JP7224770B2 - Storage element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a laminate type electric storage device.

In recent years, extremely thin electronic devices (hereinafter also referred to as devices) with a built-in power supply, such as IC cards equipped with a one-time password function and a display, or tags and tokens (one-time password generators), are becoming widespread. In order to realize these devices, it is essential to reduce the size and thickness of the power storage elements (primary batteries, secondary batteries, electric double layer capacitors, etc.) that serve as power sources. As a typical energy storage element suitable for miniaturization and thinning, there is a laminate type energy storage element described in Patent Document 1 below.

FIG. 1A shows the appearance of a general laminate-type energy storage device (hereinafter also referred to as an energy storage device). Further, FIG. 1B shows an exploded perspective view of the electric storage element shown in FIG. 1A. As shown in FIG. 1A, the power storage element 101 has a flat plate-like appearance, and the power generation element is sealed in a flat rectangular bag-like exterior body 112 made of a laminate film. A positive electrode terminal plate 104 and a negative electrode terminal plate 108 (hereinafter also collectively referred to as electrode terminal plates) are led out from one side of the rectangular exterior body 112 .

Next, the structure of the storage element 101 will be described with reference to FIG. 1B. In FIG. 1B, some members and parts are hatched so that they can be easily distinguished from other members and parts. As shown in FIG. 1B, the exterior body 112 is formed by welding the outer edge regions 14 of two sheets of laminate films (113a, 113b) facing each other, and the electrode body 2 is shown inside the exterior body 112. It is sealed with an electrolyte that does not The laminate films (113a, 113b) have a metal foil such as an aluminum foil or a stainless steel foil as a base material, and an adhesive layer made of a heat-meltable resin such as polypropylene is laminated on one main surface of the base material. It is. The exterior body 112 is processed into a bag shape by stacking two laminate films (113a, 113b) so that their adhesive layers face each other, and then welding the outer edge regions 14 together. is.

Assuming that the direction in which the two laminate films (113a, 113b) face each other is the vertical direction, the electrode assembly 2 consists of a sheet-like positive electrode 4 and a sheet-like negative electrode 8, which are arranged in the vertical direction with a separator 6 interposed therebetween. It is crimped in a laminated state. The positive electrode 4 is formed by disposing a positive electrode material 5 containing a positive electrode active material on one main surface of a positive electrode current collector 103 made of a metal plate or metal foil. The negative electrode 8 is formed by disposing a negative electrode material 9 containing a negative electrode active material on one main surface of a negative electrode current collector 7 made of a metal plate, metal foil, or the like. The positive electrode 4 and the negative electrode 8 are laminated such that the positive electrode material 5 and the negative electrode material 9 face each other with the separator 6 interposed therebetween. One ends of a strip-shaped positive electrode terminal plate 104 and a strip-shaped negative electrode terminal plate 108 are attached to the positive electrode current collector 3 and the negative electrode current collector 7, respectively. The other end sides of the positive electrode terminal plate 104 and the negative electrode terminal plate 108 are led out from one side of the exterior body 112 .

If the power storage element 101 is a lithium primary battery, the positive electrode 4 is obtained by coating the surface of the positive electrode current collector 103 with a slurry-like positive electrode material 5 containing a positive electrode active material such as manganese dioxide. The negative electrode 8 is obtained by press-bonding a foil-shaped or flat plate-shaped lithium metal or lithium alloy to the negative electrode current collector 7 . Patent Document 1 describes characteristics, discharge performance, and the like of a thin manganese dioxide lithium primary battery, which is a laminate-type storage element that is actually on the market.

JP 2018-010751 A

FDK Corporation, “Thin Manganese Dioxide Lithium Primary Battery”, [online], [searched on March 14, 2018], Internet <URL: http://www.fdk.co.jp/battery/lithium/lithium_thin. html>

In the general laminate-type energy storage device described above, since the electrode terminal plates protrude outside of the exterior body, a space is required to accommodate the electrode terminal plates in addition to the exterior body when incorporated into a device. Become.

In addition, when it is necessary to increase the voltage by connecting a plurality of storage elements in series according to the operating voltage of the device, the electrode terminal plates of the plurality of storage elements are connected using wiring members. Therefore, the device requires more space for housing the wiring member. A troublesome work of connecting the electrode terminal plates with wiring members is also required.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a laminate-type electric storage device that can be miniaturized and that can be easily connected to each other.

