JP2014049317A - Power storage device and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of suppressing deformation of a conductive member accompanied with performing resistance welding of a laminate to the conductive member, and also to provide a method for manufacturing the power storage device.SOLUTION: A positive electrode 23 has a positive electrode tab 23c preventing an active material from being coated on the surface on which the active material of a metal foil 23a is coated. A positive electrode tab group 26 composed in a layer form of the positive electrode tab 23c is welded and joined to a positive electrode conductive member 19 electrically connected to a positive electrode terminal by resistance welding. On the surface opposite to the surface to which the positive electrode tab group 26 is welded and joined in the positive electrode conductive member 19, a welded part 40 having electrical conduction property is welded and joined.

Description

  The present invention relates to a power storage device and a method for manufacturing the power storage device.

  Conventionally, lithium ion secondary batteries and nickel metal hydride secondary batteries are well known as power storage devices mounted on vehicles and the like. Such a secondary battery includes an electrode assembly in which an electrode obtained by applying an active material to a metal foil is laminated or wound to form a layer shape. In the electrode assembly, a laminated body is configured by laminating an uncoated portion where no active material is applied on a metal foil. And in a secondary battery, the laminated body and the electrode terminal exposed to the exterior of a case are electrically connected through the electrically-conductive member (for example, refer patent document 1).

  In the secondary battery described in Patent Document 1, in a state where both sides in the stacking direction of the laminate are sandwiched by the conductive member, the laminate and the laminate are energized between the electrode bars pressed from the outside of the conductive member. The conductive member is joined by resistance welding.

JP 2009-32640 A

  By the way, in said secondary battery, when joining a laminated body and a conductive member by resistance welding, a conductive member may fuse | fuse to an electrode bar. In this case, if the electrode rod is pulled away from the conductive member after the resistance welding is completed, the conductive member is pulled by the electrode rod to cause deformation, which may affect the battery performance of the secondary battery.

  This invention is made | formed in view of such a situation, The objective is suppressing that an electrical storage performance is affected by a conductive member deform | transforming in connection with resistance welding of a laminated body to a conductive member. An object of the present invention is to provide a power storage device and a method for manufacturing the power storage device.

  In order to solve the above-mentioned problem, the invention according to claim 1 is a state in which a separator is interposed between a positive electrode and a negative electrode each having a coating part in which an active material is applied to at least one surface of a metal foil. A power storage device comprising a layered electrode assembly and an electrode terminal for transferring electricity to and from the electrode assembly, wherein the positive electrode and the negative electrode are coated with an active material of the metal foil A laminated body having an uncoated portion to which an active material is not applied on the formed surface, and the uncoated portion being formed in a layer shape is electrically connected to both the electrode assembly and the electrode terminal. The conductive member is welded by resistance welding, and a welded portion having electrical conductivity is welded to the surface of the conductive member opposite to the surface on which the laminate is welded. This is the gist.

  According to this, when performing resistance welding between the laminate and the conductive member while bringing the main body of the electrode rod into contact with the conductive member via the welded portion, the electrode rod is separated from the conductive member after the resistance welding is completed. If it is going to be, since the welding part currently interposed between the main-body part and the electrically-conductive member is weld-joined by the electrically-conductive member, it will isolate | separate from a main-body part. For this reason, when the electrode bar is pulled away from the conductive member, it is possible to suppress a force from acting on the conductive member from the electrode bar. Therefore, it is possible to suppress the storage performance from being affected by the deformation of the conductive member accompanying resistance welding of the laminate to the conductive member.

  According to a second aspect of the present invention, in the power storage device according to the first aspect, the area of the joint surface of the welded portion with the conductive member is greater than the area of the surface of the welded portion opposite to the joint surface. Is also small.

  According to this, when performing resistance welding between the laminate and the conductive member while bringing the main body portion of the electrode rod into contact with the surface of the welded portion opposite to the joint surface with the conductive member, the conductive member at the welded portion is used. The area of the joint surface is smaller than the area of the contact surface with the main body portion in the welded portion. Therefore, when the conductive member is energized through the welded portion from the main body portion, a current flows locally from the welded portion to the conductive member, so that the welded portion is reliably welded to the conductive member. As a result, when the electrode rod is pulled away from the conductive member, the welded portion is stably separated from the main body portion. Therefore, it can further suppress that a conductive member deform | transforms in connection with resistance welding a laminated body to a conductive member.

