JP2016178028A - Electrode body and power storage element having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrode body in which wrinkles are less likely to occur in positive and negative electrodes when charging and discharging are repeated.SOLUTION: An electrode body 2 has a winding core 21 constructed by winding a strip-like sheet 210 in a flat cylindrical shape. A portion extending from a second end 210b of the sheet 210 of the electrode body 2, and a portion extending from the starting end 240 of one electrode plate of the positive electrode 23 and negative electrode 24 are arranged in the circumferential direction of the winding core 21, whereby variation in the number of stacked layers in the Y-axis direction at respective positions in the Z axis direction is suppressed. Accordingly, the number of the stepped portions occurring between the adjacent portions in the Z axis direction on the winding surface due to the difference in the number of stacked layers can be suppressed.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an electrode body including a positive electrode and a negative electrode, and a power storage device including the electrode body.

  Conventionally, a flat wound secondary battery (hereinafter simply referred to as “secondary battery”) including a wound electrode body having a positive electrode and a negative electrode, and a battery container that houses the wound electrode body. Provided (see, for example, Patent Document 1). This wound electrode body has both a winding core and a separator.

  The winding core is formed by winding a resin sheet into a flat cylindrical shape. The wound electrode body is formed by winding the positive electrode and the negative electrode, which are overlapped so that the separator is interposed, around a winding core.

  In the wound electrode body, a winding start end portion of the resin sheet constituting the winding core, a winding end end portion of the resin sheet, a winding start end portion of the positive electrode, and a winding start end portion of the negative electrode Depending on the arrangement position in the rotation direction, on the winding surface during winding of the positive electrode and the negative electrode (the outer peripheral surface in the laminate of the positive electrode and the negative electrode while the positive electrode and the negative electrode are wound) In some cases, a large step portion was generated.

  When such a step portion occurs, in the completed wound electrode body (that is, finished winding the positive electrode and the negative electrode), between the winding core and the positive electrode or the negative electrode, A gap is generated between the positive electrode and the negative electrode. In this case, when the secondary battery is repeatedly charged and discharged, and the expansion and contraction of the positive electrode and the negative electrode are repeated, the positive electrode and the negative electrode are wrinkled at the position where the gap is generated. It is likely to occur.

JP 2013-232439 A

  Then, this invention makes it a subject to provide an electrode body which is hard to generate | occur | produce a wrinkle in a positive electrode and a negative electrode when charging / discharging is repeated in view of this situation, and an electrical storage element provided with this electrode body.

The electrode body according to the present invention comprises:
A winding core configured by winding a belt-like sheet into a flat cylindrical shape, wherein the first end in the longitudinal direction of the sheet is located on the inner peripheral surface and the first end in the longitudinal direction of the sheet A core whose second end opposite to the outer peripheral surface is located on the outer peripheral surface;
A belt-like positive electrode and a negative electrode wound in the same direction on the outer peripheral surface of the core in a state of being insulated from each other;
The first end and the second end are arranged at positions shifted from each other in the circumferential direction of the core,
Each of the positive electrode and the negative electrode has a starting end disposed directly or indirectly on the outer peripheral surface of the core,
Either the positive electrode or the negative electrode is disposed from the start end in a direction opposite to the extending direction of the sheet from the second end in a state where the start end is disposed adjacent to the second end in the circumferential direction. Extending or arranged so that the starting end is aligned with the second end in the flat direction of the core perpendicular to the thickness direction at a position shifted from the arrangement position of the second end in the thickness direction of the flat core In this state, the sheet extends from the starting end in a direction opposite to the extending direction of the sheet from the second end.

  According to such a configuration, the part extending from the second end of the sheet and the part extending from the starting end of the one electrode plate (positive electrode or negative electrode) are aligned in the circumferential direction of the core, or shifted from each other in the thickness direction. By aligning in the flat direction at a certain position, the portion extending from the starting end of the one electrode plate and the portion extending from the second end of the sheet overlap with each other in the thickness direction. Variation in the number of stacks in the thickness direction (the total number of stacks of sheets, positive electrodes, and negative electrodes in the thickness direction) can be suppressed. Thus, the stepped portion on the winding surface (the outer peripheral surface of the laminate 22 formed by the positive electrode and the negative electrode while the positive electrode and the negative electrode are wound) caused by the difference in the number of layers between the adjacent portions in the flat direction. As a result, it is possible to suppress the generation of wrinkles due to the stepped portion when charge and discharge are repeated.

