JP6752862B2 - Electrochemical cell - Google Patents

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. As a structure of an electrochemical cell, a structure is known in which a pair of strip-shaped electrodes are opposed to each other via a strip-shaped separator and housed in a case, and the electrodes and separator are impregnated with an electrolytic solution. For example, a structure in which a band-shaped electrode and a band-shaped separator are wound and housed in a tubular or coin-shaped case, or a structure in which the band-shaped electrode and the band-shaped separator are housed in a laminated film after being deformed into a flat shape are known.

Further, in Patent Document 1 below, 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 connecting pieces, and the laminated surfaces of the positive electrode plates and the laminated surfaces of the negative electrode plates are alternately formed via a separator. 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 so as to be laminated is disclosed.

International Publication No. 02/13305

However, in the above-mentioned prior art electrochemical cell, further improvement in capacity is desired.

Therefore, the present invention provides an electrochemical cell with an improved capacity.

The electrochemical cell of the present invention includes a negative electrode body and a positive electrode body that are overlapped with each other via a separator and wound flatly, and the negative electrode bodies are arranged side by side in the first direction in a deployed state, and the first At least one negative electrode connection in which a plurality of negative electrode bodies having a long axis oriented in a direction orthogonal to the direction and a pair of the negative electrode bodies adjacent to each other in the deployed state are connected 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 the second direction in the unfolded state, and are adjacent to each other in the unfolded state with a plurality of positive electrode bodies having a long axis oriented in a direction orthogonal to the second direction. The pair of positive electrode bodies are connected to each other, and the pair of positive electrode bodies have at least one positive electrode connecting portion folded back so as to overlap the negative electrode body, and the plurality of negative electrode bodies are arranged on the innermost circumference. The inner end side negative electrode main body is provided, the at least one negative electrode connection portion has an inner end side negative electrode connection portion connected to the inner end side negative electrode main body, and the plurality of positive electrode main bodies are arranged on the innermost circumference. The inner end side negative electrode body has an inner end side positive electrode body facing the inner end side negative electrode body via the separator, and the entire inner end side positive electrode body faces the negative electrode body via the separator and the inner end side. The side positive electrode body includes an outer edge extending along a direction orthogonal to the second direction and facing the inner end side negative electrode connection portion via the separator, and the long axis and the outer edge of the inner end side positive electrode body. the spacing state, and are more distance between the long axis and the inner end side negative electrode connecting portion of the inner end side negative electrode body, the plurality of negative electrode body, have a outer end anode body which is arranged in the outermost periphery However, the dimensions of the negative electrode body excluding the outer end side negative electrode body among the plurality of negative electrode bodies become smaller as the distance from the outer end side negative electrode body increases, and each of the at least one negative electrode connection portion The dimension in the first direction is characterized in that it increases as the distance from the inner end side negative electrode connection portion increases .

In a lithium ion battery, if the positive electrode body on which the positive electrode active material is arranged has a region that does not face the negative electrode body, the lithium ions that have moved from the positive electrode body during charging of the electrochemical cell face the positive electrode body due to the edge effect. There is a possibility that it will be concentrated in the edge of the negative electrode body and will be deposited in a needle shape. When lithium ions are deposited as lithium metal in this way, they may penetrate the separator and short-circuit the negative electrode body and the positive electrode body.
According to the present invention, the inner end side positive electrode main body is arranged between the layers of the pair of negative electrode main bodies including the inner end side negative electrode main body adjacent to the inner end side negative electrode connection portion. Further, the outer edge of the inner end side positive electrode body is surrounded by a pair of negative electrode bodies including the inner end side negative electrode body and an inner end side negative electrode connection portion. Therefore, it is possible to prevent the outer edge of the inner end side positive electrode body from protruding from the layers of the pair of negative electrode bodies to form a region on the inner end side positive electrode body that does not face the negative electrode body.
The distance between the long axis of the inner end side positive electrode body and the outer edge is greater than or equal to the distance between the long axis of the inner end side negative electrode body and the inner end side negative electrode connection portion. Therefore, when the inner end side positive electrode body is arranged so that the long axes overlap each other with respect to the inner end side negative electrode body, the inner end side positive electrode body surrounds the outer edge of the inner end side positive electrode body with the negative electrode body as described above. The area of the main body can be secured.
As described above, it is possible to provide an electrochemical cell having an improved capacity.
Here, attention is paid to a pair of negative electrode bodies that are adjacent to each other in the expanded state. As for the interval in the wound state of the pair of negative electrode bodies, the more the pair of negative electrode bodies are paired with the negative electrode bodies located on the outer peripheral side, the more the number of layers of the negative electrode bodies and the like arranged between the pair of negative electrode bodies increases. growing. According to the present invention, the dimension of the negative electrode connection portion in the first direction increases as the distance from the inner end side negative electrode connection portion increases, so that the distance between the pair of negative electrode bodies can be secured, and the pair of negative electrode bodies can be mutually wound. It is possible to suppress the misalignment of. Therefore, when viewed from the direction in which the plurality of negative electrode bodies overlap (hereinafter referred to as the stacking direction), the positional deviation of the plurality of negative electrode bodies is suppressed, and the negative electrode body can be wound into a desired flat shape.
Moreover, according to the present invention, the negative electrode body on the outer peripheral side of the pair of negative electrode bodies is formed larger in the first direction than the negative electrode body on the inner peripheral side. Therefore, in a state where the plurality of negative electrode bodies overlap each other, the negative electrode body on the outer peripheral side is provided with a non-overlapping region in which the negative electrode bodies on the inner peripheral side do not overlap when viewed from the stacking direction. By arranging the negative electrode connection portion connected to the negative electrode body on the inner peripheral side and extending in the stacking direction in the non-overlapping region of the negative electrode body on the outer peripheral side when viewed from the stacking direction, the negative electrode connection portion is located on the outer peripheral side when viewed from the stacking direction. It is possible to suppress the protrusion from the negative electrode body. Therefore, it is possible to wind the laminated electrode body into a desired flat shape without protrusions and arrange it in the exterior body at a high density.
As described above, the misalignment of the plurality of negative electrode bodies and the protrusion of the negative electrode connecting portions are suppressed when viewed from the stacking direction. Therefore, it is possible to provide an electrochemical cell in which the negative electrode body can be wound into a desired flat shape, the degree of freedom in shape is improved, and the capacity is secured.