  A third aspect of the present invention is the power storage device according to the first or second aspect, wherein a concave portion is provided on a surface of the welded portion opposite to a joint surface with the conductive member. And

  According to this, when the main body portion of the electrode rod is fitted into the concave portion of the welded portion, resistance welding between the laminate and the conductive member is stably performed. In this case, even if the recessed portion is provided in the welded portion, the size of the outer shape of the welded portion does not increase. Therefore, when the welded portion is welded to the conductive member, the size of the occupied area occupied by the welded portion in the electrode assembly does not change, and the increase in size of the electrode assembly can be suppressed.

  The invention according to claim 4 is the power storage device according to any one of claims 1 to 3, wherein the welding portion is made of the same material as the conductive member. .

  According to this, when performing resistance welding between the laminate and the conductive member while bringing the main body portion of the electrode rod into contact with the conductive member via the welded portion, the welded portion is securely welded to the conductive member. The As a result, when the electrode rod is pulled away from the conductive member, the welded portion is stably separated from the main body portion. Therefore, it can further suppress that a conductive member deform | transforms in connection with resistance welding a laminated body to a conductive member.

The invention according to claim 5 is the power storage device according to any one of claims 1 to 4, wherein the power storage device is a secondary battery.
The invention according to claim 6 is an electrode assembly in which a separator is interposed between a positive electrode and a negative electrode each having a coating portion in which an active material is applied to at least one surface of a metal foil. A solid body and an electrode terminal for transferring electricity between the electrode assembly, and the positive electrode and the negative electrode are not coated with an active material on the surface of the metal foil on which the active material is applied And a laminate formed by laminating the uncoated part is welded and joined by resistance welding to a conductive member electrically connected to both the electrode assembly and the electrode terminal. A method of manufacturing a power storage device, wherein a contact portion of the conductive member opposite to a surface on which the laminate is welded is brought into contact with a welded portion having electrical conductivity and separable from the welded portion The body part of the configured electrode rod is connected to the welded part. A welding process in which the laminate and the conductive member are welded by resistance welding in a state of being pressed against a surface opposite to a joint surface with the conductive member, and the main body from the welded portion used in the welding process. And a separation step for separating the parts.

  When performing resistance welding between the laminate and the conductive member while bringing the main body portion of the electrode rod into contact with the conductive member via the welded portion, the welded portion interposed between the main body portion and the conductive member is the conductive member. May be welded together. In this regard, according to this, since the main body is configured to be separable from the welded portion, when the main body is separated from the conductive member after the resistance welding is completed, the welded portion welded to the conductive member is Separated from the main body. Therefore, when a main body part is pulled away from a conductive member, it is suppressed that force acts on a conductive member from a main body part. Therefore, it is possible to suppress the storage performance from being affected by the deformation of the conductive member accompanying resistance welding of the laminate to the conductive member.

  According to a seventh aspect of the present invention, in the method of manufacturing a power storage device according to the sixth aspect, in the welding step, the welded portion is brought into contact with the conductive member in a state where the welded portion is held by the main body portion. This is the gist.

  According to this, resistance welding between the laminate and the conductive member can be easily performed by energizing the conductive member through the welded portion from the main body portion while bringing the welded portion held by the main body portion of the electrode rod into contact with the conductive member. Can be done.

  ADVANTAGE OF THE INVENTION According to this invention, it can suppress that an electrical storage performance is affected by a conductive member deform | transforming in connection with resistance welding of a laminated body to a conductive member.

The disassembled perspective view of the secondary battery in embodiment. Sectional drawing which shows the electrode assembly inserted in the case. The disassembled perspective view which shows the component of an electrode assembly. Sectional drawing which shows typically the welding state of a positive electrode tab group and a positive electrode electrically-conductive member. Sectional drawing which shows the state before an electrode bar contacts a positive electrode tab group and a positive electrode electrically-conductive member. Sectional drawing which shows the state which the electrode rod contacted the positive electrode tab group and the positive electrode electrically-conductive member. Sectional drawing which shows the state in which the welding site | part was formed in the positive electrode tab group. Sectional drawing which shows the state in which the electrode rod has left | separated from the positive electrode tab group and the positive electrode electrically-conductive member. Sectional drawing which shows typically the welding state of the positive electrode tab group of another example, and a positive electrode electrically-conductive member.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, an electrode assembly 12 is accommodated in a case 11 made of aluminum in a secondary battery 10 as a power storage device. The case 11 includes a case main body 13 having a rectangular box shape and a lid member 14 having a rectangular flat plate shape that closes the opening 13 a of the case main body 13. In addition, the secondary battery 10 of this embodiment is a square battery whose outer shape forms a square shape. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

