 is for driving a vehicle. For example, a hybrid vehicle that uses an internal combustion engine such as a gasoline engine or a diesel engine and a motor supplied with power from a chargeable / dischargeable battery as a power source, or external charging is possible. It will be installed in plug-in hybrid vehicles and electric vehicles.

  The secondary battery 10 is a non-aqueous electrolyte secondary battery. The secondary battery 10 is a lithium ion battery.

  The secondary battery 10 includes an electrode body 20, a case body 31, a positive electrode external terminal 36P and a negative electrode external terminal 36N, a positive electrode current collector terminal 41P, and a negative electrode current collector terminal 41N (hereinafter, for positive electrode). If the external terminal 36P and the negative electrode external terminal 36N are not particularly distinguished from each other, they are simply referred to as “external terminals 36”. If the positive electrode current collector terminal 41P and the negative electrode current collector terminal 41N are not particularly distinguished from each other, they are simply referred to as “current collectors”. Electrical terminal 41 ").

  The case body 31 makes the external appearance of the secondary battery 10. The case body 31 is made of a metal such as aluminum. The case body 31 is configured by combining a main body portion 32 and a lid portion 33. The main body 32 has a substantially rectangular parallelepiped housing shape opened in one direction. The lid 33 is provided so as to close the opening of the main body 32. A positive electrode external terminal 36P and a negative electrode external terminal 36N are attached to the lid 33.

  FIG. 2 is a perspective view showing the electrode body included in the secondary battery in FIG. 1 in a single state (as assembled). FIG. 3 is an exploded view showing the electrode body in FIG.

  1 to 3, the electrode body 20 is accommodated in a case body 31 together with an electrolytic solution. The electrode body 20 is composed of a laminate of a positive electrode current collector foil 21P, a separator 29, and a negative electrode current collector foil 21N (hereinafter, the positive electrode current collector foil 21P and the negative electrode current collector foil 21N in particular). If they are not distinguished, they are simply referred to as “current collector foil 21”).

  More specifically, the positive electrode current collector foil 21P is formed of an aluminum foil having a substantially rectangular shape. A paste 26 containing a positive electrode active material is applied to both surfaces of the positive electrode current collector foil 21P. On one peripheral edge extending in the longitudinal direction of the positive electrode current collector foil 21P, a peripheral edge portion 22 to which the paste 26 is not applied is formed to extend in a band shape.

  The negative electrode current collector foil 21N is formed of a copper foil having the same shape as the positive electrode current collector foil 21P. A paste 27 containing a negative electrode active material is applied to both surfaces of the negative electrode current collector foil 21N. On one peripheral edge extending in the longitudinal direction of the negative electrode current collector foil 21N, a peripheral edge portion 23 to which the paste 27 is not applied is formed extending in a band shape.

  The separator 29 has a substantially rectangular shape in which the length in the short direction is smaller than the positive electrode current collector foil 21P and the negative electrode current collector foil 21N. As the separator 29, for example, a porous polypropylene resin sheet can be used.

  The positive electrode current collector foil 21P, the negative electrode current collector foil 21N, and the two separators 29 are stacked in this order: the positive electrode current collector foil 21P, the separator 29, the negative electrode current collector foil 21N, and the separator 29. At this time, the region where the paste 26 is applied to the positive electrode current collector foil 21P and the region where the paste 27 is applied to the negative electrode current collector foil 21N face each other via the separator 29. The peripheral edge portion 22 of the positive electrode current collector foil 21P is exposed from one end side extending in the longitudinal direction of the separator 29, and the peripheral edge portion 23 of the negative electrode current collector foil 21N is exposed to the other end side extending in the longitudinal direction of the separator 29. Exposed from.

  The electrode body 20 is a wound type, and a laminated body composed of a positive electrode current collector foil 21P, a negative electrode current collector foil 21N, and two separators 29 is centered on a virtual central axis 101 shown in FIG. It is wound. The laminate is wound so that a cross-sectional shape when cut along a plane orthogonal to the central axis 101 is a track shape (a shape in which a rectangle and two semicircles are combined).

