JP2021026982A - Electrode sheet - Google Patents

Abstract

To provide an electrode sheet in which wrinkles on an exposed part can be suppressed.SOLUTION: In a shorter-side direction of long sheet-like positive electrode metal foil 21, a positive electrode sheet 20 has: a positive electrode coated part 23 in which the positive electrode metal foil 21 and a positive electrode active material layer 22 are present; and a positive electrode exposed part 25 in which the positive electrode active material layer 22 is absent, and from which the positive electrode metal foil 21 is exposed. The positive electrode sheet 20 has: a groove 27 penetrating the positive electrode exposed part 25; and a reinforcement layer 28 present on both faces of the positive electrode exposed part 25. The groove 27 has an inner end part 27a on an end located on the positive electrode active material layer 22 side in the shorter-side direction of the positive electrode metal foil 21. In the shorter-side direction of the positive electrode metal foil 21, the reinforcement layer 28 is located between the inner end part 27a and the positive electrode coated part 23.SELECTED DRAWING: Figure 4

Description

The present invention has a coated portion in which the metal foil and the active material layer are present, and an exposed portion in which the active material layer is not present and the metal foil is exposed in the lateral direction of the long sheet-shaped metal foil. Regarding electrode sheets.

Conventionally, electrode sheets used in power storage devices such as lithium ion secondary batteries have been known. The electrode sheet has a coated portion in which the metal foil and the active material layer are present and an exposed portion in which the active material layer is not present and the metal foil is exposed in the lateral direction of the long sheet-shaped metal foil. ..

Patent Document 1 discloses a method for manufacturing an electrode sheet. The method for producing an electrode sheet includes a coating step of applying an active material mixture, which is a precursor of an active material layer, to at least one side of a long sheet-shaped metal foil. An electrode sheet precursor having a coated part precursor in which the active material mixture is coated on at least one surface of the metal foil by the coating process, and an exposed part in which the active material mixture is not applied and the metal foil is exposed. The body is formed. Further, the method for manufacturing the electrode sheet includes a pressing step of passing the electrode sheet precursor between the pair of press rolls and pressing the coating portion precursor. In the pressing process, the density of the active material in the active material mixture is increased to a desired density. As a result, the active material mixture becomes the active material layer, and the coating part precursor becomes the coating part. Further, the electrode sheet precursor becomes an electrode sheet.

JP-A-2018-014220

By the way, in the above-mentioned pressing process, the pressing force by the press roll acts on the coated portion, but the pressing force by the press roll hardly acts on the exposed portion. Therefore, the amount of elongation of the exposed portion of the metal leaf is smaller than the amount of elongation of the portion of the metal foil that constitutes the coated portion. If the amount of elongation of the metal leaf differs between the coated portion and the exposed portion in the lateral direction of the metal foil, wrinkles may occur in the exposed portion.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electrode sheet capable of suppressing wrinkles in an exposed portion.

The electrode sheet for solving the above problems has a coating portion in which the metal foil and the active material layer are present and the active material layer is not present in the lateral direction of the long sheet-shaped metal foil. An electrode sheet having an exposed portion where the metal foil is exposed, and having a penetrating portion penetrating the exposed portion and a reinforcing layer existing on at least one surface of the exposed portion. The reinforcing layer has an inner end portion at an end located on the active material layer side in the lateral direction of the metal foil, and the reinforcing layer is located between the inner end portion and the coating portion in the lateral direction of the metal foil. The gist is that it is located in.

According to this, the difference between the amount of elongation of the portion constituting the coated portion in the metal foil and the amount of elongation of the portion constituting the exposed portion in the metal foil is absorbed by the penetrating portion. Therefore, wrinkles in the exposed portion can be suppressed.

Further, with respect to the electrode sheet, it is preferable that the penetrating portion is a groove that opens on the side opposite to the coated portion in the lateral direction of the metal foil.
Further, with respect to the electrode sheet, it is preferable that the penetrating portion is a hole.

When the penetrating portion is a groove, the exposed portion is divided and separated at the portion where the groove is formed. On the other hand, by making the penetrating portion a hole, it is possible to prevent the exposed portion from being separated. Therefore, the ease of handling of the exposed portion is not impaired.

Further, with respect to the electrode sheet, it is preferable that the inner end portion has a curved shape that is recessed toward the coated portion side in the lateral direction of the metal foil.
According to this, it is possible to prevent the penetrating portion from extending toward the coated portion.

According to the present invention, wrinkles in the exposed portion can be suppressed.

An exploded perspective view of the secondary battery of the embodiment. The plan view of the electrode assembly of an embodiment. (A) is a plan view of the positive electrode sheet, and (b) is a plan view of the negative electrode sheet. An enlarged plan view of the electrode sheet of the embodiment. Sectional drawing of the secondary battery of embodiment. The plan view which shows the manufacturing method of an electrode sheet. (A) is a plan view showing a manufacturing method of an electrode sheet, and (b) is a sectional view showing a manufacturing method of an electrode sheet. An enlarged plan view of another example electrode sheet. An enlarged plan view of another example electrode sheet. An enlarged plan view of another example electrode sheet.

Hereinafter, an embodiment in which the electrode sheet is embodied will be described with reference to FIGS. 1 to 7.
As shown in FIG. 1, the secondary battery 10 as a power storage device includes a rectangular parallelepiped case 11, an electrode assembly 12 housed in the case 11, and an electrolytic solution (not shown) housed in the case 11. The case 11 has a bottomed square tubular case body 13 and a plate-shaped lid 14 that closes the opening 13a of the case body 13. The case body 13 was erected from a rectangular bottom wall 13b, a pair of long side walls 13c erected from a pair of long side edges of the bottom wall 13b, and a pair of short side edges of the bottom wall 13b. It has a pair of short side walls 13d. Therefore, the secondary battery 10 of the present embodiment is a square battery having a square appearance. The case body 13 and the lid 14 form a wall portion of the case 11. The case body 13 and the lid 14 are made of metal such as aluminum. Further, the secondary battery 10 of the present embodiment is a lithium ion secondary battery.

As shown in FIG. 2, the electrode assembly 12 includes a positive electrode sheet 20 as a long sheet-shaped electrode sheet, a negative electrode sheet 30 as a long sheet-shaped electrode sheet, and two long sheet-shaped electrodes. The separator 40 is provided.

As shown in FIG. 3A, the positive electrode electrode sheet 20 has a positive electrode metal foil 21 as a metal foil and a positive electrode active material layer 22 as an active material layer. The positive electrode metal foil 21 of the present embodiment is an aluminum foil. The positive electrode metal foil 21 has a long sheet-shaped positive electrode main body 21a and a plurality of positive electrode tabs 21b protruding from the positive electrode main body 21a. In the following, the longitudinal direction of the positive electrode main body 21a is the longitudinal direction of the positive electrode metal leaf 21, and the lateral direction of the positive electrode main body 21a is the lateral direction of the positive electrode metal leaf 21. The longitudinal direction of the positive electrode body 21a is also the longitudinal direction of the positive electrode sheet 20, and the lateral direction of the positive electrode body 21a is also the lateral direction of the positive electrode sheet 20. The positive electrode body 21a is located along the longitudinal direction and on the side opposite to the first edge 211 and the first edge 211, which is the edge on which the positive electrode tab 21b protrudes. It has a second edge portion 212 which is an edge portion to be formed. The shape of the positive electrode tab 21b is the same for all the positive electrode tabs 21b, and is rectangular in this embodiment.

