JP2021057275A - Electrochemical cell - Google Patents

Abstract

To provide an electrochemical cell that can adapt to exterior packaging bodies having various shapes, secure capacity, and suppress deterioration of reliability.SOLUTION: A battery includes a negative electrode body 50 and a positive electrode body 60 that are wound flatly while overlapping with each other. The negative electrode body 50 has a plurality of negative electrode connecting portions 52 each of which connects a pair of adjacent negative electrode bodies 51 in an expanded state, has a negative active material placed on the surface thereof, and is folded back so that the pair of negative electrode bodies 51 overlap each other. The positive electrode body 60 has a plurality of positive electrode connecting portions 62 each of which connects a pair of adjacent positive electrode main bodies 61 in an expanded state, has a positive electrode active material placed on the surface thereof, and faces each of the plurality of negative electrode connecting portions 52. When i represents at least one integer of 3 or more and not more than the number of the plurality of negative electrode connecting portions 52, the minimum negative electrode width of an i-th negative electrode connecting portion is smaller than the minimum negative electrode width of a (i-2)-th negative electrode connecting portion. The minimum positive electrode width of a (i-1)-th positive electrode connecting portion is smaller than the minimum negative electrode width of the i-th negative electrode connecting portion and the minimum negative electrode width of the (i-2)-th negative electrode connecting portion.SELECTED DRAWING: Figure 10

Description

The present invention relates to an electrochemical cell.

Conventionally, electrochemical cells such as lithium ion secondary batteries and electrochemical capacitors have been widely used as a power source for small devices such as smartphones, wearable devices, and hearing aids.
In such an electrochemical cell, it is necessary to increase the area of the electrodes facing each other in the electrochemical cell from the viewpoint of increasing the battery capacity and the charging current and the discharging current. The structure of the electrochemical cell is such that a pair of band-shaped electrodes are wound so as to face each other via a band-shaped separator to form a wound body, the wound body is housed in an outer body, and an electrolytic solution is placed on the electrode and the electrolytic solution. A structure in which the separator is impregnated is known. When the strip-shaped electrode has a certain width, the wound body is formed in a columnar shape. Therefore, depending on the shape of the exterior body, it is necessary to deform the wound body wound in a columnar shape into a flat shape.

However, when the wound body is deformed into a flat shape, the shape of the wound body after deformation is limited to a relatively simple shape such as a rectangular parallelepiped shape. Therefore, depending on the shape of the exterior body, it is difficult to arrange the electrode body on the exterior body at a high density.

Patent Document 1 below discloses a configuration in which the wound body is formed in a non-rectangular shape in a plan view. In Patent Document 1, the positive electrode plate and the negative electrode plate are each formed in a band shape in which a plurality of laminated surfaces are connected by a connecting piece, and the laminated surface of the positive electrode plate and the laminated surface of the negative electrode plate are alternately laminated via a separator. As described above, a battery in which a positive electrode plate and a negative electrode plate are bent by a connecting piece and wound into a flat shape to form a group of electrode plates is disclosed. According to this battery, when the shape of the laminated surface of each of the positive electrode plate and the negative electrode plate is appropriately set, the outer body has a shape other than the rectangular parallelepiped as compared with the configuration in which the wound body is formed in a rectangular parallelepiped shape. The electrode plates can be arranged at high density on the exterior body.

International Publication No. 02/13305

However, when the strip-shaped electrode is bent by the connecting piece and wound into a flat shape, the plan view shape of the wound body may be a shape in which the connecting piece protrudes. For example, in the configuration disclosed in Patent Document 1, a plurality of connecting pieces of the positive electrode plate extend with the same width, and a plurality of connecting pieces of the negative electrode plate extend with the same width, so that they are connected in a plan view. The pieces protrude from the laminated surface so as to be angular. For this reason, a gap is likely to be formed around the protruding portion formed by the connecting piece in the wound body inside the exterior body. Therefore, it is difficult to arrange the flat wound body without a gap on the non-rectangular outer body.

Further, when the wound body is flatly wound in a non-rectangular shape, the band-shaped electrodes may have a complicated shape in the deployed state, but even in this case, a short circuit between the pair of electrodes must be suppressed. .. Therefore, in the prior art, in an electrochemical cell having a non-rectangular outer body, electrodes are arranged at a high density to secure a capacity, and short circuits between the electrodes are suppressed to suppress a decrease in reliability. There is room for improvement in terms of doing so.

Therefore, the present invention provides an electrochemical cell that is compatible with exterior bodies having various shapes, secures capacity, and suppresses deterioration of reliability.

The electrochemical cell of the present invention includes a negative electrode body and a positive electrode body that are overlapped with each other and wound flatly, and the negative electrode body is a plurality of negative electrode bodies arranged in a row in the first direction in a deployed state. A plurality of negative electrode connecting portions in which a pair of negative electrode bodies adjacent to each other in a deployed state are connected, a negative electrode active material is arranged on the surface thereof, and the pair of negative electrode bodies are folded back so as to overlap each other. The positive electrode bodies are arranged side by side in a second direction in the unfolded state, and a plurality of positive electrode bodies overlapping the negative electrode bodies and a pair of positive electrode bodies adjacent to each other in the unfolded state among the plurality of positive electrode bodies. Is connected, a positive electrode active material is arranged on the surface, and a plurality of positive electrode connection portions facing the plurality of negative electrode connection portions are provided, N is a natural number, and N is set as a natural number on the innermost circumference of the plurality of negative electrode connection portions. The negative electrode connection portion located at the Nth position from the arranged negative electrode connection portion toward the outer peripheral side is defined as the Nth negative electrode connection portion, and the outer periphery from the positive electrode connection portion arranged on the innermost circumference of the plurality of positive electrode connection portions. The positive electrode connection portion located at the Nth position toward the side is defined as the Nth positive electrode connection portion, and the minimum width in the direction orthogonal to the first direction is defined as the negative electrode minimum width in each of the plurality of negative electrode connection portions. When the minimum width in the direction orthogonal to the second direction is defined as the positive electrode minimum width in each of the plurality of positive electrode connecting portions, the negative electrode body is a pair connected to the first negative electrode connecting portion among the plurality of negative electrode bodies. The negative electrode body is wound so as to sandwich the inner peripheral end portion of the positive electrode body, and the positive electrode body is formed by a pair of positive electrode bodies connected to the first positive electrode connecting portion of the plurality of positive electrode bodies. When i is 3 or more and at least one integer equal to or less than the number of the plurality of negative electrode connecting portions, the minimum width of the negative electrode of the i-th negative electrode connecting portion is the first. (I-2) The minimum width of the negative electrode of the negative electrode connection portion is smaller than the minimum width of the negative electrode, and the minimum width of the positive electrode of the (i-1) positive electrode connection portion is the minimum width of the negative electrode of the i-th negative electrode connection portion and the minimum width of the negative electrode (i-2). ) The negative electrode connection portion is smaller than the minimum width of the negative electrode.

