JP6338149B2 - Electricity storage element - Google Patents

Description

  The present invention relates to a power storage element that can be charged and discharged.

  2. Description of the Related Art Conventionally, a power storage element such as a secondary battery including an electrode body around which a laminate in which a positive electrode and a negative electrode are laminated is wound is known (Patent Document 1). In this type of electricity storage element, when the charge / discharge cycle is repeated, the electrode body (the wound electrode plate) is repeatedly expanded and contracted, whereby the positive electrode and the negative electrode constituting the electrode body A wrinkle (particularly a wrinkle extending in a direction crossing the winding direction) may occur.

  When such wrinkles occur in the electrode plate, the gap between the positive electrode and the negative electrode stacked in the electrode body becomes non-uniform, so that the current flowing in the electrode body becomes non-uniform. When the current becomes non-uniform, unevenness in the charging depth occurs in the in-plane direction of the electrode plate, which may cause problems such as a decrease in capacity, an increase in resistance, and the occurrence of lithium electrodeposition.

JP 2012-79650 A

  In view of the above problems, an object of the present invention is to provide a power storage element in which wrinkles are unlikely to occur in a positive electrode and a negative electrode constituting an electrode body even when charging and discharging are repeated.

The electricity storage device according to the present invention is:
An electrode body in which a laminate in which a positive electrode and a negative electrode are laminated is wound, and a hollow portion is formed at the winding center, and has a short diameter and a long diameter, and a pair of curved portions facing each other in the long diameter direction. A flat electrode body;
A tension applying body that applies tension to at least one of the pair of bending portions in a direction in which the pair of bending portions are separated from each other from the hollow portion side, the tension applying body applying force generated by elastic deformation as tension; It is characterized by providing.

  According to such a configuration, the tension applying body applies tension in a direction away from the hollow portion (region surrounded by the wound laminated body) to at least one of the pair of curved portions. Each part of the laminated body is pulled in the winding direction. Thereby, generation | occurrence | production of wrinkles (especially wrinkles extended in the direction which cross | intersects a winding direction) can be prevented effectively in the positive electrode and negative electrode which comprise a laminated body.

  In addition, by adopting a configuration in which the force generated by the elastic deformation is applied to the curved portion as tension, the interval between the curved portions (in the major axis direction) is caused by the expansion and contraction of the laminate (wound positive electrode and negative electrode) accompanying charging and discharging. Even if the (interval) fluctuates, it is possible to continue to suitably apply tension (force to push the curved portions away from each other) to the curved portions while absorbing the fluctuations in the intervals.

The tensioning body is
A first imparting body for applying tension to one of the pair of curved portions;
It is preferable to have a second imparting body that applies tension to the other curved portion of the pair of curved portions.

  According to such a configuration, by applying tension to the pair of curved portions, the expansion and contraction of the electrode body is absorbed by the variation in the distance between the curved portions, and thereby the electrode body (the wound laminate) The dimension in the minor axis direction can be kept constant.

  In addition, since the tension is applied to each of the curved portions, the change in the distance (distance) between the curved portions due to the contraction and expansion of the electrode body due to charge / discharge is simply the winding center (hereinafter referred to as “winding”). It is assigned to both sides in the major axis direction.

The power storage element is
A case for accommodating the electrode body;
The tension applying body is:
A contact member disposed in the hollow portion so as to contact the electrode body from the hollow portion side and extending in the winding center direction of the laminate along the curved portion;
An elastic member that connects the contact member and the case or a member having rigidity in the case, and may apply an elastic member that applies tension to the bending portion by pulling the contact member.

  According to such a configuration, the contact member applies a substantially uniform tension to the curved portion in a wide range in the winding center direction.Therefore, a wide range in the winding center direction of the wound positive electrode and negative electrode is Pulling is reliably performed in the winding direction, and thereby generation of wrinkles extending in a direction intersecting with the winding direction is more effectively prevented.

The storage element is
An external terminal, and a current collector for electrically connecting the electrode body and the external terminal,
The member having rigidity may be a current collector.

  By using a member (current collector) disposed in the case for another purpose as a member for connecting a part of the elastic member to generate an elastic force (a force generated by elastic deformation of the elastic portion) The number of components arranged in the case can be reduced as compared with the case where a member for connecting the elastic member is separately provided in the case. As a result, it is possible to effectively prevent wrinkles while preventing the storage element from becoming large.

