JP2016115407A - Power storage element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve higher capacity of a power storage element in which an insulation sheet is interposed between a wound type electrode body and an inner surface of an exterior body.SOLUTION: A power storage element 1 includes: an electrode body 20 having curved parts 20d; an exterior body 10 which has facing surface parts 11d each facing the curved part 20d and houses the electrode body 20 therein; and an insulation sheet 30 which has thick wall parts 36 in each of which two sheet parts 32a, 32b overlap with each other, and which is arranged between the electrode body 20 and the inner surface of the exterior body 10. The thick wall part 36 is arranged oppositely to the curved part 20d at a position shifted in a circumferential direction of the curved part 20d from the closest-approaching part 20e of the curved part 20d to the facing surface part 11d.SELECTED DRAWING: Figure 15

Description

  The present invention relates to a power storage element including a nonaqueous electrolyte secondary battery such as a lithium ion secondary battery.

  A power storage element including a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery may be provided with a so-called wound electrode body. The wound electrode body is wound into a high flattened elliptic cylinder so that a pair of curved portions are formed by overlapping a positive electrode sheet, a negative electrode sheet, and two separators, each of which is a belt shape. It is a turn.

  As disclosed in Patent Document 1, a wound-type electrode body may be accommodated in a flat, rectangular parallelepiped metal exterior body covered with an insulating sheet. Short circuit prevention with an exterior body is achieved.

  Generally, as the insulating sheet, a sheet that is formed into a flat box shape or a cylindrical shape so that one sheet can be disposed between the electrode body and the exterior body is used. Specifically, when the insulating sheet is formed into a box shape, for example, a pair of rising parts are formed by bending both side parts sandwiching the part arranged along the bottom part of the exterior body, A box-shaped insulating sheet is formed by joining the side edges of the rising portions of the two. In addition, when the insulating sheet is formed into a cylindrical shape, the strip-shaped sheet is curved into a cylindrical shape so that both end portions in the longitudinal direction overlap each other, and the overlapped end portions are joined to each other, thereby forming the cylindrical insulating sheet Is formed.

  In the battery disclosed in Patent Document 1, the electrode body is accommodated in the exterior body in such a posture that the winding shaft extends in the horizontal direction along the long side surface of the exterior body. Thereby, the end surface portion of the electrode body is disposed to face the short side surface of the exterior body. The insulating sheet includes a pair of rising portions arranged along the long side surface of the exterior body, and both side edges of each rising portion are bent so as to be disposed along the short side surface of the exterior body. The two sheet portions arranged along the short side surface of the exterior body are joined to each other, thereby forming a box-shaped insulating sheet having a shape along the inner surface of the exterior body.

JP 2011-155001 A

  By the way, in a power storage element including a wound electrode body, the gap between the inner surface of the exterior body is made as small as possible under the dimensional restriction that the electrode body is accommodated in the exterior body of a rectangular parallelepiped having a predetermined dimension. Thus, it is required to increase the capacity by forming and arranging the electrode body.

  However, in the electric storage element disclosed in Patent Document 1, a joint portion of the insulating sheet is interposed between the end surface portion of the electrode body and the short side surface of the exterior body. In the joint portion, the thickness is increased by overlapping two sheet portions. For this reason, the restriction that the thick joint portion is accommodated between the end face portion of the electrode body and the short side surface of the exterior body limits the increase in size of the electrode body, and the capacity of the power storage element cannot be sufficiently increased.

  As described above, in the conventional power storage element in which the insulating sheet is interposed between the wound electrode body and the exterior body, including the power storage element of Patent Document 1, the insulating sheet is used while increasing the capacity of the power storage element. There is no special consideration for the installation.

  Accordingly, an object of the present invention is to increase the capacity of a power storage element in which an insulating sheet is interposed between a wound electrode body and an inner surface of an exterior body.

The present invention
An electrode body having a curved portion;
An exterior body having an opposing surface portion facing the curved portion and containing the electrode body;
An insulating sheet disposed between the electrode body and the inner surface of the exterior body, having a thick part where two sheet parts overlap;
The thick-walled portion provides a power storage element that is disposed to face the bending portion at a position that is shifted in the circumferential direction of the bending portion from the closest portion of the bending portion to the facing surface portion.

The present invention also provides:
An electrode body having a curved portion;
An exterior body having an opposing surface portion facing the curved portion and containing the electrode body;
An insulating sheet disposed between the electrode body and the inner surface of the exterior body,
The thickest portion of the insulating sheet having the largest thickness is disposed opposite to the bending portion at a position shifted in the circumferential direction of the bending portion from the closest portion of the bending portion to the facing surface portion. provide.

  According to these power storage elements, the thick portion of the insulating sheet is not interposed in the gap portion where the distance between the curved portion of the electrode body and the facing surface portion of the exterior body is minimized, so that the bending portion and the facing surface portion It is possible to place the curved portion close to the facing surface portion so that the distance is smaller than the thickness of the thick portion. In addition, since the thick part of the insulating sheet is arranged opposite to the curved part of the electrode body, the part other than the curved part of the electrode body is placed close to the inner surface of the exterior body without interposing the thick part. can do. By minimizing the distance between the inner surface of the exterior body and the electrode body in this manner, the size of the electrode body can be increased, thereby increasing the capacity of the power storage element.

  According to the electricity storage device according to the present invention, it is possible to increase the capacity of the electricity storage device while preventing a short circuit between the exterior body and the electrode body by the insulating sheet.

