JP2018120789A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of inhibiting an electrode assembly and a case from being short-circuited without reducing the capacity.SOLUTION: A secondary battery 10 includes: an electrode assembly 12 having a plurality of positive electrodes 20 and a plurality of negative electrodes 40; a bottomed cylindrical case body 13 housing the electrode assembly 12 therein; and an insulation sheet 50 for insulating the electrode assembly 12 and the case body 13. The insulation sheet 50 includes: a bottom surface covering part 50a interposed between an inner bottom surface 13b of the case body 13 and a bottom surface 12b of the electrode assembly 12; and a side surface covering part 50b covering the side surface 12c of the electrode assembly 12. The bottom surface covering part 50a has a thick wall part 53 which is thicker than the thickness of the side surface covering part 50b.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power storage device including an electrode assembly having a plurality of positive electrodes and negative electrodes, a bottomed cylindrical case that houses the electrode assembly, and an insulating sheet that insulates the electrode assembly from the case. .

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug-in Hybrid Vehicle) is equipped with a secondary battery as a power storage device that stores power supplied to a traveling motor. The secondary battery includes an electrode assembly having a sheet-like positive electrode and a negative electrode, and a bottomed cylindrical case that accommodates the electrode assembly. Moreover, the electrode assembly and the case are insulated by covering the electrode assembly with an insulating sheet formed in a bottomed cylindrical shape (see Patent Document 1).

JP2015-32386A

  Incidentally, in the secondary battery, in order to increase the capacity, it is desired to increase the volume of the electrode assembly that occupies the case. For this reason, it is preferable that the insulating sheet interposed between the case and the electrode assembly is thinner.

  On the other hand, the electrode assembly is supported on the inner bottom surface of the case via an insulating sheet, and the insulating sheet is placed between the bottom surface of the electrode assembly and the inner bottom surface of the case by vibration during use of the secondary battery. The electrode assembly and the case may be short-circuited.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power storage device that can suppress a short circuit between the electrode assembly and the case without reducing the capacity.

  A power storage device for solving the above problems includes an electrode assembly having a plurality of positive electrodes and a plurality of negative electrodes, a bottomed cylindrical case for housing the electrode assembly, the electrode assembly, and the case A power storage device including an insulating sheet that insulates the bottom of the case, the insulating sheet including a bottom surface covering portion interposed between an inner bottom surface of the case and a bottom surface of the electrode assembly, and a side surface of the electrode assembly And the bottom face covering part has a thick part thicker than the thickness of the side face covering part.

  According to this, the thick portion is interposed between the bottom surface of the electrode assembly and the inner bottom surface of the case. The thick part is thicker than the side cover part, and even if it contacts the inner bottom surface of the case due to vibration during use of the power storage device, it is difficult to tear. Further, while forming the thick portion on the bottom surface covering portion, the side surface covering portion that covers the side surface of the electrode assembly is thinned, so that the number of positive electrodes and negative electrodes that can be accommodated in the case is not reduced. Therefore, a short circuit between the bottom surface of the electrode assembly and the inner bottom surface of the case can be suppressed without reducing the capacity of the power storage device.

  Further, for the power storage device, the insulating sheet includes a first sheet that constitutes the bottom face cover portion, and a second sheet that constitutes the bottom face cover portion and the side face cover portion, and the first sheet includes the first sheet, Preferably, the thick part is located between the bottom surface of the electrode assembly and the second sheet, and the thick sheet is formed by overlapping the first sheet and the second sheet.

According to this, since the thick part is formed by stacking two insulating sheets, the thick part can be easily formed rather than manufacturing the thick part and the thinner part than the thick part on one insulating film. Can be manufactured.
In the power storage device, the surface of the first sheet on the electrode assembly side is preferably an adhesive surface.

According to this, even if a part of the electrode assembly falls off and foreign matter is generated, the foreign matter adheres to the adhesive surface of the first sheet. Therefore, it is possible to suppress foreign matter from being scattered in the power storage device.
In the power storage device, the size of the first sheet is preferably the same as the size of the bottom surface of the electrode assembly.

