JP2013254705A - Power storage device and method for manufacturing electrode assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the improvement of manufacturing efficiency.SOLUTION: A positive-pole electrode 18 is provided with a positive electrode tab 24 at a position at which a positive electrode virtual center line L1 goes through. The positive pole electrode 18 is a positive electrode sheet 30 by being sandwiched by a pair of separators 20. The positive pole electrode 18 in the positive electrode sheet body 30 is arranged such that a virtual center line F of the positive pole sheet body 30 coincides with a positive electrode virtual center line L1 of the positive pole electrode 18. The positive electrode sheet body 30 is folded in a zigzag shape. Thus, positive electrode tabs 24 of respective positive pole electrodes 18 are overlapped in a lamination direction of the positive pole electrode 18 and a negative pole electrode 19 when constituting an electrode assembly.

Description

  The present invention relates to a power storage device having a zigzag folded electrode assembly and a method for manufacturing the electrode assembly.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. This type of secondary battery is disclosed in Patent Documents 1 and 2, for example. A secondary battery is a layered electrode assembly in which a negative electrode in which a negative electrode active material is applied to a metal foil and a positive electrode in which a positive electrode active material is applied to a metal foil are insulated with a separator made of a microporous film. It has a solid.

Japanese Utility Model Publication No. 56-24065 JP 2011-181395 A

  The electrode assemblies disclosed in Patent Documents 1 and 2 are obtained by sandwiching either the positive electrode or the negative electrode between a pair of separators, bending the separator in a zigzag shape, and interposing another electrode between the bendings. It is. The manufacture of such an electrode assembly is more efficient than the case where a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated. However, in recent years, further efficiency in manufacturing has been demanded from the viewpoint of manufacturing cost and the like.

  The present invention has been made paying attention to such problems existing in the prior art, and an object of the present invention is to provide a power storage device and an electrode assembly manufacturing method capable of improving manufacturing efficiency. It is in.

  In order to solve the above-described problem, the power storage device according to claim 1 is folded in a zigzag manner in which one or more first electrodes are sandwiched between sheet-like separators, and bending portions and linear portions are alternately provided. An electrode assembly having an electrode sheet having a laminated structure, and a plurality of second electrodes having a polarity different from that of the first electrode interposed between adjacent linear portions of the electrode sheet, and the electrode assembly , A first electrode terminal fixed to the case and electrically connected to the first electrode, and a second electrode terminal fixed to the case and electrically connected to the second electrode A first current collector that is electrically connected to the first electrode terminal on one side of the first electrode that is orthogonal to the direction in which the bent portion extends and that extends along the straight line portion. A tab is provided protrudingly, The two electrodes are provided with protruding second current collecting tabs that are electrically connected to the second electrode terminal on one side of the first electrode on the same side as the one side, and are disposed on both sides of the linear portion. The first current collecting tab is provided at a position through which the virtual center line passes when the virtual center line passing through the center between the bent portions and extending along the extending direction of the bent portion is defined. The current collecting tab is provided at a position where at least a part of the second current collecting tabs provided on each second electrode overlaps in the stacking direction, but does not overlap with the first current collecting tab in the stacking direction. This is the gist.

  The invention according to claim 7 is an electrode sheet body having a laminated structure in which one or more first electrodes are sandwiched between sheet-like separators and folded in a zigzag manner in which bent portions and straight portions are alternately provided, And a method of manufacturing an electrode assembly having a plurality of second electrodes having different polarities from the first electrodes respectively interposed between adjacent linear portions in the electrode sheet body, wherein the first electrode comprises: One side of the first electrode that is electrically connected to a first electrode terminal that is fixed to a case that houses the electrode assembly, the first electrode being orthogonal to a direction in which the bent portion extends and along the straight portion A first current collecting tab that is electrically connected to the first electrode terminal is protruded, and the second electrode is electrically connected to a second electrode terminal that is fixed to the case; The electrode includes the first electrode A second current collecting tab that is electrically connected to the second electrode terminal protrudes on one side of the same side as the side, passes through the center between the bent portions disposed on both sides of the linear portion, and passes through the bent portion. The first current collecting tab is provided at a position where the virtual center line passes, and the second current collecting tab is provided on each second electrode. At least a portion of the second current collecting tabs overlapped in the stacking direction, while the first current collecting tab is provided at a position not overlapping in the stacking direction, and the electrode is sandwiched between the first electrode and the separator A sheet body is formed, the electrode sheet body is folded in a zigzag shape, and the first electrode and the second electrode are alternately arranged by interposing the second electrode between straight portions of the electrode sheet body. The idea of layering That.

  According to these inventions, when the first current collecting tab of the first electrode defines a virtual center line that passes through the center between the bent portions arranged on both sides of the straight portion and extends along the direction in which the bent portion extends. Are provided at positions where the virtual center line passes. For this reason, when the electrode sheet body which pinched | interposed the 1st electrode with the separator is folded in a zigzag shape, the 1st current collection tab of each 1st electrode overlaps in the position where a virtual center line passes. That is, the 1st current collection tab of each 1st electrode overlaps in the lamination direction of an electrode assembly. Therefore, the electrode sheet body can be easily manufactured without arranging the first electrode in consideration of the folded state. That is, the efficiency of manufacturing the electrode assembly can be improved. As a result, the efficiency of manufacturing the power storage device can be improved.

