JPH10112322A - Battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light battery by constituting layers of thin films containing specific resin and electronic conductive thin films in the inner electrode. SOLUTION: Thin films P consist of thermoplastic resin such as polyethylene, polyethylene terephthalate, or polypropylene, and layered current collectors are bound with their thin films P surface. Thin films E used in the current collector of a positive electrode 3 is preferably made of aluminum Al, and thin films E for a positive electrode 4, which are preferably made of copper Cu or nickel Ni, are piled up on thin films P to make two or three layers structure of them. Using the positive electrode 3 and the positive electrode 4 having layer structure of thin films P and thin films E provides a lighter battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-aqueous electrolyte battery.

[0002]

2. Description of the Related Art In recent years, electronic devices such as a portable radio telephone, a portable personal computer, and a portable video camera have been developed, and various electronic devices have been reduced in size to be portable. Along with this, a battery having a high energy density and a light weight is also adopted as a built-in battery. A typical battery that satisfies such a requirement is an active material such as lithium metal or lithium alloy, or a host material containing lithium ions (here, a host material refers to a material that can occlude and release lithium ions). Lithium intercalation compound occluded in a certain carbon is used as a negative electrode material, and LiC
This is a lithium secondary battery using an aprotic organic solvent in which a lithium salt such as IO ₄ and LiPF ₆ is dissolved as an electrolyte.

A lithium secondary battery has a negative electrode plate in which the above-mentioned negative electrode material is held by a negative electrode current collector as a support, and reversibly electrochemically reacts with lithium ions like a lithium cobalt composite oxide. It consists of a positive electrode plate holding the positive electrode active material on a positive electrode current collector as its support, and a separator that holds an electrolytic solution and intervenes between the negative electrode plate and the positive electrode plate to prevent a short circuit between both electrodes. .

In the case of a rectangular or cylindrical battery, the positive electrode plate, the separator and the negative electrode plate are each formed by laminating thin sheets or foils in order, and spirally wound into a battery container. Is stored. Therefore, the plates are
Generally, an active material or a host material is mixed with an organic binder, a conductive agent and a solvent to form a paste, which is applied to the surface of the support, dried, and then pressure-formed together with the support in the thickness direction. You. Conventionally, as the current collector of the electrode plate,
Since it is necessary to have its own conductivity, a metal foil such as copper or aluminum has been used. In the conventional nonaqueous electrolyte battery, the weight of the metal current collector occupies 5 to 10% of the total weight.

[0005]

In the case of equipment using a battery as a power source, not limited to a lithium battery, there is no end to the demand for reducing the weight of the entire equipment. Therefore, the lighter the battery performance, the more favorable the user. However, there are limitations in production and handling in reducing the thickness of the metal foil of the current collector. Therefore, an object of the present invention is to provide a light battery by deviating from the concept of the conventional current collector and making the structure of the current collector completely different from the conventional one.

[0006]

In order to achieve the object, a battery of the present invention comprises an internal electrode comprising a mixture containing an active material or a host material and a film-like current collector holding the mixture. In the battery, first, the electrode is characterized in that the current collector is a layered body of a thin film P containing a resin and an electron conductive thin film E. The thin film P may be a composition of a resin and another material in addition to the one composed of only the resin.

The battery of the present invention is lighter than a battery having a current collector made of a metal foil of the same thickness, since the current collector has a thin film P containing a resin as a core. Thus, the battery of the present invention
Because the current collector is light, it is light overall. Of course, it is not limited to an organic electrolyte battery, and there is no distinction between a primary battery and a secondary battery, and an alkaline battery, a Ni-Cd battery, a Ni-HM
It goes without saying that weight reduction can be expected for all batteries such as batteries and lead batteries.