  The electrode body 20 includes, as its constituent parts, an electrode main body 25, a positive electrode collector foil extension 24P, and a negative electrode collector foil extension 24N (hereinafter, positive electrode collector foil extension 24P). And the negative electrode current collector foil extension 24N are simply referred to as “current collector foil extension 24”).

  The electrode main body 25 is a portion where the positive electrode current collector foil 21 </ b> P and the negative electrode current collector foil 21 </ b> N are laminated via the separator 29. The positive electrode current collector foil extending portion 24P is a portion where the positive electrode current collector foil 21P extends to one side across the electrode main body 25, and the negative electrode current collector foil extending portion 24N is used for the negative electrode. The current collecting foil 21N is a portion extending to the other side with the electrode main body 25 interposed therebetween. In the axial direction of the central axis 101, the electrode main body 25 is located between the positive electrode current collector foil extension 24P and the negative electrode current collector foil extension 24N.

  In the positive electrode current collector foil extending portion 24P, a plurality of positive electrode current collector foils 21P are laminated in one direction (the thickness direction of the flat electrode body 20). In the negative electrode current collector foil extending portion 24N, a plurality of negative electrode current collector foils 21N are laminated in one direction (the thickness direction of the electrode body 20 having a flat shape).

  The positive electrode current collector terminal 41P electrically connects the positive electrode external terminal 36P and the positive electrode current collector foil extending portion 24P (a plurality of positive electrode current collector foils 21P). The negative electrode current collector terminal 41N electrically connects the negative electrode external terminal 36N and the negative electrode current collector foil extending portion 24N (a plurality of negative electrode current collector foils 21N).

  The current collecting terminal 41 is made of a conductive metal. The positive electrode current collector terminal 41P is formed of the same type of metal as the metal forming the positive electrode current collector foil 21P. The negative electrode current collector terminal 41N is made of the same type of metal as the metal forming the negative electrode current collector foil 21N. The positive electrode current collecting terminal 41P is made of aluminum which does not corrode even at a high potential and has a small specific resistance. The negative electrode current collecting terminal 41N is made of copper having a small specific resistance and not alloying with lithium (Li).

  FIG. 4 is an exploded view showing a connection structure between the external terminal and the current collecting terminal in FIG. FIG. 5 is a perspective view showing a current collecting terminal provided in the secondary battery in FIG. 1 in a single state (state when assembled).

  With reference to FIGS. 1 to 5, the external terminal 36 is superimposed on the lid portion 33 via an insulator 37 from the outside of the case body 31. The current collecting terminal 41 is overlapped with the lid portion 33 via the insulator 38 from the inside of the case body 31. Since the conductive pin member 39 is inserted from the current collecting terminal 41 to the external terminal 36, the current collecting terminal 41 and the external terminal 36 are electrically connected.

  The connection structure between the positive electrode external terminal 36P and the positive electrode current collector terminal 41P is the same as the connection structure between the negative electrode external terminal 36N and the negative electrode current collector terminal 41N.

  The current collecting terminal 41 has a base part 42 and an arm part 43 as its constituent parts. The base portion 42 has a plate shape and is superimposed on the lid portion 33. The arm portion 43 is bent from the base portion 42 and extends in an arm shape in a direction away from the base portion 42. In the arm portion 43, a slit 44m and a slit 44n are formed. The slits 44 m and 44 n extend in a slit shape along the direction in which the arm portion 43 extends in an arm shape, and reach the tip of the arm portion 43. The slits 44m and 44n are arranged at intervals in the thickness direction of the electrode body 20.

  In the present embodiment, a case where a plurality of slits are formed in the arm portion 43 will be described. However, the present invention is not limited to this, and one slit may be formed in the arm portion 43.

  The plurality of positive electrode current collector foils 21P constituting the positive electrode current collector foil extending portion 24P are inserted into the slits 44m and 44n of the positive electrode current collector terminal 41P, and the arm of the positive electrode current collector terminal 41P is inserted. It is joined to the portion 43 by welding. The plurality of negative electrode current collector foils 21N constituting the negative electrode current collector foil extending portion 24N are arranged in the slits 44m and 44n of the negative electrode current collector terminal 41N, and the arm of the negative electrode current collector terminal 41N is disposed. It is joined to the portion 43 by welding.