  According to a second aspect of the present invention, in the power storage device according to the first aspect, the electrode sheet body includes a plurality of first electrodes, and each first electrode is disposed on the linear portion. It is a summary. According to this, the manufacture of a 1st electrode becomes easy by making the 1st electrode pinched | interposed into an electrode sheet body into a discontinuous sheet form. Further, the first electrode can be easily arranged.

  According to a third aspect of the present invention, in the power storage device according to the second aspect, the first electrode has a center of the first current collecting tab in a direction orthogonal to a direction in which the bent portion extends. The main point is that it is arranged at a position that passes through the center of the one side and that coincides with the virtual electrode center line extending along the direction in which the bent portion extends.

  According to this, since the first electrode is arranged at a position where the center of the first current collecting tab coincides with the virtual electrode center line, the first current collecting tab of each first electrode is securely placed on the virtual center line, that is, the electrode. They can be overlapped in the stacking direction of the assembly. Therefore, it is possible to increase the efficiency of manufacturing the electrode sheet body without arranging the first electrode in consideration of the folded state. That is, the efficiency of manufacturing the electrode assembly can be improved.

  Invention of Claim 4 is the electrical storage apparatus of Claim 2 or Claim 3, The said electrode sheet body has the junction part which joins the separators which pinch | interpose the said 1st electrode around the said 1st electrode. It is characterized by having. According to this, a 1st electrode can be wrapped with a separator by a junction part, and position shift of the 1st electrode can be controlled.

  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 first electrode is a positive electrode, and the second electrode is a negative electrode. This is the gist. According to this, the positive electrode can be easily positioned by folding the electrode sheet with the positive electrode sandwiched between the separators in a zigzag manner.

  A sixth aspect of the present invention is summarized as the power storage device according to any one of the first to fifth aspects, wherein the power storage device is a secondary battery. According to this, the manufacturing efficiency of the secondary battery can be improved.

  According to the present invention, the manufacturing efficiency can be improved.

The partially broken perspective view of a secondary battery. FIG. 1 is a sectional view taken along line 1-1 of FIG. (A) is a front view of a positive electrode, (b) is 2-2 sectional view taken on the line of (a). (A) is a front view of a negative electrode, (b) is the 3-3 sectional view taken on the line of (a). (A)-(c) is a conceptual diagram which shows the concept folded in zigzag shape. (A)-(c) is a conceptual diagram which shows the concept folded in zigzag shape. The front view which shows the positive electrode of another example. The front view which shows the positive electrode of another example.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, in a secondary battery 10 as a power storage device, an electrode assembly 12 is accommodated in a case 11. The case 11 includes a rectangular parallelepiped main body member 13 and a rectangular flat plate-shaped lid member 14. The lid member 14 closes the insertion port 13 a for inserting the electrode assembly 12 into the main body member 13. Both the main body member 13 and the lid member 14 constituting the case 11 are made of metal (for example, stainless steel or aluminum). Further, the secondary battery 10 of the present embodiment is a prismatic battery whose appearance is square. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

  A positive electrode terminal 15 as a first electrode terminal and a negative electrode terminal 16 as a second electrode terminal for taking out electricity from the electrode assembly 12 are electrically connected to the electrode assembly 12. The positive electrode terminal 15 and the negative electrode terminal 16 are each attached with a ring-shaped insulating ring 17 a for insulating from the case 11. The positive terminal 15 and the negative terminal 16 are fixed to the case 11.

  As shown in FIGS. 1 and 2, the electrode assembly 12 includes a sheet-like positive electrode 18 as a first electrode, a sheet-like negative electrode 19 as a second electrode, and a positive electrode 18 and a negative electrode 19. And a separator 20 that insulates them. The electrode assembly 12 has a layered structure with a separator 20 that insulates between the positive electrode 18 and the negative electrode 19 interposed. The electrode assembly 12 has a layered structure in which a plurality of positive electrodes 18 and a plurality of negative electrodes 19 are alternately arranged. The separator 20 is made of a microporous film.

  As shown in FIGS. 3A and 3B, the positive electrode 18 includes a positive electrode metal foil (aluminum foil in this embodiment) 21 and a positive electrode active material layer formed by applying a positive electrode active material on both surfaces thereof. 22a and 22b. Moreover, the positive electrode 18 has the uncoated part 23 which has not apply | coated the active material for positive electrodes. A positive electrode tab 24 as a first current collecting tab made of the positive electrode metal foil 21 is provided so as to protrude from the edge portion 18 a which is one side of the positive electrode 18. The positive electrode tab 24 is a part of the uncoated part 23. The positive electrode tab 24 serves as a positive electrode current collector that is electrically connected to the positive electrode terminal 15. The positive electrode tab 24 is formed in the same shape at the same position in each positive electrode 18 constituting the electrode assembly 12. The positive electrode 18 of the present embodiment is formed in a rectangular shape in which the region excluding the positive electrode tab 24 forms a rectangle when the positive electrode 18 is viewed from the front as shown in FIG.