  According to this, the size of the thick portion (the portion where the first sheet and the second sheet overlap) can be made the same as the size of the bottom surface of the electrode assembly. Therefore, even if any part of one of the first sheet and the second sheet constituting the bottom surface covering portion is torn, the insulating state between the electrode assembly and the case can be maintained by the other sheet. Can be further suppressed.

  Further, for the power storage device, the insulating sheet includes a first sheet that constitutes the bottom face cover portion, and a second sheet that constitutes the bottom face cover portion and the side face cover portion, and the first sheet includes the first sheet, Preferably, the thick portion is located between the second sheet and the inner bottom surface of the case, and the thick sheet is formed by overlapping the first sheet and the second sheet.

  According to this, since the thick portion is formed by stacking two sheets, it is easier to manufacture the thick portion than to manufacture the thick portion and the portion thinner than the thick portion on one insulating film. it can. Further, if the first sheet is disposed on the bottom surface of the case before the electrode assembly and the second sheet are accommodated in the case, a thick portion can be formed when the electrode assembly and the second sheet are accommodated in the case.

In the power storage device, the size of the first sheet is preferably the same as the size of the inner bottom surface of the case.
According to this, the size of the thick portion (the portion where the first sheet and the second sheet overlap) can be made the same as the size of the inner bottom surface of the case that is larger than the bottom surface of the electrode assembly. Therefore, even if any part of one of the first sheet and the second sheet constituting the bottom cover portion is torn, the insulating state between the electrode assembly and the case can be maintained by the other sheet. Moreover, since the thickness part can be made larger than the case where the magnitude | size of a 1st sheet | seat is made the same as the magnitude | size of the bottom face of an electrode assembly, the short circuit with an electrode assembly and a case can be suppressed more. Moreover, since the magnitude | size of a 1st sheet | seat can be determined according to the inner bottom face of the case which is a rigid body, a 1st sheet | seat can be manufactured easily.

In the power storage device, the material of the first sheet is preferably the same as the material of the second sheet.
According to this, it is not necessary to prepare the material for the first sheet and the material for the second sheet separately.

  According to the present invention, it is possible to suppress the tearing of the insulating sheet without reducing the capacity.

The disassembled perspective view of the secondary battery of 1st Embodiment. The disassembled perspective view of the electrode assembly of 1st Embodiment. The fragmentary sectional view of the secondary battery of a 1st embodiment. The disassembled perspective view of the secondary battery of 2nd Embodiment. The fragmentary sectional view of the secondary battery of 2nd Embodiment. The disassembled perspective view of the secondary battery of 3rd Embodiment. The fragmentary sectional view of the secondary battery of a 3rd embodiment.

(First embodiment)
Hereinafter, a first embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.

  As shown in FIG. 1, a secondary battery 10 as a power storage device includes a rectangular parallelepiped case 11, and an electrode assembly 12 is accommodated in the case 11. The case 11 includes a case main body 13 made of metal having a bottomed rectangular tube shape (for example, made of aluminum or aluminum alloy) and a lid 14 that closes the opening 13 a of the case main body 13. The case body 13 includes an inner bottom surface 13b (shown in FIG. 3) and four side walls 13c connected to the inner bottom surface 13b. An electrolyte (electrolytic solution) (not shown) is accommodated in the case 11. The secondary battery 10 of this embodiment is a lithium ion secondary battery.

  The secondary battery 10 includes a positive electrode terminal 15 and a negative electrode terminal 16 as terminals for taking out electricity from the electrode assembly 12. The positive electrode terminal 15 and the negative electrode terminal 16 penetrate the through hole 14 a of the lid 14 and protrude out of the case 11. A ring-shaped insulating ring 17 for insulating from the case 11 is attached to each of the positive terminal 15 and the negative terminal 16. The positive electrode terminal 15 has a positive electrode conductive member 15 a as a rectangular plate-shaped conductive member in the case 11. The positive electrode terminal 15 is electrically connected to the positive electrode conductive member 15a. The negative electrode terminal 16 has a negative electrode conductive member 16 a as a rectangular plate-shaped conductive member in the case 11. The negative electrode terminal 16 is electrically connected to the negative electrode conductive member 16a.