In the above electrochemical cell, it is desirable that the entire outer edge of the inner end side positive electrode body faces the inner end side negative electrode connection portion via the separator.

According to the present invention, it is possible to more reliably prevent the outer edge of the inner end side positive electrode body from protruding from the inner end side negative electrode connection portion. As a result, it is possible to prevent the inner end side positive electrode body from forming a region that does not face the negative electrode body.

In the above-mentioned electrochemical cell, the separator is formed between the inner end side negative electrode connection portion and the outer edge of the inner end side positive electrode body, the inner end side negative electrode connection portion, and the outer edge of the inner end side positive electrode body. It is desirable to be in contact with.

According to the present invention, the outer shape of the inner end side positive electrode body can be expanded to the inner end side negative electrode connection portion side as much as possible while preventing a short circuit due to direct contact between the inner end side positive electrode body and the negative electrode body by the separator. it can. Therefore, it is possible to secure the area of the positive electrode body on the inner end side. Therefore, it is possible to provide an electrochemical cell with an improved capacity.

In the above electrochemical cell, it is desirable that the positive electrode body contains a lithium compound as a positive electrode active material.

According to the present invention, lithium ions can be absorbed by the negative electrode active material of the negative electrode body by avoiding the existence of the edge of the negative electrode body at the portion facing the positive electrode body on the inner end side. Therefore, it is possible to suppress the precipitation of needle-shaped lithium from the negative electrode body. Therefore, the reliability of the electrochemical cell can be improved.

According to the present invention, it is possible to provide an electrochemical cell having an improved capacity.

It is a perspective view of the battery of an embodiment. It is sectional drawing of the battery of an embodiment. It is sectional drawing of the laminated electrode body of an embodiment. It is sectional drawing which shows the part of the laminated electrode body of an embodiment enlarged. It is a perspective view which shows the laminated electrode body of an embodiment. It is a top view which shows the negative electrode body and the positive electrode body of an embodiment. It is a top view which shows the state which superposed the negative electrode body and the positive electrode body of an embodiment. It is a figure which shows the negative electrode body and the winding method of the positive electrode body of an embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, configurations having the same or similar functions are designated by the same reference numerals. Then, the overlapping 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 battery having an oval shape (rounded rectangular shape) in a plan view. The battery 1 is attached to the laminated electrode body 2, the electrolyte solution (not shown) impregnated in the laminated electrode body 2, the exterior body 3 containing the laminated electrode body 2, and the laminated electrode body 2. It includes one insulating tape 60 and a second insulating tape 70 (both see FIG. 5).

(Exterior body)
The exterior body 3 includes an accommodating portion 4 in which the laminated electrode body 2 is accommodated, and a sealing portion 5 bent along the outer circumference 4a of the accommodating portion 4. The sealing portion 5 is bent along the outer peripheral 4a of the accommodating portion 4 by, for example, drawing.

Further, the exterior body 3 includes a first container 10 and a second container 20 that sandwich the laminated electrode body 2 in between. The first container 10 and the second container 20 are each formed of a laminated film. The laminated film has a metal layer (metal foil), a resin fusion layer provided on the overlapping surface (inner side surface) and covering the metal foil, and a resin protective layer provided on the outer surface and covering the metal foil. 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 first container 10 includes an oval-shaped first bottom wall portion 11 and a first peripheral wall portion 12 extending in a tubular shape from the outer periphery of the first bottom wall portion 11. A first through hole 13 is formed in the first bottom wall portion 11. The first through hole 13 is formed in the center of the first bottom wall portion 11.

A copper plate 15 is heat-sealed on the inner surface of the first bottom wall portion 11 via a first sealant ring 14. The first sealant ring 14 is a ring-shaped sealant film formed by using a thermoplastic resin such as polyolefin polyethylene or polypropylene.

The inner surface of the copper plate 15 is connected to the negative electrode body 30 (see FIG. 3) described later of the laminated electrode body 2. A nickel plate 16 is welded to the center of the outer surface of the copper plate 15. The nickel plate 16 penetrates the first through hole 13 and is exposed to the outside, and functions as a negative electrode terminal of the battery 1. Further, if the copper plate 15 is made of nickel, the nickel plate 16 may not be provided.

The second container 20 has an oval-shaped second bottom wall portion 21, a second peripheral wall portion 22 extending in a tubular shape from the outer periphery of the second bottom wall portion 21, and a second peripheral wall portion 22 from the opening edge of the second peripheral wall portion 22. A bent portion 23 that is bent toward the outside of the portion 22 and extends toward the second bottom wall portion 21 is provided.

The second bottom wall portion 21 is arranged on the side opposite to the first bottom wall portion 11 of the first container 10 with the laminated electrode body 2 interposed therebetween. The second bottom wall portion 21 is formed to be slightly smaller than the first bottom wall portion 11 of the first container 10. A second through hole 24 is formed in the second bottom wall portion 21. The second through hole 24 is formed in the center of the second bottom wall portion 21.

