JP2014056672A - Power storage device and manufacturing method of power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device in which, at a position away from a contact part for contacting a resistance-welding electrode, a metal exposed part group in which metal exposed parts of an electrode are overlapped in a layered manner, and an electrode terminal can be welded, and a manufacturing method of the power storage device.SOLUTION: A positive electrode collector tab group 24a in which positive electrode collector tabs 24 exposing positive electrode metal foils 21 are overlapped in a layered manner includes a contact part 33 to which a welding electrode 32 is contacted, and a press-contact part 35 in which the positive electrode collector tabs 24 constituting the positive electrode collector tab group 24a are press-contacted with each other. The press-contact part 35 is provided at such a position that at least a portion in the press-contact part 35 is not overlapped with the contact part 33, and welded with a positive electrode conductive member 30 in at least a portion that is not overlapped with the contact part 33, in the press-contact part 35.

Description

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

  Conventionally, lithium-ion secondary batteries, nickel-hydrogen secondary batteries, and the like are well known as power storage devices mounted on vehicles such as EVs (Electric Vehicles) and PHVs (Plug-in Hybrid Vehicles). In these secondary batteries, an electrode assembly is formed by laminating or winding an electrode in which an active material layer is formed on the surface of a metal foil with a separator interposed therebetween, and the like. Some electrode assemblies are housed in cases in which electrode terminals are fixed.

  In Patent Document 1, for example, when welding an exposed portion of a metal foil projecting from an edge portion of an electrode in an electrode assembly in a layered manner and an electrode terminal by resistance welding, resistance welding is performed. A small hole or the like penetrating the metal exposed portion group is provided in advance at the portion in contact with the electrode to enhance conductivity, and resistance welding between the metal exposed portion group and the electrode terminal is facilitated.

JP 2006-326622 A

  By the way, in the recent secondary battery, the working space in the case is reduced from the viewpoint of improving the energy density as the secondary battery, and the metal exposed portion group and the electrode terminal are resisted as in Patent Document 1. It may be difficult to bring the resistance welding electrode into contact with the portion to be welded.

  The present invention has been made paying attention to the problems existing in the above prior art, and its purpose is that the exposed metal portion of the electrode is layered at a position separated from the contact portion where the electrode for resistance welding is brought into contact. An object of the present invention is to provide a power storage device capable of welding overlapping metal exposed portion groups and electrode terminals, and a method for manufacturing the power storage device.

  In order to solve the above-mentioned problem, the invention described in claim 1 includes an electrode in which an active material layer is formed on a surface of a metal foil, and a separator that insulates between the electrodes, and the electrode is interposed between the separators. A power storage device comprising: an electrode assembly that is layered in an interposed state; and a case that accommodates the electrode assembly and has an electrode terminal fixed thereto, wherein the electrode assembly is a metal among the electrodes. The metal exposed portion group in which the metal exposed portion where the foil is exposed overlaps in layers, and the metal exposed portion group includes a contact portion to which an electrode for resistance welding is contacted, and a metal exposed portion constituting the metal exposed portion group A pressure-contact portion in which the portions are pressed against each other, and the pressure-contact portion is provided at a position where at least a part of the pressure-contact portion does not overlap the contact portion, and at least the contact portion of the pressure-contact portion It ’s the same as the club It is summarized as being welded to the electrode terminal in the portion.

  According to this, since the electric resistance is lower in the press-contact portion where the metal exposed portions are press-contacted with each other than the portion other than the press-contact portion, the current supplied from the resistance welding electrode in contact with the contact portion Flows preferentially through the pressure contact portion provided at a position where at least a portion does not overlap the contact portion, and as a result, resistance welding is performed at the pressure contact portion. Therefore, the metal exposed portion group and the electrode terminal can be resistance-welded and electrically connected at a position away from the contact portion with which the electrode for resistance welding is brought into contact.

  According to a second aspect of the present invention, in the power storage device according to the first aspect, the press contact portion is provided along an inner peripheral surface of the hole. According to this, a press-contact part can be simply provided along the inner peripheral surface of a hole by pushing a metal exposure part group into a hole shape by punching etc., for example.