  As shown in FIG. 2, the electrode assembly 12 includes an electrode storage separator 30 that stores a positive electrode 20 as an electrode, and a negative electrode 40 as an electrode having a polarity different from that of the positive electrode 20. The electrode assembly 12 has a layered structure in which a plurality of electrode storage separators 30 and a plurality of negative electrodes 40 are alternately stacked. Thereby, the some positive electrode 20 and the some negative electrode 40 are laminated | stacked alternately in the state which pinched | interposed the separator member 31 of the electrode storage separator 30 in between. In the present embodiment, the positive electrode 20, the separator member 31, and the negative electrode 40 are all rectangular. The direction in which the electrode storage separator 30 and the negative electrode 40 are stacked is defined as the stacking direction of the electrode assembly 12.

  The positive electrode 20 includes a rectangular sheet-like positive electrode metal foil (for example, an aluminum foil) 21 and a positive electrode active material layer 22 containing a positive electrode active material on both surfaces of the positive electrode metal foil 21. In the positive electrode 20, when one edge part of the edge part along a pair of long sides is made into the 1st edge part 20a, the positive electrode 20 has the positive electrode tab 23 of the shape protruded from the 1st edge part 20a. Have. The positive electrode tab 23 is a portion constituted by the positive electrode metal foil 21 itself without the positive electrode active material layer 22 in the positive electrode metal foil 21.

  In the present embodiment, the side along the first edge 20 a is one side of the positive electrode 20. Moreover, in the positive electrode 20, the edge part along the other long side which becomes the other side of the 1st edge part 20a is made into the 2nd edge part 20b, and the 1st edge part 20a and the 2nd edge part 20b are connected. Edge portions along the pair of short sides are respectively referred to as third edge portions 20c.

  The negative electrode 40 has a rectangular sheet-like negative electrode metal foil (for example, copper foil) 41 and a negative electrode active material layer 42 containing a negative electrode active material on both surfaces of the negative electrode metal foil 41. In the negative electrode 40, when the edge along one long side of the pair of long sides is a first edge 40a, the negative electrode 40 has a negative electrode tab 43 protruding from the first edge 40a. Have. The negative electrode tab 43 is a portion formed of the negative electrode metal foil 41 itself without the negative electrode active material layer 42 in the negative electrode metal foil 41. In the present embodiment, the side along the first edge portion 40 a is one side of the negative electrode 40. Moreover, in the negative electrode 40, the edge part along the other long side which is the other side of the 1st edge part 40a is made into the 2nd edge part 40b, and the 1st edge part 40a and the 2nd edge part 40b are connected. Edge portions along the pair of short sides are respectively referred to as third edge portions 40c.

  The length of the first edge 40 a of the negative electrode 40 is longer than the length of the first edge 20 a of the positive electrode 20, and the length of the second edge 40 b of the negative electrode 40 is the length of the positive electrode 20. It is longer than the length of the second edge 20b. Further, the length of the third edge 40 c of the negative electrode 40 is longer than the length of the third edge 20 c of the positive electrode 20. Therefore, the negative electrode 40 is slightly larger than the positive electrode 20.

  The electrode assembly 12 is configured by laminating a positive electrode tab group 23 a configured by stacking the positive electrode tab 23 and a negative electrode tab 43 on the tab side end surface 12 a facing the inner surface of the lid 14. A negative electrode tab group 43a. The positive electrode tab group 23a and the negative electrode tab group 43a are formed by collecting the positive electrode tab 23 and the negative electrode tab 43 at one end in the stacking direction of the electrode assembly 12 and then folding them back toward the other end in the stacking direction. The positive electrode tab group 23a is electrically connected to the positive electrode conductive member 15a, and the negative electrode tab group 43a is electrically connected to the negative electrode conductive member 16a.

  The electrode storage separator 30 includes rectangular sheet-like separator members 31 that face each other. Each separator member 31 is made of an insulating resin (for example, polyethylene). The two separator members 31 have the same shape and the same size, and are slightly larger than the positive electrode 20.