As shown in FIG. 2, a plurality of positive electrode active material layers 22 are present on both sides of the positive electrode main body 21a. The plurality of positive electrode active material layers 22 existing on each surface of the positive electrode main body 21a are arranged at intervals in the longitudinal direction of the positive electrode main body 21a. The shape of the positive electrode active material layer 22 is the same for all the positive electrode active material layers 22, and is rectangular in the present embodiment. The position of each edge of the positive electrode active material layer 22 existing on one surface of the positive electrode main body 21a coincides with the position of each edge of the positive electrode active material layer 22 existing on the other surface of the positive electrode main body 21a. There is.

As shown in FIG. 3A, the longitudinal direction of each positive electrode active material layer 22 coincides with the longitudinal direction of the positive electrode metal foil 21, and the lateral direction of each positive electrode active material layer 22 is the short length of the positive electrode metal foil 21. It matches the hand direction. The longitudinal dimension of the positive electrode active material layer 22 is the same for all the positive electrode active material layers 22. The dimensions of the positive electrode active material layer 22 in the lateral direction are the same for all the positive electrode active material layers 22. In the present embodiment, the dimension of the positive electrode active material layer 22 in the lateral direction is shorter than the dimension of the positive electrode main body 21a in the lateral direction of the positive electrode metal foil 21. Each positive electrode active material layer 22 has a first edge portion 221 on one of the pair of long edge portions along the longitudinal direction located on the first edge portion 211 side of the positive electrode main body portion 21a, and is a positive electrode main body. The second edge portion 222 is provided at the other edge portion located on the opposite side of the portion 21a from the first edge portion 211. The first edge portion 211 of the positive electrode main body portion 21a protrudes from the first edge portion 221 of each positive electrode active material layer 22 in the lateral direction of the positive electrode metal foil 21. The second edge portion 212 of the positive electrode main body portion 21a is along the second edge portion 222 of each positive electrode active material layer 22.

The positive electrode electrode sheet 20 has a plurality of positive electrode coated portions 23 having positive electrode active material layers 22 on both sides of the positive electrode main body portion 21a, and positive electrode coating portions 23 alternately present in the longitudinal direction of the positive electrode metal foil 21. It has a coating unit 24. In the present embodiment, the positive electrode sheet 20 has six positive electrode coated portions 23 and five positive electrode uncoated portions 24.

The positive electrode uncoated portion 24 is a portion where the positive electrode active material layer 22 does not exist and the positive electrode main body portion 21a is exposed. The positive electrode uncoated portion 24 is located between the positive electrode coated portion 23 and the positive electrode coated portion 23 in the longitudinal direction of the positive electrode metal foil 21, and the first edge portion 221 of the positive electrode active material layer 22 in the lateral direction of the positive electrode metal foil 21. It is located between the positive electrode active material layer 22 and the second edge portion 222 of the positive electrode active material layer 22.

The width of the positive electrode uncoated portion 24 in the longitudinal direction of the positive electrode metal foil 21 differs for each positive electrode uncoated portion 24. Specifically, the width of the positive electrode uncoated portion 24 is as small as the positive electrode uncoated portion 24 closest to the first end 21s in the longitudinal direction of the positive electrode metal foil 21, and is located at the second end 21e of the positive electrode metal foil 21 in the longitudinal direction. The closest positive electrode uncoated portion 24 is larger. That is, the width of the positive electrode uncoated portion 24 is widened from the positive electrode uncoated portion 24 closest to the first end 21s in the longitudinal direction of the positive electrode metal foil 21 to the positive electrode uncoated portion 24 closest to the second end 21e. It is getting bigger and bigger.

The positive electrode electrode sheet 20 has a positive electrode exposed portion as an exposed portion in which the positive electrode active material layer 22 does not exist at the end of the positive electrode metal foil 21 on the first edge portion 211 side in the lateral direction and the positive electrode metal foil 21 is exposed. Has 25. In the present embodiment, the positive electrode exposed portion 25 is composed of a positive electrode band-shaped portion 26 and a positive electrode tab 21b. The positive electrode electrode sheet 20 has a positive electrode coating portion 23 and a positive electrode exposed portion 25 in the lateral direction of the positive electrode metal foil 21.

The positive electrode strip-shaped portion 26 exists over the entire longitudinal direction of the positive electrode metal foil 21. The positive electrode strip-shaped portion 26 is located between the first edge portion 221 of the positive electrode active material layer 22 and the first edge portion 211 of the positive electrode main body portion 21a in the lateral direction of the positive electrode metal foil 21.

Each positive electrode tab 21b protrudes from the first edge portion 211 of the portion of the positive electrode main body portion 21a that constitutes the positive electrode coating portion 23. That is, each positive electrode tab 21b is arranged at a position corresponding to each positive electrode coating portion 23 in the longitudinal direction of the positive electrode metal foil 21. Further, in each positive electrode tab 21b, the positive electrode tab 21b located closer to one end in the longitudinal direction of the positive electrode active material layer 22 and the positive electrode tab 21b located closer to the other end in the longitudinal direction of the positive electrode active material layer 22 are positive electrode metal foils. It is arranged so as to exist alternately in the longitudinal direction of 21.

As shown in FIG. 4, the positive electrode sheet 20 penetrates each positive electrode tab 21b and has a groove 27 as a penetrating portion that opens on the side opposite to the positive electrode coating portion 23 in the lateral direction of the positive electrode metal foil 21. Have. In the present embodiment, each groove 27 has a slit shape extending linearly along the lateral direction of the positive electrode main body 21a. Further, in the lateral direction of the positive electrode metal foil 21, the length of each groove 27 is shorter than the length of each positive electrode tab 21b. Each groove 27 does not exist in the positive electrode band-shaped portion 26. Each groove 27 has an inner end portion 27a at an end portion located on the positive electrode coating portion 23 side in the lateral direction of the positive electrode metal foil 21. The positive electrode tab 21b is divided into two in the longitudinal direction of the positive electrode metal foil 21 at the portion where the groove 27 is formed.

The positive electrode sheet 20 has reinforcing layers 28 on both sides of each positive electrode tab 21b. The reinforcing layer 28 of this embodiment is made of resin. Further, the reinforcing layer 28 exists in a circular shape centered on the inner end portion 27a of the groove 27. Therefore, a part of the reinforcing layer 28 is located between the groove 27 and the positive electrode coating portion 23 in the lateral direction of the positive electrode metal foil 21.

As shown in FIG. 3B, the negative electrode electrode sheet 30 has a negative electrode metal foil 31 as a metal foil and a negative electrode active material layer 32 as an active material layer. The negative electrode metal foil 31 of this embodiment is a copper foil. The negative electrode metal foil 31 has a long sheet-shaped negative electrode main body 31a and a plurality of negative electrode tabs 31b protruding from the negative electrode main body 31a. In the following, the longitudinal direction of the negative electrode body 31a is defined as the longitudinal direction of the negative electrode metal foil 31, and the lateral direction of the negative electrode body 31a is defined as the lateral direction of the negative electrode metal foil 31. The longitudinal direction of the negative electrode body 31a is also the longitudinal direction of the negative electrode sheet 30, and the lateral direction of the negative electrode body 31a is also the lateral direction of the negative electrode sheet 30. The negative electrode body 31a is located along the longitudinal direction and on the side opposite to the first edge 311 and the first edge 311 which is the edge on which the negative electrode tab 31b protrudes. It has a second edge portion 312 which is an edge portion to be formed. The shape of the negative electrode tab 31b is the same for all the negative electrode tabs 31b, and is rectangular in this embodiment.