  As shown in FIG. 3A, the positive electrode tab 24 has a virtual electrode center line extending along the tab protruding direction X1 through the center in the sheet width direction Y1 of the positive electrode 18 perpendicular to the tab protruding direction X1 of the positive electrode tab 24. Are arranged on the positive virtual center line L1. Further, when the tab width direction along the sheet width direction Y1 of the positive electrode 18 is “W1”, the positive tab 24 is a positive tab virtual center line L2 extending along the tab protruding direction X1 at the center of the tab width direction W1. Are arranged so as to coincide with the positive virtual center line L1. The positive virtual center line L1 is a virtual center line passing through the center of the positive electrode 18 in the sheet width direction Y1 and the center of the positive electrode tab 24 in the tab width direction W1. Thus, the positive electrode tab 24 is provided at a position where the positive electrode virtual center line L1 passes. In addition, as shown to Fig.3 (a), as for the positive electrode 18, the direction along the tab protrusion direction X1 turns into the sheet | seat height direction Z1.

  On the other hand, as shown in FIGS. 4A and 4B, the negative electrode 19 includes a negative electrode metal foil (copper foil in the present embodiment) 25 and a negative electrode active material obtained by applying a negative electrode active material on both surfaces thereof. It has material layers 26a and 26b. Further, the negative electrode 19 has an uncoated portion 27 to which no negative electrode active material is applied. A negative electrode tab 28 as a second current collecting tab made of the negative electrode metal foil 25 is provided so as to protrude from the edge portion 19 a which is one side of the negative electrode 19. The negative electrode tab 28 is a part of the uncoated portion 27. Further, the negative electrode tab 28 serves as a negative electrode current collector that is electrically connected to the negative electrode terminal 16. The negative electrode tab 28 is formed in the same position and in the same shape in each negative electrode 19 constituting the electrode assembly 12. In the negative electrode 19 of the present embodiment, the region excluding the negative electrode tab 28 is formed in a rectangular shape that forms a rectangle when the negative electrode 19 is viewed from the front as shown in FIG.

  As shown in FIG. 4A, the negative electrode tab 28 has a negative virtual center line extending along the tab protruding direction X2 through the center in the sheet width direction Y2 of the negative electrode 19 perpendicular to the tab protruding direction X2 of the negative electrode tab 28. It is not arranged on L3. That is, when the tab width direction along the sheet width direction Y2 of the negative electrode 19 is defined as “W2”, the negative tab 28 has a negative tab virtual center line L4 extending along the tab protruding direction X2 at the center of the tab width direction W2. And the negative virtual center line L3 are arranged so as not to coincide with each other. Further, in the negative electrode tab 28, the separation distance R along the sheet width direction Y2 between the negative electrode virtual center line L3 and the negative tab virtual center line L4 is larger than one half of the length along the tab width direction W2. Are arranged as follows. Thereby, the negative electrode tab 28 is not provided in the position where the negative electrode virtual center line L3 passes. Further, as shown in FIG. 1, the negative electrode tab 28 is provided at a position where it does not overlap with the positive electrode tab 24 when the positive electrode 18 and the negative electrode 19 are layered. In addition, as shown to Fig.4 (a), as for the negative electrode 19, the direction along the tab protrusion direction X2 turns into the sheet | seat height direction Z2.

  In the present embodiment, the positive electrode 18 has both the sheet width direction Y1 and the sheet height direction Z1 shown in FIG. 3A, and the negative electrode electrode 19 shown in FIG. It is formed smaller than both lengths in the length direction Z2. The sheet width direction Y <b> 1 and the sheet width direction Y <b> 2 are directions along a plane direction orthogonal to the stacking direction of the positive electrode 18 and the negative electrode 19.

  In the positive electrode 18, positive electrode active material layers 22a and 22b are formed in a region defined by the sheet width direction Y1 and the sheet height direction Z1. Similarly, negative electrode active material layers 26a and 26b are formed in the negative electrode 19 in a region defined by the sheet width direction Y2 and the sheet height direction Z2. When comparing the regions of the positive electrode active material layers 22a and 22b of the positive electrode 18 and the regions of the negative electrode active material layers 26a and 26b of the negative electrode 19, the regions of the negative electrode active material layers 26a and 26b are larger. . That is, the application area of the negative electrode active material in the negative electrode 19 is larger than the application area of the positive electrode active material in the positive electrode 18. In other words, the application area of the positive electrode active material in the positive electrode 18 is smaller than the application area of the negative electrode active material in the negative electrode 19. In the electrode assembly 12, a region where the positive electrode active material layers 22 a and 22 b of the positive electrode 18 and the negative electrode active material layers 26 a and 26 b of the negative electrode 19 overlap in the stacking direction H is an active region shown in FIGS. 1 and 2. It becomes the opposing part 29 of a material layer. The facing part 29 is a part that contributes to the chemical reaction of the battery. In addition, the positive electrode active material layer 22a and the positive electrode active material layer 22b in the positive electrode 18 are formed in a region having the same size. Moreover, the negative electrode active material layer 26a and the negative electrode active material layer 26b in the negative electrode 19 are formed in the same size region.