One aspect of the present invention for achieving the above object is a power storage element in which an electrode body is housed in an exterior body together with an irregular-shaped electrolyte,
By stacking in the vertical direction, the current collectors of the positive electrode and the negative electrode can be in direct surface contact and connected in series.
The electrode body is formed by stacking a sheet-like positive electrode and a negative electrode in the vertical direction with a separator interposed therebetween,
The exterior body is formed by welding the outer edges of two laminate films stacked in the vertical direction, and has an opening in the center of the upper surface and the lower surface,
The positive electrode is formed by disposing a positive electrode material containing a positive electrode active material on one main surface of the current collector of the flat positive electrode,
The negative electrode is formed by disposing a negative electrode material containing a negative electrode active material on one main surface of the current collector of the flat negative electrode,
The positive electrode and the negative electrode face each other with the separator interposed therebetween,
In the electrode assembly, one of the positive and negative collectors is arranged on the uppermost layer, and the other of the positive and negative collectors is arranged on the lowermost layer,
The current collectors of the uppermost layer and the lowermost layer have peripheral edges welded to the laminate film and are exposed to the outside from the opening of the outer package,
One of the current collectors of the uppermost layer and the lowermost layer protrudes outward from the surface of the outer package, and the other is exposed to the outside from the opening in a recessed state from the surface of the outer package,
In the exterior body, the opening on the side where the current collector is exposed in a recessed state is formed in a shape that includes the planar shape of the upper end surface of the current collector on the projecting side .
The storage device is characterized by:

One of the positive electrode current collector and the negative electrode current collector may be a power storage element that protrudes outward from the surface of the exterior body. The electrode body can also be a storage element in which one positive electrode and one negative electrode are laminated with a separator interposed therebetween.

ADVANTAGE OF THE INVENTION According to this invention, the laminated-type electrical storage element which can be reduced in size and can be easily connected to each other is provided.

It is a figure which shows the external appearance of a general lamination-type electrical storage element. FIG. 2 is an exploded perspective view of a general laminate-type energy storage device; 1 is an external view of an electric storage device according to an example of the present invention when viewed from above; FIG. FIG. 3 is an external view of the electric storage element according to the above example as viewed from below; It is a figure which shows the structure of the electrical storage element which concerns on the said Example. FIG. 4 is a diagram showing a state in which the two storage devices according to the above embodiments are connected in series;

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in the drawings used for the following description, the same or similar parts may be denoted by the same reference numerals, and redundant description may be omitted. Parts marked with reference numerals in one drawing may not be marked with reference numerals in other drawings if unnecessary.

=== Example ===
<Structure of power storage element>
2A and 2B show the appearance of the storage device 1 according to the example of the present invention. Further, FIG. 3 shows the structure of the storage device 1 according to this example. 1A and 1B, FIG. 2A is a perspective view of the storage element 1 viewed from above, and FIG. 2B is a perspective view of the storage element 1 viewed from below. Fig. 3 is a perspective view when viewed; FIG. 3 is a vertical cross-sectional view of the electric storage device 1 cut along a plane including the vertical direction.

As shown in FIGS. 2A and 2B, the electric storage element 1 has a rectangular flat plate shape, and rectangular openings (15a, 15b) are provided in the centers of the upper surface and the lower surface of the exterior body 12, respectively. is formed. In this embodiment, the planar shape of the exterior body 12 and the openings (15a, 15b) is square. A portion of the positive electrode current collector 3 is exposed through an opening 15 a on the upper surface of the outer package 12 , and a portion of the negative electrode current collector 7 is exposed through an opening 15 b on the lower surface of the outer package 12 . As a result, the regions exposed from the openings (15a, 15b) of the upper surface of the positive electrode current collector 3 and the lower surface of the negative electrode current collector 7 become the positive electrode terminal 24 and the negative electrode terminal 28, respectively. Note that, in this embodiment, the positive electrode terminal 24 is exposed from the opening 15 a so as to protrude above the surface of the exterior body 12 . In the general energy storage element 101 shown in FIGS. 1A and 1B, the electrode terminal plates (104, 108) protrude from one side of the exterior body 112 having a rectangular planar shape. , the electrode terminal plate does not protrude from one side of the exterior body 12 having a rectangular planar shape.

As shown in FIG. 3 , an electrode assembly 2 in which a positive electrode 4 and a negative electrode 8 are stacked and crimped with a separator 6 interposed in between a positive electrode 4 and a negative electrode 8 in an exterior body 12 of the storage device 1 , similar to a general storage device 101 . is stored. In this embodiment, in the electrode body 2 , the positive electrode current collector 3 is arranged in the uppermost layer of the electrode body 2 and the negative electrode current collector 7 is arranged in the lowermost layer of the electrode body 2 . The exterior body 12 is formed by welding the outer edge regions 14 of two laminate films (13a, 13b) facing each other. In addition, on each of the upper surface of the positive electrode current collector 3 and the lower surface of the negative electrode current collector 7, the peripheral edge portions 16 not exposed from the openings (15a, 15b) are welded to the laminate films (13a, 13b). . As a result, the exterior body 12 is sealed so that the electrolytic solution does not leak to the outside.

