JP6787650B2 - Power storage element and its manufacturing method - Google Patents

Description

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

The secondary battery disclosed in Patent Document 1 includes a case main body, a lid for closing the opening of the case main body, and an electrode body housed in the case main body. The electrode body is formed by winding positive and negative electrode sheets so as to be alternately laminated via a separator. The electrode body is housed in the case body in a posture in which the winding axis (winding shaft) extends in the vertical direction. An upper spacer for insulation is arranged between the electrode body and the lid.

JP-A-2006-120634

In the secondary battery disclosed in Patent Document 1, the end portion of the tubular electrode body is pressed via the upper spacer when the electrode body is housed in the case body. Specifically, since the separator protrudes from the end of the electrode body, the protruding portion of the separator is pressed by the upper spacer. Patent Document 1 does not give any special consideration to prevent an excessive load from acting on the separator protruding from the end of the electrode body.

An object of the present invention is to prevent an excessive load from acting on the separator when the electrode body of the power storage element is housed in the exterior body.

A first aspect of the present invention is an electrode body having a pair of straight portions whose ends face each other and a pair of curved portions facing each other so as to connect these straight portions, and a bottom portion and the bottom portion thereof. An exterior body including a case body having an opening facing the case body and a lid for closing the opening of the case body, and the electrode body is housed in the case body with the end portion facing the lid portion. An upper portion arranged between the lid and the end portion of the electrode body and having a first portion covering the pair of straight portions of the electrode body and a second portion covering the curved portion of the electrode body. A power storage element provided with a spacer, wherein the amount of protrusion of the lid of the first part from the most case body side of the lid is smaller than the amount of protrusion of the lid of the second part from the most case body side. I will provide a.

Specifically, the electrode body includes a positive electrode sheet and a negative electrode sheet having a metal foil and an active material layer formed on the metal foil, and a separator, and the positive electrode sheet and the negative electrode sheet. Is wound around the winding axis so as to interpose the separator, and the edge portion of the separator is bent toward the winding axis.

Since the bent portion is provided at the edge portion of the separator, the curved portion of the electrode body protrudes toward the lid side from the straight portion. The amount of protrusion from the lid is smaller in the second portion (curved portion of the electrode body) than in the first portion (opposing the straight portion of the electrode body) of the upper spacer. Therefore, when the electrode body housed in the case body is pressed toward the bottom of the case body by the upper spacer, the first portion of the upper spacer presses the straight portion of the electrode body and the second upper spacer. The pressing force at which the portion presses the curved portion of the electrode body can be made uniform, and an excessive load does not act on the edge portion of the separator at the curved portion of the electrode body.

A second aspect of the present invention is an electrode body having a pair of straight portions having ends facing each other and a pair of curved portions facing each other so as to connect these straight portions, and a bottom portion and the bottom portion thereof. An exterior body including a case body having an opening facing the case body and a lid for closing the opening of the case body, and the electrode body is housed in the case body with the end portion facing the lid portion. Provided is a power storage element which is arranged between the lid and the end portion of the electrode body and includes an upper spacer which covers only the straight portion of the electrode body.

A third aspect of the present invention provides a method for manufacturing a power storage element including the following. An electrode body having a pair of straight portions whose ends face each other and a pair of curved portions facing each other so as to connect these straight portions is prepared. The electrode body is assembled to the lid with an upper spacer interposed therebetween, and the upper spacer has a first portion of the electrode body facing the straight portion and a second portion of the electrode body facing the curved portion. The amount of protrusion of the lid of the first part from the most case body side portion of the lid is smaller than the amount of protrusion of the lid of the second part from the most case body side portion. The electrode body is inserted into the case body through the opening of the case body. By pushing the lid toward the opening of the case body, the first portion of the upper spacer is pressed against the straight portion of the end portion of the electrode body, and the second portion of the upper spacer is pressed. It presses against the curved portion of the end portion of the electrode body.

A fourth aspect of the present invention provides a method for manufacturing a power storage element including the following. An electrode body having a pair of straight portions whose ends face each other and a pair of curved portions facing each other so as to connect these straight portions is prepared. The electrode body is assembled to the lid with the upper spacer interposed therebetween, and the upper spacer includes only a portion of the electrode body facing the straight portion. By pushing the lid toward the opening of the case body, the upper spacer is pressed against the straight portion of the end portion of the electrode body.

According to the power storage element and the manufacturing method thereof according to the present invention, it is possible to prevent an excessive load from acting on the edge of the separator when the electrode body is housed in the case.