In the electrode body,
The other electrode plate of the positive electrode or the negative electrode is arranged in a state where the start end is aligned with the first end in the flat direction at a position shifted from the arrangement position of the first end in the thickness direction. It is preferable that the first end extends from the start end in a direction opposite to the direction in which the sheet extends.

  Thus, the portion extending from the first end of the sheet and the portion extending from the starting end of the other electrode plate (negative electrode or positive electrode) are aligned in the flat direction at positions shifted from each other in the thickness direction, The number of stacked layers in the thickness direction at each position in the flat direction (the sheet in the thickness direction, the positive electrode) generated by overlapping the portion extending from the starting end of the other electrode plate and the portion extending from the first end of the sheet in the thickness direction. , And the total number of laminated negative electrodes) can be further suppressed. Thereby, it is possible to further suppress the number of stepped portions on the winding surface caused by the difference in the number of layers between the adjacent portions in the flat direction, and as a result, due to the stepped portions when charging and discharging are repeated. It is possible to more reliably suppress the occurrence of wrinkles.

The core is
A pair of curved portions facing each other with a gap in the flat direction;
A pair of straight portions facing each other at an interval in the thickness direction, and having a pair of straight portions connecting corresponding ends of the curved portion,
The first end and the second end may be disposed at a position corresponding to the straight line portion.

  According to such a configuration, the portion extending from the starting end of the positive electrode and the portion extending from the starting end of the negative electrode are arranged directly or indirectly on the straight line portion on the outer peripheral surface of the core, and thus extend from the respective starting ends. The positive electrode and the negative electrode are wound in a state where the portion is straight, and this causes a force to move away from the winding core at the start end of the positive electrode and the start end of the negative electrode (a force that the electrode plate arranged in a bent state tries to return straight) ) Is less likely to occur, and as a result, the starting end of the positive electrode and the starting end of the negative electrode are prevented from separating from the outer surface of the core.

In the electrode body,
Each of the difference in thickness between the sheet and the positive electrode, the difference in thickness between the positive electrode and the negative electrode, and the difference in thickness between the sheet and the negative electrode are preferably 60 μm or less.

  In this way, by suppressing the difference in thickness, it is possible to prevent the stepped portion due to the difference from occurring on the winding surface.

The electricity storage device according to the present invention is:
Any of the above electrode bodies;
A case for housing the electrode body;
An external terminal disposed outside the case and electrically connected to the electrode body.

  According to such a configuration, in the electrode body, the portion extending from the second end of the sheet and the portion extending from the starting end of the one electrode plate (positive electrode or negative electrode) are arranged in the circumferential direction of the core, or the thickness. By arranging in the flat direction at positions shifted from each other in the direction, variation in the number of stacks in the thickness direction at each position in the flat direction (the total number of stacks of sheets, positive electrodes, and negative electrodes in the thickness direction) is suppressed, Thereby, the number of level | step-difference parts in the winding surface produced by the difference in the number of lamination | stacking between the site | parts adjacent to the said flat direction is suppressed. As a result, even if the positive electrode and the negative electrode are repeatedly expanded and contracted due to charge and discharge, generation of wrinkles in the positive electrode and the negative electrode can be suppressed.

  As described above, according to the present invention, it is possible to provide an electrode body in which wrinkles are unlikely to occur in the positive electrode and the negative electrode when charge and discharge are repeated, and a power storage device including the electrode body.

FIG. 1 is a perspective view of a power storage device according to this embodiment. FIG. 2 is a front view of the power storage element. 3 is a cross-sectional view taken along the line III-III in FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. FIG. 5 is an exploded view of the electricity storage element. FIG. 6 is a perspective view of a state in which a part of the power storage element is assembled, and is a perspective view of a state in which a liquid filling tap, an electrode body, a current collector, and a terminal portion are assembled to a lid plate. FIG. 7 is a diagram for explaining the configuration of the electrode body of the electricity storage element. FIG. 8 is a diagram illustrating a winding state of the positive electrode, the negative electrode, and the separator in the electrode body. FIG. 9 is a diagram for explaining a configuration of the electrode body. FIG. 10 is a diagram for explaining a method of manufacturing the electrode body. FIG. 11 is a diagram for explaining a method of manufacturing the electrode body. FIG. 12 is a view for explaining an electrode body according to another embodiment. FIG. 13 is a view for explaining an electrode body according to another embodiment. FIG. 14 is a perspective view of a power storage device including the power storage element according to this embodiment.