The longitudinal cross-sectional view of the nonaqueous electrolyte secondary battery which concerns on 1st Embodiment of this invention. The disassembled perspective view of the nonaqueous electrolyte secondary battery of FIG. The perspective view of an electrode body. The expanded view of an electrode body. The enlarged view of the part V of FIG. The enlarged view of the part VI of FIG. The perspective view of an electrode body and a collector. The partially broken partial perspective view of the nonaqueous electrolyte secondary battery of FIG. The partially broken decomposition | disassembly side view of the nonaqueous electrolyte secondary battery of FIG. The perspective view of the assembly body containing an electrode body and an insulating sheet. The perspective view of the insulating sheet seen from diagonally downward. FIG. FIG. 3 is a cross-sectional view of the nonaqueous electrolyte secondary battery broken along line XIII-XIII in FIG. 1. The enlarged view of the part XIV of FIG. The partially broken perspective view which shows a part of nonaqueous electrolyte secondary battery containing the part XIV of FIG. The expanded cross-sectional view similar to FIG. 14 which shows the modification of an insulating sheet. The perspective view of the assembly body and insulating sheet of the nonaqueous electrolyte secondary battery which concern on 2nd Embodiment of this invention. The expanded cross-sectional view similar to FIG. 14 of the nonaqueous electrolyte secondary battery of FIG.

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, terms including “up”, “down”, “side”, “end”) are used as necessary. Is for facilitating understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

[First Embodiment]
1 and 2 show a lithium ion secondary battery (hereinafter simply referred to as “battery”) 1 according to a first embodiment of the present invention.

[overall structure]
1 and 2, the battery 1 includes an outer package 10, an electrode body 20, an insulating sheet 30, a bottom spacer 40, positive and negative external terminals 50A and 50B, positive and negative current collectors 60A and 60B, an upper packing. 70A, 70B, lower packings 80A, 80B, and an upper spacer 90 are provided.

  The exterior body 10 includes a case main body 11 and a lid 12 that closes the opening 11 a of the case main body 11. In the present embodiment, the case body 11 and the lid 12 are made of aluminum or an aluminum alloy. The case body 11 includes a rectangular plate-like bottom wall portion 11b, a pair of long side wall portions 11c rising from the long side of the bottom wall portion 11b, and a pair of short side wall portions 11d rising from the short side of the bottom wall portion 11b. The lid 12 has a generally rectangular plate shape. Upper ends of the long side wall portion 11 c and the short side wall portion 11 b define an opening 11 a of the case main body 11. An electrode body 20 is accommodated in the case body 11 filled with the electrolytic solution. The electrode body 20 is covered with an insulating sheet 30. A bottom spacer 40 is interposed between the electrode body 20 and the bottom wall portion 11 b of the case body 11. The lower packings 80 </ b> A and 80 </ b> B and the upper spacer 90 are also accommodated in the case body 11. The lid 12 is provided with a safety valve 13 for discharging the gas generated in the case body 11 to the outside of the exterior body 10.

  Referring to FIGS. 3 and 4 together, the electrode body 20 includes a positive electrode sheet 21, a negative electrode sheet 22, and two separators 23 made of a microporous resin sheet. 23 are overlapped and wound into an elliptical shape having a generally high flatness. One of the two separators 23 and 23 is interposed between one layer of the positive electrode sheet 21 and one layer of the negative electrode sheet 22 adjacent thereto. The separator 23 is longer than the positive electrode sheet 21 and the negative electrode sheet 22. Thereby, the outermost layer of the electrode body 20 is comprised by the separator 23 (refer FIG. 14).

  The winding axis (winding axis) of the positive electrode sheet 21, the negative electrode sheet 22, and the two separators 23, 23 is conceptually indicated by the symbol A in FIG. The electrode body 20 is accommodated in the case main body 11 in such a posture that the winding axis A extends in a direction in which the bottom wall portion 11b of the case main body 11 and the opening 11a face each other (vertical direction in FIG. 1).

  As shown in FIG. 3, each end portion of the electrode body 20 in the extending direction of the winding axis A is an end surface portion where the end portions in the width direction of the positive electrode sheet 21, the negative electrode sheet 22 and the separators 23, 23 are arranged. 20a and 20b. The electrode body 20 is disposed so as to face the winding axis A, and a pair of straight portions 20c, 20c extending linearly parallel to each other when viewed from the direction in which the winding axis A extends, and from the direction in which the winding axis A extends. A pair of curved portions 20d and 20d extending so as to connect the pair of straight portions 20c and 20c while being bent in a semicircular shape as viewed.

  The straight line portion 20c is a portion that extends linearly in design. In a state where the electrode body 20 is actually accommodated in the exterior body 10, the straight portion 20c is not necessarily arranged in a completely straight shape, but is bent so as to have a shape close to a straight line as a whole. May be arranged.

  The positive electrode sheet 21 includes a strip-shaped positive metal foil 24 and a positive electrode active material layer 25 formed on both surfaces of the positive metal foil 24. The positive electrode active material layer 25 is provided up to the side edge of the positive electrode metal foil 24 at one end (the lower side in FIGS. 3 and 4) in the width direction of the positive electrode sheet 21. At the other end in the width direction of the positive electrode sheet 21 (upper side in FIGS. 3 and 4), an uncoated portion 24a in which the positive electrode metal foil 24 is exposed is provided without providing the positive electrode active material layer 25. ing.

  The negative electrode sheet 22 includes a strip-shaped negative electrode metal foil 26 and negative electrode active material layers 27 formed on both surfaces of the negative electrode metal foil 26. At one end in the width direction of the negative electrode sheet 22 (lower side in FIGS. 3 and 4), the negative electrode active material layer 27 is provided up to the side edge of the negative electrode metal foil 26. At the other end in the width direction of the negative electrode sheet 22 (upper side in FIGS. 3 and 4), an uncoated portion 26a in which the negative electrode metal foil 26 is exposed without providing the negative electrode active material layer 27 is provided. ing. The width of the negative electrode sheet 22 is larger than the width of the positive electrode sheet 21, and the width of the separator 23 is larger than the width of the negative electrode sheet 22.

