JP2021026910A - Electrical storage device - Google Patents

Abstract

To provide an electrical storage device by which the winding state of a wound electrode body can be maintained readily.SOLUTION: A wound electrode body 30 has: a pair of flat faces 33; a coated laminate part 31 where a plurality of positive electrode coated parts 43 and a plurality of negative electrode coated parts 53 are laminated; and an uncoated laminate part 32 where a plurality of positive electrode uncoated parts 44 and a plurality of negative electrode uncoated parts 54 are laminated. The coated laminate part 31 has the flat faces 33 formed on both sides in a lamination direction X. The uncoated laminate part 32 is arranged so that the coated laminate part 31 is sandwiched in a widthwise direction Z. A wound termination part 55 which is located in an outermost layer of the wound electrode body 30, and which makes an end of winding of a negative electrode 50 is formed by the negative electrode coated part 53. The winding termination part 55 and a second uncoated laminate part 32b are secured by a tape material 80 stuck along a longitudinal direction.SELECTED DRAWING: Figure 2

Description

The present invention relates to a power storage device.

Conventionally, vehicles such as EVs (Electric Vehicles) and PHVs (Plug in Hybrid Vehicles) have been equipped with lithium-ion secondary batteries, nickel-hydrogen secondary batteries, etc. as power storage devices for storing power supplied to electric motors and the like. .. The secondary battery includes an electrode assembly, an electrolytic solution, and a case for accommodating the electrode assembly and the electrolytic solution. As the electrode assembly, for example, a laminated electrode assembly in which a plurality of sheet-shaped positive electrode electrodes and a plurality of sheet-shaped negative electrode electrodes are alternately laminated, or a long sheet-shaped positive electrode and a long sheet-shaped electrode assembly. A wound electrode body, which is a wound type electrode assembly in which a negative electrode is laminated and wound, is known.

For example, Patent Document 1 discloses a wound electrode body. The wound electrode body is configured by being wound with a separator interposed between a long sheet-shaped positive electrode and a long sheet-shaped negative electrode. The wound electrode body has a flat shape. The wound electrode body has a pair of flat surfaces. The winding end portion of the separator of the wound electrode body is fixed to the outer surface of the wound electrode body with a tape material. The tape material is arranged at a position deviated from the pair of flat surfaces of the wound electrode body.

Japanese Unexamined Patent Publication No. 2008-7008

By the way, if the tape material is peeled off, the wound state of the wound electrode body may be loosened. As a result, the reaction between the sheet-shaped positive electrode current collector and the sheet-shaped negative electrode current collector may become non-uniform, and the life may be shortened.

The present invention has been made by paying attention to the problems existing in such a conventional technique, and an object of the present invention is to provide a power storage device that can easily maintain a wound state of a wound electrode body.

The power storage device that solves the above problems has a flat shape that is formed by winding a long sheet-shaped positive electrode and a long sheet-shaped negative electrode with a separator interposed therebetween. A power storage device including an electrode body, wherein the positive electrode and the negative electrode are made of metal and have a long sheet-like current collector and a plurality of active materials formed on at least one surface of the current collector. A layer, a plurality of coated portions having the active material layer on the current collector, and a plurality of uncoated parts in which the active material layer does not exist on the current collector and the current collector is exposed. The coated portion and the uncoated portion are provided alternately along the longitudinal direction of the positive electrode and the negative electrode, and the wound electrode body has a pair of flat surfaces. A coated laminated portion in which a plurality of the coated portions are laminated and an uncoated laminated portion in which the plurality of uncoated portions are laminated, and the direction in which the winding shaft extends is defined as the axial direction. When the direction in which the plurality of coated portions are laminated is the stacking direction and the direction orthogonal to the axial direction and the stacking direction is the width direction, the coated laminated portions are flat on both sides of the stacking direction. Is formed, and the uncoated laminated portion is arranged so as to sandwich the coated laminated portion in the width direction, is located in the outermost layer of the wound electrode body, and is either the positive electrode or the negative electrode. The winding end portion, which is the end of one of the windings, is composed of the coated portion, and the winding end portion and the uncoated laminated portion are fixed by a tape material attached along the longitudinal direction. Has been done.

According to this, the surface of the uncoated laminated portion to which the tape material is attached is a metal surface. Therefore, the tape material is easy to stick and hard to peel off. Further, since the winding end portion to which the tape material is attached is arranged on the first flat surface, the tape material is easily attached and is not easily peeled off. Therefore, it is easy to maintain the wound state of the wound electrode body.

In the above power storage device, both ends of the tape material may be attached to each of the pair of flat surfaces.
According to this, since the tape material is attached to each of the pair of flat surfaces, the tape material is more difficult to peel off. Therefore, it becomes easier to maintain the wound state of the wound electrode body.

According to the present invention, it is easy to maintain the wound state of the wound electrode body.