  Hereinafter, an embodiment of a power storage device according to the present invention will be described with reference to FIGS. 1 to 12. Examples of power storage elements include secondary batteries and capacitors. In the present embodiment, a chargeable / dischargeable secondary battery will be described as an example of a power storage element. In addition, the name of each structural member of this embodiment is in this embodiment, and may differ from the name of each structural member in background art.

  The electricity storage device of this embodiment is a nonaqueous electrolyte secondary battery. More specifically, the power storage element is a lithium ion secondary battery that utilizes electron transfer that occurs as lithium ions move. This type of power storage element supplies electrical energy. One or a plurality of power storage elements are used. Specifically, the storage element is used singly when the required output and the required voltage are small. On the other hand, when at least one of a required output and a required voltage is large, the power storage element is used in a power storage device in combination with another power storage element. In the power storage device, a power storage element used in the power storage device supplies electric energy.

  As shown in FIGS. 1 to 7, the power storage element includes an electrode body 2 including a positive electrode 23 and a negative electrode 24, a case 3 that houses the electrode body 2, and an external terminal 4 that is disposed outside the case 3. And an external terminal 4 electrically connected to the electrode body 2. In addition to the electrode body 2, the case 3, and the external terminal 4, the power storage element 1 includes a current collector 5 that electrically connects the electrode body 2 and the external terminal 4.

  As shown in FIGS. 3 to 9, the electrode body 2 includes a winding core 21, and a strip-like positive electrode 23 and a negative electrode 24 wound around the outer peripheral surface of the winding core 21 in the same direction while being insulated from each other. Prepare. As the lithium ions move between the positive electrode 23 and the negative electrode 24 in the electrode body 2, the storage element 1 (electrode body 2) is charged and discharged.

  The winding core 21 is usually formed of an insulating material. The winding core 21 is cylindrical. The core 21 of this embodiment is a flat cylinder shape. Specifically, the winding core 21 includes a pair of curved portions 211 facing each other with a gap therebetween and a pair of straight portions 212 facing each other with a gap therebetween. And a pair of linear portions 212 that connect end portions facing each other (see FIG. 4). Each bending portion 211 is bent so as to protrude outward (in a direction away from each other). The pair of straight portions 212 are parallel or substantially parallel. In the following, the direction in which the pair of curved portions 211 face each other may be referred to as the flat direction of the core 21, and the direction in which the pair of straight portions 212 face each other as the thickness direction of the core 21.

  The core 21 of the present embodiment is formed by winding a belt-like sheet 210 having flexibility or thermoplasticity into a flat cylindrical shape. In the core 21, as shown in FIG. 9, one end (first end) 210 a in the longitudinal direction of the sheet 210 is positioned on the inner peripheral surface of the core 21, and the other end (second) in the longitudinal direction of the sheet 210. (End: end opposite to the first end in the longitudinal direction) 210 b is located on the outer peripheral surface of the core 21. The first end 210a and the second end 210b are arranged at positions shifted from each other in the circumferential direction of the winding core 21 (winding direction of the sheet 210).

  The sheet 210 is formed of a synthetic resin. The sheet 210 has resistance to the electrolytic solution. The thickness of the sheet 210 is, for example, 50 μm to 200 μm. The thickness of the sheet 210 of this embodiment is 150 μm, for example. The material of the sheet 210 constituting the winding core 21 is not limited to a synthetic resin, and may be a metal such as aluminum or copper.

  As shown in FIG. 7, the laminate 22 is formed by being wound around the core 21 in a state where the positive electrode 23 and the negative electrode 24 are laminated (overlapped). As shown in FIGS. 8 and 9, each of the positive electrode 23 and the negative electrode 24 has start ends 230 and 240 arranged directly or indirectly on the outer peripheral surface of the core 21.