  The positive electrode metal foil 24 is provided with a plurality of protrusions 24 b protruding outward in the width direction from the uncoated part 24 a with a gap in the longitudinal direction. In a state in which the positive electrode sheet 21, the negative electrode sheet 22, and the separators 23 and 23 are overlapped and wound, a tab-like portion (positive electrode current collecting tab 28) in which a plurality of protrusions 24b are overlapped with each other and protrude from the electrode body 20. ) Is formed. The negative electrode metal foil 26 is also provided with a plurality of protrusions 26b similar to the protrusions 24b of the positive electrode metal foil 24. The negative electrode current collector protruding from the electrode body 20 by overlapping these protrusions 26b. Tabs 29 are formed.

  Referring to FIG. 3, the positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 protrude from one end portion 20 a (the upper end portion in FIG. 3) of the electrode body 20. Also, one side of the pair of straight portions 20c, 20c (front side in FIG. 3) with respect to the center line B in the longitudinal direction when the end portion 20a of the electrode body 20 is viewed from the direction in which the winding axis A extends. Thus, the positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 protrude.

  A positive external terminal 50A is disposed on one end side (left side in FIG. 1) of the lid 12, and a negative external terminal 50B is disposed on the other end side (right side in FIG. 1). The external terminals 50 </ b> A and 50 </ b> B include plate-like portions 51 </ b> A and 51 </ b> B disposed on the outer side surface (upper side surface) 12 a of the lid 12. A connecting member such as a bus bar is welded to the plate-like portions 51A and 51B and connected to an external circuit.

  Referring to FIG. 5 in addition to FIGS. 1 and 2, the positive external terminal 50A includes a plate-like portion 51A disposed on the outer surface 12a of the lid 12, and a cylindrical shape protruding downward from the lower surface of the plate-like portion 51A. The shaft part 52 is provided. The plate-like portion 51A and the shaft portion 52 are integrally formed. The shaft portion 52 penetrates the lid 12 and projects into the case main body 11.

  An enlarged diameter portion 52 a is provided at the lower end of the shaft portion 52 of the positive external terminal 50 </ b> A, whereby the positive external terminal 50 </ b> A is crimped and fixed to the lid 12. Specifically, between the plate-like portion 51A and the enlarged diameter portion 52a of the external terminal 50A, the upper packing 70A made of insulating resin, the lid 12, the lower packing 80A made of insulating resin, and the positive electrode current collector 60A ( A positive external terminal 50 </ b> A and a current collector 60 </ b> A are fixed to the lid 12 by sandwiching a to-be-clamped portion 62 </ b> A) described later. An upper packing 70A is interposed between the outer surface 12a of the lid 12 and the external terminal 50A, and a lower packing 80A is interposed between the inner surface (lower surface) 12b of the lid 12 and the current collector 60A. ing. In the present embodiment, the positive external terminal 50 and the current collector 60A are made of aluminum or an aluminum alloy.

  Referring to FIG. 6 in addition to FIGS. 1 and 2, the negative external terminal 50B includes a plate-like portion 51B disposed on the outer surface 12a of the lid 12, and a rivet 53 separate from the plate-like portion 51B. . The jaw 53a at the upper end of the rivet 53 is press-fitted into the through-hole formed in the plate-like portion 51B, whereby the rivet 53 is fixed to the plate-like portion 51B. The rivet 53 protrudes downward from the lower surface of the plate-like portion 51 </ b> B, penetrates the lid 12, and protrudes into the case body 11.

  An enlarged diameter portion 53 b is provided at the lower end of the rivet 53 of the negative external terminal 50 </ b> A, whereby the negative external terminal 50 </ b> B is crimped and fixed to the lid 12. Specifically, the upper packing 70B made of insulating resin, the lid 12, the lower packing 80B made of insulating resin, and the negative electrode current collector 60B are disposed between the plate-like portion 51B and the enlarged diameter portion 53b of the external terminal 50B. The negative external terminal 50B and the current collector 60B are fixed to the lid 12 by being sandwiched. An upper packing 70B is interposed between the outer surface 12a of the lid 12 and the external terminal 50B, and a lower packing 80B is interposed between the inner surface 12b of the lid 12 and the negative electrode current collector 60B. In this embodiment, the negative external terminal 50B is made of a plate-like portion 51B aluminum or an aluminum alloy, and the rivet 53 is made of copper or a copper alloy. The negative electrode current collector 60B is made of copper or a copper alloy.

  As shown most clearly in FIG. 7, the positive electrode current collector 60A includes a welded portion 61A and a crimped portion 62A. The welded portion 61A is welded to the positive electrode current collecting tab 28 of the electrode body 20, and is electrically and mechanically connected. As described above, the crimped portion 62A is crimped and fixed to the lid 12 by the enlarged diameter portion 52a formed in the shaft portion 52 of the positive external terminal 50A. Similarly, the negative electrode current collector 60B includes a welded portion 61B and a crimped portion 62B. The welded portion 61B is welded to the negative electrode current collecting tab 29 of the electrode body 20, and is electrically and mechanically connected. As described above, the crimped portion 62B is crimped and fixed to the lid 12 by the enlarged diameter portion 53b formed on the rivet 53 of the negative external terminal 50B.

  As shown most clearly in FIGS. 8 and 9, an upper spacer 90 is interposed between the electrode body 20 and the inner side surface 12 b of the lid 12. The upper spacer 90 is provided with a current collector housing portion 92 for each of the current collectors 60A and 60B. The current collector housing part 92 includes a side wall part 92a, an upper wall part 92b extending from the upper end of the side wall part 92a, and a lower wall part 92c extending substantially parallel to the upper wall part 92b from the lower end of the side wall part 92a. A gap 92d is formed between the upper wall portion 92b and the lower wall portion 92c so as to open to the side opposite to the side wall portion 92a.

  As shown in FIG. 9, the positive current collector 60 </ b> A is inserted into the gap 92 d of the current collector housing portion 92 together with the folded positive current collector tab 28. Similarly, the negative electrode current collector 60 </ b> B is inserted into the gap 92 d of the current collector housing portion 92 together with the folded negative electrode current collector tab 29. Thus, the current collectors 60A and 60B are insulated from the lid 12 by the upper wall portion 92b of the upper spacer 90 and insulated from the electrode body 20 by the lower wall portion 92c of the upper spacer 90.