An exploded perspective view of the first embodiment of the power storage device. Top view of the wound electrode body of the first embodiment. (A) is a schematic view showing the configuration of the negative electrode, and (b) is a schematic view showing the configuration of the positive electrode. The perspective view which showed the structure of the positive electrode and the negative electrode. Side view of the wound electrode body. The top view which showed the structure of the tape material in 2nd Embodiment of a power storage device. The side view which showed the arrangement of the tape material in 2nd Embodiment. The side view which showed the arrangement of the tape material in the modification example of a power storage device. An exploded perspective view of a modified example. (A) and (b) are partial perspective views showing the arrangement of the pressure release valve in the modified example. (A) and (b) are partial perspective views showing the arrangement of the pressure release valve in the modified example.

<First Embodiment>
Hereinafter, a first embodiment in which the power storage device is embodied in a secondary battery will be described with reference to FIGS. 1 to 5.

As shown in FIG. 1, the secondary battery 10 as a power storage device includes a rectangular parallelepiped case 20, a flat wound electrode body 30 housed in the case 20, and an electrolytic solution (not shown) housed in the case 20. And have. The case 20 is made of a metal such as aluminum. Further, the secondary battery 10 of the present embodiment is a lithium ion secondary battery.

The case 20 has a bottomed square tubular case body 21 and a lid 22 that closes the opening 21c of the case body 21. The case body 21 has a square plate-shaped bottom wall 21a and a side wall 21b erected from the outer edge of the bottom wall 21a. The wound electrode body 30 is housed in the space surrounded by the bottom wall 21a and the side wall 21b in the case body 21. The side wall 21b of the case body 21 forms an opening 21c of the case body 21.

As shown in FIG. 2, the wound electrode body 30 is configured by winding with a separator 60 interposed between the long sheet-shaped positive electrode 40 and the long sheet-shaped negative electrode 50. ing. The positive electrode 40 and the negative electrode 50 are wound around the winding shaft O as the winding center. The positive electrode 40 and the negative electrode 50 are wound along the winding direction C centered on the winding axis O shown in the clockwise direction in FIG. The winding electrode body 30 of the present embodiment has a vertical winding type in which the winding shaft O is arranged so as to intersect the bottom wall 21a of the case body 21.

As shown in FIG. 3B, the positive electrode electrode 40 has a positive electrode current collector 41 as a current collector and a positive electrode active material layer 42 as a plurality of active material layers. The positive electrode current collector 41 is an aluminum foil. The positive electrode current collector 41 has a long sheet-shaped positive electrode main body 41a and a plurality of positive electrode tabs 41b protruding from one edge along the longitudinal direction of the positive electrode main body 41a. The longitudinal direction of the positive electrode main body 41a is the longitudinal direction of the positive electrode 40, and the lateral direction of the positive electrode main body 41a is the lateral direction of the positive electrode 40.

As shown in FIG. 2, the positive electrode active material layer 42 is formed on both sides of the positive electrode main body 41a. The plurality of positive electrode active material layers 42 existing on both sides of the positive electrode main body 41a are arranged at intervals in the longitudinal direction of the positive electrode main body 41a. Here, since the longitudinal direction of the positive electrode 40 and the winding direction C of the positive electrode 40 coincide with each other, the plurality of positive electrode active material layers 42 existing on both sides of the positive electrode main body 41a are along the winding direction C. They are arranged at intervals. The shape of the positive electrode active material layer 42 is the same in all the positive electrode active material layers 42, and is rectangular in the present embodiment.

As shown in FIG. 3B, the longitudinal direction of each positive electrode active material layer 42 coincides with the longitudinal direction of the positive electrode main body 41a, and the lateral direction of each positive electrode active material layer 42 is the short of the positive electrode main body 41a. It matches the hand direction. The coating width W1 in the longitudinal direction of the positive electrode active material layer 42 is the same in all the positive electrode active material layers 42. Further, the dimensions of the positive electrode active material layer 42 in the lateral direction are the same in all the positive electrode active material layers 42. The dimensions of the positive electrode active material layer 42 in the lateral direction are the same as the dimensions of the positive electrode main body 41a of the positive electrode current collector 41 in the lateral direction.

As shown in FIG. 2, the positive electrode electrode 40 has a positive electrode coating portion 43 as a plurality of coating portions in which the positive electrode active material layer 42 exists on the positive electrode current collector 41 and a positive electrode activity on the positive electrode current collector 41. The material layer 42 does not exist, and the positive electrode current collector 41 has a plurality of uncoated portions 44 which are exposed. The positive electrode coated portion 43 and the positive electrode uncoated portion 44 are alternately provided along the longitudinal direction of the positive electrode electrode 40.

As shown in FIG. 3B, the width W12 of the positive electrode uncoated portion 44 in the longitudinal direction of the positive electrode electrode 40 differs for each positive electrode uncoated portion 44. Specifically, the width W12 of each positive electrode uncoated portion 44 is as small as the positive electrode uncoated portion 44 located on the first end 40a side in the longitudinal direction of the positive electrode 40, and the second end 40b in the longitudinal direction of the positive electrode 40 It is as large as the positive electrode uncoated portion 44 located on the side. That is, the width W12 of the positive electrode uncoated portion 44 gradually increases from the first end 40a to the second end 40b of the positive electrode electrode 40.