  The starting end 240 of the negative electrode 24 is disposed at a position adjacent to the second end 210b of the core 21 in the circumferential direction. The negative electrode 24 is wound so as to extend from the start end 230 in the direction opposite to the direction in which the sheet extends from the second end 210b. Further, the starting end 240 of the negative electrode 24 is disposed on the outer peripheral surface of a linear portion 212 (described later) of the core 21 (in the present embodiment, it is disposed on the outer surface of the linear portion 212 of the core 21 via the separator 25). ). In FIG. 9, a space is provided between the second end 210 b of the sheet 210 and the start end 240 of the negative electrode 24 for convenience.

  The negative electrode 24 has a metal foil and a negative electrode active material layer formed on the metal foil. The metal foil is strip-shaped. The metal foil of this embodiment is a copper foil, for example. The negative electrode 24 has a non-covered portion (a portion where the negative electrode active material layer is not formed) 241 of the negative electrode active material layer at one end edge in the width direction, which is the short side direction of the band shape.

  The starting end 230 of the positive electrode 23 is located at a position shifted from the arrangement position of the first end 210a in the thickness direction (Y-axis direction in FIG. 9) in the flat direction (Z-axis direction in FIG. 9). Are arranged side by side. The positive electrode 23 is wound so as to extend from the start end 240 in the direction opposite to the direction in which the sheet 210 extends from the first end 210a. Further, the starting end 230 of the positive electrode 23 is disposed on the outer peripheral surface of a linear portion 212 described later of the core 21 (in the present embodiment, on the outer surface of the linear portion 212 of the core 21 via the negative electrode 24 and the separator 25). Placed).

  The positive electrode 23 has a metal foil and a positive electrode active material layer formed on the metal foil. The metal foil is strip-shaped. The metal foil of this embodiment is an aluminum foil, for example. The positive electrode 23 has a non-covered portion (positive electrode active material layer) of the positive electrode active material layer formed on the other edge in the width direction which is the short side direction of the band shape (on the side opposite to the non-covered portion 231 of the positive electrode 23). (Part not) 231. A portion of the positive electrode 23 where the positive electrode active material layer is formed is referred to as a covering portion 232. The width of the covering portion (portion where the positive electrode active material layer is formed) 232 of the positive electrode 23 is smaller than the width of the covering portion 242 of the negative electrode 24.

  In addition, it is preferable that the difference of each thickness of the above positive electrode 23 and the negative electrode 24, and the sheet | seat 210 is 60 micrometers or less. As described above, since the thickness of the sheet 210 of the present embodiment is 150 μm, the thickness of the positive electrode 23 is preferably 139 μm to 155 μm, and the thickness of the negative electrode 24 is preferably 120 μm to 128 μm.

  In the electrode body 2 of the present embodiment, the positive electrode 23 and the negative electrode 24 configured as described above are wound in a state where they are insulated by the separator 25. That is, in the electrode body 2 of the present embodiment, the laminated body 22 of the positive electrode 23, the negative electrode 24, and the separator 25 is wound.

  The separator 25 is a strip-shaped member having insulating properties. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24. Thereby, in the electrode body 2 (specifically, the laminated body 22), the positive electrode 23 and the negative electrode 24 are insulated from each other. The separator 25 holds the electrolytic solution in the case 3. Thereby, at the time of charging / discharging of the electrical storage element 1, lithium ion moves between the positive electrode 23 and the negative electrode 24 which are laminated | stacked alternately on both sides of the separator 25. FIG.

  The thickness of the separator 25 is 12 μm to 30 μm. The width of the separator (the dimension of the strip shape in the short direction) is slightly larger than the width of the covering portion 242 of the negative electrode 24. The separator 25 is disposed between the positive electrode 23 and the negative electrode 24 that are overlapped in a state where the separators 232 and 242 are displaced in the width direction so as to overlap each other. At this time, the non-covered portion 231 of the positive electrode 23 and the non-covered portion 241 of the negative electrode 24 do not overlap. That is, the non-covered portion 231 of the positive electrode 23 protrudes in the width direction from the region where the positive electrode 23 and the negative electrode 24 overlap, and the non-covered portion 241 of the negative electrode 24 extends from the region where the positive electrode 23 and the negative electrode 24 overlap in the width direction ( It protrudes in a direction opposite to the protruding direction of the non-covered portion 231 of the positive electrode 23. The electrode body 2 is formed by winding the stacked positive electrode 23, negative electrode 24, and separator 25, that is, the stacked body 22. The portion where only the uncovered portion 231 of the positive electrode 23 or the uncovered portion 241 of the negative electrode 24 is stacked constitutes the uncovered stacked portion 26 in the electrode body 2.