Hereinafter, the configuration of the electrode assembly 12 of this embodiment will be described in more detail.
As shown in FIG. 2, the electrode assembly 12 of this embodiment includes a positive electrode sheet body as an electrode sheet body having a laminated structure in which one or more positive electrode electrodes 18 are sandwiched between sheet-like separators 20 and folded in a zigzag manner. 30. The separator 20 includes a first separator 20a and a second separator 20b. As shown in FIGS. 5A and 5B, each positive electrode 18 constituting the positive electrode sheet body 30 has a positive electrode active material layer 22a, 22b on both sides paired with the first separator 20a and the second separator 20a. Covered by the separator 20b. As shown in FIG. 2, the positive electrode sheet 30 folded in a zigzag manner is provided with a plurality of linear portions 30 a and a plurality of bent portions 30 b alternately according to the number of folding. That is, as shown in FIG. 2, the positive electrode sheet 30 has a straight portion 30a connected to the first end K1 of the separator 20, and a bent portion 30b connected to the straight portion 30a. The straight portion 30a and the bent portion 30b are alternately generated and folded so that the next straight portion 30a is connected to the portion 30b. The positive electrode sheet 30 folded in this way becomes a zigzag shape or a meandering shape as a whole by the bent portion 30b. In addition, the separator 20 which comprises the positive electrode sheet body 30 is a continuous sheet | seat without a cut | interruption.

  In the electrode assembly 12, the negative electrode 19 is interposed between a pair of straight portions 30 a connected to one bent portion 30 b in the positive electrode sheet 30 that is folded in a zigzag manner. Thereby, the positive electrode 18 packaged in the positive electrode sheet body 30 and the negative electrode 19 interposed between the pair of straight portions 30a face each other. That is, in the electrode assembly 12, the facing portion 29 is disposed in the straight portion 30 a where the positive electrode active material layers 22 a and 22 b of the positive electrode 18 and the negative electrode active material layers 26 a and 26 b of the negative electrode 19 face each other. The electrode assembly 12 has a layered structure in which the positive electrode sheet 18 and the negative electrode 19 are alternately arranged by the positive electrode sheet 30 and the negative electrode 19. That is, the secondary battery 10 of the present embodiment includes the stacked electrode assembly 12 having a zigzag folded structure.

  As shown in FIG. 2, the length of each linear portion 30a orthogonal to the stacking direction H of the electrode assembly 12 is the length of the positive electrode 18 in the sheet width direction Y1 and the length of the negative electrode 19 in the sheet width direction Y2. It is longer than the length. Moreover, the electrode assembly 12 of this embodiment is provided with the negative electrode 19 in each of the outermost layers in the stacking direction H as shown in FIG. As a result, the positive electrode 18 disposed on the outermost side of the positive electrode sheet 30 faces the negative electrode 19 of the outermost layer. As shown in FIG. 2, the positive electrode 18 disposed on the outermost side in the positive electrode sheet body 30 includes the positive electrode 18 existing in the straight portion 30 a connected to the first end K <b> 1 of the positive electrode sheet 30, and the positive electrode This is the positive electrode 18 present in the straight line portion 30 a provided continuously with the second end K <b> 2 of the sheet body 30.

  And in the electrode assembly 12 of this embodiment, the positive electrode tab 24 is provided in the positive electrode 18 so that the positive electrode virtual center line L1 and the positive tab virtual center line L2 may correspond. For this reason, a positive electrode tab is provided in the position which passes along the virtual center line F shown in FIG. The virtual center line F passes through the center of the bent portions 30b arranged on both sides of the straight portion 30a, and extends along the direction in which these bent portions 30b extend (the direction of the arrow marked with “M” in FIG. 1). Is a line. As shown in FIG. 1, the direction in which the bent portion 30 b extends is perpendicular to the stacking direction H and is along the sheet height direction Z <b> 1 of the positive electrode 18 and the sheet height direction Z <b> 2 of the negative electrode 19.

  Moreover, in the electrode assembly 12 of this embodiment, as shown in FIG. 1, the edge part 18a of the positive electrode 18 provided with the positive electrode tab 24 is along the linear part 30a orthogonal to the direction where the bending part 30b extends. Similarly, in the electrode assembly 12 of the present embodiment, the edge portion 19a of the negative electrode 19 provided with the negative electrode tab 28 is along the straight portion 30a orthogonal to the extending direction of the bent portion 30b. Further, in the present embodiment, the positive electrode tab 24 and the negative electrode tab 28 protrude in the same direction, and the edge 18a of the positive electrode 18 provided with the positive electrode tab 24 and the edge 19a of the negative electrode provided with the negative electrode tab 28 are the same. Located on the side.