According to this configuration, the negative electrode active material is arranged on the surface of the negative electrode connecting portion, and the positive electrode active material is arranged on the positive electrode connecting portion facing the negative electrode connecting portion. Discharge (charge / discharge in the case of a secondary battery) can also be performed at the negative electrode connection portion and the positive electrode connection portion. Therefore, the capacity of the electrochemical cell can be improved as compared with the configuration in which the active material is not arranged on the surfaces of the negative electrode connecting portion and the positive electrode connecting portion.
Further, in the above configuration, the negative electrode body is wound by folding back the negative electrode connecting portion so that a plurality of negative electrode bodies overlap each other. Therefore, the negative electrode connection portion located at an odd number from the first negative electrode connection portion toward the outer peripheral side in the deployed state is in a direction orthogonal to the winding axis direction with respect to the negative electrode main body when viewed from the direction in which the plurality of negative electrode main bodies are laminated. Placed on one side. Further, the negative electrode connecting portions located even-numbered from the first negative electrode connecting portion toward the outer peripheral side in the deployed state are in a direction orthogonal to the winding axis direction with respect to the negative electrode main body when viewed from the direction in which a plurality of negative electrode main bodies are laminated. Is placed on the other side of. According to the above configuration, with respect to the i-th negative electrode connection portion and the (i-2) negative electrode connection portion adjacent to each other in the wound state, the i-th negative electrode connection portion on the outer layer side when viewed from the direction in which a plurality of negative electrode bodies are laminated. The width of is narrower than the width of the (i-2) negative electrode connection portion on the inner layer side. As a result, the i-th negative electrode connecting portion and the (i-2) negative electrode connecting portion are arranged so as to be gradually narrowed as they are separated from the negative electrode main body when viewed from the direction in which the plurality of negative electrode main bodies are laminated. Therefore, the negative electrode body can be wound into a desired flat shape with small irregularities when viewed from the direction in which the plurality of negative electrode bodies are laminated, and the negative electrode body and the positive electrode body can be arranged without gaps in the exterior body. Therefore, it is possible to provide an electrochemical cell that can be used for exterior bodies having various shapes and has a sufficient capacity.
Further, in the above configuration, the (i-1) positive electrode connecting portion is arranged between the i-th negative electrode connecting portion and the (i-2) negative electrode connecting portion that are adjacent to each other in the wound state. According to the above configuration, the minimum positive electrode width of the (i-1) positive electrode connection portion is smaller than the minimum negative electrode width of the i-th negative electrode connection portion and the minimum negative electrode width of the (i-2) negative electrode connection portion. The entire first (i-1) positive electrode connection portion faces the main surface of each of the i-th negative electrode connection portion and the (i-2) negative electrode connection portion. As a result, it is possible to suppress the occurrence of electric field concentration at the outer edges of the i-th negative electrode connection portion and the (i-2) negative electrode connection portion, respectively, during charging. Since the negative electrode active material is arranged on the surfaces of the i-th negative electrode connecting portion and the (i-2) negative electrode connecting portion, the negative electrode active material absorbs the metal constituting the ion applied to the electrochemical cell. It is possible to suppress the precipitation of metal due to the concentration of the electric field. Therefore, it is possible to suppress a short circuit between the negative electrode body and the positive electrode body and improve the reliability of the electrochemical cell.

In the above electrochemical cell, assuming that j is 2 or more and all integers less than the number of the plurality of negative electrode connecting portions, the minimum width of the positive electrode of the j positive electrode connecting portion is the negative electrode of the (j + 1) negative electrode connecting portion. It may be smaller than the minimum width and the minimum width of the negative electrode of the (j-1) negative electrode connection portion.

According to this configuration, all of the positive electrode connection portions arranged between the pair of negative electrode connection portions in the wound state of the plurality of positive electrode connection portions face the main surface of the negative electrode connection portions. As a result, it is possible to suppress metal precipitation due to electric field concentration at the outer edges of all the negative electrode connection portions during charging. Therefore, it is possible to suppress a short circuit between the negative electrode body and the positive electrode body and improve the reliability of the electrochemical cell.

In the above electrochemical cell, where k is the number of the plurality of negative electrode connection portions, the minimum positive electrode width of the k-th positive electrode connection portion is smaller than the minimum negative electrode width of the (k-1) negative electrode connection portion. May be good.

According to this configuration, all of the positive electrode connection portions that overlap the negative electrode connection portion from the outer layer side in the wound state of the plurality of positive electrode connection portions face the main surface of the negative electrode connection portion. As a result, it is possible to more reliably suppress metal precipitation due to electric field concentration at the outer edges of all the negative electrode connection portions during charging. Therefore, it is possible to suppress a short circuit between the negative electrode body and the positive electrode body and improve the reliability of the electrochemical cell.

In the above electrochemical cell, the minimum width of the positive electrode of the first positive electrode connection portion may be smaller than the minimum width of the negative electrode of the second negative electrode connection portion.

According to this configuration, all of the positive electrode connection portions that overlap the negative electrode connection portion from the inner layer side in the wound state of the plurality of positive electrode connection portions face the main surface of the negative electrode connection portion. As a result, it is possible to more reliably suppress metal precipitation due to electric field concentration at the outer edges of all the negative electrode connection portions during charging. Therefore, it is possible to suppress a short circuit between the negative electrode body and the positive electrode body and improve the reliability of the electrochemical cell.

In the above electrochemical cell, the plurality of negative electrode connecting portions may be arranged inside the both end portions in the direction orthogonal to the first direction in the plurality of negative electrode bodies.

As described above, the plurality of negative electrode connection portions are arranged in a direction orthogonal to the winding axis direction with respect to the negative electrode body when viewed from the direction in which the plurality of negative electrode bodies are laminated. According to the above configuration, the plurality of negative electrode connecting portions are arranged inside the both ends of the plurality of negative electrode bodies in the direction orthogonal to the first direction, so that the plurality of negative electrode bodies can be viewed from the direction in which the plurality of negative electrode bodies are laminated. It is arranged so as to project from the negative electrode body in a direction orthogonal to the winding axis direction. Here, in the configuration in which the plurality of negative electrode connecting portions protrude from the negative electrode main body with a constant width, the joint portion between the negative electrode main body and the negative electrode connecting portion is formed in the outer shape of the negative electrode body when viewed from the direction in which the plurality of negative electrode main bodies are laminated. A recess is formed, and a gap is likely to be formed between the recess and the exterior body. Therefore, as described above, the i-th negative electrode connecting portion and the (i-2) negative electrode connecting portion are arranged so as to gradually narrow in width as they are separated from the negative electrode main body when viewed from the direction in which the plurality of negative electrode main bodies are laminated. By doing so, the above-mentioned recess can be filled by the negative electrode connection portion. Therefore, it is possible to obtain an electrochemical cell in which a gap is unlikely to be formed inside the exterior.

In the above electrochemical cell, the positive electrode active material may contain a lithium compound.

According to this configuration, lithium ions can be absorbed by the negative electrode active material of the negative electrode body. Therefore, it is possible to suppress the precipitation of needle-shaped lithium from the negative electrode body. Therefore, it is possible to suppress a short circuit between the negative electrode body and the positive electrode body and improve the reliability of the electrochemical cell.

