JP5811966B2 - Power storage device - Google Patents

Description

  The present invention relates to a 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 some of these secondary batteries, a belt-like positive electrode and a belt-like negative electrode are folded in a zigzag manner to form an electrode assembly (for example, Patent Document 1). In Patent Document 1, since the electrode assembly is formed by folding the positive electrode and the negative electrode, the manufacturing process is simplified and the electrode assembly is simplified as compared with the case of stacking the positive and negative electrodes in the form of a rectangular sheet (sheet-fed). Can be manufactured.

JP-A-9-35721

  However, in Patent Document 1, in each electrode, a current collecting tab is formed only in a portion disposed in the outermost layer of the electrode assembly in the stacking direction, and the current collecting tab and an electrode terminal formed on the case are provided. Electrically connected. For this reason, in each electrode, the current collection efficiency from the part spaced apart from the current collection tab falls, and there exists a possibility that the energy density of a secondary battery may become small in connection with this.

  The present invention has been made paying attention to the problems existing in the prior art, and an object of the present invention is to provide a power storage device that can easily form an electrode assembly and improve current collection efficiency. .

  In order to solve the above problems, the invention according to claim 1 is directed to an electrode assembly in which a first electrode and a second electrode having a different polarity from the first electrode overlap each other with a separator interposed therebetween. And a power storage device having a case in which the electrode assembly is accommodated and the first electrode terminal and the second electrode terminal are fixed, wherein the first electrode is a band-shaped electrode, and the second electrode The separator is folded in a zigzag manner in which a first flat portion overlapping with the first bent portion including a first bent portion and extending from a first edge portion of the first flat portion are alternately provided, A second flat surface that has a fixed surface to which the second electrode is fixed and is interposed between the first flat portions together with the second electrode fixed to the fixed surface and overlaps the first flat portion. And the second flat portion including the second bent portion A first separator folded in a zigzag manner in which second folds extending from a second edge perpendicular to the one edge are alternately provided, and a surface of the second electrode opposite to the fixed surface; A second separator interposed between the first electrode and at least one third edge among the third edges located at both ends in the extending direction of the first edge of the first electrode. The portion is provided with a first current collecting tab that protrudes from the third edge and is electrically connected to the first electrode terminal at a portion that is not covered by the second folded portion of the first separator. And the second of the two first separators facing each other on the opposite side of the fixed surface with the first flat portion of the first electrode interposed between the edges of the second electrode. The fourth edge on the side of the second folded portion provided continuously on both of the flat portions has the fourth edge From projecting, and summarized in that the second current collector tabs which are connected to the second electrode terminal electrically is provided.

  According to this, as compared with the case where the sheet-like first electrode and the second electrode are laminated by folding the first separator to which the second electrode is fixed and the belt-like first electrode in a folded manner, respectively. Thus, the electrode assembly can be easily formed. And the 4th edge by the side of the 2nd folding | turning part provided continuously in both of the 2nd plane part of two 1st separators in which the surface on the opposite side to a fixed surface opposes among the edge parts of a 2nd electrode. The part is provided with a protruding second current collecting tab electrically connected to the second electrode terminal. That is, the second current collecting tab is provided in the second folded portion that is an intermediate portion in the stacking direction of the electrode assembly. For this reason, both the first electrode and the second electrode are strip-shaped, and in the second electrode, the current collecting tab is formed only in the portion arranged in the outermost layer in the stacking direction in the electrode assembly. The separation distance between the second current collecting tab and each part of the second electrode can be reduced, and the current collecting efficiency can be improved.

  According to a second aspect of the present invention, in the power storage device according to the first aspect, the first current collection tab is the third edge on the direction side in which the second current collection tab projects out of the third edge. The gist is that the edge portion is formed at a position that does not overlap the second current collecting tab.

  According to this, since the first current collecting tab and the second current collecting tab are provided on one side of the electrode assembly, the connection structure between the first current collecting tab and the first electrode terminal, and the second current collecting tab are provided. The connection structure between the tab and the second electrode terminal can be easily simplified.

  According to a third aspect of the present invention, in the power storage device according to the first or second aspect, the two first separators in which the fixed surfaces face each other with the first flat portion of the first electrode interposed therebetween. The gist of the present invention is that one second electrode continuous to the two second plane portions is fixed to the second plane portion.

According to this, as compared with the case where one second electrode is fixed to each second flat portion, the operation of fixing the second electrode to the first separator can be simplified, and the electrode assembly can be formed easily.
According to a fourth aspect of the present invention, in the power storage device according to the third aspect, the second electrode includes a metal foil and an active material layer in which an active material is applied to a surface of the metal foil. The two electrodes are formed with an electrode bent portion bent along the second folded portion of the first separator, and the electrode bent portion is not coated with an active material on the surface of the metal foil. The gist is that the section is provided.