Hereinafter, the concept of folding in a zigzag manner will be described with reference to FIGS. 5 and 6.
As shown in FIG. 5A, first, a plurality of positive electrodes 18 are arranged at predetermined intervals on the first separator 20a. Each positive electrode 18 is arranged so that each positive electrode tab 24 faces the same direction. A dashed line shown in FIG. 5A indicates a fold line J when folded, and the bent portion 30b is formed by folding along the fold line J. In addition, when folding in a zigzag shape, the positive electrode sheet 30 is repeatedly folded along the fold line J between valley folds and mountain folds. The extending direction of the bent portion 30b is also a direction along the fold line J.

  In the present embodiment, the positive electrode 18 is connected to the virtual center line F1 defined between the bent portions 30b formed by folding along the fold line J, as shown in FIG. And the positive tab virtual center line L2 are arranged to coincide with each other. The positive virtual center line L1 is also a line that passes through the center of the edge 18a of the positive electrode 18 and extends in the direction in which the bent portion 30b extends.

  As shown in FIG. 5A, the positive electrode 18 arranged at the position closest to the first end K1 of the separator 20 is a fold line adjacent to the first end K1 and the first end K1. Arranged at the center between the bent portions 30b formed by folding at J. Although not shown in FIG. 5 (a), the positive electrode 18 disposed at the position closest to the second end K2 of the separator 20 also includes the second end K2 and the second end K2. It arrange | positions in the center between the bending parts 30b formed by folding in the adjacent folding line J. FIG. These positive electrodes 18 are also arranged in a state where the positive virtual center line L1 and the positive tab virtual center line L2 coincide with the virtual center line F.

  Then, as shown in FIGS. 5A and 5B, both surfaces of the positive electrode 18 arranged as described above are covered with the first separator 20a and the second separator 20b. In addition, the 1st separator 20a and the 2nd separator 20b are joined by the junction part S, as shown in FIG.5 (b). The joint portion S is formed around the positive electrode 18 except for the positive electrode tab 24 side. The joint S along the sheet width direction Y1 of the positive electrode 18 is located on the fold line J. And the junction part S is formed by welding, for example. Thereby, the positive electrode sheet body 30 which covered the positive electrode 18 with a pair of 1st separator 20a and 2nd separator 20b is completed. Further, in the completed positive electrode sheet body 30, the arrangement area of each positive electrode 18 is partitioned by the joint portion S. The joining portion S is illustrated only in FIGS. 5B and 5C.

  And the electrode assembly 12 is produced using the positive electrode sheet body 30 and the negative electrode 19 which were comprised as mentioned above. That is, the electrode assembly 12 is created by repeatedly folding the positive electrode sheet body 30 and disposing the negative electrode 19 at a position opposite to the positive electrode 18.

  FIG. 5C shows a state in which the negative electrode 19 is disposed at a position facing the positive electrode 18. The negative electrode 19 is disposed so that the negative electrode tab 28 faces the same direction as the positive electrode tab 24 of the positive electrode 18. The negative electrodes 19 are arranged so that the negative electrode tabs 28 of all the negative electrodes 19 face in the same direction and overlap in the stacking direction H of the positive electrodes 18 and 19.

  FIG. 6A shows a state where the positive electrode sheet 30 is folded. FIG. 6B shows a state in which the negative electrode 19 is sandwiched between the positive electrode sheets 30 by folding the positive electrode sheets 30. Thus, the negative electrode 19 is interposed between the straight portions 30 a by folding the positive electrode sheet 30. When the positive electrode sheet 30 is folded, the two adjacent positive electrodes 18 face each other with the negative electrode 19 in between and overlap in the stacking direction H. That is, the adjacent positive electrodes 18x and 18y denoted by [18x] and [18y] in FIG. 6A are opposed to each other with the negative electrode 19 interposed therebetween, and overlap in the stacking direction H.

  The positive electrode 18 of this embodiment is arrange | positioned in the state in which the positive virtual center line L1 and the positive tab virtual center line L2 corresponded with the virtual center line F, as demonstrated using Fig.3 (a). For this reason, as shown in FIG. 6B, when the positive electrode sheet body 30 is folded, if the positive electrode sheet body 30 is arranged at the center of the bent portion 30b, the positive electrode tabs 24 of the positive electrode 18x and the positive electrode 18y. Will overlap in the stacking direction H of the positive electrode 18 and the negative electrode 19. That is, the positive electrode tab 24 of each positive electrode 18 overlaps in the stacking direction H without being significantly displaced along the sheet width direction Y1 of the positive electrode 18.

  FIG. 6C shows a state in which the negative electrode 19 is further arranged at a position facing the positive electrode 18 from the state of FIG. Then, the positive electrode sheet 30 is subsequently folded in the same manner as in FIGS. In addition, the folding direction of the positive electrode sheet body 30 folded in a zigzag manner, that is, the mountain fold and the valley fold change alternately.