An aluminum plate 26 is heat-sealed on the inner surface of the second bottom wall portion 21 via a second sealant ring 25. The second sealant ring 25 is made of a thermoplastic resin like the first sealant ring 14.

The inner surface of the aluminum plate 26 is connected to the positive electrode body 40 (see FIG. 3) described later of the laminated electrode body 2. A nickel plate 27 is welded to the center of the outer surface of the aluminum plate 26. The nickel plate 27 penetrates the second through hole 24 and is exposed to the outside, and functions as a positive electrode terminal of the battery 1. In addition, for example, instead of the aluminum plate 26, a plate material made of stainless steel can be used.

The second peripheral wall portion 22 extends from the outer periphery of the second bottom wall portion 21 toward the first bottom wall portion 11 of the first container 10. The second peripheral wall portion 22 forms the outer circumference 4a of the accommodating portion 4. The bent portion 23 is formed into a tubular shape from the end portion of the second peripheral wall portion 22 on the side of the first bottom wall portion 11 to the side of the second bottom wall portion 21 along the second peripheral wall portion 22. The bent portions 23 are arranged at intervals on the outside with respect to the second peripheral wall portion 22.

The second peripheral wall portion 22 is arranged inside the first peripheral wall portion 12 and inside the bent portion 23. Further, the bent portion 23 is arranged inside the first peripheral wall portion 12. The fusion layer of the bent portion 23 and the fusion layer of the first peripheral wall portion 12 are heat-sealed.

The sealing portion 5 is formed by heat-sealing the fusion layer of the bent portion 23 and the fusion layer of the first peripheral wall portion 12. Therefore, the outer circumference of the accommodating portion 4 is sealed by the sealing portion 5. As a result, the first container 10 and the second container 20 are overlapped to form the exterior body 3. The sealing portion 5 is formed in a tubular shape on the outside of the accommodating portion 4, and is bent along the outer circumference 4a of the accommodating portion 4.
A sealed space is formed in the accommodating portion 4 by superimposing the first container 10 and the second container 20. Specifically, the accommodating portion 4 is defined by the first bottom wall portion 11, the second bottom wall portion 21, and the second peripheral wall portion 22, and is formed in an oval shape in a plan view.

(Stacked electrode body)
FIG. 3 is a cross-sectional view of the laminated electrode body of the embodiment. FIG. 4 is an enlarged cross-sectional view showing a part of the laminated electrode body of the embodiment.
As shown in FIGS. 3 and 4, the laminated electrode body 2 includes a sheet-shaped negative electrode body 30, a positive electrode body 40, and a separator 50. The laminated electrode body 2 is a laminated type electrode body that is folded so that the negative electrode body 30 and the positive electrode body 40 are alternately laminated. Specifically, the laminated electrode body 2 is formed by superimposing the negative electrode body 30 and the positive electrode body 40 via the separator 50 and winding them flat. The negative electrode body 30 is connected to the copper plate 15 described above. The positive electrode body 40 is connected to the aluminum plate 26 described above.

The separator 50 is arranged between the negative electrode body 30 and the positive electrode body 40, and insulates the negative electrode body 30 and the positive electrode body 40. For example, the separator 50 is wound together with the negative electrode body 30 and the positive electrode body 40 in a state where the positive electrode body 40 is arranged so as to sandwich the positive electrode body 40 from both sides in the thickness direction thereof. Although the separator 50 is not shown in FIG. 3, the separator 50 is interposed between the negative electrode body 30 and the positive electrode body 40 at least in the entire region where the negative electrode body 30 and the positive electrode body 40 face each other. It is assumed that it is located in. Hereinafter, the direction in which the negative electrode body 30 and the positive electrode body 40 are alternately laminated is referred to as a stacking direction. Note that winding means winding so as to orbit around a specific position in one direction.

The negative electrode body 30 is a sheet-shaped 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 40 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 50 is a member having a property of passing lithium ions. The separator 50 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.

FIG. 5 is a perspective view showing the laminated electrode body of the embodiment. In FIG. 5, the separator 50 arranged along the outer peripheral surface and the inner peripheral surface of the negative electrode body 30 is shown by hatching, ignoring the thickness. Further, since a part of the positive electrode body 40 is formed smaller than the negative electrode body 30 as described later, it is exposed on the surface of the laminated electrode body 2 from the viewpoint of FIG. 5 by being arranged between the layers of the negative electrode body 30. Not done.
As shown in FIG. 5, the laminated electrode body 2 is formed in a shape corresponding to the shape of the sealed space in the housing portion 4 so as to be arranged at a high density in the housing portion 4 of the exterior body 3 ( (See FIG. 2). That is, the laminated electrode body 2 is formed in an oval shape (rounded rectangular shape) when viewed from the stacking direction. The shape of the laminated electrode body 2 viewed from the stacking direction is defined as the basic shape.

Here, the shape of the negative electrode body 30 in the deployed state of the laminated electrode body 2 will be described.
FIG. 6 is a plan view showing the negative electrode body and the positive electrode body of the embodiment.
As shown in FIG. 6, the negative electrode body 30 is at least one (not shown) that connects a plurality of (8 in the illustrated example) negative electrode bodies 31 arranged side by side in a row and a pair of adjacent negative electrode bodies 31. In the example, 7) negative electrode connection portions 32 and negative electrode tabs 35 extending from the negative electrode main body 31 are provided. Have. The negative electrode body 31 is a portion of the laminated electrode body 2 that extends flat along a vertical plane in the stacking direction (see FIGS. 3 and 5). The negative electrode connecting portion 32 is a portion that is folded back at the side portion of the laminated electrode body 2 so that the plurality of negative electrode bodies 31 overlap each other (see FIGS. 3 and 5). The negative electrode tab 35 is a portion connected to the copper plate 15 described above. A negative electrode active material is arranged on the entire surface of each of the negative electrode main body 31 and the negative electrode connection portion 32. The negative electrode current collecting foil is exposed on the surface of the tip of the negative electrode tab 35.