  According to this, since the active material layer is not formed in the electrode bent portion bent along the second folded portion, the electrode bent portion is easily bent together with the first separator, and the electrode assembly can be easily Can be formed.

  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 length along the protruding direction of the second current collecting tab is the first length of the first electrode. Along the first separator between the second electrodes fixed to both of the second flat portions of the two first separators opposite to each other in a state where the flat portion is interposed. The gist is that it is longer than the separation distance.

  According to this, it can suppress that the 2nd folding | turning part extended from a 2nd plane part enlarges by shortening the separation distance between the 2nd electrodes fixed to a 1st separator. Therefore, it can suppress that the energy density as an electrical storage apparatus falls.

  According to a sixth aspect of the present invention, in the power storage device according to any one of the first to fifth aspects, the first separator and the second separator are mutually in a state of sandwiching the second electrode. The gist is fixed.

  According to this, since the first and second separators are fixed to each other with the second electrode interposed therebetween, the first and second separators are separated from each other between the first electrode and the second electrode. Compared with the case where two separators are sandwiched, an electrode assembly can be formed more easily.

  The invention according to claim 7 is summarized in that, in the power storage device according to any one of claims 1 to 6, the first electrode is a negative electrode and the second electrode is a positive electrode. According to this, the positive electrode can be easily positioned by folding it in a zigzag manner with the positive electrode fixed to the first separator.

  The gist of an eighth aspect of the present invention is the power storage device according to any one of the first to seventh aspects, wherein the power storage device is a secondary battery. According to this, as a secondary battery, while being able to form an electrode assembly simply, current collection efficiency can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to form an electrode assembly simply, current collection efficiency can be improved.

Sectional drawing which shows a secondary battery typically. The perspective view which shows an electrode assembly typically. (A) is a top view which shows typically the expand | deployed electrode sheet body, (b) is the 1-1 sectional view taken on the line shown to (a). 2-2 sectional view taken on the line shown in FIG. The top view which shows typically the electrode sheet body in another embodiment. The top view which shows typically the electrode sheet body in another embodiment. The top view which shows typically the electrode sheet body in another embodiment.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, for example, a lithium ion secondary battery (hereinafter referred to as “secondary battery”) 10 as a power storage device mounted on a vehicle such as a passenger vehicle or an industrial vehicle includes a case 11 and an electrode assembly 12. Contained.

  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 14 as an electrolyte. Further, a positive electrode terminal 15 as a second electrode terminal and a negative electrode terminal 16 as a first electrode terminal are fixed to the lid member 11b which is one of the walls forming the case 11, and protrudes outward. .

  As shown in FIG. 2, the electrode assembly 12 includes a negative electrode sheet 20 as a first electrode that is a belt-like electrode, and a positive electrode sheet 30 as a second electrode in a rectangular sheet shape having a polarity different from that of the negative electrode sheet 20; A first separator 40 and a second separator 41 that insulate between the negative electrode sheet 20 and the positive electrode sheet 30 are provided. In addition, the 1st separator 40 and the 2nd separator 41 are the porous resin-made sheets which have insulation.

  In the electrode assembly 12, the electrode sheet body 50 formed by sandwiching the plurality of positive electrode sheets 30 with the second separator 41 and fixing to the first separator 40, and the negative electrode sheet 20 are each in a “zigzag shape”. Is a zigzag folded electrode assembly in which the negative electrode sheet 20, the positive electrode sheet 30, and the separators 40 and 41 are layered. In the following description, the direction in which the negative electrode sheet 20 and the positive electrode sheet 30 are overlapped in layers is simply indicated as a stacking direction Yc. The electrode assembly 12 is accommodated in the case 11 while being covered with an insulating sheet (not shown).

  In the electrode assembly 12, the negative electrode sheet 20 is equidistant along the longitudinal direction Ya of the negative electrode sheet 20 in a state where the longitudinal direction Ya of the negative electrode sheet 20 and the protruding directions of the positive electrode terminal 15 and the negative electrode terminal 16 are orthogonal to each other. A bent portion 21 as a first bent portion is provided by repeating mountain folds and valley folds, and is folded in a zigzag manner.