[Insulating sheet]
Hereinafter, the insulating sheet 30 and the configuration related thereto will be described in detail.

  As shown in FIGS. 10 and 11, the insulating sheet 30 is formed in a box shape so as to be disposed along the inner surface of the case body 11. The insulating sheet 30 includes a bottom surface portion 31 facing the bottom wall portion 11 b of the case body 11, first and second long side surface portions 32 and 33 facing each long side wall portion 11 c of the case body 11, and the case body 11. A pair of short side surface portions 38a and 38b facing each short side wall portion 11d is provided.

  The thickness of the insulating sheet 30 is preferably 20 μm or more and 200 μm or less. If the thickness of the insulating sheet 30 is less than 20 μm, the insulating function is likely to be impaired due to the damage of the insulating sheet 30, and if the thickness of the insulating sheet 30 is larger than 200 μm, the space for accommodating the electrode body 20 is reduced. Reduction of the capacity of the battery 1 is hindered.

  FIG. 12 is a development view of the insulating sheet 30 before assembly. As shown in FIG. 12, when the longitudinal direction of the bottom surface portion 31 in the developed state of the insulating sheet 30 is the first direction X and the short direction of the bottom surface portion 31 is the second direction Y, the bottom surface portion with respect to the second direction Y A pair of long side surface portions 32 and 33 are arranged on both sides of 31 adjacent to each other through boundary portions F1 and F2.

  With respect to the first direction X, projecting portions 34 projecting outward from the boundary portions F1, F2 with the long side surface portions 32, 33 are provided on both sides of the bottom surface portion 31. Each protrusion 34 is provided with folds F3 and F4 extending in the second direction Y.

  With respect to the first direction X in FIG. 12, on both sides of the first long side surface portion 32, first protruding portions 32 a that protrude outward from the boundary portion F <b> 1 with the bottom surface portion 31 are provided. On both sides, second projecting portions 33a projecting outward from the boundary portion F2 with the bottom surface portion 31 are provided. The protrusion amount of the second protrusion 33a is larger than the protrusion amount of the first protrusion 32a. A first seal portion 32c joined to the second projecting portion 33a is provided at the tip of each first projecting portion 32a, and a first joint joined to the first projecting portion 32a is provided at the tip of each second projecting portion 33a. Two seal portions 33c are provided.

  With respect to the second direction Y in FIG. 12, a third seal portion 32 e joined to one long side surface of the upper spacer 90 is provided at the end of the first long side surface portion 32 opposite to the bottom surface portion 31. A fourth seal portion 33e that is joined to the other long side surface of the upper spacer 90 is provided at the end of the second long side surface portion 33 opposite to the bottom surface portion 31.

  By the way, in the insulating sheet 30 in the unfolded state shown in FIG. 12, the second projecting portion 33 a projects more greatly in the first direction X than the first projecting portion 32 a and the projecting portion 34 of the bottom surface portion 31. Normally, such a developed shape is not adopted, but in this embodiment, in order to solve the new problem of increasing the capacity of the battery 1 by the configuration of the insulating sheet, the developed shape shown in FIG. 12 is adopted. Yes.

  The insulating sheet 30 shown in FIG. 12 is formed into a box shape as shown in FIGS. 10 and 11 by the following procedure.

  First, the first and second long side surface portions 32 and 33 are raised with respect to the bottom surface portion 31 by bending the insulating sheet 30 along the boundary portions F <b> 1 and F <b> 2 by valley folds at substantially right angles. Moreover, the front-end | tip part 34a of each protrusion part 34 is raised by bend | folding a pair of protrusion part 34 of the bottom face part 31 along the crease | folds F3 and F4 at substantially right angle, respectively.

  After the first and second long side surface portions 32 and 33 are raised with respect to the bottom surface portion 31, the pair of second projecting portions 33a are bent or bent inward, and the pair of first projecting portions 32a are disposed on the inner side. To form an overlap portion 36 in which the first seal portions 32c and the second seal portions 33c are overlapped with each other. Since the protruding amount of the second protruding portion 33a is larger than the protruding amount of the first protruding portion 32a, the overlap portion 36 has a distance from the first long side surface portion 32 as compared with the distance from the second long side surface portion 33. It is formed at a smaller position.

  In each overlap portion 36, the first and second seal portions 32c and 33c are joined to each other, thereby forming short side portions 38a and 38b including the first protrusion portion 32a and the second protrusion portion 33a. The first and second seal portions 32c and 33c may be joined by an arbitrary method, for example, by bonding using an adhesive or welding. By the above procedure, the box-shaped insulating sheet 30 shown in FIGS. 10 and 11 is formed.

  The electrode body 20 is covered with the insulating sheet 30 by inserting the assembly body 2 in which the electrode body 20 is assembled to a plurality of members including the lid 12 as described above into the box-shaped insulating sheet 30. Alternatively, the insulating sheet 30 in the unfolded state shown in FIG. 12 may be assembled in a box shape while being bent and curved along the surface of the electrode body 20.

  In any case, the box-shaped insulating sheet 30 covering the electrode body 20 is attached to the assembly body 2 by being joined to the upper spacer 90 at the third and fourth seal portions 32e and 33e. Thus, the electrode body 20 is accommodated in the case body 11 in a state where the insulating sheet 30 is assembled to the assembly body 2 so as to cover the electrode body 20, so that the space between the electrode body 20 and the inner surface of the case body 11 is reduced. The insulating sheet 30 is disposed on the surface.

  As shown in FIGS. 10 and 11, in the box-shaped insulating sheet 30, each protrusion 34 of the bottom surface portion 31 is spaced from the adjacent long side surface portions 32, 33 and short side surface portions 38 a, 38 b. Accordingly, communication portions 39a and 39b are formed at the corner portions at both ends in the longitudinal direction of the bottom surface portion 31 so as to communicate the internal space and the external space of the insulating sheet 30. Thereby, the gas generated between the layers of the electrode body 20 covered with the insulating sheet 30 can be discharged to the outside of the insulating sheet 30 from the communication portions 39a and 39b.