  Each separator member 31 has a first protruding portion 31 a that protrudes from the first edge portion 20 a of the positive electrode 20 in the protruding direction of the positive electrode tab 23 in a state where the positive electrode 20 is overlapped. Each separator member 31 has a second protruding portion 31 b that protrudes from three sides along the second edge 20 b and the pair of third edges 20 c of the positive electrode 20. The electrode storage separator 30 is formed by joining the first protruding portions 31a of the separator member 31 and the second protruding portions 31b. The electrode storage separator 30 includes a bottom edge 30a at a portion of the second protruding portion 31b where the portions along the second edge 20b are joined.

  The electrode assembly 12 includes a bottom surface 12 b on the end surface of the case main body 13 on the inner bottom surface 13 b side. The bottom surface 12 b is configured by laminating the bottom edge 30 a of the electrode storage separator 30 and the second edge 40 b of the negative electrode 40. The bottom edge 30a of the electrode storage separator 30 and the second edge 40b of the negative electrode 40 are located on the same plane. The electrode assembly 12 includes side surfaces 12 c on four end surfaces of the case main body 13 on the four side wall 13 c sides.

  As shown in FIGS. 1 and 3, the secondary battery 10 includes an insulating sheet 50 that insulates the electrode assembly 12 from the case body 13. The insulating sheet 50 includes two sheets (a first sheet 51 and a second sheet 52). The first sheet 51 and the second sheet 52 are sheets manufactured from the same resin. The insulating sheet 50 includes a bottom surface covering portion 50 a that covers the entire bottom surface 12 b of the electrode assembly 12 and a cylindrical side surface covering portion 50 b that covers the four side surfaces 12 c of the electrode assembly 12. The bottom surface covering portion 50 a is composed of the first sheet 51 and the second sheet 52, and the side surface covering portion 50 b is composed of the second sheet 52. The bottom surface covering portion 50a has a thick portion 53 formed by overlapping the first sheet 51 and the second sheet 52.

  The 1st sheet | seat 51 is arrange | positioned so that the bottom face 12b of the electrode assembly 12 may be covered, and comprises the bottom face cover part 50a. The size of the first sheet 51 is the same as the size of the bottom surface 12 b of the electrode assembly 12. The surface of the first sheet 51 on the electrode assembly 12 side is an adhesive surface 51a having adhesiveness. The first sheet 51 is bonded to the bottom surface 12b of the electrode assembly 12 by the adhesive surface 51a.

  The second sheet 52 is disposed so as to cover the bottom surface 12 b and the four side surfaces 12 c of the electrode assembly 12. The second sheet 52 includes a first part 52 a that covers the bottom surface 12 b of the electrode assembly 12 whose bottom surface 12 b is covered by the first sheet 51, and a second part 52 b that covers the four side surfaces 12 c of the electrode assembly 12. . The first part 52a has a rectangular shape, and the second part 52b stands from each edge of the first part 52a. The second portion 52b is located between the four side surfaces 12c of the electrode assembly 12 and the four side walls 13c of the case main body 13, and the first portion 52a includes the first sheet 51 and the inner bottom surface 13b of the case main body 13. Located between. The 1st site | part 52a comprises the bottom face cover part 50a with the 1st sheet | seat 51, and the 2nd site | part 52b comprises the side surface cover part 50b. The second sheet 52 is formed by folding a single insulating film into a bottomed rectangular tube, and the portions that overlap each other as a result of the bending are pasted by the tape 54 along the side surface 12c of the electrode assembly 12. It is attached.

  The thick portion 53 is a portion where the first portion 51 a of the first sheet 51 and the second sheet 52 overlaps, and exists so as to cover the entire bottom surface 12 b of the electrode assembly 12. The thickness of the bottom surface covering portion 50a is thicker than the thickness of the side surface covering portion 50b composed of only the second sheet 52. The electrode assembly 12 is supported on the thick portion 53.

