JP2017091721A - Method for manufacturing secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a secondary battery, which can suppress the spouting of an electrolytic solution to the outside in degasification of exhausting gas produced in a battery case, thereby reducing the deposition of an electrolytic solution on a welded portion in a welding step after that.SOLUTION: A method for manufacturing a secondary battery comprises the steps of: exhausting gas by opening a pressure relief valve 31; and clogging a liquid inlet by welding a metal plate 20 of the pressure relief valve 31 to a lid. The pressure relief valve 31 includes: the metal plate 20 disposed on an outer surface side of the lid part; an insertion part connected to the metal plate 20 and inserted in a hole part 15; and an annular elastic member provided between the metal plate 20 and the lid and surrounding an opening of the hole part 15. At least a part of the elastic member is formed by an elastically deformable porous member 24; and a member for the clogging is formed by welding the metal plate 20.SELECTED DRAWING: Figure 5

Description

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

  Secondary batteries such as lithium ion secondary batteries are mounted on devices such as personal computers and electric vehicles (Patent Documents 1 and 2 below).

  Japanese Unexamined Patent Application Publication No. 2014-93230 describes a method for manufacturing a secondary battery. A method for manufacturing a secondary battery described in Japanese Patent Application Laid-Open No. 2014-93230 includes a step of housing an electrode body in a case body, and a step of forming a battery case by welding a case lid to an opening of the case body. And a step of injecting an electrolytic solution into the battery case from a liquid injection hole formed in the case lid.

  The method for manufacturing the secondary battery includes a step of forming a sealing member in the injection hole after injecting the electrolytic solution to temporarily seal the injection hole, an initial charging step of performing initial charging after temporary sealing, A degassing step of operating the stop member to connect the inside and outside of the battery case to release the gas in the battery case, and a main seal that seals the liquid injection hole by welding the sealing member to the lid after the degassing step Process.

  The sealing member includes a metal lid portion disposed on the upper surface of the battery case, and an insertion portion formed on the lower surface of the lid portion and inserted into the liquid injection hole. The insertion portion includes a cylindrical shaft portion, a tip portion formed at the lower end portion of the shaft portion, and a plurality of protrusion portions formed near the upper end portion of the shaft portion and disposed on the upper surface of the battery case. . The tip portion is inserted into the battery case, and when the tip portion is attracted upward, the tip portion closes the liquid injection hole.

  In a state where no load is applied to the lid portion of the sealing member, the distal end portion of the insertion portion is in close contact with the lid portion due to the elastic force of the protruding portion, and the liquid injection hole is closed. When the lid portion of the sealing member is pressed, the projecting portion is deformed and the tip portion is separated from the liquid injection hole. Thus, an exhaust passage is formed in which the liquid injection hole communicates with the inside of the battery case and the outside. In this way, the gas generated during the initial charge is exhausted to the outside.

  In the main sealing step, the lid portion of the sealing member is pressed and the lid portion is welded to the upper surface of the battery case in a state where the exhaust passage is formed. At this time, the entire circumference of the outer peripheral edge of the metal part is welded, and the battery case is sealed.

JP 2011-86604 A JP 2013-25882 A JP 2014-93230 A

  In the above secondary battery manufacturing method, when degassing, the electrolyte in the battery case may blow out to the outside of the battery case through the exhaust passage.

  As a result, the electrolytic solution may adhere to the welded portion. In the welding process after degassing, if welding is performed in a state where the electrolytic solution adheres to the welded portion, the attached electrolytic solution may evaporate, which may lead to poor welding.

  The present invention has been made in view of the problems as described above, and its purpose is to suppress the electrolyte from being sprayed to the outside during degassing, so that the electrolyte is attached to the portion to be welded. It is to provide a method for manufacturing a secondary battery that can form a good weld in a welding process of welding and sealing a liquid injection hole.

  In one aspect, a method for manufacturing a secondary battery according to the present invention includes a battery case including a lid portion in which a hole portion is formed, an electrode body and an electrolyte solution disposed in the battery case, and a hole portion. A method of manufacturing a secondary battery including a closing member that is closed. Welding the lid with the hole opened to the case body to form a battery case, placing the electrode body in the battery case, and injecting an electrolyte into the battery case from the hole; Forming a pressure relief valve in the hole, charging the electrode body after forming the pressure relief valve, opening the pressure relief valve so that the inside of the battery case and the outside of the battery case communicate, and pressure relief Welding a portion of the valve to the lid to form a closure member.