The electrode body includes a core around which the laminate is wound,
The tension applying body may apply tension to the curved portion from the inside of the core.

  According to such a configuration, generation of wrinkles can be effectively prevented even in the core.

  As mentioned above, according to this invention, even if charging / discharging is repeated, the electrical storage element with which a wrinkle does not arise easily in the positive electrode and negative electrode which comprise an electrode body can be provided.

FIG. 1 is a perspective view of a power storage device according to an embodiment of the present invention. FIG. 2 is a front view of the energy storage device according to the embodiment. 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 energy storage device according to the embodiment. FIG. 6 is a view for explaining the configuration of the electrode body of the energy storage device according to the embodiment. FIG. 7 is a front view of the current collector of the energy storage device according to the embodiment. FIG. 8 is a side view of the current collector of the energy storage device according to the embodiment. FIG. 9 is a perspective view of a current collector of the energy storage device according to the embodiment. FIG. 10 is a conceptual diagram for explaining a state in which the contact member of the tension applying body and the current collector are connected in the energy storage device according to the embodiment. 11 is a cross-sectional view taken along the line III-III of FIG. 1 in the energy storage device according to one embodiment. 12 is a cross-sectional view taken along the line III-III of FIG. 1 in the energy storage device according to one embodiment. FIG. 13 is a perspective view of a power storage device including a power storage element according to an embodiment.

  Hereinafter, an embodiment of a power storage device according to the present invention will be described with reference to FIGS. Examples of the power storage element include a primary battery, a secondary battery, and a capacitor. 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 component (each component) of this embodiment is a thing in this embodiment, and may differ from the name of each component (each component) 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 6, the storage element 1 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 6, the electrode body 2 is a laminated body 22 in which a winding core 21, a positive electrode 23, and a negative electrode 24 are laminated in a mutually insulated state, and is wound around the winding core 21. The laminated body 22 is provided. The electrode body 2 is formed flat. Therefore, the electrode body 2 has a short diameter and a long diameter. As shown in FIG. 4, the electrode body 2 has a pair of curved portions 211 that face each other in the major axis direction. As the lithium ions move between the positive electrode 23 and the negative electrode 24 in the electrode body 2, the power storage device 1 is charged and discharged.

  The winding core 21 is usually formed of an insulating material. The winding core 21 has a cylindrical shape. The core 21 of this embodiment is a flat cylindrical shape. Specifically, the winding core 21 includes a pair of curved portions 213 facing each other with a space therebetween, and a pair of linear portions 212 facing each other, corresponding to the curved portions 213 (facing the arrangement direction of the pair of curved portions 213). And a pair of linear portions 212 that connect the end portions to each other (see FIG. 4). Each bending portion 213 is curved so as to protrude outward (in a direction away from each other). The pair of straight portions 212 are parallel or substantially parallel. The winding core 21 of this embodiment is formed by winding a sheet having flexibility or thermoplasticity. The winding core 21 is formed of a flexible material so as to be deformed when a force is applied.

  The sheet is formed of a synthetic resin. The sheet is resistant to the electrolytic solution. The sheet is made of, for example, polypropylene (PP), polyethylene (PE), polyphenylene sulfide (PPS), or polyethylene terephthalate (PET). The thickness of the sheet is, for example, 50 μm to 200 μm. The sheet of the present embodiment is made of, for example, polypropylene, and the thickness of the sheet is, for example, 150 μm. The material of the sheet constituting the winding core 21 is not limited to the synthetic resin, and may be a metal such as aluminum or copper.

  As shown in FIG. 6, 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). By winding the laminated body 22, a hollow portion 27 is formed at the winding center of the electrode body 2.

  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 (a portion where the positive electrode active material layer is not formed) 231 of the positive electrode active material layer at one edge portion in the width direction that is the short direction of the band shape. 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 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 (negative electrode active material layer) of the negative electrode active material layer formed on the other edge portion in the width direction that is the short direction of the belt shape (on the side opposite to the non-covered portion 231 of the positive electrode 23). 241). The width of the covering portion (the portion where the negative electrode active material layer is formed) 242 of the negative electrode 24 is larger than the width of the covering portion 232 of the positive electrode 23.