The vertical sectional view of the lithium ion secondary battery which concerns on 1st Embodiment of this invention. The exploded perspective view of the lithium ion secondary battery of FIG. Perspective view of the electrode body. Development view of the electrode body. An enlarged view of a portion V of FIG. An enlarged view of the partial VI of FIG. The perspective view of the electrode body and the current collector. FIG. 1 is a perspective view of a partially broken portion of the lithium ion secondary battery of FIG. Partial fracture decomposition side view of the lithium ion secondary battery of FIG. Side view of the electrode body. Partial plan view of the electrode body. Partial bottom view of the electrode body. FIG. 10 is a schematic partial cross-sectional view taken along the line XIII-XIII of FIG. FIG. 10 is a schematic partial cross-sectional view taken along the line XIV-XIV of FIG. Schematic partial cross-sectional view of an electrode body before providing a bent portion in a separator. A perspective view seen from above the upper spacer. A perspective view seen from below the upper spacer. Partial bottom view of the upper spacer. FIG. 18 is a schematic cross-sectional view taken along the line XIX-XIX. The perspective view seen from the lower side of the upper spacer which concerns on 2nd Embodiment. Partial bottom view of the upper spacer according to the second embodiment. FIG. 2 is a schematic cross-sectional view taken along the line XXII-XXII of FIG. FIG. 5 is a cross-sectional view similar to FIG. 5 of the lithium ion secondary battery according to the third embodiment of the present invention. FIG. 6 is a cross-sectional view similar to FIG. 6 of the lithium ion secondary battery according to the fourth embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described with reference to the accompanying drawings. In the following description, terms indicating a specific direction or position (for example, terms including "top", "bottom", "side", and "edge") are used as necessary, but the use of these terms is used. Is for facilitating the understanding of the invention with reference to the drawings, and the meaning of those terms does not limit the technical scope of the present invention. In addition, the following description is merely an example and is not intended to limit the present invention, its application, or its use.

1 and 2 show a lithium ion secondary battery (hereinafter, simply referred to as a battery) 1 according to an embodiment of the present invention.

(overall structure)
Referring to FIGS. 1 and 2, the battery 1 includes an exterior body 10, an electrode body 20, an insulating sheet 30, a bottom spacer 40, positive and negative electrode external terminals 50A and 50B, positive and negative current collectors 50A and 50B, and an upper packing. It includes 70A, 70B, lower packings 80A, 80B, and an upper spacer 90.

The exterior body 10 includes a case body 11 and a lid 12 that closes the opening 11a of the case body 11. In this embodiment, the case body 11 and the lid 12 are made of aluminum or an aluminum alloy. The case body 11 has a rectangular plate-shaped bottom wall portion (bottom 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. And. The lid 12 has a substantially rectangular plate shape. The upper ends of the long side wall portion 11c and the short side wall portion 11d define the opening 11a of the case body 11. The electrode body 20 is housed 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 11b of the case body 11. The lower packings 80A and 80B and the upper spacer 90 are also housed in the case body 11.

With reference to FIGS. 3 and 4, the electrode body 20 is formed by two separators 23 composed of a positive electrode sheet 21, a negative electrode sheet 22, and a microporous resin sheet, each of which has a long strip of constant width. , 23 are overlapped and wound into an oblong shape with a substantially 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 winding axis (winding shaft) of the positive electrode sheet 21, the negative electrode sheet 22, and the two separators 23, 23 is conceptually indicated by reference numeral A in FIG. The electrode body 20 is housed in the case body 11 in a posture in which the winding shaft A extends in a direction in which the bottom wall portion 11b of the case body 11 and the lid 12 face each other (vertical direction in FIG. 1).

As shown in FIG. 3, the ends 20a and 20b of the electrode body 20 viewed from the extending direction of the winding shaft A connect a pair of straight portions 20c and 20c facing each other and these straight portions 20c and 20c. As described above, it has a pair of curved portions 20d and 20d facing each other. The straight portion 20c is a portion that extends linearly in design. In a state where the electrode body 20 is actually housed in the exterior body 10, the straight line portion 20c is not always arranged in a completely straight line, but is bent so as to have a shape close to a straight line as a whole. It may be placed in.

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

The negative electrode electrode sheet 22 includes a strip-shaped negative electrode metal foil 26 and a negative electrode active material layer 27 formed on both sides of the negative electrode metal foil 26. At one end (lower side in FIGS. 3 and 4) of the negative electrode electrode sheet 22 in the width direction, 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 (upper side in FIGS. 3 and 4) of the negative electrode electrode sheet 22 in the width direction, an uncoated portion 26a in which the negative electrode metal foil 26 is exposed is provided without providing the negative electrode active material layer 27. ing. The width of the negative electrode sheet 20 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 20.

The positive electrode metal foil 24 is provided with a plurality of protrusions 24b protruding outward in the width direction from the uncoated portion 24a at intervals in the longitudinal direction. In a state where the positive electrode sheet 21, the negative electrode sheet 22, and the separators 23 and 23 are overlapped and wound, a tab-shaped portion (positive electrode current collecting tab) in which a plurality of protrusions 24b are overlapped with each other and protrudes from the electrode body 20. 28) 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, and these protrusions 26b are overlapped with each other to collect negative electrode current protruding from the electrode body 20. The tab 29 is formed.