As shown in FIG. 2, a plurality of negative electrode active material layers 32 are present on both sides of the negative electrode main body 31a. The plurality of negative electrode active material layers 32 existing on each surface of the negative electrode main body 31a are arranged at intervals in the longitudinal direction of the negative electrode main body 31a. The shape of the negative electrode active material layer 32 is the same for all the negative electrode active material layers 32, and is rectangular in the present embodiment. The position of each edge of the negative electrode active material layer 32 existing on one surface of the negative electrode main body 31a coincides with the position of each edge of the negative electrode active material layer 32 existing on the other surface of the negative electrode main body 31a. There is.

As shown in FIG. 3B, the longitudinal direction of each negative electrode active material layer 32 coincides with the longitudinal direction of the negative electrode metal foil 31, and the lateral direction of each negative electrode active material layer 32 is the short length of the negative electrode metal foil 31. It matches the hand direction. The width of the negative electrode active material layer 32 in the longitudinal direction is the same for all the negative electrode active material layers 32. In the present embodiment, the width of the negative electrode active material layer 32 in the longitudinal direction is larger than the width of the positive electrode active material layer 22 in the longitudinal direction. Further, the dimensions of each negative electrode active material layer 32 in the lateral direction are the same for all the negative electrode active material layers 32. In the present embodiment, the dimension of the negative electrode active material layer 32 in the lateral direction is shorter than the dimension of the negative electrode main body 31a in the lateral direction of the negative electrode metal foil 31. Each negative electrode active material layer 32 has a first edge portion 321 on one of the pair of long edge portions along the longitudinal direction located on the first edge portion 311 side of the negative electrode main body portion 31a, and has a negative electrode main body. The second edge portion 322 is provided at the other edge portion located on the opposite side of the first edge portion 311 of the portion 31a. The first edge portion 311 of the negative electrode main body portion 31a protrudes from the first edge portion 321 of each negative electrode active material layer 32 in the lateral direction of the negative electrode metal foil 31. The second edge portion 312 of the negative electrode main body portion 31a is along the second edge portion 322 of each negative electrode active material layer 32.

The negative electrode electrode sheet 30 has a plurality of negative electrode coated portions 33 in which negative electrode active material layers 32 are present on both sides of the negative electrode main body portion 31a, and negative electrode coating portions 33 alternately present in the longitudinal direction of the negative electrode metal foil 31. It has a coating unit 34. In the present embodiment, the negative electrode electrode sheet 30 has seven negative electrode coated portions 33 and six negative electrode uncoated portions 34.

The negative electrode uncoated portion 34 is a portion where the negative electrode active material layer 32 does not exist and the negative electrode main body portion 31a is exposed. The negative electrode uncoated portion 34 is located between the negative electrode coated portion 33 in the longitudinal direction of the negative electrode metal foil 31 and the first edge portion 321 of the negative electrode active material layer 32 in the lateral direction of the negative electrode metal foil 31. It is located between the negative electrode active material layer 32 and the second edge portion 322 of the negative electrode active material layer 32.

The width of the negative electrode uncoated portion 34 in the longitudinal direction of the negative electrode metal foil 31 differs for each negative electrode uncoated portion 34. Specifically, the width of the negative electrode uncoated portion 34 is as small as the negative electrode uncoated portion 34 closest to the first end 31s in the longitudinal direction of the negative electrode metal foil 31, and is located at the second end 31e of the negative electrode metal foil 31 in the longitudinal direction. The nearest negative electrode uncoated portion 34 is larger. That is, the width of the negative electrode uncoated portion 34 from the negative electrode uncoated portion 34 closest to the first end 31s in the longitudinal direction of the negative electrode metal foil 31 to the negative electrode uncoated portion 34 closest to the second end 31e It is getting bigger and bigger.

The negative electrode electrode sheet 30 has a negative electrode exposed portion as an exposed portion in which the negative electrode active material layer 32 does not exist at the end portion of the negative electrode metal foil 31 on the first edge portion 311 side in the lateral direction and the negative electrode metal foil 31 is exposed. Has 35. In the present embodiment, the negative electrode exposed portion 35 is composed of a negative electrode band-shaped portion 36 and a negative electrode tab 31b. The negative electrode electrode sheet 30 has a negative electrode coating portion 33 and a negative electrode exposed portion 35 in the lateral direction of the negative electrode metal foil 31.

The negative electrode band-shaped portion 36 exists over the entire longitudinal direction of the negative electrode metal foil 31. The negative electrode band-shaped portion 36 is located between the first edge portion 321 of the negative electrode active material layer 32 and the first edge portion 311 of the negative electrode main body portion 31a in the lateral direction of the negative electrode metal foil 31.

Each negative electrode tab 31b protrudes from the first edge portion 311 of the portion of the negative electrode main body 31a that constitutes the negative electrode coating portion 33. That is, each negative electrode tab 31b is arranged at a position corresponding to each negative electrode coating portion 33 in the longitudinal direction of the negative electrode metal foil 31. Further, in each negative electrode tab 31b, the negative electrode tab 31b located near one end in the longitudinal direction of the negative electrode active material layer 32 and the negative electrode tab 31b located near the other end in the longitudinal direction of the negative electrode active material layer 32 are negative electrode metal foils. It is arranged so as to exist alternately in the longitudinal direction of 31.

As shown in FIG. 4, the negative electrode electrode sheet 30 penetrates each negative electrode tab 31b and has a groove 37 as a penetrating portion that opens on the side opposite to the negative electrode coating portion 33 in the lateral direction of the negative electrode metal foil 31. Have. In the present embodiment, each groove 37 has a slit shape extending linearly along the lateral direction of the negative electrode main body 31a. Further, in the lateral direction of the negative electrode metal foil 31, the length of each groove 37 is shorter than the length of each negative electrode tab 31b. Each groove 37 does not exist in the negative electrode band-shaped portion 36. Each groove 37 has an inner end portion 37a at an end portion located on the negative electrode coating portion 33 side in the lateral direction of the negative electrode metal foil 31. The negative electrode tab 31b is divided into two in the longitudinal direction of the negative electrode metal foil 31 at the portion where the groove 37 is formed.

The negative electrode electrode sheet 30 has reinforcing layers 38 on both sides of each negative electrode tab 31b. The reinforcing layer 38 of this embodiment is made of resin. Further, the reinforcing layer 38 exists in a circular shape centered on the inner end portion 37a of the groove 37. Therefore, a part of the reinforcing layer 38 is located between the groove 37 and the negative electrode coating portion 33 in the lateral direction of the negative electrode metal foil 31.

Each separator 40 is interposed between the positive electrode sheet 20 and the negative electrode sheet 30. Each separator 40 is a porous membrane through which lithium ions can pass. The longitudinal dimension of each separator 40 is longer than the longitudinal dimension of the negative electrode metal foil 31, and the lateral dimension of each separator 40 is the dimension of the negative electrode body 31a in the lateral direction of the negative electrode metal foil 31. It's almost the same.

