JP2021061161A - Electrochemical cell - Google Patents

Abstract

To provide a lamination type electrochemical cell that can reduce the possibility of internal short circuit caused by a negative electrode terminal tab and has improved safety.SOLUTION: An electrochemical cell 1 includes a laminated electrode body 2 having a positive electrode 10 and a negative electrode 20 which are laminated via a separator 30, an insulating tape 4 attached to the laminated electrode body, and an exterior package body for accommodating the laminated electrode body therein. The insulating tape includes a first insulating tape 40 which is attached so as to cover the positive electrode body 12 arranged on the outermost peripheral side through a separator, and a second insulating tape 45 which is attached so as to cover the negative electrode body 22 arranged on the outermost peripheral side through a separator. The first insulating tape includes an extension tape portion 41 which is attached so as to cover, through a separator, a positive electrode connecting piece 13 that connects the positive electrode body arranged on the outermost peripheral side and the positive electrode body arranged at one layer just inside the negative electrode body arranged on the outermost peripheral side.SELECTED DRAWING: Figure 7

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 power sources for small devices such as smartphones, wearable devices, and hearing aids.
In recent years, as this type of electrochemical cell, a so-called laminated type electrochemical cell in which a laminated film is used for an outer body accommodating an electrode body is known. This laminated type electrochemical cell is known as an electrochemical cell that is small in size, has a high degree of freedom in shape, and leads to a higher capacity.

For example, Patent Document 1 below includes an electrode body and an exterior body having a first laminated member and a second laminated member and accommodating the electrode body between the first laminated member and the second laminated member. Electrochemical cells are disclosed.
The electrode body has a structure including negative electrode electrodes and positive electrode electrodes that are alternately laminated via a separator. The negative electrode has a negative electrode terminal tab, and is connected to, for example, a copper plate that functions as an electrode plate on the negative electrode side. Similarly, the positive electrode has a positive electrode terminal tab, and is connected to, for example, an aluminum plate that functions as an electrode plate on the positive electrode side.

JP-A-2018-85214

In the conventional laminated type electrochemical cell, the outer shape of the negative electrode is generally 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 in which lithium ions that have moved from the positive electrode side to the negative electrode side are deposited as lithium metal on the surface of the negative electrode during charging. In this case, for example, lithium metal may be concentrated on the edge of the negative electrode and deposited in a needle shape. Therefore, when the outer shape of the negative electrode is smaller than the outer shape of the positive electrode, the needle-shaped deposited lithium metal penetrates the separator and reaches the positive electrode, which may cause an internal short circuit.
Therefore, in order to suppress the occurrence of such an internal short circuit, the outer shape of the negative electrode is often formed larger than the outer shape of the positive electrode.

By the way, even when the outer shape of the negative electrode is larger than the outer shape of the positive electrode, the electrode body is accommodated in a state where the negative electrode terminal tabs are arranged to face the positive electrode via the separator. It may be done.
Normally, the negative electrode terminal tab is folded back from its root side as a base point, and is connected to a copper plate or the like without being arranged facing the positive electrode electrode via a separator. However, for some reason, such as not being properly folded back, the negative electrode terminal tab may be arranged to face the positive electrode electrode via the separator as described above. In this case, as in the case described above, there is a possibility that the lithium metal is deposited in a needle shape on the negative electrode terminal tab and penetrates the separator to reach the positive electrode. Therefore, there is a risk of causing an internal short circuit, and there is room for improvement.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a laminated type electrochemical cell in which the possibility of an internal short circuit due to a negative electrode terminal tab can be reduced and safety is improved. It is to be.