  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. The separator 25 is an insulating member. 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 uncoated laminated portion 26 is a portion that is electrically connected to the current collector 5 in the electrode body 2. The uncoated laminated portion 26 of the present embodiment is divided into two parts (divided into two parts) with the hollow portion 27 (see FIG. 6) in between when the wound positive electrode 23, negative electrode 24, and separator 25 are viewed in the winding center direction. Uncovered laminated portion) 261.

  The uncoated laminated portion 26 configured as described above is provided on 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.

  As shown in FIGS. 3 and 4, in the electricity storage device 1, the pair of curved portions 211 are separated from each other from the hollow portion 27 side with respect to at least one of the pair of curved portions 211 in the electrode body 2 (in FIG. 4). A tension applying body 28 that applies force in the direction indicated by the arrow) is provided. In the present embodiment, the tension applying body 28 includes a first applying body 280 </ b> A that applies a force to one bending portion 211 of the pair of bending portions 211 in the electrode body 2, and the other of the pair of bending portions 211. And a second applicator 280B that applies a force to the curved portion 211. Here, the one bending portion 211 is the bending portion 211 located on the cover plate 32 side. The other bending portion 211 is the bending portion 211 located on the closing portion 311 side.

  The first imparting body 280A includes a contact member 282 disposed on the cover plate 32 side in the hollow portion 27 so as to contact the electrode body 2 in the hollow portion 27, and the contact member 282 and the case 3 or the case 3 And an elastic member 281 for connecting the member having the rigidity of the above.

  The contact member 282 of the first imparting body 280A is formed in a rod shape by a rigid insulating material. The contact member 282 of this embodiment has a cylindrical shape. The contact member 282 extends in the winding center direction of the stacked body 22 along the curved portion 211. The contact member 282 is inserted into the hollow portion 27 along the curved portion 211. The length of the contact member 282 in the longitudinal direction is substantially the same as the length of the core 21 in the longitudinal direction. The abutting member 282 is arranged with the length of the core 21 in the longitudinal direction. The contact member 282 is disposed so as to contact the curved portion 213 of the core 21.

  The elastic member 281 of the first imparting body 280A is formed of an insulating material having elasticity. The elastic member 281 of the present embodiment is an annular elastic body (here, an annular member made of rubber). The elastic member 281 is inserted through the contact member 282. As shown in FIG. 5, the elastic member 281 is formed to have a length that partially protrudes from both ends of the electrode body 2. The elastic member 281 connects the contact member 282 and a member having rigidity in the case 3. In the present embodiment, the member having rigidity in the case 3 is the current collector 5. The elastic member 281 is hooked on a first notch 571 described later of the current collector 5.

  The elastic member 281 of the first applicator 280A connects the contact member 282 of the first applier 280A and the current collector 5 in an extended state. That is, a restoring force acts on the elastic member 281. Therefore, both end portions of the contact member 282 of the first applicator 280A are pulled in the major axis direction of the electrode assembly 2 by the elastic member 281 of the first applier 280A.

  The second imparting body 280B includes a contact member 282 disposed on the closed portion 311 side in the hollow portion 27 so as to contact the electrode body 2 in the hollow portion 27, and the contact member 282 and the case 3 or the case 3 And an elastic member 281 for connecting the member having the rigidity of the above.

  The contact member 282 of the second imparting body 280B is formed in a rod shape by a rigid insulating material. The contact member 282 of this embodiment has a cylindrical shape. The contact member 282 extends in the winding center direction of the stacked body 22 along the curved portion 211. The contact member 282 is inserted into the hollow portion 27 along the curved portion 211. The length of the contact member 282 in the longitudinal direction is substantially the same as the length of the winding core 21 in the winding center direction. The abutting member 282 is arranged with the length of the core 21 in the longitudinal direction. The contact member 282 is disposed so as to contact the curved portion 213 of the core 21.