Next, the effect of the first embodiment will be described together with the action.
(1) A thick portion 53 is interposed between the bottom surface 12 b of the electrode assembly 12 and the inner bottom surface 13 b of the case body 13. The thick part 53 is thicker than the side cover part 50b, and even if it contacts the inner bottom surface 13b of the case body 13 due to vibration during use of the secondary battery 10, it is difficult to break. In addition, while forming the thick portion 53 in the bottom surface covering portion 50a, the side surface covering portion 50b covering the side surface 12c of the electrode assembly 12 is thinned so that the electrode housing separator 30 and the negative electrode that can be accommodated in the case body 13 There is no need to reduce the number of electrodes 40. Therefore, it is possible to suppress a short circuit between the bottom surface 12b of the electrode assembly 12 and the inner bottom surface 13b of the case body 13 without reducing the capacity of the secondary battery 10.

  (2) Since the thick part 53 is configured by stacking the two insulating sheets 50 (the first sheet 51 and the second sheet 52), the thick part 53 and the thick part 53 are formed on one insulating film. The thick part 53 can be manufactured more easily than manufacturing a thin part.

  (3) The surface of the first sheet 51 on the electrode assembly 12 side is an adhesive surface 51a. For this reason, even if a part of the electrode assembly 12 (for example, the negative electrode active material layer 42) drops and foreign matter is generated when the secondary battery 10 is used, the foreign matter adheres to the adhesive surface 51 a of the first sheet 51. . Therefore, it is possible to suppress foreign matter from being scattered in the secondary battery 10.

  (4) The size of the first sheet 51 is the same as the size of the bottom surface 12 b of the electrode assembly 12. For this reason, the size of the thick portion 53 (the portion where the first sheet 51 and the second sheet 52 overlap) and the size of the bottom surface 12b of the electrode assembly 12 can be made the same. Therefore, no matter which part of one of the first portions 52a of the first sheet 51 and the second sheet 52 constituting the bottom cover 50a is torn, the other sheet insulates the electrode assembly 12 from the case body 13. The state can be maintained, and a short circuit between the electrode assembly 12 and the case body 13 can be further suppressed.

(5) Since the first sheet 51 and the second sheet 52 are manufactured from the same resin, it is not necessary to prepare the material of the first sheet 51 and the material of the second sheet 52 separately.
(Second Embodiment)
Hereinafter, a second embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS. 4 and 5. In addition, since the structure of case 11 and the electrode assembly 12 is the same structure as 1st Embodiment, description is abbreviate | omitted.

  As shown in FIGS. 4 and 5, the secondary battery 10 includes an insulating sheet 60 that insulates the electrode assembly 12 from the case body 13. The insulating sheet 60 includes two sheets (a first sheet 61 and a second sheet 62). The first sheet 61 and the second sheet 62 are sheets manufactured from the same resin. The insulating sheet 60 includes a bottom surface covering portion 60 a that covers the entire bottom surface 12 b of the electrode assembly 12 and a cylindrical side surface covering portion 60 b that covers the four side surfaces 12 c of the electrode assembly 12. The bottom surface covering portion 50 a is composed of the first sheet 51 and the second sheet 52, and the side surface covering portion 50 b is composed of the second sheet 52. The bottom surface covering portion 60a has a thick portion 63 formed by overlapping the first sheet 61 and the second sheet 62.

  The second sheet 62 is disposed so as to cover the bottom surface 12 b and the four side surfaces 12 c of the electrode assembly 12. The second sheet 62 includes a first portion 62 a that covers the bottom surface 12 b of the electrode assembly 12 and a second portion 62 b that covers the four side surfaces 12 c of the electrode assembly 12. The first portion 62a has a rectangular shape, and the second portion 62b stands from each edge of the first portion 62a. The 1st site | part 62a comprises the bottom face cover part 60a, and the 2nd site | part 62b comprises the side surface cover part 60b. The second sheet 62 is formed by folding a single insulating film into a bottomed rectangular tube shape, and the portions that overlap each other by bending are pasted by the tape 64 so as to be along the side surface 12c of the electrode assembly 12. It is attached. The bottom surface 12 b of the electrode assembly 12 is in contact with the first portion 62 a of the second sheet 62.