  As shown in FIGS. 1 and 2, the electrode assembly 12 is electrically connected to a positive terminal 15 as an electrode terminal for transferring electricity to and from the electrode assembly 12 and a negative terminal 16 as an electrode terminal. It is connected to the. The positive electrode terminal 15 and the negative electrode terminal 16 are exposed to the outside of the case 11 through a pair of opening holes 14 a arranged in parallel with the lid member 14 at a predetermined interval. Insulating rings 17 and 18 for electrically insulating the terminals 15 and 16 and the case 11 are attached to the positive terminal 15 and the negative terminal 16, respectively. The electrode assembly 12 is electrically connected to the positive electrode terminal 15 via the positive electrode conductive member 19 and is electrically connected to the negative electrode terminal 16 via the negative electrode conductive member 20. That is, the positive electrode conductive member 19 is electrically connected to both the electrode assembly 12 and the positive electrode terminal 15, while the negative electrode conductive member 20 is electrically connected to both the electrode assembly 12 and the negative electrode terminal 16. Connected. The positive electrode conductive member 19 and the negative electrode conductive member 20 are both plate-shaped members. Insulating sheets 21 and 22 for electrically insulating the electrode assembly 12 from the case main body 13 and the lid member 14 are attached to the inner surface of the case main body 13 and the inner surface of the lid member 14.

  As shown in FIG. 3, the electrode assembly 12 has a sheet-like positive electrode 23 having an active material layer 23b as a coating portion in which an active material is applied to both surfaces of a metal foil 23a, and both surfaces of the metal foil 24a. The sheet-like negative electrode 24 having an active material layer 24b as a coating portion coated with the active material is laminated with a sheet-like separator 25 interposed therebetween.

  In the positive electrode 23, a positive electrode tab 23 c that is an uncoated portion where the active material is not applied in the metal foil 23 a protrudes from one side of the active material layer 23 b in the positive electrode 23. Similarly, in the negative electrode 24, a negative electrode tab 24 c that is an uncoated portion where the active material is not applied in the metal foil 24 a protrudes from one side of the active material layer 24 b in the negative electrode 24. The positive electrode 23 and the negative electrode 24 are stacked in a state where the positive electrode tab 23c and the negative electrode tab 24c do not overlap.

  As shown in FIG. 1, each positive electrode tab 23 c is collected in a range from one end to the other end in the stacking direction of the electrode assembly 12 and is layered to form a positive electrode tab group 26 as a stacked body. It is composed. A metal positive electrode conductive member 19 electrically connected to the positive electrode terminal 15 is joined to the positive electrode tab group 26 by resistance welding. Similarly, each negative electrode tab 24c is collected in a range from one end to the other end of the electrode assembly 12 in the stacking direction and is layered to form a negative electrode tab group 27 as a stacked body. Yes. A metal negative electrode conductive member 20 electrically connected to the negative electrode terminal 16 is joined to the negative electrode tab group 27 by resistance welding.

  More specifically, as shown in FIG. 4, the positive electrode tab group 26 includes a bent portion 30 that curves to the side opposite to the side to which the positive electrode conductive member 19 is joined, and an extension that extends from the bent portion 30 in the stacking direction. Part 31. That is, the positive electrode conductive member 19 has a positive electrode tab 23c (the left side in FIG. 4) whose positive electrode tab 23c is located on the outermost side in the bending direction of the bent portion 30 of the positive electrode tab group 26. The positive electrode tab is welded in a state of contact. The positive electrode conductive member 19 is welded to the positive electrode tab group 26 in a state parallel to the end surface of the electrode assembly 12 from which the positive electrode tab 23 c protrudes.

  Similarly, the negative electrode tab group 27 is curved to the side opposite to the side to which the negative electrode conductive member 20 is bonded, and the negative electrode conductive member 20 is the negative electrode tab 24c of the negative electrode tab group 27. The group 27 is welded in contact with the negative electrode tab 24c located on the outermost side in the bending direction. Further, the negative electrode conductive member 20 is welded to the negative electrode tab group 27 in a state parallel to the end surface of the electrode assembly 12 from which the negative electrode tab 24 c protrudes.