  According to a third aspect of the present invention, in the power storage device according to the first aspect, the press contact portion is provided along a cut portion extending from an edge portion of the metal exposed portion group toward the contact portion. According to this, the electrical resistance when resistance welding is performed, that is, the strength of welding, can be adjusted by adjusting the cutting distance from the edge.

  According to a fourth aspect of the present invention, in the power storage device according to any one of the first to third aspects, the press-contact portion is provided at a position where the entire press-contact portion does not overlap the contact portion. According to this, even if it is a position away from the contact part, the metal exposed part group and the electrode terminal can be welded by resistance welding.

  According to a fifth aspect of the present invention, in the power storage device according to any one of the first to fourth aspects, the power storage device is a secondary battery. According to this, in the secondary battery, the metal exposed portion group in which the metal exposed portion of the electrode overlaps in layers can be welded at a position away from the contact portion where the resistance welding electrode is brought into contact.

  The invention according to claim 6 has an electrode in which an active material layer is formed on the surface of a metal foil, and a separator that insulates between the electrodes, and the electrode overlaps in layers with the separator interposed therebetween. An electrode assembly, and a case in which the electrode assembly is accommodated and an electrode terminal is fixed. The electrode assembly includes a metal exposed portion in which a metal exposed portion of the electrode where the metal foil is exposed overlaps in a layered manner A method of manufacturing a power storage device having a group, wherein a contact step of contacting metal exposed portions constituting the metal exposed portion group and a position where at least a part of the metal exposed portions are in contact with each other are not overlapped. A current is applied in a state where an electrode for resistance welding is in contact with a certain contact portion, and at least a portion where the exposed metal portions are in contact with each other does not overlap with the contact portion. And summarized in that comprises a step.

  According to this, since the electrical resistance is lower in the portion where the metal exposed portions are in contact with each other than in the portion other than the contacted portion, it is supplied from the resistance welding electrode in contact with the contact portion. The current flows preferentially at a location where the exposed metal portions where at least a portion does not overlap the contact portion are in contact with each other, and as a result, resistance welding is performed at the location where the exposed metal portions are in contact with each other. Therefore, the metal exposed portion group and the electrode terminal can be resistance-welded and electrically connected at a position away from the contact portion with which the electrode for resistance welding is brought into contact.

  ADVANTAGE OF THE INVENTION According to this invention, the metal exposure part group and electrode terminal which the metal exposure part of an electrode overlaps in layers can be welded in the position spaced apart from the contact part which contacts the electrode for resistance welding.

Sectional drawing which shows a lithium ion secondary battery typically. The perspective view which shows an electrode assembly typically. FIG. 1 is a sectional view taken along line 1-1 shown in FIG. (A) is the front view which expands and shows typically the positive electrode current collection tab group in another embodiment, (b) is 2-2 sectional view taken on the line shown to (a). (A) is the front view which expands and shows typically the positive electrode current collection tab group in another embodiment, (b) is 3-3 sectional drawing shown to (a).

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, in a lithium ion secondary battery (hereinafter referred to as “secondary battery”) 10 as a power storage device mounted on a vehicle, an electrode assembly 12 is accommodated in a case 11. The case 11 includes a bottomed rectangular box-shaped main body member 11a that houses the electrode assembly 12, and a rectangular plate-shaped lid member 11b that closes an opening of the main body member 11a. The main body member 11a and the lid member 11b are made of a metal such as stainless steel or aluminum.

  The case 11 is filled with a nonaqueous electrolytic solution 13 as an electrolyte. A positive electrode terminal 15 and a negative electrode terminal 16 are fixed to the lid member 11b which is one of the walls forming the case 11, and protrudes outward. The electrode assembly 12 is accommodated in the case 11 in a state of being covered with an insulating sheet 14 formed of an insulating resin.