Each positive electrode tab 41b is a portion where the positive electrode active material layer 42 does not exist and the positive electrode current collector 41 is exposed. The shape of the positive electrode tab 41b is the same for all the positive electrode tabs 41b, and is rectangular in this embodiment. Each positive electrode tab 41b protrudes from one edge of a portion of the positive electrode main body 41a that constitutes the positive electrode coating portion 43. That is, each positive electrode tab 41b is arranged at a position corresponding to each positive electrode coating portion 43 in the longitudinal direction of the positive electrode main body portion 41a. Further, in each positive electrode tab 41b, a positive electrode tab 41b located closer to one end in the longitudinal direction of the positive electrode active material layer 42 and a positive electrode tab 41b located closer to the other end in the longitudinal direction of the positive electrode active material layer 42 are positive electrode main bodies. They are arranged so as to exist alternately in the longitudinal direction of 41a.

As shown in FIG. 3A, the negative electrode electrode 50 has a negative electrode current collector 51 as a current collector and a negative electrode active material layer 52 as a plurality of active material layers. The negative electrode current collector 51 is a copper foil. The negative electrode current collector 51 has a long sheet-shaped negative electrode main body 51a, and a plurality of negative electrode tabs 51b protruding from one edge along the longitudinal direction of the negative electrode main body 51a. The longitudinal direction of the negative electrode body 51a is the longitudinal direction of the negative electrode 50, and the lateral direction of the negative electrode body 51a is the lateral direction of the negative electrode 50.

As shown in FIG. 2, the negative electrode active material layer 52 is formed on both surfaces of the negative electrode main body 51a. The plurality of negative electrode active material layers 52 existing on both sides of the negative electrode main body 51a are arranged at intervals in the longitudinal direction of the negative electrode main body 51a. Here, since the longitudinal direction of the negative electrode 50 and the winding direction C of the negative electrode 50 coincide with each other, the plurality of negative electrode active material layers 52 existing on both sides of the negative electrode main body 51a are along the winding direction C. They are arranged at intervals. The shape of the negative electrode active material layer 52 is the same in all the negative electrode active material layers 52, and is rectangular in the present embodiment.

As shown in FIG. 3A, the longitudinal direction of each negative electrode active material layer 52 coincides with the longitudinal direction of the negative electrode main body 51a, and the lateral direction of each negative electrode active material layer 52 is the short of the negative electrode main body 51a. It matches the hand direction. The coating width W2 in the longitudinal direction of the negative electrode active material layer 52 is the same in all the negative electrode active material layers 52. Further, the dimensions of the negative electrode active material layer 52 in the lateral direction are the same in all the negative electrode active material layers 52. The coating width W1 of the negative electrode active material layer 52 is larger than the coating width W2 of the positive electrode active material layer 42. Further, the dimensions of the negative electrode active material layer 52 in the lateral direction are the same as the dimensions of the negative electrode main body 51a of the negative electrode current collector 51 in the lateral direction.

As shown in FIG. 2, the negative electrode electrode 50 has a negative electrode coating portion 53 as a plurality of coating portions in which the negative electrode active material layer 52 exists on the negative electrode current collector 51 and a negative electrode activity on the negative electrode current collector 51. The material layer 52 does not exist, and the negative electrode current collector 51 has a plurality of uncoated portions 54 that are exposed. The negative electrode coated portion 53 and the negative electrode uncoated portion 54 are alternately provided along the longitudinal direction of the negative electrode electrode 50.

As shown in FIG. 3A, the width W22 of the negative electrode uncoated portion 54 in the longitudinal direction of the negative electrode electrode 50 differs for each negative electrode uncoated portion 54. Specifically, the width W22 of each positive electrode uncoated portion 44 is as small as the negative electrode uncoated portion 54 located on the first end 40a side in the longitudinal direction of the negative electrode electrode 50, and the second end 40b in the longitudinal direction of the negative electrode electrode 50. It is as large as the negative electrode uncoated portion 54 located in. That is, the width W22 of the negative electrode uncoated portion 54 gradually increases from the first end 40a to the second end 40b of the negative electrode electrode 50.

Each negative electrode tab 51b is a portion where the negative electrode active material layer 52 does not exist and the negative electrode current collector 51 is exposed. The shape of the negative electrode tab 51b is the same for all the negative electrode tabs 51b, and is rectangular in this embodiment. Each negative electrode tab 51b protrudes from one edge of a portion of the negative electrode main body 51a that constitutes the negative electrode coating portion 53. That is, each negative electrode tab 51b is arranged at a position corresponding to each negative electrode coating portion 53 in the longitudinal direction of the negative electrode main body portion 51a. Further, in each negative electrode tab 51b, a negative electrode tab 51b located closer to one end in the longitudinal direction of the negative electrode active material layer 52 and a negative electrode tab 51b located closer to the other end in the longitudinal direction of the negative electrode active material layer 52 are negative electrode main bodies. They are arranged so as to exist alternately in the longitudinal direction of 51a.