  The pressure release valve is provided between the metal plate disposed on the outer surface side of the lid portion, the insertion portion connected to the metal plate and inserted into the hole portion, and the metal plate and the lid. And an annular elastic member surrounding the opening of the hole.

  At least a part of the elastic member is formed of a porous member that can be elastically deformed. The insertion portion includes a shaft portion inserted into the elastic member and the hole portion, and a tip portion formed at an end portion of the shaft portion. In a state where no external force is applied to the metal plate, the tip end part is in close contact with the inner surface of the lid by the elastic force of the elastic member to close the hole.

  By pressing the metal plate toward the lid, the tip portion is separated from the inner surface, and a ventilation passage is formed that passes through the hole and the porous member and communicates the battery case with the outside. The step of opening the pressure release valve includes a step of pressing the metal plate to form a ventilation passage. The step of forming the closing member includes a step of welding the entire circumference of the outer peripheral edge of the metal plate to the lid.

  In the above secondary battery manufacturing method, when the vent passage is formed in the step of opening the pressure release valve, the gas in the battery case is exhausted to the outside through the porous member. When the gas passes through the porous chamber member, the electrolyte contained in the gas is removed. For this reason, it is suppressed that the electrolyte solution in a battery case spouts outside. Thereby, when welding the metal plate to the lid, it is possible to suppress the electrolyte from adhering to the welded portion, the entire circumference of the outer peripheral edge of the metal plate can be favorably welded to the lid portion, The battery case can be sealed.

  According to the method for manufacturing a secondary battery according to the present invention, it is possible to suppress the electrolytic solution or the like from being blown out of the battery case in the degassing step, and during the welding step of closing the hole for injecting the electrolytic solution. And it can suppress that electrolyte solution adheres to a welding part.

1 is a perspective view showing a secondary battery 1. It is sectional drawing which shows the structure of the closure member 16 and its periphery. 4 is a manufacturing flow showing a part of the manufacturing process of the battery case 2. It is sectional drawing which shows the 1st process of process S4. It is sectional drawing which shows the 2nd process of process S4. It is sectional drawing which shows the mode of process S7. It is sectional drawing which shows process S8 of FIG. 6 is a side view showing a first modification of the internal pressure release valve 31. FIG. It is a top view when the internal pressure release valve 31 is seen from the direction of the arrow shown in FIG. It is a side view which shows the 2nd modification of an internal pressure release valve. It is a top view when it planarly views from the direction of the arrow shown in FIG. It is a table | surface which shows the result compared about the airtightness about the secondary battery which concerns on a comparative example, and the secondary battery which concerns on Examples 1-3. It is a perspective view which shows internal pressure release valve 31D used in the manufacture process of the secondary battery of a comparative example. It is sectional drawing which shows process S4 of the manufacturing process of the secondary battery of a comparative example. It is sectional drawing which shows process S7 of the manufacturing process of the secondary battery of a comparative example. It is sectional drawing which shows process S8 of the manufacturing process of the secondary battery of a comparative example.

  FIG. 1 is a perspective view showing a secondary battery 1. As shown in FIG. 1, the secondary battery 1 includes a battery case 2, and an electrode body 3 and an electrolytic solution 4 disposed in the battery case 2.

  The battery case 2 includes a case main body 5, a lid 6 welded to the case main body 5, and a welded portion 7 that welds the case main body 5 and the lid 6.

  The lid 6 includes an outer surface 10 located outside the battery case 2 and an inner surface 11 located within the battery case 2. The lid 6 is formed with an explosion-proof valve 18 that is thinner than the other portions. A terminal 12 and a terminal 13 are provided on the outer surface 10 of the lid 6 so as to be spaced apart from each other. A hole 15 reaching the inner surface 11 from the outer surface 10 is formed in the lid 6, and a closing member 16 for closing the hole 15 is provided in the hole 15.

  FIG. 2 is a cross-sectional view showing the configuration of the closing member 16 and its surroundings. As shown in FIG. 2, a recess 17 is formed on the outer surface 10 of the lid 6, and the hole 15 is formed so as to communicate with the recess 17.