  In the example shown in FIGS. 10 and 11, the first seal portion 32c is overlapped on the outside of the second seal portion 33c, but the second seal portion 33c may be overlapped on the outside of the first seal portion 32c. Good.

  The arrangement of the electrode body 20 and the insulating sheet 30 in the case body 11 will be described with reference to FIGS.

  As shown in the cross-sectional view of FIG. 13, each linear portion 20 c of the electrode body 20 is disposed to face the long side wall portion 11 c of the case body 11 via the long side surface portions 32 and 33 of the insulating sheet 30. Each curved portion 20 d of the electrode body 20 is disposed to face the short side wall portion 11 d of the case body 11 through the short side surface portions 38 a and 38 b of the insulating sheet 30. Note that one end surface portion 20b of the electrode body 20 is disposed opposite to the bottom wall portion 11b of the case body 11 via the bottom surface portion 31 and the bottom spacer 40 of the insulating sheet 30 (FIGS. 1, 2, and 10). reference).

  In order to increase the capacity of the battery 1, it is required to maximize the dimensions of the electrode body 20 to the extent that the battery 1 can be accommodated in the exterior body 10 having a predetermined dimension. Therefore, it is preferable to arrange the outer peripheral surface of the electrode body 20 as close as possible to the inner surface of the case body 11. In this regard, each linear portion 20c of the electrode body 20 can be arranged with almost no gap between the long side surface portions 32 and 33 of the insulating sheet 30 with respect to the long side wall portion 11c of the case body 11. On the other hand, each curved portion 20d of the electrode body 20 is arranged as close as possible to the short side wall portion 11d of the case body 11 with the following configuration.

  With reference to FIGS. 14 and 15, the arrangement of one curved portion 20 d of the electrode body 20 and its peripheral portion will be described. In addition, although illustration and description are omitted, the other curved portion 20d of the electrode body 20 and its peripheral portion are similarly arranged.

  As shown in FIGS. 14 and 15, the outer peripheral surface of the curved portion 20d of the electrode body 20 is semicircular when viewed from the direction in which the winding axis A (see FIG. 3) extends, and the case body 11 is viewed from the same direction. It is almost rectangular. Therefore, a space is formed between the curved portion 20d of the electrode body 20 and both side corner portions 11e of the short side wall portion 11d of the case body 11 facing the curved portion 20d. The curved portion 20d is closest to the short side wall portion 11d at the top portion 20e. The top part 20e means the center part of the circumferential direction in the outer peripheral surface of the curved part 20d. When viewed from the direction in which the winding axis A (see FIG. 3) extends, the apex 20e is disposed at the end of the electrode body 20 in the longitudinal direction.

  Between the curved portion 20 d and the short side wall portion 11 d of the case body 11, the short side surface portion 38 a of the insulating sheet 30 is disposed. As described above, in the short side surface portion 38a, the first protrusion portion 32a protruding from the first long side surface portion 32 and the second protrusion portion 33a protruding from the second long side surface portion 33 are overlapped and joined. It is formed with.

  The first projecting portion 32a of the insulating sheet 30 forms a corner portion 32f in the space between the curved portion 20d and the corner portion 11e of the case main body 11, and a portion on the tip side of the corner portion 32f is short of the case main body 11. It arrange | positions along the inner surface of the side wall part 11d.

  The second projecting portion 33a of the insulating sheet 30 forms a corner portion 33f in the space between the curved portion 20d and the corner portion 11e of the case main body 11, and the tip side of the corner portion 33f is a short portion of the case main body 11. It arrange | positions along the inner surface of the side wall part 11d.

  Each corner part 32f, 33f of the insulating sheet 30 has a curved shape, for example, in an arc shape. The curvature radii of the corner portions 32f and 33f are larger than the curvature radius of the corner portion 11e of the case body 11 and smaller than the curvature radius of the curved portion 20d.

  Regarding the circumferential direction of the curved portion 20d, the circumferential length L of the portion facing the curved portion 20d in the insulating sheet 30 is larger than the circumferential length L1 of the curved portion 20d, and the portion of the inner surface of the case body 11 facing the curved portion 20d. It is smaller than the circumference L2. A space S1 is formed between the corner portions 32f and 33f of the insulating sheet 30 and the corner portion 11e of the case body 11, and a space S2 is formed between the corner portions 32f and 33f of the insulating sheet 30 and the curved portion 20d. Has been. These spaces S1 and S2 can serve as a passage for gas flowing from the bottom side of the case body 11 toward the opening side.

  With respect to the radial direction of the curved portion 20d, the corner portions 32f and 33f are disposed so as to pass through positions where the distance from the corner portion 11e of the case body 11 is smaller than the distance from the curved portion 20d. Thereby, the space S1 is formed smaller than the space S2.

  The size of the cross-sectional area of the spaces S1 and S2 viewed from the direction in which the winding axis A (see FIG. 3) extends can be adjusted by increasing or decreasing the circumferential length L of the insulating sheet 30. By increasing the cross-sectional area of the space S <b> 1, when the assembly body 2 assembled with the insulating sheet 30 is inserted into the case main body 11, the insulating sheet 30 is less likely to interfere with the case main body 11, and thus into the case main body 11. It becomes easy to insert the assembly body 2.

  When the electrode body 20 is inserted into the insulating sheet 30 after forming the insulating sheet 30 by increasing the cross-sectional area of the space S2, the electrode body 20 is less likely to interfere with the insulating sheet 30, and the electrode is placed in the insulating sheet 30. It becomes easy to insert the body 20. On the other hand, when the insulating sheet 30 in the unfolded state shown in FIG. 12 is formed while being bent and curved along the surface of the electrode body 20, the joining work in the overlap portion 36 is performed by increasing the cross-sectional area of the space S2. It becomes easy to do.

