JP7538293B2 - Laminated electrode body - Google Patents

Description

The present invention relates to a laminated electrode body.

2. Description of the Related Art Lithium-ion secondary batteries, electrochemical capacitors, and other electrochemical cells have traditionally been widely used as power sources for small devices such as smartphones, wearable devices, and hearing aids.
In recent years, a so-called laminate-type electrochemical cell has been known as this type of electrochemical cell, which uses a laminate film for an exterior body that houses an electrode assembly inside. This laminate-type electrochemical cell is known as an electrochemical cell that is small in size, has a high degree of freedom in shape, and can be further increased in capacity.

For example, Patent Document 1 listed below discloses an electrochemical cell including an electrode body and an exterior body having a first laminate member and a second laminate member and housing the electrode body between the first laminate member and the second laminate member.
The electrode assembly is structured to include negative and positive electrodes alternately stacked with a separator interposed therebetween. The negative electrode has a negative electrode terminal tab and is connected to, for example, a copper plate or the like that functions as the negative electrode plate. Similarly, the positive electrode has a positive electrode terminal tab and is connected to, for example, an aluminum plate or the like that functions as the positive electrode plate.

JP 2018-85214 A

In the above-mentioned conventional laminate-type electrochemical cells, the outer shape of the negative electrode is generally formed to be larger than the outer shape of the positive electrode.
For example, in the case of a lithium-ion battery, a phenomenon called electrodeposition may occur during charging, in which lithium ions that have migrated from the positive electrode side to the negative electrode side are deposited as lithium metal on the surface of the negative electrode. In this case, for example, the lithium metal may concentrate on the edge of the negative electrode and deposit in a needle-like shape. Therefore, if the external shape of the negative electrode is smaller than that of the positive electrode, the lithium metal deposited in a needle-like shape may penetrate the separator and reach the positive electrode, which may cause an internal short circuit.
Therefore, in order to prevent the occurrence of such an internal short circuit, the outer shape of the negative electrode is often formed to be larger than the outer shape of the positive electrode.

However, even if the outer shape of the negative electrode is formed to be larger than the outer shape of the positive electrode, the electrode body may be stored in a state in which the negative electrode terminal tab is positioned opposite the positive electrode via the separator.
Usually, the negative electrode terminal tab is folded back from its base side as a base point, and is connected to a copper plate or the like in a state where it is not arranged opposite the positive electrode through the separator. However, for some reason, such as not being folded back properly, the negative electrode terminal tab may be arranged opposite the positive electrode through the separator as described above. In this case, as in the case described above, there is a possibility that lithium metal may precipitate in a needle-like shape on the negative electrode terminal tab and penetrate the separator to reach the positive electrode. Therefore, there is a risk of an internal short circuit, and there is room for improvement.

The present invention was made in consideration of these circumstances, and its purpose is to provide a laminated electrode body that can reduce the possibility of an internal short circuit caused by the negative electrode terminal tab.

(1) The laminated electrode body of the present invention is a laminated electrode body that is housed inside the exterior body of an electrochemical cell and to which an insulating tape having a first insulating tape and a second insulating tape having an extension tape portion is attached, and includes a positive electrode and a negative electrode that is overlapped on the positive electrode via a separator, and the positive electrode includes a plurality of positive electrode bodies arranged along the stacking direction of the laminated electrode body, a positive electrode connection piece that connects the plurality of positive electrode bodies to each other, and a positive electrode terminal tab that is integrally formed with one of the plurality of positive electrode bodies, and the negative electrode includes a plurality of negative electrode bodies arranged along the stacking direction of the laminated electrode body, a negative electrode connection piece that connects the plurality of negative electrode bodies to each other, and a negative electrode terminal tab that is integrally formed with one of the plurality of negative electrode bodies, and The positive electrode body and the negative electrode body are alternately stacked in the stacking direction, the positive electrode body on which the positive electrode terminal tab is formed and the negative electrode body on which the negative electrode terminal tab is formed are arranged on the outermost side, the first insulating tape is attached to the positive electrode body arranged on the outermost side, which covers the positive electrode body through the separator and maintains the stacked state of the positive electrode body, the second insulating tape is attached to the negative electrode body arranged on the outermost side, which covers the negative electrode body through the separator and maintains the stacked state of the negative electrode body, and the positive electrode connection piece that connects the positive electrode body arranged on the outermost side and the positive electrode body arranged one layer inside the negative electrode body arranged on the outermost side is attached with an extension tape portion arranged to cover through the separator.

The laminated electrode body according to the present invention can maintain the laminated state of the positive electrode body and the negative electrode body arranged on the outermost side by adhering the first insulating tape and the second insulating tape, so that the positive electrode and the negative electrode can be prevented from unwinding. This ensures the operational reliability of the electrochemical cell and makes it easy to incorporate the laminated electrode body into the exterior body.

