JP7728087B2 - Film-encased battery - Google Patents

Description

The present invention relates to a film-cased battery.

Extremely thin electronic devices (hereafter referred to as "thin electronic devices") that have built-in power sources are now in practical use, such as IC cards with one-time password functions and displays, or tags and tokens (one-time password generators). To realize these thin electronic devices, it is essential to make the energy storage elements (primary batteries, secondary batteries, electric double-layer capacitors, etc.) that serve as their power sources smaller and thinner.

Film-cased batteries are an energy storage element suitable for miniaturization and thinning (see, for example, Non-Patent Document 1). Film-cased batteries have an electrode assembly housed within a film casing made of aluminum laminate film or the like. The electrode assembly has a positive electrode and a negative electrode arranged opposite each other with a separator interposed between them. Protruding from the film casing are a connection terminal electrically connected to the positive electrode and a connection terminal electrically connected to the negative electrode. These connection terminals are also called tab leads.

When a battery is incorporated into a device, the battery's connection terminals must be electrically connected to the device's circuitry. Connection methods include soldering, ultrasonic welding, and resistance welding, but these methods make it impossible to remove the battery. One method that makes it possible to remove the battery is to insert the battery's connection terminals into the device's connector socket.

In the past, there was a technique for forming a resin material or the like on the surface of a connection terminal to improve adhesion between the connection terminal of a secondary battery and the sealing material (sealant) provided between the connection terminal and the film exterior (see, for example, Patent Documents 1 and 2).

In addition, to prevent deformation of the connection terminal, there is a technology in which a film exterior is formed to cover one side of the connection terminal (see, for example, Patent Document 3). However, this technology is not designed to insert the connection terminal into a connector socket, so the film exterior gets in the way when connecting the battery to the connector.

In addition, to prevent the connection terminals protruding from the film exterior from bending, there is a technology in which a support sheet is provided by extending part of the film exterior outward, and the connection terminals are placed on top of this (see, for example, Patent Document 4).

In addition, in a structure in which multiple battery cells are stacked, there is a technology in which an insulating film is provided on both sides of the connection terminals between adjacent battery cells to prevent contact between the connection terminals protruding from each battery cell (see, for example, Patent Document 5).

JP 2011-159569 A Japanese Patent Application Laid-Open No. 2016-157516 Japanese Patent Application Laid-Open No. 2001-102014 Japanese Patent Application Laid-Open No. 2019-057521 Special table 2018-526802 publication

FDK Corporation, "Thin Manganese Dioxide Lithium Primary Battery," [online], [Retrieved December 10, 2020], Internet <URL: https://www.fdk.co.jp/battery/lithium/thin/>

When a battery is removable from a device's connector, there is a possibility of a reverse connection of the positive and negative terminals, where the battery's negative terminal comes into contact with the connector's positive terminal, and the battery's positive terminal comes into contact with the connector's negative terminal. When this reverse connection occurs, a reverse current flows within the device's circuitry, including the connector, potentially destroying the device.

One way to prevent reverse connection of positive and negative electrodes between the battery connection terminals and connector is to make the shape of the connection terminals and the connector socket asymmetrical, such as trapezoidal, so that they can only be inserted in the correct orientation. However, with film-cased batteries like the one described above, the connection terminals are thin, making it difficult to devise a unique shape.

In one aspect, the present invention aims to provide a film-cased battery that can protect equipment including a connector even if the positive and negative poles are reversed between the connection terminals of the film-cased battery and the connector.

In one embodiment, a film-sheathed battery is provided, comprising: an electrode assembly having a positive electrode and a negative electrode arranged opposite each other with a separator interposed therebetween; a film exterior housing that houses the electrode assembly; a first connection terminal that includes a flat-shaped first metal member electrically connected to the positive electrode and a portion thereof protruding from the film exterior housing, the first metal member being exposed over the entire surface of a first surface of the portion protruding from the film exterior housing, and a first insulator being formed on at least a portion of a second surface opposite the first surface; and a second connection terminal that includes a flat-shaped second metal member electrically connected to the negative electrode and a portion thereof protruding from the film exterior housing, the second metal member being exposed over the entire surface of a third surface of the portion protruding from the film exterior housing that faces the same direction as the first surface, and a second insulator being formed on at least a portion of a fourth surface opposite the third surface.

In one aspect, the present invention can protect equipment including a connector even if the positive and negative poles are reversed between the connection terminals of a film-covered battery and the connector.