  Note that resistance welding is a method in which the objects to be joined are welded by being sandwiched between a pair of positive and negative electrode electrodes for welding. As shown in FIGS. 1 and 2, in this embodiment, the tip portions of the welding electrode rods pressed against the conductive members 19 and 20 during resistance welding are welded portions 40 and 41, respectively. , 20. Moreover, in this embodiment, the welding parts 40 and 41 are comprised with the metal material which has the electrical conductivity used as each conductive member 19 and 20, and becomes the same material.

  In this case, the weld 40 is welded to the surface of the positive electrode conductive member 19 opposite to the surface to which the positive electrode tab group 26 is welded. The weld 40 is located in the end face of the positive electrode conductive member 19 as viewed from the end face side from which the positive electrode tab 23 c protrudes in the electrode assembly 12.

  Further, the welded portion 41 is welded to the surface of the negative electrode conductive member 20 opposite to the surface to which the negative electrode tab group 27 is welded. The welded portion 41 is located in the end surface of the negative electrode conductive member 20 as viewed from the end surface side where the negative electrode tab 24 c protrudes in the electrode assembly 12.

  Next, in the manufacturing process of the secondary battery 10, after the electrode tab groups 26 and 27 are configured by stacking the electrode tabs 23 c and 24 c by superimposing the positive electrode 23 and the negative electrode 24, A welding process when welding the groups 26 and 27 and the conductive members 19 and 20 will be described. Since the welding process between the positive electrode tab group 26 and the positive electrode conductive member 19 is the same as the welding process between the negative electrode tab group 27 and the negative electrode conductive member 20, the welding process between the positive electrode tab group 26 and the positive electrode conductive member 19 will be described below. explain.

  First, as shown in FIG. 5, the positive electrode tab group 26 is collected by collecting the positive electrode tabs 23c from one end side (right side in FIG. 5) to the other end side (left side in FIG. 5) of the electrode assembly 12 in the stacking direction. Configure. Then, the positive electrode conductive member 19 is brought into contact with the positive electrode tab 23 c on the other end side in the stacking direction in the positive electrode tab group 26. In addition, a pair of positive and negative electrode rods 50 and 51 are arranged at positions facing each other across the portion to be welded in the positive electrode tab group 26.

  In this case, the positive electrode rod 50 (left electrode rod in FIG. 5) has a main body 52 and a weld 40 configured to be separable from the main body 52. In addition, a circular recess 53 is formed in the end surface 40 a that contacts the end surface 52 a of the main body 52 in the welded portion 40. The columnar convex portion 54 formed on the end surface 52 a of the main body portion 52 is unevenly fitted to the concave portion 53 of the welded portion 40, so that the welded portion 40 is held by the main body portion 52.

  Then, as a welding process, as shown in FIG. 6, in a state where a portion to be welded is pressed in the positive electrode tab group 26 by a pair of positive and negative electrode rods 50, 51, between these electrode rods 50, 51. Apply voltage. Then, as indicated by a dotted arrow in FIG. 7, a current flows from the positive electrode rod 50 toward the negative electrode rod 51 through the positive electrode conductive member 19 and the positive electrode tab group 26.

  When a predetermined time elapses after the voltage is applied between the pair of electrode rods 50 and 51 and the positive electrode tab group 26 is welded to the positive electrode conductive member 19 by the welding portion P, the positive electrode tab group 26, resistance welding to the positive electrode conductive member 19 is completed.

  Thereafter, as a separation step, as shown in FIG. 8, the pair of electrode bars 50 and 51 are separated from the positive electrode conductive member 19 and the positive electrode tab group 26. In this case, in the electrode rod 50 on the positive electrode side, the welded portion 40 that was interposed between the main body portion 52 and the positive electrode conductive member 19 is welded to the positive electrode conductive member 19, so that it is separated from the main body portion 52. The

Next, the operation of the secondary battery 10 configured as described above will be described.
The positive electrode conductive member 19 in the secondary battery 10 of the present embodiment has a positive electrode rod 50 due to a current flowing between the pair of electrode rods 50, 51 during resistance welding of the positive electrode tab group 26. The welded portion 40 interposed between the main body portion 52 and the main body portion 52 is welded.