Hereinafter, the direction in which the plurality of negative electrode bodies 31 are lined up is referred to as a negative electrode connecting direction (first direction), and the direction orthogonal to the negative electrode connecting direction is referred to as a negative electrode width direction. Further, in the negative electrode connecting direction, the negative electrode body 31 side arranged on the outer peripheral side of the laminated electrode body 2 is opposed to the negative electrode body 31 arranged on the most winding center side of the laminated electrode body 2 among the plurality of negative electrode bodies 31. It is defined as "outer circumference side", and the opposite direction is defined as "inner circumference side". Further, in the following, the plurality of negative electrode main bodies 31 will be described with ordinal numbers in order from the innermost peripheral negative electrode main body 31 to the outer peripheral side. In other words, N is a natural number, and the Nth negative electrode body counted from the innermost negative electrode body 31 to the outer peripheral side is referred to as the Nth negative electrode body. For example, the innermost negative electrode body 31 is the first negative electrode body. The same applies to the plurality of negative electrode connection portions 32. The first negative electrode body is an example of the “inner end side negative electrode body”. The eighth negative electrode body is an example of the “outer end side negative electrode body”. The first negative electrode connection portion is an example of the “inner end side negative electrode connection portion”.

The plurality of negative electrode bodies 31 are arranged so that the centers in the negative electrode width direction are overlapped with each other when viewed from the negative electrode connecting direction. The plurality of negative electrode bodies 31 are formed in a shape in which a part of the basic shape is missing. That is, the plurality of negative electrode main bodies 31 are formed in a shape in which a part of the oval shape is missing. The plurality of negative electrode bodies 31 are arranged so that the long axis A1 points in the negative electrode width direction. The outer shape of each negative electrode body 31 is formed by a pair of straight portions 33 extending linearly in the width direction of the negative electrode and a pair of arcuate curved portions 34 connecting the ends of the pair of straight portions 33. .. The curved portion 34 constitutes a part of the outer edge of the negative electrode body 30 that faces the negative electrode width direction. In the negative electrode body 31 excluding the eighth negative electrode body 31H arranged on the outermost periphery of the negative electrode body 31, the entire straight portion 33 in the negative electrode connecting direction is described so as to reduce the dimension in the negative electrode connecting direction with respect to the basic shape. It is provided closer to the long axis A1 with respect to the basic shape. Of the plurality of negative electrode bodies 31, the dimension D1 in the negative electrode connection direction of each of the negative electrode bodies 31 excluding the eighth negative electrode body 31H becomes smaller as the distance from the eighth negative electrode body 31H increases. In other words, among the plurality of negative electrode main bodies 31, the negative electrode main body 31 excluding the eighth negative electrode main body 31H is formed larger in the negative electrode connecting direction than the negative electrode main body 31 adjacent to the inner peripheral side.

The outer shape of the eighth negative electrode body 31H is smaller than the outer shape of the sixth negative electrode body 31F arranged on the two inner peripheral sides of the eighth negative electrode body 31H. That is, the eighth negative electrode main body 31H is formed so as to overlap the sixth negative electrode main body 31F as a whole when it is overlapped with the sixth negative electrode main body 31F. The sixth negative electrode body 31F is a negative electrode body 31 arranged one layer inside the eighth negative electrode body 31H in a wound state.

The plurality of negative electrode connecting portions 32 are provided between a pair of negative electrode main bodies 31 adjacent to each other in the negative electrode connecting direction. Each negative electrode connecting portion 32 is formed so that the intermediate portion in the negative electrode connecting direction has the narrowest width. The intermediate portion means not only the center between both ends of the target but also the inner range between both ends of the target. The outer edges of the negative electrode connecting portion 32 on both sides in the negative electrode width direction extend in an arc shape recessed in the negative electrode width direction. The outer edges of the negative electrode connecting portion 32 on both sides in the negative electrode width direction are continuously connected to the curved portion 34 of the negative electrode main body 31. Specifically, the outer edges of the negative electrode connecting portion 32 on both sides in the negative electrode width direction are connected to the curved portion 34 of the negative electrode main body 31 via an inflection point. In other words, a straight line extending in the negative electrode width direction through the inflection point at the outer edge of the negative electrode body 30 in the negative electrode width direction becomes the boundary between the negative electrode body 31 and the negative electrode connection portion 32. The dimension D2 of the plurality of negative electrode connecting portions 32 in the negative electrode connecting direction increases as the distance from the first negative electrode connecting portion 32A arranged on the innermost circumference increases. In other words, the plurality of negative electrode connecting portions 32 are formed larger in the negative electrode connecting direction than the negative electrode connecting portions 32 adjacent to each other on the inner peripheral side.

The negative electrode tab 35 extends from the eighth negative electrode body 31H to the side opposite to the first negative electrode body 31A. The negative electrode tab 35 extends in the negative electrode connecting direction with a width narrower than that of the plurality of negative electrode connecting portions 32. The negative electrode tab 35 is connected to the entire straight portion 33 on the outer peripheral side of the eighth negative electrode main body 31H. The outer edge of the negative electrode tab 35 is connected to the pair of curved portions 34 of the eighth negative electrode main body 31H via an inflection point.