According to the present invention, it is possible to provide an electrochemical cell that is compatible with exterior bodies having various shapes, secures capacity, and suppresses deterioration of reliability.

It is a perspective view of the battery of an embodiment. It is sectional drawing of the battery of embodiment. It is a top view of the electrode structure of an embodiment. FIG. 3 is a cross-sectional view taken along the line IV-IV of FIG. It is a development view before winding of the negative electrode body of an embodiment. It is a development view before winding of the positive electrode body of an embodiment. It is a figure which shows the negative electrode body of an embodiment, and the winding method of a positive electrode body. It is a top view of the negative electrode body and the positive electrode body, and is the figure which developed the electrode structure in the state which maintained the positional relationship between the 1st negative electrode body and the 2nd positive electrode body. It is a top view of the negative electrode body and the positive electrode body, and is the figure which developed the electrode structure in the state which maintained the positional relationship between the 2nd negative electrode body and the 1st positive electrode body. It is a top view which shows a part of each of a negative electrode body and a positive electrode body, and is the figure which developed the electrode structure in the state which maintained the positional relationship between the 9th negative electrode connection part and the 8th positive electrode connection part. It is a top view which shows a part of each of a negative electrode body and a positive electrode body, and is the figure which developed the electrode structure in the state which maintained the positional relationship between the 7th negative electrode connection part and the 8th positive electrode connection part. It is a top view which shows the negative electrode body accommodated in the accommodating part.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same reference numerals are given to configurations having the same or similar functions. Then, the duplicate description of those configurations may be omitted. Further, in the following description, as the electrochemical cell, a lithium ion secondary battery (hereinafter, simply referred to as “battery”), which is a kind of non-aqueous electrolyte secondary battery, will be described as an example.

FIG. 1 is a perspective view of the battery of the embodiment. FIG. 2 is a cross-sectional view of the battery of the embodiment.
As shown in FIGS. 1 and 2, the battery 1 is a so-called button-shaped battery having a circular shape in a plan view. The battery 1 includes an electrode structure 40 of a power generation element having a positive electrode active material and a negative electrode active material, an electrolytic solution (not shown) impregnated in the electrode structure 40, and an exterior body 10 accommodating the electrode structure 40. , Equipped with.

The exterior body 10 forms the outer shell of the battery 1. The exterior body 10 includes an accommodating portion 11 in which the electrode structure 40 is accommodated, and a sealing portion 12 bent along the outer circumference 11a of the accommodating portion 11. The sealing portion 12 is bent along the outer circumference 11a of the accommodating portion 11 by, for example, drawing.

Further, the exterior body 10 includes a first container 20 and a second container 30 that sandwich the electrode structure 40 in between. The first container 20 and the second container 30 are each formed of a laminated film. The laminated film includes a metal layer (metal foil), a resin fusion layer provided on the overlapping surface (inner side surface) and covering the metal layer, and a resin protective layer provided on the outer surface and covering the metal layer. And have. The metal layer is formed by using a metal material such as stainless steel or aluminum that blocks outside air and water vapor. The fused layer on the overlapping surface is formed by using, for example, a thermoplastic resin such as polyolefin polyethylene or polypropylene. The protective layer on the outer side surface is formed by using, for example, the above-mentioned polyolefin, polyester such as polyethylene terephthalate, nylon, or the like.

The diameter of the first container 20 is expanded from the circular first bottom wall portion 21, the first peripheral wall portion 22 extending in a tubular shape from the outer periphery of the first bottom wall portion 21, and the opening edge of the first peripheral wall portion 22. A first flange portion 23 extending in a tubular shape is provided. A first through hole 24 is formed in the first bottom wall portion 21. For example, the first through hole 24 is formed in the center of the first bottom wall portion 21.

A copper plate 26 is heat-sealed on the inner surface of the first bottom wall portion 21 via a first sealant ring 25. The first sealant ring 25 is a ring-shaped sealant film. The sealant film is formed by using a thermoplastic resin such as polyethylene or polypropylene which is a polyolefin.

The inner surface of the copper plate 26 is connected to a negative electrode lead 2 (see FIG. 3), which will be described later. A nickel plate 27 is welded to the center of the outer surface of the copper plate 26. The nickel plate 27 penetrates the first through hole 24 and is exposed to the outside, and functions as a negative electrode terminal of the battery 1. Further, instead of the copper plate 26, a nickel plate material can be used. In this case, the nickel plate 27 may not be provided.

The first peripheral wall portion 22 forms a part of the outer peripheral portion 11a of the accommodating portion 11. The first flange portion 23 protrudes outward in the radial direction from the opening edge of the first peripheral wall portion 22, and further extends to a side away from the first bottom wall portion 21 with a substantially constant diameter.

The diameter of the second container 30 is expanded from the circular second bottom wall portion 31, the second peripheral wall portion 32 extending in a tubular shape from the outer periphery of the second bottom wall portion 31, and the opening edge of the second peripheral wall portion 32. A second flange portion 33 extending in a tubular shape is provided.

The second bottom wall portion 31 is arranged on the side opposite to the first bottom wall portion 21 of the first container 20 with the electrode structure 40 interposed therebetween. The second bottom wall portion 31 is formed to have substantially the same diameter as the first bottom wall portion 21 of the first container 20. A second through hole 34 is formed in the second bottom wall portion 31. For example, the second through hole 34 is formed in the center of the second bottom wall portion 31.

A stainless steel plate 36 is heat-sealed on the inner surface of the second bottom wall portion 31 via a second sealant ring 35. The second sealant ring 35, like the first sealant ring 25, is made of a thermoplastic resin.

The inner surface of the stainless plate 36 is connected to a positive electrode lead 3 (see FIG. 3), which will be described later. A nickel plate 37 is welded to the center of the outer surface of the stainless plate 36. The nickel plate 37 penetrates the second through hole 34 and is exposed to the outside, and functions as a positive electrode terminal of the battery 1. For example, instead of the stainless steel plate 36, a plate material made of aluminum can be used.

The second peripheral wall portion 32 extends from the outer periphery of the second bottom wall portion 31 toward the first bottom wall portion 21 of the first container 20. The second peripheral wall portion 32 and the first peripheral wall portion 22 form an outer peripheral portion 11a of the accommodating portion 11. The second flange portion 33 protrudes outward in the radial direction from the opening edge of the second peripheral wall portion 32, and further extends toward the second bottom wall portion 31 along the second peripheral wall portion 32 with a substantially constant diameter. The second flange portion 33 is arranged so as to be spaced outside from the second peripheral wall portion 32.

The second peripheral wall portion 32 is arranged inside the first flange portion 23 and inside the second flange portion 33. Further, the second flange portion 33 is arranged inside the first flange portion 23. The fusion layer of the second flange portion 33 is heat-sealed to the fusion layer of the first flange portion 23.