Referring to FIG. 3, the positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 project from one end 20a (upper end in FIG. 3) of the electrode body 20. Further, one side of the pair of straight portions 20c and 20c (the 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 extending direction of the winding shaft A. The positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 project from the above.

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

Referring to FIG. 5 in addition to FIGS. 1 and 2, the positive electrode external terminal 50A has a plate-shaped portion 51A arranged on the outer surface 12a of the lid 12 and a cylindrical shape protruding downward from the lower surface of the plate-shaped portion 51A. The shaft portion 52 of the above is provided. The plate-shaped portion 51A and the shaft portion 52 are integrally molded. The shaft portion 52 penetrates the lid 12 and projects inside the case body 11.

An enlarged diameter portion 52a is provided at the lower end of the shaft portion 52 of the external terminal 50A of the positive electrode, whereby the external terminal 50A of the positive electrode is crimped and fixed to the lid 12. Specifically, between the plate-shaped portion 51A of the external terminal 50A and the enlarged diameter portion 52a, an insulating resin upper packing 70A, a lid 12, an insulating resin lower packing 80A, and a positive electrode current collector 60A. The external terminal 50A of the positive electrode and the current collector 60A are fixed to the lid 12 by sandwiching (the crimped portion 62A described later). The upper packing 70A is interposed between the outer surface 12a of the lid 12 and the outer terminal 50A, and the lower packing 80A is interposed between the inner side surface (lower side surface) 12b of the lid 12 and the current collector 60A. ing. In the present embodiment, the external terminal 50 of the positive electrode 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 electrode external terminal 50B includes a plate-shaped portion 51B arranged on the outer surface 12a of the lid 12 and a rivet 53 separate from the plate-shaped portion 51B. .. The jaw portion 53a at the upper end of the rivet 53 is press-fitted into the through hole formed in the plate-shaped portion 51B, whereby the rivet 53 is fixed to the plate-shaped portion 51B. The rivet 53 projects downward from the lower surface of the plate-shaped portion 51B, penetrates the lid 12, and projects inside the case body 11.

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

As most clearly shown in FIG. 7, the positive electrode current collector 60A includes a welded portion 61A and a clamped portion 62A. The portion 61A to be welded 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 on the shaft portion 52 of the external terminal 50A of the positive electrode. Similarly, the negative electrode current collector 60B includes a welded portion 61B and a crimped portion 62B. The portion 61B to be welded 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 external terminal 50B of the negative electrode.

As most clearly shown in FIGS. 8 and 9, an upper spacer 90 is interposed between the electrode body 20 and the inner side surface 12a of the lid 12.

(Details of electrode body)
As conceptually indicated by arrows in FIGS. 11 and 12, at any of the ends 20a and 20b of the electrode body 20, the edge of the separator 23 protruding from these ends 20a and 20b is formed on the winding shaft A. It is bent inward of the electrode body 20 (in other words, on the winding shaft A side) when viewed from the extending direction. Further referring to FIGS. 13 and 14, at the upper end 20a of the electrode body 20, the edge (upper end) of the separator 23 protrudes upward from the edge (upper end) of the positive electrode sheet 21 and the negative electrode sheet 22. (See also reference numeral C1 in FIG. 4), and the separator 23 in this portion is bent inside the electrode body 20 to form the bent portion 23a. Similarly, at the lower end 20b of the electrode body 20, the edge (lower end) of the separator 23 protrudes downward from the edge (lower end) of the positive electrode sheet 21 and the negative electrode sheet 22 (FIG. 4). (See also with reference numeral C2), the separator 23 in this portion is bent inside the electrode body 20 to form the bent portion 23a.

As described above, at the upper end portion 20a of the electrode body 20, the positive electrode current collector tab 28 and the negative electrode current collector 29 project from one straight line portion 20c. At the end portion 20a of the electrode body 20, a bent portion 23a is provided on the separator 23 at a portion other than the portion where the positive electrode current collector tab 28 and the negative electrode current collector 29 are arranged. On the other hand, at the lower end portion 20b of the electrode body 20, the bent portions 23a of the separator 23 are provided in all of the pair of straight portions 20c and 20c and the pair of curved portions 20d and 20d.

As is clear from comparison between FIGS. 13 and 14 (a state in which the bent portion 23a is formed on the separator 23) and FIG. 15 (a state in which the bent portion 23a is not formed on the separator 23), the bent portion 23a is formed. By forming the electrode sheet 21, the edges of the positive electrode sheet 21 and the negative electrode sheet 22 in the width direction are covered with the separator 23. By covering the edges of the positive electrode sheet 21 and the negative electrode sheet 22 with the bent portion 23a in this way, the positive electrode sheet 21 and the negative electrode sheet 22 can be reliably insulated.

