JP2017022060A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device that is able to shorten time required to join a tab to the electrodes (cathode, anode) of a lamination type electrode assembly.SOLUTION: A power storage device comprises a lamination type electrode assembly in which a plurality of cathodes and a plurality of anodes are alternately arranged in layers while an insulating state is maintained. A cathode comprises a cathode body 23 and a belt-like cathode tab 24 pulled out from the cathode body 23. The anode comprises an anode body 27 and a belt-like anode tab 28 pulled out from the anode body 27. In the power storage device, the cathode tab 24 and anode tab 28 are conductive adhesive tapes, the cathode tab 24 is stuck to the cathode body 23 and the anode tab 28 is stuck to the anode body 27.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a power storage device, and more particularly, to a power storage device including a stacked electrode assembly.

  In recent years, lithium ion secondary batteries have been adopted not only as power sources for electronic devices but also as power sources for hybrid vehicles and electric vehicles. Usually, a battery case of a lithium ion secondary battery contains an electrode assembly as a power generation element. The electrode assembly includes a positive electrode obtained by applying a positive electrode active material to a metal foil, and a negative electrode active material on the metal foil. It has a coated negative electrode and a separator interposed between the positive electrode and the negative electrode. As an electrode assembly, for example, there are a wound electrode assembly and a stacked electrode assembly. The wound electrode body is formed by winding an electrode sheet with a separator interposed between a long positive electrode and a negative electrode. On the other hand, a stacked electrode assembly has a structure in which a large number of positive electrodes, negative electrodes, and separators are alternately stacked.

  By the way, in the case of a laminated electrode assembly, a tab made of a metal foil is formed on a part of the edge of the electrode (positive electrode, negative electrode). The tab is a portion through which electricity flows during discharging or charging. The tab may be integrally formed by punching together with the metal foil of the electrode (positive electrode, negative electrode), or the same metal foil tab may be joined by welding to the edge of the metal foil of the electrode (positive electrode, negative electrode). is there. On the other hand, the lithium secondary battery disclosed in Patent Document 1 describes that a tab is joined to an electrode of a wound electrode assembly by welding or a conductive adhesive.

JP 2006-156365 A

  In the case of a stacked electrode body, it is necessary to provide a tab for each electrode (positive electrode, negative electrode). However, as in the case of the lithium secondary battery disclosed in Patent Document 1, when joining a tab to an electrode by welding, joining the tab to several tens of electrodes by welding is an extremely complicated operation. There is a problem of requiring a large amount of work time. Moreover, even when the tab is joined to a large number of electrodes with a conductive adhesive, a great amount of work time is required as in the case of welding.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electric storage capable of shortening the work time for joining a tab to an electrode (positive electrode, negative electrode) of a stacked electrode assembly. In providing equipment.

  In order to solve the above-described problems, the present invention includes a stacked electrode assembly in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked while maintaining an insulating state, and the positive electrode includes a positive electrode body and the positive electrode body A negative electrode tab, and the negative electrode in a power storage device including a negative electrode body and a belt-like negative electrode tab drawn from the negative electrode body, the positive electrode tab and the negative electrode tab are conductive adhesive tape, The positive electrode tab is attached to the positive electrode body, and the negative electrode tab is attached to the negative electrode body.

  In the present invention, the positive electrode tab and the negative electrode tab can be formed by bonding by sticking the ends of the conductive adhesive tape to the positive electrode main body and the negative electrode main body, respectively. Therefore, compared to the case of joining the positive electrode tab and the negative electrode tab by welding, it is easier to join, and the working time of joining can be shortened.