(1) The electrochemical cell according to the present invention is formed of a laminated electrode body having a positive electrode and a negative electrode superimposed on each other via a separator, an insulating tape attached to the laminated electrode body, and a laminated film. A plurality of positive electrode bodies arranged along the stacking direction of the laminated electrode bodies, and the plurality of positive electrode bodies are connected to each other. A positive electrode connection piece and a positive electrode terminal tab integrally formed with one of the plurality of positive electrode bodies are provided, and the negative electrode is provided with a plurality of negative electrode bodies arranged along the stacking direction of the laminated electrode bodies. The laminated electrode body includes the negative electrode connecting piece for connecting the plurality of the negative electrode bodies and the negative electrode terminal tab integrally formed with one of the plurality of negative electrode bodies, and the laminated electrode body includes the positive electrode body and the negative electrode body. Are alternately laminated in the stacking direction, and 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 formed so as to be arranged on the outermost peripheral side. The insulating tape was attached to the positive electrode body arranged on the outermost peripheral side so as to cover the positive electrode body via the separator, and was arranged on the outermost peripheral side with the first insulating tape for maintaining the laminated state of the positive electrode body. The negative electrode body is attached so as to cover the negative electrode body via the separator, and includes a second insulating tape that maintains the laminated state of the negative electrode body, and the first insulating tape is arranged on the outermost peripheral side. An extension tape portion is attached so as to cover the positive electrode connection piece that connects the positive electrode body and the positive electrode body arranged one layer inside the negative electrode body arranged on the outermost peripheral side with the separator. It is characterized by having.

According to the electrochemical cell according to the present invention, the positive electrode main body and the negative electrode main body arranged on the outermost peripheral side can be maintained in a laminated state by attaching the first insulating tape and the second insulating tape. And the unwinding of the negative electrode can be prevented. Therefore, the operational reliability of the electrochemical cell can be ensured, and the work of incorporating the laminated electrode body into the exterior body can be easily performed.

In particular, the extension tape portion can be used to further cover the side surface portion of the laminated electrode body. Specifically, using the extension tape portion, the positive electrode main body on the outermost peripheral side where the positive electrode terminal tab was formed and the negative electrode main body on the outermost peripheral side where the negative electrode terminal tab was formed were arranged one layer inside. The positive electrode connection piece connecting the positive electrode body can be covered with a separator.
As a result, even if a part of the negative electrode terminal tab is arranged outside the positive electrode connection piece via the separator when the laminated electrode body is accommodated, the negative electrode portion is used to utilize the negative electrode portion. It is possible to prevent the terminal tab from coming into direct contact with the separator. Therefore, the area where the negative electrode terminal tabs may come into contact can be protected by using the extension tape portion. Therefore, for example, even if the lithium metal is deposited in the shape of a needle on the negative electrode terminal tab during charging, it is possible to prevent the lithium metal from penetrating the separator by using the extension tape portion. Therefore, the possibility of an internal short circuit can be reduced, and the electrochemical cell with improved safety can be obtained.

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

In this case, the above-mentioned action and effect can be more effectively achieved, and an electrochemical cell in which an internal short circuit is less likely to occur can be obtained.

(3) The plurality of positive electrode bodies are arranged along the first direction in the expanded state, and the positive electrode terminal tab is a positive electrode located at one end position in the first direction among the plurality of positive electrode bodies. The plurality of the negative electrode bodies formed on the main body are arranged along the first direction in the deployed state, and the negative electrode terminal tab is located at one end position of the plurality of the negative electrode bodies in the first direction. The laminated electrode body, which is formed on the position negative electrode body, may be formed by repeatedly winding the positive electrode and the negative electrode which are overlapped along the first direction in the same direction.

In this case, since the laminated electrode body can be constructed by repeatedly winding the positive electrode and the negative electrode in the same direction, the laminated electrode body can be efficiently constructed, and the manufacturing efficiency of the electrochemical cell itself is improved. It can be connected to the conversion. Further, 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.
Further, since the positive electrode and the negative electrode are wound to form a laminated electrode body, for example, the laminated electrode body can be accommodated in a high density inside the exterior body in a state of being wound in a flat shape without a protrusion. it can. Therefore, it is possible to improve the degree of freedom in shape, improve the volume ratio of the laminated electrode body to the volume of the entire electrochemical cell, and make the laminated type electrochemical cell with improved volumetric efficiency. Can be done.

According to the present invention, the possibility of an internal short circuit due to the negative electrode terminal tab can be reduced, and a laminated type electrochemical cell with improved safety can be obtained.