  The connection structure between the positive electrode current collector terminal 41P and the positive electrode current collector foil 21P and the connection structure between the negative electrode current collector terminal 41N and the negative electrode current collector foil 21N are the same.

  Then, the manufacturing method of the secondary battery in embodiment of this invention is demonstrated. 6 to 10 are cross-sectional views showing the steps of the method for manufacturing the secondary battery in FIG.

  Referring to FIG. 2, first, electrode body 20 is manufactured by winding a laminate including positive electrode current collector foil 21 </ b> P, negative electrode current collector foil 21 </ b> N, and two separators 29.

  With reference to FIGS. 6 to 8, next, the mold device 50 is used to form the tip end portion 62 and the intermediate portion 63 on the plurality of current collector foils 21 constituting the current collector foil extending portion 24. The bending part 61 is provided.

  Referring to FIG. 8, tip portion 62 is provided at the tip of current collector foil extending portion 24 that extends from electrode main body portion 25. In the front end portion 62, a plurality of current collecting foils 21 constituting the current collecting foil extending portion 24 are bundled. The tip 62 has a substantially constant thickness. The intermediate part 63 is provided between the electrode main body part 25 and the tip part 62. In the intermediate portion 63, the plurality of current collector foils 21 extend from the electrode main body portion 25 toward the distal end portion 62 while approaching each other. The intermediate portion 63 has a thickness that gradually decreases from the electrode main body portion 25 toward the distal end portion 62.

  The bending portion 61 is provided at the distal end portion 62. The bending portion 61 has an extension direction of the current collector foil extension 24 from the electrode body 25 at the front end portion 62 (a direction indicated by an arrow 103, hereinafter, simply referred to as “extension direction of the current collector foil extension 24”). It is bent so as to deviate from. The bending portion 61 is bent in a U shape at the distal end portion 62. The bending portion 61 is a stacking direction of a plurality of current collector foils 21 constituting the current collector foil extending portion 24 (a direction indicated by an arrow 102, hereinafter, also simply referred to as “a stacking direction of a plurality of current collector foils 21”). ) To have a bent shape.

  In the present embodiment, in correspondence with the configuration in which the current collecting terminal 41 is formed with two slits 44m and slits 44n, the current collector foil extending portion 24 has two sets of a tip portion 62 and an intermediate portion 63. And the bending part 61 is provided. When one slit is formed in the current collecting terminal 41, the current collector foil extending portion 24 is provided with a pair of a tip portion 62, an intermediate portion 63, and a bent portion 61.

  Referring to FIG. 6, the mold apparatus 50 includes a first mold 51 and a pair of second molds 56 and 56 ′. Next, the 1st metal mold | die 51 is arrange | positioned so that the current collector foil extension part 24 may be opposed in the extending | stretching direction of the current collector foil extension part 24. FIG. A pair of second molds 56, 56 ′ are arranged on both sides of the current collector foil extension 24 in the stacking direction of the current collector foils 21.

  The 1st metal mold | die 51 has inclination part 52,52 'and recessed part 53,53'. The inclined portions 52 and 52 ′ are provided at positions facing the current collector foil extending portion 24. The inclined portions 52, 52 ′ are configured by inclined surfaces extending obliquely with respect to the extending direction of the current collector foil extending portion 24 and the stacking direction of the plurality of current collector foils 21. The inclined portion 52 and the inclined portion 52 ′ are arranged in the extending direction of the current collector foil extending portion 24 toward the center from both ends of the current collector foil extending portion 24 in the stacking direction of the plurality of current collector foils 21. It approaches the extension part 24 and forms the top at the center of the current collector foil extension part 24 in the stacking direction of the current collector foils 21. The recesses 53, 53 ′ have a recessed shape that is recessed in a direction approaching each other in the stacking direction of the plurality of current collector foils 21.

  The second mold 56 has an inclined portion 58 and a convex portion 57. The second mold 56 'has an inclined portion 58' and a convex portion 57 '. The inclined portion 58 is composed of an inclined surface that forms a pair with the inclined portion 52 in the stacking direction of the current collector foils 21. The inclined portion 58 ′ is composed of an inclined surface that makes a pair with the inclined portion 52 ′ in the stacking direction of the plurality of current collector foils 21. The convex portions 57 and 57 ′ have a convex shape that protrudes in a direction approaching each other in the stacking direction of the plurality of current collector foils 21.