Further, in the above power storage device, a positive electrode aggregation portion that aggregates the plurality of positive electrode tabs in the stacking direction of the electrode assembly is formed, and a negative electrode aggregation portion that aggregates the plurality of negative electrode tabs in the stacking direction of the electrode assembly Is formed apart from the positive electrode aggregation portion, formed on the positive electrode aggregation portion by mutual adhesion of the plurality of positive electrode tabs, and formed on the negative electrode aggregation portion by mutual adhesion of the plurality of negative electrode tabs. It is good also as the structure currently made.
In this case, a positive electrode aggregation part can be formed by mutually sticking the edge part on the opposite side of the edge part of the electroconductive adhesive tape each affixed on the some positive electrode main body. Moreover, a negative electrode aggregation part can be formed by mutually sticking the edge part on the opposite side of the edge part of the electroconductive adhesive tape each affixed on the some negative electrode main body. A positive electrode aggregation part and a negative electrode aggregation part can be easily formed by mutually sticking a plurality of conductive adhesive tapes.

In the above power storage device, the positive electrode consolidating unit may have a structure in which a positive electrode conductive unit is bonded by bonding, and the negative electrode collecting unit may have a structure in which a negative electrode conductive unit is bonded by bonding.
In this case, the positive electrode conductive part can be joined to the positive electrode aggregated part by sticking the positive electrode conductive part to the adhesive surface of the conductive adhesive tape in the positive electrode aggregated part. Moreover, a negative electrode conductive part can be joined to a negative electrode aggregation part by sticking a negative electrode conductive part to the adhesive surface of the conductive adhesive tape in a negative electrode aggregation part.

Further, in the above power storage device, the positive electrode tab has a positive electrode tab bent portion formed by bending before mutual bonding, and the negative electrode tab is formed by bending before mutual bonding. It is good also as a structure which has.
In this case, as compared with the case where the positive electrode tabs are bent together after mutual bonding, the bending of the positive electrode tab can reduce the resistance to bending. Further, as compared with the case where the negative electrode tabs are bent together after being attached to each other, the bending of the negative electrode tab can reduce the resistance to bending.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage apparatus which can shorten the operation | work time which joins a tab to the electrode (a positive electrode, a negative electrode) of a laminated type electrode assembly can be provided.

1 is an exploded perspective view of a secondary battery according to an embodiment of the present invention. It is a longitudinal cross-sectional view of the secondary battery which concerns on this embodiment. It is a partial exploded perspective view of the electrode assembly with which the secondary battery concerning this embodiment is provided. (A)-(c) is a principal part side view explaining joining of a positive electrode tab (negative electrode tab). It is a perspective view explaining the manufacture process of the electrode assembly which concerns on this embodiment. It is a perspective view explaining the manufacture process of the electrode assembly with which the secondary battery which concerns on a modification is provided.

  Hereinafter, a power storage device according to an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a secondary battery as a power storage device is illustrated. Specifically, the secondary battery of the present embodiment is a lithium ion secondary battery.

  As shown in FIGS. 1 and 2, the secondary battery 10 of the present embodiment is a rectangular secondary battery. An electrode assembly 20 is accommodated in the battery case 11 of the secondary battery 10. The longitudinal direction of the battery case 11 shown in FIG. 1 is shown as the left-right direction, the height direction of the battery case 11 is shown as the up-down direction, and the short direction of the battery case 11 is shown as the front-back direction. The height direction of the battery case 11 coincides with the accommodation direction of the electrode assembly 20. The electrode assembly 20 is a power generation element that generates a battery function (such as charging / discharging).

  The battery case 11 has a bottomed cylindrical case body 12 and a rectangular flat lid 14 that closes the opening 13 of the case body 12. The case body 12 and the lid body 14 are made of a metal material (for example, aluminum). As shown in FIG. 2, an insulating sheet 15 is attached to the inner surface of the case body 12 as an insulating member for insulation from the electrode assembly 20 accommodated in the battery case 11. In addition, an insulating sheet 16 as an insulating member is attached to the inner side surface of the lid body 14 to insulate the electrode assembly 20 housed in the battery case 11. A pair of through holes 17 are formed in the lid body 14.