  The uncoated laminated portion 26 is provided at each electrode of the electrode body 2. That is, the non-coated laminated portion 26 in which only the non-coated portion 231 of the positive electrode 23 is laminated constitutes the non-coated laminated portion of the positive electrode in the electrode body 2, and the non-coated laminated portion in which only the non-coated portion 241 of the negative electrode 24 is laminated. 26 constitutes an uncoated laminated portion of the negative electrode in the electrode body 2.

  The case 3 includes a case main body 31 having an opening and a cover plate 32 that closes (closes) the opening of the case main body 31. The case 3 houses the electrolytic solution in the internal space 33 together with the electrode body 2 and the current collector 5. The case main body 31 of the present embodiment has a flat bottomed rectangular tube shape.

  The case 3 is formed by joining the opening peripheral edge 34 of the case main body 31 and the peripheral edge of the cover plate 32 in an overlapped state. The case 3 has an internal space 33 defined by the case main body 31 and the lid plate 32. The opening peripheral edge 34 of the case 3 is a pair of long sides that are parallel to each other, and is connected to each of a pair of long sides that are long in one direction and opposite ends of the pair of long sides. With a short side. In this embodiment, the opening peripheral part 34 of the case main body 31 and the peripheral part of the cover plate 32 are welded.

  In the following, as shown in FIG. 1, the direction in which the long side of the opening peripheral edge 34 of the case 3 extends is the X-axis direction, and the direction in which the short side of the opening peripheral edge 34 of the case 3 extends is the Y-axis direction (core 21 The direction perpendicular to the X-axis direction and the Y-axis direction is taken as the Z-axis direction (flat direction of the core 21).

  The external terminal 4 is a part that is electrically connected to an external terminal of another power storage element or an external device. The external terminal 4 is formed of a conductive member.

  The current collector 5 is disposed in the case 3 and connects the electrode body 2 and the external terminal 4. The current collector 5 is disposed on each of the positive electrode and the negative electrode of the power storage device 1. Each current collector 5 is connected to the positive electrode uncoated laminated portion 26 and the negative electrode uncoated laminated portion 26 of the electrode body 2 in the case 3.

  The power storage device 1 also includes an insulating member 6 that insulates the electrode body 2 from the case 3. The insulating member 6 of this embodiment is an insulating cover, for example. As shown in FIGS. 3 to 5, the insulating cover 6 is disposed between the case 3 (specifically, the case main body 31) and the electrode body 2. The insulating cover 6 of this embodiment is formed in a bag shape by bending an insulating sheet-like member cut into a predetermined shape.

  In the electricity storage device 1 of the present embodiment, the electrode body 2 (specifically, the electrode body 2 and the current collector 5) housed in the bag-like insulating cover 6 is housed in the case 3.

  The electrode body 2 and the electricity storage device 1 including the electrode body 2 according to the present embodiment are as described above. Then, the manufacturing method of the electrical storage element 1 which concerns on this embodiment is demonstrated, referring FIGS. 8-11.

  First, the core 21 is formed by winding the belt-like sheet 210 into a flat cylindrical shape. Next, as shown in FIG. 8, the start end (end on the winding start side in the longitudinal direction) of the pair (two sheets) of separators 25 is overlapped with the outer peripheral surface of the core 21 by tape, adhesion, welding, or the like. Fixed. The pair of separators 25 are wound around the outer peripheral surface of the core 21 in the same direction as the winding direction of the sheet 210 that constitutes the core 21 in a stacked state. When the pair of separators 25 are wound for a predetermined length, the separator 25 on the inner side (the inner peripheral surface side of the core 21) of the pair of separators 25 and the separator 25 that has already been wound around the core 21. The starting end 240 of the negative electrode 24 is disposed between the first and second separators 25, and the starting end 230 of the positive electrode 23 is disposed between the pair of separators 25 that are wound. In this state, that is, in a state where the positive electrode 23 and the negative electrode 24 are insulated from each other by the separator 25, the positive electrode 23 and the negative electrode 24 are wound around the core 21 together with the pair of separators 25. Hereinafter, the positional relationship between the starting end 230 of the positive electrode 23, the starting end 240 of the negative electrode 24, the first end 210a and the second end 210b of the sheet 210 will be described in more detail with reference to FIGS. As described above, since the thickness of the separator 25 is sufficiently smaller (thin) than the thickness of each of the positive electrode 23, the negative electrode 24, and the sheet 210, in FIGS. 9 to 11, the positive electrode 23, the negative electrode 24, and Only the winding core 21 is shown.