1 is a perspective view showing an example of a film-covered battery according to the present embodiment. FIG. 2 is a side view of a portion of the film-covered battery of the present embodiment. FIG. 2 is a perspective view schematically showing layers included in the film-covered battery of the present embodiment. FIG. 1 is a diagram showing a first application example of a film-covered battery. 10 is a diagram showing an example in which the connection terminals of a film-covered battery are inserted into the connector socket with the positive and negative terminals facing inversely. FIG. FIG. 10 is a diagram showing a second application example of a film-covered battery.

Hereinafter, embodiments of the invention will be described with reference to the drawings.
Fig. 1 is a perspective view showing an example of a film-covered battery of the present embodiment, Fig. 2 is a side view of a portion of the film-covered battery of the present embodiment, and Fig. 3 is a perspective view schematically showing layers included in the film-covered battery of the present embodiment.

As shown in Figures 1 to 3, the film-covered battery 10 of this embodiment has an electrode assembly 12 having a positive electrode 12a and a negative electrode 12b arranged opposite each other with a separator 12c interposed therebetween, and a film covering 11 made of laminate films 11a and 11b that houses the electrode assembly 12. The film-covered battery 10 also has a connection terminal 13a that electrically connects to the positive electrode 12a and a connection terminal 13b that electrically connects to the negative electrode 12b.

Laminate films 11a and 11b are thermally laminated, for example, by extrusion lamination. Laminate films 11a and 11b are formed by sandwiching a metal layer, such as aluminum or stainless steel foil, between a resin layer and a heat-sealing layer.

As shown in FIG. 3, tab films 14a and 14b are attached to the sides of the laminate films 11a and 11b that contact the connection terminals 13a and 13b.
The film exterior body 11 made of such laminate films 11a and 11b has its heat-sealed layers heat-sealed to each other in the peripheral region, and is processed into a bag shape so as to enclose the electrode body 12 and the non-aqueous organic electrolyte solution.

The positive electrode 12a is formed by disposing a positive electrode material containing a positive electrode active material on one main surface of a current collector which is, for example, a metal plate or metal foil made of stainless steel or the like.
The separator 12c may be made of, for example, a cellulose product.

The negative electrode 12b is formed by disposing a negative electrode material containing a negative electrode active material on one main surface of a current collector which is, for example, a metal plate or metal foil made of stainless steel or the like.
When the film-covered battery 10 is a lithium primary battery, the positive electrode 12a is a current collector coated with a slurry-like positive electrode material containing a positive electrode active material such as _MnO2 (manganese dioxide), and the negative electrode 12b is a foil or flat plate of metallic lithium or a lithium alloy without a current collector.

The electrode body 12 may be heat-welded to the laminate films 11a and 11b to prevent misalignment.
Connection terminal 13a electrically connected to positive electrode 12a includes a flat metal member 13a1, a portion of which protrudes from film exterior body 11. Connection terminal 13b electrically connected to negative electrode 12b also includes a flat metal member 13b1, a portion of which protrudes from film exterior body 11.

The metal member 13a1 is, for example, a metal plate made of stainless steel, and the metal member 13b1 is, for example, a metal plate made of an alloy of Cu (copper) and Ni (nickel).
Furthermore, in the connection terminal 13a, a metal member 13a1 is exposed over the entire first surface of the portion protruding from the film exterior body 11, and an insulator 13a2 is formed on at least a portion of the second surface opposite the first surface.

Similarly, for the connection terminal 13b, a metal member 13b1 is exposed on the entire third surface of the portion protruding from the film exterior body 11, which faces the same direction as the first surface, and an insulator 13b2 is formed on at least a portion of the fourth surface opposite the third surface.

The first to fourth surfaces are surfaces whose normal vectors are in the thickness direction of the film-covered battery 10 (the z-axis direction in FIGS. 2 and 3).
1 to 3, the insulators 13a2 and 13b2 are formed on the tip sides of the second and fourth surfaces of the connection terminals 13a and 13b in the portions thereof that protrude from the film exterior body 11, but this is not limiting. The insulators 13a2 and 13b2 may be formed only in the intermediate portions between the base and the tip of the connection terminals 13a and 13b in the portions thereof that protrude from the film exterior body 11, or may be formed only on the base side.

Insulators 13a2 and 13b2 may be formed on the second and fourth surfaces, as well as on the surfaces of the tips of the connection terminals 13a and 13b that protrude from the film exterior body 11 (surfaces perpendicular to the first to fourth surfaces).

The insulators 13a2 and 13b2 are preferably formed by attaching a resin film or the like having an area equal to or smaller than the second and fourth surfaces to the metal members 13a1 and 13b1 after the film-covered battery 10 is assembled. This is because it is easy to form.

However, the method for forming the insulators 13a2 and 13b2 is not limited to the above example. For example, the insulators 13a2 and 13b2 may be applied to the second and fourth surfaces, or the insulators 13a2 and 13b2 may be formed by insulating processes such as anodizing.