In particular, the extension tape portion can be used to further cover the side surface of the laminated electrode body. Specifically, the extension tape portion can be used to cover, via the separator, a positive electrode connection piece that connects the outermost positive electrode main body on which the positive electrode terminal tab is formed and the positive electrode main body that is disposed one layer further inward than the outermost negative electrode main body on which the negative electrode terminal tab is formed.
As a result, even if a part of the negative electrode terminal tab is disposed outside the positive electrode connection piece via the separator when the laminated electrode body is accommodated, the extension tape portion can be used to prevent the negative electrode terminal tab from directly contacting the separator. Therefore, the extension tape portion can be used to protect the area where the negative electrode terminal tab may come into contact. Therefore, even if needle-shaped lithium metal is deposited on the negative electrode terminal tab during charging, for example, the extension tape portion can be used to prevent the lithium metal from penetrating the separator. Therefore, the possibility of an internal short circuit can be reduced. This leads to the realization of an electrochemical cell with improved safety.

(2) The positive electrode connection piece that connects the positive electrode body arranged on the outermost side to the positive electrode body arranged one layer inside the negative electrode body arranged on the outermost side may have the extension tape portion attached so as to cover the entire surface via the separator.

In this case, the above-mentioned effects can be achieved even more effectively, making it possible to produce a laminated electrode body in which internal short circuits are even less likely to occur.

(3) The positive electrode bodies are arranged along a first direction in an unfolded state, and the positive electrode terminal tab is formed on a positive electrode body located at one end position in the first direction among the positive electrode bodies, and the negative electrode bodies are arranged along the first direction in an unfolded state, and the negative electrode terminal tab is formed on a negative electrode body located at one end position in the first direction among the negative electrode bodies, and the positive electrode and the negative electrode stacked along the first direction may be repeatedly wound in the same direction.

In this case, the stacked electrode body can be constructed by repeatedly winding the positive electrode and the negative electrode in the same direction, so that the stacked electrode body can be constructed efficiently. This leads to improved manufacturing efficiency of the electrochemical cell itself. In addition, since the positive electrode and the negative electrode are wound in the same direction, it is easy to attach the first insulating tape and the second insulating tape including the extension tape portion.
Furthermore, since the positive and negative electrodes are wound to form a laminated electrode body, the laminated electrode body can be packed densely inside the exterior body in a state where it is wound in a flat shape without any protrusions. This allows for improved freedom in shape and improves the volume ratio of the laminated electrode body to the entire volume of the electrochemical cell. This can lead to the realization of a laminate-type electrochemical cell with improved volumetric efficiency, for example.

The present invention provides a laminated electrode body that can reduce the possibility of an internal short circuit caused by the negative electrode terminal tab.

1 is a perspective view showing an embodiment of a secondary battery (electrochemical cell) including a laminated electrode body according to the present invention. 2 is a longitudinal sectional view of the secondary battery taken along line AA shown in FIG. 1. 3 is an enlarged longitudinal sectional view of the secondary battery of a portion surrounded by a virtual circle B shown in FIG. 2. FIG. 3 is an exploded perspective view of the secondary battery shown in FIG. 2 . 5 is a longitudinal sectional view of the electrode body taken along line CC shown in FIG. 4. FIG. 6 is an enlarged cross-sectional view of a portion surrounded by an imaginary frame D shown in FIG. 5 . FIG. 5 is a perspective view of the electrode assembly shown in FIG. 4 . 8 is a plan view of the electrode body as viewed from the direction of arrow E shown in FIG. 7 . FIG. 6 is a development view of the positive electrode shown in FIG. 5 before being wound. FIG. 6 is a development view of the negative electrode shown in FIG. 5 before being wound. FIG. 11 is a diagram showing a state in which the positive electrode and the negative electrode shown in FIGS. 9 and 10 are starting to be wound. FIG. 13 is a perspective view of a secondary battery showing a modified example of the present invention. 13 is a perspective view showing an example of an electrode body in the secondary battery shown in FIG. 12.

Hereinafter, an embodiment of a laminated electrode body according to the present invention will be described with reference to the drawings. In this embodiment, a lithium ion secondary battery (hereinafter simply referred to as a secondary battery), which is a type of non-aqueous electrolyte secondary battery, will be used as an example of an electrochemical cell.

As shown in Figures 1 to 4, the secondary battery 1 of this embodiment is a so-called coin-type (button-type) battery, and mainly comprises an electrode body (laminated electrode body according to the present invention) 2 having multiple electrodes, i.e., positive electrodes 10 and negative electrodes 20, stacked on top of each other in the stacking direction, an insulating tape 4 (see Figures 7 and 8) attached to the electrode body 2, and an exterior body 3 formed of a laminate film and housing the electrode body 2 inside. Note that in each drawing, the electrode body 2 is illustrated in an appropriately simplified form.