It is a perspective view which shows the embodiment of the secondary battery (electrochemical cell) which concerns on this invention. It is a vertical sectional view of the secondary battery along the line AA shown in FIG. It is a vertical sectional view of the secondary battery which enlarged the part surrounded by the virtual circle B shown in FIG. It is an exploded perspective view of the secondary battery shown in FIG. It is a vertical cross-sectional view of the electrode body along the line CC shown in FIG. FIG. 5 is an enlarged cross-sectional view of a portion surrounded by the virtual frame D shown in FIG. It is a perspective view of the electrode body shown in FIG. It is a top view of the electrode body seen from the direction of arrow E shown in FIG. FIG. 5 is a development view of the positive electrode shown in FIG. 5 before winding. FIG. 5 is a development view of the negative electrode shown in FIG. 5 before winding. 9 is a diagram showing a state in which the positive electrode and the negative electrode shown in FIGS. 9 and 10 have begun to be wound. It is a figure which shows the modification which concerns on this invention, and is the perspective view of the secondary battery. It is a perspective view which shows an example of the electrode body in the secondary battery shown in FIG.

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

As shown in FIGS. 1 to 4, the secondary battery 1 of the present embodiment is a so-called coin-type (button-type) battery, and a plurality of electrodes laminated to each other in the stacking direction, that is, a positive electrode 10 and a negative electrode. It is formed of an electrode body (laminated electrode body according to the present invention) 2 having 20 and an insulating tape 4 (see FIGS. 7 and 8) attached to the electrode body 2 and a laminated film, and the electrode body 2 is inside. It mainly includes an exterior body 3 for accommodating the exterior body 3. In each drawing, the electrode body 2 is shown in a simplified manner as appropriate.

As shown in FIGS. 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 a positive electrode 10 and a negative electrode 20 are overlapped with each other via a separator 30 and wound flat. Note that the separator 30 is not shown in FIGS. 4 and 5.

In the present embodiment, a case where the positive electrode 10 and the negative electrode 20 are laminated in the vertical direction so that the stacking direction Z is in the vertical direction will be described as an example. Further, the axis extending through the center of the electrode body 2 and along the stacking direction Z is called the central axis O, and the direction intersecting the central axis O in the plan view from the central axis O direction is the radial direction and the central axis O circumference. The direction of orbiting is called the circumferential direction.

As shown in FIGS. 7 and 8, the electrode body 2 is formed so as to have a circular outer shape in a plan view. However, the outer shape of the electrode body 2 is not limited to this case, and may be another shape such as an elliptical shape, an oval shape, a diamond shape, or the like, and may be changed as appropriate.
In addition, in FIG. 7 and FIG. 8, the thickness of the separator 30 is ignored and is shown by hatching. Further, FIG. 7 shows the electrode body 2 seen from the negative electrode electrode 20 side.

The structure of the electrode body 2 will be briefly described.
As shown in FIG. 9, the positive electrode electrodes 10 are formed on both sides of the positive electrode current collector 11 formed in a band shape extending along the first direction L1 in the unfolded state before winding and the positive electrode current collector 11. It is provided with a positive electrode active material layer (not shown).

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

The positive electrode connection piece 13 is arranged between the positive electrode main bodies 12 adjacent to the first direction L1 and connects the adjacent positive electrode main bodies 12 to each other. Therefore, in the illustrated example, the number of the positive electrode connection pieces 13 is seven. The positive electrode connection piece 13 is formed so that the width along the second direction L2 orthogonal to the first direction L1 in a plan view is shorter than the width along the second direction L2 of the positive electrode main body 12.

A positive electrode terminal tab 14 is formed on the positive electrode main body 12 located at one end position in the first direction L1 among the plurality of positive electrode main bodies 12 so as to extend further toward the outside of the first direction L1. ..
In the present embodiment, the positive electrode body 12 located at the other end position in the first direction L1 is referred to as the first-stage positive electrode body 12, and is directed toward the positive electrode body 12 on which the positive electrode terminal tab 14 is formed. These are referred to as the second-stage, third-stage, fourth-stage, fifth-stage, sixth-stage, seventh-stage, and eighth-stage positive electrode body 12 in this order. Therefore, the positive electrode main body 12 on which the positive electrode terminal tab 14 is formed corresponds to the positive electrode main body 12 in the eighth stage.

The positive electrode active material layer is formed on both sides of the positive electrode current collector 11 excluding the positive electrode terminal tab 14. The positive electrode active material layer contains a positive electrode active material, a conductive auxiliary agent, a binder, a thickener, and the like, and is formed of a composite metal oxide such as lithium cobalt oxide and lithium nickel oxide.
Examples of the conductive auxiliary agent include carbon blacks, carbon materials, and fine metal 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 a resin material such as carboxymethyl cellulose (CMC).