Next, the shape of the positive electrode body 40 in the deployed state of the laminated electrode body 2 will be described.
The positive electrode body 40 is a plurality of (8 in the illustrated example) positive electrode bodies 41 arranged side by side in a row and at least one (7 in the illustrated example) positive electrode connecting a pair of adjacent positive electrode bodies 41. It has a connecting portion 42 and a positive electrode tab 45 extending from the positive electrode main body 41. The positive electrode body 41 is a portion of the laminated electrode body 2 that extends flatly along a vertical plane in the stacking direction (see FIG. 3). The positive electrode connecting portion 42 is a portion that is folded back at the side portion of the laminated electrode body 2 so that the plurality of positive electrode main bodies 41 overlap the negative electrode main body 31 (see FIG. 3). The positive electrode tab 45 is a portion connected to the aluminum plate 26 described above. A positive electrode active material is arranged on the entire surface of each of the positive electrode body 41 and the positive electrode connection portion 42. The positive electrode current collecting foil is exposed on the surface of the tip of the positive electrode tab 45.

Hereinafter, the direction in which the plurality of positive electrode bodies 41 are lined up is referred to as a positive electrode connecting direction (second direction), and the direction orthogonal to the positive electrode connecting direction is referred to as a positive electrode width direction. Further, in the positive electrode connecting direction, the positive electrode body 41 arranged on the outer peripheral side of the laminated electrode body 2 is "" with respect to the positive electrode body 41 arranged on the most winding center side of the laminated electrode body among the plurality of positive electrode bodies 41. 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 41 and the plurality of positive electrode connecting portions 42 will be described with ordinal numbers in the same manner as the negative electrode main body 31 and the negative electrode connecting portions 32. The first positive electrode body is an example of the “inner end side positive electrode body”.

The plurality of positive electrode main bodies 41 are provided in the same number as the negative electrode main bodies 31. The plurality of positive electrode bodies 41 are arranged so that the centers in the positive electrode width direction are overlapped with each other when viewed from the positive electrode connecting direction. The outer shape of each positive electrode body 41 is formed by a pair of straight portions 43 extending in the width direction of the positive electrode and a pair of arcuate curved portions 44 connecting the ends of the pair of straight portions 43. The plurality of positive electrode bodies 41 are formed in a shape in which the straight line portion 43 is provided closer to the long axis A2 with respect to an elliptical shape having the long axis A2 directed in the positive electrode width direction. The positive electrode body 41 other than the first positive electrode body 41A arranged on the innermost circumference of the plurality of positive electrode bodies 41 is formed smaller than the outer shape of the negative electrode body 31 facing each other via the separator 50 in the laminated electrode body 2. .. For example, the outer shape of the seventh positive electrode body 41G is smaller than the outer shape of the eighth negative electrode body 31H and the sixth negative electrode body 31F facing each other via the separator 50. The outer shape of the eighth positive electrode body 41H is smaller than the outer shape of the seventh negative electrode body 31G facing each other via the separator 50.

FIG. 7 is a plan view showing a state in which the negative electrode body and the positive electrode body of the embodiment are overlapped with each other.
Here, as shown in FIG. 7, a reference numeral 43a is attached to a straight portion 43 on the opposite side of the pair of linear portions 43 of the first positive electrode main body 41A to the second positive electrode main body 41B. The straight portion 43a of the first positive electrode body 41A constitutes a part of the outer edge of the positive electrode body 40. The entire straight portion 43a of the first positive electrode body 41A faces the first negative electrode connecting portion 32A via the separator 50 (see also FIG. 4). The distance G1 between the straight portion 43a of the first positive electrode body 41A and the long axis A2 of the first positive electrode body 41A is equal to or greater than the distance G2 between the long axis A1 of the first negative electrode body 31A and the first negative electrode connecting portion 32A. .. As a result, the separator 50 is in contact with the straight portion 43a of the first negative electrode connecting portion 32A and the first positive electrode main body 41A between the first negative electrode connecting portion 32A and the straight portion 43a of the first positive electrode main body 41A ( (See FIG. 4). In the illustrated example, the distance G1 between the straight portion 43a of the first positive electrode body 41A and the major axis A2 of the first positive electrode body 41A is the distance G2 between the major axis A1 of the first negative electrode body 31A and the first negative electrode connecting portion 32A. Is consistent with.

As shown in FIG. 6, a plurality of positive electrode connecting portions 42 are provided between a pair of positive electrode main bodies 41 adjacent to each other in the positive electrode connecting direction. Each positive electrode connecting portion 42 is formed so that the intermediate portion in the positive electrode connecting direction is the narrowest. The outer edges of the positive electrode connecting portion 42 on both sides in the positive electrode width direction extend in an arc shape recessed in the positive electrode width direction. The outer edges of the positive electrode connecting portion 42 on both sides in the positive electrode width direction are continuously connected to the curved portion 44 of the positive electrode main body 41. Specifically, the outer edges of the positive electrode connecting portion 42 on both sides in the positive electrode width direction are connected to the curved portion 44 of the positive electrode main body 41 via an inflection point. In other words, a straight line extending in the positive electrode width direction through the inflection point at the outer edge of the positive electrode body 40 in the positive electrode width direction becomes the boundary between the positive electrode main body 41 and the positive electrode connecting portion 42.