As shown in Figures 4 to 6, the electrode body 2 includes a positive electrode 10, a negative electrode 20, and a separator 30. The electrode body 2 is a so-called laminated electrode in which the positive electrode 10 and the negative electrode 20 are stacked and wound flat with the separator 30 interposed therebetween. Note that the separator 30 is not shown in Figures 4 and 5.

In this embodiment, an example will be described in which the stacking direction Z is the vertical direction, that is, the positive electrode 10 and the negative electrode 20 are stacked in the vertical direction. Furthermore, an axis that passes through the center of the electrode body 2 and extends along the stacking direction Z is called the central axis O, and in a plan view seen from the direction of the central axis O, a direction that intersects with the central axis O is called the radial direction, and a direction going around the central axis O is called the circumferential direction.

7 and 8, the electrode body 2 is formed so that its outer shape is circular in plan view. However, the outer shape of the electrode body 2 is not limited to this case and may be other shapes, such as an ellipse, an oval shape, or a diamond shape, and may be changed as appropriate.
7 and 8, the thickness of the separator 30 is ignored and the separator 30 is hatched. Furthermore, in FIG. 7, the electrode assembly 2 is shown as viewed from the negative electrode 20 side.

The structure of the electrode body 2 will now be briefly described.
As shown in FIG. 9 , the positive electrode 10 includes a positive electrode collector 11 formed in a band shape extending along a first direction L1 in an unfolded state before being wound, and a positive electrode active material layer (not shown) formed on both sides of the positive electrode collector 11.

The positive electrode current collector 11 is formed in a thin sheet shape from a metal material such as aluminum or stainless steel, and includes a plurality of positive electrode bodies 12 and a plurality of positive electrode connection pieces 13. The positive electrode bodies 12 are formed in a disk shape and are arranged at intervals so as to be aligned in a line in the first direction L1. In the illustrated example, the number of positive electrode bodies 12 is eight. However, the number of positive electrode bodies 12 is not limited to eight and may be changed as appropriate.

The positive electrode connection pieces 13 are disposed between adjacent positive electrode bodies 12 in the first direction L1, and connect the adjacent positive electrode bodies 12 to each other. Therefore, in the illustrated example, the number of positive electrode connection pieces 13 is seven. Note that the width of the positive electrode connection pieces 13 in the second direction L2 perpendicular to the first direction L1 in a plan view is formed to be shorter than the width of the positive electrode bodies 12 in the second direction L2.

Of the multiple positive electrode bodies 12, the positive electrode body 12 located at one end position in the first direction L1 has a positive electrode terminal tab 14 formed thereon so as to extend further outward in the first direction L1.
In this embodiment, the positive electrode body 12 located at the other end position in the first direction L1 is referred to as the first tier positive electrode body 12, and the positive electrode bodies 12 on the other tiers are referred to as the second tier, third tier, fourth tier, fifth tier, sixth tier, seventh tier, and eighth tier positive electrode bodies 12 in that order toward the positive electrode body 12 on which the positive electrode terminal tab 14 is formed. Therefore, the positive electrode body 12 on which the positive electrode terminal tab 14 is formed corresponds to the eighth tier positive electrode body 12.

The positive electrode active material layer is formed on both sides of the positive electrode current collector 11 except for the positive electrode terminal tab 14. The positive electrode active material layer contains a positive electrode active material, a conductive assistant, a binder, a thickener, and the like, and is formed of a composite metal oxide such as lithium cobalt oxide or lithium nickel oxide.
Examples of the conductive assistant include carbon blacks, carbon materials, and metal fine powders. Examples of the binder include resin materials such as polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and polytetrafluoroethylene (PTFE). Examples of the thickener include resin materials such as carboxymethyl cellulose (CMC).

As shown in FIG. 10 , the negative electrode 20 includes a negative electrode current collector 21 formed in a band shape extending along a first direction L1 in an unfolded state before being wound, and a negative electrode active material layer (not shown) formed on both sides of the negative electrode current collector 21.
The negative electrode current collector 21 is formed in a thin sheet shape using a metal material such as copper, nickel, or stainless steel, and includes a plurality of negative electrode bodies 22 and a plurality of negative electrode connection pieces 23. The negative electrode bodies 22 are formed in a disk shape similar to the positive electrode bodies 12, and are arranged at intervals so as to be aligned in a line in the first direction L1. In the illustrated example, the number of negative electrode bodies 22 is eight, corresponding to the number of positive electrode bodies 12. However, the number of negative electrode bodies 22 is not limited to eight, and may be changed appropriately in accordance with the number of positive electrode bodies 12.