  As shown in FIGS. 9 and 10, the starting end 240 of the negative electrode 24 is disposed at a position adjacent to the second end 210 b on the outer peripheral surface of the winding core 21 (specifically, the position via the separator 25). The start end 230 of the positive electrode 23 is arranged on the core 21 so as to be aligned with the first end 210a in the Z-axis direction (flat direction) at a position shifted from the first end 210a in the Y-axis direction (thickness direction). The

  At this time, the start end 240 of the negative electrode 24 is disposed at a position overlapping with the one linear portion 212 in the Y-axis direction, and the start end 230 of the positive electrode 23 is also disposed at a position overlapping with the one linear portion 212 in the Y-axis direction. .

  Subsequently, as illustrated in FIG. 11, the negative electrode 24 is wound so as to extend from the start end 240 in the direction opposite to the direction in which the sheet 210 extends from the second end 210 b in the Z-axis direction. Further, the positive electrode 23 is wound so as to extend from the start end 230 in a direction opposite to the direction in which the sheet 210 extends from the first end 210a in the Z-axis direction. In the present embodiment, the positive electrode 23, the negative electrode 24, and the separator 25 are wound around the outer peripheral surface of the core 21 by rotating the core 21 around the winding center.

  Thus, the electrode body 2 is obtained by winding the positive electrode 23, the negative electrode 24, and the separator 25 around the outer peripheral surface of the core 21.

  Then, the electrode body 2 obtained by the above-described process is disposed in the case main body 31 from the opening of the case main body 31, and then the opening of the case main body 31 is closed by the cover plate 32. Thereby, the electrode body 2 is accommodated in the case 3, and the electrical storage element 1 is obtained.

  As described above, in the electrode body 2 according to the present embodiment and the power storage device 1 including the electrode body 2, the portion extending from the second end 210 b of the sheet 210 and one electrode plate of the positive electrode 23 and the negative electrode 24. A portion extending from the start end 240 of the negative electrode 24 in the example of the present embodiment is aligned in the circumferential direction of the core 21. For this reason, in the electrode body 2 of the present embodiment, each position in the Z-axis direction is different from the electrode body in which the portion extending from the start end 240 of the negative electrode 24 and the portion extending from the second end 210b of the sheet 210 overlap in the Y-axis direction. Variation in the number of layers in the Y-axis direction (total number of layers of the sheet 210, the positive electrode 23, and the negative electrode 24 in the Y-axis direction) is suppressed. Thereby, the winding surface (the positive electrode 23 and the positive electrode 23 and the positive electrode 23 and the positive electrode 23 and the positive electrode 23 and the positive electrode 23 and the negative electrode 24) is produced by a difference in the number of layers between adjacent portions (regions) in the Z-axis flat direction. The number of step portions on the positive electrode 23 and the outer peripheral surface of the laminate 22 formed by the negative electrode 24 while the negative electrode 24 is wound can be reduced. As a result, it is possible to suppress the generation of wrinkles due to the stepped portion when charging / discharging is repeated.

  Further, in the electrode body 2 of the present embodiment, the positive electrode 23 is arranged so that the start end 230 is aligned with the first end 210a in the Z-axis direction at a position shifted from the arrangement position of the first end 210a in the Y-axis direction. In the state, it extends from the start end 230 in the direction opposite to the direction in which the sheet 210 extends from the first end 210a in the Z-axis direction. For this reason, in the electrode body 2, the stack in the Y-axis direction at each position in the Z-axis direction caused by overlapping the portion extending from the start end 230 of the positive electrode 23 and the portion extending from the first end 210 a of the sheet 210 in the Y-axis direction. The variation in the number is further suppressed. Thereby, in the electrode body 2, the number of level | step-difference parts in the winding surface produced by the difference in the number of lamination | stacking between the site | parts (area | regions) adjacent to a Z-axis flat direction is suppressed more. As a result, in the electrode body 2, generation of wrinkles due to the step portion when charging / discharging is repeated is more reliably suppressed.