  The welded portion 40 has a tapered shape toward the distal end side, and the distal end surface 40b opposite to the end surface 40a in the welded portion 40 is smoothly curved into a substantially spherical shape. Therefore, the area of the contact surface S <b> 1 that contacts the positive electrode conductive member 19 on the distal end surface 40 b of the welded portion 40 is smaller than the area of the end surface 40 a on the proximal end side that contacts the main body portion 52 in the welded portion 40.

  Therefore, when the pair of positive and negative electrode rods 50 and 51 presses a portion to be welded in the positive electrode tab group 26, the electrode rod 50 is positively conductive on the contact surface S1 with the positive electrode conductive member 19 in the welded portion 40. The load at the time of pressing against the member 19 is concentrated. Moreover, in the electrode rod 50 on the positive electrode side, the current flowing from the main body portion 52 to the welded portion 40 through the end surface 40a is concentrated on the contact surface S1 with the positive electrode conductive member 19 in the welded portion 40.

  That is, the current acts locally on the contact surface S1 of the welded portion 40 with the positive electrode conductive member 19 together with the load. As a result, the contact portion of the positive electrode conductive member 19 with the weld 40 is easily melted. Therefore, the weld 40 is reliably welded to the positive electrode conductive member 19.

  On the other hand, the welded portion 40 is in contact with the main body portion 52 via an end surface 40a having a larger area than the contact surface S1 with the positive electrode conductive member 19. Therefore, the area of the contact interface between the main body portion 52 and the welded portion 40 is set to be relatively large. As a result, current and load act on the contact interface between the main body 52 and the weld 40 in a distributed manner. Therefore, at the time of resistance welding, the main body portion 52 and the welded portion 40 are hardly fused at the contact interface between the main body portion 52 and the welded portion 40.

  In addition, also in the electrode rod 51 on the negative electrode side, the tip portion 51a that contacts the positive electrode tab group 26 has a tapered shape. Therefore, the current flowing from the positive electrode tab group 26 locally acts on the contact surface S2 that contacts the positive electrode tab group 26 at the tip 51a of the electrode bar 51 together with the load. However, in this embodiment, the heat capacity of the positive electrode tab group 26 is larger than the heat capacity of the positive electrode conductive member 19, and the electric resistance of the positive electrode tab group 26 is smaller than the electric resistance of the positive electrode conductive member 19. Therefore, even if a current or a load is concentrated on the contact portion of the positive electrode tab group 26 with the tip 51a of the electrode bar 51, the amount of heat generated by the electrical resistance at the contact portion is small, and the temperature associated with the heat generation at the contact portion. Change is small. As a result, the contact portion of the positive electrode tab group 26 with the tip 51a of the electrode bar 51 is difficult to melt during resistance welding, and the tip 51a of the electrode bar 51 is difficult to be welded to the positive electrode tab group 26.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) The welded portions 40 and 41 of the electrode rod 50 are welded to the conductive members 19 and 20 during resistance welding. On the other hand, in the electrode rod 50, the main body 52 and the welded portions 40 and 41 are difficult to fuse at the contact interface between the two during resistance welding. Therefore, when the electrode rod 50 is to be separated from the conductive members 19 and 20 after the resistance welding is completed, the welded portions 40 and 41 of the electrode rod 50 are separated from the main body portion 52. As a result, when the electrode bar 50 is pulled away from the conductive members 19 and 20, it is suppressed that a force acts on the conductive members 19 and 20 from the electrode bar 50. Therefore, it is possible to suppress the battery performance of the secondary battery 10 from being affected by the deformation of the conductive members 19 and 20 due to the resistance welding of the electrode tab groups 26 and 27 to the conductive members 19 and 20. .

  (2) The area of the contact surface S1 with the respective conductive members 19 and 20 in the welded portions 40 and 41 is smaller than the area of the end surface opposite to the contact surface S1 in the welded portions 40 and 41. Therefore, when resistance welding is performed, current and load locally act on the contact surfaces S1 of the welded portions 40 and 41 with the conductive members 19 and 20, so that the welded portions 40 and 41 are connected to the conductive members 19 and 20 respectively. Reliably welded. As a result, the welded portions 40 and 41 are stably separated from the main body portion 52 when the electrode rod 50 is pulled away from the conductive members 19 and 20. Therefore, it is possible to further suppress deformation of the conductive members 19 and 20 due to resistance welding of the electrode tab groups 26 and 27 to the conductive members 19 and 20. Moreover, it can suppress that the welding parts 40 and 41 peel from each electrically-conductive member 19 and 20 after the secondary battery 10 is assembled.