  In the present embodiment, a region A of the negative electrode sheet 20 that overlaps with the first separator 40 (electrode sheet body 50) when viewed from the stacking direction Yc becomes the negative electrode flat portion 22 as the first flat portion, and the first separator 40 (electrode sheet) The region B that does not overlap the body 50) becomes the negative electrode folded portion 23 as the first folded portion including the bent portion 21. The negative electrode plane portion 22 is also a region overlapping the positive electrode sheet 30 when viewed from the stacking direction Yc. In FIG. 2, the region A indicates a range from one edge portion to the other edge portion located at both ends in the width direction of the first separator 40 when viewed from the stacking direction Yc of the negative electrode sheet 20, and the region B is In the negative electrode sheet 20, the range from the edge part located in the both ends of the width direction of the 1st separator 40 to the bending part 21 is pointed out. The negative electrode folded portion 23 extends from the negative electrode boundary portion E1 as the first edge portion of the edge portion of the negative electrode flat surface portion 22. In the negative electrode sheet 20, the negative electrode flat portion 22 and the negative electrode folded portion 23 are provided alternately. Further, the negative electrode folded portion 23 is a portion not covered by the first separator 40.

  The negative electrode sheet 20 has a strip-shaped metal foil for negative electrode (copper foil in this embodiment) 25 and a negative electrode active material layer 26 formed by applying a negative electrode active material on both surfaces thereof. The portion of the metal foil 25 where the negative electrode active material layer 26 is not formed constitutes a non-coated portion 27.

  Further, among the edge portions extending along the longitudinal direction Ya of the negative electrode sheet 20 (metal foil 25), the negative electrode sheet is provided on the edge portion 20a as the third edge portion disposed on the negative electrode terminal 16 (lid member 11b) side. The negative electrode current collection tab 28 as a rectangular 1st current collection tab which protrudes along the width direction of 20 is provided at predetermined intervals. The edge 20a is also an edge located at both ends in the extending direction of the negative electrode boundary E1. Each negative electrode current collecting tab 28 is a metal foil 25 constituting the non-coated portion 27, and the negative electrode active material layer 26 is not formed on the surface. Each negative electrode current collecting tab 28 is provided on a flat folded flat surface portion 29 of the negative electrode folded portion 23 excluding the bent portion 21.

  The negative electrode current collecting tab 28 is provided in all the negative electrode folded portions 23. Further, the negative electrode current collecting tabs 28 are provided on all the folded plane portions 29. The negative electrode current collecting tabs 28 are provided so that the bent portions 21 of the respective negative electrode folded portions 23 arranged on the negative electrode terminal 16 side are close to each other so as to be sandwiched from both sides in the longitudinal direction Ya when the negative electrode sheet 20 is unfolded. Yes. And the two negative electrode current collection tabs 28 provided in one negative electrode folding | returning part 23 mutually overlap in the lamination direction Yc in the state which folded the negative electrode sheet 20. FIG. The negative electrode current collecting tab 28 is also provided at the edge portion 20a at the end portion (start end portion and end portion) 29e in the longitudinal direction Ya of the negative electrode sheet 20 protruding from the negative electrode flat portion 22.

  For this reason, in the state where the negative electrode sheet 20 is folded, the negative electrode current collecting tab 28 is layered on one of the edges of the electrode assembly 12 that is disposed on the negative electrode terminal 16 (lid member 11b) side. The overlapping negative electrode current collecting tab group 28 a is projected along the width direction of the negative electrode sheet 20. As shown in FIG. 1, the negative electrode current collecting tab group 28a is joined and electrically connected to the negative electrode terminal 16 by resistance welding or the like in a state where the negative electrode current collecting tabs 28 are gathered in the stacking direction Yc. ing.

  As shown in FIG. 2, in the electrode assembly 12, the first separator 40 constituting the electrode sheet body 50 has the longitudinal direction Yb of the first separator 40 and the longitudinal direction Ya of the negative electrode sheet 20 orthogonal to each other. In this state, a bent portion 42 as a second bent portion is provided by repeating mountain folds and valley folds at equal intervals along the longitudinal direction Yb of the first separator 40 and is folded in a zigzag manner.

  In the present embodiment, the region C of the first separator 40 that overlaps with the negative electrode sheet 20 when viewed from the stacking direction Yc becomes the separator flat portion 43 as the second flat portion, and the region that does not overlap with the negative electrode sheet 20 includes the bent portion 42. It becomes the separator folding | turning part 44 as a 2nd folding | turning part. In FIG. 2, a region C indicates a range from one edge 20 a to the other edge 20 b located at both ends in the width direction of the negative electrode sheet 20 when viewed from the stacking direction Yc in the first separator 40.

  That is, the separator folding portion 44 extends from the separator boundary portion E2 as the second edge portion orthogonal to the negative electrode boundary portion E1 in the separator flat portion 43. In the 1st separator 40, the separator plane part 43 and the separator folding | turning part 44 are provided alternately.