After forming the bent portion 23a, the amount of protrusion of the edge portion of the separator 23 from the upper end portion 20a of the electrode body 20 (conceptually indicated by reference numerals D1 and D2 in FIGS. 13 and 14) is determined by the bent portion 23a. It is smaller than the amount of protrusion of the edge portion of the separator 23 from the end portion 20a of the electrode body 20 (conceptually indicated by reference numeral D3 in FIG. 15) before the formation of the electrode body 20. Similarly, the amount of protrusion of the edge portion of the separator 23 from the lower end portion 20b of the electrode body 20 after forming the bent portion 23a is also smaller than the amount of protrusion before forming the bent portion 23a. Therefore, by forming the bent portion 23a, the electrode body 20 can be miniaturized, thereby increasing the capacity of the battery 1.

As described above, by providing the bent portions 23a of the separator 23 at the end portions 20a and 20b of the electrode body 20, the positive electrode body 20 and the negative electrode body 22 are surely insulated, and the electrode body 20 is relatively large. The capacity of the battery 1 can be increased.

As is clear from reference numerals C1 and C2 in FIG. 4, the amount of protrusion of the edge of the separator 23 from the edge (upper edge in the figure) of the negative electrode electrode sheet 22 at the end 20a is the negative electrode at the end 20b. It is larger than the amount of protrusion of the edge of the separator 23 from the edge of the electrode sheet 22 (lower edge in the figure). Therefore, as shown in FIG. 10, the protrusion amount (reference numerals δ1, δ2) of the bent portion 23a of the separator 23 at the upper end portion 20a of the electrode body 20 is the bending portion 23a of the separator 23 at the lower end portion 20b. It is larger than the amount of protrusion (reference numerals δ3, δ4).

By providing the bent portion 23a of the separator 23 only on one of the end portions 20a and 20b of the electrode body 20, the positive electrode sheet 21 and the negative electrode sheet 22 are surely insulated and the capacity of the battery 1 is increased. be able to.

As is clear from FIG. 2, by providing the bent portion 23a of the separator 23 at the lower end portion 20b of the electrode body 20, when the electrode body 20 is housed in the case body 11, the end portion 20b is provided. It smoothly moves along the inner surfaces of the long side wall portion 11c and the short side wall portion 11d of the case body 11. In other words, by providing the bent portion 23a of the separator 23 at the lower end portion 20b of the electrode body 20, the workability when the electrode body 20 is housed in the case body 11 is improved.

Referring to FIG. 15 together, before forming the bent portion 23a, the amount of protrusion of the edge portion of the separator 23 from the end portion 20a of the electrode body 20 (conceptually indicated by reference numeral D3) is the linear portion 20c. It is the same as the curved portion 20d. However, as can be understood from the arrow in FIG. 11, when the edge portion of the separator 23 is bent inside the electrode body 20, the plurality of separators 23 are viewed from the extending direction of the winding shaft A in the portion of the straight portion 20c. It can be bent while maintaining its original posture or shape. On the other hand, in the curved portion 20d, when the separator 23 is bent toward the inside of the electrode body 20, the arcuate shape when viewed from the extending direction of the winding shaft A is reduced. Therefore, as shown in FIGS. 13 and 14, the bending amount of the bent portion 23a of the separator 23 in the straight portion 20c is smaller than the bending amount of the bent portion 23a of the separator 23 in the curved portion 20d. Further, due to this difference in the bending amount, after the bending portion 23a is formed, the protrusion amount of the edge portion of the separator 23 from the end portion 20a of the electrode body 20 in the bending portion 20d (reference numeral D2 is conceptually shown in FIG. 14). ) Is larger than the amount of protrusion of the edge portion of the separator 23 from the end portion 20a of the electrode body 20 in the straight portion 20c (conceptually indicated by reference numeral D1 in FIG. 13). Similarly, also at the lower end portion 20b of the electrode body 20, since the bent portion 23a is formed at the edge portion of the separator 23, the amount of protrusion of the edge portion of the separator 23 at the curved portion 20d is the straight portion 20c. It is larger than the amount of protrusion of the edge of the separator 23.

For the above reasons, as conceptually shown by reference numerals δ1 and δ2 in FIG. 10, the upper end 20a (upper end in the figure) facing the lid 12 (see FIG. 1) of the electrode body 20 is a straight line. The curved portion 20d protrudes from the portion 20c toward the lid 12 side (upper side in the drawing). Further, as conceptually shown by reference numerals δ3 and δ4 in FIG. 10, the lower end portion 20b (lower end portion in the drawing) with respect to the bottom wall portion 11b of the case body 11 of the electrode body 20 is a straight portion. The curved portion 20d protrudes from the 20c toward the bottom wall portion 11b side (lower side in the figure).