As shown in FIG. 2, the wound electrode body 30 includes a coated laminated portion 31 in which a plurality of positive electrode coated portions 43 and a plurality of negative electrode coated portions 53 are laminated via a separator 60, and a plurality of uncoated positive electrodes. The work portion 44 and the plurality of negative electrode uncoated portions 54 have an uncoated laminated portion 32 laminated via a separator 60. The direction in which the plurality of positive electrode coating portions 43 and the plurality of negative electrode coating portions 53 are laminated is defined as the stacking direction X, the extending direction of the winding axis O is defined as the axial direction Y, and the axial direction Y and the stacking direction X are orthogonal to each other. Assuming that the direction is the width direction Z, the uncoated laminated portion 32 is arranged so as to sandwich the coated laminated portion 31 in the width direction Z. The uncoated laminated portion 32 of the present embodiment is curved in an arc shape. In the coating lamination portion 31, the positive electrode coating portion 43 and the negative electrode coating portion 53 are alternately laminated via the separator 60 in the lamination direction X. Further, the wound electrode body 30 has a pair of flat surfaces 33 on both sides in the stacking direction X, and the flat surfaces 33 are formed by the coated laminated portion 31. As described above, the width W12 of the positive electrode uncoated portion 44 gradually increases from the first end 40a to the second end 40b of the positive electrode 40, and the width W12 from the first end 50a of the negative electrode 50 is increased. The width W22 of the negative electrode uncoated portion 54 gradually increases toward the two ends 50b. Therefore, when the wound electrode body 30 is viewed in the axial direction Y, the length of the plurality of positive electrode uncoated portions 44 and the plurality of negative electrode uncoated portions 54 along the winding direction C is the wound electrode body 30. The distance from the winding axis O becomes longer.

In this embodiment, two separators 60 are used. The separator 60 is a porous film through which lithium ions involved in electrical conductivity can pass. The two separators 60 are arranged so as to cover both sides of the positive electrode 40. Therefore, in the coated laminated portion 31, the two separators 60 are arranged between the positive electrode active material layer 42 of the positive electrode 40 and the negative electrode active material layer 52 of the negative electrode 50. Further, in the uncoated laminated portion 32, the two separators 60 are arranged between the positive electrode uncoated portion 44 of the positive electrode 40 and the negative electrode uncoated portion 54 of the negative electrode electrode 50. In the present embodiment, the outermost layer of the wound electrode body 30 is composed of the negative electrode 50. Therefore, the separator 60 is not located in the outermost layer of the wound electrode body 30, but is located inside the wound electrode body 30.

The wound electrode body 30 is formed into a flat shape by crushing and pulling the wound body of the positive electrode 40, the negative electrode 50, and the two separators 60 in the stacking direction X. Therefore, the positive electrode active material layer 42 and the negative electrode active material layer 52 in the coated laminated portion 31 of the wound electrode body 30 are maintained in close contact with the separator 60. In the present embodiment, the uncoated laminated portion 32 is curved in an arc shape, but when the wound electrode body 30 is pulled up as described above, the uncoated laminated portion 32 may be deformed. Therefore, the uncoated laminated portion 32 is not limited to being curved in an arc shape, and may have any shape as long as it is arranged so as to sandwich the coated laminated portion 31 in the width direction Z. ..

As shown in FIG. 1, the wound electrode body 30 has a positive electrode tab group 36 and a negative electrode tab group 37. The positive electrode tab group 36 is located at the coated laminated portion 31 of the positive electrode current collector 41 when the wound electrode body 30 is formed by winding the positive electrode electrode 40, the negative electrode electrode 50, and the two separators 60. It is configured by gathering a plurality of positive electrode tabs 41b to be gathered in the stacking direction X. The negative electrode tab group 37 is located at the coated laminated portion 31 of the negative electrode current collector 51 when the wound electrode body 30 is formed by winding the positive electrode electrode 40, the negative electrode electrode 50, and the two separators 60. It is configured by gathering a plurality of negative electrode tabs 51b in the stacking direction X.

The secondary battery 10 includes a wound electrode body 30 and a positive electrode terminal structure 15 and a negative electrode terminal structure 16 for transmitting and receiving electricity. The positive electrode terminal structure 15 has a plate-shaped positive electrode conductive member 15a connected to the positive electrode tab group 36, and a rod-shaped positive electrode terminal 15b protruding from the positive electrode conductive member 15a. The negative electrode terminal structure 16 has a plate-shaped negative electrode conductive member 16a connected to the negative electrode tab group 37, and a rod-shaped negative electrode terminal 16b protruding from the negative electrode conductive member 16a. The positive electrode terminal 15b and the negative electrode terminal 16b each penetrate the lid 22 and project to the outside of the case 20. An insulating ring 19 for insulating the lid 22 and the positive electrode terminal 15b is attached to the positive electrode terminal 15b. An insulating ring 19 for insulating the lid 22 and the negative electrode terminal 16b is attached to the negative electrode terminal 16b.