The accommodating portion 11 accommodates the electrode structure 40 between the first container 20 and the second container 30. Specifically, the accommodating portion 11 is formed by the first bottom wall portion 21, the first peripheral wall portion 22, the second bottom wall portion 31, and the second peripheral wall portion 32, and is formed in a circular shape in a plan view. The sealing portion 12 is formed by overlapping the first container 20 and the second container 30 on the entire circumference around the accommodating portion 11 in a plan view. Specifically, the sealing portion 12 is formed by heat-sealing the fusion layer of the first flange portion 23 of the first container 20 and the fusion layer of the second flange portion 33 of the second container 30. It is formed. As a result, the first container 20 and the second container 30 are superposed to form the exterior body 10. The sealing portion 12 projects from the intermediate portion of the accommodating portion 11 in the overlapping direction of the first container 20 and the second container 30 of the exterior body 10.

FIG. 3 is a plan view of the electrode structure of the embodiment. FIG. 4 is a cross-sectional view taken along the line IV-IV of FIG.
As shown in FIGS. 3 and 4, the electrode structure 40 includes a sheet-shaped negative electrode body 50, a positive electrode body 60, and a separator 70. The electrode structure 40 is a laminated type electrode body that is folded so that the negative electrode body 50 and the positive electrode body 60 are alternately laminated. Specifically, the electrode structure 40 is formed by superimposing the negative electrode body 50 and the positive electrode body 60 via the separator 70 and winding them flat. The negative electrode body 50 and the positive electrode body 60 are wound around a predetermined winding axis O together with the separator 70. The separator 70 is arranged in the entire layer between the negative electrode body 50 and the positive electrode body 60, and insulates the negative electrode body 50 and the positive electrode body 60.

The negative electrode body 50 is a single sheet-like member including a negative electrode current collecting foil formed of a metal material and a negative electrode active material coated on the negative electrode current collecting foil. The negative electrode current collector foil is formed of, for example, a metal foil such as copper or stainless steel. The negative electrode active material is, for example, silicon oxide, graphite, hard carbon, lithium titanate, LiAl or the like.

The positive electrode body 60 is a single sheet-like member including a positive electrode current collecting foil formed of a metal material and a positive electrode active material coated on the positive electrode current collecting foil. The positive electrode current collector foil is formed of, for example, a metal foil such as aluminum or stainless steel. The positive electrode active material is a composite oxide containing lithium and a transition metal, such as lithium cobalt oxide, lithium titanate, and lithium manganate.

The separator 70 is a member having a property of passing lithium ions. The separator 70 is formed of, for example, a resin porous film made of polyolefin, a non-woven fabric made of glass, a non-woven fabric made of resin, a laminate of cellulose fibers, or the like.

The electrode structure 40 is formed in a non-rectangular shape in a plan view when viewed from the thickness direction of the electrode structure 40. Specifically, the electrode structure 40 corresponds to the shape of the sealed space in the accommodating portion 11 and is formed in a circular shape in a plan view. In the following description, the thickness direction of the electrode structure 40 is simply referred to as the thickness direction, the direction along the winding axis O is referred to as the axial direction, and the thickness direction and the direction orthogonal to the axial direction are the axial perpendicular directions. That is. The thickness direction coincides with the overlapping direction of the first container 20 and the second container 30 of the exterior body 10.

Here, the shape of the negative electrode body 50 in the deployed state of the electrode structure 40 will be described.
FIG. 5 is a developed view of the negative electrode body of the embodiment before winding.
As shown in FIG. 5, the negative electrode body 50 is formed in a band shape as a whole in the unfolded state before being wound. The negative electrode body 50 is a plurality of (9 in the illustrated example) negative electrode connecting portions that connect a plurality of (10 in the illustrated example) negative electrode bodies 51 arranged side by side in a row and a pair of adjacent negative electrode bodies 51. 52 and. The negative electrode body 51 is a portion of the electrode structure 40 that extends flat along a vertical plane in the stacking direction (see FIG. 4). The negative electrode connecting portion 52 is a portion that is folded back at the side portion of the electrode structure 40 so that the plurality of negative electrode main bodies 51 overlap each other (see FIG. 4). Each negative electrode body 51 includes one portion where the width of the negative electrode body 50 is maximized in a plan view. Each negative electrode connecting portion 52 includes one portion in which the width of the negative electrode body 50 is minimized in a plan view.

Hereinafter, the direction in which the plurality of negative electrode bodies 51 are lined up is referred to as the negative electrode longitudinal direction (first direction), and the direction orthogonal to the negative electrode longitudinal direction is referred to as the negative electrode lateral direction. Further, in the longitudinal direction of the negative electrode, the negative electrode body 51 side arranged on the outer peripheral side of the electrode structure 40 is opposed to the negative electrode body 51 arranged on the most winding center side of the electrode structure 40 among the plurality of negative electrode main bodies 51. It is defined as "outer circumference side", and the opposite direction is defined as "inner circumference side". Further, in the following description, the plurality of negative electrode main bodies 51 will be described with ordinal numbers in order from the innermost peripheral negative electrode main body 51 to the outer peripheral side. In other words, N is a natural number, and the negative electrode body located Nth from the innermost negative electrode body 51 toward the outer peripheral side is defined as the Nth negative electrode body. The same applies to the plurality of negative electrode connection portions 52. Further, the plurality of negative electrode connecting portions 52 are the first group 53 to which all the negative electrode connecting portions 52 located at odd numbers from the first negative electrode connecting portion 52A toward the outer peripheral side belong, and the outer peripheral side from the first negative electrode connecting portion 52A. A second group 54 to which all the negative electrode connecting portions 52 located at the even-numbered positions toward the above belong.

The negative electrode body 50 is formed line-symmetrically with the center line along the negative electrode connecting direction as the axis of symmetry in a plan view. The plurality of negative electrode bodies 51 are arranged so that their centers in the lateral direction of the negative electrode are located on the same straight line along the longitudinal direction of the negative electrode in the deployed state. Each negative electrode body 51 is formed in a shape in which both ends in the longitudinal direction of the negative electrode are cut out with respect to a circle having a predetermined diameter. The plurality of negative electrode connecting portions 52 are provided between a pair of negative electrode main bodies 51 adjacent to each other in the longitudinal direction of the negative electrode. Each negative electrode connecting portion 52 is arranged inside each of the pair of negative electrode main bodies 51 connected to the negative electrode connecting portion 52 with respect to both ends in the negative electrode lateral direction.

The negative electrode lead 2 is connected to the outer peripheral end of the negative electrode body 50. The negative electrode lead 2 is a portion connected to the copper plate 26 described above. The negative electrode lead 2 extends along the longitudinal direction of the negative electrode from the negative electrode main body 51 arranged on the outermost circumference. The negative electrode lead 2 is integrally formed of the same member as the negative electrode current collecting foil of the negative electrode body 50.