In the electrode assembly 12, one of the positive electrode sheet 20 and the two separators 40, the negative electrode sheet 30, and the other of the two separators 40 are laminated in this order and wound in a spiral shape. It is formed by The winding direction of the positive electrode sheet 20, the negative electrode sheet 30, and each separator 40 coincides with the longitudinal direction of the positive electrode sheet 20, the negative electrode sheet 30, and each separator 40. The electrode assembly 12 has a layered structure in which a positive electrode sheet 20 and a negative electrode sheet 30 are laminated via a separator 40.

The first end 21s of the positive electrode metal foil 21 and the first end 31s of the negative electrode metal foil 31 are located on the winding start side, and the second end 21e of the positive electrode metal foil 21 and the second end 31e of the negative electrode metal foil 31 are wound. Located on the end side. In other words, the first end 21s of the positive electrode metal foil 21 and the first end 31s of the negative electrode metal foil 31 are located on the inner peripheral side of the electrode assembly 12, and the second end 21e of the positive electrode metal leaf 21 and the negative electrode metal foil 31 The second end 31e of the above is located on the outer peripheral side of the electrode assembly 12.

The electrode assembly 12 has a coating laminated portion 12a in which a positive electrode coating portion 23 and a negative electrode coating portion 33 are alternately laminated via a separator 40. The direction in which the positive electrode coating portion 23 and the negative electrode coating portion 33 are laminated is defined as the lamination direction.

In the coating laminated portion 12a, in the positive electrode coating portion 23 and the negative electrode coating portion 33 adjacent to each other in the lamination direction, the positive electrode activity located on the inner peripheral side of the positive electrode active material layers 22 existing on both sides of the positive electrode main body portion 21a. The material layer 22 faces the negative electrode active material layer 32 located on the outer peripheral side of the negative electrode active material layers 32 existing on both sides of the negative electrode main body 31a via the separator 40. Further, in the positive electrode coating portion 23 and the negative electrode coating portion 33 adjacent to each other in the stacking direction, among the positive electrode active material layers 22 existing on both sides of the positive electrode main body portion 21a, the positive electrode active material layer 22 located on the outer peripheral side is the negative electrode. Of the negative electrode active material layers 32 existing on both sides of the main body 31a, the negative electrode active material layer 32 located on the inner peripheral side faces the negative electrode active material layer 32 via the separator 40. In the present embodiment, in the longitudinal direction of the positive electrode active material layer 22 and the negative electrode active material layer 32, both ends of the negative electrode active material layer 32 are located outside the both ends of the positive electrode active material layer 22.

In the present embodiment, the first end surface 121 in the stacking direction of the electrode assembly 12 is composed of the negative electrode coating portion 33 located at the first end in the stacking direction, and the second end surface 121 in the stacking direction of the electrode assembly 12. 122 is composed of a negative electrode coating portion 33 located at the second end in the stacking direction.

The positive electrode coating portion 23 located on the first end side in the stacking direction with respect to the winding shaft L and the positive electrode coating portion 23 located on the second end side in the stacking direction with respect to the winding shaft L are positive electrode metal foils. It exists alternately in the longitudinal direction of 21. In other words, of the two positive electrode coated portions 23 adjacent to each other with the positive electrode uncoated portion 24 sandwiched in the longitudinal direction of the positive electrode metal foil 21, one positive electrode coated portion 23 is in the stacking direction with respect to the winding shaft L. When it is located on the first end side, the other positive electrode coating portion 23 is located on the second end side in the stacking direction with respect to the winding shaft L.

Similarly, the negative electrode coating portion 33 located on the first end side in the stacking direction with respect to the winding shaft L and the negative electrode coating portion 33 located on the second end side in the stacking direction with respect to the winding shaft L It exists alternately in the longitudinal direction of the negative electrode metal foil 31. In other words, of the two negative electrode coated portions 33 adjacent to each other with the negative electrode uncoated portion 34 sandwiched in the longitudinal direction of the negative electrode metal foil 31, one of the negative electrode coated portions 33 is in the stacking direction with respect to the winding shaft L. When it is located on the first end side, the other negative electrode coating portion 33 is located on the second end side in the stacking direction with respect to the winding shaft L.

In the electrode assembly 12, the positive electrode tabs 21b are arranged in a row, and the negative electrode tabs 31b are arranged in a row at a position different from the position where the positive electrode tabs 21b are arranged in a row. In the present embodiment, the positive electrode tabs 21b are arranged in a row on one end side of the positive electrode active material layer 22 and the negative electrode active material layer 32 in the longitudinal direction, and each negative electrode tab 31b is the positive electrode active material layer 22 and the negative electrode active material layer 32. Line up in a row on the other end side of the longitudinal direction. As shown in FIG. 1, the electrode assembly 12 includes a positive electrode tab group 15 in which a plurality of positive electrode tabs 21b arranged in a row are gathered and laminated, and a plurality of negative electrode tabs arranged in a row at positions different from the positive electrode tabs 21b. It has a negative electrode tab group 16 in which 31b is gathered and laminated.

The electrode assembly 12 includes a first uncoated laminated portion 12b located on one end side of the coated laminated portion 12a in the longitudinal direction of the positive electrode active material layer 22 and the negative electrode active material layer 32, and the positive electrode active material layer 22 and the negative electrode. It has a second uncoated laminated portion 12c located on the other end side of the coated laminated portion 12a in the longitudinal direction of the active material layer 32. The first uncoated laminated portion 12b and the second uncoated laminated portion 12c are portions in which the positive electrode uncoated portion 24 and the negative electrode uncoated portion 34 are laminated via the separator 40, respectively.

The positive electrode uncoated portion 24 constituting the first uncoated laminated portion 12b and the positive electrode uncoated portion 24 forming the second uncoated laminated portion 12c exist alternately in the longitudinal direction of the positive electrode metal foil 21. To do. In other words, of the two positive electrode uncoated portions 24 adjacent to each other with the positive electrode coated portion 23 in the longitudinal direction of the positive electrode metal foil 21, one positive electrode uncoated portion 24 forms the first uncoated laminated portion 12b. When configured, the other positive electrode uncoated portion 24 constitutes the second uncoated laminated portion 12c.

Similarly, the negative electrode uncoated portion 34 constituting the first uncoated laminated portion 12b and the negative electrode uncoated portion 34 forming the second uncoated laminated portion 12c are formed in the longitudinal direction of the negative electrode metal foil 31. It exists alternately. In other words, of the two negative electrode uncoated portions 34 adjacent to each other with the negative electrode coated portion 33 in the longitudinal direction of the negative electrode metal foil 31, one of the negative electrode uncoated portions 34 forms the first uncoated laminated portion 12b. When configured, the other negative electrode uncoated portion 34 constitutes the second uncoated laminated portion 12c.

As described above, the positive electrode sheet 20 is wound so that the first end 21s of the positive electrode metal foil 21 is on the winding start side. Therefore, the width of the positive electrode uncoated portion 24 is as long as the positive electrode exposed portion 25 located on the outer peripheral side of the first uncoated laminated portion 12b. Further, the width of the positive electrode uncoated portion 24 is as long as the positive electrode uncoated portion 24 located on the outer peripheral side in the second uncoated laminated portion 12c.