As shown in FIG. 10, the negative electrode electrodes 20 are formed on both sides of the negative electrode current collector 21 formed in a band shape extending along the first direction L1 in the unfolded state before winding and the negative electrode current collector 21. It is provided with a negative electrode active material layer (not shown).
The negative electrode current collector 21 is formed of a metal material such as copper, nickel, and stainless steel in the form of a thin sheet, and includes a plurality of negative electrode main bodies 22 and a plurality of negative electrode connecting pieces 23. The negative electrode main body 22 is formed in a disk shape like the positive electrode main body 12, and is arranged at intervals so as to be lined up in a row in the first direction L1. In the illustrated example, the number of the negative electrode main body 22 is 8 corresponding to the number of the positive electrode main body 12. However, the number of the negative electrode main body 22 is not limited to eight, and may be appropriately changed according to the number of the positive electrode main body 12.

The negative electrode connection piece 23 is arranged between the negative electrode main bodies 22 adjacent to the first direction L1 and connects the adjacent negative electrode main bodies 22 to each other. Therefore, in the illustrated example, the number of the negative electrode connection pieces 23 is seven. The negative electrode connection piece 23 is formed so that the width along the second direction L2 orthogonal to the first direction L1 in a plan view is shorter than the width along the second direction L2 of the negative electrode main body 22.

Of the plurality of negative electrode bodies 22, the negative electrode body 22 located at one end position in the first direction L1 is formed with a negative electrode terminal tab 24 so as to extend further toward the outside of the first direction L1. ..
In the present embodiment, the negative electrode body 22 located at the other end position in the first direction L1 is referred to as the first-stage negative electrode body 22, and is directed toward the negative electrode body 22 on which the negative electrode terminal tab 24 is formed. These are referred to as the second-stage, third-stage, fourth-stage, fifth-stage, sixth-stage, seventh-stage, and eighth-stage negative electrode main body 22 in this order. Therefore, the negative electrode main body 22 on which the negative electrode terminal tab 24 is formed corresponds to the negative electrode main body 22 in the eighth stage.

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

The negative electrode active material layer is formed on both sides of the negative electrode current collector 21 excluding the negative electrode terminal tab 24. The negative electrode active material layer contains a negative electrode active material, a conductive auxiliary agent, a binder, a thickener and the like, and is formed of a carbon material such as graphite.
Examples of the conductive auxiliary agent include carbon blacks, carbon materials, and fine metal 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 a resin material such as carboxymethyl cellulose (CMC).

The positive electrode 10 and the negative electrode 20 configured as described above are alternately laminated by being wound around the separator 30 as described above.
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 electrode terminal tab 14 and the negative electrode terminal tab 24 are arranged on opposite sides of each other. 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 first-stage positive electrode body 12 and the negative electrode body 22 that are overlapped with each other. As a result, the positive electrode main body 12 and the negative electrode main body 22 can be laminated in the stacking direction Z so as to be alternately overlapped with each other, and the electrode body 2 shown in FIGS. 4 and 7 can be obtained.

The positive electrode terminal tab 14 and the negative electrode terminal tab 24 need only be arranged in opposite directions when the positive electrode electrode 10 and the negative electrode electrode 20 are wound to form the electrode body 2, and are wound as described above. It is not always necessary that they are arranged in opposite directions at the initial stage (turning start stage). For example, winding may be started after the positive electrode 10 and the negative electrode 20 are overlapped with the positive electrode terminal tab 14 and the negative electrode terminal tab 24 facing in the same direction.

As shown in FIG. 6, the separator 30 is arranged between the positive electrode 10 and the negative electrode 20 to insulate the positive electrode 10 and the negative electrode 20. Therefore, the separator 30 is arranged so as to be interposed between the positive electrode 10 and the negative electrode 20 in at least the entire region where the positive electrode 10 and the negative electrode 20 face each other.

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

In the electrode body 2 shown in FIG. 5, focusing on the positive electrode 10, the 8th stage, the 6th stage, the 4th stage, the 2nd stage, the 1st stage, and the 1st stage are directed from the upper side to the lower side. 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 third stage, the fifth stage, and the seventh stage. On the other hand, focusing on the negative electrode 20, from the top to the bottom, the 7th stage, the 5th stage, the 3rd stage, the 1st stage, the 2nd stage, the 4th stage, and the 6th stage. The negative electrode 20 is wound so that the negative electrode main body 22 is arranged parallel to each other in the stacking direction Z in the order of the first stage and the eighth stage.