The dimensions of the positive electrode connecting portion 42 in the positive electrode connecting direction are set based on the following conditions. In the Nth positive electrode connecting portion 42, the distance D3 between the long axis A2 of the Nth positive electrode main body 41 and the (N + 1) positive electrode main body 41 adjacent to the Nth positive electrode connecting portion 42 is the Nth negative electrode main body 31 and the (N + 1) th. It is formed so as to match the distance D4 between the major axes A1 of the negative electrode body 31. For example, the distance between the major axis A2 of the first positive electrode body 41A and the major axis A2 of the second positive electrode body 41B is one with the distance between the major axis A1 of the first negative electrode body 31A and the major axis A1 of the second negative electrode body 31B. I am doing it.

The positive electrode tab 45 extends from the eighth positive electrode body 41H to the side opposite to the first positive electrode body 41A. The positive electrode tab 45 extends in the positive electrode connecting direction with a width narrower than that of the plurality of positive electrode connecting portions 42. The positive electrode tab 45 is connected to the entire straight portion 43 on the outer peripheral side of the eighth positive electrode body 41H. The outer edge of the positive electrode tab 45 is connected to the pair of curved portions 44 of the eighth positive electrode main body 41H via an inflection point.

Next, the winding structure of the negative electrode body 30 and the positive electrode body 40 will be described.
FIG. 8 is a diagram showing a method of winding the negative electrode body and the positive electrode body of the embodiment.
As shown in FIG. 8, first, the first negative electrode main body 31A of the negative electrode body 30 and the first positive electrode main body 41A of the positive electrode body 40 are overlapped with each other. At this time, in the first negative electrode body 31A and the first positive electrode body 41A, the major axes A1 and A2 (see FIGS. 6 and 7) overlap each other, and the center point of the major axis A1 and the center point of the major axis A2 are overlapped with each other. And are arranged so as to overlap. Further, the negative electrode body 30 and the positive electrode body 40 are arranged so as to extend in opposite directions from the first negative electrode body 31A and the first positive electrode body 41A. Hereinafter, the portion where the first negative electrode main body 31A and the first positive electrode main body 41A are overlapped is referred to as a reference overlapping portion.

Subsequently, the negative electrode body 30 and the positive electrode body 40 are wound around the reference overlapping portion so that the reference overlapping portion is the winding center. Specifically, the negative electrode body 30 and the positive electrode body 40 are wound by the following procedure. The first negative electrode connection portion 32A of the negative electrode body 30 is folded back, and the second negative electrode body 31B is overlapped with the first positive electrode body 41A on the side opposite to the first negative electrode body 31A. At this time, the first negative electrode body 31A and the second negative electrode body 31B are arranged so that the major axes A1 overlap each other when viewed from the stacking direction. Further, the first positive electrode connection portion 42A of the positive electrode body 40 is folded back, and the second positive electrode main body 41B is overlapped with the first negative electrode main body 31A on the side opposite to the first positive electrode main body 41A. At this time, the first positive electrode body 41A and the second positive electrode body 41B are arranged so that their major axes A2 overlap each other when viewed from the stacking direction. After that, the negative electrode connecting portions 32 are folded back so that the negative electrode main bodies 31 overlap each other, and the positive electrode connecting portions 42 are folded back so that the positive electrode main bodies 41 overlap each other. As a result, the winding of the negative electrode body 30 and the positive electrode body 40 is completed. After that, the negative electrode tab 35 is folded back along the outer peripheral surface of the eighth negative electrode main body 31H, and the positive electrode tab 45 is folded back along the outer peripheral surface of the eighth positive electrode main body 41H. At this time, the negative electrode tab 35 is folded back so that the portion of the negative electrode tab 35 where the negative electrode current collecting foil is exposed does not face the positive electrode body 40.

For example, the first negative electrode connecting portion 32A may be bent first, and the first positive electrode main body 41A may be inserted between the layers of the first negative electrode main body 31A and the second negative electrode main body 31B to start winding. In this case, the first positive electrode is sandwiched between the first negative electrode body 31A and the second negative electrode body 31B so that the straight portion 43a (see FIG. 7) of the first positive electrode body 41A abuts against the first negative electrode connecting portion 32A. The main body 41A can be inserted.

Although not shown, the separator 50 is formed in a band shape wider than both the negative electrode body 30 and the positive electrode body 40, and after being wound together with the negative electrode body 30 and the positive electrode body 40, the negative electrode body 30 is viewed from the stacking direction. The excess part is cut off along the outer shape of. As a result, the separator 50 is arranged along substantially the entire inner peripheral surface and outer peripheral surface of each of the negative electrode body 30 and the positive electrode body 40.

As described above, in the present embodiment, the first positive electrode main body 41A includes a straight line portion 43a facing the inner end side negative electrode connecting portion via the separator 50, and has a long axis A2 of the first positive electrode main body 41A. The distance G1 from the straight portion 43a is equal to or greater than the distance G2 between the long axis A1 of the first negative electrode body 31A and the first negative electrode connecting portion 32A.
According to this configuration, the first positive electrode body 41A is arranged between the layers of the pair of negative electrode bodies 31 including the first negative electrode body 31A adjacent to the first negative electrode connecting portion 32A. Further, the straight portion 43a of the first positive electrode main body 41A is surrounded by a pair of negative electrode main bodies 31 including the first negative electrode main body 31A and the first negative electrode connecting portion 32A. Therefore, it is possible to prevent the straight portion 43a of the first positive electrode body 41A from protruding from the layers of the pair of negative electrode bodies 31 to form a region in the first positive electrode body 41A that does not face the negative electrode body 30.
The distance between the long axis A2 of the first positive electrode body 41A and the straight portion 43a is equal to or greater than the distance between the long axis A1 of the first negative electrode body 31A and the first negative electrode connecting portion 32A. Therefore, when the first positive electrode body 41A is arranged so that the major axes A1 and A2 overlap each other with respect to the first negative electrode body 31A, the negative electrode body 30 surrounds the straight portion 43a of the first positive electrode body 41A as described above. At the same time, the area of the first positive electrode body 41A can be secured.
As described above, the battery 1 having an improved capacity can be provided.