  In the overlap part 36 of the first protrusion 32a and the second protrusion 33a, the seal part 32c at the tip of the first protrusion 32a and the seal part 33c at the tip of the second protrusion 33a are overlapped. Thus, the overlap part 36 is a thick part having the largest thickness in the insulating sheet 30. The thickness of the overlap part 36 is, for example, twice that of the other part of the insulating sheet 30.

  With respect to the circumferential direction of the curved portion 20d, the lengths of the first projecting portion 32a and the second projecting portion 33a are different, so that the overlap portion 36 is separated from the top portion 20e that is the closest portion of the curved portion 20d to the short side wall portion 11d. They are offset. Thereby, the overlap part 36 does not intervene between the top part 20e of the curved part 20d, and the short side wall part 11d, and the 2nd protrusion part 33a of the insulating sheet 30 interposes only one layer.

  Therefore, the curved portion 20d can be disposed closer to the short side wall portion 11d so that the distance between the curved portion 20d and the short side wall portion 11d is smaller than the thickness of the overlap portion 36. Theoretically, the distance between the curved portion 20d and the short side wall portion 11d can be made substantially the same as the thickness of one layer of the insulating sheet 30. With respect to the longitudinal direction of the electrode body 20 as viewed from the direction in which the winding axis A (see FIG. 3) extends, the curved portion 20d, the short side surface portion 38b, and the short side wall portion are provided on the opposite side of the portion shown in FIGS. By arranging 11d in the same manner, the curved portion 20d can be arranged as close as possible to the short side wall portion 11d.

  Moreover, in this embodiment, the overlap part 36 is opposingly arranged by the part different from the top part 20e in the curved part 20d. Thereby, the overlap part 36 can be arrange | positioned using the space between the curved part 20d and the corner part 11e of the case main body 11. FIG. Therefore, it is avoided that the overlap part 36 intervenes between the straight part 20c of the electrode body 20 and the long side wall part 11c of the case body 11, thereby insulating the straight part 20c from the long side wall part 11c. The long side surfaces 32 and 33 of the sheet 30 can be arranged as close as possible with only one layer interposed.

  Therefore, according to this embodiment, the space | interval of the inner surface of the case main body 11 and the electrode body 20 becomes the minimum, preventing the short circuit between the case main body 11 and the electrode body 20 with the insulating sheet 30 effectively. Thus, the capacity of the battery 1 can be increased by increasing the size of the electrode body 20 as much as possible.

  In particular, since both the overlapping portions 36 of the insulating sheet 30 are arranged so as to be shifted in the circumferential direction from the top portion 20e of the bending portion 20d of the electrode body 20 facing each other, both the bending portions 20d and the case main body 11 are arranged. The distance from the short side wall portion 11d can be minimized. Thereby, the capacity | capacitance of the battery 1 can be effectively increased because the dimension of the electrode body 20 is increased effectively.

  Further, according to the present embodiment, since the overlap portion 36 is provided for each curved portion 20d, the electrode body 20 can be easily covered by using, for example, the unfolded insulating sheet 30 as shown in FIG. can do. Specifically, as described above, by folding the insulating sheet 30 in the expanded state, the electrode body 20 is sandwiched between the pair of long side surface portions 32 and 33, and the first protrusion portion 32a and the second protrusion portion 33a are sandwiched. The electrode body 20 can be easily covered with the insulating sheet 30 only by joining the overlap portion 36. Thereby, the productivity of the battery 1 is improved.

  Furthermore, when covering the electrode body 20 by such a method, the space | interval of the electrode body 20 and the insulating sheet 30 is made small compared with the case where the electrode body 20 is inserted in the insulating sheet 30 previously formed in the box shape. It becomes easy to do. Thereby, an increase in the size of the electrode body 20 and, consequently, an increase in the capacity of the battery 1 can be realized more effectively.

  By the way, if the overlap part 36 is disposed opposite to the top part 20e of the curved part 20d, the electrode body 20 covered with the insulating sheet 30 is formed by the large thickness of the part covering the top part 20e in the insulating sheet 30. When the one end surface portion 20b of the electrode body 20 is inserted into the case body 11 in a posture facing the bottom wall portion 11b of the case body 11, the overlap portion 36 is easily caught on the short side wall portion 11d of the case body 11.

  On the other hand, according to this embodiment, since the overlap part 36 is displaced in the circumferential direction from the top part 20e of the curved part 20d, the thickness of the covering part of the top part 20e in the insulating sheet 30 is reduced. The Therefore, when the electrode body 20 covered with the insulating sheet 30 is inserted into the case main body 11 in the same posture as described above, the insulating sheet 30 is not easily caught by the case main body 11, and this insertion operation can be easily performed.

  Further, as shown in FIG. 14, the outermost layer and the second layer from the outside of the electrode body 20 are composed of two separators 23 and 23. The longitudinal end 23a of each separator 23 is fixed to the outer peripheral surface of the layer adjacent to the inside by an arbitrary fixing means such as an adhesive or an adhesive tape. In the circumferential position where the tip 23a of the separator 23 is located, the radial dimension of the electrode body 20 is larger than that of a portion adjacent to the circumferential direction by one layer.

  According to the present embodiment, the distal end 23a of the separator 23 is curved in the circumferential direction with respect to the top portion 20e that is the closest portion of the curved portion 20d with respect to the short side wall portion 11d of the case main body 11 and the long side wall portion 11c of the case main body 11. The end of the separator 23 is disposed between the end portion 20f which is the closest portion of the portion 20d and thereby faces the space S2 between the corner portion 32f of the insulating sheet 30 and the curved portion 20d. 23a can be arranged. The arrangement of the tip 23a of the separator 23 using the space S2 can increase the radial dimension of the circumferential portion of the electrode body 20 facing the space S2, thereby increasing the capacity of the battery 1. Can promote.