  When the positive electrode sheet 30 is folded as described above, the electrode assembly 12 is produced as shown in FIG. That is, the positive electrode tab 24 of each positive electrode 18 constituting the electrode assembly 12 overlaps in the stacking direction H. Further, the negative electrode tab 28 of each negative electrode 19 constituting the electrode assembly 12 protrudes in the same direction as the positive electrode tab 24 of the positive electrode 18 and overlaps the stacking direction H at a position where it does not overlap the positive electrode tab 24.

Hereinafter, the operation of the present embodiment will be described.
When the positive electrode sheet 30 is folded in a zigzag manner, the positive electrodes 18x and 18y before the positive electrode sheet 30 are all folded in the same direction in the adjacent positive electrodes 18x and 18y. The direction will be reversed. For example, in the state of FIG. 5A, the positive electrode active material layer 22a faces upward in the positive electrodes 18x and 18y. When the positive electrode sheet 30 is folded in this state, the positive electrode active material layers 22a of the positive electrodes 18x and 18y face each other so that the positive electrode active material layer 22b of the positive electrode 18y faces upward and the direction of the positive electrode 18y is reversed. Will do.

  For this reason, when the positive electrode 18 is arranged in the same posture at the time of manufacturing the positive electrode sheet 30, for example, when the positive electrode tab 24 is provided at a position where the positive virtual center line L1 does not pass, the positive electrode tab 24 is laminated when folded. Does not overlap in direction H. However, in the positive electrode 18 of the present embodiment, the positive electrode tab 24 is provided at a position where the positive virtual center line L1 passes, and the positive virtual center line L1 of the positive electrodes 18x and 18y overlaps the virtual center line F. Even if the positive electrode 18 is arranged in the same posture when the positive electrode sheet 30 is manufactured, the positive electrode tab 24 overlaps in the stacking direction H when folded.

  For example, it is assumed that the position of the positive electrode tab 24 of the positive electrode 18 is the same as that of the negative electrode tab 28 of the negative electrode 19 of this embodiment. In this case, when the positive electrode 18 is disposed in the same posture, the positive electrode tab 24 does not overlap in the stacking direction H because the positive electrode tab 24 is provided at a position where the positive electrode virtual center line L1 does not pass. That is, the positive electrode tabs 24 of the adjacent positive electrode 18 are spaced apart along the sheet width direction Y1 of the positive electrode 18. Therefore, by providing the positive electrode tab 24 of the positive electrode 18 at a position where the positive virtual center line L1 passes as in the present embodiment, the positive electrode 18 is disposed without considering the folded state of the positive electrode sheet body 30. The positive electrode sheet 30 can be easily manufactured. That is, the production of the electrode assembly 12 is facilitated.

Therefore, in this embodiment, the following effects can be obtained.
(1) The positive electrode tab 24 of the positive electrode 18 is formed at a position where the positive virtual center line L1 passes. For this reason, when the positive electrode sheet 30 is folded in a zigzag shape, the positive electrode tab 24 of the positive electrode 18 is disposed at a position through which the virtual center line F passes. That is, the positive electrode tab 24 of each positive electrode 18 overlaps in the stacking direction H of the electrode assembly 12 at a position where the virtual center line F passes. Therefore, the positive electrode sheet 30 can be easily manufactured without arranging the positive electrode 18 in consideration of the folded state. In other words, the manufacturing efficiency of the electrode assembly 12 can be improved. As a result, the manufacturing efficiency of the secondary battery 10 can be improved.

  (2) Further, the negative electrode tab 28 of the negative electrode 19 was formed at a position in the electrode assembly 12 so as not to overlap the positive electrode tab 24 of the positive electrode 18. For this reason, a short circuit between the positive electrode 18 and the negative electrode 19 is suppressed.

  (3) Since the negative electrode 19 is interposed between the straight portions 30a of the positive electrode sheet 30 so that the negative electrode tabs 28 overlap, the efficiency of manufacturing the electrode assembly 12 can be improved. That is, when the electrode assembly 12 is manufactured, the positive electrode tabs 24 and the negative electrode tabs 28 can be overlapped with each other, so that the manufacturing efficiency of the electrode assembly 12 can be improved.

  (4) Since the positive electrode 18 constituting the positive electrode sheet 30 is in a discontinuous sheet shape, the positive electrode 18 can be easily manufactured. Moreover, when manufacturing the positive electrode sheet body 30, the positive electrode 18 can be arrange | positioned easily.

  (5) Since the positive electrode 18 is disposed so that the center of the positive electrode tab 24 coincides with the positive virtual center line L1, the positive electrode tab 24 of each positive electrode 18 is securely disposed at the position where the virtual center line F passes. They can be overlapped in the stacking direction H of the assembly 12. Therefore, the positive electrode sheet 30 can be easily manufactured without arranging the positive electrode 18 in consideration of the folded state. In other words, the manufacturing efficiency of the electrode assembly 12 can be improved.