  The closing member 16 includes a metal plate 20 including an outer surface 26 and an inner surface 27, a porous member 24, an insertion portion 21, and a weld portion 28 formed on the outer peripheral edge portion of the metal plate 20.

  The metal plate 20 is formed so as to close the opening of the recess 17, and the metal plate 20 is welded to the opening edge of the recess 17 by a welding portion 28.

  The metal material that forms the metal plate 20 and the metal material that forms the lid 6 are preferably formed of the same metal material. The metal plate 20 is made of aluminum such as A1050 and A3003, for example.

  The porous member 24 is formed in an annular shape so as to surround the periphery of the opening edge 25 of the hole 15 located on the outer surface 10 side. A plurality of fine ventilation paths are formed in the porous member 24, and the porous member 24 has air permeability. The Gurley value (time required for 100 ml of gas to permeate) of the porous member 24 is 50 (seconds) or less, and preferably 10 (seconds) or less.

  The porous member 24 is formed of an elastically deformable material, and the porous member 24 is at least selected from the group consisting of PTFE (polytetrafluoroethylene), PP (polypropylene), and PE (polyethylene), for example. One resin is formed. The Young's modulus of the porous member 24 is 10 to 100 MPa.

  The insertion portion 21 has one end connected to the inner surface 27 of the metal plate 20, a shaft portion 22 disposed in the porous member 24 and the hole portion 15, and a tip portion connected to the other end of the shaft portion 22. 23.

  The diameter of the root portion of the tip portion 23 is larger than the diameter of the opening edge portion 25 and the diameter of the shaft portion 22, and the tip portion 23 is formed so as to taper away from the shaft portion 22.

  Since the diameter of the root portion of the tip portion 23 is larger than the diameter of the shaft portion 22, an end face 30 that surrounds the periphery of the shaft portion 22 in an annular shape is formed on the tip portion 23. As shown in FIG. 2, the end surface 30 is separated from the inner surface 11 of the lid 6.

  The insertion portion 21 is formed so as to be elastically deformable, and the insertion portion 21 is made of, for example, EPDM (ethylene-propylene rubber) or butyl rubber. The elastic coefficient (spring constant) of the insertion portion 21 is not less than the elastic coefficient (spring constant) of the porous member 24.

  The welded portion 28 connects the opening edge portion of the recess 17 and the outer peripheral edge portion of the metal plate 20, and is formed over the entire periphery of the outer peripheral edge portion of the metal plate 20. Thus, since the welding part 28 is formed over the perimeter of the metal plate 20, the battery case 2 is sealed.

  A method for manufacturing the secondary battery 1 configured as described above will be described. FIG. 3 is a manufacturing flow showing a part of the manufacturing process of the battery case 2.

  As shown in FIG. 3, the manufacturing process for manufacturing the secondary battery 1 includes a process S <b> 1 for placing the electrode body 3 in the case body 5, a process S <b> 2 for welding the lid 6 to the case body 5, and the hole 15. Step S3 of injecting the electrolyte solution 4 from Furthermore, the manufacturing method of the secondary battery 1 includes the step S4 of forming the pressure release valve in the hole 15 after injecting the electrolytic solution 4, and charging the electrode body 3 in a state where the hole 15 is sealed with the pressure release valve. (Initial charging) Step S5 and Step S6 of leaving the secondary battery 1 for a predetermined period after initial charging for aging.

  Further, in the manufacturing process of the secondary battery 1, in order to exhaust the gas in the battery case 2 to the outside, a step S 7 for opening the pressure release valve, and a part of the pressure release valve is welded to the lid 6 to close the closing member. 16 and the process S8 which closes the hole 15 at the same time.

  In FIG. 1, in step S <b> 1, the electrode body 3 is accommodated in the case body 5 in a state where the terminals 12 and 13 of the lid 6 and the electrode body 3 are connected. At this time, the lid 6 is disposed in the opening of the case body 5.

  In step S2, the battery case 2 is formed by irradiating the outer peripheral edge of the lid 6 and the opening edge of the case body 5 with laser light and welding the lid 6 and the case body 5. At this time, a hole 15 is formed in the lid 6 and the hole 15 is open. In step S3, a nozzle is inserted into the hole 15 and an electrolytic solution is injected from the nozzle.