Further, the straight portion 43a of the first positive electrode body 41A is surrounded by the negative electrode body 30. Therefore, when the negative electrode body 30 and the positive electrode body 40 are wound, the straight portion 43a of the first positive electrode body 41A is the first negative electrode with respect to the negative electrode body 30 in which the first negative electrode connecting portion 32A is bent. It can be inserted between the layers of the pair of negative electrode bodies 31 including the first negative electrode body 31A so as to abut against the connection portion 32A. Therefore, the positional deviation when the negative electrode body 30 and the positive electrode body 40 are wound can be suppressed, so that the battery 1 can be easily manufactured.

Further, the entire straight portion 43a of the first positive electrode body 41A faces the first negative electrode connecting portion 32A via the separator 50. According to this configuration, it is possible to more reliably prevent the straight portion 43a of the first positive electrode main body 41A from protruding from the first negative electrode connecting portion 32A. As a result, it is possible to prevent the first positive electrode body 41A from forming a region that does not face the negative electrode body 30.

Further, the separator 50 is in contact with the first negative electrode connecting portion 32A and the straight portion 43a of the first positive electrode main body 41A between the first negative electrode connecting portion 32A and the straight portion 43a of the first positive electrode main body 41A. According to this configuration, the separator 50 prevents a short circuit due to direct contact between the first positive electrode body 41A and the negative electrode body 30, while maximizing the outer shape of the first positive electrode body 41A toward the first negative electrode connecting portion 32A. be able to. Therefore, it is possible to secure the area of the first positive electrode body 41A. Therefore, it is possible to provide the battery 1 having an improved capacity.

Further, the dimensions of each of the negative electrode connecting portions 32 in the negative electrode connecting direction become larger as the distance from the first negative electrode main body 31A increases.
Here, attention is paid to a pair of negative electrode main bodies 31 that are adjacent to each other in the deployed state, except for the eighth negative electrode main body 31H among the plurality of negative electrode main bodies 31. The distance between the pair of negative electrode bodies 31 in the wound state is such that the pair of negative electrode bodies 31 is paired with the negative electrode bodies 31 located on the outer peripheral side, the layers such as the negative electrode bodies 31 arranged between the pair of negative electrode bodies 31. As the number increases, it becomes larger. According to the present embodiment, the dimension of the negative electrode connecting portion in the first direction increases as the distance from the first negative electrode connecting portion 32A increases, so that the distance between the pair of negative electrode main bodies 31 can be secured and the pair of negative electrode main bodies 31 are wound. It is possible to suppress the displacement of each other in the state. Therefore, when viewed from the stacking direction, the misalignment of the plurality of negative electrode bodies 31 is suppressed, and the negative electrode body 30 can be wound into a desired flat shape.
Moreover, the dimension of each of the at least one negative electrode connecting portion 32 in the negative electrode connecting direction increases as the distance from the first negative electrode connecting portion 32A increases. According to this configuration, the negative electrode main body 31 on the outer peripheral side of the pair of negative electrode main bodies 31 is formed larger in the negative electrode connecting direction than the negative electrode main body 31 on the inner peripheral side. Therefore, in a state where the plurality of negative electrode bodies 31 overlap each other, the negative electrode body 31 on the outer peripheral side is provided with a non-overlapping region in which the negative electrode bodies 31 on the inner peripheral side do not overlap when viewed from the stacking direction. For example, as shown in FIG. 3, the seventh negative electrode body 31G is provided with a non-overlapping region R in which the sixth negative electrode body 31F does not overlap when viewed from the stacking direction. By arranging the negative electrode connecting portion 32 connected to the negative electrode main body 31 on the inner peripheral side and extending in the stacking direction in the non-overlapping region of the negative electrode main body 31 on the outer peripheral side when viewed from the stacking direction, the negative electrode connecting portion is viewed from the stacking direction. It is possible to prevent the 32 from protruding from the negative electrode body 31 on the outer peripheral side. Therefore, the laminated electrode body 2 can be wound into a desired flat shape without protrusions and arranged in the exterior body 3 at a high density.
As a result, the misalignment of the plurality of negative electrode bodies 31 and the protrusion of the negative electrode connecting portions 32 are suppressed when viewed from the stacking direction. Therefore, it is possible to provide the battery 1 in which the negative electrode body 30 can be wound into a desired flat shape, the degree of freedom in the shape is improved, and the capacity is secured.

Further, the positive electrode body 40 contains a lithium compound as a positive electrode active material. In the present embodiment, as described above, since it is avoided that the edge of the negative electrode body 30 is present at the portion facing the first positive electrode body 41A, lithium ions are absorbed by the negative electrode active material of the negative electrode body 30. be able to. Therefore, it is possible to suppress the precipitation of needle-shaped lithium from the negative electrode body 30. Therefore, the reliability of the battery 1 can be improved.

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 laminated electrode body 2 is formed in an oval shape when viewed from the stacking direction, but the present invention is not limited to this, and various shapes can be formed depending on the shape of the exterior body. For example, the laminated electrode body may be formed in a circular shape or an elliptical shape when viewed from the stacking direction, or may be formed in a quadrangular shape such as a rhombus or a rectangle.