As shown in FIG. 2, a protective layer 70 is provided on the plurality of positive electrode uncoated portions 44 and the plurality of negative electrode uncoated portions 54 constituting the uncoated laminated portion 32 of the wound electrode body 30. .. The protective layer 70 is made of an insulating material containing alumina as a main component. Alumina is an insulating metal oxide. The protective layer 70 is a so-called heat resistance layer (HRL). The protective layer 70 is provided on the outer surface of the positive electrode uncoated portion 44 in the innermost layer of the uncoated laminated portion 32. The protective layer 70 is provided on the outer surface of the negative electrode uncoated portion 54 in the innermost layer of the uncoated laminated portion 32. The protective layer 70 is provided on the inner surface of the negative electrode uncoated portion 54 in the outermost layer of the uncoated laminated portion 32. The protective layer 70 is provided on both sides of the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54 in the middle layer located between the innermost layer and the outermost layer of the uncoated laminated portion 32. That is, in the uncoated laminated portion 32 of the wound electrode body 30, either the positive electrode uncoated portion 44 of the positive electrode 40 and the negative electrode uncoated portion 54 of the negative electrode 50 facing each other via the separator 60 , A protective layer 70 is provided. When the wound electrode body 30 is viewed in the axial direction Y, the protective layer 70 is provided over the entire area of the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54.

The configuration of the protective layer 70 will be described in more detail with reference to FIG. The protective layer 70 shown in FIG. 4 is shown by extracting a part of the portion located in the middle layer of the wound electrode body 30, but even if it is the innermost layer and the outermost layer of the wound electrode body 30. It has a similar configuration.

As shown in FIG. 4, the thickness of the protective layer 70 is thinner than that of the positive electrode active material layer 42 and the negative electrode active material layer 52. The protective layer 70 is provided in the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54 over the entire length of the positive electrode current collector 41 and the negative electrode current collector 51 in the lateral direction. That is, when the positive electrode 40 and the negative electrode 50 are wound along the winding direction C to form the wound electrode body 30, the protective layer 70 is provided over the entire length in the axial direction Y shown in FIG. There is. In the protective layer 70, the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54 are formed after the positive electrode active material layer 42 and the negative electrode active material layer 52 are formed on the positive electrode current collector 41 and the negative electrode current collector 51. It is formed by applying a slurry containing alumina as a main component.

As shown in FIG. 2, the outermost layer of the wound electrode body 30 is composed of the negative electrode 50. In the winding electrode body 30, the winding end portion 55, which is the end of winding of the negative electrode 50, is composed of the negative electrode coating portion 53. The winding end portion 55 is arranged on the first flat surface 33a, which is one of the pair of flat surfaces 33 of the winding electrode body 30. Further, the other of the pair of flat surfaces 33 is referred to as a second flat surface 33b. Of the uncoated laminated portions 32, the uncoated laminated portion 32 continuous with the first flat surface 33a is designated as the first uncoated laminated portion 32a, and is located on the side opposite to the first uncoated laminated portion 32a in the width direction Z. The located uncoated laminated portion 32 is referred to as a second uncoated laminated portion 32b. The winding end portion 55 of the winding electrode body 30 and the second uncoated laminated portion 32b are fixed by a long tape material 80 attached along the longitudinal direction of the negative electrode electrode 50. Since the winding end portion 55 is composed of the negative electrode coating portion 53, one end portion 81 in the longitudinal direction of the tape material 80 is attached to the negative electrode active material layer 52 constituting the first flat surface 33a. There is. The other end 82 in the longitudinal direction of the tape material 80 is attached to the metal surface of the negative electrode current collector 51 of the negative electrode 50 forming the surface of the second uncoated laminated portion 32b.

As shown in FIG. 5, two tape materials 80 are provided so as to sandwich the central portion of the wound electrode body 30 in the axial direction Y of the wound electrode body 30.
The operation and effect of this embodiment will be described.

(1-1) The surface of the uncoated laminated portion 32 to which the tape material 80 is attached is a metal surface. Therefore, the tape material 80 is easy to be attached and is not easily peeled off. Further, since the winding end portion 55 to which the tape material 80 is attached is arranged on the first flat surface 33a, the tape material 80 is easily attached and is not easily peeled off. Therefore, it is easy to maintain the wound state of the wound electrode body 30.

(1-2) Even if the separator 60 located in the uncoated laminated portion 32 is torn, the protective layer 70 is interposed between the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54 of the negative electrode electrode 50. The protective layer 70 can prevent the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54 from coming into contact with each other. Therefore, a short circuit in the uncoated laminated portion 32 of the wound electrode body 30 can be suppressed.

(1-3) The protective layer 70 is coated with a slurry containing alumina as a main component after the positive electrode active material layer 42 and the negative electrode active material layer 52 are formed on the positive electrode current collector 41 and the negative electrode current collector 51. It is formed by doing. Therefore, when the protective layer 70 is formed on the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54, the slurry coating of the slurry forming the protective layer 70 by the adjacent positive electrode coated portion 43 or the adjacent negative electrode coated portion 53 is applied. Work positioning is possible. Therefore, the misalignment of the protective layer 70 can be suppressed.

(1-4) The coating width W1 of the positive electrode active material layer 42 of the positive electrode coating portion 43 is the same in all the positive electrode active material layers 42, and the coating width of the negative electrode active material layer 52 of the negative electrode coating portion 53. W2 is the same in all the negative electrode active material layers 52. Therefore, when the wound body of the positive electrode electrode 40, the negative electrode electrode 50, and the two separators 60 is pulled up so as to have a flat shape, the positive electrode active material in the coated laminated portion 31 of the wound electrode body 30. Since the surface pressure acts uniformly on the layer 42 and the negative electrode active material layer 52, uneven reaction on the electrical conductivity of the wound electrode body 30 can be suppressed.