  FIG. 4 is a cross-sectional view showing a first step of step S4. As shown in FIG. 4, an annular porous member 24 is disposed in the recess 17. The porous member 24 is disposed so as to surround the opening edge 25 of the hole 15. The porous member 24 may be bonded to the inner surface of the recess 17.

  And the metal plate 20 and the insertion part 21 couple | bonded with the inner surface 27 of the metal plate 20 are prepared. The insertion portion 21 includes a shaft portion 22 having one end connected to the metal plate 20 and a tip portion 23 connected to the other end of the shaft portion 22.

  The distal end portion 23 is formed in a tapered shape, and the diameter of the distal end portion 23 is formed so as to decrease as the distance from the shaft portion 22 increases.

  In other words, the tip portion 23 is connected to the end portion of the shaft portion 22, the insertion portion 21 is connected to the end portion of the tip portion 23, and the end portion of the insertion portion 21 is more outward than the shaft portion 22. It is formed to overhang. As a result, the end surface 30 of the insertion portion 21 is formed in an annular shape so as to surround the insertion portion 21. A concave portion 32 is formed in the end portion 33 of the distal end portion 23.

  In FIG. 5, the insertion portion 21 is pushed into the hole portion 15. When the distal end portion 23 is inserted into the hole portion 15, the distal end portion 23 is elastically deformed so that the volume of the concave portion 32 is reduced. The tip portion 23 is elastically deformed in this manner, so that the diameter of the tip portion 23 is reduced and the tip portion 23 can pass through the hole portion 15.

  When the tip 23 passes through the hole 15, the tip 23 is released from the external force applied from the inner surface of the hole 15, and the tip 23 returns to its original shape.

  In FIG. 5, the metal plate 20 is connected to the inner surface 27 of the metal plate 20 and inserted into the hole 15, and the porous member 24 disposed between the metal plate 20 and the lid 6. The internal pressure release valve 31 is formed.

  The outer diameter D1 of the shaft portion 22 is smaller than the inner diameter D2 of the hole portion 15. The inner diameter D3 of the porous member 24 is larger than the inner diameter D2 of the hole 15. The outer diameter D4 of the porous member 24 is larger than the inner diameter D3. The outer diameter D5 of the metal plate 20 is larger than the outer diameter D4 of the porous member 24. The outer diameter D5 of the metal plate 20 is slightly smaller than the inner diameter D7 of the opening edge of the recess 17. The outer diameter D6 of the end face 30 is larger than the inner diameter D2 of the hole 15.

  In a state where no external force is applied to the metal plate 20, the porous member 24 is elastically deformed, and the porous member 24 presses the metal plate 20 upward. When the metal plate 20 is pressed upward, the insertion portion 21 also tries to move upward. Since the outer diameter D 6 of the end surface 30 is larger than the inner diameter D 2 of the hole 15, the end surface 30 is in close contact with the lid 6 by the elastic force of the porous member 24.

  In addition, the porous member 24 is elastically deformed so as to shrink more than in the unloaded state, and the porous member 24 comes into close contact with the inner surface 27 of the metal plate 20 by the elastic force of the porous member 24 and is porous. The material member 24 comes into close contact with the lid 6 and closes the hole 15.

  As a result, in the state shown in FIG. 5, even if the internal pressure in the battery case 2 increases, the gas in the battery case 2 and the electrolyte solution 4 are suppressed from coming out of the battery case 2. Furthermore, moisture can be prevented from entering the battery case 2 from the outside of the battery case 2.

  For this reason, it is possible to reduce the necessity of performing the initial charging step S5 and the aging step S6 described below in a low-humidity atmosphere, and the manufacturing process of the secondary battery 1 can be simplified. As shown in FIG. 5, the metal plate 20 is located outside the lid 6 in a state where no external force is applied to the metal plate 20.

  As described above, in the state where the internal pressure release valve 31 seals the hole 15, the electrode body 3 is charged in step S5 of FIG. By this initial charging, the electrode body 3 and the electrolytic solution 4 chemically react to generate gas.

  Then, in step S6 of FIG. 3, after the electrode body 3 is initially charged, the battery case 2 is left for a predetermined period, and the battery case 2 is aged.

  Then, in step S7 of FIG. 3, the internal pressure release valve 31 is opened, and the gas in the battery case 2 is exhausted to the outside.

