JP2016091661A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device which is capable of reducing load generated in a current collecting part group of an electrode assembly.SOLUTION: There is provided a power storage device comprising: an electrode assembly 12 where a positive electrode 16 and a negative electrode 17 overlaps in layers in a mutually insulated manner; a case 11 housing the electrode assembly 12; an electrode terminal 29 which projects to the outside of the case 11; and a conductive path EL between the electrode assembly 12 and the electrode terminal 29. The electrode assembly 12 comprises a positive electrode collecting part group 25 where a positive electrode collecting part 21 overlaps in layers and at least a part of the conductive path EL are composed of a single wire part 31 as a metal single wire and the single wire part 31 is joined to the positive electrode collecting part group 25.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power storage device.

  Conventionally, vehicles such as EVs (Electric Vehicles) and PHVs (Plug in Hybrid Vehicles) have been mounted with lithium-ion secondary batteries or nickel-hydrogen secondary batteries as power storage devices that store power supplied to electric motors and the like. . Such a power storage device includes an electrode assembly in which electrodes are stacked in layers, a case housing the electrode assembly, and an electrode terminal protruding outside the case, and the electrode assembly and the electrode terminal And are electrically connected.

  For example, in the power storage device of Patent Document 1, a lead is provided and the leading end portion of the lead protrudes to the outside of the case, while the base end portion of the lead is joined to the current collecting portion group of the electrode assembly. The tip of each of them functions as an electrode terminal.

JP 2001-338688 A

  However, the lead of Patent Document 1 is a square plate-like conductive member made of metal and has high rigidity. For this reason, in Patent Document 1, for example, a load is applied to the joint portion between the conductive member and the current collecting unit group due to vibration applied from the outside of the power storage device or expansion or contraction of the electrode assembly accompanying charging / discharging of the power storage device. Is likely to occur.

  The present invention has been made paying attention to the problems existing in the above-described conventional technology, and an object of the present invention is to provide a power storage device capable of reducing a load generated in a current collecting unit group of an electrode assembly.

  A power storage device that solves the above problem is a layered structure in which electrodes having a metal foil, an active material layer that covers at least a part of the metal foil, and a metal foil-shaped current collector are insulated from each other. An electrode assembly that overlaps, a case that houses the electrode assembly, an electrode terminal that protrudes outside the case, and a conductive path between the electrode assembly and the electrode terminal. The electrode assembly has a current collecting part group in which the foil-like current collecting parts are layered, and at least a part of the conductive path is composed of a single wire part that is a single metal wire. The gist is that the single wire portion is joined to the current collecting portion group.

  According to this, at least a part of the conductive path between the electrode assembly and the electrode terminal is composed of a single wire portion that is a single wire made of metal, and this single wire portion is a current collecting portion group of the electrode assembly. It is joined to. Therefore, for example, even if the electrode assembly is displaced or deformed due to vibration applied from the outside of the power storage device or expansion or contraction of the electrode assembly due to charging / discharging of the power storage device, The single wire portion can be deformed by following the displacement and deformation. That is, the load generated at the junction between the single wire portion and the current collecting portion group is absorbed by the single wire portion constituting the conductive path. Therefore, it is possible to reduce the load generated in the current collecting unit group of the electrode assembly.

  About the said electrical storage apparatus, it is preferable that the said single wire part has a round terminal in the front-end | tip part, and the said round terminal is joined to the said current collection part group. According to this, since the round terminal is joined to the current collecting part group, it is possible to prevent the current collecting part group from being damaged when the round terminal contacts the current collecting part group.

In the power storage device, it is preferable that the round terminal and the current collecting unit group are joined by a split pin or a rivet. According to this, a single wire part and a current collection part group can be joined simply.
About the said electrical storage apparatus, it is preferable that the said round terminal is crimped | bonded to the front-end | tip part of the said single wire part. According to this, a round terminal can be simply provided with respect to a single wire part.

  Regarding the power storage device, the power storage device is preferably a secondary battery. According to this, as the secondary battery, the load generated in the current collecting part group of the electrode assembly can be reduced, and as a result, the durability as the secondary battery can be improved.

  According to the present invention, it is possible to reduce the load generated in the current collecting unit group of the electrode assembly.

(A) is sectional drawing which shows a secondary battery typically, (b) is the elements on larger scale of (a). (A) is the 1-1 sectional view taken on the line of FIG. 1, (b) is the elements on larger scale of (a). The perspective view which shows an electrode assembly typically. (A) And (b) is a schematic diagram which shows the joining method of a round terminal and a current collection part group. (A) And (b) is a schematic diagram which shows the joining method of the round terminal and current collection part group in another embodiment.