<Second Embodiment>
Hereinafter, a second embodiment in which the power storage device is embodied in a secondary battery will be described with reference to FIGS. 6 and 7. The same components as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, both ends of the tape material 80 are attached to each of the pair of flat surfaces 33. One end 81 of the tape material 80 is attached to the winding end 55. The other end 82 of the tape material 80 is attached to the second flat surface 33b. The tape material 80 is attached to the second flat surface 33b while fixing the winding end portion 55 and the second uncoated laminated portion 32b along the longitudinal direction of the negative electrode electrode 50.

As shown in FIG. 7, two tape materials 80 are provided so as to sandwich the central portion of the wound electrode body 30 in the axial direction Y of the wound electrode body 30.
The operation and effect of this embodiment will be described.

(2-1) Since the tape material 80 is attached to the second flat surface 33b, the tape material 80 is more difficult to peel off. Therefore, it becomes easier to maintain the wound state of the wound electrode body 30.
Each of the above embodiments can be modified and implemented as follows. Each of the above embodiments and the following modified examples can be implemented in combination with each other within a technically consistent range.

〇 As shown in FIG. 8, one tape material 80 may be provided so as to include the central portion of the wound electrode body 30 in the axial direction Y of the winding direction C. Note that FIG. 8 embodies the case where the other end 82 of the tape material 80 is attached to the second uncoated laminated portion 32b, but the tape material 80 is used as in the second embodiment. The end portion 82 may be changed so as to be attached to the second flat surface 33b of the wound electrode body 30.

〇 As shown in FIG. 9, a laminated fixing tape material 100 for fixing the coated laminated portion 31 in the laminated direction X may be attached to the wound electrode body 30. Two laminated fixing tape materials 100 are used. The two laminated fixing tape materials 100 are arranged so as to sandwich the central portion of the wound electrode body 30 in the width direction Z. Both ends of the two laminated fixing tape materials 100 are located on the second flat surface 33b of the pair of flat surfaces 33. That is, the two laminated fixing tape materials 100 are attached so as to cover the upper surface and the lower surface of the wound electrode body 30 in the axial direction Y. A binding force is generated from the first flat surface 33a and the second flat surface 33b by the two laminated fixing tape materials 100 so as to maintain the laminated state of the coated laminated portion 31. Therefore, it becomes easier to maintain the wound state of the wound electrode body 30. Further, although the description is omitted in each of the above embodiments, the lid 22 of the case 20 is provided with a liquid injection port 14 for injecting the electrolytic solution into the case 20. The two laminated fixing tape materials 100 are arranged at positions that do not overlap the liquid injection port 14 in the axial direction Y. Therefore, the electrolytic solution injected from the liquid injection port 14 can be impregnated into the wound electrode body 30 without being interfered with by the two laminated fixing tape materials 100. In the secondary battery 10, after the electrolytic solution is injected from the injection port 14, the injection port 14 is closed by the injection plug 17. The liquid injection port 14 may be provided in the case body 21 instead of the lid 22. Even with this change, the liquid injection port 14 is arranged at a position that does not overlap the two laminated fixing tape materials 100 in the axial direction Y.

〇 Further, as shown in FIG. 9, although the description is omitted in each of the above embodiments, the lid 22 of the case 20 is provided with the pressure release valve 18. The pressure release valve 18 is cleaved when the pressure inside the case 20 reaches an opening pressure, which is a predetermined pressure, so that the pressure inside the case 20 does not rise too much when gas is generated inside the case 20. Therefore, since the inside and outside of the case 20 are communicated with each other, the pressure inside the case 20 is released to the outside of the case 20.

If the pressure release valve 18 is left in an open state, foreign matter may enter the inside of the case 20 from the released pressure release valve 18. Since the foreign matter may short-circuit the wound electrode body 30, it is preferable that the flammable electrolytic solution inside the case 20 is discharged to the outside of the case 20 when the pressure release valve 18 is opened. Therefore, the arrangement of the pressure release valve 18 may be changed as follows.

As shown in FIGS. 10A and 10B, the pressure release valve 18 may be provided on the side wall 21b of the case body 21 corresponding to the width direction Z of the wound electrode body 30. However, since the electrolytic solution collects on the bottom wall 21a of the case body 21, the pressure release valve 18 is arranged closer to the bottom wall 21a of the case body 21 than the central portion m in the height direction of the case body 21. Good. By making such a change, the electrolytic solution inside the case 20 can be discharged to the outside of the case 20 at the same time when the pressure inside the case 20 reaches the opening pressure which is a predetermined pressure. The pressure release valve 18 may be provided on the side wall 21b of the case body 21 corresponding to the stacking direction X of the wound electrode body 30. That is, the pressure release valve 18 may be arranged on the side wall 21b of the case body 21 closer to the bottom wall 21a of the case body 21 than to the central portion m.