(Insulating tape)
As shown in FIGS. 7 and 8, the eighth-stage positive electrode body 12 arranged on the outermost peripheral side of the electrode body 2 is attached so as to cover it via the separator 30, and the positive electrode body 12 is wound. The first insulating tape 40 that maintains the state and the eighth-stage negative electrode body 22 arranged on the outermost peripheral side are attached so as to cover the negative electrode body 22 via the separator 30, and the negative electrode body 22 is wound (laminated state). ) Is provided with a second insulating tape 45.

In addition, in FIG. 7 and FIG. 8, the first insulating tape 40 and the second insulating tape 45 are illustrated by a thick two-dot chain line. Further, in the drawings other than those shown in FIGS. 7 and 8, the first insulating tape 40 and the second insulating tape 45 are not shown as appropriate.

As the first insulating tape 40 and the second insulating tape 45, for example, a polyimide tape, a PET tape in which an adhesive is applied to a PET (polyethylene terephthalate) film base material, or the like can be adopted. However, the materials of the first insulating tape 40 and the second insulating tape 45 are not limited to this case.

The first insulating tape 40 is also attached to the separator 30 located in the lower layer of the eighth-stage positive electrode body 12 in a state of straddling the outer edge of the eighth-stage positive electrode body 12. As a result, the first insulating tape 40 can be used to maintain the wound state (laminated state) of the positive electrode body 12 in the eighth stage, and the unwinding of the positive electrode electrode 10 can be prevented. There is.
Similarly, the second insulating tape 45 is also attached to the separator 30 located in the lower layer of the eighth-stage negative electrode main body 22 while straddling the outer edge portion of the eighth-stage negative electrode main body 22. As a result, the second insulating tape 45 can be used to maintain the wound state of the negative electrode main body 22 in the eighth stage, and the negative electrode 20 can be prevented from unwinding.

Further, the first insulating tape 40 has seven stages arranged one layer inside the eighth-stage positive electrode main body 12 arranged on the outermost peripheral side and the eighth-stage negative electrode main body 22 arranged on the outermost outer peripheral side. An extension tape portion 41 is provided so as to cover the entire surface of the positive electrode connecting piece 13 connecting the positive electrode body 12 of the eye with the separator 30.

As shown in FIGS. 1 to 4, the exterior body 3 includes a first laminated member 50 and a second laminated member 60 formed of a laminated film and laminated in the stacking direction Z with the electrode body 2 sandwiched between them. There is. As a result, the exterior body 3 accommodates the electrode body 2 in a sealed state between the first laminated member 50 and the second laminated member 60. An electrolyte solution (not shown) is filled between the first laminating member 50 and the second laminating member 60.

The first laminated 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 densely bonded to both surfaces of the metal layer 51 via a bonding layer (not shown), for example, by heat fusion or adhesion. Note that in FIGS. 1, 2 and 4, the metal layer 51, the inner resin layer 52 and the outer resin layer 53 are not shown.

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

The first laminating member 50 includes a ridged tubular accommodating portion 55 and a first sealing tubular portion 58, and is arranged coaxially with the central axis O. The accommodating portion 55 includes a tubular 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 tubular shape that surrounds the peripheral wall portion 56 from the outside in the radial direction. The lower end of the first sealing cylinder 58 is formed so as to be integrally connected to the lower end of the peripheral wall 56. That is, the first sealing cylinder portion 58 is formed by folding back the peripheral wall portion 56 upward.

The second laminating 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 overlap both surfaces of the metal layer 61. The inner resin layer 62 and the outer resin layer 63 are densely bonded to both surfaces of the metal layer 61 via a bonding layer (not shown), for example, by heat fusion or adhesion.
The materials of the metal layer 61, the inner resin layer 62, and the outer resin layer 63 are the same as those of the metal layer 51, the inner resin layer 52, and the outer resin layer 53 in the first laminating member 50. Further, in FIGS. 1, 2 and 4, the metal layer 61, the inner resin layer 62 and the outer resin layer 63 are not shown.