  The elastic member 281 of the second imparting body 280B is formed of an insulating material having elasticity. The elastic member 281 of the present embodiment is an annular elastic body (here, an annular member made of rubber). The elastic member 281 is inserted through the contact member 282. As shown in FIG. 5, the elastic member 281 is formed to have a length that partially protrudes from both ends of the electrode body 2. The elastic member 281 connects the contact member 282 and a member having rigidity in the case 3. In the present embodiment, the member having rigidity in the case 3 is the current collector 5. The elastic member 281 is hooked on a second notch 572 (described later) of the current collector 5.

  The elastic member 281 of the second applicator 280B connects the contact member 282 of the second applier 280B and the current collector 5 in an extended state. That is, a restoring force acts on the elastic member 281. Accordingly, both end portions of the contact member 282 of the second applicator 280B are pulled in the major axis direction of the electrode assembly 2 by the elastic member 281 of the second applier 280B.

  The elastic members 281 of the first applicator 280A and the second applier 280B preferably pull the contact member 282 in the major axis direction of the electrode body 2 with an equal force. That is, as shown in FIG. 3, it is preferable that L1 and L2 after the tension is applied to the electrode body 2 are equal to the center line L before the electrode body 2 is tensioned.

  As described above, the first imparting body 280 </ b> A and the second imparting body 280 </ b> B apply force in a direction in which the pair of curved portions 211 are separated by pulling the pair of curved portions 211. Thereby, tension is applied in the winding direction at each part of the electrodes constituting 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 lid plate 32 is a plate-like member that closes the opening of the case body 31. Specifically, the cover plate 32 contacts the case body so as to close the opening of the case body 31. More specifically, the peripheral edge of the cover plate 32 is overlapped with the open peripheral edge 34 of the case body 31 so that the cover plate 32 closes the opening. In a state where the opening peripheral edge 34 and the cover plate 32 are overlapped, the boundary portion between the cover plate 32 and the case main body 31 is welded. Thereby, the case 3 is configured.

  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. For example, the external terminal 4 is formed of a highly weldable metal material such as an aluminum-based metal material such as aluminum or an aluminum alloy, or a copper-based metal material such as copper or a copper alloy.

  The current collector 5 is disposed in the case 3 and is directly or indirectly connected to the electrode body 2 so as to be energized. The current collector 5 of the present embodiment is connected to the electrode body 2 through the clip member 50 so as to be energized. That is, the electrical storage element 1 includes a clip member 50 that connects the electrode body 2 and the current collector 5 so as to allow energization.

  The current collector 5 is formed of a conductive member. As shown in FIG. 3, the current collector 5 is disposed along the inner surface of the case 3. The current collector 5 of the present embodiment connects the penetrating member 7 and the clip member 50 so as to be energized. Specifically, the current collector 5 includes a first connection portion 51 that is connected to the penetrating member 7 so as to be energized, a second connection portion 52 that is connected to the electrode body 2 so as to be energized, and a first connection portion 51. And a bent portion 53 that connects the second connecting portion 52. In the current collector 5, the bent portion 53 is disposed in the vicinity of the boundary between the lid plate 32 and the short wall portion 314 in the case 3, the first connection portion 51 extends from the bent portion 53 along the lid plate 32, and Two connecting portions 52 extend from the bent portion 53 along the short wall portion 314. That is, the current collector 5 is formed in an L shape. The current collector 5 of the present embodiment is formed by bending a plate-shaped metal material cut into a predetermined shape.

  The first connection portion 51 is a portion that is connected to the penetrating member 7 so as to be energized. Specifically, the first connection portion 51 extends from the bent portion 53 along the inner surface of the case 3 (lid plate 32) while being insulated from the case 3 (specifically, the lid plate 32). The 1st connection part 51 is a plate-shaped site | part. A hole 54 through which the penetrating member 7 is inserted is formed at the distal end portion of the first connection portion 51. The hole 54 is provided at a position overlapping the through hole 322 of the lid plate 32 in the Z-axis direction.

  The second connection part 52 is connected to the electrode body 2 (in this embodiment, the non-covered laminated part 26 of the electrode body 2) via the clip member 50 so as to be conductive. Specifically, the second connection portion 52 extends from the bent portion 53 along the inner surface of the case 3 (short wall portion 314) while being insulated from the case 3 (specifically, the short wall portion 314). The second connection portion 52 has at least one joining piece 55 that extends from the vicinity of the short wall portion 314 toward the uncoated laminated portion 26 and extends in the same direction as the second connection portion 52. The joining piece 55 is joined to the clip member 50. The joining piece 55 of this embodiment is joined with the clip member 50 by ultrasonic welding, for example.