Here, in each negative electrode connection portion 52, the minimum width in the negative electrode lateral direction is defined as the negative electrode minimum width (see reference numeral W1 in FIG. 5). Of the negative electrode connecting portions 52 belonging to the first group 53, at least a part of the negative electrode connecting portions 52 is continuously in the negative electrode connecting direction so that the minimum width of the negative electrode gradually decreases from the inner peripheral side to the outer peripheral side in the deployed state. They are lined up. In the present embodiment, all the negative electrode connecting portions 52 belonging to the first group 53 are arranged in the negative electrode connecting direction so that the minimum width of the negative electrode gradually decreases from the inner peripheral side to the outer peripheral side in the deployed state. Of the negative electrode connecting portions 52 belonging to the second group 54, at least a part of the negative electrode connecting portions 52 are continuously in the negative electrode connecting direction so that the minimum width of the negative electrode gradually decreases from the inner peripheral side to the outer peripheral side in the deployed state. They are lined up. In the present embodiment, among the negative electrode connecting portions 52 belonging to the second group 54, the negative electrode connecting portions 52 other than the eighth negative electrode connecting portion 52H on the outermost circumference have a minimum negative electrode width from the inner peripheral side to the outer peripheral side in the expanded state. They are lined up in the negative electrode connection direction so that they become larger in sequence. Based on the above, assuming that i is 3 or more and at least one integer (i is 3 to 7, and 9 in this embodiment) equal to or less than the number of the plurality of negative electrode connection portions 52 (that is, 9), the i-th negative electrode connection portion 52 The minimum negative electrode width is smaller than the minimum negative electrode width of the (i-2) negative electrode connection portion 52.

Further, at least a part of the negative electrode connecting portions 52 among the plurality of negative electrode connecting portions 52 are continuously arranged in the negative electrode connecting direction so that the minimum width of the negative electrode gradually decreases from the inner peripheral side to the outer peripheral side in the deployed state. There is. In the present embodiment, the first negative electrode connecting portion 52A to the seventh negative electrode connecting portion 52G are arranged so that the minimum width of the negative electrode gradually decreases or becomes equal from the inner peripheral side to the outer peripheral side in the deployed state. That is, assuming that m is a plurality of consecutive integers of 2 or more (m is 2 to 7 in this embodiment), the minimum width of the negative electrode of the mth negative electrode connection portion 52 is the negative electrode of the (m-1) negative electrode connection portion 52. It is less than the minimum width. The minimum negative electrode widths of the 8th negative electrode connection portion 52H and the 9th negative electrode connection portion 52I are equal to each other and larger than the minimum negative electrode width of the 7th negative electrode connection portion 52G.

Next, the shape of the positive electrode body 60 in the deployed state of the electrode structure 40 will be described.
FIG. 6 is a developed view of the positive electrode body of the embodiment before winding.
As shown in FIG. 6, the positive electrode body 60 is formed in a band shape as a whole in the unfolded state before being wound. The positive electrode body 60 is a plurality of (10 in the illustrated example) positive electrode bodies 61 arranged side by side in a row and at least one (9 in the illustrated example) positive electrode connecting a pair of adjacent positive electrode bodies 61. It has a connecting portion 62 and. The positive electrode body 61 is a portion of the electrode structure 40 that extends flat along a vertical plane in the stacking direction (see FIG. 3). The positive electrode connecting portion 62 is a portion that is folded back at the side portion of the electrode structure 40 so that the plurality of positive electrode main bodies 61 overlap the negative electrode main body 51 (see FIG. 3). Each positive electrode body 61 includes one portion where the width of the positive electrode body 60 is maximized in a plan view. Each positive electrode connecting portion 62 includes one portion where the width of the positive electrode body 60 is minimized in a plan view.

Hereinafter, the direction in which the plurality of positive electrode main bodies 61 are lined up is referred to as the positive electrode longitudinal direction (second direction), and the direction orthogonal to the positive electrode longitudinal direction is referred to as the positive electrode lateral direction. Further, in the longitudinal direction of the positive electrode, the positive electrode body 61 side arranged on the outer peripheral side of the electrode structure 40 is defined as the positive electrode body 61 arranged on the most winding center side of the electrode structure among the plurality of positive electrode main bodies 61. It is defined as "outer circumference side", and the opposite direction is defined as "inner circumference side". Further, in the following, the plurality of positive electrode main bodies 61 and the plurality of positive electrode connecting portions 62 will be described with an ordinal number in the same manner as the negative electrode main body 51 and the negative electrode connecting portion 52.

The positive electrode body 60 is formed line-symmetrically with the center line along the positive electrode connecting direction as the axis of symmetry in a plan view. The plurality of positive electrode main bodies 61 are provided in the same number as the negative electrode main bodies 51. The plurality of positive electrode bodies 61 are arranged so that their centers in the lateral direction of the positive electrode are located on the same straight line along the longitudinal direction of the positive electrode in the deployed state. Each positive electrode body 61 is formed in a shape in which both ends in the longitudinal direction of the positive electrode are cut out with respect to a circle having a diameter smaller than that of the negative electrode body 51. As a result, the dimension of each positive electrode body 61 in the lateral direction of the positive electrode is smaller than the dimension of the negative electrode body 51 in the lateral direction of the negative electrode. The plurality of positive electrode connecting portions 62 are provided between a pair of positive electrode main bodies 61 adjacent to each other in the longitudinal direction of the positive electrode.

A positive electrode lead 3 is connected to the outer peripheral end of the positive electrode body 60. The positive electrode lead 3 is a portion connected to the stainless steel plate 36 described above. The positive electrode lead 3 extends from the positive electrode main body 61 arranged on the outermost circumference along the longitudinal direction of the positive electrode. The positive electrode lead 3 is integrally formed of the same member as the positive electrode current collecting foil of the positive electrode body 60.

Here, in each positive electrode connection portion 62, the minimum width in the lateral direction of the positive electrode is defined as the minimum width of the positive electrode (see reference numeral W2 in FIG. 6). Assuming that j is 2 or more and all integers less than the number of the plurality of negative electrode connecting portions 52 (that is, 9), the minimum positive electrode width of the j positive electrode connecting portion 62 is the minimum negative electrode width of the (j + 1) negative electrode connecting portion 52. And it is smaller than the minimum negative electrode width of the (j-1) negative electrode connecting portion 52. Therefore, when the above-mentioned integer i is used, the minimum positive electrode width of the (i-1) positive electrode connecting portion 62 is the minimum negative electrode width of the i-th negative electrode connecting portion 52 and the negative electrode of the (i-2) negative electrode connecting portion 52. It is smaller than the minimum width. The minimum positive electrode width of the first positive electrode connection portion 62A is smaller than the minimum negative electrode width of the second negative electrode connection portion 52B (see FIG. 5). Further, the minimum positive electrode width of the ninth positive electrode connection portion 62I is smaller than the minimum negative electrode width of the eighth negative electrode connection portion 52H (see FIG. 5).

Next, the winding structure of the negative electrode body 50 and the positive electrode body 60 will be described.
The negative electrode body 50 and the positive electrode body 60 are wound in a state in which the centers in the lateral direction in each deployed state are arranged so as to overlap each other. The negative electrode body 50 is wound by folding back each negative electrode connecting portion 52 while keeping each negative electrode body 51 flat. Each negative electrode connecting portion 52 is folded so that a pair of negative electrode main bodies 51 connected to the negative electrode connecting portion 52 overlap each other when viewed from the thickness direction. The positive electrode body 60 is wound by folding back each positive electrode connecting portion 62 while keeping each positive electrode body 61 flat. Each positive electrode connecting portion 62 is folded so that a pair of positive electrode main bodies 61 connected to the positive electrode connecting portion 62 overlap each other when viewed from the thickness direction. The plurality of negative electrode bodies 51 and the plurality of positive electrode bodies 61 are alternately laminated in the thickness direction. The plurality of negative electrode bodies 51 and the plurality of positive electrode bodies 61 are arranged so that their center points coincide with each other on the winding axis O in a plan view. Each of the plurality of negative electrode connecting portions 52 and the plurality of positive electrode connecting portions 62 is arranged at the end portion in the axial direction of the electrode structure 40.