The second laminating member 60 closes the tubular second sealing cylinder portion 65 that further surrounds the first sealing cylinder portion 58 from the outside in the radial direction and the lower end opening of the second sealing cylinder portion 65, and also has electrodes. It is formed in a bottomed tubular shape including a bottom wall portion 66 that covers the body 2 from below, and is arranged coaxially with the central axis O.

In the first laminated member 50 and the second laminated member 60 configured as described above, the electrode body 2 and the electrolyte are formed by heat-welding the first sealing cylinder portion 58 and the second sealing cylinder portion 65 to each other. The solutions are combined in a sealed state. Specifically, the inner resin layer 52 in the first sealing cylinder portion 58 and the inner resin layer 62 in the second sealing cylinder portion 65 are heat-welded to each other.

Further, as shown in FIGS. 2 and 4, the secondary battery 1 of the present 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, and a second electrode plate 74. It includes one 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 formed inside the exterior body 3 together with the electrode body 2. It is contained.

The first electrode plate 70, the first electrode terminal plate 73, and the first sealant film 75 are arranged between the electrode body 2 and the top wall portion 57 of the first laminated member 50. The second electrode plate 71, the second electrode terminal plate 74, and the second sealant film 76 are arranged between the electrode body 2 and the bottom wall portion 66 of the second laminated 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 in the electrode body 2. The first electrode plate 70 is formed of a metal material such as aluminum or stainless steel with a diameter smaller than that of the electrode body 2, and is arranged coaxially with the central axis O.
The first electrode plate 70 is arranged so as to overlap the positive electrode main body 12 of the eighth stage of the positive electrode 10 in the electrode body 2, and the positive electrode terminal tab 14 is formed on the lower surface facing the electrode body 2 side, for example, by ultrasonic welding or the like. Welded by. As a result, the first electrode plate 70 is integrally connected to the positive electrode 10.

The first electrode terminal plate 73 is formed of a metal material such as nickel into a circular shape in a plan view having a diameter smaller than that of the first electrode plate 70, and the upper surface of the first electrode plate 70 facing the first laminated member 50 side. It is placed so that it overlaps with. The first electrode terminal plate 73 is integrally fixed to the upper surface of the first electrode plate 70 by, for example, welding by resistance welding or the like. The first electrode terminal plate 73 functions as an external connection terminal for the positive electrode 10.

The top wall portion 57 of the first laminated member 50 is formed with a first through hole 57a that exposes 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 vertically penetrate the central portion of the top wall portion 57, and is formed coaxially with the central axis O.

The first sealant film 75 is formed in an annular shape that surrounds the first electrode terminal plate 73 from the outside in the radial direction, and the top wall of the first electrode terminal plate 73 and the first laminated member 50 in a state of surrounding the first electrode terminal plate 73. It is arranged coaxially with the central axis O between the portion 57 and the central axis O.
The first sealant film 75 is heat-welded to the inner resin layer 52 of the top wall portion 57 of the first laminated member 50 and the upper surface of the first electrode plate 70, respectively. As a result, the first electrode plate 70 is heat-welded to the top wall portion 57 of the first laminated member 50 via the first sealant film 75.
The first sealant film 75 is made of, for example, a thermoplastic resin such as polyethylene or polypropylene of poreolefin, or a non-woven fabric made of polypropylene or the like.

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 FIGS. 2 and 4, the second electrode plate 71, the second electrode terminal plate 74, and the second sealant film 76 are the first electrode plate 70, the first electrode terminal plate 73, and the first sealant film 75 described above. Formed in the same way as, and arranged in the same way.

The second electrode plate 71 is formed in a circular shape in a plan view and is integrally connected to the negative electrode electrode 20 in the electrode body 2. The second electrode plate 71 is formed of a metal material such as copper and has a diameter smaller than that of the electrode body 2, and is arranged coaxially with the central axis O. The second electrode plate 71 is arranged so as to overlap the negative electrode main body 22 at the eighth stage of the negative electrode 20 in the electrode body 2, and the negative electrode terminal tab 24 is formed on the upper surface facing the electrode body 2 side, for example, by ultrasonic welding or the like. Welded by. As a result, the second electrode plate 71 is integrally connected to the negative electrode electrode 20.