  As shown in FIG. 3, the electrode assembly 20 includes a sheet-like positive electrode 21 and a sheet-like negative electrode 22. The positive electrode 21 has a rectangular positive electrode main body 23 and a strip-shaped positive electrode tab 24 formed at the edge of the positive electrode main body 23. The positive electrode main body 23 has a rectangular positive electrode metal foil 25 and a positive electrode active material layer 26 formed of a positive electrode active material coated on both surfaces of the positive electrode metal foil 25. The positive electrode metal foil 25 of this embodiment is an aluminum foil. Both surfaces of the positive electrode metal foil 25 near the upper edge portion where the positive electrode tab 24 is provided are uncoated areas 25A where the positive electrode active material layer 26 is not applied. The positive electrode tab 24 of this embodiment is formed of a conductive adhesive tape, and one end of the positive electrode tab 24 is attached to an uncoated area 25 </ b> A of the positive electrode metal foil 25. As shown in FIGS. 4A to 4C, the conductive adhesive tape constituting the positive electrode tab 24 has a conductive adhesive (for example, conductive acrylic adhesive on one side of the tape-shaped rolled aluminum foil A. Agent) B is applied. The conductive adhesive tape before use is provided with a release paper (not shown) that covers the surface on which the conductive adhesive B is applied. The positive electrode tab 24 has a positive electrode tab bent portion M bent in the longitudinal direction, and the other end of the positive electrode tab 24 is directed in the bent direction.

  The negative electrode 22 has a rectangular negative electrode main body 27 and a strip-shaped negative electrode tab 28 formed at the edge of the negative electrode main body 27. The negative electrode body 27 includes a rectangular negative electrode metal foil 29 and a negative electrode active material layer 30 formed of a negative electrode active material coated on both surfaces of the negative electrode metal foil 29. The negative electrode metal foil 29 of this embodiment is a copper foil. Both surfaces of the negative electrode metal foil 29 near the upper edge where the negative electrode tabs 28 are provided are uncoated areas 29A where the negative electrode active material layer 30 is not applied. The negative electrode tab 28 of the present embodiment is formed of a conductive adhesive tape, and one end of the negative electrode tab 28 is attached to an uncoated area 29 </ b> A of the negative electrode metal foil 29. As shown in FIGS. 4 (a) to 4 (c), the conductive adhesive tape constituting the negative electrode tab 28 has a conductive adhesive (for example, conductive acrylic adhesive on one side of the tape-shaped rolled copper foil C). Agent) B is applied. The conductive adhesive tape before use is provided with a release paper (not shown) that covers the surface on which the conductive adhesive B is applied. The negative electrode tab 28 has a negative electrode tab bent portion N bent in the longitudinal direction, and the other end of the negative electrode tab 28 is directed in the bent direction.

  The electrode assembly 20 has a separator 31 that insulates between the positive electrode 21 and the negative electrode 22, and has a layered structure in which the plurality of positive electrodes 21 and the plurality of negative electrodes 22 are alternately stacked while maintaining an insulating state. For example, as shown in FIG. 5, the electrode assembly 20 is configured by laminating a plurality of positive electrodes 21 and a plurality of negative electrodes 22.

  The positive electrode tabs 24 are arranged in a line along the stacking direction of the electrode assemblies 20. The respective negative electrode tabs 28 are arranged in a row along the stacking direction like the positive electrode tabs 24 so as not to overlap with the positive electrode tabs 24. The other end portions of the positive electrode tabs 24 are attached to each other so as to overlap each other, and the multiple positive electrode tabs 24 form a positive electrode current collecting group 32. The other end of the positively bonded positive electrode tabs 24 forms a positive electrode aggregation portion 32A (see FIGS. 1 and 2). In the present embodiment, the length from one end to the other end is set to be different for each positive electrode tab 24. Similarly to the positive electrode tab 24, the other end of each negative electrode tab 28 is bonded and aggregated so as to overlap each other, and the many negative electrode tabs 28 form a negative electrode current collection group 33. The other end portion of the negative electrode tabs 28 adhered to each other forms a negative electrode aggregation portion 33A (see FIGS. 1 and 2). The negative electrode aggregation portion 33A is formed apart from the positive electrode aggregation portion 32A. In the present embodiment, the length from one end to the other end of each negative electrode tab 28 is set to be different.