FIG. 7 is a diagram showing a method of winding the negative electrode body and the positive electrode body of the embodiment. Note that the separator is omitted in FIG. 7 (the same applies to the following figures).
As shown in FIG. 7, first, the first negative electrode body 51A of the negative electrode body 50 and the first positive electrode body 61A of the positive electrode body 60 are overlapped with each other. At this time, a winding core may be interposed between the first negative electrode body 51A and the first positive electrode body 61A. Subsequently, the negative electrode body 50 and the positive electrode body 60 are wound around the first negative electrode body 51A and the first positive electrode body 61A.

Specifically, the negative electrode body 50 and the positive electrode body 60 are wound by the following procedure. The first negative electrode connection portion 52A of the negative electrode body 50 is folded back, and the second negative electrode body 51B is overlapped with the first positive electrode body 61A on the side opposite to the first negative electrode body 51A. At this time, the first negative electrode main body 51A and the second negative electrode main body 51B are arranged so that their center points overlap each other when viewed from the overlapping direction of the first negative electrode main body 51A and the first positive electrode main body 61A. Further, the first positive electrode connecting portion 62A of the positive electrode body 60 is folded back, and the second positive electrode main body 61B is overlapped with the first negative electrode main body 51A on the side opposite to the first positive electrode main body 61A. At this time, the first positive electrode main body 61A and the second positive electrode main body 61B are arranged so that their center points overlap each other when viewed from the overlapping direction of the first negative electrode main body 51A and the first positive electrode main body 61A. After that, the negative electrode connecting portions 52 are folded back so that the negative electrode main bodies 51 overlap each other, and the positive electrode connecting portions 62 are folded back so that the positive electrode main bodies 61 overlap each other. As a result, the negative electrode body 50 is wound so as to sandwich the first positive electrode body 61A by the first negative electrode body 51A and the second negative electrode body 51B. The positive electrode body 60 is wound by the first positive electrode body 61A and the second positive electrode body 61B so as to sandwich the first negative electrode body 51A. By folding back the negative electrode connecting portion 52 and the positive electrode connecting portion 62 in this order, the negative electrode body 50 and the positive electrode body 60 are wound.

Next, the positional relationship between the negative electrode body 50 and the positive electrode body 60 will be described.
As shown in FIG. 4, the plurality of positive electrode main bodies 61 face the negative electrode main body 51 via the separator 70. The tenth positive electrode body 61J faces one negative electrode body 51 via the separator 70. Of the plurality of positive electrode main bodies 61, the positive electrode main bodies 61 other than the tenth positive electrode main body 61J face the pair of negative electrode main bodies 51 via the separator 70. For example, the first positive electrode body 61A faces the first negative electrode body 51A and the second negative electrode body 51B via the separator 70.

The plurality of positive electrode connecting portions 62 face the negative electrode connecting portion 52 via the separator 70. The first positive electrode connection portion 62A and the ninth positive electrode connection portion 62I face one negative electrode connection portion 52 via the separator 70. Of the plurality of positive electrode connection portions 62, the Nth positive electrode connection portion 62 excluding the first positive electrode connection portion 62A and the ninth positive electrode connection portion 62I is connected to the (N + 1) negative electrode connection portion 52 and the (N-1) th (N-1) th negative electrode connection portion 62 via the separator 70. ) Facing the negative electrode connection portion 52.

FIG. 8 is a plan view of the negative electrode body and the positive electrode body, and is a view in which the electrode structure is developed while maintaining the positional relationship between the first negative electrode body and the second positive electrode body. FIG. 9 is a plan view of the negative electrode body and the positive electrode body, and is a view in which the electrode structure is developed while maintaining the positional relationship between the second negative electrode body and the first positive electrode body.
As shown in FIGS. 8 and 9, the dimension of each positive electrode body 61 in the lateral direction of the positive electrode is smaller than the dimension of the negative electrode body 51 in the lateral direction of the negative electrode, so that the entire first positive electrode body 61A faces each other. 2 The negative electrode body 51B is located inside the outer edge when viewed from the thickness direction. Further, the entire second positive electrode body 61B is located inside the outer edge of the facing first negative electrode body 51A when viewed from the thickness direction. As described above, the entire positive electrode body 61 is located inside the outer edge of one or a pair of the negative electrode bodies 51 facing each other when viewed from the thickness direction, and faces the main surface of the negative electrode body 51 via the separator 70. doing.

FIG. 10 is a plan view showing a part of each of the negative electrode body and the positive electrode body, and is a view in which the electrode structure is developed while maintaining the positional relationship between the ninth negative electrode connection portion and the eighth positive electrode connection portion. .. FIG. 11 is a plan view showing a part of each of the negative electrode body and the positive electrode body, and is a view in which the electrode structure is developed while maintaining the positional relationship between the 7th negative electrode connection portion and the 8th positive electrode connection portion. ..
As shown in FIG. 10, since the minimum positive electrode width of the eighth positive electrode connection portion 62H is smaller than the minimum negative electrode width of the ninth negative electrode connection portion 52I, the entire eighth positive electrode connection portion 62H is formed by the ninth negative electrode connection portion 52I. It is located inside the outer edge of the ninth negative electrode connecting portion 52I when viewed from the direction in which the eighth positive electrode connecting portion 62H and the eighth positive electrode connecting portion 62H overlap. Further, as shown in FIG. 11, the minimum positive electrode width of the 8th positive electrode connection portion 62H is smaller than the minimum negative electrode width of the 7th negative electrode connection portion 52G, so that the entire 8th positive electrode connection portion 62H is connected to the 7th negative electrode. The portion 52G and the eighth positive electrode connecting portion 62H are located inside the outer edge of the seventh negative electrode connecting portion 52G when viewed from the overlapping direction.

As described above, when the above-mentioned integer j is used, the minimum width of the positive electrode of the j-th positive electrode connection portion 62 is smaller than the minimum width of the negative electrode of the (j + 1) negative electrode connection portion 52, so that the entire j-th positive electrode connection portion 62 is formed. , The j + 1th negative electrode connection portion 52 and the j positive electrode connection portion 62 are located inside the outer edge of the (j + 1) negative electrode connection portion 52 when viewed from the overlapping direction. Further, since the minimum positive electrode width of the j positive electrode connection portion 62 is smaller than the minimum negative electrode width of the (j-1) negative electrode connection portion 52, the entire j positive electrode connection portion 62 is the first (j-1) negative electrode. The connection portion 52 and the j-th positive electrode connection portion 62 are located inside the outer edge of the (j-1) negative electrode connection portion 52 when viewed from the overlapping direction.