The negative electrode connection pieces 23 are disposed between the negative electrode bodies 22 adjacent to each other in the first direction L1, and connect the adjacent negative electrode bodies 22 to each other. Therefore, in the illustrated example, the number of negative electrode connection pieces 23 is seven. Note that the width of the negative electrode connection pieces 23 in the second direction L2 perpendicular to the first direction L1 in a plan view is formed to be shorter than the width of the negative electrode bodies 22 in the second direction L2.

Of the multiple negative electrode bodies 22, the negative electrode body 22 located at one end position in the first direction L1 has a negative electrode terminal tab 24 formed thereon so as to extend further outward in the first direction L1.
In this embodiment, the negative electrode body 22 located at the other end position in the first direction L1 is referred to as the first tier negative electrode body 22, and the negative electrode bodies 22 in the order from the first tier to the negative electrode body 22 on which the negative electrode terminal tab 24 is formed are referred to as the second tier, third tier, fourth tier, fifth tier, sixth tier, seventh tier, and eighth tier negative electrode body 22. Therefore, the negative electrode body 22 on which the negative electrode terminal tab 24 is formed corresponds to the eighth tier negative electrode body 22.

The negative electrode 20 configured as described above has an external shape similar to that of the positive electrode 10 described above. However, the external size of the positive electrode 10 is slightly smaller (one size smaller) than the external size of the negative electrode 20.

The negative electrode active material layer is formed on both sides of the negative electrode current collector 21 except for the negative electrode terminal tab 24. The negative electrode active material layer contains a negative electrode active material, a conductive assistant, a binder, a thickener, and the like, and is formed of a carbon material such as graphite.
Examples of the conductive assistant include carbon blacks, carbon materials, and metal fine powders. Examples of the binder include resin materials such as polyvinylidene fluoride (PVDF), styrene butadiene rubber (SBR), and polytetrafluoroethylene (PTFE). Examples of the thickener include resin materials such as carboxymethyl cellulose (CMC).

The positive electrode 10 and the negative electrode 20 configured as described above are wound with the separator 30 therebetween, as described above, so that they are stacked alternately.
Specifically, as shown in Fig. 11, the positive electrode 10 and the negative electrode 20 are arranged along the first direction L1 so that the positive terminal tab 14 and the negative terminal tab 24 are arranged on opposite sides to each other, and the first-stage positive electrode body 12 and the first-stage negative electrode body 22 are overlapped. Next, the positive electrode 10 and the negative electrode 20 are repeatedly wound in the same direction, starting from the overlapped first-stage positive electrode body 12 and negative electrode body 22. This allows the positive electrode bodies 12 and the negative electrode bodies 22 to be stacked alternately in the stacking direction Z, resulting in the electrode body 2 shown in Figs. 4 and 7.

The positive electrode terminal tab 14 and the negative electrode terminal tab 24 only need to be arranged in the opposite direction when the positive electrode 10 and the negative electrode 20 are wound to form the electrode body 2, and do not necessarily need to be arranged in the opposite direction at the start of winding (winding start stage) as described above. For example, the positive electrode terminal tab 14 and the negative electrode terminal tab 24 may be facing in the same direction, and then the positive electrode 10 and the negative electrode 20 may be overlapped, and winding may begin.

As shown in FIG. 6, the separator 30 is disposed between the layers of the positive electrode 10 and the negative electrode 20, and insulates the positive electrode 10 from the negative electrode 20. Therefore, the separator 30 is disposed so as to be interposed between the positive electrode 10 and the negative electrode 20 at least in the entire area where the positive electrode 10 and the negative electrode 20 face each other.

4 and 5, the electrode body 2 obtained by the above-mentioned winding has the eighth stage positive electrode main body 12 on which the positive electrode terminal tab 14 is formed located in the uppermost stage, and the eighth stage negative electrode main body 22 on which the negative electrode terminal tab 24 is formed located in the lowermost stage. Therefore, the electrode body 2 is accommodated at high density in the exterior body 3 with the positive electrode terminal tab 14 facing upward and the negative electrode terminal tab 24 facing downward.
The positive electrode terminal tab 14 is accommodated in a folded state with the connection portion with the eighth-stage positive electrode main body 12 as the base point. Similarly, the negative electrode terminal tab 24 is accommodated in a folded state with the connection portion with the eighth-stage negative electrode main body 22 as the base point.

In the electrode body 2 shown in FIG. 5, when the positive electrode 10 is focused on, the positive electrode 10 is wound so that the positive electrode bodies 12 are arranged parallel to each other in the stacking direction Z in the order of the eighth stage, the sixth stage, the fourth stage, the second stage, the first stage, the third stage, the fifth stage, and the seventh stage from top to bottom. In contrast, when the negative electrode 20 is focused on, the negative electrode 20 is wound so that the negative electrode bodies 22 are arranged parallel to each other in the stacking direction Z in the order of the seventh stage, the fifth stage, the third stage, the first stage, the second stage, the fourth stage, the sixth stage, and the eighth stage from top to bottom.