  Referring to FIG. 7, next, the first mold 51 is moved close to the current collector foil extending portion 24 and disposed between the second mold 56 and the second mold 56 ′.

  At this time, the plurality of current collecting foils 21 constituting the current collecting foil extending portion 24 are distributed to the left and right by being deformed along the inclined portion 52 and the inclined portion 52 ′. One of the plurality of current collector foils 21 distributed to the left and right is positioned between the second mold 56 and the first mold 51, and the other of the plurality of current collector foils 21 distributed to the left and right is the first It is positioned between the first mold 51 and the second mold 56 '.

  Next, the second mold 56 and the second mold 56 ′ are moved close to each other in the stacking direction of the plurality of current collector foils 21.

  At this time, the second mold 56 approaches toward the first mold 51, and the second mold 56 ′ approaches toward the first mold 51. And the convex part 57 fits into the recessed part 53 between the 2nd metal mold | die 56 and the 1st metal mold | die 51, and convex part 57 'fits into the recessed part 53' between the 1st metal mold | die 51 and the 2nd metal mold | die 56 '. Match. Thereby, the bending part 61 is provided in the front-end | tip part 62, forming the front-end | tip part 62 in the current collection foil extension part 24. FIG. In addition, the inclined portion 58 approaches the inclined portion 52 between the second mold 56 and the first mold 51, and the inclined portion 58 ′ is inclined between the first mold 51 and the second mold 56 ′. Approach towards ´. Thereby, the intermediate part 63 is formed in the current collector foil extending part 24.

  Referring to FIGS. 9 and 10, next, the two tip portions 62 are inserted into the slit 44m and the slit 44n, respectively. At this time, the bending portion 61 is disposed between the current collecting terminal 41 and the electrode main body portion 25. The bending portion 61 forms a redundant portion where the length of the plurality of current collecting foils 21 is left between the current collecting terminal 41 and the electrode main body portion 25.

  Next, laser light is irradiated toward the front end portion 62 protruding from the current collecting terminal 41, and a direction orthogonal to the paper surface shown in FIG. 9 (perpendicular to the extending direction of the current collector foil extending portion 24) The plurality of current collecting foils 21 are welded to the current collecting terminals 41 by scanning laser light in a direction perpendicular to the stacking direction of the electric foils 21. When the melted portions of the plurality of current collecting foils 21 and the current collecting terminals 41 are solidified, a welded portion 48 shown in FIG. 10 is formed.

  The positive electrode current collector terminal 41 </ b> P and the negative electrode current collector terminal 41 </ b> N are connected to the electrode body 20 by the above-described welding process of the electrode body 20 and the current collector terminal 41. The pin member 39, the insulator 38, the lid 33, the insulator 37, and the external terminal 36 shown in FIG. 4 are assembled to the current collecting terminal 41 integrated with the electrode body 20. As shown in FIG. 1, the electrode body 20 integrated with the external terminal 36 and the lid portion 33 is accommodated in the main body portion 32 of the case body 31, and the lid portion 33 is welded to the main body portion 32. An electrolytic solution is injected into the case body 31 through a liquid injection hole provided in the lid portion 33, and then the liquid injection hole is closed. Through the above steps, the secondary battery 10 in FIG. 1 is completed.

  In the welding process of the electrode body 20 and the current collecting terminal 41, the plurality of current collecting foils 21 and the current collecting terminals 41 are integrated with each other by melting and then solidifying. However, since the melted portions of the current collector foils 21 and the current collector terminals 41 contract in the course of solidification, the unmelted portions of the current collector foils 21 may be pulled by the melted portions and broken. In general, as a connection structure of the electrode body and the current collecting terminal, a plurality of current collecting foils described in the present embodiment are sandwiched between current collecting terminals to perform a welding process, and a plurality of current collecting terminals are connected. Some of them are pressed against current collecting terminals to perform a welding process. When a welding process is performed with a plurality of current collector foils sandwiched between current collector terminals, the volume of the melted portion increases, so that there is a high possibility that the current collector foil will be broken.