Although not shown, the minimum width of the positive electrode of the first positive electrode connection portion 62A is smaller than the minimum width of the negative electrode of the second negative electrode connection portion 52B, so that the entire first positive electrode connection portion 62A is the same as the second negative electrode connection portion 52B. It is located inside the outer edge of the second negative electrode connection portion 52B when viewed from the direction in which the first positive electrode connection portion 62A overlaps. Further, since the minimum positive electrode width of the 9th positive electrode connection portion 62I is smaller than the minimum negative electrode width of the 8th negative electrode connection portion 52H, the entire 9th positive electrode connection portion 62I is connected to the 8th negative electrode connection portion 52H and the 9th positive electrode connection. It is located inside the outer edge of the eighth negative electrode connecting portion 52H when viewed from the direction in which the portions 62I overlap. As described above, the entire positive electrode connecting portion 62 faces the main surface of the negative electrode connecting portion 52 via the separator 70.

As described above, in the battery 1 of the present embodiment, the negative electrode body 50 has a plurality of negative electrode bodies 51 arranged side by side in a row in the deployed state, and a pair of negative electrode bodies in which negative electrode active materials are arranged on the surface. The positive electrode body 60 has a plurality of positive electrode main bodies 61 that overlap with the negative electrode main body 51, and a plurality of negative electrode active materials are arranged on the surface of the positive electrode body 60. It has a plurality of positive electrode connection portions 62 facing the connection portion 52. According to this configuration, the negative electrode active material is arranged on the surface of the negative electrode connecting portion 52, and the positive electrode active material is arranged on the positive electrode connecting portion 62 facing the negative electrode connecting portion 52, so that the negative electrode main body 51 and the positive electrode main body are arranged. Not only 61 but also the negative electrode connection portion 52 and the positive electrode connection portion 62 can be charged and discharged. Therefore, the capacity of the battery 1 can be improved as compared with the configuration in which the active material is not arranged on the surfaces of the negative electrode connecting portion 52 and the positive electrode connecting portion 62.

Further, in the present embodiment, the negative electrode body 50 is wound by folding back the negative electrode connecting portion 52 so that the plurality of negative electrode bodies 51 overlap each other. Therefore, the negative electrode connecting portion 52 located at an odd number from the first negative electrode connecting portion 52A toward the outer peripheral side in the deployed state is arranged on one side in the axial direction with respect to the negative electrode main body 51 when viewed from the thickness direction. Further, the negative electrode connecting portion 52 located even-numbered from the first negative electrode connecting portion 52A toward the outer peripheral side in the deployed state is arranged on the other side in the axial direction with respect to the negative electrode main body 51 when viewed from the thickness direction.

FIG. 12 is a plan view showing a negative electrode body housed in the housing portion.
As shown in FIG. 12, according to the present embodiment, assuming that i is 3 or more and at least one integer equal to or less than the number of the plurality of negative electrode connecting portions 52, the i-th negative electrode connecting portions 52 and the second negative electrode connecting portions 52 adjacent to each other in the wound state. (I-2) With respect to the negative electrode connection portion 52, the width of the i-th negative electrode connection portion 52 on the outer layer side is narrower than the width of the (i-2) negative electrode connection portion 52 on the inner layer side when viewed from the thickness direction. .. As a result, the plurality of negative electrode main bodies 51 are arranged so as to gradually narrow the width as the i-th negative electrode connecting portion 52 and the (i-2) negative electrode connecting portion 52 move away from the negative electrode main body 51 when viewed from the thickness direction. Will be done. Therefore, the negative electrode body 50 can be wound into a desired flat shape having small irregularities when viewed from the thickness direction, and the negative electrode body 50 and the positive electrode body 60 can be arranged in the exterior body 10 without gaps. Therefore, it is possible to obtain the battery 1 which is compatible with exterior bodies having various shapes and whose capacity is secured.

Further, in the present embodiment, the negative electrode body 50 is wound by the first negative electrode body 51A and the second negative electrode body 51B so as to sandwich the first positive electrode body 61A, and the positive electrode body 60 is the first positive electrode body 61A and the second positive electrode body 61A. It is wound so as to sandwich the first negative electrode body 51A by the positive electrode body 61B. Therefore, the (i-1) positive electrode connecting portion 62 is arranged between the i-th negative electrode connecting portion 52 and the (i-2) negative electrode connecting portion 52 that are adjacent to each other in the wound state. According to the present embodiment, the minimum positive electrode width of the (i-1) positive electrode connection portion 62 is larger than the minimum negative electrode width of the i-th negative electrode connection portion 52 and the minimum negative electrode width of the (i-2) negative electrode connection portion 52. Is also small, so that the entire (i-1) positive electrode connection portion 62 faces the main surfaces of the i-th negative electrode connection portion 52 and the (i-2) negative electrode connection portion 52, respectively. As a result, it is possible to suppress the occurrence of electric field concentration at the outer edges of the i-th negative electrode connection portion 52 and the (i-2) negative electrode connection portion 52 during charging. Since the negative electrode active material is arranged on the surfaces of the i-th negative electrode connecting portion 52 and the (i-2) negative electrode connecting portion 52, lithium ions can be absorbed by the negative electrode active material, which is caused by electric field concentration. Therefore, it is possible to suppress the precipitation of needle-shaped lithium from the negative electrode body 50. Therefore, it is possible to suppress a short circuit between the negative electrode body 50 and the positive electrode body 60 and improve the reliability of the battery 1.

Further, in the present embodiment, assuming that j is 2 or more and all integers less than the number of the plurality of negative electrode connecting portions 52, the minimum positive electrode width of the j positive electrode connecting portion 62 is the negative electrode of the (j + 1) negative electrode connecting portion 52. It is smaller than the minimum width and the minimum width of the negative electrode of the (j-1) negative electrode connection portion 52. According to this configuration, all of the positive electrode connecting portions 62 arranged between the pair of negative electrode connecting portions 52 in the wound state of the plurality of positive electrode connecting portions 62 face the main surface of the negative electrode connecting portion 52. As a result, during charging, precipitation of lithium due to electric field concentration at the outer edges of all the negative electrode connection portions 52 can be suppressed. Therefore, it is possible to suppress a short circuit between the negative electrode body 50 and the positive electrode body 60 and improve the reliability of the battery 1.

Further, in the present embodiment, the minimum positive electrode width of the ninth positive electrode connection portion 62I is smaller than the minimum negative electrode width of the eighth negative electrode connection portion 52H. According to this configuration, all of the positive electrode connection portions 62 that overlap the negative electrode connection portion 52 from the outer layer side in the wound state of the plurality of positive electrode connection portions 62 face the main surface of the negative electrode connection portion 52. As a result, it is possible to more reliably suppress the precipitation of lithium due to the concentration of the electric field at the outer edges of all the negative electrode connection portions 52 during charging. Therefore, it is possible to suppress a short circuit between the negative electrode body 50 and the positive electrode body 60 and improve the reliability of the battery 1.