(Insulating tape)
As shown in Figures 7 and 8, the electrode body 2 includes a first insulating tape 40 that is attached so as to cover the eighth stage positive electrode body 12 arranged on the outermost side of the electrode body 2 via the separator 30, and maintains the wound state of the positive electrode body 12, and a second insulating tape 45 that is attached so as to cover the eighth stage negative electrode body 22 arranged on the outermost side via the separator 30, and maintains the wound state (stacked state) of the negative electrode body 22.

In addition, in Figures 7 and 8, the first insulating tape 40 and the second insulating tape 45 are illustrated by thick two-dot chain lines. In addition, in each drawing other than Figures 7 and 8, the first insulating tape 40 and the second insulating tape 45 are omitted as appropriate.

The first insulating tape 40 and the second insulating tape 45 can be, for example, a polyimide tape or a PET tape with a PET (polyethylene terephthalate) film base coated with an adhesive. However, the material of the first insulating tape 40 and the second insulating tape 45 is not limited to this case.

The first insulating tape 40 is also attached to the separator 30 located below the eighth-stage positive electrode body 12, straddling the outer edge of the eighth-stage positive electrode body 12. This makes it possible to maintain the wound state (stacked state) of the eighth-stage positive electrode body 12 by utilizing the first insulating tape 40, and to prevent the positive electrode 10 from unwinding.
Similarly, the second insulating tape 45 is also attached to the separator 30 located below the eighth-stage negative electrode body 22, straddling the outer edge of the eighth-stage negative electrode body 22. This makes it possible to maintain the wound state of the eighth-stage negative electrode body 22 by utilizing the second insulating tape 45, and to prevent the negative electrode 20 from unwinding.

The first insulating tape 40 further includes an extension tape portion 41 that is attached so as to completely cover the positive electrode connection piece 13 that connects the eighth-stage positive electrode body 12 located on the outermost side to the seventh-stage positive electrode body 12 located one layer inside the eighth-stage negative electrode body 22 located on the outermost side, via the separator 30.

As shown in Figures 1 to 4, the exterior body 3 is formed of a laminate film and includes a first laminate member 50 and a second laminate member 60 that are stacked in the stacking direction Z with the electrode body 2 sandwiched therebetween. As a result, the exterior body 3 contains the electrode body 2 in a sealed state between the first laminate member 50 and the second laminate member 60. An electrolyte solution (not shown) is filled between the first laminate member 50 and the second laminate member 60.

The first laminate member 50 is a member that covers the electrode body 2 from above, and has a metal layer 51, and an inner resin layer 52 and an outer resin layer 53 that cover both sides of the metal layer 51. The inner resin layer 52 and the outer resin layer 53 are tightly bonded to both sides of the metal layer 51, for example, by heat fusion or adhesion, via a bonding layer not shown. Note that the metal layer 51, the inner resin layer 52, and the outer resin layer 53 are not shown in Figures 1, 2, and 4.

The metal layer 51 is formed from a metal material suitable for blocking outside air and water vapor, such as stainless steel or aluminum.
The inner resin layer 52 functions as an inner layer in the exterior body 3, and is formed using a thermoplastic resin such as polyolefin polyethylene or polypropylene. As the polyolefin, any of the following materials can be used: high-pressure low-density polyethylene (LDPE), low-pressure high-density polyethylene (HDPE), inflation polypropylene (IPP) film, non-oriented polypropylene (CPP) film, biaxially oriented polypropylene (OPP) film, linear short-chain branched polyethylene (L-LDPE, metallocene catalyst type). In particular, polypropylene resin is preferable.
The outer resin layer 53 functions as an outer layer in the exterior body 3, and is formed using, for example, the above-mentioned polyolefin, polyester such as polyethylene terephthalate, nylon, or the like.

The first laminate member 50 includes a cylindrical storage portion 55 with a top and a first sealing cylindrical portion 58, and is disposed coaxially with the central axis O. The storage portion 55 includes a cylindrical peripheral wall portion 56 that surrounds the electrode body 2 from the outside in the radial direction, and a top wall portion 57 that closes the upper end opening of the peripheral wall portion 56 and covers the electrode body 2 from above.
The first sealing cylinder portion 58 is formed in a cylindrical shape that radially surrounds the peripheral wall portion 56 from the outside. The lower end portion of the first sealing cylinder portion 58 is formed to be integrally connected to the lower end portion of the peripheral wall portion 56. In other words, the first sealing cylinder portion 58 is formed by folding back the peripheral wall portion 56 upward.