Hereinafter, an embodiment of the secondary battery will be described.
As shown in FIGS. 1A and 1B and FIGS. 2A and 2B, in the present embodiment, the secondary battery 10 as a power storage device is a lithium ion secondary battery, and This is a prismatic battery having a square appearance. The secondary battery 10 includes a case 11 and an electrode assembly 12 accommodated in the case 11. In FIG. 1 and FIG. 2, the electrode assembly 12 is separated from the inner wall surface of the case 11 for convenience of explanation, but in actuality, it is in contact with or close to the case 11.

  The case 11 includes a bottomed square cylindrical case body 13 having an opening 14 and a square plate-like lid 15 that closes the opening 14. The case main body 13 and the lid 15 are made of metal such as stainless steel or aluminum. The case 11 contains an electrolytic solution as an electrolyte (not shown).

  As shown in FIG. 3, the electrode assembly 12 includes a positive electrode 16 as a belt-like electrode, a negative electrode 17 as a belt-like electrode, and a belt-like separator that insulates between the electrodes 16 and 17. 18. The electrode assembly 12 is wound in layers with the electrodes 16 and 17 insulated from each other by winding the positive electrode 16 and the negative electrode 17 with the separator 18 interposed therebetween. This is a rotary electrode assembly.

  The positive electrode 16 includes a positive metal foil 19 as a strip-shaped metal foil, and a positive electrode active material layer 20 as an active material layer covering the positive metal foil 19. The positive electrode metal foil 19 is made of, for example, aluminum. The positive electrode active material layer 20 is provided by applying a positive electrode active material on both surfaces of the positive electrode metal foil 19. Further, the positive electrode 16 is a positive electrode current collector as a foil-like current collector that is an uncoated portion where the positive electrode active material is not applied along the edge 16a extending along the length direction D1 of the positive electrode 16. It has an electric part 21.

  The negative electrode 17 includes a negative electrode metal foil 22 as a strip-shaped metal foil and a negative electrode active material layer 23 as an active material layer covering the negative electrode metal foil 22. The negative electrode metal foil 22 is made of, for example, copper. The negative electrode active material layer 23 is provided by applying a negative electrode active material on both surfaces of the negative electrode metal foil 22. The negative electrode 17 is a negative current collector as a foil-shaped current collector that is an uncoated portion to which the negative electrode active material is not applied along the edge 17a extending along the length direction D1 of the negative electrode 17. An electric part 24 is provided.

  The electrode assembly 12 includes a positive electrode current collector portion group 25 in which the positive electrode current collector portions 21 are stacked in layers at the first end portion 12a of both ends in the width direction D2 of the electrodes 16 and 17. The electrode assembly 12 includes a negative electrode current collector part group in which the negative electrode current collector part 24 is layered on the second end part 12b opposite to the first end part 12a among the both end parts in the width direction D2. 26. Each of the current collecting unit groups 25 and 26 includes the electrodes 16 and 17 in a state where the positive electrode current collecting unit 21 is disposed on the first end 12a side and the negative electrode current collecting unit 24 is disposed on the second end 12b side. It is provided by winding. In the following description, the direction in which the current collecting portions overlap in each current collecting portion group 25, 26 is simply referred to as a stacking direction D3.

  Further, as shown in FIGS. 1A and 1B and FIGS. 2A and 2B, the secondary battery 10 is electrically connected to the electrode assembly 12 accommodated in the case 11. As electrode terminals for giving and receiving, a positive electrode terminal 29 and a negative electrode terminal 29 are provided. Each electrode terminal 29 has a first end protruding outside the case 11, while a second end opposite to the first end protrudes inside the case 11 with respect to the lid 15. Is fixed.

  Further, the secondary battery 10 includes a positive electrode connection member 30 that electrically connects the positive electrode current collector portion 25 and the positive electrode terminal 29. Further, the secondary battery 10 includes a negative electrode connecting member 30 that electrically connects the negative electrode current collecting portion group 26 and the negative electrode terminal 29.

  Each connection member 30 constitutes a conductive path EL between the positive electrode current collector part group 25 and the electrode terminal 29 for positive electrode, and between the negative electrode current collector part group 26 and the electrode terminal 29 for negative electrode. . Since the connection member 30 of the present embodiment has the same configuration for the positive electrode and the negative electrode, in the following description, the connection member 30 for the positive electrode will be described in detail, and the description of the connection member 30 for the negative electrode will be simplified. To do.

  The positive electrode connecting member 30 has a single wire portion 31 that is a single wire made of metal. The single wire portion 31 is a so-called round single wire and is different from a stranded wire obtained by combining a plurality of metal wires. The cross-sectional shape of the single wire portion 31 is a circle (perfect circle) having a constant diameter. The single wire part 31 has elasticity. Of both ends of the single wire portion 31, the base end portion 31 a is joined to the second end portion of the electrode terminal 29 for positive electrode.