The second electrode terminal plate 74 is formed of a metal material such as nickel into a circular shape in a plan view having a diameter smaller than that of the second electrode plate 71, and the lower surface of the second electrode plate 71 facing the second laminated member 60 side. It is placed on top. The second electrode terminal plate 74 is integrally fixed to the lower surface of the second electrode plate 71 by, for example, welding by resistance welding or the like. The second electrode terminal plate 74 functions as an external connection terminal for the negative electrode.

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

The second sealant film 76 is formed in an annular shape that surrounds the second electrode terminal plate 74 from the outside in the radial direction, and in a state of surrounding the second electrode terminal plate 74, the bottom wall of the second electrode terminal plate 74 and the second laminated member 60. It is arranged coaxially with the central axis O between the portion 66 and the central axis O.
The second sealant film 76 is heat-welded to the inner resin layer 62 of the bottom wall portion 66 of the second laminated member 60 and the lower surface of the second electrode plate 71, respectively. As a result, the second electrode plate 71 is heat-welded to the bottom wall portion 66 of the second laminated member 60 via the second sealant film 76.
Similar to the first sealant film 75, the second sealant film 76 is made of, for example, a thermoplastic resin such as polyethylene or polypropylene of poreolefin, or a non-woven fabric made of polypropylene or the like.

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. ..

(Action 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 becomes the second electrode plate 71. Since the fixed second electrode terminal plate 74 is exposed to the outside, the first electrode terminal plate 73 and the second electrode terminal plate 74 can each function as external connection terminals.
As a result, the secondary battery 1 can be used by using the first electrode terminal plate 73 and the second electrode terminal plate 74.

In particular, according to the secondary battery 1 of the present embodiment, since the positive electrode 10 and the negative electrode 20 are wound to form the electrode body 2, the electrode body 2 is wound in a flat shape without a protrusion. Therefore, it can be housed in the exterior body 3 at a high density. Therefore, the degree of freedom in shape can be improved, the volume ratio of the electrode body 2 to the total volume of the secondary battery 1 can be improved, and the volumetric efficiency of the laminated type secondary battery 1 can be improved. can do.

Further, as shown in FIGS. 7 and 8, the first insulating tape 40 and the second insulating tape 45 are attached to the eighth-stage positive electrode main body 12 and the eighth-stage negative electrode main body 22 arranged on the outermost peripheral side. Since the wound state can be maintained, it is possible to prevent the positive electrode 10 and the negative electrode 20 from being unwound. Therefore, the operation reliability of the secondary battery 1 can be ensured, and the work of incorporating the electrode body 2 into the exterior body 3 can be easily performed.

In particular, as shown in FIG. 7, the extension tape portion 41 can be used to further cover the side surface portion of the laminated electrode body 2. Specifically, the extension tape portion 41 is used to form the positive electrode body 12 on the outermost peripheral side (8th stage) on which the positive electrode terminal tab 14 is formed and the outermost peripheral side (8th stage) on which the negative electrode terminal tab 24 is formed. The positive electrode connection piece 13 connecting the seventh-stage positive electrode body 12 arranged one layer inside the negative electrode body 22 of the eye) can be covered with the separator 30.

As a result, even if the negative electrode terminal tab 24 is bent in a state where a part of the negative electrode terminal tab 24 is arranged outside the positive electrode connection piece 13 via the separator 30 when the electrode body 2 is accommodated, the extension tape The portion 41 can be used to prevent the negative electrode terminal tab 24 from coming into direct contact with the separator 30. Therefore, the region where the negative electrode terminal tab 24 may come into contact can be protected by using the extension tape portion 41.

Therefore, for example, even if the lithium metal is deposited in the shape of a needle on the negative electrode terminal tab 24 during charging, the inconvenience that the lithium metal penetrates the separator 30 can be prevented by using the extension tape portion 41. .. Therefore, the possibility of an internal short circuit can be reduced, and the secondary battery 1 with improved safety can be obtained.

As described above, according to the secondary battery 1 of the present embodiment, the possibility of an internal short circuit due to the negative electrode terminal tab 24 can be reduced, and a laminated type battery with improved safety can be obtained.