  FIG. 6 is a cross-sectional view showing the state of step S7. As shown in FIG. 7, the metal plate 20 is pressed. By pressing the metal plate 20, the porous member 24 is elastically deformed so as to shrink. As the porous member 24 contracts and the metal plate 20 moves so as to approach the lid 6, the end face 30 is separated from the lid 6.

  Thus, an exhaust passage that passes between the end face 30 and the lid 6, between the shaft portion 22 and the hole portion 15, between the porous member 24, and between the outer peripheral edge portion of the metal plate 20 and the opening edge portion of the concave portion 17. 35 is formed.

  Then, the gas in the battery case 2 passes through the exhaust passage 35 and is discharged to the outside of the battery case 2, so that the internal pressure in the battery case 2 decreases.

  Decreasing the internal pressure of the battery case 2 can suppress the explosion-proof valve 18 from being broken or the rigidity of the explosion-proof valve 18 from being lowered. Furthermore, the swelling of the battery case 2 can be reduced.

  Here, for example, when the electrolytic solution 4 is attached to the tip portion 23, the attached electrolytic solution 4 may enter between the shaft portion 22 and the hole portion 15 together with the gas ejected from the battery case 2. At this time, since the porous member 24 is provided in the exhaust passage 35, the electrolytic solution 4 is caught by the porous member 24, and the electrolytic solution 4 is suppressed from being discharged outside the battery case 2.

  The Gurley number of the porous member 24 is 50 (seconds) or less. This is because if the Gurley number is larger than 50, the time required for completing the exhaust of gas becomes longer, and the manufacturing time becomes longer. Preferably, a material having a Gurley number of 10 (seconds) or less is employed.

  The Young's modulus of the porous member 24 is 10 MPa or more and 100 MPa or less. For this reason, in order to form the exhaust passage 35 by pressing the metal plate 20, a load of a predetermined value or more is applied to the porous member 24.

  As a result, the surface pressure between the porous member 24 and the metal plate 20 and the surface pressure between the porous member 24 and the lid 6 become a predetermined value or more. Accordingly, the electrolytic solution 4 that has entered between the inner peripheral surface of the hole portion 15 and the outer peripheral surface of the shaft portion 22 is between the porous member 24 and the metal plate 20 or between the porous member 24 and the lid 6. It is possible to suppress discharge to the outside.

  When the Young's modulus of the porous member 24 is smaller than 10 MPa, the surface pressure between the porous member 24 and the metal plate 20 and the surface pressure between the porous member 24 and the lid 6 are reduced, and the electrolytic solution 4 Is likely to be discharged to the outside. In addition, when the Young's modulus of the porous member 24 is greater than 100 MPa, the load applied to the metal plate 20 to form the exhaust passage 35 increases and the work load increases.

  Note that, in the step S7 for removing the gas from the battery case 2, it may be performed in a low-pressure atmosphere. By carrying out in a low-pressure atmosphere, gas can be easily discharged from the battery case 2, and the process can be completed in a short time.

  FIG. 7 is a cross-sectional view showing step S8 of FIG. As shown in FIG. 7, the outer peripheral edge of the metal plate 20 and the opening edge of the recess 17 in a state where the metal plate 20 is pressed so that the outer surface 26 of the metal plate 20 and the lid 6 are flush with each other. Is irradiated with a laser beam L to form a welded portion 28 for welding the metal plate 20 and the lid 6.

  The welded portion 28 is formed over the entire periphery of the outer peripheral edge portion of the metal plate 20 and the opening edge portion of the concave portion 17. By this welded portion 28, the gap between the outer peripheral edge portion of the metal plate 20 and the opening edge portion of the concave portion 17 is closed, and the hole portion 15 is closed. And the closure part 16 shown in FIG. 2 is formed by the welding part 28 being formed.

  Here, in step S7, since the electrolyte solution 4 is suppressed from being ejected from the battery case 2, the adhesion of the electrolyte solution 4 to the welded portion is suppressed, and the welded portion 28 can be formed satisfactorily. . Accordingly, the sealing performance of the battery case 2 can be improved.

  In the above example, the internal pressure release valve 31 has been described as an example in which the porous member 24 and the metal plate 20 are provided separately. However, the porous member 24 is formed integrally with the metal plate 20. Also good.