The second laminate member 60 is a member that covers the electrode body 2 from below, and has a metal layer 61, and an inner resin layer 62 and an outer resin layer 63 that cover both sides of the metal layer 61. The inner resin layer 62 and the outer resin layer 63 are tightly joined to both sides of the metal layer 61, for example, by heat fusion or adhesion, via a joining layer (not shown).
The materials and the like of the metal layer 61, the inner resin layer 62, and the outer resin layer 63 are similar to those of the metal layer 51, the inner resin layer 52, and the outer resin layer 53 in the first laminate member 50. Moreover, the metal layer 61, the inner resin layer 62, and the outer resin layer 63 are omitted from illustration in Figures 1, 2, and 4.

The second laminate member 60 is formed in a bottomed cylindrical shape with a cylindrical second sealing tube portion 65 that further surrounds the first sealing tube portion 58 from the outside in the radial direction, and a bottom wall portion 66 that closes the lower end opening of the second sealing tube portion 65 and covers the electrode body 2 from below, and is arranged coaxially with the central axis O.

The first laminate member 50 and the second laminate member 60 configured as described above are combined in a state in which the electrode body 2 and the electrolyte solution are sealed inside by heat welding the first sealing tube portion 58 and the second sealing tube portion 65 to each other. Specifically, the inner resin layer 52 in the first sealing tube portion 58 and the inner resin layer 62 in the second sealing tube portion 65 are heat welded to each other.

Furthermore, as shown in Figures 2 and 4, the secondary battery 1 of this embodiment includes a first electrode plate 70 and a second electrode plate 71, a first electrode terminal plate 73 and a second electrode terminal plate 74, a first sealant film 75 and a second sealant film 76.
The first electrode plate 70 , the second electrode plate 71 , the first electrode terminal plate 73 , the second electrode terminal plate 74 , the first sealant film 75 and the second sealant film 76 are housed inside the exterior body 3 together with the electrode body 2 .

The first electrode plate 70, the first electrode terminal plate 73, and the first sealant film 75 are disposed between the electrode body 2 and the top wall portion 57 of the first laminate member 50. The second electrode plate 71, the second electrode terminal plate 74, and the second sealant film 76 are disposed between the electrode body 2 and the bottom wall portion 66 of the second laminate member 60.

The first electrode plate 70 is formed in a circular shape in a plan view, and is integrally connected to the positive electrode 10 of the electrode body 2. The first electrode plate 70 is made of a metal material such as aluminum or stainless steel, has a smaller diameter than the electrode body 2, and is disposed coaxially with the central axis O.
The first electrode plate 70 is disposed so as to overlap the eighth stage positive electrode body 12 of the positive electrode 10 in the electrode body 2, and the positive electrode terminal tab 14 is welded, for example, by ultrasonic welding, to the lower surface facing the electrode body 2. In this way, the first electrode plate 70 is integrally connected to the positive electrode 10.

The first electrode terminal plate 73 is made of a metal material such as nickel and has a circular shape in plan view with a smaller diameter than the first electrode plate 70, and is arranged so as to overlap the upper surface of the first electrode plate 70 facing the first laminate member 50. The first electrode terminal plate 73 is integrally fixed to the upper surface of the first electrode plate 70 by welding, for example, by resistance welding. The first electrode terminal plate 73 functions as an external connection terminal for the positive electrode 10.

A first through hole 57a is formed in the top wall portion 57 of the first laminate member 50, exposing the first electrode terminal plate 73 to the outside. The first through hole 57a is formed in a circular shape in a plan view so as to penetrate vertically through the center of the top wall portion 57, and is formed coaxially with the central axis O.

The first sealant film 75 is formed in a ring shape surrounding the first electrode terminal plate 73 from the radially outside, and is arranged coaxially with the central axis O between the first electrode terminal plate 73 and the top wall portion 57 of the first laminate member 50 while surrounding the first electrode terminal plate 73.
The first sealant film 75 is heat-welded to the inner resin layer 52 of the top wall portion 57 of the first laminate member 50 and to the upper surface of the first electrode plate 70. As a result, the first electrode plate 70 is heat-welded to the top wall portion 57 of the first laminate member 50 via the first sealant film 75.
The first sealant film 75 is formed of a thermoplastic resin, such as polyolefin polyethylene or polypropylene, or a nonwoven fabric made of polypropylene.

Since the first electrode plate 70, the first electrode terminal plate 73, and the first sealant film 75 are formed as described above, the entire surface of the first electrode terminal plate 73 is exposed upward through the first through hole 57a.

As shown in Figures 2 and 4, the second electrode plate 71, the second electrode terminal plate 74, and the second sealant film 76 are formed and arranged in the same manner as the first electrode plate 70, the first electrode terminal plate 73, and the first sealant film 75 described above.