  The first sheet 61 is disposed so as to cover the bottom surface 12b of the electrode assembly 12 covered by the first portion 62a of the second sheet 62, and constitutes a bottom surface covering portion 60a. The size of the first sheet 61 is the same as the size of the inner bottom surface 13 b of the case body 13. The first sheet 61 is located between the first portion 62 a of the second sheet 62 and the inner bottom surface 13 b of the case body 13. The first portion 62 a of the second sheet 62 is located between the bottom surface 12 b of the electrode assembly 12 and the first sheet 61, and the second portion 62 b includes the four side surfaces 12 c of the electrode assembly 12 and the case body 13. It is located between the four side walls 13c.

  The thick portion 63 is a portion where the first portion 62 a of the second sheet 62 and the first sheet 61 overlap, and exists so as to cover the entire bottom surface 12 b of the electrode assembly 12. Therefore, the thickness of the thick portion 63 is thicker than the thickness of the side surface covering portion 60b configured by only the second sheet 62. The electrode assembly 12 is supported on the thick portion 63.

Next, effects of the second embodiment will be described together with actions.
(6) A thick portion 63 is interposed between the bottom surface 12 b of the electrode assembly 12 and the inner bottom surface 13 b of the case body 13. The thick part 63 is thicker than the side cover part 60b, and even if it contacts the inner bottom surface 13b of the case body 13 due to vibration during use of the secondary battery 10, it is difficult to break. In addition, while forming the thick portion 63 on the bottom surface covering portion 60a, the side surface covering portion 60b that covers the side surface 12c of the electrode assembly 12 is thinned, so that the electrode storage separator 30 and the negative electrode that can be accommodated in the case body 13 There is no need to reduce the number of electrodes 40. Therefore, it is possible to suppress a short circuit between the bottom surface 12b of the electrode assembly 12 and the inner bottom surface 13b of the case body 13 without reducing the capacity of the secondary battery 10.

  (7) Since the thick portion 63 is configured by stacking the two insulating sheets 60 (the first sheet 61 and the second sheet 62), the thick portion 63 and the thick portion 63 are formed on one insulating film. The thick part 63 can be manufactured more easily than manufacturing a thin part. Further, if the first sheet 61 is disposed on the inner bottom surface 13 b of the case body 13 before the electrode assembly 12 covered with the second sheet 62 is accommodated in the case body 13, the electrode assembly 12 and the second sheet are arranged. When 62 is accommodated in the case body 13, the thick portion 63 can be formed.

  (8) The size of the first sheet 61 is the same as the size of the inner bottom surface 13 b of the case body 13. For this reason, the size of the thick portion 63 (the portion where the first sheet 61 and the second sheet 62 overlap) can be made the same as the size of the inner bottom surface 13 b of the case body 13 which is larger than the bottom surface 12 b of the electrode assembly 12. Therefore, no matter which part of one of the first portions 52a of the first sheet 51 and the second sheet 52 constituting the bottom cover 50a is torn, the other sheet insulates the electrode assembly 12 and the case body 13 from each other. The state can be maintained. Moreover, since the thickness part 63 can be enlarged compared with the case where the magnitude | size of the 1st sheet | seat 61 is made the same as the magnitude | size of the bottom face 12b of the electrode assembly 12, the short circuit with the electrode assembly 12 and the case main body 13 can be suppressed more. . Moreover, since the magnitude | size of the 1st sheet | seat 61 can be determined according to the inner bottom face 13b of the case main body 13 which is a rigid body, the 1st sheet | seat 61 can be manufactured easily.

(9) Since the first sheet 61 and the second sheet 62 are manufactured from the same resin, it is not necessary to prepare the material of the first sheet 61 and the material of the second sheet 62 separately.
(Third embodiment)
Hereinafter, a third embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS. 6 and 7. In addition, since the structure of case 11 and the electrode assembly 12 is the same structure as 1st Embodiment, description is abbreviate | omitted.