  In the electrode body 2 of the present embodiment, the first end 210 a and the second end 210 b of the sheet 210 are disposed at positions corresponding to the linear portion 212 of the winding core 21. As a result, the part extending from the start end 230 of the positive electrode 23 and the part extending from the start end 240 of the negative electrode 24 are directly or indirectly arranged on the linear portion 212 on the outer peripheral surface of the core 21. For this reason, the positive electrode 23 and the negative electrode 24 are wound around the core 21 in a state where the portions extending from the respective start ends 230 and 240 of the positive electrode 23 and the negative electrode 24 are straight, whereby the start end 230 and the negative electrode 24 of the positive electrode 23 are wound. At the starting end 240, a force that tends to move away from the core 21 (a force that the electrode plate arranged in a bent state tries to return straight) hardly occurs. As a result, the start end 230 of the positive electrode 23 and the start end 240 of the negative electrode 24 are prevented from separating from the outer surface of the core 21.

  In the electrode body 2 of the present embodiment, the difference in thickness between the sheet 210 and the positive electrode 23, the difference in thickness between the positive electrode 23 and the negative electrode 24, and the difference in thickness between the sheet 210 and the negative electrode 24 are 60 μm or less. In this way, by suppressing the difference in thickness, it is possible to prevent the stepped portion due to the difference from occurring on the winding surface in the electrode body 2.

  In addition, the electrical storage element of this invention is not limited to the said embodiment, Of course, a various change can be added in the range which does not deviate from the summary of this invention. For example, the configuration of another embodiment can be added to the configuration of a certain embodiment, and a part of the configuration of a certain embodiment can be replaced with the configuration of another embodiment. Furthermore, a part of the configuration of an embodiment can be deleted.

  In the said embodiment, although the case where it was used as a nonaqueous electrolyte secondary battery (for example, lithium ion secondary battery) in which an electrical storage element can be charged / discharged was demonstrated, the kind and magnitude | size (capacity | capacitance) of an electrical storage element are arbitrary. . Moreover, in the said embodiment, although the lithium ion secondary battery was demonstrated as an example of an electrical storage element, it is not limited to this. For example, the present invention can be applied to various secondary batteries, and other power storage elements such as electric double layer capacitors.

  In the electrode body 2 of the above-described embodiment, the start end 240 of the negative electrode 24 is disposed at a position adjacent to the second end 210b of the sheet 210 in the circumferential direction of the core 21 via the separator 25, but is limited to this configuration. Not. For example, as shown in FIG. 12, the start end 240 of the negative electrode 24 may be arranged so as to be aligned with the second end 210b in the Z-axis direction at a position shifted in the Y-axis direction from the arrangement position of the second end 210b. . Also in this case, the negative electrode 24 is wound around the core 21 so as to extend from the start end 240 in the direction opposite to the direction in which the sheet 210 extends from the second end 210b in the Z-axis direction. 12 is a diagram for explaining the positions of the end portions 210a, 210b, 230, and 240. Since the separator 25 is sufficiently thinner than each of the positive electrode 23, the negative electrode 24, and the separator 25, the positive electrode 23, Only the negative electrode 24 and the sheet 210 are shown.

  In the electrode body 2 of the above-described embodiment, the start end 240 of the negative electrode 24 is disposed at a position adjacent to the second end 210b of the sheet 210 in the circumferential direction of the core 21, but is not limited to this configuration. For example, in the electrode body 2, the starting end 230 of the positive electrode 23 may be disposed at a position adjacent to the second end 210 b of the sheet 210 in the circumferential direction of the core 21. In this case, the starting end 240 of the negative electrode 24 is arranged so as to be aligned with the first end 210a in the Z-axis direction at a position shifted in the Y-axis direction from the arrangement position of the first end 210a. In this case, the negative electrode 24 is wound around the core 21 so as to extend from the start end 240 in the direction opposite to the direction in which the sheet 210 extends from the second end 210b in the Z-axis direction.

  The specific method of fixing the first end 210a of the sheet 210 to the inner peripheral surface of the core 21 or fixing the second end 210b of the sheet 210 to the outer peripheral surface of the core 21 is not limited. For example, the first end 210a and the second end 210b may be fixed by tape, adhesion, welding, or the like. Further, the specific method for fixing the starting end 230 of the positive electrode 23 and the starting end 240 of the negative electrode 24 to the outer peripheral surface of the core 21 is not limited. The thickness of the tape is preferably 60 μm or less.