As described above, in the electric storage device 1 according to the present embodiment, the flat electrode terminals (24, 28) are arranged on the upper surface and the lower surface of the outer package 12. As shown in FIG. 1A and 1B, the area of the electrode terminal plates (104, 108) of the laminate-type energy storage element 101 when viewed from above is can be reduced by Therefore, the power storage device 1 can make a device using itself as a power source smaller. Alternatively, the device can incorporate an energy storage element 1 that is larger in size and has a larger capacity than the conventional energy storage element 101, extending the operating time. A device using the storage element 1 as a power source is provided with terminals that contact the positive electrode terminal 24 arranged on the upper end surface of the storage element 1 and the negative electrode terminal 28 arranged on the lower end surface of the storage element 1 respectively. All you have to do is leave it. In addition, in the storage element 1, the surface area of the electrode terminals (24, 28) can be increased compared to the electrode terminal plates (104, 108) of the conventional storage element 101. FIG. Therefore, the contact resistance between the electrode terminals (24, 28) of the storage element 1 and the terminals of the device is reduced, and the storage device 1 can further extend the operating time of the device.

Further, the positive electrode terminal 24 of the electric storage device 1 according to the present embodiment protrudes outward from the surface of the exterior body 12, and the negative electrode terminal 28 is recessed from the surface of the exterior body 12 by the thickness of the laminate film 13b. I'm in. Therefore, the user of the device and the storage element 1 can easily distinguish between the positive terminal 24 and the negative terminal 28 of the storage element 1, and the possibility of connecting to the device with the wrong polarity is reduced.

<Procedure for sealing the outer package>
Next, an example of the procedure for sealing the exterior body 12 will be given with reference to FIGS. 2A, 2B, and 3A. First, two rectangular laminate films (13a, 13b) having rectangular openings (15a, 15b) in the center are prepared. Then, the two laminate films (13a, 13b) are laminated so that their adhesive layers face each other. Next, the two laminate films (13a, 13b) are welded along three sides to make the laminate films (13a, 13b) into a bag shape. The electrode body 2 is housed in the bag-shaped laminated films (13a, 13b), and the central portions of the positive electrode current collector 3 and the negative electrode current collector 7 are exposed from the openings (15a, 15b). Further, the peripheral edge portions 16 of the positive electrode current collector 3 and the negative electrode current collector 7 are thermally welded to the regions facing the peripheral edge portions 16 in the laminate films (13a, 13b).

Then, the electrolytic solution is injected into the exterior body 12 from one side of the outer edge region 14 of the laminate films (13a, 13b) that is not welded. Finally, the outer edge region 14 of the laminate films (13a, 13b) is heat-sealed to seal the exterior body 12. As shown in FIG. As a result, while the electrode body 2 and the electrolytic solution are sealed in the exterior body 12, the positive electrode current collector 3 and the negative electrode current collector 7 are connected to the positive terminal 24 and the negative electrode respectively from the openings (15a, 15b). It is exposed as terminal 28 .

<Series connection of storage elements>
Next, a method for connecting a plurality of storage elements 1 in series will be described. FIG. 4 shows a longitudinal sectional view of two storage elements (1a, 1b) connected in series. As shown in FIG. 4, in order to connect two storage elements (1a, 1b) in series, the two storage elements (1a, 1b) should be connected so that the terminals (24, 28) of the same polarity face in the same vertical direction. ) can be stacked on top of each other. In the example shown in FIG. 4, the upper end surface of the positive electrode terminal 24 of the lower storage element 1b is in contact with the lower end surface of the negative electrode terminal 28 of the upper storage element 1a. If the opening 15b on the side of the negative electrode terminal 28 formed in the exterior body 12 is formed in a shape that includes the planar shape of the upper end surface of the positive electrode terminal 24, the positive electrode terminal 24 of the lower storage element 1b can be opened. Surface contact is ensured with the negative terminal 28 of the upper storage element 1 .