  The second connection part 52 has two joining pieces 55 and 55. Specifically, the second connecting portion 52 has two joining pieces 55 extending in the Z-axis direction on both sides of the opening 56 so as to define an opening 56 provided in the center in the Y-axis direction. That is, the second connection part 52 includes a joining piece 55 to be joined to the clip member 50 sandwiching one of the two uncoated laminated parts 261 in each uncoated laminated part 26 and the two uncoated laminated parts. And a joining piece 55 joined to the clip member 50 sandwiching the other of the portions 261. The opening 56 and the two joining pieces 55 are formed by, for example, making a notch in the Z-axis direction (longitudinal direction) in the band plate before forming the second connection portion 52 and twisting both sides of the notch.

  The second connection portion 52 is configured to be able to connect the contact member 282 and the current collector 5 via the elastic member 281. Specifically, the second connection portion 52 is formed with a notch portion 57 (see FIG. 5) that hooks the elastic member 281. As shown in FIGS. 7 to 9, the notch portion 57 is formed at both ends in the Z-axis direction of the second connection portion 52 with the opening 56 interposed therebetween. The cutout portion 57 is formed so that two recesses face each other in the Y-axis direction.

  As shown in FIG. 10, the notch portion 57 includes a first notch portion 571 on which the elastic member 281 of the first imparting body 280A is hooked and a second notch portion 572 on which the elastic member 281 of the second imparting body 280B is hooked. Have. When each elastic member 281 is hooked by the notches 571 and 572, the contact member 282 and the current collector 5 are connected without being displaced.

  The current collector 5 configured as described above is disposed on each of the positive electrode and the negative electrode of the electricity storage device 1. In the electricity storage device 1 of the present embodiment, the current collectors 5 are disposed in the case 3 in the positive electrode uncoated stacked portion 26 and the negative electrode uncoated stacked portion 26 of the electrode body 2, respectively.

  The positive electrode current collector 5 and the negative electrode current collector 5 are formed of different materials. Specifically, the positive electrode current collector 5 is formed of, for example, aluminum or an aluminum alloy, and the negative electrode current collector 5 is formed of, for example, copper or a copper alloy.

  The power storage device 1 according to the present embodiment described above is an electrode body 2 around which a laminated body 22 in which a positive electrode 23 and a negative electrode 24 are laminated, and a hollow portion 27 is formed at the center of winding and a short diameter. In addition, the pair of curved portions 211 are separated from the hollow portion 27 side with respect to at least one of the flat electrode body 2 having a long diameter and having a pair of curved portions 211 opposed in the long diameter direction, and the pair of curved portions 211. A tension imparting body 28 that imparts tension in a direction, and a tension imparting body 28 that imparts a force generated by elastic deformation as tension.

  According to this configuration, the tension applying body 28 applies tension to at least one of the pair of curved portions 211 in a direction away from each other from the hollow portion 27 (region surrounded by the wound laminated body 22) side. Therefore, each part of the laminated body 22 being wound is pulled in the winding direction. Thereby, generation | occurrence | production of wrinkles (especially wrinkles extended in the direction which cross | intersects a winding direction) can be effectively prevented in the positive electrode and negative electrode which comprise the laminated body 22. FIG.

  In addition, by adopting a configuration in which the force generated by the elastic deformation is applied to the bending portion 211 as a tension, the bending portion 211 can be expanded and contracted by the expansion and contraction of the stacked body 22 (the wound positive electrode 23 and the negative electrode 24). Even if the interval (interval in the major axis direction) fluctuates, it is possible to continue to apply tension (force that pushes the bending portion 211 away from each other) to the bending portion 211 while absorbing the fluctuation in the interval. .

  The tension applying body 28 applies tension to the first bending section 280A that applies tension to one bending section 211 of the pair of bending sections 211 and the other bending section 211 of the pair of bending sections 211. It is preferable to have the second imparting body 280B to be added.