  (3) The recessed part 53 is provided in the end surface on the opposite side to contact surface S1 with each electroconductive member 19 and 20 in the welding parts 40 and 41. As shown in FIG. Accordingly, by fitting the convex portion 54 provided on the main body portion 52 of the electrode rod 50 into the concave portion 53 of the welding portions 40 and 41, resistance welding between the electrode tab groups 26 and 27 and the conductive members 19 and 20 is performed. Can be performed stably. In this case, even if the recessed portions 53 are provided in the welded portions 40 and 41, the size of the outer shape of the welded portions 40 and 41 does not increase, so that the increase in size of the electrode assembly 12 can be suppressed.

  (4) Since the welded portions 40 and 41 and the respective conductive members 19 and 20 are made of the same material, the welded portions 40 and 41 and the respective conductive members 19 and 20 are fused during resistance welding. The welded portions 40 and 41 are easily welded to the respective conductive members 19 and 20 easily. Therefore, since the welded portions 40 and 41 are stably separated from the main body portion 52, the conductive members 19 and 20 are deformed as the electrode tab groups 26 and 27 are resistance-welded to the conductive members 19 and 20, respectively. This can be further suppressed.

  (5) The welded portions 40 and 41 are brought into contact with the conductive members 19 and 20 while the welded portions 40 and 41 are held on the main body portion 52 of the electrode rod 50. Therefore, resistance welding between the electrode tab groups 26 and 27 and the conductive members 19 and 20 can be easily performed.

  (6) Metal welds 40 and 41 are welded to the respective conductive members 19 and 20. As a result, the heat capacity of each of the conductive members 19 and 20 is increased by the heat capacity of the welded portions 40 and 41 as compared with the case where the welded portions 40 and 41 are not welded. For this reason, when current flows through the conductive members 19 and 20 during charging and discharging of the secondary battery 10, it is possible to reduce temperature changes that occur in the conductive members 19 and 20.

In addition, you may change embodiment as follows.
In the embodiment, as shown in FIG. 9, the positive electrode conductive member 19 has the curved portion of the positive electrode tab group 23 c that constitutes the positive electrode tab group 26 at the innermost side in the bending direction of the bent portion 30 in the positive electrode tab group 26. You may weld to the positive electrode tab 23C (FIG. 9 right-side positive electrode tab) located. In this case, the welding part 40 is arrange | positioned in the space area R formed inward by bending the positive electrode tab group 26. FIG. Similarly, the negative electrode conductive member 20 is welded to the negative electrode tab 24 c that is located on the innermost side in the bending direction of the bending portion 30 in the negative electrode tab group 27 among the negative electrode tabs 24 c constituting the negative electrode tab group 27. May be.

  In the embodiment, the welded portions 40 and 41 may be made of a material different from that of the conductive members 19 and 20. In this case, the conductive members 19 and 20 are configured as materials constituting the welded portions 40 and 41 in order to reliably weld and join the welded portions 40 and 41 and the conductive members 19 and 20 during resistance welding. It is desirable to select a material having a melting point close to that of the material.

  In the embodiment, the electrode rod 50 may be provided with a convex portion on the end surface that contacts the main body portion 52 in the welded portions 40 and 41. In this case, the concave portions formed on the end surface of the main body portion 52 are fitted to the convex portions of the weld portions 40 and 41, whereby the weld portions 40 and 41 are held by the main body portion 52.

  In embodiment, the holding mechanism which hold | maintains the welding parts 40 and 41 in the main-body part 52 in the electrode rod 50 is not limited to the fitting structure by an unevenness | corrugation. For example, it is good also as a structure which provides a magnet in the end surface which contacts the welding parts 40 and 41 in the main-body part 52, and hold | maintains the welding parts 40 and 41 in the main-body part 52 with the magnetic force of this magnet. In that case, the whole or part of the welds 40 and 41 needs to be magnetic. Further, the welded portions 40 and 41 may be mechanically fixed and held with respect to the main body portion 52 by a clamp mechanism.