The second electrode plate 71 is formed in a circular shape in a plan view, and is integrally connected to the negative electrode 20 in the electrode body 2. The second electrode plate 71 is formed with a smaller diameter than the electrode body 2 from a metal material such as copper, and is arranged coaxially with the central axis O. The second electrode plate 71 is arranged overlapping the negative electrode body 22 in the eighth stage of the negative electrode 20 in the electrode body 2, and the negative electrode terminal tab 24 is welded to the upper surface facing the electrode body 2, for example by ultrasonic welding. In this way, the second electrode plate 71 is integrally connected to the negative electrode 20.

The second electrode terminal plate 74 is made of a metal material such as nickel and has a circular shape in plan view with a smaller diameter than the second electrode plate 71, and is disposed on the underside of the second electrode plate 71 facing the second laminate member 60. The second electrode terminal plate 74 is integrally fixed to the underside of the second electrode plate 71 by welding such as resistance welding. The second electrode terminal plate 74 functions as an external connection terminal for the negative electrode.

A second through hole 66a is formed in the bottom wall portion 66 of the second laminate member 60, exposing the second electrode terminal plate 74 to the outside. The second through hole 66a is formed in a circular shape in a plan view so as to penetrate vertically through the center of the bottom wall portion 66, and is formed coaxially with the central axis O.

The second sealant film 76 is formed in a ring shape surrounding the second electrode terminal plate 74 from the radially outside, and is arranged coaxially with the central axis O between the second electrode terminal plate 74 and the bottom wall portion 66 of the second laminate member 60 while surrounding the second electrode terminal plate 74.
The second sealant film 76 is heat-welded to the inner resin layer 62 of the bottom wall portion 66 of the second laminate member 60 and to the lower surface of the second electrode plate 71. As a result, the second electrode plate 71 is heat-welded to the bottom wall portion 66 of the second laminate member 60 via the second sealant film 76.
Like the first sealant film 75, the second sealant film 76 is formed of a thermoplastic resin such as polyolefin polyethylene or polypropylene, or a nonwoven fabric made of polypropylene.

Since the second electrode plate 71, the second electrode terminal plate 74, and the second sealant film 76 are formed as described above, the entire surface of the second electrode terminal plate 74 is exposed downward through the second through hole 66a.

(Function of secondary battery)
According to the secondary battery 1 configured as described above, as shown in FIG. 2, the first electrode terminal plate 73 fixed to the first electrode plate 70 is exposed to the outside, and the second electrode terminal plate 74 fixed to the second electrode plate 71 is exposed to the outside, so that the first electrode terminal plate 73 and the second electrode terminal plate 74 can each function as an external connection terminal.
This makes it possible to use the secondary battery 1 by utilizing the first electrode terminal plate 73 and the second electrode terminal plate 74 .

In particular, according to the secondary battery 1 of this embodiment, the positive electrode 10 and the negative electrode 20 are wound to form the electrode body 2, so that the electrode body 2 can be packed densely inside the exterior body 3 in a state where it is wound in a flat shape without protrusions. This allows for improved freedom of shape, and also improves the volume ratio of the electrode body 2 to the entire volume of the secondary battery 1, resulting in a laminate-type secondary battery 1 with improved volumetric efficiency.

Furthermore, as shown in Figs. 7 and 8, the application of the first insulating tape 40 and the second insulating tape 45 maintains the wound state of the eighth layer of the positive electrode body 12 and the eighth layer of the negative electrode body 22 arranged on the outermost side, so that the positive electrode 10 and the negative electrode 20 can be prevented from unwinding. This ensures the operational reliability of the secondary battery 1, and makes it easy to install the electrode body 2 inside the exterior body 3.

In particular, as shown in FIG. 7, the extension tape portion 41 can be used to further cover the side portion of the laminated electrode body 2. Specifically, the extension tape portion 41 can be used to cover, via the separator 30, the positive electrode connection piece 13 that connects the positive electrode body 12 on the outermost side (eighth stage) where the positive electrode terminal tab 14 is formed and the positive electrode body 12 on the seventh stage that is arranged one stage inside the negative electrode body 22 on the outermost side (eighth stage) where the negative electrode terminal tab 24 is formed.

As a result, even if the negative electrode terminal tab 24 is bent in such a way that a part of the negative electrode terminal tab 24 is disposed outside the positive electrode connection piece 13 via the separator 30 when the electrode body 2 is housed, the extension tape portion 41 can be used to prevent the negative electrode terminal tab 24 from directly contacting the separator 30. Therefore, the extension tape portion 41 can be used to protect the area where the negative electrode terminal tab 24 may come into contact.

Therefore, even if needle-like lithium metal precipitates on the negative electrode terminal tab 24 during charging, the extension tape portion 41 can be used to prevent the lithium metal from penetrating the separator 30. This reduces the possibility of an internal short circuit, resulting in a secondary battery 1 with improved safety.