  As shown in FIGS. 6 and 7, the secondary battery 10 includes a single insulating sheet 70 made of resin that insulates the electrode assembly 12 and the case body 13. The insulating sheet 70 is disposed so as to cover the entire bottom surface 12 b and the four side surfaces 12 c of the electrode assembly 12. The insulating sheet 70 includes a bottom surface covering portion 70 a that covers the entire bottom surface 12 b of the electrode assembly 12 and a cylindrical side surface covering portion 70 b that covers the four side surfaces 12 c of the electrode assembly 12. The bottom surface covering portion 70 a is composed of a first portion 71 that covers the entire bottom surface 12 b of the electrode assembly 12, and the side surface covering portion 70 b is composed of a second portion 72 that covers the four side surfaces 12 c of the electrode assembly 12. . The first part 71 has a rectangular shape, and the second part 72 is erected from each edge of the first part 71. The bottom surface cover portion 70a has a thick portion 73 that is thicker than the thickness of the side surface cover portion 70b. In the present embodiment, the entire thickness of the bottom cover 70a is thicker than that of the side cover 70b. That is, the entire bottom surface covering portion 70 a is the thick portion 73. The electrode assembly 12 is supported on the thick portion 73. The insulating sheet 70 is formed by folding a single insulating film into a rectangular tube with a bottom, and the portions overlapping each other by bending are pasted along the side surface 12c of the electrode assembly 12 with a tape 74. It has been.

Next, effects of the third embodiment will be described together with actions.
(10) A thick portion 73 is interposed between the bottom surface 12 b of the electrode assembly 12 and the inner bottom surface 13 b of the case body 13. The thick part 73 is thicker than the side cover part 70b, and even if it contacts the inner bottom surface 13b of the case body 13 due to vibration during use of the secondary battery 10, it is difficult to break. In addition, while forming the thick portion 73 on the bottom surface covering portion 70a, the side surface covering portion 70b that covers the side surface 12c of the electrode assembly 12 is thinned so that the electrode housing separator 30 and the negative electrode that can be accommodated in the case body 13 There is no need to reduce the number of electrodes 40. Therefore, it is possible to suppress a short circuit between the bottom surface 12b of the electrode assembly 12 and the inner bottom surface 13b of the case body 13 without reducing the capacity of the secondary battery 10.

  (11) Since the entire first portion 71 is thicker than the second portion 72, the entire bottom surface covering portion 70a of the insulating sheet 70 can be hardly broken. Therefore, a short circuit between the electrode assembly 12 and the case body 13 can be further suppressed.

In addition, you may change the 1st-3rd embodiment as follows.
The positive electrode 20 may have a structure in which the positive electrode active material layer 22 exists on one side of the positive electrode metal foil 21. Similarly, the negative electrode 40 may have a configuration in which the negative electrode active material layer 42 exists on one surface of the negative electrode metal foil 41.

  The electrode assembly 12 has a structure in which the electrode storage separators 30 that store the positive electrodes 20 and the negative electrodes 40 are alternately stacked, but the plurality of positive electrodes 20 and the plurality of negative electrodes 40 are interposed via the separators. A structure in which layers are alternately stacked may be used.

  The positive electrode 20 may include a portion where the positive electrode active material layer 22 does not exist other than the positive electrode tab 23. Similarly, the negative electrode 40 may include a portion where the negative electrode active material layer 42 does not exist other than the negative electrode tab 43.

  The positive electrode metal foil 21 is not limited to an aluminum foil, and may be another metal foil that can form the positive electrode 20. Similarly, the negative electrode metal foil 41 is not limited to a copper foil, and may be another metal foil that can form the negative electrode 40.

  In the above embodiment, the positive electrode terminal 15 and the positive electrode conductive member 15a are integrated, but may be configured separately. Similarly, although the negative electrode terminal 16 and the negative electrode conductive member 16a are integrated, you may make it another structure.

The insulating sheets 50, 60, 70 need not be made of resin as long as they are non-conductive materials.
The material of the first sheet 51 may be a material different from the material of the second sheet 52. Further, the material of the first sheet 61 may be a material different from the material of the second sheet 62.