  As shown in FIG. 2, the electrode assembly 12 includes a positive electrode sheet 18 as an electrode (positive electrode), a negative electrode sheet 19 as an electrode (negative electrode) having a polarity different from that of the positive electrode sheet 18, and a positive electrode sheet 18 and a negative electrode sheet 19. And a rectangular sheet-like separator 20 that insulates between the two. The electrode assembly 12 is a stacked electrode assembly in which a plurality of positive electrode sheets 18 and a plurality of negative electrode sheets 19 are stacked so as to be alternately layered with a separator 20 interposed therebetween. . In the following description, the “stacking direction” means the stacking direction of the positive electrode sheet 18 and the negative electrode sheet 19 in the electrode assembly 12.

  The positive electrode sheet 18 includes a positive electrode metal foil 21 and a positive electrode active material layer 22 formed by applying and drying an active material mixture containing a positive electrode active material on both surfaces thereof. The positive electrode metal foil 21 of this embodiment is a metal foil formed from aluminum or an aluminum alloy. A portion of the positive electrode metal foil 21 where the positive electrode active material layer 22 is not formed constitutes a non-coated portion 23 as a metal exposed portion where the positive electrode metal foil 21 is exposed. Further, a positive electrode current collecting tab 24 protrudes from the edge portion 18 a of the positive electrode sheet 18. The positive electrode current collecting tab 24 is a part of the positive electrode metal foil 21 constituting the non-coated portion 23.

  Moreover, the negative electrode sheet 19 has the negative electrode metal foil 25, and the negative electrode active material layer 26 formed by apply | coating the active material mixture containing a negative electrode active material to both surfaces, and making it dry. The negative electrode metal foil 25 of the present embodiment is a metal foil formed from copper. The portion of the negative electrode metal foil 25 where the negative electrode active material layer 26 is not formed constitutes an uncoated portion 27 where the negative electrode metal foil 25 is exposed. A negative electrode current collecting tab 28 protrudes from the edge 19 a of the negative electrode sheet 19. The negative electrode current collecting tab 28 is a part of the negative electrode metal foil 25 constituting the non-coated portion 27.

  As shown in FIG. 1, a positive electrode current collecting tab group 24 a as a metal exposed portion group in which a plurality of positive electrode current collecting tabs 24 are layered is projected from the edge 12 a of the electrode assembly 12. The positive electrode current collecting tab group 24a is joined and electrically connected to one end of a rectangular plate-like positive electrode conductive member 30 extending along the protruding direction of the positive electrode current collecting tab group 24a by resistance welding. The positive electrode conductive member 30 is made of aluminum or an aluminum alloy.

  Here, in resistance welding, as shown in FIG. 3, the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30 are paired with a pair of electrodes for resistance welding (hereinafter referred to as “welding electrodes”) 32 from the stacking direction. In this welding method, the energized portion is heated by energizing between the welding electrodes 32 while being pressed while being held, and the positive electrode current collecting tab 24 and the positive electrode conductive member 30 are melted and joined. In FIG. 3, six positive current collecting tabs 24 are shown for convenience of explanation, but in reality, a larger number of positive current collecting tabs 24 are layered.

  As shown in FIG. 1, the other end of the positive electrode conductive member 30 is electrically connected to the positive electrode terminal 15, and the positive electrode conductive member 30 is fixed to the case 11 (lid member 11b). In the present embodiment, the positive electrode terminal 15 and the positive electrode conductive member 30 constitute an electrode terminal.

  In addition, a negative electrode current collecting tab group 28a in which a plurality of negative electrode current collecting tabs 28 are stacked in a layered manner at a portion different from the positive electrode current collecting tab group 24a is protruded from the edge 12a of the electrode assembly 12. The negative electrode current collecting tab group 28a is joined and electrically connected to one end of a rectangular plate-like negative electrode conductive member 31 extending along the protruding direction of the negative electrode current collecting tab group 28a by resistance welding. The other end of the negative electrode conductive member 31 is electrically connected to the negative electrode terminal 16 and is fixed to the case 11 (lid member 11b).