  In addition, the positive electrode connecting member 30 includes a metal round terminal 32 that is connected to the distal end portion 31 b of the single wire portion 31. The positive electrode round terminal 32 is an annular plate-like member having a circular through hole 32a penetrating in the thickness direction. The round terminal 32 is crimped to the distal end portion 31 b of the single wire portion 31. The single wire portion 31 and the round terminal 32 for the positive electrode are made of, for example, aluminum. Moreover, the single wire part 31 and the round terminal 32 for negative electrodes are copper, for example.

  The secondary battery 10 has a split pin 33 that joins the positive electrode current collector group 25 and the positive electrode round terminal 32. The split pin 33 has a flange-shaped head portion 33a and a plurality of (two in this embodiment) leg portions 33b protruding from the head portion 33a along the stacking direction D3. Each leg portion 33 b of the split pin 33 is bent so that the tip end portion thereof is along the surface direction of the round terminal 32 in a state of passing through the positive electrode current collector portion group 25 and being inserted into the through hole 32 a of the round terminal 32. It has been. Thereby, the positive electrode current collecting part group 25 and the round terminal 32 are sandwiched between the head part 33a of the split pin 33 and the tip part of the leg part 33b, and are in close contact with each other.

Next, the operation of the secondary battery 10 configured as described above will be described.
For example, when the electrode assembly 12 swings in the case 11 due to vibration applied from the outside of the secondary battery 10, the elastic single wire portion 31 is deformed following the electrode assembly 12. . Further, for example, when the electrode assembly 12 expands and contracts as the secondary battery 10 is charged / discharged, the elastic single wire portion 31 is deformed following the electrode assembly 12. For this reason, compared with the structure which joined the positive electrode current collection part group 25 and the highly rigid connection member, a load (stress) will concentrate on the junction part of the positive electrode current collection part group 25 and the connection member 30. FIG. Can be suppressed.

  In addition, since the round terminal 32 is joined to the current collecting unit groups 25 and 26, for example, a terminal having a shape different from a circle such as a square plate shape is joined to the current collecting unit groups 25 and 26. Moreover, it can suppress that a current collection part will be damaged in a contact part with the current collection part which comprises a current collection part group.

  Further, as shown in FIGS. 4A and 4B, the connection member 30 and the current collecting unit groups 25 and 26 can be simply joined by using the split pin 33. Here, in the unused split pin 33, each leg 33b is not bent and is in a straight state. First, the leg portion 33b of the unused split pin 33 is in a state of passing through the positive electrode current collector portion group 25 and is inserted into the through hole 32a of the round terminal 32. Subsequently, the tip end portion of each leg portion 33 b is bent along the surface direction of the round terminal 32. At this time, any one of the current collecting unit groups 25 and 26 and the round terminal 32 are sandwiched between the head portion 33a of the split pin 33 and the tip portion of the leg portion 33b, and are brought into close contact with each other.

Therefore, according to the above embodiment, the following effects can be obtained.
(1) For example, vibrations applied from the outside of the secondary battery 10 and loads caused by expansion and contraction of the electrode assembly 12 accompanying charging / discharging of the secondary battery 10 are absorbed by the single wire portion 31 constituting the conductive path EL. Is done. Accordingly, it is possible to reduce the load generated in the current collecting unit groups 25 and 26 of the electrode assembly 12.

  (2) Since the round terminal 32 is joined to the current collecting unit groups 25 and 26, the current collecting unit groups 25 and 26 are damaged when the round terminal 32 contacts the current collecting unit groups 25 and 26. Can be suppressed.

(3) Since the round terminal 32 and each current collection part group 25 and 26 are joined by the split pin 33, the single wire part 31 and each current collection part group 25 and 26 can be joined simply.
(4) The round terminal 32 can be simply provided to the single wire portion 31 by crimping.

(5) The load generated in the current collecting unit groups 25 and 26 of the electrode assembly 12 as the secondary battery 10 can be reduced, and as a result, the durability as the secondary battery 10 can be improved.
(6) Since the single wire portion 31 is a single wire, the electrical resistance at the joint portion with the round terminal 32 can be lowered.