Similarly, the negative electrode electrode sheet 30 is wound so that the first end 31s of the negative electrode metal foil 31 is on the winding start side. Therefore, the width of the negative electrode uncoated portion 34 is as long as the negative electrode uncoated portion 34 located on the outer peripheral side in the first uncoated laminated portion 12b. Further, the width of the negative electrode uncoated portion 34 is as long as the negative electrode uncoated portion 34 located on the outer peripheral side in the second uncoated laminated portion 12c.

As shown in FIG. 1, the secondary battery 10 includes a positive electrode terminal structure 17 and a negative electrode terminal structure 18 for extracting electricity from the electrode assembly 12. The positive electrode terminal structure 17 has a plate-shaped positive electrode conductive member 17a joined to the positive electrode tab group 15, and a rod-shaped positive electrode terminal 17b protruding from the positive electrode conductive member 17a. The negative electrode terminal structure 18 has a plate-shaped negative electrode conductive member 18a joined to the negative electrode tab group 16 and a rod-shaped negative electrode terminal 18b protruding from the negative electrode conductive member 18a. The positive electrode terminal 17b and the negative electrode terminal 18b each penetrate the lid 14 and project to the outside of the case 11 to connect the inside and outside of the case 11. A bus bar as an external device (not shown) that electrically connects the secondary batteries 10 to each other can be fixed to the positive electrode terminal 17b and the negative electrode terminal 18b. The secondary battery 10 includes an insulating ring 19 for insulating the lid 14 from the positive electrode terminal 17b or the negative electrode terminal 18b.

As shown in FIGS. 1 and 5, the secondary battery 10 has a pressure release valve 14a on the lid 14. The pressure release valve 14a is used when the pressure inside the case 11 reaches the release pressure, which is a predetermined pressure, so that the pressure inside the case 11 does not rise too much when gas is generated inside the case 11. Cleavage. As a result, the inside and outside of the case 11 are communicated with each other, and the pressure inside the case 11 is released to the outside of the case 11. The pressure release valve 14a is located at the center of the lid 14 in the longitudinal direction. The pressure release valve 14a is arranged at a position where it does not overlap with the positive electrode conductive member 17a and the negative electrode conductive member 18a. That is, the pressure release valve 14a is arranged at a position so as not to overlap the positive electrode tab group 15 and the negative electrode tab group 16.

A method for manufacturing an electrode sheet will be described. Since the manufacturing method of the positive electrode sheet 20 and the negative electrode sheet 30 is basically the same, only the manufacturing method of the positive electrode sheet 20 will be described in detail, and the description of the manufacturing method of the negative electrode sheet 30 will be omitted.

As shown in FIG. 6, the method of manufacturing the positive electrode electrode sheet 20 is as follows: an active material which is a precursor of the positive electrode active material layer 22 on both sides of a long sheet-shaped metal foil material 210 which is a precursor of the positive electrode metal foil 21. It has a first coating step of coating the mixture 220. The active material mixture 220 is a kneaded mixture of a positive electrode active material, a conductive material, a binder, and a solvent. In the first coating step of the present embodiment, the active material mixture 220 is intermittently coated in the longitudinal direction of the metal leaf material 210. Specifically, the active material mixture 220 is coated so that the distance between the active material mixture 220s in the longitudinal direction of the metal foil material 210 matches the width of the positive electrode uncoated portion 24. The active material mixture 220 is coated so that the distance between the active material mixture 220s in the longitudinal direction of the metal foil material 210 is gradually widened or narrowed. The active material mixture 220 is not applied to both ends of the metal leaf material 210 in the lateral direction.

As a result, the coating portion precursor 230 in which the active material mixture 220 is coated on both sides of the metal foil material 210 and the positive electrode uncoated portion in which the active material mixture 220 is not applied and the metal foil material 210 is exposed. An electrode material 200 having a portion 24 and an exposed portion precursor 250 is manufactured.

The method for manufacturing the positive electrode sheet 20 includes a second coating step of coating the reinforcing layer material 280 on both surfaces of the metal foil material 210. In the second coating step of the present embodiment, the reinforcing layer material 280 is centered on the portion of the metal foil material 210 where the inner end portion 27a of the groove 27 formed later is located with respect to the portion that can be the positive electrode tab 21b. It is coated in a circular shape.

The method for producing the positive electrode sheet 20 includes a drying step of drying the active material mixture 220 and the reinforcing layer material 280 coated on both sides of the metal foil material 210. As a result, the reinforcing layer material 280 is dried to become the reinforcing layer 28. Therefore, the electrode material 200 has reinforcing layers 28 on both sides of the portion of the metal foil material 210 that becomes the positive electrode tab 21b.

The method for manufacturing the positive electrode sheet 20 includes a cutting step of cutting the electrode material 200. In the cutting step, the electrode material 200 is punched along the first cutting line L1 set to have the same shape as the outer shape of the positive electrode sheet 20 by a press die (not shown) to form the electrode sheet precursor 200a. As a result, the positive electrode metal foil 21 having the positive electrode main body 21a and the plurality of positive electrode tabs 21b is formed from the metal foil material 210. Further, from the exposed portion precursor 250, a positive electrode exposed portion 25 having a positive electrode band-shaped portion 26 and a positive electrode tab 21b is formed. In this embodiment, two electrode sheet precursors 200a are formed in the lateral direction of the electrode material 200.

Further, the method for manufacturing the positive electrode electrode sheet 20 includes a groove forming step of forming a groove 27 in each positive electrode tab 21b. In the groove forming step, the groove 27 is formed by cutting each positive electrode tab 21b along the linear second cutting line L2 by a press die (not shown). The inner end portion 27a of each groove 27 is formed so as to be located at the center of each reinforcing layer 28.

As shown in FIGS. 7 (a) and 7 (b), in the method of manufacturing the positive electrode sheet 20, the electrode sheet precursor 200a is pressed to bring the density of the active material in the active material mixture 220 to a predetermined density. Has a pressing process to raise. The pressing process is performed by the pressing apparatus 50. The press device 50 includes a pair of press rolls 51 and 52 arranged on both sides in the vertical direction with the electrode sheet precursor 200a interposed therebetween. The press rolls 51 and 52 are rotatably supported by a rotating shaft (not shown). The press rolls 51 and 52 are integrally rotated together with the rotating shaft by a drive device (not shown) connected to the rotating shaft.

The electrode sheet precursor 200a is conveyed in the longitudinal direction of the positive electrode metal foil 21 by a conveying device (not shown) so as to pass between the pair of rotating press rolls 51 and 52. As a result, the coating portion precursor 230 is pressed by the pair of press rolls 51 and 52. At this time, the direction in which the grooves 27 and 37 extend is orthogonal to the direction in which the electrode sheet precursor 200a is pressed by the pair of press rolls 51 and 52. By the pressing process, the active material mixture 220 becomes the positive electrode active material layer 22, and the coating part precursor 230 becomes the positive electrode coating part 23. Further, the electrode sheet precursor 200a becomes a positive electrode sheet 20.