Next, the welding (joining) structure between the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 will be described in more detail with reference to FIGS.
As shown in FIGS. 1 and 3, when viewed from the stacking direction, one end side of the positive electrode conductive member 30 and the positive electrode current collecting tab group 24 a overlap each other, and the positive electrode current collecting tab group 24 a and the positive electrode conductive member are overlapped. A contact portion 33 is provided at a portion overlapping with 30 to be a trace of contact with the welding electrode 32 when resistance welding is performed. In this embodiment, since the round bar-shaped welding electrode 32 is used, the contact portion 33 is a circular recess as viewed from the stacking direction. In the contact portion 33, the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 are not welded.

  Further, when viewed from the stacking direction, in the portion where the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 are overlapped, the positive electrode current collecting tab group 24a and the positive electrode are closer to the lid member 11b (positive electrode terminal 15) side than the contact portion 33. A hole 34 is formed as a hole formed by pressing with a cylindrical jig Z having a sharp tip from the positive electrode current collecting tab group 24a side in a state where the conductive member 30 is overlaid.

  The inner peripheral surface of the hole 34 and a portion adjacent to the inner peripheral surface are each pressed by the jig Z and pressed into a columnar shape by the positive electrode current collecting tabs 24. And the positive electrode conductive member 30 becomes a pressure contact portion 35 that is pressure-contacted (contacted) with each other in the stacking direction (colored in black in the drawing). As described above, the pressure contact portion 35 is provided at a position where the entire portion does not overlap the contact portion 33.

  A portion of the press-contact portion 35 along the inner peripheral surface of the hole 34 is provided with a welded portion 36 in which the positive electrode current collecting tabs 24 and the positive electrode conductive member 30 are welded and integrated with each other. . The weld 36 extends over the entire inner peripheral surface of the hole 34 to one surface located at both ends of the positive electrode current collecting tab group 24 a in the stacking direction and the other surface facing the positive electrode conductive member 30.

  Therefore, the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 are joined and electrically connected to each other by the welded portion 36 provided along the inner peripheral surface of the hole portion 34 in the press contact portion 35. Yes. As described above, the pressure contact portion 35 is welded to the positive electrode conductive member 30 at a portion that does not overlap the contact portion 33.

  As shown in FIG. 1, when viewed from the stacking direction, one end side of the negative electrode conductive member 31 and the negative electrode current collecting tab group 28a are overlapped, and the negative electrode current collecting tab group 28a and the negative electrode conductive member 31 are The overlapping portion is provided with a contact portion 33 that becomes a trace of contact with the welding electrode 32 when resistance welding is performed. In addition, in the contact part 33 in the negative electrode current collection tab group 28a, each negative electrode current collection tab group 28a and the negative electrode electrically-conductive member 31 are welded in the lamination direction, and are electrically connected.

Next, the operation of the secondary battery 10 configured as described above will be described.
In general, an oxide film (passive film) is formed on the surface of each positive electrode current collecting tab 24 constituting the positive electrode current collecting tab group 24a, and individual positive electrode current collecting tabs 24 are slightly bent. As a result, the electrical resistance of the positive electrode current collecting tab group 24a in the stacking direction becomes relatively high. On the other hand, the electrical resistance in the stacking direction is reduced in the press contact portions 35 where the positive electrode current collecting tabs 24 and the positive electrode conductive members 30 are press contacted (contacted) with each other as compared with portions other than the press contact portions 35.

  For this reason, even if the current supplied from the welding electrode 32 that is in contact with the contact portion 33 is separated from the contact portion 33, the current flows preferentially through the pressure contact portion 35. As a result, resistance welding is performed at the press contact portion 35 to provide a weld portion 36.

  In the present embodiment, since the hole 34 is provided by being pushed out by the cylindrical jig Z, the closer to the hole 34 in the press contact part 35, the more the positive electrode current collecting tab 24 and the positive electrode conductive member are. 30 are strongly pressed and electric resistance is low. In particular, on the inner peripheral surface of the hole 34, the positive electrode metal foils 21 are joined (contacted) with each other without intervening the oxide film, whereby the electrical resistance is further reduced. For this reason, in the present embodiment, the welded portion 36 is provided along the inner peripheral surface of the hole portion 34.