  According to such a configuration, by applying tension to the pair of curved portions 211, the expansion and contraction of the electrode body 2 are absorbed by the variation in the spacing between the curved portions 211, and thereby the electrode body 2 (wound) The dimension in the minor axis direction of the laminate 22) can be kept constant. As a result, in the internal space of the case 3 (the space in which the electrode body 2 is accommodated), it is not necessary to secure a variation allowance of the dimension of the electrode body 2 in the minor axis direction due to charge / discharge. The dimension in the direction can be suppressed.

Since tension is applied to each of the curved portions 211, the change in the distance (distance) between the curved portions 211 due to the contraction and expansion of the electrode body 2 due to charging / discharging is the winding center of the electrode plate (hereinafter simply “ (Referred to as “winding center”). For this reason, the movement of the winding center in the major axis direction in the case 3, that is, the movement in the major axis direction of the portion near the winding center of the electrode body 2 in the case 3 can be suppressed.

  The power storage element 1 includes a case 3 that houses the electrode body 2, and the tension applying body 28 is a contact member 282 that is disposed in the hollow portion 27 so as to contact the electrode body 2 in the hollow portion 27. An abutting member 282 extending in the winding center direction of the laminate 22 along the curved portion 211, and an elastic member 281 for connecting the abutting member 282 to the case 3 or a member having rigidity in the case 3, An elastic member 281 that applies tension to the bending portion 211 by pulling the contact member 282.

  According to such a configuration, the contact member 282 applies a substantially uniform tension to the bending portion 211 in a wide range in the winding center direction. Therefore, the winding of the positive electrode 23 and the negative electrode 24 in the winding center direction is performed. A wide range is surely pulled in the winding direction, and thus the generation of wrinkles (the wrinkles extending in the direction crossing the winding direction) is more effectively prevented.

  The power storage element 1 includes an external terminal 4 and a current collector 5 that electrically connects the electrode body 2 and the external terminal 4, and the rigid member may be the current collector 5.

  As a member for connecting a part of the elastic member 281 to generate an elastic force (a force generated by elastic deformation of the elastic portion), a member (current collector 5) disposed in the case 3 for other purposes is used. By doing so, the number of components arranged in the case 3 can be reduced as compared with the case where a member for connecting the elastic member 281 is separately provided in the case 3. Thereby, wrinkles can be prevented without increasing the size of the power storage element 1.

  The electrode body 2 includes a winding core 21 and a winding core 21 around which the laminated body 22 is wound. The tension applying body 28 may apply tension to the bending portion 211 from the inside of the winding core 21. Good. Although the winding core 21 concerning this embodiment is a flat cylindrical shape, it is not restricted to this. That is, it is sufficient if tension can be applied to the bending portion 211 from the inside. For example, a winding core having a plate shape or a sheet shape and having a hole through which an elastic member is inserted may be used. Specifically, it may be a plate or sheet-like member, and may be a core provided with a hole (or a cylindrical portion) at the opposite end of the member.

  According to this configuration, generation of wrinkles (particularly wrinkles extending in a direction intersecting with the winding direction of the laminate 22) can be effectively prevented even in the core 21.

  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 above embodiment, tension is applied to the electrode body 2 by applying force to both the pair of curved portions 211 with an elastic member, but the present invention is not limited to this. You may give tension | tensile_strength with respect to the electrode body 2 by applying force to one curved part 211 of a pair of curved parts 211 with an elastic member. That is, tension may be applied to the electrode body 2 by pulling one of the curved portions 211. In this case, as illustrated in FIG. 11, the tension applying body 28 includes a first applying body 280A that pulls one bending portion 211 of the pair of bending portions 211 in a direction in which the pair of bending portions 211 are separated from each other, It is preferable that the fixing member 8 is configured to fix the electrode body 2 on the other curved portion 211 side. Here, as shown in FIG. 11, one bending portion 211 is the bending portion 211 located on the cover plate 32 side. The other bending portion 211 is the bending portion 211 located on the closing portion 311 side.

  In this case, the first imparting body 280A includes a contact member 282 disposed in the hollow portion 27 so as to contact the electrode body 2 in the hollow portion 27, and a rigidity in the contact member 282 and the case 3 or the case 3. And an elastic member 281 connecting the member having In the present embodiment, the member having rigidity in the case 3 is the current collector 5.