Further, in the above embodiment, the battery 1 includes, but is not limited to, a positive electrode terminal and a negative electrode terminal exposed through the through hole of the exterior body 3. The battery may be provided with a tab-shaped terminal extending from the inside of the exterior body to the outside through between the first container and the second container at the sealing portion of the exterior body.

Further, in the above embodiment, the first container 10 is provided with the negative electrode terminal, and the second container 20 is provided with the positive electrode terminal, but the present invention is not limited to this. That is, the positive electrode terminal may be provided in the first container and the negative electrode terminal may be provided in the second container.

Further, in the above embodiment, the distance G1 between the straight portion 43a of the first positive electrode main body 41A and the long axis A2 of the first positive electrode main body 41A is set between the long axis A1 of the first negative electrode main body 31A and the first negative electrode connecting portion 32A. Matches, but is not limited to, the interval G2. Even if the distance G1 between the straight portion 43a of the first positive electrode body 41A and the long axis A2 of the first positive electrode body 41A is larger than the distance G2 between the long axis A1 of the first negative electrode body 31A and the first negative electrode connecting portion 32A. Good. In this case, the straight portion 43a of the first positive electrode main body 41A is arranged outside the first negative electrode main body 31A and the second negative electrode main body 31B when viewed from the stacking direction so as to be surrounded by the first negative electrode connecting portion 32A. Therefore, it is possible to prevent the first positive electrode body 41A from forming a region that does not face the negative electrode body 30.

Further, in the above embodiment, since the outer shape of the eighth negative electrode body 31H is smaller than the outer shape of the sixth negative electrode body 31F, the dimensions of the eighth negative electrode body 31H in the negative electrode connection direction are adjacent to the inner peripheral side in the deployed state. 7 The size of the negative electrode body 31G is smaller than the size in the negative electrode connection direction. However, the present invention is not limited to this, and the dimension of the eighth negative electrode main body in the negative electrode connecting direction may be larger than the dimension of the seventh negative electrode main body 31G in the negative electrode connecting direction. That is, the dimensions of all the negative electrode bodies in the negative electrode connecting direction may become smaller as the distance from the eighth negative electrode body increases. As a result, it is possible to prevent the negative electrode connecting portion 32 from protruding from the eighth negative electrode main body when viewed from the stacking direction, and the negative electrode body can be more reliably formed into a desired flat shape. However, as in the above embodiment, by making the outer shape of the 8th negative electrode body 31H smaller than the outer shape of the 6th negative electrode body 31F, an insulating tape for preventing unwinding is attached around the 8th negative electrode body 31H. A allowance can be provided.

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

1 ... Battery (electrochemical cell) 30 ... Negative electrode body 31 ... Negative electrode body 31A ... 1st negative electrode body (inner end side negative electrode body) 31H ... 8th negative electrode body (outer end side negative electrode body) 32 ... Negative electrode connection part 32A ... 1 Negative electrode connection part (inner end side negative electrode connection part) 40 ... Positive electrode body 41 ... Positive electrode body 41A ... First positive electrode body (inner end side positive electrode body) 42 ... Positive electrode connection part 43a ... Straight part (outer edge) 50 ... Separator A1 ... Long axis A2 ... Long axis

Claims (4)

It is provided with a negative electrode body and a positive electrode body which are overlapped with each other via a separator and wound flat.
The negative electrode body
A plurality of negative electrode bodies arranged side by side in the first direction in the unfolded state and having a long axis oriented in a direction orthogonal to the first direction.
At least one negative electrode connection portion in which the pair of adjacent negative electrode bodies are connected in the expanded state and the pair of negative electrode bodies are folded back so as to overlap each other.
Have,
The positive electrode body is
A plurality of positive electrode bodies arranged side by side in the second direction in the unfolded state and having a long axis oriented in a direction orthogonal to the second direction.
At least one positive electrode connection portion in which the pair of positive electrode bodies adjacent to each other in the expanded state are connected and the pair of positive electrode bodies are folded back so as to overlap the negative electrode body.
Have,
The plurality of negative electrode bodies have an inner end side negative electrode body arranged on the innermost circumference.
The at least one negative electrode connecting portion has an inner end side negative electrode connecting portion connected to the inner end side negative electrode main body.
The plurality of positive electrode bodies are arranged on the innermost circumference, and have an inner end side positive electrode body facing the inner end side negative electrode body via the separator.
The entire inner end side positive electrode body faces the negative electrode body via the separator.
The inner end side positive electrode body includes an outer edge extending along a direction orthogonal to the second direction and facing the inner end side negative electrode connection portion via the separator.
Distance between the outer edge and the long axis of the inner end side positive electrode body state, and are more distance between the long axis and the inner end side negative electrode connecting portion of the inner end side negative electrode body,
The plurality of negative electrode bodies have an outer end side negative electrode body arranged on the outermost circumference.
Of the plurality of negative electrode bodies, the dimensions of the negative electrode body excluding the outer end side negative electrode body become smaller as the distance from the outer end side negative electrode body increases.
The dimension of each of the at least one negative electrode connection portion in the first direction increases as the distance from the inner end side negative electrode connection portion increases.
An electrochemical cell characterized by that. The entire outer edge of the inner end side positive electrode body faces the inner end side negative electrode connection portion via the separator.
The electrochemical cell according to claim 1. The separator is in contact with the inner end side negative electrode connection portion and the outer edge of the inner end side positive electrode body between the inner end side negative electrode connection portion and the outer edge of the inner end side positive electrode body.
The electrochemical cell according to claim 1 or 2, wherein the electrochemical cell is characterized in that. The positive electrode body contains a lithium compound as a positive electrode active material.
The electrochemical cell according to any one of claims 1 to 3 , wherein the electrochemical cell is characterized in that.

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