Furthermore, the insulators 13a2 and 13b2 are not limited to resin. For example, the insulators 13a2 and 13b2 may be ceramic. Furthermore, the insulators 13a2 and 13b2 may each be made of a different material.

(Manufacturing example)
An example of manufacturing the film-covered battery 10 will be described below.
The positive electrode 12a is obtained by applying a water-based slurry of a positive electrode material to one main surface of a stainless steel current collector, except for the area where the metal member 13a1 of the connection terminal 13a is formed. The positive electrode material is, for example, adjusted to a composition of 90.2 parts by weight of _MnO2 , 5 parts by weight of acetylene black (AB), 3.7 parts by weight of styrene-butadiene rubber (SBR), and 0.8 parts by weight of hydroxyethyl cellulose (HEC).

_MnO2 is a positive electrode active material, AB is a conductive additive, SBR is a binder, and HEC is a thickener. The amount of the positive electrode material applied was 31 mg/ ^cm2 . After application, the substrate was dried and pressed, and then cut into a size of 20 × 13 mm (the size of the portion of the connection terminal 13a other than the area where the metal member 13a1 is formed), to obtain the positive electrode 12a.

In addition, during this cutting process, the metal member 13a1 of the stainless steel connection terminal 13a is also cut out at the same time. In other words, the metal member 13a1 is manufactured integrally with the stainless steel current collector of the positive electrode 12a.

The negative electrode 12b is obtained by cutting metallic lithium into a size of, for example, 19×12 mm.
The separator 12c is made of a cellulose product having a thickness of 20 μm.

The electrode assembly 12 is formed by laminating a positive electrode 12a, a separator 12c, and a negative electrode 12b in this order.
Such an electrode body 12 is obtained by bonding together a positive electrode 12a heat-sealed to the heat-sealing layer of a laminate film 11a and a negative electrode 12b heat-sealed to the heat-sealing layer of a laminate film 11b with a separator 12c sandwiched therebetween.

Tab films 14a and 14b are attached to the laminate films 11a and 11b in advance.
As described above, the metal member 13a1 of the connection terminal 13a, which is formed simultaneously with the positive electrode 12a, is connected to the positive electrode 12a. The metal member 13b1 of the connection terminal 13b is disposed between the thermal fusion layer of the laminate film 11b and the negative electrode 12b, and is thereby electrically connected to the negative electrode 12b.

With the electrode assembly 12 inserted, the laminate films 11a and 11b are bonded and sealed at three of their four sides to create a bag-shaped film exterior 11 with one side open. A non-aqueous organic electrolyte solution is then injected through the opening of the film exterior 11, impregnated under reduced pressure, and the film exterior 11 is then vacuum-sealed (the remaining side is sealed).

After sealing, a 180 μm thick PET (Polyethylene Terephthalate) film with adhesive is attached to the surfaces of the metal members 13a1 and 13b1 that face in the same direction (the second and fourth surfaces mentioned above) of the parts that protrude from the film exterior body 11. This completes the film-exterior battery 10.

The above manufacturing method is merely an example, and the manufacturing conditions can be changed as appropriate.
(Application examples and effects)
Hereinafter, application examples and effects of the film-covered battery of this embodiment will be described.

FIG. 4 is a diagram showing a first application example of a film-covered battery.
The connection terminals 13a and 13b of the film-covered battery 10 are inserted into the sockets 21a and 21b of the connector 20a.

Socket 21a is for the positive electrode (marked "+"), and socket 21b is for the negative electrode (marked "-"). Inside connector 20a, a positive terminal and a negative terminal are provided so that only the undersides of connection terminals 13a and 13b inserted into sockets 21a and 21b make contact.

For this reason, as shown in Figure 4, when the connection terminals 13a and 13b of the film-covered battery 10 are inserted into the sockets 21a and 21b with the positive and negative terminals facing the correct direction, power is normally supplied from the film-covered battery 10 to the connector 20a.

On the other hand, if the connection terminals 13a and 13b of the film-covered battery 10 are inserted into the sockets 21a and 21b in the opposite positive and negative directions, the insulators 13a2 and 13b2 of the connection terminals 13a and 13b will come into contact with the positive and negative terminals of the connector 20a.

FIG. 5 shows an example in which the connection terminals of a film-covered battery are inserted into the connector socket with the positive and negative terminals facing inversely.
5, the connection terminal 13b electrically connected to the negative electrode 12b is inserted into the positive electrode socket 21a. In this case, the insulator 13b2 of the connection terminal 13b contacts the positive electrode terminal 22a of the connector 20a, and the metal member 13b1 of the connection terminal 13b does not contact the positive electrode terminal 22a.