  In the example shown in FIG. 14, the tips 23a and 23a of the two separators 23 and 23 are both disposed between one end 20f and the top 20e of the curved portion 20d. The tip 23a of the separator 23 is disposed between one end 20f and the top 20e of the curved portion 20d, and the end 23a of the other separator 23 is disposed between the other end 20g and the top 20e of the curved portion 20d. You may arrange. Further, the tip 23a of one separator 23 is disposed between one end 20f, 20g and the top 20e of the curved portion 20d shown in FIG. 14, and the end 23a of the other separator 23 is shown in FIG. You may arrange | position between either one edge part and the top part of the curved part 20d on the opposite side to the curved part 20d.

  By the way, when performing shrink wrapping in which the insulating sheet 30 is molded while being thermally contracted in a state where the electrode body 20 is covered with the insulating sheet 30 that is sufficiently larger than the electrode body 20, an overlap portion as in the present embodiment occurs. Although there is no thermal influence on the electrode body 20 during heating for contracting the insulating sheet 30. On the other hand, in the present embodiment, even when the overlap portion 36 is heated when the first seal portion 32c and the second seal portion 33c are joined with the electrode body 20 covered with the insulating sheet 30, the electrode The thermal effect on the body 20 is limited in the vicinity of the overlap portion 36. Moreover, when joining the 1st seal part 32c and the 2nd seal part 33c by adhesion | attachment, a heating is not required for joining. Therefore, according to this embodiment, the performance degradation of the electrode body 20 due to heat can be suppressed.

  In the present embodiment, the shape of the insulating sheet 30 is not limited to the above shape, and the overlap portion 36 is disposed between the portion of the curved portion 20d that is displaced in the circumferential direction from the top portion 20e and the inner surface of the case body 11. Various modifications are possible as long as the shape is changed.

  In the modification shown in FIG. 16, the first protrusion 32 a and the second protrusion 33 a of the insulating sheet 30 are formed shorter than the configuration shown in FIGS. 14 and 15, and the curvature of the corners 32 f and 33 f is reduced. The radius is large. Thus, the corner portions 32f and 33f are arranged so as to pass through the vicinity of the intermediate portion between the bending portion 20d and the corner portion 11e of the case body 11 with respect to the radial direction of the bending portion 20d. Thereby, space S1 is expanded compared with the said structure, and it becomes easy to insert the assembly body 2 to which the insulating sheet 30 was attached in the case main body 11. FIG.

  Moreover, in the example shown in FIG. 16, the overlap part 36 is arrange | positioned at the corner part 32f. Thereby, since the insulating sheet 30 is stored in the case main body 11 so that the overlap portion 36 and the case main body 11 do not contact with each other, the first seal portion 32c and the first seal portion 32c are caused by friction between the overlap portion 36 and the case main body 11. It can prevent that the 2nd seal | sticker part 33c peels.

[Second Embodiment]
FIG. 17 shows the assembly 2 and the insulating sheet 130 included in the battery according to the second embodiment of the present invention. The battery structure of this embodiment is the same as that of the first embodiment except for the structure of the insulating sheet.

  As shown in FIG. 17, the insulating sheet 130 is formed by bending a strip-shaped sheet into an elliptical cylinder shape in accordance with the outer shape of the electrode body 20, and first and second seal portions 132 a provided at both ends in the longitudinal direction. It is formed by superimposing and joining 133a to each other.

  The insulating sheet 130 thus formed includes a pair of long side surface portions 132 and 133 that face the straight portion 20c of the electrode body 20, and a first short side surface portion 134 that faces one of the curved portions 20d of the electrode body 20. And a second short side surface portion 138 facing the other curved portion 20d of the electrode body 20.

  The first short side surface portion 134 is configured by a portion obtained by curving the central portion in the longitudinal direction of the strip-shaped insulating sheet 130. The second short side surface portion 138 is constituted by both longitudinal ends of the insulating sheet 130 including the first and second seal portions 132a and 133a.

  As shown in FIG. 18, also in the second embodiment, the overlap portion 136 is formed by the first seal portion 132c and the second seal portion 133c being overlapped with each other. The overlap portion 136 is formed at a position where the distance from the first long side surface portion 132 is smaller than the distance from the second long side surface portion 133.

  In the overlap part 136, the first and second seal parts 132c and 133c are joined to each other. The first and second seal portions 132c and 133c may be joined by an arbitrary method, for example, by bonding using an adhesive or welding.

  A pair of corner portions 132 f and 133 f are formed on the second short side surface portion 138 of the insulating sheet 130. A space S11 is formed between the corner portions 132f and 133f and the corner portion 11e of the case body 11 facing the corner portions 132f and 133f, and a space S12 is formed between the corner portions 132f and 133f of the insulating sheet 130 and the curved portion 20d. Is formed. These spaces S <b> 11 and S <b> 12 can serve as a passage for gas flowing from the bottom side of the case body 11 toward the opening side.

  With respect to the circumferential direction of the bending portion 20d, the overlap portion 136 is arranged so as to be shifted from the top portion 20e of the bending portion 20d. Thereby, the overlap part 136 is not interposed between the top part 20e of the curved part 20d and the short side wall part 11d of the case body 11, and only one layer of the insulating sheet 130 is interposed. Therefore, similarly to the first embodiment, the curved portion 20d can be arranged as close as possible to the short side wall portion 11d.

  In addition, the overlap portion 136 is disposed using the space between the curved portion 20d and the corner portion 11e of the case main body 11, whereby the straight portion 20c of the electrode body 20 and the long side wall portion 11c of the case main body 11 are arranged. As a result, it is possible to prevent the overlap portion 136 from being interposed between the long side wall portion 11c and the long side wall portion 11c with only one layer of the long side surfaces 132 and 133 of the insulating sheet 130. Can be placed close to.

  Therefore, also in 2nd Embodiment, the space | interval of the inner surface of the case main body 11 and the electrode body 20 becomes the minimum, preventing the short circuit between the case main body 11 and the electrode body 20 by the insulating sheet 130 effectively. Thus, the capacity of the battery 1 can be increased by increasing the size of the electrode body 20 as much as possible.