  On the other hand, in the manufacturing method of the secondary battery in the present embodiment, the bent portion 61 is provided in the current collector foil extending portion 24 between the electrode main body portion 25 and the current collector terminal 41, so that the melting portion The tensile stress acting on the current collector foil 21 along with the solidification shrinkage can be alleviated. Thereby, it can suppress that the current collection foil 21 cuts off at the time of the process of welding the several current collection foil 21 to the current collection terminal 41. FIG.

  The manufacturing method of the secondary battery according to the embodiment of the present invention described above will be described collectively. In the manufacturing method of the secondary battery according to the present embodiment, the secondary battery 10 includes a positive electrode current collector foil 21P, An electrode body 20 comprising a laminate of the separator 29 and the negative electrode current collector foil 24N is provided. The electrode body 20 includes a positive electrode current collector foil 21P and a negative electrode current collector foil 21N laminated with a separator 29 interposed therebetween, and a positive electrode current collector foil 21P and a negative electrode current collector foil 21N. Each has a current collector foil extending portion 24 extending on both sides of the electrode main body portion 25. The secondary battery 10 further includes a current collecting terminal 41 to which the current collecting foil extending portion 24 is joined. The manufacturing method of the secondary battery includes a step of sandwiching a plurality of current collector foils 21 constituting the current collector foil extending portion 24 by current collector terminals 41 in the stacking direction of the current collector foil 21, and the electrode main body portion 25 and the current collector. In the state where the bent portion 61 is provided in the current collector foil extending portion 24 between the current terminals 41, laser light as an energy beam is irradiated toward the plurality of current collector foils 21 sandwiched by the current collector terminals 41. And a step of welding a plurality of current collecting foils 21 to the current collecting terminals 41.

  According to the secondary battery manufacturing method in the embodiment of the present invention configured as described above, it is possible to suppress damage to the current collector foil 21 joined to the current collector terminal 41 by welding. Thereby, the raise of the internal resistance of a secondary battery and deterioration of battery performance can be prevented.

  In the present embodiment, the current collector foil extending portion 24 is provided with the bent portion 61 having a bent shape that is convex toward the stacking direction of the plurality of current collector foils 21, but the same bent shape is provided. A plurality of the bent portions 61 may be provided. In this case, the tensile stress acting on the current collector foil 21 along with the solidification and shrinkage of the melted portions of the current collector foils 21 and the current collector terminals 41 can be more effectively reduced.

  In the present embodiment, the wound type electrode body 20 has been described. However, the present invention is not limited to this, and the electrode body is a laminated type in which a positive electrode current collector foil and a negative electrode current collector foil are repeatedly laminated via a separator. It may be. Further, an electron beam may be used in place of the laser beam during the welding process of the electrode body 20 and the current collecting terminal 41.

(Example)
Twelve secondary batteries in the examples were manufactured according to the steps of the method for manufacturing a secondary battery in the above embodiment. Moreover, twelve secondary batteries in the comparative example were manufactured by carrying out the welding process without providing the bent portion 61 in the current collector foil extending portion 24.

  At this time, an aluminum foil (or aluminum alloy foil) having a thickness of 15 μm was used as the current collector foil 21P for the positive electrode, and an electrolytic copper foil having a thickness of 10 μm was used as the current collector foil 21N for the negative electrode. A positive electrode active material mixture layer and a negative electrode active material mixture layer were formed on the surfaces of the positive electrode current collector foil 21P and the negative electrode current collector foil 21N, respectively.

  The positive electrode current collector foil 21P and the negative electrode current collector foil 21N were cut into predetermined sizes. A positive electrode current collector foil 21P and a negative electrode current collector foil 21N are laminated via a porous insulating layer as a separator 29, and the obtained laminate is wound to produce the electrode body 20 in FIG. did.

  A current collecting terminal 41 for the positive electrode was produced using an aluminum plate having a thickness of 1.0 mm, and a current collecting terminal 41 for a negative electrode was produced using a copper plate having a thickness of 1.0 mm.

  As welding conditions for the positive electrode during the welding process, a fiber laser was used, the output was 2000 W, and the scanning speed was 20 mm / sec. As welding conditions for the negative electrode during the welding process, a fiber laser was used, the output was 3000 W, and the scanning speed was 30 mm / sec.