  FIG. 8 is a side view showing a first modification of the internal pressure release valve 31, and FIG. 9 is a plan view of the internal pressure release valve 31 viewed from the direction of the arrow shown in FIG.

  As shown in FIGS. 8 and 9, the internal pressure release valve 31 </ b> A is formed integrally with the insertion portion 21 coupled to the metal plate 20 and the metal plate 20 and surrounds the periphery of the insertion portion 21. Porous member 24 formed. The porous member 24 is bonded and fixed to the metal plate 20.

  As shown in FIG. 5, the internal pressure release valve 31 </ b> A may be inserted into the hole 15 and the porous member 24 may be in close contact with the lid 6.

  According to the internal pressure release valve 31A, since the porous member 24 is integrally formed with the metal plate 20, the step of placing the porous member 24 in the recess 17 and the insertion portion 21 in the hole 15 are arranged. The process of inserting into the substrate can be performed at the same time, and the manufacturing process can be simplified.

  FIG. 10 is a side view showing a second modification of the internal pressure release valve, and FIG. 11 is a plan view when seen in a plan view from the direction of the arrow shown in FIG.

  As shown in FIGS. 10 and 11, the internal pressure release valve 31 </ b> B includes a metal plate 20, an insertion portion 21 formed on the metal plate 20, and an annular elastic member formed so as to surround the insertion portion 21. 42.

  The elastic member 42 includes an annular resin wall 41 in which a window portion 43 is formed, and a porous member 40 exposed to the outside from the window portion 43. The resin wall 41 is formed in a circular shape, and the window portion 43 includes an inner side surface 44 and an inner side surface 45 arranged in the circumferential direction of the resin wall 41.

  The porous member 40 is formed in a circular shape centered on the center O <b> 1, and most of the porous member 40 is embedded in the resin wall 41. And it forms so that a part of porous member 40 may be exposed outside from the window part 43. FIG. The inner side surfaces 44 and 45 are formed so as to extend in the radial direction of the circular porous member 40. The elastic member 42 thus formed is formed (fixed) on the metal plate 20 by a rubber molding die or the like.

  In FIG. 11, an example in which one window portion 43 is formed is illustrated, but a plurality of window portions 43 are formed so that the porous member 40 is exposed from each window portion 43. Yes.

  Moreover, it is not essential to form the porous member 40 in an annular shape, and the porous member 40 may be formed in an arc shape. In this case, both end portions of the porous member 40 are embedded in the resin wall 41.

  Also in the internal pressure release valve 31B shown in FIGS. 10 and 11, since the porous member 40 is formed integrally with the metal plate 20, the step of disposing the porous member 40 in the recess 17 and the insertion portion 21. Can be simultaneously performed in the hole 15, and the manufacturing process can be simplified.

  FIG. 12 is a table showing the results of comparing the airtightness of the secondary battery according to the comparative example and the secondary batteries according to Examples 1 to 3.

  Here, in the secondary battery of Example 1, as shown in FIG. 4, an internal pressure release valve 31 in which the porous member 24, the metal plate 20, and the insertion portion 21 are separated is mounted in the hole portion 15. The secondary battery when the metal plate 20 is welded.

  The secondary battery of Example 2 is a secondary battery when the internal pressure release valve 31A shown in FIGS. 8 and 9 is mounted in the hole 15 and the metal plate 20 is welded.

  The secondary battery of Example 3 is a secondary battery when the internal pressure release valve 31B shown in FIGS. 10 and 11 is mounted in the hole 15 and the metal plate 20 is welded.

  The structure of the secondary battery of the comparative example will be described with reference to FIGS. FIG. 13 is a perspective view showing an internal pressure release valve 31D used in the manufacturing process of the secondary battery of the comparative example. As shown in FIG. 13, the internal pressure release valve 31 </ b> D includes a metal plate 20, an insertion portion 21 formed on the inner surface 27 of the metal plate 20, and an annular support member formed so as to surround the insertion portion 21. 50.

  The support member 50 includes a base plate 51 that is tightly fixed to the inner surface 27 of the metal plate 20 and a plurality of protrusions 52 that are formed so as to protrude from the surface of the base plate 51. The protrusions 52 are formed at intervals.

  FIG. 14 is a cross-sectional view illustrating step S4 of the manufacturing process of the secondary battery of the comparative example. As shown in FIG. 14, the internal pressure release valve 31 </ b> D is mounted in the hole 15.