  As shown in FIGS. 3A and 3B, a plurality of positive electrode sheets 30 are fixed to a fixed surface 40 a that is one surface of the surfaces of the first separator 40. In the first separator 40, the positive electrode sheet 30 is not fixed to the opposite surface 40b that is the surface opposite to the fixed surface 40a.

  Each positive electrode sheet 30 constituting the electrode sheet body 50 includes a positive electrode metal foil (aluminum foil in the present embodiment) 31 and a positive electrode active material layer 32 formed by applying a positive electrode active material on both surfaces thereof. The metal foil 31 is a rectangular sheet that extends along the longitudinal direction Yb of the first separator 40 in a state in which the electrode sheet body 50 is unfolded, and is slightly smaller than two separator plane portions 43 adjacent to each other with the bent portion 42 interposed therebetween. Metal foil.

  As shown in FIG. 2, the length of the metal foil 31 along the width direction of the first separator 40 is shorter than the interval between the bent portions 21 in the negative electrode sheet 20. Moreover, the length of the formation part of the positive electrode active material layer 32 along the longitudinal direction Yb of the first separator 40 is shorter than the length of the negative electrode sheet 20 in the width direction.

  Moreover, as shown in FIG. 3, the metal foil 31 of the part in which the positive electrode active material layer 32 is not formed comprises the non-coating part 33 as an uncoated part. The uncoated portion 33 is provided at a constant width across the entire width in the width direction at the center of the metal foil 31 in the longitudinal direction Yb in a state where the electrode sheet body 50 is developed. Further, the non-coated portion 33 is provided at a position where the bent portion 42 (separator folded portion 44) overlaps the center of the non-coated portion 33 in the longitudinal direction Yb in a state where the electrode sheet body 50 is unfolded. That is, the positive electrode sheet 30 is formed with an electrode bent portion 30c that is bent along the bent portion 42 (separator folded portion 44) of the first separator 40. The electrode bent portion 30c includes an uncoated portion. 33 is provided.

  Moreover, in the positive electrode sheet 30 (metal foil 31), the edge portion 30a as one fourth edge portion of the edge portions extending along the width direction (longitudinal direction Ya) of the first separator 40 includes the edge portion. A positive electrode current collecting tab 34 is provided as a rectangular second current collecting tab protruding from 30a along the longitudinal direction Yb. The positive electrode current collecting tab 34 is a part of the metal foil 31 constituting the non-coated portion 33, and the positive electrode active material layer 32 is not formed on the surface.

  The length of the positive electrode current collecting tab 34 along the protruding direction (longitudinal direction Yb) is longer than the distance from the edge 30a where the positive electrode current collecting tab 34 is provided to the bent portion 42. Moreover, the length along the protruding direction of the positive electrode current collecting tab 34 is shorter than the separation distance along the first separator 40 between the adjacent positive electrode sheets 30 in the first separator 40. In the present embodiment, in the positive electrode sheet 30, the positive electrode current collecting tab 34 is not provided on the other edge portion 30b of the edge portions extending along the width direction of the first separator 40.

  In addition, each positive electrode sheet 30 has a rectangular sheet-shaped second separator 41 that is slightly larger than the positive electrode sheet 30 and the above-described first separator 40, and the positive electrode current collecting tab from the edge of the second separator 41. 34 are sandwiched in a state where the leading end side of 34 protrudes along the longitudinal direction Yb. The second separator 41 is joined and fixed to the first separator 40 along the peripheral edge by, for example, heat welding.

  That is, the positive electrode sheet 30 is accommodated in an electrode accommodating portion formed by the first separator 40 and the second separator 41, respectively. Thereby, each positive electrode sheet 30 is formed on the first separator 40 in a state where the entire surface including the positive electrode active material layer 32 is covered with the first separator 40 and the second separator 41 except for the front end side of the positive electrode current collecting tab 34. It is fixed.

  The electrode assemblies 12 are alternately overlapped with each other in a state where the longitudinal direction of the negative electrode sheet 20 in the unfolded state and the longitudinal direction Yb of the first separator 40 (electrode sheet body 50) are orthogonal to each other. It is formed by folding.

  Here, the first separator 40 (electrode sheet body 50) has an edge portion 30a of the positive electrode sheet 30 and another adjacent to the positive electrode sheet 30 in a state where the electrode sheet body 50 is expanded as indicated by an arrow Y1. The separator folded portion 44 sandwiched between the positive electrode sheet 30 and the edge portion 30b is folded into a mountain with respect to the fixed surface 40a, and a bent portion 42 is provided. That is, each bent portion 42 is provided by bending a separator folded portion 44 that does not overlap with each positive electrode sheet 30 in the first separator 40.