(Upper spacer)
Referring to FIGS. 16 and 17, the upper spacer 90 has a rectangular shape similar to that of the lid 12 as a whole, and includes a central portion 91 and a pair of current collector accommodating portions 92A and 92B extending from the central portion 91. One end of the current collector accommodating portions 92A and 92B is connected to the central portion 91, and the other end is connected to the clamped portion arranging portions 93A and 93B. The central portion 91 is provided with an opening 91a facing the safety valve provided on the lid 12. With reference to FIGS. 5 and 6, the current collector accommodating portions 92A and 92B include a side wall portion 92a, an upper wall portion 92b extending from the upper end of the side wall portion 92a, and an upper wall portion 92b from the lower end of the side wall portion 92a. It is provided with a lower wall portion 92c extending substantially in parallel. A gap 92e is formed between the ends of the upper wall portion 92b and the lower wall portion 92c on the side opposite to the side wall portion 92a. The clamped portion arranging portions 93A and 93B include a bottom wall portion 93a and an inner peripheral wall portion 93b formed on the bottom wall portion 93a. Further, on the bottom wall portion 93a, an outer peripheral wall portion 93c is provided so as to surround the inner peripheral wall portion 93b.

The upper spacer 90 insulates the current collectors 60A and 60B from the lid 12 and the electrode body 20. Further, the upper spacer 90 insulates the parts to be tightened 62A and 62B from the electrode body 20. Specifically, the positive and negative current collectors 60A, which are crimped and fixed to the lid 12. The positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 of the electrode body 20 are welded to the welded portions 61A and 61B (see, for example, FIG. 8) of the 60B, respectively. After that, as shown in FIG. 9, with the positive electrode current collecting tab 28 and the negative electrode current collecting tab 29 folded, the current collectors 60A and 60B are inserted through the gap 92e between the upper wall portion 92b and the lower wall portion 92c to perform the electrodes. Assemble the body 20 to the lid 12. The upper wall portion 92b insulates the current collectors 60A and 60B from the lid 12, and the lower wall portion 92c insulates the current collectors 60A and 60B from the electrode body 20. Further, in a state where the current collectors 60A and 60B are arranged between the upper wall portion 92b and the lower wall portion 92c, the crimped portions 62A and 62B are arranged on the crimped portion arranging portions 93A and 93B and the lid 12 Insulated against.

After assembling the electrode body 20 to the lid 12, the electrode body 20 is inserted into the case body 11 through the opening 11a, and the lid 12 is further pushed toward the bottom wall portion 11b of the case body 11, so that the electrodes are formed by the upper spacer 90. Press the upper end 20a of the body 20. After that, the lid 12 is welded to the case body 11.

Referring to FIGS. 17 to 19, the lower surfaces (first portion of the upper spacer) 92d of the central portion 91 and the lower wall portions 92c of the current collector accommodating portions 92A and 92B, and the clamped portion arranging portions 93A and 93B. The lower surface (second portion of the upper spacer) 93d of the bottom wall portion 93a is a flat surface, and is connected by an inclined surface 94. The flat surface is not limited to a flat surface in a geometrical sense, but is substantially flat with respect to the case where unavoidable irregularities due to manufacturing errors or the like are formed, or the height difference between the lower surfaces 92d and 93d. It also includes the case where unevenness that can be regarded as is formed. With reference to FIGS. 5 and 6, the lower surface 92d of the central portion 91 and the lower wall portions 92c of the current collector accommodating portions 92A and 92B is above the straight portion 20c of the upper end portion 20a of the electrode body 20. cover. Further, the lower surface 93d of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B covers the upper portion of the curved portion 20d of the upper end portion 20a of the electrode body 20.

As conceptually shown in FIG. 19, the lower surface 93d of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B, and the lower surface 92d of the lower wall portions 92c of the central portion 91 and the current collector accommodating portions 92A and 92B. There is a step between them. Specifically, from the lower surface 92d of the central portion 91 and the lower wall portions 92c of the current collector accommodating portions 92A and 92B to the lowermost end of the inner side surface 12b of the lid 12 (the bottom wall of the most case body 11 of the inner side surface 12b of the lid 12). From the lower surface 93d of the bottom wall portion 93a of the compacted portion arranging portions 93A and 93B to the lowermost end of the inner side surface 12b of the lid 12 (the most case body 11 of the inner side surface 12b of the lid 12) than the distance E1 to the portion 11b). The distance E2 to the bottom wall portion 11b side) is short. In other words, the lower surface 93d of the bottom wall 93a of the tightened portion arrangement 93A, 93B is on the upper side (lid 12 side) than the lower surface 92d of the central portion 91 and the lower wall 92c of the current collector accommodating portions 92A, 92B. positioned. In other words, the lowermost end of the inner side surface 12b of the lid 12 of the lower surface 92d of the central portion 91 and the lower wall portions 92c of the current collector accommodating portions 92A and 92B (the bottom wall of the most case body 11 of the inner side surface 12b of the lid 12). The lowermost end of the inner side surface 12b of the lid 12 (the most case of the inner side surface 12b of the lid 12) of the lower surface 93d of the bottom wall portion 93a of the parts to be tightened 93A and 93B, rather than the amount of protrusion E1 from the portion 11b side). The amount of protrusion E2 from the bottom wall portion 11b side of the main body 11 is small.