  At this time, the protrusion 52 is elastically deformed, and the distal end portion 23 of the insertion portion 21 is in close contact with the lid 6.

  FIG. 15 is a cross-sectional view showing step S7 of the manufacturing process of the secondary battery of the comparative example. As shown in FIG. 15, by pressing the metal plate 20, the gas in the battery case 2 is exhausted to the outside. An exhaust passage 35 is formed. And the internal pressure in the battery case 2 is reduced.

  FIG. 16 is a cross-sectional view showing step S8, in which the outer peripheral edge of the metal plate 20 is welded to the lid 6 to manufacture the secondary battery according to the comparative example.

  As shown in the table shown in FIG. 12, the secondary battery of the comparative example, the secondary battery of Example 1, the secondary battery of Example 2, and the secondary battery of Example 3 are each 20 in number. The battery case was evaluated for each secondary battery.

  Here, in the secondary battery which concerns on a comparative example, it turned out that there is a defect in airtightness in eight secondary batteries among 20 secondary batteries.

  As shown in FIG. 15, when the gas is exhausted to the outside, the electrolyte 4 in the battery case 2 is ejected to the outside and the laser shown in FIG. This is because the electrolyte solution 4 has adhered to the irradiation position of the light L. If laser welding is performed in a state where the electrolytic solution 4 adheres to the welded portion, the bead width is insufficient or the welded portion 28 is intermittently formed. As a result, in the secondary battery of the comparative example, a defect occurred in the airtightness.

  On the other hand, in the secondary battery of Examples 1-3, it turns out that there is no problem in airtightness. This is because in step S7, the electrolyte solution 4 can be prevented from being ejected to the outside, and the weld 28 can be formed satisfactorily.

  As mentioned above, although each embodiment based on this invention was described, each embodiment disclosed this time is an illustration and restrictive at no points. The technical scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a method for manufacturing a secondary battery.

  DESCRIPTION OF SYMBOLS 1 Secondary battery, 2 Battery case, 3 Electrode body, 4 Electrolyte, 5 Case main body, 6 Lid, 7, 28 Welded part, 10, 26 Outer surface, 11, 27 Inner surface, 12, 13 Terminal, 15 Hole part , 16 Closure member, 17, 32 Recessed part, 18 Explosion-proof valve, 20 Metal plate, 21, 21D Insertion part, 22 Shaft part, 23 Tip part, 24, 40 Porous member, 25 Open edge part, 30 End face, 31, 31A , 31B, 31D Internal pressure release valve, 33 end, 35 exhaust passage, 41 resin wall, 42 annular member, 43 window, 44, 45 inner surface, 50 support member, 51 base plate, 52 protrusion.

Claims (1)

A battery case including a lid part in which a hole is formed;
An electrode body and an electrolytic solution disposed in the battery case;
A closing member closing the hole;
A method for manufacturing a secondary battery comprising:
Welding the lid with the hole opened to a case body to form the battery case and disposing the electrode body in the battery case;
Injecting the electrolyte from the hole into the battery case;
Forming a pressure relief valve in the hole;
Charging the electrode body after forming the pressure relief valve;
Opening the pressure release valve so that the inside of the battery case and the outside of the battery case communicate with each other;
Welding the pressure relief valve to the lid to form the closure member;
The pressure release valve includes a metal plate disposed on the outer surface side of the lid portion, an insertion portion connected to the metal plate and inserted into the hole portion, and the metal plate and the lid. An annular elastic member provided between and surrounding the opening edge of the hole,
At least a part of the elastic member is formed of an elastically deformable porous member,
The insertion portion includes a shaft portion inserted into the hole portion, and a tip portion formed at an end portion of the shaft portion,
In a state in which no external force is applied to the metal plate, the tip portion is in close contact with the inner surface of the lid by the elastic force of the elastic member to close the hole portion,
When the metal plate is pressed toward the lid, the tip portion is separated from the inner surface, passes through the hole and the porous member, and communicates the inside of the battery case and the outside of the battery case. A ventilation passage is formed,
Opening the pressure release valve includes pressing the metal plate to form the vent passage;
The step of forming the closing member includes a step of welding the entire outer peripheral edge of the metal plate to the lid.

Images