Further, since the electrode body 2 can be formed by repeatedly winding the positive electrode electrode 10 and the negative electrode electrode 20 in the same direction, the electrode body 2 can be efficiently formed, and the manufacturing efficiency of the secondary battery 1 itself is improved. Can be connected to. Further, since the positive electrode 10 and the negative electrode 20 are wound in the same direction, the first insulating tape 40 and the second insulating tape 45 including the extension tape portion 41 can be easily attached 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 embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. The embodiments and modifications thereof include, for example, those that can be easily assumed by those skilled in the art, those that are substantially the same, and those that have an equal range.

For example, in the above embodiment, the secondary battery 1 has been described as an example of the electrochemical cell, but the present invention is not limited to this case, and is, for example, a capacitor (for example, a lithium ion capacitor) or a primary battery. It doesn't matter.

Further, although the second electrode plate 71 is made of copper in the above embodiment, it may be made of nickel, for example. In this case, the second electrode terminal plate 74 can be omitted. That is, on the negative electrode side, the electrode terminal plate is not always indispensable and may not be provided. In this case, the second electrode plate 71 itself can function as an external connection terminal on the negative electrode side.
Further, it is not necessary that the entire exterior body 3 is formed of a laminated film, and at least a part of the exterior body 3 may be formed of a laminated film.

Further, in the above embodiment, the secondary battery 1 having a circular shape in a plan view has been described as an example, but the shape of the secondary battery 1 may be changed as appropriate. For example, as shown in FIG. 12, an oval-shaped secondary battery (electrochemical cell according to the present invention) 80 in which a straight portion and a semicircular portion are combined in a plan view may be used. In this case, as shown in FIG. 13, the shape of the electrode body 2 may be formed into an oval shape in a plan view corresponding to the outer shape of the secondary battery 80.

L1 ... 1st direction Z ... Lamination direction 1,80 ... Secondary battery (electrochemical cell)
2 ... Electrode body (laminated electrode body)
3 ... Exterior 4 ... Insulation 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 part 45 ... Second insulating tape

Claims (3)

A laminated electrode body having a positive electrode and a negative electrode superimposed on each other via a separator,
The insulating tape attached to the laminated electrode body and
An exterior body formed of a laminated film and accommodating the laminated electrode body inside is provided.
The positive electrode is integrally formed with a plurality of positive electrode bodies arranged along the stacking direction of the laminated electrode bodies, a positive electrode connecting piece for connecting the plurality of positive electrode bodies, and one of the plurality of positive electrode bodies. With a positive electrode terminal tab,
The negative electrode is integrally formed with a plurality of negative electrode bodies arranged along the stacking direction of the laminated electrode bodies, a negative electrode connection piece for connecting the plurality of negative electrode bodies, and one of the plurality of negative electrode bodies. With a negative electrode terminal tab,
In the laminated electrode body, the positive electrode body and the negative electrode body are alternately laminated in the stacking direction, and 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 formed. Formed to be placed on the outermost peripheral side,
The insulating tape is
A first insulating tape that is attached so as to cover the positive electrode body arranged on the outermost peripheral side with the separator interposed therebetween and maintains a laminated state of the positive electrode body.
A second insulating tape, which is attached so as to cover the negative electrode body arranged on the outermost peripheral side via the separator and maintains the laminated state of the negative electrode body, is provided.
The first insulating tape comprises a positive electrode connecting piece that connects the positive electrode body arranged on the outermost peripheral side and the positive electrode body arranged one layer inside the negative electrode body arranged on the outermost peripheral side. An electrochemical cell characterized by having an extension tape portion attached so as to cover the separator. In the electrochemical cell according to claim 1,
The extension tape portion is a separator that connects the positive electrode connecting piece that connects the positive electrode body arranged on the outermost peripheral side and the positive electrode body arranged one layer inside the negative electrode body arranged on the outermost peripheral side. An electrochemical cell that is attached so as to cover the entire surface through the electrode. In the electrochemical cell according to claim 1 or 2.
The plurality of positive electrode bodies are arranged along the first direction in the deployed state.
The positive electrode terminal tab is formed on the positive electrode body located at one end position in the first direction among the plurality of positive electrode bodies.
The plurality of the negative electrode bodies are arranged in the deployed state along the first direction.
The negative electrode terminal tab is formed on the negative electrode body located at one end position in the first direction among the plurality of negative electrode bodies.
The laminated electrode body is an electrochemical cell formed by repeatedly winding the positive electrode and the negative electrode, which are laminated along the first direction, in the same direction.

Images