Further, in the present embodiment, the minimum positive electrode width of the first positive electrode connection portion 62A is smaller than the minimum negative electrode width of the second negative electrode connection portion 52B. According to this configuration, all of the positive electrode connection portions 62 that overlap the negative electrode connection portion 52 from the inner layer side in the wound state of the plurality of positive electrode connection portions 62 face the main surface of the negative electrode connection portion 52. As a result, it is possible to more reliably suppress the precipitation of lithium due to the concentration of the electric field at the outer edges of all the negative electrode connection portions 52 during charging. Therefore, it is possible to suppress a short circuit between the negative electrode body 50 and the positive electrode body 60 and improve the reliability of the battery 1.

Further, in the present embodiment, the plurality of negative electrode connecting portions 52 are arranged inside the both ends in the negative electrode lateral direction in the plurality of negative electrode main bodies 51. As described above, the plurality of negative electrode connecting portions 52 are arranged in the axial direction with respect to the negative electrode main body 51 when viewed from the thickness direction. According to the present embodiment, the plurality of negative electrode connecting portions 52 are arranged so as to project in the axial direction from the negative electrode main body 51 when viewed from the thickness direction. Here, in the configuration in which a plurality of negative electrode connecting portions protrude from the negative electrode main body with a constant width, a recess is formed in the joint portion between the negative electrode main body and the negative electrode connecting portion in the outer shape of the negative electrode body viewed from the thickness direction, and the exterior A gap is likely to be formed between the body and the body. Therefore, as described above, when viewed from the thickness direction, the i-th negative electrode connecting portion 52 and the (i-2) negative electrode connecting portion 52 are arranged so as to gradually narrow the width as the distance from the negative electrode main body 51 increases. The above-mentioned recess can be filled by the negative electrode connecting portion 52. Therefore, it is possible to use the battery 1 in which a gap is unlikely to be formed in the exterior body 10.

The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, in the above embodiment, the secondary battery has been described as an example of the electrochemical cell, but the present invention is not limited to this, and the above-described configuration may be applied to an electric double layer capacitor, a primary battery, and the like. Further, although the lithium ion secondary battery has been described as an example of the battery, the present invention is not limited to this, and a secondary battery other than the lithium ion secondary battery such as a metallic lithium secondary battery may be used.
When the above configuration is applied to the electric double layer capacitor, the electric double layer capacitor includes a pair of electrodes that are functionally indistinguishable between positive and negative, but one electrode is configured in the same manner as the negative electrode body and the other electrode. May be configured in the same manner as the positive electrode body.

Further, in the above embodiment, the same number of the plurality of negative electrode main bodies 51 and the plurality of positive electrode main bodies 61 are provided, but the present invention is not limited to this. One of the negative electrode body and the positive electrode body may be provided one more than the other.

Further, in the above embodiment, the electrode structure 40 is formed in a circular shape in a plan view, but the present invention is not limited to this. For example, the electrode structure may be formed in an oval shape in which the major axis or the minor axis is along the axial direction, a rhombic shape in which the diagonal line is along the axial direction, or the like.

Further, in the above embodiment, both the first container 20 and the second container 30 of the exterior body 10 are formed of the laminated film. However, the present invention is not limited to this, and one of the first container and the second container may be formed of a metal can made of stainless steel, aluminum, or the like.

In addition, it is possible to replace the components in the above-described embodiment with well-known components as appropriate without departing from the spirit of the present invention.

1 ... Battery (electrochemical cell) 50 ... Negative electrode body 51 ... Negative electrode body 52 ... Negative electrode connection part 52B ... Second negative electrode connection part 60 ... Positive electrode body 61 ... Positive electrode body 62 ... Positive electrode connection part 62A ... First positive electrode connection part W1 ... Minimum negative electrode width W2 ... Minimum positive electrode width

Claims (6)

It has a negative electrode body and a positive electrode body that are overlapped with each other and wound flat.
The negative electrode body is
Multiple negative electrode bodies arranged in a row in the first direction in the unfolded state,
A pair of negative electrode bodies that are adjacent to each other in a deployed state among the plurality of negative electrode bodies, a negative electrode active material is arranged on the surface, and a plurality of negative electrode connection portions that are folded back so that the pair of negative electrode bodies overlap each other.
Have,
The positive electrode body is
A plurality of positive electrode bodies arranged side by side in a second direction in the unfolded state and overlapping the negative electrode body,
A pair of positive electrode bodies that are adjacent to each other in a deployed state among the plurality of positive electrode bodies are connected, a positive electrode active material is arranged on the surface, and a plurality of positive electrode connection portions facing the plurality of negative electrode connection portions.
Have,
Let N be a natural number
Of the plurality of negative electrode connection portions, the negative electrode connection portion located Nth from the negative electrode connection portion arranged on the innermost circumference toward the outer peripheral side is defined as the Nth negative electrode connection portion.
Of the plurality of positive electrode connection portions, the positive electrode connection portion located Nth from the positive electrode connection portion arranged on the innermost circumference toward the outer peripheral side is defined as the Nth positive electrode connection portion.
In each of the plurality of negative electrode connection portions, the minimum width in the direction orthogonal to the first direction is defined as the negative electrode minimum width.
When the minimum width in the direction orthogonal to the second direction is defined as the minimum positive electrode width in each of the plurality of positive electrode connection portions,
The negative electrode body is wound by a pair of negative electrode bodies connected to the first negative electrode connecting portion of the plurality of negative electrode bodies so as to sandwich an end portion on the inner peripheral side of the positive electrode body.
The positive electrode body is wound by a pair of positive electrode bodies connected to the first positive electrode connecting portion of the plurality of positive electrode bodies so as to sandwich an end portion on the inner peripheral side of the negative electrode body.
Assuming that i is 3 or more and at least one integer equal to or less than the number of the plurality of negative electrode connection portions,
The minimum width of the negative electrode of the i-th negative electrode connection portion is smaller than the minimum width of the negative electrode of the (i-2) negative electrode connection portion.
The minimum positive electrode width of the (i-1) positive electrode connection portion is smaller than the minimum negative electrode width of the i-th negative electrode connection portion and the minimum negative electrode width of the (i-2) negative electrode connection portion.
An electrochemical cell characterized by that. Assuming that j is 2 or more and all integers less than the number of the plurality of negative electrode connection portions,
The minimum width of the positive electrode of the j-th positive electrode connection portion is smaller than the minimum width of the negative electrode of the (j + 1) negative electrode connection portion and the minimum width of the negative electrode of the (j-1) negative electrode connection portion.
The electrochemical cell according to claim 1. Assuming that k is the number of the plurality of negative electrode connection portions,
The minimum width of the positive electrode of the k-th positive electrode connection portion is smaller than the minimum width of the negative electrode of the (k-1) negative electrode connection portion.
The electrochemical cell according to claim 2. The minimum width of the positive electrode of the first positive electrode connection portion is smaller than the minimum width of the negative electrode of the second negative electrode connection portion.
The electrochemical cell according to claim 2 or 3, wherein the electrochemical cell is characterized in that. The plurality of negative electrode connecting portions are arranged inside the both ends of the plurality of negative electrode bodies in a direction orthogonal to the first direction.
The electrochemical cell according to any one of claims 1 to 4, wherein the electrochemical cell is characterized in that. The positive electrode active material contains a lithium compound.
The electrochemical cell according to any one of claims 1 to 5, wherein the electrochemical cell is characterized in that.

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