  In the core 21 in the electrode body 2 of the above-described embodiment, the portion extending from the first end 210a of the sheet 210 and the portion extending from the second end 210b extend in the same direction in the Z-axis direction. It is not limited. For example, as shown in FIG. 13, in the core 21, a portion extending from the first end 210 a of the sheet 210 and a portion extending from the second end 210 b may extend in opposite directions in the Z-axis direction. In FIG. 13, for the sake of convenience, the second end 210 b of the sheet 210 and the starting end 240 of the negative electrode 24 are illustrated with a space therebetween. FIG. 13 is a diagram for explaining the positions of the end portions 210a, 210b, 230, and 240. Since the separator 25 is sufficiently thinner than each of the positive electrode 23, the negative electrode 24, and the separator 25, the positive electrode 23, Only the negative electrode 24 and the sheet 210 are shown.

  A power storage element (for example, a battery) may be used in a power storage device 11 (a battery module when the power storage element is a battery) 11 as shown in FIG. The power storage device 11 includes at least two power storage elements 1 and a bus bar member 12 that electrically connects two (different) power storage elements 1 to each other. In this case, the technique of the present invention only needs to be applied to at least one power storage element 1.

  DESCRIPTION OF SYMBOLS 1 ... Power storage element, 2 ... Electrode body, 21 ... Core, 210 ... Sheet, 210a ... First end, 210b ... Second end, 211 ... Curved part, 212 ... Linear part, 22 ... Laminated body, 23 ... Positive electrode, 230 ... Start end, 231 ... Uncoated part, 232 ... Covered part, 24 ... Negative electrode, 240 ... Start end, 241 ... Uncoated part, 242 ... Covered part, 25 ... Separator, 26 ... Uncoated laminated part, Positive electrode uncoated laminated part , Negative electrode non-coated laminated portion, 3 .. case, 31... Case body, 32 .. lid plate, 33 .. internal space, 34 .. opening peripheral portion, 4 .. external terminal, 5. ), 11 ... Power storage device, 12 ... Bus bar member

Claims (5)

A winding core configured by winding a belt-like sheet into a flat cylindrical shape, wherein the first end in the longitudinal direction of the sheet is located on the inner peripheral surface and the first end in the longitudinal direction of the sheet A core whose second end opposite to the outer peripheral surface is located on the outer peripheral surface;
A belt-like positive electrode and a negative electrode wound in the same direction on the outer peripheral surface of the core in a state of being insulated from each other;
The first end and the second end are arranged at positions shifted from each other in the circumferential direction of the core,
Each of the positive electrode and the negative electrode has a starting end disposed directly or indirectly on the outer peripheral surface of the core,
Either the positive electrode or the negative electrode is disposed from the start end in a direction opposite to the extending direction of the sheet from the second end in a state where the start end is disposed adjacent to the second end in the circumferential direction. Extending or arranged so that the starting end is aligned with the second end in the flat direction of the core perpendicular to the thickness direction at a position shifted from the arrangement position of the second end in the thickness direction of the flat core An electrode body extending from the starting end in a state opposite to a direction in which the sheet extends from the second end.   The other electrode plate of the positive electrode or the negative electrode is arranged so that the starting end is aligned with the first end in the flat direction at a position shifted from the arrangement position of the first end in the thickness direction, The electrode body according to claim 1, wherein the electrode body extends from the start end in a direction opposite to a direction in which the sheet extends from the first end. The core is
A pair of curved portions facing each other with a gap in the flat direction;
A pair of straight portions facing each other at an interval in the thickness direction, and having a pair of straight portions connecting corresponding ends of the curved portion,
3. The electrode body according to claim 1, wherein the first end and the second end are arranged at positions corresponding to the linear portion.   The difference in thickness between the sheet and the positive electrode, the difference in thickness between the positive electrode and the negative electrode, and the difference in thickness between the sheet and the negative electrode are 60 μm or less, respectively. The electrode body according to one item. The electrode body according to any one of claims 1 to 4, and
A case for housing the electrode body;
An electrical storage element comprising: an external terminal that is disposed outside the case and is electrically connected to the electrode body.

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