〇 Further, as shown in FIGS. 11A and 11B, the pressure release valve 18 may be provided on the bottom wall 21a of the case body 21. The pressure release valve 18 may be changed so as to be provided at both ends of the bottom wall 21a in the width direction Z of the wound electrode body 30. Even with this change, when the pressure inside the case 20 reaches the opening pressure, which is a predetermined pressure, the case 20 is cleaved, and at the same time, the electrolytic solution inside the case 20 can be discharged to the outside of the case 20.

〇 The arrangement of the protective layer 70 may be changed as follows. The protective layer 70 is omitted in the innermost layer of the uncoated laminated portion 32. In the outermost layer of the uncoated laminated portion 32, the protective layer 70 is provided on the inner surface of the negative electrode uncoated portion 54. In the middle layer of the uncoated laminated portion 32, the protective layer 70 is provided on the inner surfaces of the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54.

〇 Further, the arrangement of the protective layer 70 may be changed as follows. The protective layer 70 is provided on the outer surface of the positive electrode uncoated portion 44 in the innermost layer of the uncoated laminated portion 32. The protective layer 70 is provided on the outer surface of the negative electrode uncoated portion 54 in the innermost layer of the uncoated laminated portion 32. In the outermost layer of the uncoated laminated portion 32, the protective layer 70 is provided on the outer surface of the negative electrode uncoated portion 54. In the middle layer of the uncoated laminated portion 32, it is provided on the outer surface of the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54. That is, in the uncoated laminated portion 32 of the wound electrode body 30, the protective layer 70 may be provided on either one of the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54 facing each other via the separator 60. ..

〇 The protective layer 70 may be provided over the entire length of the positive electrode 40 and the negative electrode 50 in the longitudinal direction. Even if it is changed in this way, the alumina constituting the protective layer 70 has a characteristic that lithium ions related to electrical conductivity can pass through. Therefore, even if the protective layer 70 is changed to be provided over the entire length of the positive electrode 40 and the negative electrode 50 in the longitudinal direction, the protective layer 70 exchanges ions between the positive electrode active material layer 42 and the negative electrode active material layer 52. The protective layer 70 can be provided without impairing the function of the secondary battery 10.

〇 Further, the protective layer 70 may be made of a resin as an insulating material. However, the resin does not have the property of passing lithium ions that are electrically conductive. Therefore, when the protective layer 70 is made of resin, the protective layer 70 is arranged only in the positive electrode uncoated portion 44 and the negative electrode uncoated portion 54.

〇 The protective layer 70 is formed by applying a slurry containing alumina as a main component after the positive electrode active material layer 42 and the negative electrode active material layer 52 are formed on the positive electrode current collector 41 and the negative electrode current collector 51. It was, but it is not limited to this. For example, the positive electrode current collector 41 and the negative electrode current collector 51 are coated with a slurry containing alumina as a main component to form a protective layer 70, and then the positive electrode active material layer 42 and the negative electrode active material layer 52 are formed. It may be changed as follows. When changing in this way, the coating thickness of the slurry containing alumina as a main component is made as thin as possible. By reducing the coating thickness of the slurry, the positioning accuracy of the protective layer 70 can be improved without the protective layer 70 being diffused more than necessary. By improving the positioning accuracy of the protective layer 70, the positioning accuracy of the positive electrode active material layer 42 and the negative electrode active material layer 52 can also be improved. If it is possible to thin the slurry constituting the protective layer 70, a highly accurate coating technique such as general gravure coating can be used.

〇 In the wound electrode body 30, the protective layer 70 provided on the uncoated laminated portion 32 may be omitted.
〇 The coating width W1 of the positive electrode active material layer 42 in the plurality of positive electrode coating portions 43 is the same in all the positive electrode active material layers 42, and the coating width W2 of the negative electrode active material layer 52 in the plurality of negative electrode coating portions 53. Was the same in all the negative electrode active material layers 52, but is not limited to this. The coating widths W1 and W2 may be appropriately changed as long as the reaction between the positive electrode active material layer 42 and the negative electrode active material layer 52 related to the electrical conductivity of the wound electrode body 30 is not hindered.

〇 In the positive electrode 40, the positive electrode active material layer 42 may exist on only one side of the positive electrode current collector 41. In the negative electrode 50, the negative electrode active material layer 52 may exist on only one side of the negative electrode current collector 51. However, in the coated laminated portion 31 of the wound electrode body 30, the positive electrode active material layer 42 and the negative electrode active material layer 52 are opposed to each other via the separator 60.

〇 The dimensions of the positive electrode active material layer 42 in the lateral direction are the same as the dimensions of the positive electrode main body 41a of the positive electrode current collector 41 in the lateral direction, and the dimensions of the negative electrode active material layer 52 in the lateral direction are the negative electrode collection. The dimensions of the negative electrode main body 51a of the electric body 51 in the lateral direction were the same, but the dimensions were not limited to this. For example, the short-side dimension of the positive electrode active material layer 42 is shorter than the short-side dimension of the positive electrode main body 41a, and the short-side dimension of the negative electrode active material layer 52 is the short-side dimension of the negative electrode main body 51a. It may be shorter than the dimensions. That is, an uncoated portion where the positive electrode active material layer 42 is not coated is formed on one edge of the positive electrode main body 41a on which the positive electrode tab 41b protrudes in the longitudinal direction, and the negative electrode main body 51b protrudes. The one edge portion along the longitudinal direction of the portion 51a may be formed with an uncoated portion in which the negative electrode active material layer 52 is not coated.