This prevents electrical conduction between the film-covered battery 10 and the connector 20a, suppressing the occurrence of reverse current and protecting the device including the connector 20a. In other words, the safety of the device is ensured.

One possible method is to make the connection terminals 13a, 13b and the sockets 21a, 21b asymmetrical, such as trapezoidal, so that they can only be inserted in the correct orientation. However, in the film-covered battery 10 described above, the connection terminals 13a, 13b are thin, making it difficult to devise a unique shape. According to the film-covered battery 10 of this embodiment, by providing the above-described insulators 13a2, 13b2 on the connection terminals 13a, 13b, even when thin connection terminals 13a, 13b are used, the device, including the connector 20a, can be protected in the event of reverse connection of the positive and negative poles, as described above. This is more effective when the thickness of the film-covered battery 10 is 1 mm or less, making it difficult to thicken the connection terminals 13a, 13b.

Furthermore, the film-cased battery 10 can be inserted and removed from the connector 20a. This allows the film-cased battery 10 to be replaced when it reaches the end of its battery life. In particular, for devices that use non-rechargeable primary batteries, making the battery removable allows for repeated use by simply replacing the battery even after the electronic capacity has run out, making the film-cased battery 10 particularly effective for primary batteries.

For example, if the film-covered battery 10 is a lithium primary battery, as described above, the positive electrode 12a may be formed by applying a slurry-like positive electrode material containing a positive electrode active material such as _MnO2 to one main surface of a current collector, and the negative electrode 12b may be formed by using, for example, foil-shaped or flat-plate-shaped metallic lithium or a lithium alloy.

FIG. 6 is a diagram showing a second application example of a film-covered battery.
6, connector 20b is an open/close type, and has a plurality of positive terminals (e.g., positive terminal 23a) and a plurality of negative terminals (e.g., negative terminal 23b) formed on the base portion. In such connector 20b, when closed, the lower surfaces of connection terminals 13a and 13b come into contact with one of the plurality of positive terminals and one of the plurality of negative terminals.

As shown in Figure 6, when the connection terminal 13a of the film-covered battery 10 contacts one of the multiple positive terminals of the connector 20b, and the connection terminal 13b contacts one of the multiple negative terminals of the connector 20b, power is normally supplied to the connector 20b from the film-covered battery 10.

On the other hand, when connection terminal 13a of film-covered battery 10 contacts one of the multiple negative terminals of connector 20b and connection terminal 13b contacts one of the multiple negative terminals of connector 20b, insulators 13a2 and 13b2 of connection terminals 13a and 13b will come into contact with one of the multiple positive terminals and one of the multiple negative terminals of connector 20b.

Therefore, even when such a connector 20b is used, if the positive and negative electrodes are connected in reverse, electrical conduction does not occur between the film-covered battery 10 and the connector 20b, suppressing the occurrence of reverse current and protecting the equipment including the connector 20a. In other words, the safety of the equipment is ensured.

The above describes one aspect of the film-covered battery of the present invention based on an embodiment, but these are merely examples and are not limited to the above description.

REFERENCE SIGNS LIST 10 Film-cased battery 11 Film casing 11a, 11b Laminate film 12 Electrode body 12a Positive electrode 12b Negative electrode 12c Separator 13a, 13b Connection terminals 13a1, 13b1 Metal member 13a2, 13b2 Insulator 14a, 14b Tab film

Claims (5)

an electrode assembly having a positive electrode and a negative electrode arranged opposite each other with a separator interposed therebetween;
a film exterior body that houses the electrode body;
a first connection terminal including a flat-shaped first metal member electrically connected to the positive electrode and a portion of which protrudes from the film exterior housing, the first metal member being exposed over the entire first surface of the portion protruding from the film exterior housing, and a first insulator separated from the film exterior housing being formed on a second surface opposite the first surface and on a portion of the portion protruding from the film exterior housing ;
a second connection terminal including a flat second metal member electrically connected to the negative electrode and having a portion protruding from the film exterior housing, the second metal member being exposed over the entire surface of a third surface of the portion protruding from the film exterior housing, the third surface facing the first surface, and a second insulator separated from the film exterior housing and the first insulator being formed on a portion of the portion protruding from the film exterior housing on a fourth surface opposite the third surface;
A film-covered battery comprising: The film-cased battery described in claim 1, characterized in that the first insulator and the second insulator are resin. The film-cased battery described in claim 1 or 2, characterized in that it has a thickness of 1 mm or less. The film-covered battery described in any one of claims 1 to 3 is a primary battery. A film-cased battery as described in any one of claims 1 to 4, characterized in that the positive electrode contains manganese dioxide as a positive electrode active material, and the negative electrode is metallic lithium or a lithium alloy.