In this way, the electrode bodies 2 of the storage device 1 according to the embodiment can flexibly cope with various voltages by connecting an arbitrary number of them in series. Further, in the electric storage device 1 according to the example, wiring members are not required when connecting a plurality of devices in series. Therefore, it is not necessary to provide a space for housing the wiring member inside the device using a plurality of power storage elements 1 connected in series. In addition, complicated work for connecting wiring members becomes unnecessary. Therefore, the storage device 1 can also reduce the manufacturing cost of the device.

===Other embodiments===
The electrode body 2 provided in the storage device 1 according to the above example was a "single-layer type" having only one configuration in which one positive electrode 4 and one negative electrode 8 were laminated with a separator 6 interposed therebetween. The storage element 1 having the single-layer electrode body 2 is extremely thin with a thickness of about 0.5 mm, and is sufficiently thin even when a plurality of electrodes are stacked. In addition, when a plurality of storage elements 1 are stacked and connected in series, the output voltage of one storage element 1 is the minimum unit, so that a wider variety of voltages can be handled.

Of course, the electrode body 2 is configured such that one positive electrode 4 and one negative electrode 8 face each other via a separator 6 as one unit cell, and a plurality of unit cells are connected in series. The unit cells may be stacked vertically. The electrode body composed of a plurality of sets of unit cells connected in series is housed in one exterior body, and the upper current collector in the uppermost unit cell and the lower current collector in the lowermost unit cell are exposed from the openings of the exterior body 12 as electrode terminals of different polarities.

In the storage element 1 according to the above-described example, the positive electrode terminal 24 protrudes outward from the surface of the exterior body 12, but a part of the negative electrode current collector 7 may protrude from the opening 15b. Moreover, both the positive electrode current collector 3 and the negative electrode current collector 7 may protrude from the openings (15a, 15b). Alternatively, the positive and negative current collectors ( 3 , 7 ) may be recessed with respect to the surface of the exterior body 12 . When connecting in series storage elements having both current collectors (3, 7) recessed with respect to the surface of the exterior body 12, the positive terminal of one storage element and the negative terminal of the other storage element are connected in series. A plate-like conductor is interposed between them, and the thickness of the conductor may be made larger than the thickness of the two laminate films.

The shape of the openings (15a, 15b) of the exterior body 12 is not limited to rectangular, and may be any shape such as circular or triangular.

In the electric storage device 1 according to the above-described embodiment, the liquid electrolytic solution is enclosed as the electrolyte in the exterior body 12. However, for example, a polymer electrolyte obtained by impregnating a polymer with the electrolytic solution, a gel electrolyte, or the like is indefinite. It suffices that the shape of the electrolyte is enclosed in the package 12 .

1,101 power storage element 2 electrode body 3,103 positive electrode current collector 4 positive electrode 5 positive electrode material 6 separator 7 negative electrode current collector 8 negative electrode 9 negative electrode material 11 exposed portion 12,112 exterior body , 13a, 13b, 113a, 113b laminate film 14 outer edge region 15a, 15b opening 24 positive terminal 28 negative terminal 104 positive terminal plate 108 negative terminal plate

Claims (2)

A power storage element in which an electrode body is housed in an exterior body together with an irregular-shaped electrolyte,
By stacking in the vertical direction, the current collectors of the positive electrode and the negative electrode can be in direct surface contact and connected in series.
The electrode body is formed by stacking a sheet-like positive electrode and a negative electrode in the vertical direction with a separator interposed therebetween,
The exterior body is formed by welding the outer edges of two laminate films stacked in the vertical direction, and has an opening in the center of the upper surface and the lower surface,
The positive electrode is formed by disposing a positive electrode material containing a positive electrode active material on one main surface of the current collector of the flat positive electrode,
The negative electrode is formed by disposing a negative electrode material containing a negative electrode active material on one main surface of the current collector of the flat negative electrode,
The positive electrode and the negative electrode face each other with the separator interposed therebetween,
In the electrode assembly, one of the positive and negative collectors is arranged on the uppermost layer, and the other of the positive and negative collectors is arranged on the lowermost layer,
The current collectors of the uppermost layer and the lowermost layer have peripheral edges welded to the laminate film and are exposed to the outside from the opening of the outer package,
One of the current collectors of the uppermost layer and the lowermost layer protrudes outward from the surface of the outer package, and the other is exposed to the outside from the opening in a recessed state from the surface of the outer package,
In the exterior body, the opening on the side where the current collector is exposed in a recessed state is formed in a shape that includes the planar shape of the upper end surface of the current collector on the projecting side .
A power storage device characterized by: 2. The storage element according to claim 1, wherein said electrode assembly is formed by laminating one positive electrode and one negative electrode with said separator interposed therebetween.

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