In addition, you may change the said embodiment as follows.
As shown in FIGS. 5A and 5B, the round terminal 32 and the positive electrode current collector group 25 may be joined with a rivet 35. The unused rivet 35 includes a flange-shaped head portion 35a and a rod-shaped body portion 35b protruding from the head portion 35a along the stacking direction D3. Then, the body portion 35 b of the rivet 35 is in a state of being penetrated through the positive electrode current collector portion group 25 and is in a state of being inserted through the through hole 32 a of the round terminal 32. Subsequently, the distal end portion of the body portion 35b is deformed to provide a flange-shaped deformed portion 35c. At this time, the positive electrode current collector part 25 and the round terminal 32 are preferably sandwiched between the head part 35a and the deforming part 35c of the rivet 35 and are brought into close contact with each other. This example can be similarly applied to the negative electrode.

  O The cross-sectional shape of the single wire part 31 may be an ellipse. In addition, the single wire part 31 is good in the ratio of the 1st diameter and the 2nd diameter in the direction orthogonal to this 1st diameter being the range of 1: 1 to 1: 3, for example.

The round terminal 32 may be crimped to the tip portion 31b of the single wire portion 31. The round terminal 32 may be formed integrally with the distal end portion 31 b of the single wire portion 31.
The round terminal 32 may be a U-shape having a notch communicating with the through hole 32a. That is, the round terminal 32 may not be annular.

A square plate-like terminal may be connected to the tip 31b of the single wire part 31 instead of the round terminal 32.
The round terminal 32 and the current collecting unit groups 25 and 26 may be joined by resistance welding or laser welding.

○ The round terminal 32 may be omitted. In this case, the single wire portion 31 may be welded to the current collecting portion groups 25 and 26.
The conductive path EL may be configured to further include one or a plurality of conductive members in addition to the single wire portion 31 and the round terminal 32.

The positive electrode active material layer 20 may be provided only on one side of the positive electrode metal foil 19. The negative electrode active material layer 23 may be provided only on one side of the negative electrode metal foil 22.
The positive electrode current collector 21 may be provided by bonding a metal foil separate from the positive electrode metal foil 19 to the edge. The negative electrode current collector 24 can be similarly changed.

The electrode assembly 12 may be a stacked electrode assembly in which a sheet-like positive electrode 16 and a sheet-like negative electrode 17 are laminated with a separator 18 interposed therebetween.
Each of the current collecting unit groups 25 and 26 may be provided at one end of the electrode assembly 12.

  The number of members constituting the case 11 may be three or more, and the shape of each member may be changed. For example, the case 11 may be formed by combining a first member having an opening and a second member having an opening so that the openings face each other.

  The shape of the case 11 may be changed as appropriate in accordance with the shape of the electrode assembly 12 to be accommodated. For example, the case 11 may be cylindrical. In this case, a bottomed cylindrical case body 13 and a disk-shaped lid 15 may be used.

(Circle) the secondary battery 10 may be mounted in the passenger car and industrial vehicle as a vehicle, and may be applied as a stationary electrical storage apparatus.
The secondary battery 10 is not limited to a lithium ion secondary battery, and may be another secondary battery such as a nickel hydrogen secondary battery or a nickel cadmium secondary battery.

  O Not only a secondary battery, but may be embodied as a capacitor such as an electric double layer capacitor or a lithium ion capacitor.

  EL ... conductive path, 10 ... secondary battery (power storage device), 11 ... case, 12 ... electrode assembly, 16 ... positive electrode (electrode), 17 ... negative electrode (electrode), 19 ... positive electrode metal foil (metal foil) , 20 ... positive electrode active material layer (active material layer), 21 ... positive electrode current collector (foil-shaped current collector), 22 ... negative electrode metal foil (metal foil), 23 ... negative electrode active material layer (active material layer), 24 ... Negative electrode current collector (foil-shaped current collector), 25... Positive electrode current collector (group of current collectors), 26... Negative electrode current collector (group of current collectors), 29. 31 ... Single wire part, 31a ... Tip part, 32 ... Round terminal, 33 ... Split pin, 35 ... Rivet.

Claims (5)

An electrode assembly in which electrodes having a metal foil, an active material layer covering at least a part of the metal foil, and a metal foil-shaped current collector are layered in an insulated state;
A case housing the electrode assembly;
An electrode terminal protruding outside the case;
A conductive path between the electrode assembly and the electrode terminal,
The electrode assembly has a current collecting part group in which the foil-like current collecting parts are layered,
At least a part of the conductive path is composed of a single wire portion that is a single wire made of metal, and the single wire portion is joined to the current collector portion group.   The power storage device according to claim 1, wherein the single wire portion has a round terminal at a tip end portion, and the round terminal is joined to the current collector portion group.   The power storage device according to claim 2, wherein the round terminal and the current collecting unit group are joined by a split pin or a rivet.   The power storage device according to claim 2 or 3, wherein the round terminal is pressure-bonded to a distal end portion of the single wire portion.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.