  The fixing member 8 is configured to be able to fix the electrode body 2. Specifically, the fixing member 8 fixes the electrode body 2 on the closing portion 311 side of the pair of bending portions 211. The fixing member 8 is formed in a rod shape by a rigid insulating material. As shown in FIG. 11, the fixing member 8 is disposed in the hollow portion 27 so as to contact the electrode body 2 in the hollow portion 27. The fixing member 8 extends in the winding center direction of the stacked body 22 along the curved portion 211. Both end portions of the fixing member 8 penetrate the current collector 5. Both ends of the fixing member 8 and the current collector 5 are joined by a known joining technique, and the fixing member 8 is fixed to the current collector 5. The electrode body 2 is fixed on the closing portion 311 side by sandwiching the bending portion 211 on the closing portion 311 side in the electrode body 2 between the closing portion 311 and the fixing member 8.

  Contrary to the above case, tension may be applied to the electrode body 2 by pulling the curved portion 211 of the other (blocking portion 311) by the second applying body 280B. In this case, the electrode body 2 is a fixing member. 8 is fixed on the cover plate 32 side.

  In the above embodiment, the tension applying body 28 applies tension to the electrode body 2 by connecting the contact member 282 and the current collector 5 (using the case 3 or the like). It is not limited. The tension applying body 28 may apply tension to the electrode body 2 without using the case 3 or the like. That is, the tension applying body 28 may apply tension to the electrode body 2 by pressing both the pair of curved portions 211 from the hollow portion 27 side. The tension applying body 28 is preferably formed of an elastically deformable insulating material. In this case, the tension applying body 28 is preferably made of rubber. As shown in FIG. 12, the tension applying body 28 is disposed in a gap defined by the pair of curved portions 213 and the pair of straight portions 212 in the core 21. The tension applying body 28 has a short diameter and a long diameter.

  In the above case, the tension applying body 28 has a major axis longer than the interval in the Z-axis direction between the pair of curved portions 213 in the core 21. Therefore, the tension applying body 28 is contracted in the Z-axis direction and disposed in the core 21. A restoring force acts on the tension applying body 28 in the core 21. That is, both of the pair of curved portions 211 in the electrode body 2 are pushed from the hollow portion 27 side by the tension applying body 28. As a result, the pair of bending portions 211 in the electrode body 2 are pushed away from each other. As a result, tension is applied in the winding direction at each part of the electrode constituting the electrode body 2.

  In the above case, the tension applying body 28 may apply tension to the electrode body 2 by applying force only to one of the bending portions 211 of the pair of bending portions 211. In this case, both end portions of the fixing member 8 penetrate the current collector 5. Both ends of the fixing member 8 and the current collector 5 are joined by a known joining technique, and the fixing member 8 is fixed to the current collector 5. When one of the pair of curved portions 211 in the electrode body 2 is sandwiched between the lid plate 32 or the closing portion 311 and the fixing member 8, the electrode body 2 is fixed on the lid plate 32 side or the closing portion 311 side. Is done.

  In the above case, the tension applying body 28 may include a pair of contact members 282 that are respectively directed to the inner peripheral surfaces of the pair of bending portions 211. As a result, tension is applied to the curved portion 211 in a wide range in the winding center direction substantially uniformly, so that the wide range in the winding center direction of the positive electrode 23 and the negative electrode 24 being wound is the major axis of the electrode body 2. Generation of wrinkles that are surely pushed in the direction and extend in the direction intersecting the winding direction is more effectively prevented.

  In the above case, the tension applying body 28 may be an elastic body such as a spring as long as it can apply tension in a direction in which the pair of curved portions 211 in the electrode body 2 are separated from each other. The spring or the like may be a metal such as aluminum or copper as long as it is covered with an insulating material.

  In the above embodiment, the electrode body 2 is a laminated body 22 that is laminated in a state where the positive electrode 23 and the negative electrode 24 are insulated from each other, and includes the laminated body 22 that is wound around the core 21. Although described, it is not limited to this. The electrode body 2 may be formed by winding the laminated body 22 laminated in a state where the positive electrode 23 and the negative electrode 24 are insulated from each other. That is, the laminate 22 may not be wound around the core 21.