  A positive current collector plate 34 is joined to the positive current collector group 32, and a negative current collector plate 35 is joined to the negative current collector group 33. The positive current collector group 32 and the positive current collector plate 34 are joined to the surface of the positive current collector group 32 to which the adhesive of the conductive adhesive tape that is the lowest position is applied, and the surface of the positive current collector plate 34. By sticking. The negative electrode current collecting group 33 and the negative electrode current collecting plate 35 are joined to the surface of the negative electrode current collecting group 33 on which the adhesive of the conductive pressure-sensitive adhesive tape is applied, and the surface of the negative electrode current collecting plate 35. By sticking. As shown in FIG. 2, the positive electrode current collector plate 34 is provided with a positive electrode terminal 37 that is electrically connected via an overcurrent protection circuit 36. Further, the negative electrode current collector plate 35 is provided with a negative electrode terminal 38 that is electrically connected via an overcurrent protection circuit 36. In a state where the electrode assembly 20 is accommodated in the battery case 11, the positive electrode terminal 37 and the negative electrode terminal 38 are exposed to the outside of the battery case 11 through the pair of through holes 17 of the lid body 14. A cylindrical insulating ring 39 made of resin for insulating the positive terminal 37 and the negative terminal 38 from the lid body 14 is attached to the positive terminal 37 and the negative terminal 38, respectively (see FIGS. 1 and 2). .

  The positive electrode current collector plate 34 and the negative electrode current collector plate 35 are rectangular flat plates as shown in FIG. The positive electrode current collecting plate 34 and the negative electrode current collecting plate 35 do not interfere with the inner surface of the case body 12 when bonded to the positive electrode current collecting group 32 and the negative electrode current collecting group 33.

  Next, manufacture of the electrode assembly 20 in the secondary battery 10 of this embodiment is demonstrated. First, the production of the positive electrode 21 will be described. The positive electrode active material layer 26 is formed on both surfaces of the positive electrode metal foil 25 manufactured in advance in a rectangular shape to obtain the positive electrode main body 23. An uncoated region 25A is formed on the positive electrode metal foil 25 coated with the positive electrode active material. Next, one end of the conductive adhesive tape to be the positive electrode tab 24 is attached to the uncoated area 25A. The positive electrode tab 24 is joined to and electrically connected to the positive electrode metal foil 25 by sticking to the uncoated area 25A. After the positive electrode tab 24 is joined to the positive electrode metal foil 25, the positive electrode tab 24 is bent (see FIGS. 4A to 4C). The electrode assembly 20 includes a large number of positive electrode main bodies 23, and the other ends of the positive electrode tabs 24 bonded to the respective positive electrode main bodies 23 are attached to each other (see FIG. 5).

  Next, the production of the negative electrode 22 will be described. A negative electrode active material layer 30 is formed on both surfaces of a negative electrode metal foil 29 that has been manufactured in a rectangular shape in advance to obtain a negative electrode main body 27. An uncoated region 29A is formed in the negative electrode metal foil 29 coated with the negative electrode active material. Next, one end portion of the conductive adhesive tape to be the negative electrode tab 28 is attached to the uncoated area 29A. The negative electrode tab 28 is bonded to and electrically connected to the negative electrode metal foil 29 by sticking to the uncoated area 29A. After joining the negative electrode tab 28 to the negative electrode metal foil 29, the negative electrode tab 28 is bent (see FIGS. 4A to 4C). The electrode assembly 20 has a large number of negative electrode main bodies 27, and the other ends of the negative electrode tabs 28 bonded to the respective negative electrode main bodies 27 are bonded to each other (see FIG. 5).