  In the present embodiment, the electrical resistance between the welding electrodes 32 can be adjusted by adjusting the distance between the contact portion 33 and the pressure contact portion 35. In other words, the electrical resistance between the welding electrodes 32 can be lowered by providing the contact portion 33 and the press contact portion 35 close to each other, and can be increased by providing the contact portion 33 and the press contact portion 35 apart from each other. Therefore, the size (welding strength) of the welded portion 36 can be easily adjusted by adjusting the separation distance between the contact portion 33 and the pressure contact portion 35.

  The press contact portion 35 is provided at a position where the entire press contact portion 35 does not overlap the contact portion 33. Therefore, the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 can be welded by resistance welding even at a position completely separated from the contact portion 33.

Next, a method for manufacturing the secondary battery 10 will be described focusing on a method for welding the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30.
First, the positive electrode sheet 18 and the negative electrode sheet 19 are alternately laminated with the separator 20 interposed therebetween, and the electrode assembly 12 in which the positive electrode current collecting tab group 24a and the negative electrode current collecting tab group 28a protrude from the edge 12a. Form.

  Next, as shown in FIG. 3, the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30 are overlapped in the stacking direction. Then, at the position separated from the contact portion 33 that contacts the welding electrode 32 toward the lid member 11b, the tip of the jig Z is pressed from the positive electrode current collecting tab group 24a side, thereby forming the hole 34 and the positive electrode collector. The electric tab 24 and the positive electrode conductive member 30 are pressed against each other to provide a pressure contact portion 35 (pressure contact process). At this time, the oxide film covering the surface of each positive electrode current collecting tab 24 was broken by the jig Z at the portion along the inner peripheral surface of the hole 34 in the press contact portion 35, and the new surfaces were joined to each other. It becomes a state. That is, the pressure contact process can be grasped as a contact process in which the positive electrode current collecting tabs 24 are brought into contact with each other on the new surfaces without interposing an oxide film.

  Then, in the contact portion 33, the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30 are brought into contact with the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30 from the stacking direction. The member 30 is welded (welding process). At this time, the current supplied from the welding electrode 32 does not flow linearly in the stacking direction in the positive electrode current collecting tab group 24a between the welding electrodes 32, but flows around the pressure contact portion 35 having a lower electrical resistance. .

  For this reason, in this embodiment, the welding part 36 is provided along the inner peripheral surface of the hole 34 by the pressure contact part 35 generating heat and melting, and the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 are electrically connected. Connected. Therefore, by bringing the welding electrode 32 into contact with the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 at a position apart from the lid member 11b, the operation of bringing the welding electrode 32 into contact can be facilitated, and the lid member 11b. The positive electrode current collecting tab group 24a and the positive electrode conductive member 30 can be welded at a position close to the side.

  The negative electrode current collecting tab group 28a and the negative electrode conductive member 31 are not provided with the press contact portion 35 (hole portion 34) in the negative electrode current collecting tab group 28a. Welds extending so as to be linearly connected to each other are formed and welded to each other.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The positive electrode current collecting tab group 24 a is provided with a press contact portion 35 at a position not overlapping the contact portion 33, and the press contact portion is a positive electrode in a portion of the press contact portion 35 that does not overlap the contact portion 33. The conductive member 30 is welded. In the press contact portion 35 where each positive electrode current collecting tab 24 is press-contacted, since the electric resistance is lower than the portion other than the press contact portion 35, the current supplied from the welding electrode 32 in contact with the contact portion 33 is As a result, resistance welding is performed in the pressure contact portion 35. Therefore, the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 (positive electrode terminal 15) can be resistance-welded and electrically connected at a position away from the contact portion 33.

  (2) For this reason, since the contact part 33 and the welding part 36 (press-contact part 35) can be set in a different part, while suppressing workability fall, the positive electrode current collection tab group 24a, the positive electrode electrically-conductive member 30, and Can be resistance welded at a desired portion.