As described above, the amount of protrusion of the edge portion of the separator 23 from the end portion 20a of the electrode body 20 in the curved portion 20d (see reference numeral δ2 in FIG. 10 and reference numeral D2 in FIG. 14) is the amount of protrusion of the electrode body 20 in the linear portion 20c. It is larger than the amount of protrusion of the edge portion of the separator 23 from the end portion 20a (see reference numeral δ1 in FIG. 10 and reference numeral D1 in FIG. 13). Therefore, it is assumed that the entire lower surface of the upper spacer 90 is flat, that is, the lower surface 92d of the lower wall portions 92c of the current collector accommodating portions 92A and 92B and the lower surface 93d of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B have the same height. Then, by pushing the lid 12 toward the opening 11a of the case body 11, when the upper end 20a of the electrode body 20 is pressed by the upper spacer 90, the pressing force becomes non-uniform. Specifically, the curved portion 20d of the end portion 20a of the electrode body 20 is pressed excessively strongly, and the straight portion 20c is not substantially pressed. When such a state occurs, the separator 23 is damaged and the positive electrode sheet 21 and the negative electrode sheet 22 are damaged (for example, the metal of the active material layer) in the curved portion 20d of the electrode body 20 pressed excessively strongly by the upper spacer 90. (Peeling from the foil) etc. may occur.

However, in the present embodiment, in the upper spacer 90, the lower surface 93d of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B is above the lower surface 92d of the lower wall portions 92c of the current collector accommodating portions 92A and 92B ( Since it is located on the lid 12 side), the pressing force that the lower surface 92d of the lower wall portion 92c of the current collector accommodating portions 92A and 92B presses the straight portion 20c of the electrode body 20 and the clamped portion arranging portion 93A, The lower surface 93d of the bottom wall portion 93a of the 93B can make the pressing force pressing the curved portion of the electrode body uniform. That is, on the upper end portion 20a of the electrode body 20, the straight portion 20c and the curved portion 20d are uniformly pressed by the upper spacer 90, and an excessive load does not act on the curved portion 20d. As a result, when the upper end 20a of the electrode body 20 is pressed by the upper spacer 90, the separator 23 is damaged at the end 20a of the electrode body 20, the positive electrode sheet 21 and the negative electrode sheet 22 are damaged, and the like. Can be reliably prevented.

(Second Embodiment)
In the second embodiment, only the shape of the upper spacer 90 is different from the first embodiment. Referring to FIGS. 20 to 22, the upper spacer 90 in the present embodiment has a central portion 91 and the lower surface (first portion of the upper spacer) 92d of the lower wall portions 92c of the current collector accommodating portions 92A and 92B has a flat surface. Is. The lower surface 92d of the lower wall portions 92c of the current collector accommodating portions 92A and 92B and the lower surface of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B connected via the inclined surface 94 (second portion of the upper spacer). ) 93d includes a base portion (third portion of the upper spacer) 93e which is a flat surface, and a recess (fourth portion) 93f which is smoothly recessed from the base portion 93e toward the lid 12. The contour of the recess 93f seen from the direction in which the winding shaft A extends is generally horseshoe-shaped, and matches or conforms to the outer contour of the curved portion 20d of the electrode body 20 seen from the same direction.

As conceptually shown in FIG. 22, between the lower surface 93d of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B and the lower surface 92d of the lower wall portion 92c of the current collector accommodating portions 92A and 92B. , A step is formed. Specifically, the bottom of the clamped portion arranging portions 93A and 93B is larger than the protrusion amount E1 from the lowermost end of the inner side surface 12b of the lid 12 of the lower surface 92d of the lower wall portions 92c of the current collector accommodating portions 92A and 92B. Of the lower surface 93d of the wall portion 93a, the protrusion amount E2 from the lowermost end of the inner side surface 12 of the lid 12 of the base portion 93e is short. Further, the protrusion amount E3 from the lowermost end of the inner side surface 12b of the lid 12 of the recess 93f is shorter than the protrusion amount distance E2 from the lowermost end of the inner side surface 12b of the lid 12 of the base 93e.