  (6) The positive electrode sheet 30 is formed by the separator 20 and the positive electrode 18, and the positive electrode sheet 18 can be easily positioned by folding the positive electrode sheet 30 into a folded shape.

  (7) In the electrode assembly 12, the positive electrode tab 24 of the positive electrode 18 and the negative electrode tab 28 of the negative electrode 19 are projected in the same direction. Miniaturization can be achieved.

  (8) Further, since the positive electrode tab 24 is not formed in the entire region of the edge portion 18a of the positive electrode 18, but is formed in a part thereof, the positive electrode 18 and the negative electrode 19 are layered. However, the negative electrode tab 28 can protrude in the same direction as the positive electrode tab 24. Therefore, the effect (7) can be achieved.

In addition, you may change this embodiment as follows.
As shown in FIG. 7, you may form the positive electrode 18 in the case of comprising the positive electrode sheet body 30 in strip shape. In this case, a plurality of positive electrode tabs 24 are formed on the positive electrode 18 at predetermined intervals along the direction in which the positive electrode 18 extends in a strip shape. And the space | interval of the positive electrode tabs 24 is made into the space | interval which each positive electrode tab 24 is located in the position where the virtual center line F passes similarly to embodiment. In addition, when making the positive electrode 18 into strip | belt shape, in the bending part 30b formed when the positive electrode sheet body 30 is folded, the negative electrode which opposes the positive electrode which exists in the said bending part 30b does not exist. For this reason, in order to suppress the ion movement from a positive electrode, you may affix an adhesive tape etc. to the bending part 30b, for example.

  The positive electrode tab 24 of the positive electrode 18 only needs to be provided at a position where the positive virtual center line L1 passes, and the positive virtual center line L1 and the positive tab virtual center line L2 do not coincide with each other as in the embodiment. Also good. FIG. 8 shows an example of the positive electrode 18 of this another example. In the positive electrode 18 of FIG. 8, the positive electrode tab 24 is provided at a position where the positive electrode virtual center line L1 and the positive tab virtual center line L2 do not coincide. On the other hand, the positive electrode tab 24 of the positive electrode 18 in FIG. 8 is provided at a position where the positive virtual center line L1 passes. When the positive electrode sheet 30 using such a positive electrode 18 is folded, the positive electrode tab 24 of each positive electrode 18 has a reduced area where each positive electrode tab 24 overlaps in the stacking direction H compared to the embodiment. It overlaps in the area | region shown with the oblique line in FIG. Note that the two-dot chain line in FIG. 8 indicates the position of the positive electrode tab 24 of the adjacent positive electrode 18. In other words, the overlapping of the positive electrode tabs 24 can be achieved by providing the positive electrode tabs 24 at positions where the positive electrode virtual center line L1 passes. Therefore, even in the case of the positive electrode 18 according to this different example, the positive electrode sheet 18 can be efficiently manufactured without arranging the positive electrode 18 in consideration of the folded state. In other words, the manufacturing efficiency of the electrode assembly 12 can be improved.

  (Circle) the separator 20 which comprises the positive electrode sheet body 30 is good also as one sheet. That is, a separator 20 having a size capable of covering both surfaces of the positive electrode 18 may be prepared, and both surfaces of the positive electrode 18 may be covered by bending the separator 20. By using such a separator 20, the area of the joint S can be reduced.

  The positive electrode 18 may not be arranged so that the positive virtual center line L1 and the positive tab virtual center line L2 completely coincide with the virtual center line F. The positive virtual center line L1 and the positive tab virtual center line L2 May be arranged so as to substantially coincide with the virtual center line F. That is, the positive electrode 18 may be arranged so that the virtual center line F passes through the positive electrode tab 24.

  In the embodiment, the positive electrode sheet 30 is formed by the positive electrode 18 and the separator 20, but the negative electrode sheet may be formed by the negative electrode 19 and the separator 20. That is, the negative electrode sheet body may be folded in a zigzag manner, and the positive electrode 18 may be interposed between the straight portions of the negative electrode sheet body. In this case, the negative electrode tab 28 of the negative electrode 19 is provided at the same position as the positive electrode tab 24 of the positive electrode 18 described in the embodiment. On the other hand, the positive electrode tab 24 of the positive electrode 18 is provided at the same position as the negative electrode tab 28 of the negative electrode 19 described in the embodiment. Even if it is a negative electrode like this another example, manufacture of a negative electrode sheet body becomes easy, without arrange | positioning the negative electrode 19 in consideration of the state of folding. In other words, the manufacturing efficiency of the electrode assembly 12 can be improved. In addition, the change of the positive electrode and the negative electrode in this separate example is not limited to the embodiment, and can be applied to each separate example described above.

  The positive electrode 18 may be formed by applying an active material on one side to form a positive electrode active material layer. Similarly, the negative electrode 19 may have a negative electrode active material layer formed by applying an active material on one side. In this case, the positive electrode active material layer of the positive electrode 18 and the negative electrode active material layer of the negative electrode 19 are arranged so as to face each other.