(3) By adjusting the separation distance between the contact portion 33 and the pressure contact portion 35, the size of the welded portion 36, that is, the welding strength can be easily adjusted.
(4) The press contact portion 35 is provided at a position where the entire press contact portion 35 does not overlap the contact portion 33. For this reason, even if it is the position away from the contact part 33, the positive electrode current collection tab group 24a and the positive electrode electrically-conductive member 30 can be welded by resistance welding.

(5) In the secondary battery 10, the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30 (positive electrode terminal 15) can be welded at a position away from the contact portion 33 with which the welding electrode 32 is brought into contact.
(6) In a state where the positive electrode current collecting tabs 24 are brought into contact with each other, and the welding electrode 32 is brought into contact with a contact portion 33 which is a portion separated from a place where the positive electrode current collecting tabs 24 are in contact with each other (pressure contact portion 35). Energization is performed, and the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 are welded. The electrical current supplied from the welding electrode 32 is in contact with the positive current collecting tabs 24 because the electrical resistance is lower at the locations where the positive current collecting tabs 24 are in contact with each other. As a result, resistance welding is performed at a location where the positive electrode current collecting tabs 24 are in contact with each other. Therefore, the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 can be resistance-welded and electrically connected at a position away from the contact portion 33.

  (7) Even if the contact portion 33 is set at a position separated from the lid member 11b, resistance welding can be performed by the press contact portion 35 provided at a position close to the lid member 11b. That is, in the welding process, the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 can be welded at a desired portion while suppressing a decrease in resistance welding workability.

The embodiment is not limited to the above, and may be embodied as follows, for example.
○ The hole 34 may be formed by punching. In this case, since the hole 34 is provided through the positive electrode current collecting tab group 24 a and the positive electrode conductive member 30, the positive electrode current collecting tab 24 and the positive electrode conductive member are arranged along the inner peripheral surface of the hole 34. 30 is reliably pressure-contacted (contacted), electric resistance is reduced, and it can weld easily.

  As shown in FIG. 4, the press contact portion 35 may be provided along a cut portion 40 extending from the edge portion of the positive electrode current collecting tab group 24 a toward the contact portion 33. In this case, in a state where the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 are overlapped, the cut portion 40 is formed by pressing the positive current collector tab group 24a with a cutter from the side of the positive current collector tab group 24a. Along each cut surface, it is possible to provide a pressure contact portion 35 in which each positive electrode current collecting tab 24 and the positive electrode conductive member 30 are pressed (contacted) in the stacking direction. Even if comprised in this way, the welding part 36 to which each positive electrode current collection tab 24 and the positive electrode electrically-conductive member 30 were mutually welded is provided in the part along the cut surface of the notch part 40 among the press-contact parts 35. Can do. According to this, while being able to provide the press-contact part 35 simply with respect to the positive electrode current collection tab group 24a, adjusting the notch distance from an edge part, the electrical resistance at the time of performing resistance welding, ie, welding You can adjust the strength.

  As shown in FIG. 4, the pressure contact portion 35 may partially overlap the contact portion 33. That is, the press contact portion 35 may be welded to the positive electrode terminal 15 at least in a portion of the press contact portion 35 that does not overlap the contact portion 33.

  ○ As shown in FIG. 5, for example, by pressing a sharp jig, the positive electrode current collecting tabs 24 and the positive electrode conductive members 30 are pressed (contacted) in the stacking direction without providing the holes 34 and the notches 40, A pressure contact portion 35 may be provided.

  (Circle) the press-contact part 35 may be provided along the edge of the positive electrode current collection tab group 24a. In this case, the press contact portion 35 can be provided along the cut surface by pressing the edge of the positive electrode current collecting tab group 24a with a cutter or the like.

The press contact portion 35 may be formed by penetrating the positive electrode current collecting tab group 24a with a needle-like jig.
In the press contact portion 35, it is sufficient that at least the positive electrode current collecting tabs 24 are pressed (contacted) with each other, and the positive electrode current collecting tab group 24a and the positive electrode conductive member 30 do not have to be pressed.