〇 The positions of the positive electrode 40 and the negative electrode 50 may be exchanged. In this case, the outermost layer of the wound electrode body 30 is composed of the positive electrode 40. In the winding electrode body 30, the winding end portion 55, which is the end of winding of the positive electrode 40, is composed of the positive electrode coating portion 43 of the positive electrode 40. Since the winding end portion 55 is composed of the positive electrode coating portion 43, one end portion 81 of the tape material 80 in the winding direction C is attached to the positive electrode active material layer 42 constituting the first flat surface 33a. Be done. The other end 82 in the winding direction C of the tape material 80 is attached to the metal surface of the positive electrode current collector 41 of the positive electrode 40 forming the surface of the second uncoated laminated portion 32b.

〇 The winding electrode body 30 has a vertical winding type in which the winding shaft O is arranged so as to intersect the bottom wall 21a of the case body 21, but is not limited to this. The winding electrode body 30 may have a lateral winding type in which the winding shaft O is arranged so as to intersect the side wall 21b of the case body 21.

〇 When the winding electrode body 30 has a horizontal winding type, it is preferable to position the winding end portion 55 of the winding electrode body 30 on the opening 21c side of the case body 21. It is generally known that the secondary battery 10 is cooled from the bottom wall 21a side of the case body 21. For example, when the winding end portion 55 of the winding electrode body 30 is located on the bottom wall 21a side of the case body 21, the tape material 80 is interposed between the winding electrode body 30 and the bottom wall 21a of the case body 21. This may interfere with the cooling of the secondary battery 10. Therefore, the cooling effect of the secondary battery 10 can be improved by locating the winding end portion 55 of the winding electrode body 30 on the opening 21c side of the case body 21.

〇 When the wound electrode body 30 is changed to the horizontal winding type, it is preferable that the configuration of the positive electrode tab group 36 and the negative electrode tab group 37 of the wound electrode body 30 is appropriately changed.
〇 The configurations of the positive electrode terminal structure 15 and the negative electrode terminal structure 16 may be appropriately changed as long as electricity can be exchanged with the wound electrode body 30.

〇 The secondary battery 10 is not limited to the lithium ion secondary battery, and may be another secondary battery. In short, it is sufficient that the ions move between the active material for the positive electrode and the active material for the negative electrode and transfer charges.

〇 The power storage device can be applied to a power storage device other than the secondary battery 10 such as a capacitor.

10 ... secondary battery, 30 ... wound electrode body, 31 ... coated laminated part, 32 ... uncoated laminated part, 33 ... pair of flat surfaces, 33a ... first flat surface, 33b ... second flat surface, 40 ... Positive electrode, 41 ... Positive electrode current collector, 42 ... Positive electrode active material layer, 43 ... Positive electrode coated part, 44 ... Positive electrode uncoated part, 50 ... Negative electrode, 51 ... Negative electrode current collector, 52 ... Negative electrode active material Layer, 53 ... Negative electrode coated part, 54 ... Negative electrode uncoated part, 55 ... Winding end part, 60 ... Separator, 70 ... Protective layer, 80 ... Tape material, C ... Winding direction, O ... Winding shaft, X ... stacking direction, Y ... axial direction, Z ... width direction.

Claims (2)

A power storage device including a flat-shaped wound electrode body formed by winding with a separator interposed between a long sheet-shaped positive electrode and a long sheet-shaped negative electrode. ,
The positive electrode and the negative electrode
A current collector made of metal and forming a long sheet,
A plurality of active material layers formed on at least one side of the current collector,
A plurality of coated parts in which the active material layer exists on the current collector, and
It has a plurality of uncoated portions where the active material layer does not exist on the current collector and the current collector is exposed.
The coated portion and the uncoated portion are alternately provided along the longitudinal direction of the positive electrode and the negative electrode.
The wound electrode body is
A pair of flat surfaces and
A coated laminated portion in which a plurality of the coated portions are laminated,
It has an uncoated laminated portion in which a plurality of the uncoated portions are laminated, and
Assuming that the extending direction of the winding shaft is the axial direction, the direction in which the plurality of coated portions are laminated is the stacking direction, and the direction orthogonal to the axial direction and the stacking direction is the width direction.
The coated laminated portion forms the flat surfaces on both sides in the laminating direction.
The uncoated laminated portion is arranged so as to sandwich the coated laminated portion in the width direction.
The winding end portion, which is located in the outermost layer of the wound electrode body and is the end of winding of either the positive electrode or the negative electrode, is composed of the coating portion.
A power storage device characterized in that the winding end portion and the uncoated laminated portion are fixed by a tape material attached along the longitudinal direction. The power storage device according to claim 1, wherein both ends of the tape material are attached to each of the pair of flat surfaces.