  As shown in FIG. 5, a separator 31 is interposed between the positive electrode 21 in which the positive electrode tab 24 is bonded to the positive electrode body 23 and the negative electrode 22 in which the negative electrode tab 28 is bonded to the negative electrode body 27, and a plurality of positive electrodes 21 and the plurality of negative electrodes 22 are alternately stacked while maintaining an insulating state. The multiple positive electrode tabs 24 are stacked so that the bending directions thereof coincide with each other, and the other ends of the multiple positive electrode tabs 24 are overlapped with each other. When the surface of the conductive adhesive of the overlapping positive electrode tab 24 is in close contact with the surface of the aluminum foil of the stacked positive electrode tab 24, the positive electrode tabs 24 are adhered to each other. All the positive electrode tabs 24 are attached to each other, so that a large number of positive electrode tabs 24 form a positive electrode current collecting group 32. A positive electrode current collecting plate 34 is joined to the positive electrode current collecting group 32. A positive electrode terminal 37 electrically connected via an overcurrent protection circuit 36 is provided in advance on the positive electrode current collector plate 34. A positive electrode current collector plate 34 is attached to the surface of the conductive adhesive of the conductive adhesive tape which is the lowest position in the positive electrode current collector group 32, and the positive electrode current collector plate 34 is joined to the positive electrode current collector group 32.

  The multiple negative electrode tabs 28 are stacked so that the bending directions thereof coincide with each other, and the other ends of the multiple negative electrode tabs 28 are overlapped with each other. The negative electrode tabs 28 are adhered to each other by the adhesive surface of the overlapping negative electrode tabs 28 being in close contact with the surface of the copper foil of the negative electrode tabs 28 to be stacked. All the negative electrode tabs 28 are attached to each other, whereby the negative electrode tabs 28 form a negative electrode current collecting group 33. A negative electrode current collecting plate 35 is joined to the negative electrode current collecting group 33. The negative electrode current collector plate 35 is previously provided with a negative electrode terminal 38 that is electrically connected via an overcurrent protection circuit 36. The negative electrode current collector plate 35 is attached to the surface of the conductive adhesive of the conductive adhesive tape that is the lowest position in the negative electrode current collector group 33, and the negative electrode current collector plate 35 is joined to the negative electrode current collector group 33.

  When the electrode assembly 20 is completed, the electrode assembly 20 is inserted into the case body 12, and the positive terminal 37 and the negative terminal 38 are inserted through the insulating ring 39 and the through hole 17 of the lid body 14, respectively. Thereafter, the lid 14 is joined to the case body 12 by welding, an electrolyte is injected from an injection port (not shown), and the injection port is sealed, whereby the assembly of the secondary battery 10 is completed.

According to the secondary battery 10 of the present embodiment, the following operational effects are obtained.
(1) By sticking one end of the conductive adhesive tape to the positive electrode main body 23, the positive electrode tab 24 can be formed by bonding. By sticking one end of the conductive adhesive tape to the negative electrode main body 27, the negative electrode tab 28 can be formed by bonding. Therefore, compared to the case of joining the positive electrode tab and the negative electrode tab by welding, it is easier to join, and the working time of joining can be shortened. Also, no equipment for welding is required. In particular, since the stacked electrode assembly 20 requires a large number of positive electrode tabs 24 and negative electrode tabs 28, the effect of shortening the working time by omitting welding is great.

(2) The positive electrode aggregation portion 32 </ b> A can be formed by mutually sticking the other end portion on the opposite side of the one end portion of the conductive adhesive tape attached to each of the plurality of positive electrode main bodies 23. Moreover, 33 A of negative electrode aggregation parts can be formed by mutually sticking the other edge part on the opposite side of the one edge part of the electroconductive adhesive tape each affixed on the some negative electrode main body 27. FIG. The positive electrode aggregation portion 32A and the negative electrode aggregation portion 33A can be easily formed by mutually adhering a plurality of conductive adhesive tapes.

(3) The positive electrode current collecting plate 34 is bonded to the positive electrode collecting portion 32A by sticking the positive electrode current collecting plate 34 as the positive electrode conductive portion to the surface of the conductive adhesive of the conductive adhesive tape in the positive electrode collecting portion 32A. be able to. Further, the negative electrode current collector plate 35 is bonded to the negative electrode aggregate portion 33A by sticking the negative electrode current collector plate 35 as the negative electrode conductive portion to the surface of the conductive adhesive of the conductive adhesive tape in the negative electrode aggregate portion 33A. Can do. Therefore, as compared with the case of joining of the positive electrode current collector plate 34 and the negative electrode current collector plate 35 by welding, it is easier to join, and the work time of joining can be shortened.