(Circle) each positive electrode current collection tab 24 and the positive electrode electrically-conductive member 30 may be welded in the whole press-contact part 35. FIG.
A pressure welding portion 35 may be provided on the negative electrode current collecting tab group 28a, and resistance welding may be performed by bringing the welding electrode 32 into contact with the contact portion 33 that does not at least partially overlap the pressure welding portion 35.

The welding electrode 32 may be changed to a different shape such as a prismatic shape.
The belt-like electrode may be sufficient as the positive electrode sheet 18 and the negative electrode sheet 19. In this case, the electrode assembly 12 may be a wound electrode assembly in which the positive electrode sheet 18 and the negative electrode sheet 19 are wound with a band-shaped separator 20 interposed therebetween.

The positive electrode sheet 18 and the negative electrode sheet 19 may be formed by applying an active material mixture on one side.
O You may actualize in secondary batteries, such as a nickel-hydrogen secondary battery, and electrical storage apparatuses, such as a lithium ion capacitor.

  O You may actualize in the electrical storage apparatus used other than a vehicle.

  DESCRIPTION OF SYMBOLS 10 ... Lithium ion secondary battery (secondary battery, electrical storage apparatus), 11 ... Case, 12 ... Electrode assembly, 15 ... Positive electrode terminal (electrode terminal), 18 ... Positive electrode sheet (electrode), 20 ... Separator, 21 ... Positive electrode Metal foil (metal foil), 22 ... positive electrode active material layer (active material layer), 23 ... non-coated part (metal exposed part), 24 ... positive electrode current collecting tab (metal exposed part), 24a ... positive electrode current collecting tab group (Metal exposed part group), 30 ... positive electrode conductive member (electrode terminal), 32 ... welding electrode (electrode for resistance welding), 33 ... contact part, 35 ... pressure contact part, 40 ... notch part.

Claims (6)

An electrode assembly comprising an electrode having an active material layer formed on the surface of a metal foil, and a separator for insulating between the electrodes, wherein the electrode overlaps in layers with the separator interposed therebetween, and the electrode assembly And a case where the electrode terminal is fixed, and a power storage device comprising:
The electrode assembly has a metal exposed portion group in which the metal exposed portions where the metal foil of the electrode is exposed overlap in layers,
The metal exposed portion group is provided with a contact portion to which an electrode for resistance welding is contacted and a pressure contact portion in which the metal exposed portions constituting the metal exposed portion group are pressed against each other,
The pressure contact portion is provided at a position where at least a part of the pressure contact portion does not overlap the contact portion, and is welded to the electrode terminal at a portion of the pressure contact portion that does not overlap at least the contact portion. A power storage device characterized by the above.   The power storage device according to claim 1, wherein the press contact portion is provided along an inner peripheral surface of the hole.   The power storage device according to claim 1, wherein the press-contact portion is provided along a cut portion extending from an edge portion of the metal exposed portion group toward the contact portion.   The power storage device according to claim 1, wherein the press contact portion is provided at a position where the entire press contact portion does not overlap the contact portion.   The power storage device according to claim 1, wherein the power storage device is a secondary battery. An electrode assembly comprising an electrode having an active material layer formed on the surface of a metal foil, and a separator for insulating between the electrodes, wherein the electrode overlaps in layers with the separator interposed therebetween, and the electrode assembly And a case where the electrode terminal is fixed, and the electrode assembly is a method of manufacturing a power storage device having a metal exposed portion group in which metal exposed portions where the metal foil of the electrode is exposed overlap in layers. There,
A contact step of contacting the metal exposed portions constituting the metal exposed portion group;
Energization is performed in a state where an electrode for resistance welding is in contact with a contact portion that is a position where at least a part of the portion where the metal exposed portions are in contact with each other, and at least of the portions where the metal exposed portions are in contact with each other And a welding step of welding to the electrode terminal at a portion that does not overlap with the contact portion.