The operation of this embodiment will be described.
In the pressing step, the portion of the positive electrode metal leaf 21 that constitutes the positive electrode coating portion 23 is pressed, whereas the portion of the positive electrode metal foil 21 that constitutes the positive electrode exposed portion 25 is not pressed. Therefore, the amount of elongation of the portion of the positive electrode metal leaf 21 that constitutes the positive electrode exposed portion 25 is smaller than the amount of elongation of the portion of the positive electrode metal foil 21 that constitutes the positive electrode coating portion 23. That is, there is a difference in the amount of elongation of the positive electrode metal leaf 21 in the lateral direction of the positive electrode metal leaf 21. Such a difference in the amount of elongation of the positive electrode metal foil 21 is absorbed by the groove 27 formed in the positive electrode tab 21b.

Similarly, in the pressing step, the portion of the negative electrode metal leaf 31 that constitutes the negative electrode coating portion 33 is pressed, whereas the portion of the negative electrode metal foil 31 that constitutes the negative electrode exposed portion 35 is not pressed. Therefore, the amount of elongation of the portion of the negative electrode metal foil 31 that constitutes the negative electrode exposed portion 35 is smaller than the amount of elongation of the portion of the negative electrode metal foil 31 that constitutes the negative electrode coating portion 33. That is, there is a difference in the amount of elongation of the negative electrode metal leaf 31 in the lateral direction of the negative electrode metal leaf 31. Such a difference in the amount of elongation of the negative electrode metal foil 31 is absorbed by the groove 37 formed in the negative electrode tab 31b.

The effect of this embodiment will be described.
(1) The difference in the amount of elongation of the positive electrode metal foil 21 generated during the pressing step is absorbed by the groove 27 formed in the positive electrode tab 21b. Therefore, the wrinkles of the positive electrode exposed portion 25 can be suppressed. Similarly, the difference in the amount of elongation of the negative electrode metal foil 31 that occurs during the pressing process is absorbed by the groove 37 formed in the negative electrode tab 31b. Therefore, wrinkles in the negative electrode exposed portion 35 can be suppressed.

(2) The positive electrode metal leaf 21 is reinforced by the reinforcing layer 28 existing between the groove 27 and the positive electrode coating portion 23 in the lateral direction of the positive electrode metal leaf 21. Therefore, the groove 27 is suppressed from extending toward the positive electrode coated portion 23 side. Therefore, it is possible to suppress the tearing of the portion of the positive electrode metal foil 21 that constitutes the positive electrode coating portion 23, which may occur due to the extension of the groove 27. As a result, it is possible to prevent the positive electrode active material layer 22 from falling off due to the tearing of the positive electrode metal leaf 21.

Similarly, the negative electrode metal foil 31 is reinforced by the reinforcing layer 38 existing between the groove 37 and the negative electrode coating portion 33 in the lateral direction of the negative electrode metal foil 31. Therefore, the groove 37 is prevented from extending toward the negative electrode coated portion 33 side. Therefore, it is possible to suppress the tearing of the portion of the negative electrode metal foil 31 that constitutes the negative electrode coating portion 33, which may occur due to the extension of the groove 37. As a result, it is possible to prevent the negative electrode active material layer 32 from falling off due to the tearing of the negative electrode metal foil 31.

(3) As will be described later, as one of the methods for suppressing the grooves 27 and 37 from extending toward the positive electrode coated portion 23 side or the negative electrode coated portion 33 side, for example, the inner end portions of the grooves 27 and 37 It is conceivable to form 27a and 37a as circular holes. In this case, the area of the positive electrode tab 21b or the negative electrode tab 31b is reduced by the amount of the circular hole portion, so that the electrical resistance of the positive electrode tab 21b or the negative electrode tab 31b is increased. On the other hand, in the present embodiment, by forming the reinforcing layers 28 and 38 on the positive electrode tab 21b or the negative electrode tab 31b, the grooves 27 and 37 are formed on the positive electrode coating portion 23 without changing the shapes of the grooves 27 and 37. It is possible to suppress the extension to the side or the negative electrode coating portion 33 side. Therefore, the electrical resistance of the positive electrode tab 21b or the negative electrode tab 31b does not increase.

(4) The positive electrode metal foil 21 or the negative electrode metal foil 31 is pressed in the longitudinal direction by a pair of press rolls 51 and 52. That is, the amount of elongation in the longitudinal direction of the positive electrode metal leaf 21 is larger than the amount of elongation in the lateral direction. Therefore, by forming the grooves 27 and 37 extending in the direction orthogonal to the pressing direction of the electrode sheet precursor 200a, the grooves 27 and 37 extending in parallel with the pressing direction of the electrode sheet precursor 200a are formed. Wrinkles in the positive electrode exposed portion 25 or the negative electrode exposed portion 35 can be further suppressed as compared with the case of forming.

(5) The pressure release valve 14a is arranged between the positive electrode conductive member 17a and the negative electrode conductive member 18a so as not to overlap the positive electrode conductive member 17a and the negative electrode conductive member 18a. Therefore, when the pressure release valve 14a is operating, when the gas inside the case 11 is released to the outside of the case 11 via the pressure release valve 14a, the gas flow flows through the positive electrode conductive member 17a and the negative electrode conductive member 18a. It becomes difficult to be disturbed by. Therefore, the gas inside the case 11 can be smoothly released to the outside of the case 11.

This embodiment can be modified and implemented as follows. The present embodiment and modified examples can be implemented in combination with each other within a technically consistent range.
○ If either one of the positive electrode exposed portion 25 and the negative electrode exposed portion 35 has grooves 27 and 37, the other may not have grooves.

For example, aluminum, which is the material of the positive electrode metal leaf 21, is a metal softer than copper, which is the material of the negative electrode metal leaf 31. Therefore, the difference in the amount of elongation between the portion of the positive electrode metal leaf 21 that constitutes the positive electrode coating portion 23 and the portion that constitutes the positive electrode exposed portion 25 is the difference between the portion that constitutes the negative electrode coating portion 33 and the negative electrode of the negative electrode metal foil 31. It is larger than the difference in the amount of elongation from the portion constituting the exposed portion 35. Therefore, the positive electrode exposed portion 25 is more likely to be wrinkled than the negative electrode exposed portion 35. Based on this, the wrinkles of the positive electrode exposed portion 25 may be suppressed by forming the groove 27 only in the positive electrode exposed portion 25.

Further, for example, the electrical resistivity of aluminum, which is the material of the positive electrode metal foil 21, is higher than the electrical resistivity of copper, which is the material of the negative electrode metal foil 31. Therefore, assuming that the shape and thickness of the positive electrode tab 21b are the same as the shape and thickness of the negative electrode tab 31b, the electric resistance of the positive electrode tab 21b is larger than the electric resistance of the negative electrode tab 31b. For example, as a method for reducing the difference between the electric resistance of the positive electrode tab 21b and the electric resistance of the negative electrode tab 31b, the dimensions of the positive electrode tab 21b in the longitudinal direction of the positive electrode metal foil 21 are adjusted to the negative electrode in the longitudinal direction of the negative electrode metal foil 31. It is conceivable to make it larger than the size of the tab 31b. In this case, the positive electrode tab 21b is more likely to wrinkle than the negative electrode tab 31b. Based on this, the wrinkles of the positive electrode tab 21b may be suppressed by forming the groove 27 only in the positive electrode tab 21b.