(4) The positive electrode tab bent portion M is formed by bending before mutual bonding, and the negative electrode tab bent portion N is formed by bending. Compared to the case where the positive electrode tabs 24 are bent together after the mutual attachment, the bending of the positive electrode tabs 24 can reduce the resistance to bending. Further, as compared with the case where the negative electrode tabs 28 are bent together after the mutual attachment, the bending of the negative electrode tabs 28 can reduce the resistance to bending. Also, no equipment for welding is required.

  Next, the secondary battery 10 according to the modification will be described. As shown in FIG. 6, in this modification, the positive electrode tab 24 and the negative electrode tab 28 are not positively bent. A positive electrode conductive portion (not shown) is bonded to the other end of the positive electrode tab 24 that is not bent by bonding. A negative electrode conductive portion (not shown) is bonded to the other end of the negative electrode tab 28 that is not bent. According to the secondary battery 10 according to this modification, the same effects as the operational effects (1) to (3) of the secondary battery 10 according to the embodiment are achieved.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist of the invention. For example, the following modifications may be made.

In the above embodiment (including modifications), a conductive adhesive tape in which a conductive adhesive is applied to a rolled aluminum foil is used as the positive electrode tab. However, the metal foil of the conductive adhesive tape is not necessarily a positive metal foil. The material may not be the same. Moreover, although the conductive adhesive tape by which the conductive adhesive was apply | coated to the rolled copper foil was used as a negative electrode tab, the metal foil of a conductive adhesive tape does not necessarily need to be the same material as a negative electrode metal foil.
○ In the above embodiment (including modifications), each positive electrode tab (negative electrode tab) has a different length (length from one end to the other end). ) Is not particularly limited. The positive electrode tab (negative electrode tab) should just be set to the length which can be mutually stuck by the other edge part.
In the above embodiment (including the modification), the secondary battery is illustrated as the power storage device. However, the power storage device is not limited to the secondary battery, and may be applied to a capacitor other than a battery such as an electric double layer capacitor. Also good.

DESCRIPTION OF SYMBOLS 10 Secondary battery 11 Battery case 20 Electrode assembly 21 Positive electrode 22 Negative electrode 23 Positive electrode main body 24 Positive electrode tab 27 Negative electrode main body 28 Negative electrode tab 31 Separator 32A Positive electrode collecting part 33A Negative electrode collecting part 34 Positive electrode current collecting plate 35 Negative electrode current collecting plate 37 Positive electrode terminal 38 Negative electrode terminal A Rolled aluminum foil B Conductive adhesive C Rolled copper foil M Positive electrode tab bent portion N Negative electrode tab bent portion

Claims (4)

A multilayer electrode assembly in which a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked while maintaining an insulating state,
The positive electrode includes a positive electrode main body and a strip-shaped positive electrode tab drawn from the positive electrode main body,
The negative electrode is a power storage device including a negative electrode main body and a strip-shaped negative electrode tab drawn from the negative electrode main body,
The positive electrode tab and the negative electrode tab are conductive adhesive tapes,
The positive electrode tab is attached to the positive electrode body,
The power storage device, wherein the negative electrode tab is attached to the negative electrode body. A positive electrode aggregation portion that aggregates a plurality of the positive electrode tabs in the stacking direction of the electrode assembly is formed,
A negative electrode aggregation part that aggregates a plurality of the negative electrode tabs in the stacking direction of the electrode assembly is formed apart from the positive electrode aggregation part,
The positive electrode aggregation portion is formed by mutually adhering a plurality of the positive electrode tabs,
The power storage device according to claim 1, wherein the negative electrode aggregation portion is formed by mutually adhering a plurality of the negative electrode tabs. The positive electrode conductive portion is bonded to the positive electrode aggregation portion by sticking,
The power storage device according to claim 2, wherein a negative electrode conductive portion is bonded to the negative electrode aggregation portion by bonding. The positive electrode tab has a positive electrode tab bent portion formed by bending before mutual sticking,
The power storage device according to claim 2, wherein the negative electrode tab has a negative electrode tab bent portion formed by bending before being attached to each other.

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