  In embodiment, it is good also as a structure by which the welding parts 40 and 41 are not hold | maintained at the main-body part 52 in the electrode rod 50 in the case of resistance welding. That is, during resistance welding, after placing the welded portions 40 and 41 on the welding target portions of the conductive members 19 and 20, the main body 52 is pressed against the placed welded portions 40 and 41. Also good.

  In the embodiment, the welded portions 40 and 41 are not necessarily configured to be tapered toward the distal end side. For example, you may comprise the shape of the welding parts 40 and 41 in the column shape which has fixed thickness in a length direction. In this case, the area of the contact surface S1 with the respective conductive members 19 and 20 in the welded portions 40 and 41 is the area of the end surface opposite to the contact surface S1 with the respective conductive members 19 and 20 in the welded portions 40 and 41. Will be equal.

  In the embodiment, after the electrode tab groups 26 and 27 and the conductive members 19 and 20 are resistance welded, the electrode assembly 12 is accommodated in the case 11 after the electrode tab groups 26 and 27 are bent. However, the electrode assembly 12 may be accommodated in the case 11 without bending the electrode tab groups 26 and 27 after resistance welding.

In the embodiment, the present invention is applied to the laminated secondary battery 10, but may be applied to a wound secondary battery in which a belt-like positive electrode and a belt-like negative electrode are wound and laminated in layers.
In the embodiment, the secondary battery 10 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery such as nickel metal hydride.

  The power storage device is not limited to the secondary battery 10 and may be a capacitor such as an electric double layer capacitor or a lithium ion capacitor.

  S1... Contact surface as bonding surface, 10... Secondary battery as power storage device, 12... Electrode assembly, 19... Positive electrode conductive member as conductive member, 20. 23a ... Metal foil, 23b ... Active material layer as coating part, 24 ... Negative electrode, 24a ... Metal foil, 24b ... Active material layer as coating part, 25 ... Separator, 26 ... Positive electrode tab group as laminate 27 ... Negative electrode tab group as a laminated body, 40, 41 ... Welded part, 50 ... Electrode rod, 52 ... Main part, 53 ... Recessed part.

Claims (7)

An electrode assembly configured in a layered manner with a separator interposed between a positive electrode and a negative electrode having a coating portion coated with an active material on at least one surface of a metal foil, and the electrode assembly A power storage device comprising electrode terminals for transferring electricity between them,
The positive electrode and the negative electrode have a non-coated portion where the active material is not applied on the surface of the metal foil applied with the active material, and the uncoated portion is formed in a layered structure. It is welded and joined by resistance welding to a conductive member electrically connected to both the electrode assembly and the electrode terminal,
A power storage device, wherein a welded portion having electrical conductivity is welded to a surface of the conductive member opposite to a surface to which the laminate is welded. The power storage device according to claim 1, wherein an area of a joint surface with the conductive member in the welded portion is smaller than an area of a surface of the welded portion on the opposite side to the joint surface. The power storage device according to claim 1, wherein a concave portion is provided on a surface of the welded portion opposite to a joint surface with the conductive member. The power storage device according to any one of claims 1 to 3, wherein the welding portion is made of the same material as the conductive member. The power storage device according to any one of claims 1 to 4, wherein the power storage device is a secondary battery. An electrode assembly layered in a state in which a separator is interposed between a positive electrode and a negative electrode having a coating portion in which an active material is applied to at least one surface of a metal foil, and the electrode assembly The positive electrode and the negative electrode have an uncoated portion where the active material is not applied to the surface of the metal foil on which the active material is applied, and the uncoated A method of manufacturing a power storage device in which a laminated body having a layered portion is welded and joined to a conductive member electrically connected to both the electrode assembly and the electrode terminal by resistance welding. ,
A main body portion of an electrode rod configured to contact a welded portion having electrical conductivity with a surface opposite to a surface on which the laminate is welded and joined in the conductive member, and to be separable from the welded portion, A welding step of welding the laminate and the conductive member by resistance welding in a state of being pressed against a surface opposite to the joint surface with the conductive member in the weld portion;
And a separation step of separating the main body portion from the weld portion used in the welding step. The method for manufacturing a power storage device according to claim 6, wherein in the welding step, the welded portion is brought into contact with the conductive member in a state where the welded portion is held by the main body portion.