  FIG. 11 is a diagram showing an implementation status of the tensile strength test. FIG. 12 is a table showing the results of the tensile strength test and the results of cross-sectional observation of the welded portion.

  Referring to FIG. 11 and FIG. 12, the secondary batteries in the five examples and the secondary batteries in the five comparative examples among the manufactured twelve examples and the twelve comparative examples. The tensile strength test of the current collection terminal 41 with respect to the electrode body 20 was implemented.

  In the tensile strength test, a tensile tester (manufactured by Imada Manufacturing Co., Ltd., model: SV-301) was used. As shown in FIG. 11, the electrode body 20 with terminals welded to a tensile tester was set, and the peak tensile strength in the shear direction was measured at a tensile speed of 0.1 mm / s.

  Using a vibration tester, a vibration test of the secondary battery was performed at 3.5 GHz and up and down vibrations of 2 million times. The secondary battery after the vibration test was subjected to the same tensile strength test as described above. In FIG. 12, the average value of the tensile strength in the secondary battery before the vibration test and the average value of the tensile strength in the secondary battery after the vibration test are shown.

  Furthermore, a part (welded portion) of the electrode body 20 was resin-enclosed using a secondary battery before and after the vibration test in which the tensile strength test was not performed. After the resin was cured, the weld was cut in the cross-sectional direction, and the cut surface was observed with a microscope. FIG. 12 shows the observation result of the cut surface.

  In the secondary batteries in Examples, there was almost no difference between the tensile strength of the secondary battery before the vibration test and the tensile strength of the secondary battery after the vibration test, and good tensile strength could be obtained. On the other hand, in the secondary battery in the comparative example, the tensile strength was lower before the vibration test and after the vibration test as compared with the secondary battery in the example, and the decrease in the tensile strength due to the vibration test was also remarkable.

  Further, in the cross-sectional observation of the welded portion, the current collector foil 21 was not broken in the secondary battery in the example, but the current collector foil 21 was broken in the secondary battery in the comparative example. .

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention is applied to, for example, a method for manufacturing an in-vehicle secondary battery.

  DESCRIPTION OF SYMBOLS 10 Secondary battery, 20 Electrode body, 21 Current collecting foil, 21N Current collecting foil for negative electrode, 21P Current collecting foil for positive electrode, 22, 23 Peripheral part, 24 Current collecting foil extension part, 24N Current collecting foil extension for negative electrode Part, 24P positive electrode current collector foil extension part, 25 electrode body part, 26, 27 paste, 29 separator, 31 case body, 32 body part, 33 lid part, 36 external terminal, 36N negative electrode external terminal, 36P for positive electrode External terminal, 37, 38 insulator, 39 pin member, 41 current collecting terminal, 41N current collecting terminal for negative electrode, 41P current collecting terminal for positive electrode, 42 base part, 43 arm part, 44m, 44n slit, 48 welded part, 50 gold Mold device, 51 First mold, 52, 52 ′, 58, 58 ′ inclined part, 53, 53 ′ concave part, 56, 56 ′ Second mold, 57, 57 ′ convex part, 61 flexure part, 62 tip part 63, middle part, 10 1 Central axis.

Claims (1)

A method for manufacturing a secondary battery, comprising:
The secondary battery is
An electrode body comprising a laminate of a positive electrode current collector foil, a separator and a negative electrode current collector foil,
The electrode body includes an electrode body portion in which the positive electrode current collector foil and the negative electrode current collector foil are laminated via the separator, and the positive electrode current collector foil and the negative electrode current collector foil, A current collector foil extending part extending on both sides of the electrode body part, and further,
Comprising a current collecting terminal to which the current collecting foil extending portion is joined;
The manufacturing method of the secondary battery is as follows:
Sandwiching a plurality of current collector foils constituting the current collector foil extending portion by the current collector terminals in the stacking direction of the current collector foils; and
An energy ray is directed toward the plurality of current collector foils sandwiched between the current collector terminals in a state in which a bent portion is provided in the current collector foil extension between the electrode body portion and the current collector terminal. And a step of welding a plurality of the current collector foils to the current collector terminal by irradiation.

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