  Moreover, also in 2nd Embodiment, the overlap part 136 is shifted | deviated to the circumferential direction from the top part 20e of the curved part 20d, and the thickness of the coating | coated part of the top part 20e in the insulating sheet 130 is reduced. Therefore, when the electrode body 20 covered with the insulating sheet 130 is inserted into the case main body 11 in the same posture as in the first embodiment, the insulating sheet 130 is not easily caught by the case main body 11, and the above insertion operation is easily performed. be able to.

  Further, also in the second embodiment, the tip 23a of the separator 23 is disposed between the end 20f and the top 20e of the curved portion 20d in the circumferential direction, and thereby, the corner portion 132f of the insulating sheet 130 and The front end 23a of the separator 23 can be disposed so as to face the space S12 between the curved portion 20d. By arranging the tip 23a of the separator 23 using such a space S12, the radial dimension of the circumferential portion of the electrode body 20 facing the space S12 can be increased, thereby increasing the capacity of the battery 1. Can promote.

  While the present invention has been described with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments.

  For example, in the above-described embodiment, the case where the thick portion of the insulating sheet is composed of an overlap portion where two sheet portions overlap is described. However, when the thickness of the insulating sheet is not constant, the thick portion is not in the insulating sheet. If it is a part which has the largest thickness, it may consist of one sheet part. In this case as well, the capacity of the battery 1 can be increased similarly by arranging the thick portion as in the above-described embodiment.

  Furthermore, in the above-described embodiment, a case has been described in which one overlap portion 36, 136 of the insulating sheets 30, 130 is opposed to one curved portion 20d of the electrode body 20, but with respect to one curved portion. A plurality of overlap portions may be arranged to face each other. In this case, the same effect as described above can be obtained by disposing any overlap portion in the circumferential direction from the closest portion of the curved portion to the inner surface of the exterior body.

  Moreover, although the above-mentioned embodiment demonstrated the case where the curved part 20d of the electrode body 20 opposes the short side wall part 11d of the case main body 11, this invention opposes any part of the inner surface of an exterior body. It can also be applied to cases.

  Furthermore, in the above-described embodiment, the power storage device according to the present invention has been described by taking a lithium ion secondary battery as an example. However, the present invention is not limited to a secondary battery other than a lithium ion secondary battery, a primary battery, and various capacitors. Applicable to power storage elements.

1 Battery (storage element)
2 Assembly body 10 Exterior body 11 Case body 11a Opening 11b Bottom wall portion 11c Long side wall portion 11d Short side wall portion (opposing surface portion)
11e Corner portion 12 Lid 12a Outer side surface 12b Inner side surface 20 Electrode body 20a, 20b End surface portion 20c Linear portion 20d Curved portion 21 Positive electrode sheet 22 Negative electrode sheet 23 Separator 24 Positive electrode metal foil 24a Uncoated portion 24b Protrusion portion 25 Positive electrode activity Material layer 26 Negative electrode metal foil 26a Uncoated portion 26b Protrusion portion 27 Negative electrode active material layer 28 Positive electrode current collecting tab 29 Negative electrode current collecting tab 30 Insulating sheet 31 Bottom surface portion 32 First long side surface portion 32a First protrusion portion 32c First seal Part 32f Corner part 33 Second long side part 33a Second protrusion 33c Second seal part 33f Corner part 36 Overlap part (thick part)
38a, 38b Short side portion 39a, 39b Communication portion 40 Bottom spacer 50A, 50B External terminal 51A, 51B Plate-like portion 52 Shaft portion 52a Expanded portion 53 Rivet 53a Jaw portion 53b Expanded portion 60A, 60B Current collector 61A, 61B Welded parts 62A, 62B Clamped parts 70A, 70B Upper packing 80A, 80B Lower packing 90 Upper spacer 130 Insulating sheet 132 First long side part 132a First seal part 132f Corner part 133 Second long side part 133a Second Seal part 133f Corner part 134 1st short side part 136 Overlap part (thick part)
138 Second short side surface

Claims (6)

An electrode body having a curved portion;
An exterior body having an opposing surface portion facing the curved portion and containing the electrode body;
An insulating sheet disposed between the electrode body and the inner surface of the exterior body, having a thick part where two sheet parts overlap;
The electrical storage element, wherein the thick portion is disposed to face the bending portion at a position shifted in a circumferential direction of the bending portion from a closest portion of the bending portion with respect to the facing surface portion. An electrode body having a curved portion;
An exterior body having an opposing surface portion facing the curved portion and containing the electrode body;
An insulating sheet disposed between the electrode body and the inner surface of the exterior body,
The thick part having the largest thickness in the insulating sheet is disposed opposite to the bending part at a position shifted in the circumferential direction of the bending part from the closest part of the bending part to the opposing surface part. A power storage element. The exterior body includes a case main body having a bottom portion and an opening facing the bottom portion, and a lid for closing the opening,
The said electrode body is arrange | positioned in the attitude | position in which the said curved part opposes the surface different from the surface in which the said bottom part and the said opening in the said case main body were provided. Power storage element. The electrode body includes a pair of the curved portions,
The opposed surface part and the thick part are provided for each of the curved parts,
2. Any of the thick portions is disposed to face the bending portion at a position shifted from the closest approach portion of the bending portion to the facing surface portion in the circumferential direction of the bending portion. The electrical storage element of any one of Claim 3.   The electrode body includes a positive electrode sheet and a negative electrode sheet each having a metal foil and an active material layer formed on the metal foil, and a separator between the positive electrode sheet and the negative electrode sheet. 5. The power storage element according to claim 1, wherein the power storage element is wound so as to be interposed therebetween. The exterior body includes another surface portion adjacent to the facing surface portion via a corner,
The outermost layer of the electrode body is composed of the separator,
In the circumferential direction of the electrode body, a tip of the separator is disposed between the closest portion of the curved portion with respect to the facing surface portion and a closest portion of the electrode body with respect to the other surface portion. The electric storage element according to claim 5.

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