O The joining of the first separator 20a and the second separator 20b may be changed to adhesion or locking instead of welding.
The separator 20 may be a separator coated with ceramic.

In the embodiment, the shapes of the positive electrode 18 and the negative electrode 19 may be changed. For example, it may be formed in a square in front view.
The secondary battery 10 of the embodiment is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

(Circle) the secondary battery 10 of embodiment may be mounted in a motor vehicle as a vehicle, and may be mounted in an industrial vehicle. Further, the present invention may be applied to a stationary power storage device.
○ The connection mode between the positive electrode tab 24 (positive electrode current collector) and the positive electrode terminal 15 and the connection mode between the negative electrode tab 28 (negative electrode current collector) and the negative electrode terminal 16 are not limited to the configuration of the embodiment, and may be arbitrarily changed. Also good.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery, 12 ... Electrode assembly, 18 ... Positive electrode, 18a ... Edge, 19 ... Negative electrode, 19a ... Edge, 20 ... Separator, 20a ... First separator, 20b ... Second separator, 21 ... Metal foil for positive electrode, 22a, 22b ... Positive electrode active material layer, 23 ... Uncoated part, 24 ... Positive electrode tab, 25 ... Metal foil for negative electrode, 26a, 26b ... Negative electrode active material layer, 27 ... Uncoated part, 28 DESCRIPTION OF SYMBOLS ... Negative electrode tab, 30 ... Positive electrode sheet body, 30a ... Straight part, 30b ... Bending part, L1 ... Positive electrode virtual center line, F ... Virtual center line, H ... Stacking direction, S ... Joining part.

Claims (7)

One or more first electrodes are sandwiched between sheet-shaped separators, and an electrode sheet body having a laminated structure in which bent portions and straight portions are alternately provided, and between adjacent straight portions in the electrode sheet body An electrode assembly having a plurality of second electrodes each having a polarity different from that of the first electrode interposed between the first electrode and the second electrode,
A case for housing the electrode assembly;
A first electrode terminal fixed to the case and electrically connected to the first electrode;
A second electrode terminal fixed to the case and electrically connected to the second electrode,
The first electrode is provided with a first current-collecting tab that protrudes from one side of the first electrode that is orthogonal to the direction in which the bent portion extends and that extends along the straight line portion. And
The second electrode is provided with a projecting second current collecting tab electrically connected to the second electrode terminal on one side of the first electrode on the same side as the one side,
When defining a virtual center line passing through the center between the bent portions arranged on both sides of the straight portion and extending along the direction in which the bent portion extends,
The first current collecting tab is provided at a position through which the virtual center line passes,
The second current collecting tab is provided at a position where at least a part of the second current collecting tabs provided on each second electrode overlaps with each other in the stacking direction but does not overlap with the first current collecting tab in the stacking direction. A power storage device. The electrode sheet body has a plurality of first electrodes,
The power storage device according to claim 1, wherein each first electrode is disposed in the straight line portion.   The first electrode is a virtual electrode in which a center of the first current collecting tab in a direction orthogonal to a direction in which the bent portion extends extends along a direction in which the bent portion extends through the center of the one side of the first electrode. The power storage device according to claim 2, wherein the power storage device is disposed at a position that coincides with the center line.   4. The power storage device according to claim 2, wherein the electrode sheet body includes a joint that joins separators sandwiching the first electrode around the first electrode. 5. The first electrode is a positive electrode;
The power storage device according to any one of claims 1 to 4, wherein the second electrode is a negative electrode.   The power storage device according to any one of claims 1 to 5, wherein the power storage device is a secondary battery. One or more first electrodes are sandwiched between sheet-shaped separators, and an electrode sheet body having a laminated structure in which bent portions and straight portions are alternately provided, and between adjacent straight portions in the electrode sheet body A method of manufacturing an electrode assembly having a plurality of second electrodes having different polarities from the first electrode interposed in each of the first electrodes,
The first electrode is electrically connected to a first electrode terminal fixed to a case that accommodates the electrode assembly, and the first electrode is orthogonal to a direction in which the bent portion extends and is connected to the linear portion. A first current collecting tab that is electrically connected to the first electrode terminal protrudes from one side of the first electrode along the first electrode;
The second electrode is electrically connected to a second electrode terminal fixed to the case, and the second electrode is electrically connected to the second electrode terminal on one side of the first electrode on the same side as the one side. A second current collecting tab to be connected in a protruding manner,
When defining a virtual center line passing through the center between the bent portions arranged on both sides of the straight portion and extending along the direction in which the bent portion extends,
The first current collecting tab is provided at a position through which the virtual center line passes,
The second current collecting tab is provided at a position where at least a part of the second current collecting tabs provided on each second electrode overlaps with each other in the stacking direction but does not overlap with the first current collecting tab in the stacking direction. And
The electrode sheet is formed by sandwiching the first electrode between the separators, the electrode sheet is folded in a zigzag manner, and the second electrode is interposed between linear portions of the electrode sheet. A method of manufacturing an electrode assembly in which electrodes and the second electrode are alternately arranged to form a layer.