○ The shape of the penetrating portion penetrating the positive electrode exposed portion 25 or the negative electrode exposed portion 35 may be appropriately changed.
For example, as shown in FIG. 8, the penetrating portion is a U-shaped groove 41 that opens on the side opposite to the positive electrode coating portion 23 or the negative electrode coating portion 33 in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. There may be. The U-shaped groove 41 has a pair of side surface portions 41a extending along the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31, and a bottom surface portion 41b connecting the side surface portions 41a to each other. The bottom surface portion 41b is a curved surface that is recessed from the tip end side of the positive electrode tab 21b or the negative electrode tab 31b toward the positive electrode coating portion 23 side or the negative electrode coating portion 33 side in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. Is. In this case, it is possible to further prevent the U-shaped groove 41 from extending toward the positive electrode coating portion 23 or the negative electrode coating portion 33. The bottom surface portion 41b may be a flat surface extending along the longitudinal direction of the positive electrode metal foil 21 or the negative electrode metal foil 31.

For example, as shown in FIG. 9, the penetrating portion 42 is formed in the slit 42a extending in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31 and the positive electrode coating portion 23 side or the negative electrode coating portion 33 side in the slit 42a. It may have a shape having a circular hole portion 42b continuous with the positioned end portion. That is, the inner peripheral surface that partitions the circular hole portion 42b is the positive electrode coating portion 23 side or the negative electrode coating portion from the tip end side of the positive electrode tab 21b or the negative electrode tab 31b in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. It is a curved surface that is recessed toward the portion 33 side. Therefore, it is possible to further prevent the penetrating portion 42 from extending toward the positive electrode coating portion 23 side or the negative electrode coating portion 33 side.

Although not shown, the penetrating portion penetrates the positive electrode exposed portion 25 or the negative electrode exposed portion 35, and is connected to the positive electrode coating portion 23 or the negative electrode coating portion 33 in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. May be a V-shaped groove that opens on the opposite side.

○ The lengths of the grooves 27 and 37 may be appropriately changed as long as the wrinkles of the positive electrode exposed portion 25 or the negative electrode exposed portion 35 can be suppressed.
○ The penetrating portion is not limited to a groove shape, and may be a through hole.

For example, as shown in FIG. 10, the penetrating portion may be a track-shaped through hole 43. Specifically, the through hole 43 is formed by connecting a pair of straight portions 43a extending along the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31 and the straight portions 43a to the length of the positive electrode metal foil 21 or the negative electrode metal foil 31. It has a pair of arcs 43b connected in the direction. In this case, the through hole 43 is formed by punching out the positive electrode tab 21b or the negative electrode tab 31b in which the reinforcing layers 28 and 38 are formed. That is, when the positive electrode tab 21b or the negative electrode tab 31b is punched out to form the through hole 43, the reinforcing layers 28 and 38 are also punched out.

The shape of the through hole is not limited to the track shape, and may be appropriately changed, for example, a round hole or an ellipse.
When the penetrating portion is the groove 27, 37, the positive electrode tab 21b or the negative electrode tab 31b is divided and separated in the portion where the groove 27, 37 is formed. On the other hand, by making the through portion the through hole 43, it is possible to prevent the positive electrode tab 21b or the negative electrode tab 31b from coming apart. Therefore, the ease of handling of the positive electrode tab 21b or the negative electrode tab 31b is not impaired.

○ The material of the reinforcing layer 28 is not limited to resin, and may be other insulating material such as ceramic.
The reinforcing layer 28 may be present on only one side of the portion constituting the positive electrode exposed portion 25 or the negative electrode exposed portion 35 of the positive electrode metal foil 21 or the negative electrode metal foil 31.

○ The reinforcing layers 28 and 38 are between the inner ends 27a and 37a of the grooves 27 and 37 and the positive electrode active material layer 22 or the negative electrode active material layer 32 in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. If it is located in, the shapes of the reinforcing layers 28 and 38 may be changed as appropriate.

○ The reinforcing layers 28 and 38 are between the inner ends 27a and 37a of the grooves 27 and 37 and the positive electrode active material layer 22 or the negative electrode active material layer 32 in the lateral direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. If it is located in, the formation range of the reinforcing layers 28 and 38 may be appropriately changed.

The reinforcing layers 28 and 38 may be formed on the entire portion of the positive electrode metal foil 21 or the negative electrode metal foil 31 that constitutes the positive electrode exposed portion 25 or the negative electrode exposed portion 35, or may be formed on the positive electrode band-shaped portion 26 or the negative electrode strip-shaped portion 26. 36 may be formed so as not to overlap the grooves 27 and 37.

○ If wrinkles in the positive electrode exposed portion 25 or the negative electrode exposed portion 35 can be suppressed, the number of penetrating portions formed in one positive electrode tab 21b or negative electrode tab 31b may be appropriately changed.
When one positive electrode tab 21b or negative electrode tab 31b has a plurality of penetrating portions, the types of the penetrating portions may be different. For example, the positive electrode tab 21b or the negative electrode tab 31b has, for example, one through hole and two grooves arranged so as to sandwich the through hole in the longitudinal direction of the positive electrode metal foil 21 or the negative electrode metal foil 31. May be good.

○ If the wrinkles of the positive electrode exposed portion 25 or the negative electrode exposed portion 35 can be suppressed, the formation position of the penetrating portion in the positive electrode exposed portion 25 or the negative electrode exposed portion 35 may be appropriately changed. For example, the grooves 27 and 37 may extend to the positive electrode band-shaped portion 26 or the negative electrode strip-shaped portion 36. Further, for example, the grooves 27 and 37 may be formed only in the positive electrode band-shaped portion 26 or the negative electrode strip-shaped portion 36.

○ The positive electrode band-shaped portion 26 may be omitted. In this case, the positive electrode exposed portion 25 is composed of the positive electrode tab 21b. Further, the negative electrode band-shaped portion 36 may be omitted. In this case, the negative electrode exposed portion 35 is composed of the negative electrode tab 31b.

The electrode assembly 12 may be housed in the case 11 so that the winding shaft L coincides with the direction in which the pair of short side walls 13d face each other. In this case, for example, by omitting the positive electrode tab 21b and the negative electrode tab 31b, the positive electrode exposed portion 25 may be composed of the positive electrode band-shaped portion 26, and the negative electrode exposed portion 35 may be composed of the negative electrode strip-shaped portion 36. The positive electrode conductive member 17a is joined to the positive electrode strip-shaped portion 26, and the negative electrode conductive member 18a is joined to the negative electrode strip-shaped portion 36.

○ The first coating process and the second coating process may be performed at the same time.
○ The active material mixture 220 may be dried immediately after the first coating step, and the reinforcing layer material 280 may be dried immediately after the second coating step. That is, the step of drying the active material mixture 220 and the step of drying the reinforcing layer material 280 may be separate steps.

○ The cutting step and the groove forming step may be performed at the same time.
◯ One electrode sheet precursor 200a may be formed in the lateral direction of the electrode material 200.

○ In the pressing step, the electrode sheet precursor 200a may be pressed in the lateral direction of the positive electrode metal foil 21. In this case, the penetrating portion is preferably formed so as to extend along the longitudinal direction of the positive electrode metal foil 21.

○ The cutting step and the groove forming step may be performed after the pressing process is performed. In this case, in the pressing step, wrinkles may occur in the positive electrode exposed portion 25 or the negative electrode exposed portion 35, but the grooves 27 and 37 are formed in the positive electrode exposed portion 25 or the negative electrode exposed portion 35 by the subsequent groove forming step. This will eliminate the wrinkles.