The lower surface 93d of the bottom wall portion 93a of the clamped portion arranging portions 93A and 93B is provided with a recess 93f that is smoothly recessed from the base portion 93e toward the lid 12. Therefore, by pushing the lid 12 toward the bottom wall portion 11b of the case body 11, when the upper end portion 20a of the electrode body 20 is pressed by the upper spacer 90, it protrudes from the upper end portion 20a of the electrode body 20. The edge of the separator 23 is bent along the recess 93f. By bending along the recess 93f, a bent portion 23a is formed at the edge portion of the separator 23. In other words, the recess 93f functions as a guide for forming a bent portion at the edge portion of the separator 23 when the lid 12 is pushed toward the bottom wall portion 11b of the case body 11.

(Third Embodiment)
Also in the third embodiment, only the shape of the upper spacer 90 is different from that of the first embodiment. Referring to FIGS. 23 and 24, the upper spacer 90 in the present embodiment includes a central portion 91 (see FIG. 1) and a pair of current collector accommodating portions 92A and 92B having one end connected to the central portion 91. .. The other ends of the individual current collector accommodating portions 92A and 92B are terminated on the central portion 91 side of the enlarged diameter portions 52a and 53b of the external electrodes 50A and 50B. That is, at the other end of each current collector accommodating portion 92A, 92B, a portion corresponding to the clamped portion arranging portion 93A, 93B (see, for example, FIGS. 5 and 6) in the first embodiment is provided. Absent.

As shown in FIGS. 23 and 24, the lower surface 92d of the central portion 91 and the lower wall portions 92c of the current collector accommodating portions 92A and 92B is above the straight portion 20c of the upper end portion 20a of the electrode body 20. cover. Further, the curved portion 20d of the upper end portion 20a of the electrode body 20 faces the inner side surface 12b of the lid 12 without the intervention of the upper spacer 90.

When the lid 12 is pushed toward the bottom wall portion 11b of the case body 11 and the upper end portion 20a of the electrode body 20 is pressed by the upper spacer 90, the straight portion 20c is the central portion 91 and the current collector accommodating portion 92A. , The lower surface 92d with the lower wall portion 92c of 92B is pressed. On the other hand, at this time, the curved portion 20d of the end portion 20a of the electrode body 20 is not pressed by the upper spacer 90. Therefore, the curved portion 20d of the electrode body 20 is not pressed excessively strongly, and damage to the separator 23 at the curved portion 20d, damage to the positive electrode sheet 21 and the negative electrode sheet 22 and the like can be prevented.

The present invention is not limited to secondary batteries such as non-aqueous electrolyte secondary batteries including lithium ion batteries, and can be applied to various power storage elements including primary batteries and capacitors.

1 Battery 10 Exterior body 11 Case body 11a Opening 11b Bottom wall part 11c Long side wall part 11d Short side wall part 12 Lid 12a Outer side surface 12b Inner side surface 20 Electrode body 20a, 20b End part 20c Straight part 20d Curved part 21 Positive electrode sheet 22 Electrode sheet 23 Separator 23a Bent part 24 Positive metal foil 24a Uncoated part 24b Protrusion 25 Positive electrode active material layer 26 Negative metal foil 26a Uncoated part 26b Protrusion 27 Negative electrode active material layer 28 Positive electrode current collection tab 29 Negative electrode current collection Tab 30 Insulation sheet 40 Bottom spacer 50A, 50B External terminal 51A, 51B Plate-shaped part 52 Shaft part 52a Diameter expansion part 53 Rivet 53a Jaw part 53b Diameter expansion part 60A, 60B Current collector 61A, 61B Welded part 62A, 62B Cover Clamping parts 70A, 70B Upper packing 80A, 80B Lower packing 90 Upper spacer 91 Central part 91a Opening 92A, 92B Current collector accommodating part 92a Side wall part 92b Upper wall part 92c Lower wall part 92d Lower surface 92e Gap 93A, 93B Tightening part arrangement part 93a Bottom wall part 93b Inner peripheral wall part 93c Outer peripheral wall part 93d Lower surface 93e Base part 93f Recession 94 Inclined surface

Claims (7)