  In addition, the first separator 40 (electrode sheet body 50) is fixed at the separator folding portion 44 that overlaps with the non-coated portion 33 of the positive electrode sheet 30 in a state where the electrode sheet body 50 is unfolded as indicated by an arrow Y2. Each of the surfaces 40a is valley-folded and a bent portion 42 is provided.

  Therefore, as shown in FIG. 4, separator flat portions 43 are interposed between the negative electrode flat portions 22 of the negative electrode sheet 20 together with the positive electrode sheets 30 fixed to the fixing surfaces 40 a. The second separator 41 is interposed between the surface of the positive electrode sheet 30 opposite to the fixed surface 40 a and the negative electrode sheet 20. And in this embodiment, the edge part 20a in which the negative electrode current collection tab 28 is provided is the edge part of the two separator plane parts 43 which opposite surfaces 40b oppose among the edge parts extended along the longitudinal direction Ya of the negative electrode sheet 20. The bent portion 42 of the separator folding portion 44 that is continuously provided on both sides, that is, the edge portion on the bent portion 42 side that is mountain-folded with respect to the fixed surface 40a. In other words, the negative electrode current collecting tab 28 is formed at a position that does not overlap the positive electrode current collecting tab 34 in the edge portion 20 a on the side of the negative electrode sheet 20 in the direction in which the positive electrode current collecting tab 34 protrudes.

  Further, in the present embodiment, the two separator flat portions 43 facing each other with the fixed surfaces 40 a facing each other with the negative electrode flat portion 22 interposed therebetween are continuous with the two separator flat portions 43 along the first separator 40. It can be said that the two positive electrode sheets 30 are fixed. That is, in the electrode assembly 12, the positive electrode sheet 30 is divided so as to correspond to the bent portion 42 that is at least a mountain fold with respect to the fixed surface 40a. In the positive electrode sheet 30, the non-coating portion 33 is provided in the electrode bent portion 30 c that is bent along the separator folded portion 44 (bent portion 42) that is a valley fold with respect to the fixed surface 40 a.

  Further, since the first separator 40 is folded back at the position opposite to the positive electrode terminal 15 from the tip of the positive electrode current collecting tab 34, the positive electrode current collecting tab 34 is respectively along the extending direction of the separator folded portion 44. , And protrudes toward the positive electrode terminal 15 side from the bent portion 42. That is, in the present embodiment, the positive electrode current collecting tab 34 is continuous with both of the two separator flat portions 43 facing each other with the opposite surfaces 40b facing each other with the negative electrode flat portion 22 interposed therebetween. The separator folding portion 44 is provided at the bent portion 42, that is, at the edge portion 30a on the bent portion 42 side which is a mountain fold with respect to the fixed surface 40a.

  Further, as shown in FIG. 2, one edge disposed on the positive electrode terminal 15 (lid member 11 b) side of the edge portion of the electrode assembly 12 in a state where the first separator 40 (electrode sheet body 50) is folded. A positive electrode current collecting tab group 34 a in which the positive electrode current collecting tabs 34 are stacked in a projecting manner is provided on the portion along the extending direction of the separator folded portion 44. As shown in FIG. 1, the positive electrode current collecting tab group 34a is joined and electrically connected to the positive electrode terminal 15 by resistance welding or the like in a state where the positive electrode current collecting tabs 34 are gathered in the stacking direction Yc. ing.

Next, the operation of the secondary battery 10 configured as described above will be described.
The electrode assembly 12 of the present embodiment is formed by folding the belt-shaped negative electrode sheet 20 and the first separator 40 (electrode sheet body 50) to which the positive electrode sheet 30 is fixed, into a rectangular shape. Compared with the case where the sheet-like (sheet-fed) negative electrode sheets 20 and the positive electrode sheets 30 are alternately laminated, the electrode assembly 12 can be easily formed.

  A positive electrode current collecting tab 34 is projected from an edge portion 30 a provided on the bent portion 42 side that is a mountain fold among the edge portions of the positive electrode sheet 30. That is, one positive electrode current collecting tab 34 is provided for each positive electrode sheet 30 fixed to one of the two separator flat portions 43. Therefore, as in the prior art, the negative electrode sheet 20 and the positive electrode sheet 30 are both strip-shaped, and the positive electrode current collecting tab is formed only on the portion of the positive electrode sheet 30 that is disposed in the outermost layer in the stacking direction of the electrode assembly. As compared with the above, the separation distance between the positive electrode current collecting tab 34 and each part in the positive electrode sheet 30 can be reduced.