○ The cutting method of the electrode material 200 is not limited to punching with a press die. For example, the electrode material 200 may be cut by a laser.
○ The method of forming the grooves 27 and 37 is not limited to punching with a press die. For example, the grooves 27, 37 may be formed by a laser.

○ The positive electrode active material layer 22 may be present over the entire longitudinal direction of the positive electrode metal foil 21. That is, the positive electrode sheet 20 may have the positive electrode coating portion 23 over the entire longitudinal direction of the positive electrode metal foil 21. In this case, in the first coating step, the active material mixture 220 is continuously coated on both sides of the metal foil material 210 in the longitudinal direction of the metal foil material 210.

Further, the negative electrode active material layer 32 may be present over the entire longitudinal direction of the negative electrode metal foil 31. That is, the negative electrode electrode sheet 30 may have the negative electrode coating portion 33 over the entire longitudinal direction of the negative electrode metal foil 31. In this case, in the first coating step, the active material mixture 220 is continuously coated on both sides of the metal foil material 210 in the longitudinal direction of the metal foil material 210.

○ A plurality of positive electrode electrodes may be formed by cutting the positive electrode sheet 20 at a plurality of locations in the longitudinal direction. Further, a plurality of negative electrode electrodes may be formed by cutting the negative electrode electrode sheet 30 at a plurality of locations in the longitudinal direction. The electrode assembly 12 may be a laminated electrode assembly in which a plurality of positive electrode electrodes and a plurality of negative electrode electrodes are alternately laminated via a separator.

The electrode assembly 12 may be an electrode assembly in which the positive electrode sheet 20 and the negative electrode sheet 30 are zigzag-folded via the separator 40.
○ In the positive electrode electrode sheet 20, the positive electrode coating portions 23 are present at a plurality of locations in the lateral direction of the positive electrode metal foil 21, and the positive electrode exposed portions 25 are located in the positive electrode coating portion 23 in the lateral direction of the positive electrode metal foil 21. It may exist in between. Similarly, in the negative electrode electrode sheet 30, the negative electrode coating portions 33 are present at a plurality of locations in the lateral direction of the negative electrode metal foil 31, and the negative electrode exposed portions 35 are the negative electrode coating portions in the lateral direction of the negative electrode metal foil 31. It may exist between 33.

○ In the positive electrode sheet 20, the positive electrode active material layer 22 may be present on one side of the positive electrode metal foil 21. Similarly, in the negative electrode electrode sheet 30, the negative electrode active material layer 32 may be present on one side of the negative electrode metal foil 31. However, the positive electrode active material layer 22 and the negative electrode active material layer 32 are opposed to each other via the separator 40.

○ The width of the positive electrode active material layer 22 in the longitudinal direction of the positive electrode metal foil 21 does not have to be the same for all the positive electrode active material layers 22. Further, the width of the negative electrode active material layer 32 in the longitudinal direction of the negative electrode metal foil 31 does not have to be the same for all the negative electrode active material layers 32.

○ The width of the negative electrode active material layer 32 in the longitudinal direction of the negative electrode metal foil 31 may be the same as the width of the positive electrode active material layer 22 in the longitudinal direction of the positive electrode metal foil 21, or is smaller than the width of the positive electrode active material layer 22. May be good.

○ The specific structures of the positive electrode terminal structure 17 and the negative electrode terminal structure 18 may be appropriately changed as long as electricity can be exchanged with the electrode assembly 12.
○ The pressure release valve 14a may be omitted.

○ When the pressure release valve 14a is arranged on the lid 14, the pressure release valve 14a is arranged at a position overlapping the positive electrode conductive member 17a and the negative electrode conductive member 18a if the function of the pressure release valve 14a is not impaired. May be good.

○ The number and arrangement of the pressure release valves 14a may be changed as follows, for example.
The secondary battery 10 may include two pressure release valves 14a. In this case, one pressure release valve 14a is located on one end side of the lid 14 in the longitudinal direction, and the other pressure release valve 14a is located on the other end side of the lid 14 in the longitudinal direction. One pressure release valve 14a faces the first uncoated laminated portion 12b, and the other pressure release valve 14a faces the second uncoated laminated portion 12c.

By the way, the amount of deformation of the case 11 when the internal pressure of the case 11 rises is smaller at the end portion of the lid 14 in the longitudinal direction than at the central portion. Therefore, by arranging the pressure release valves 14a at both ends in the longitudinal direction of the lid 14 having a small amount of deformation, the function of the pressure release valve 14a can be satisfactorily exhibited.

○ The arrangement of the pressure release valve 14a may be changed as follows, for example.
The pressure release valve 14a may be arranged at the center of the bottom wall 13b of the case body 13. In this case, when the pressure release valve 14a is activated, the electrolytic solution in the case 11 can be quickly flowed out of the case 11 from the pressure release valve 14a located on the bottom wall 13b.

○ The number and arrangement of the pressure release valves 14a may be changed as follows, for example.
The secondary battery 10 may include two pressure release valves 14a. In this case, one pressure release valve 14a is arranged on one short side wall 13d of the case body 13, and the other pressure release valve 14a is arranged on the other short side wall 13d of the case body 13. Further, each pressure release valve 14a is arranged near the bottom wall 13b in each short side wall 13d. In this case, when the pressure release valve 14a is activated, the electrolytic solution in the case 11 can be quickly discharged to the outside of the case 11 from the pressure release valve 14a located on each short side wall 13d.

○ The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, it is sufficient that ions move between the active material for the negative electrode and the active material for the negative electrode and charge is transferred.

○ The power storage device can also be applied to a power storage device other than a secondary battery, such as a capacitor.

20 ... Positive electrode electrode sheet as an electrode sheet, 21 ... Positive electrode metal foil as a metal foil, 22 ... Positive electrode active material layer as an active material layer, 23 ... Positive electrode coated part as a coated part, 25 ... As an exposed part Positive electrode exposed portion, 27 ... Groove as a through portion, 27a ... Inner end portion, 28 ... Reinforcing layer, 30 ... Negative electrode sheet as an electrode sheet, 31 ... Negative electrode metal foil as a metal foil, 32 ... As an active material layer Negative electrode active material layer, 33 ... Negative electrode coated portion as a coated portion, 35 ... Negative electrode exposed portion as an exposed portion, 37 ... Groove as a penetrating portion, 37a ... Inner end portion, 38 ... Reinforced layer.

Claims (4)

An electrode having a coated portion in which the metal foil and the active material layer are present and an exposed portion in which the active material layer is not present and the metal foil is exposed in the lateral direction of the long sheet-shaped metal foil. It ’s a sheet,
A penetrating portion that penetrates the exposed portion and
A reinforcing layer existing on at least one side of the exposed portion and
Have,
The penetrating portion has an inner end portion at an end portion located on the active material layer side in the lateral direction of the metal foil.
The electrode sheet is characterized in that the reinforcing layer is located between the inner end portion and the coated portion in the lateral direction of the metal foil. The electrode sheet according to claim 1, wherein the penetrating portion is a groove that opens on the side opposite to the coated portion in the lateral direction of the metal foil. The electrode sheet according to claim 1, wherein the penetrating portion is a hole. The electrode sheet according to any one of claims 1 to 3, wherein the inner end portion has a curved shape that is recessed toward the coated portion side in the lateral direction of the metal foil.