As described above, the secondary battery 1 of this embodiment can reduce the possibility of an internal short circuit caused by the negative electrode terminal tab 24, resulting in a laminate-type battery with improved safety.

Furthermore, since the electrode body 2 can be constructed by repeatedly winding the positive electrode 10 and the negative electrode 20 in the same direction, the electrode body 2 can be constructed efficiently, which leads to improved manufacturing efficiency of the secondary battery 1 itself. In addition, since the positive electrode 10 and the negative electrode 20 are wound in the same direction, it is easy to attach the first insulating tape 40 and the second insulating tape 45 including the extension tape portion 41 to the electrode body 2.

Although the embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. The embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. Examples of the embodiments and their variations include those that can be easily imagined by a person skilled in the art, those that are substantially the same, and those that are within the scope of equivalents.

For example, in the above embodiment, a secondary battery 1 is used as an example of an electrochemical cell, but the present invention is not limited to this case, and the electrochemical cell may be, for example, a capacitor (such as a lithium ion capacitor) or a primary battery.

Furthermore, in the above embodiment, the second electrode plate 71 is made of copper, but it may be made of nickel, for example. In this case, the second electrode terminal plate 74 may be omitted. In other words, an electrode terminal plate is not necessarily required for the negative electrode side, and may not be provided. In this case, the second electrode plate 71 itself can function as an external connection terminal for the negative electrode side.
Furthermore, the entire exterior body 3 does not need to be made of a laminate film, but it is sufficient that at least a portion of it is made of a laminate film.

In addition, in the above embodiment, the secondary battery 1 is circular in plan view, but the shape of the secondary battery 1 may be changed as appropriate. For example, as shown in FIG. 12, a secondary battery (electrochemical cell according to the present invention) 80 may be oval in plan view, with a combination of straight and semicircular portions. In this case, the shape of the electrode body 2 may be oval in plan view, as shown in FIG. 13, corresponding to the external shape of the secondary battery 80.

L1: first direction; Z: stacking direction; 1, 80: secondary battery (electrochemical cell)
2... Electrode body (laminated electrode body)
Reference Signs List 3: Exterior body 4: Insulating tape 10: Positive electrode 12: Positive electrode body 13: Positive electrode connection piece 14: Positive electrode terminal tab 20: Negative electrode 22: Negative electrode body 23: Negative electrode connection piece 24: Negative electrode terminal tab 40: First insulating tape 41: Extension tape portion 45: Second insulating tape

Claims (3)

A laminated electrode assembly to be housed inside an exterior body of an electrochemical cell and to which an insulating tape including a first insulating tape and a second insulating tape having an extension tape portion is attached,
A positive electrode;
A negative electrode is laminated on the positive electrode via a separator,
The positive electrode includes a plurality of positive electrode bodies arranged along a stacking direction of the laminated electrode body, a positive electrode connection piece connecting the plurality of positive electrode bodies to each other, and a positive electrode terminal tab formed integrally with one of the plurality of positive electrode bodies,
the negative electrode includes a plurality of negative electrode bodies arranged along a stacking direction of the laminated electrode body, a negative electrode connection piece connecting the plurality of negative electrode bodies to each other, and a negative electrode terminal tab formed integrally with one of the plurality of negative electrode bodies,
The positive electrode body and the negative electrode body are alternately stacked in the stacking direction,
The positive electrode main body on which the positive electrode terminal tab is formed and the negative electrode main body on which the negative electrode terminal tab is formed are disposed on the outermost peripheral side,
The positive electrode body arranged on the outermost peripheral side is covered with the separator and the first insulating tape is attached to maintain the stacked state of the positive electrode body,
The negative electrode body arranged on the outermost peripheral side is covered with the separator and the second insulating tape is attached to maintain the stacked state of the negative electrode body,
A laminated electrode body, characterized in that an extension tape portion is attached to the positive electrode connection piece, which connects the positive electrode main body arranged on the outermost side and the positive electrode main body arranged one layer inside the negative electrode main body arranged on the outermost side, so as to cover the separator. The laminated electrode body according to claim 1 ,
a positive electrode connecting piece that connects the positive electrode main body arranged on the outermost side and the positive electrode main body arranged one layer inside the negative electrode main body arranged on the outermost side, the extension tape portion being arranged so as to cover the entire surface via the separator, said laminated electrode body. The laminated electrode body according to claim 1 or 2,
The positive electrode bodies are arranged along a first direction in an expanded state,
The positive electrode terminal tab is formed on a positive electrode body located at one end position in the first direction among the plurality of positive electrode bodies,
The negative electrode bodies are arranged along the first direction in an expanded state,
The negative electrode terminal tab is formed on a negative electrode body located at one end position in the first direction among the plurality of negative electrode bodies,
The positive electrode and the negative electrode stacked along the first direction are repeatedly wound in the same direction.

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