  Moreover, the edge part 20a in which the negative electrode current collection tab 28 is provided is an edge part by the side of the direction where the positive electrode current collection tab 34 protrudes among the edge parts extended along the longitudinal direction Ya of the negative electrode sheet 20. FIG. Therefore, in the present embodiment, since the negative electrode current collecting tab 28 and the positive electrode current collecting tab 34 are provided on one side (lid member 11b) side of the electrode assembly 12, the connection between the negative electrode current collecting tab 28 and the negative electrode terminal 16 is provided. The structure and the connection structure between the positive electrode current collecting tab 34 and the positive electrode terminal 15 can be easily simplified.

  In particular, in the present embodiment, in the electrode assembly 12, the current collecting tabs 28 and 34 are protruded toward the lid member 11 b provided with the terminals 15 and 16. Can be easily connected to each of the terminals 15 and 16.

  Further, in the first separator 40, one positive electrode sheet 30 continuous along the first separator 40 is fixed to two adjacent separator flat portions 43. Therefore, the work of fixing the positive electrode sheet 30 to the first separator 40 can be simplified as compared with the case of fixing the positive electrode sheet 30 to each separator flat portion 43 one by one.

  In addition, a non-coating portion 33 is provided on the electrode bent portion 30 c of the positive electrode sheet 30. For this reason, the electrode bending part 30c can be bent easily with the 1st separator 40, and the electrode assembly 12 can be formed simply.

  The first separator 40 and the second separator 41 are fixed to each other with the positive electrode sheet 30 interposed therebetween. For this reason, compared with the case where the second separator 41 is sandwiched between the negative electrode sheet 20 and the positive electrode sheet 30 separately while folding the negative electrode sheet 20 and the first separator 40 to which the positive electrode sheet 30 is fixed, The electrode assembly 12 can be formed easily. In addition, since the positive electrode sheet 30 is fixed to the first separator 40, the positive electrode sheet 30 can be easily positioned with respect to the negative electrode sheet 20.

  In addition, since each negative electrode folded portion 23 of the negative electrode sheet 20 is provided with the negative electrode current collecting tab 28, the separation distance between the negative electrode current collecting tab 28 and each portion of the negative electrode sheet 20 can be reduced. In particular, in this embodiment, the negative electrode current collecting tabs 28 are provided in all the negative electrode folding parts 23, or two (plural) negative electrode current collecting tabs 28 are provided in each negative electrode folding part 23. Therefore, in this embodiment, the separation distance between the negative electrode current collecting tab 28 and each part of the negative electrode sheet 20 can be further reduced and averaged.

  Further, the negative electrode current collecting tab 28 is provided on the folded flat surface portion 29 of the negative electrode folded portion 23. Therefore, as compared with the configuration in which the negative electrode current collecting tab 28 is provided in the bent portion 21, the plurality of negative electrode current collecting tabs 28 are easily gathered and can be easily connected to the negative electrode terminal 16.

Therefore, according to the present embodiment, the following effects can be obtained.
(1) The electrode assembly 12 can be easily formed by folding the first separator 40 (electrode sheet body 50) to which the positive electrode sheet 30 is fixed and the strip-shaped negative electrode sheet 20 into a folded shape. A positive electrode current collecting tab 34 is projected from an edge portion 30 a provided on the bent portion 42 side that is a mountain fold among the edge portions of the positive electrode sheet 30. That is, the positive electrode current collecting tab 34 is provided in the separator folding portion 44 that is an intermediate portion in the stacking direction Yc of the electrode assembly 12. For this reason, the separation distance of the positive electrode current collection tab 34 and each part in the positive electrode sheet 30 can be made small. For this reason, current collection efficiency can be improved as the secondary battery 10.

  (2) The negative electrode current collecting tab 28 is formed at a position where it does not overlap the positive electrode current collecting tab 34 at the edge 20a on the side in which the positive electrode current collecting tab 34 protrudes. Accordingly, since the negative electrode current collecting tab 28 and the positive electrode current collecting tab 34 are provided on one side of the electrode assembly 12, the connection structure between the negative electrode current collecting tab 28 and the negative electrode terminal 16, and the positive electrode current collecting tab 34 and the positive electrode are provided. The connection structure with the terminal 15 can be easily simplified.

  (3) In particular, in the present embodiment, the current collecting tabs 28 and 34 are protruded toward the lid member 11b provided with the terminals 15 and 16, respectively. It can be easily connected to the terminals 15 and 16 in close proximity.