  In the above embodiment, the elastic member 281 is an annular elastic body (here, an annular member made of rubber), and the case where the elastic member 281 is inserted through the contact member 282 has been described, but is not limited thereto. The elastic member 281 may be any member that can connect the contact member 282 and the case 3 or a member having rigidity in the case 3. For example, the elastic member 281 may have a shape in which a part of the elastic member 281 is fixed in the cylinder of the cylindrical contact member 282 and can be hooked on the notch 57 of the current collector 5.

  In the above embodiment, the case where the member having rigidity in the case 3 connected to the contact member 282 is the current collector 5 is described, but the present invention is not limited to this. The member connected to the contact member 282 may be a member having rigidity such as the case 3 other than the current collector 5. For example, when the member connected to the contact member 282 is the case 3, the elastic member 281 may be hooked on a hook or the like provided on the case 3, avoiding the current collector 5.

  In the above-described embodiment, the case where the elastic member 281 is hooked on the notch 57 of the current collector 5 in order to connect the contact member 282 and the current collector 5 has been described, but the present invention is not limited to this. For example, the elastic member 281 may connect the contact member 282 and the current collector 5 by hooking the elastic member 281 to a hook or an angle-shaped member protruding from the current collector 5.

  Moreover, although the case where the contact member 282 was used was demonstrated in the said embodiment, this invention is not limited to this. That is, tension may be directly applied to the bending portion 211 by the elastic member 281 without using the contact member 282.

  Moreover, in the said embodiment, although the case where an electrical storage element was used as a nonaqueous electrolyte secondary battery (for example, lithium ion secondary battery) which can be charged / discharged was demonstrated, the kind and magnitude | size (capacity | capacitance) of an electrical storage element are arbitrary. It is. 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, other primary batteries, and power storage elements of capacitors such as electric double layer capacitors.

  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, 211 ... Curved part, 212 ... Linear part, 213 ... Curved part, 22 ... Laminated body, 23 ... Positive electrode, 231 ... Uncovered part, 232 ... Covered part, 24 ... Negative electrode, 241 ... Non-covered portion, 242 ... Covered portion, 25 ... Separator, 27 ... Hollow portion, 28 ... Tension applying body, 280A ... First applying body, 280B ... Second applying body, 281 ... Elastic member, 282 Reference member, 3 ... Case, 31 ... Case body, 311 ... Closure, 32 ... Cover plate, 322 ... Through hole, 33 ... Internal space, 4 ... External terminal, 5 ... Current collector, 50 ... Clip member, 56 ... Opening, 57 ... Notch, 571 ... First notch, 572 ... Second notch, 6 ... Insulating member (insulating cover), 7 ... Penetration member, 8 ... Fixing member, 11 ... Power storage device, 12 ... Bus bar member, L ... center line

Claims (3)

An electrode body in which a laminate in which a positive electrode and a negative electrode are laminated is wound, and a hollow portion is formed at a winding center, and a pair of curved portions having a minor axis and a major axis and facing each other in the major axis direction. A flat electrode body having,
A tension applying body that applies tension to at least one of the pair of bending portions in a direction in which the pair of bending portions separate from each other from the hollow portion side, and applies tension generated by elastic deformation as the tension. Body,
A case for housing the electrode body ,
The tension applying body is:
A contact member disposed in the hollow portion so as to contact the electrode body from the hollow portion side and extending in the winding center direction of the laminate along the curved portion;
An elastic member for connecting the member having rigidity in said contact member and the case or casing, wherein the elastic member for applying tension to the bending portion by pulling the abutment member, the Rukoto to have a A power storage element is characterized. An external terminal, and a current collector for conducting the electrode body and the external terminal,
The power storage element according to claim 1 , wherein the rigid member is the current collector. An electrode body in which a laminate in which a positive electrode and a negative electrode are laminated is wound, and a hollow portion is formed at a winding center, and a pair of curved portions having a minor axis and a major axis and facing each other in the major axis direction. A flat electrode body having,
A tension applying body that applies tension to at least one of the pair of bending portions in a direction in which the pair of bending portions separate from each other from the hollow portion side, and applies tension generated by elastic deformation as the tension. With body,
The electrode body includes a core around which the laminate is wound,
The tensioning body, applying tension to the curved portion of the laminate through the winding core from the inside of the core, a charge reservoir element.

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