An electrode body whose ends have a pair of straight portions facing each other and a pair of curved portions facing each other so as to connect these straight portions.
A case body having a bottom portion and an opening facing the bottom portion, and a lid for closing the opening of the case body are provided, and the electrode body is housed in the case body with the end portion facing the lid. With the exterior
An upper spacer arranged between the lid and the end portion of the electrode body and having a first portion covering the pair of straight portions of the electrode body and a second portion covering the curved portion of the electrode body. With and
The amount of protrusion of the lid of the first part from the most part of the case body side is smaller than the amount of protrusion of the lid of the second part from the most part of the case body side.
The electrode body includes a positive electrode sheet and a negative electrode sheet each comprising a metal foil and an active material layer formed on the metal foil, a separator, and a bent portion in which an edge portion of the separator is bent.
The electrode body is formed by superimposing the positive electrode sheet and the negative electrode sheet so as to interpose the separator and winding the electrode body around a winding axis.
The bent portion is formed by bending the edge portion of the separator toward the winding shaft .
In the bent portion of the end portion of the electrode body, the amount of protrusion of the edge portion of the separator facing the second portion in the curved portion is the protrusion amount of the edge portion facing the first portion in the straight portion. Greater than the amount of protrusion of the edge of
Power storage element. The power storage element according to claim 1, wherein the first portion of the upper spacer is a flat surface. The second portion of the upper spacer includes a third portion which is a flat surface and a fourth portion which is recessed from the third portion toward the lid and has a contour conforming to the curved portion of the electrode body. , The power storage element according to claim 1. The positive electrode sheet and the negative electrode sheet each include a plurality of protrusions of the metal foil protruding from the uncoated portion where the active material layer is not provided.
In the electrode body, the plurality of protrusions of the positive electrode sheet are overlapped with each other to form a positive electrode current collecting tab protruding from the separator, and the plurality of protrusions of the negative electrode sheet are overlapped with each other. The positive electrode sheet and the negative electrode sheet are overlapped with the separator interposed therebetween and wound around the winding axis so as to form a negative electrode current collecting tab protruding from the separator. The power storage element according to any one of claims 1 to 3, wherein the positive electrode current collecting tab and the negative electrode current collecting tab are arranged on one side of the pair of straight portions. An electrode body whose ends have a pair of straight portions facing each other and a pair of curved portions facing each other so as to connect these straight portions.
A case body having a bottom portion and an opening facing the bottom portion, and a lid for closing the opening of the case body are provided, and the electrode body is housed in the case body with the end portion facing the lid. With the exterior
It is provided with an upper spacer which is arranged between the lid and the end portion of the electrode body and covers only the straight portion of the electrode body.
The electrode body includes a positive electrode sheet and a negative electrode sheet each comprising a metal foil and an active material layer formed on the metal foil, a separator, and a bent portion in which an edge portion of the separator is bent.
The electrode body is formed by superimposing the positive electrode sheet and the negative electrode sheet so as to interpose the separator and winding the electrode body around a winding axis.
The bent portion is formed by bending the edge portion of the separator toward the winding shaft .
In the bent portion of the end portion of the electrode body, the protrusion amount of the edge portion of the separator in the curved portion is larger than the protrusion amount of the edge portion of the separator facing the upper spacer in the straight portion. large,
Power storage element. An electrode body having a pair of straight portions whose ends face each other and a pair of curved portions facing each other so as to connect these straight portions is prepared.
The electrode body includes a positive electrode sheet and a negative electrode sheet each comprising a metal foil and an active material layer formed on the metal foil, a separator, and a bent portion in which an edge portion of the separator is bent.
The electrode body is formed by superimposing the positive electrode sheet and the negative electrode sheet so as to interpose the separator and winding the electrode body around a winding axis.
The bent portion is formed by bending the edge portion of the separator toward the winding shaft.
The electrode body is assembled to the lid with an upper spacer interposed therebetween, and the upper spacer has a first portion of the electrode body facing the straight portion and a second portion of the electrode body facing the curved portion. The amount of protrusion of the lid from the most case body side of the first part is smaller than the amount of protrusion of the lid from the most case body side of the second part.
In the bent portion of the end portion of the electrode body, the amount of protrusion of the edge portion of the separator facing the second portion in the curved portion is the protrusion amount of the edge portion facing the first portion in the straight portion. Greater than the amount of protrusion of the edge of
The electrode body is inserted into the case body through the opening of the case body, and the electrode body is inserted into the case body.
By pushing the lid toward the opening of the case body, the first portion of the upper spacer is pressed against the straight portion of the end portion of the electrode body, and the second portion of the upper spacer is pressed. A method for manufacturing a power storage element, which presses against the curved portion of the end portion of the electrode body. An electrode body having a pair of straight portions whose ends face each other and a pair of curved portions facing each other so as to connect these straight portions is prepared.
The electrode body includes a positive electrode sheet and a negative electrode sheet each comprising a metal foil and an active material layer formed on the metal foil, a separator, and a bent portion in which an edge portion of the separator is bent.
The electrode body is formed by superimposing the positive electrode sheet and the negative electrode sheet so as to interpose the separator and winding the electrode body around a winding axis.
The bent portion is formed by bending the edge portion of the separator toward the winding shaft.
The electrode body is assembled to the lid with the upper spacer interposed therebetween, and the upper spacer includes only a portion of the electrode body facing the straight portion.
In the bent portion of the end portion of the electrode body, the protrusion amount of the edge portion of the separator in the curved portion is larger than the protrusion amount of the edge portion of the separator facing the upper spacer in the straight portion. big,
A method for manufacturing a power storage element, in which the upper spacer is pressed against the straight line portion of the end portion of the electrode body by pushing the lid toward the opening of the case body.

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