  (4) In the first separator 40, one positive electrode sheet 30 continuous to the two separator flat portions 43 is fixed to two adjacent separator flat portions 43. Therefore, the work of fixing the positive electrode sheet 30 to the first separator 40 can be simplified as compared with the case where the positive electrode sheet 30 is fixed to each separator flat portion 43 one by one.

  (5) The non-coated portion 33 is provided on the electrode bent portion 30 c of the positive electrode sheet 30. For this reason, the electrode bending part 30c can be bent easily with the 1st separator 40, and the electrode assembly 12 can be formed simply.

  (6) The first separator 40 and the second separator 41 are fixed to each other with the positive electrode sheet 30 interposed therebetween. Therefore, when the electrode assembly 12 is formed, the electrode assembly 12 can be easily formed as compared with the case where the second separator 41 is sandwiched separately from the negative electrode sheet 20 and the electrode sheet body 50.

(7) The positive electrode sheet 30 is fixed to the first separator 40. Therefore, the positive electrode sheet 30 can be easily positioned with respect to the negative electrode sheet 20.
(8) As a secondary battery, the electrode assembly 12 can be easily formed and the current collection efficiency can be improved.

The embodiment is not limited to the above, and may be embodied as follows, for example.
In the positive electrode sheet 30, the positive electrode current collection tab 34 may be provided in a different part, or multiple positive electrode current collection tabs 34 may be provided. For example, as shown in FIG. 5, each positive electrode sheet 30 may be provided with a positive electrode current collecting tab 34 at the edge 30b in addition to or instead of the edge 30a. Moreover, you may provide the some positive electrode current collection tab 34 in the edge part 30a and the edge part 30b of the positive electrode sheet 30, respectively.

  A single positive electrode sheet 30 may be fixed to one separator flat portion 43. In this case, for example, as shown in FIG. 6, among the edges of each positive electrode sheet 30, positive current collector tabs 34 are respectively provided on the edges 30 a and 30 b on the side of the bent portion 42 that is mountain-folded with respect to the fixed surface 40 a. Good. That is, the positive electrode sheet 30 may be divided so as to correspond to the bent portions 42 that are valley-folded with respect to the fixed surface 40a. A plurality of positive electrode sheets 30 arranged in the width direction of the first separator 40 may be fixed to one separator plane portion 43.

  As shown in FIG. 7, the length along the protruding direction of the positive electrode current collecting tab 34 is such that the opposite surfaces 40 b opposite to the fixed surface 40 a with the negative electrode flat portion 22 of the negative electrode sheet 20 interposed therebetween. It may be longer than the separation distance along the first separator 40 between the positive electrode sheets 30 fixed to both of the two separator flat portions 43 facing each other. According to this, by shortening the separation distance between the positive electrode sheets 30 fixed to the first separator 40, it is possible to suppress the separator turn-up portion 44 extending from the separator flat portion 43 from increasing in size. Therefore, it can suppress that the energy density as the secondary battery 10 falls.

The negative electrode sheet 20 may form the negative electrode active material layer 26 only in the negative electrode flat part 22 or only in a region including the negative electrode flat part 22 and slightly larger than the negative electrode flat part 22.
The positive electrode sheet 30 may form the positive electrode active material layer 32 on the entire surface of the metal foil 31 excluding the positive electrode current collecting tab 34. That is, the positive electrode active material layer 32 may be formed on the electrode bent portion 30c.

  In the bent part 21 of the negative electrode sheet 20, the non-coated part 27 may be provided by not forming the negative electrode active material layer 26. According to this, the negative electrode sheet 20 can be easily bent, and the electrode assembly 12 can be easily formed.

The electrode sheet 50 may be configured by fixing the negative electrode sheet 20 to the first separator 40 instead of the positive electrode sheet 30.
One or three or more positive electrode current collecting tabs 34 may be provided in the negative electrode folded part 23, and the negative electrode current collecting tabs 28 may be provided in some negative electrode folded parts 23.

(Circle) the negative electrode current collection tab 28 may be provided in the edge part 20b by the side of the bending part 42 in the separator folding | turning part 44 used as a valley fold.
The negative electrode current collecting tab 28 may be provided in a portion of the edge of the negative electrode flat surface portion 22 of the negative electrode sheet 20 that is not covered with the separator folded portion 44 of the first separator 40. By doing so, the negative electrode folding | returning part 23 can be made small.

In addition to the bent part 42, the separator folded part 44 of the first separator 40 (electrode sheet body 50) may have a flat part.
The second separator 41 may not be fixed to the first separator 40. For example, the first separator 40 to which the positive electrode sheet 30 is fixed and the belt-like second separator 41 may be folded in a zigzag manner in a state of being overlapped. In this case, the positive electrode sheet 30 and the first separator 40 are fixed by heat welding or the like.