  The size of the first sheet 51 of the first embodiment may be smaller than the bottom surface 12 b of the electrode assembly 12. In this case, the size of the thick portion 53 (the portion where the first sheet 51 and the second sheet 52 overlap) in the bottom surface covering portion 50a is reduced. Similarly, the size of the first sheet 61 of the second embodiment may be smaller than the inner bottom surface 13 b of the case body 13. In this case, the size of the thick portion 63 (the portion where the first sheet 61 and the second sheet 62 overlap) in the bottom surface covering portion 60a is reduced. In addition, if the magnitude | size of the thick parts 53 and 63 in the bottom face cover parts 50a and 60a is made more than half the magnitude | size of the bottom face 12b of the electrode assembly 12, the shakiness of the electrode assembly 12 can be suppressed.

  In the third embodiment, a part of the bottom cover 70a may be thicker than the side cover 70b. In this case, the size of the thick portion 73 in the bottom surface covering portion 70a is reduced. In addition, if the size of the thick portion 73 is set to be half or more of the size of the bottom surface 12b of the electrode assembly 12, the rattling of the electrode assembly 12 can be suppressed.

  In the first to third embodiments, the side surface covering portion 50b covers the four side surfaces 12c of the electrode assembly 12, but if the side surface portion 50b covers the side surface as an end surface in the stacking direction of the electrode assembly 12, The four side surfaces 12c may not be covered. However, the side surface not covered by the side surface covering portion 50b needs to be insulated from the case body 13 by, for example, disposing an insulating sheet or forming a film on the inside of the side wall 13c of the case body 13. There is.

  The portions overlapped by bending in the insulating sheets 50, 60, and 70 were attached to the side surface 12c of the electrode assembly 12 by the tapes 54, 64, and 74, but the overlapped portions may be heat-welded.

  The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, any ion may be used as long as ions move between the active material for the positive electrode and the active material for the negative electrode and charge is transferred.

  The power storage device can also be applied to power storage devices other than secondary batteries, such as capacitors.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as an electrical storage device, 11 ... Case, 12 ... Electrode assembly, 12b ... Bottom surface, 13 ... Case main body, 13b ... Inner bottom surface, 20 ... Positive electrode, 40 ... Negative electrode, 50, 60, 70 ... Insulating sheet, 50a, 60a, 70a ... bottom cover, 50b, 60b, 70b ... side cover, 51, 61 ... first sheet, 51a ... adhesive surface, 52, 62 ... second sheet, 53, 63, 73 ... Thick part.

Claims (7)

An electrode assembly having a plurality of positive electrodes and a plurality of negative electrodes;
A bottomed cylindrical case for housing the electrode assembly;
A power storage device comprising an insulating sheet that insulates the electrode assembly from the case,
The insulating sheet includes a bottom surface covering portion interposed between an inner bottom surface of the case and a bottom surface of the electrode assembly, and a side surface covering portion covering a side surface of the electrode assembly,
The power storage device, wherein the bottom surface covering portion has a thick portion thicker than a thickness of the side surface covering portion. The insulating sheet includes a first sheet that constitutes the bottom face cover, and a second sheet that constitutes the bottom face cover and the side face cover,
The first sheet is located between a bottom surface of the electrode assembly and the second sheet,
The power storage device according to claim 1, wherein the thick portion is configured by overlapping the first sheet and the second sheet.   The power storage device according to claim 2, wherein a surface of the first sheet on the electrode assembly side is an adhesive surface.   The power storage device according to claim 2 or 3, wherein a size of the first sheet is the same as a size of a bottom surface of the electrode assembly. The insulating sheet includes a first sheet that constitutes the bottom face cover, and a second sheet that constitutes the bottom face cover and the side face cover,
The first sheet is located between the second sheet and the inner bottom surface of the case,
The power storage device according to claim 1, wherein the thick portion is configured by overlapping the first sheet and the second sheet.   The power storage device according to claim 5, wherein a size of the first sheet is the same as a size of an inner bottom surface of the case. The power storage device according to any one of claims 2 to 6, wherein a material of the first sheet is the same as a material of the second sheet.

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