The positive current collecting tab 34 and the negative current collecting tab 28 may be changed to different shapes such as a triangle and a semicircle.
The electrode assembly 12 may be formed by combining a plurality of negative electrode sheets 20.

The positive electrode sheet 30 and the negative electrode sheet 20 may be formed by applying an active material on one side.
O You may actualize in electrical storage apparatuses, such as a nickel hydride secondary battery and an electric double layer capacitor.

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

  E1 ... negative electrode boundary (first edge), E2 ... separator boundary (second edge), 10 ... lithium ion secondary battery (secondary battery, power storage device), 11 ... case, 12 ... electrode assembly, DESCRIPTION OF SYMBOLS 15 ... Positive electrode terminal (2nd electrode terminal), 16 ... Negative electrode terminal (1st electrode terminal), 20 ... Negative electrode sheet (1st electrode, negative electrode), 20a ... Edge part (3rd edge part), 21 ... Bending part ( 1st bent part), 22 ... negative electrode flat part (first flat part), 23 ... negative electrode folded part (first folded part), 28 ... negative electrode current collecting tab (first current collecting tab), 30 ... positive electrode sheet (first 2 electrodes, positive electrode), 30a ... edge (fourth edge), 30b ... edge, 30c ... electrode bent part, 31 ... metal foil, 32 ... positive electrode active material layer, 33 ... non-coated part (uncoated) Part), 34 ... positive electrode current collecting tab (second current collecting tab), 40 ... first separator, 40a ... fixed surface, 40b ... opposite surface, 41 ... second Separator, 42 ... bent portion (second bend), 43 ... separator plane portion (second flat portion), 44 ... separator folded portion (second folded part).

Claims (8)

A first electrode and a second electrode having a polarity different from that of the first electrode, and an electrode assembly that overlaps in a layered state with a separator interposed therebetween; a first electrode terminal that houses the electrode assembly; A power storage device having a case in which two electrode terminals are fixed,
The first electrode is a band-shaped electrode, and includes a first flat portion overlapping the second electrode, a first folded portion including a first bent portion and extending from a first edge portion of the first flat portion. Are folded in a zigzag pattern that is provided alternately,
The separator is strip-shaped and has a fixed surface to which the second electrode is fixed, and is interposed between the first plane portions together with the second electrode fixed to the fixed surface, and the first plane portion and The overlapping second plane part and the second folded part including the second bent part and extending from the second edge part orthogonal to the first edge part in the second plane part are folded in a zigzag manner. A first separator;
A second separator interposed between the surface of the second electrode opposite to the fixed surface and the first electrode;
A portion not covered by the second folded portion of the first separator on at least one third edge portion among the third edge portions located at both ends in the extending direction of the first edge portion of the first electrode. A first current collecting tab protruding from the third edge and electrically connected to the first electrode terminal;
Of the edge portions of the second electrode, the surfaces of the second plane portions of the two first separators facing each other on the opposite side to the fixed surface with the first plane portion of the first electrode interposed. A second current collecting tab that protrudes from the fourth edge and is electrically connected to the second electrode terminal is provided at the fourth edge on the second folded portion side that is provided continuously on both sides. A power storage device.   The first current collecting tab is formed at a position that does not overlap the second current collecting tab in the third edge of the third edge on the side in which the second current collecting tab protrudes. Item 2. The power storage device according to Item 1.   In the state where the first plane portion of the first electrode is interposed, the second plane portions of the two first separators that face each other with the fixed surfaces are continuous with the two second plane portions. The power storage device according to claim 1 or 2, wherein the second electrode is fixed. The second electrode has a metal foil and an active material layer obtained by applying an active material to the surface of the metal foil,
The second electrode is formed with an electrode bent portion bent along the second folded portion of the first separator, and the electrode bent portion is not coated with an active material on the surface of the metal foil. The power storage device according to claim 3, wherein a coating part is provided.   The length of the second current collecting tab along the protruding direction is such that the two surfaces of the first electrode opposite to the fixed surface face each other with the first flat portion of the first electrode interposed therebetween. The power storage device according to claim 1, wherein the power storage device is longer than a separation distance along the first separator between the second electrodes fixed to both of the second flat portions of the separator.   The power storage device according to claim 1, wherein the first separator and the second separator are fixed to each other with the second electrode interposed therebetween.   The power storage device according to claim 1, wherein the first electrode is a negative electrode and the second electrode is a positive electrode.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.