[0008] In the battery of the present invention, in addition to the above-mentioned first feature, secondly, the electrode has a laminated structure of a mixture layer, a current collector, a current collector, and a mixture layer in order in a cross section in a thickness direction. It is characterized by having. This is for the following reasons. Generally, an internal electrode of a small battery such as an organic electrolyte battery is prepared by applying a mixture obtained by adjusting an active material or a host material together with a binder or a conductive agent into a paste, and applying the mixture to a current collector. The mixture is applied to both sides of the current collector to increase the energy density of the battery. In this case, there is a problem that the accuracy of the thickness of the mixture applied to the second surface is inferior to the thickness of the mixture applied to the first surface of the current collector. This is because the variation in the thickness of the first surface is superimposed on the application accuracy of the second surface because the second surface is behind the first surface. When the thickness of the mixture varies as described above, current concentrates on a thick portion. For example, in a lithium battery, Li is deposited to cause a reduction in capacity and a deterioration in life. Moreover, it becomes thermally unstable due to Li electrodeposition.

Therefore, in the present invention, after the mixture is applied only to the first surface of the current collector having a length twice as long as the designed dimension of the electrode, the current collector is folded in the middle so that the mixture layer is on the outside. . Alternatively, two current collectors having the mixture applied only to the first surface are overlapped so that the mixture layer is on the outside. Although the thickness of the current collector is doubled when viewed as a whole electrode, the thickness of the current collector is smaller than the thickness of the mixture layer, and the current collector applied to the present invention contains a resin. Since it is composed of the thin film P and the thin film E, the thickness per sheet can be made smaller than that of a conventional current collector. Therefore, in the electrode of the present invention, the thickness of the mixture layer becomes more uniform than before without increasing the overall thickness. As a result, the battery of the present invention can be designed with high accuracy in terms of safety, capacity, and life.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the resin contained in the thin film P include thermoplastic resins such as polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). It is preferable that the current collectors in the laminated structure are stacked and bonded so that the thin films P face each other. Adhesives include polyimide, polyamideimide, polyetheramide, polyetheramideimide, polyester, nylon, acrylic, urethane, phenol, epoxy, silicone, ABS, NBR, etc. There is.

The thin film E to be superimposed on the surface of the thin film P includes electroless plated Ni, Cu, evaporated Cu,
Al or foils of these metals are preferred. In particular, aluminum Al is preferable for the thin film E of the current collector of the positive electrode. This is because aluminum has excellent corrosion resistance and does not dissolve into the electrolyte even during charging when the positive electrode has a high potential. On the other hand, particularly preferred as the thin film E of the current collector of the negative electrode is copper Cu or nickel Ni. Copper can be made extremely thin by vapor deposition to reduce the weight of the current collector. Also, copper is
It is experimentally known that it melts around 3.9 V vs. Li / Li ⁺ . Therefore, the proper working voltage range is 0
It is up to Ｖ3V, and if it is higher, it will be dissolved. On the other hand, Ni is 4.0 to 4.2 V vs. Li / Li ⁺
Since it does not melt to a maximum, a wide potential region can be used.

The layer structure of the layered body is composed of a thin film P and a thin film E.
It may be a layer or three layers of thin film E, thin film P and thin film E in this order. As a means for forming a layer, various known means including vapor deposition and plating can be applied. The thin film P and the thin film E may be in close contact with each other, or may be in close contact with each other. The shape of the entire electrode is not limited to a spiral shape.

[0013]

【Example】

-Example-An example of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of the organic electrolyte battery of the embodiment. The organic electrolyte battery 1 is a prismatic lithium secondary battery in which an electrode group 2 including a positive electrode plate 3, a negative electrode plate 4, and a separator 5 is housed in a battery case 6 together with a non-aqueous electrolyte (not shown).

The positive electrode plate 3 is a current collector in which a lithium-cobalt composite oxide is held as an active material. The current collector was obtained by laminating a 4 μm-thick aluminum foil on one side of a 4.6 μm-thick PET film and bonding it with an adhesive. The positive electrode plate 3 was prepared by mixing 8 parts of polyvinylidene fluoride as a binder and 5 parts of acetylene black as a conductive agent together with 87 parts of an active material, adding an NMP solvent to prepare a paste, and then mixing the mixture. The collector is coated on the aluminum foil side, dried and pressurized, and then folded at the center in the longitudinal direction so that the mixture layer is on the outside, and the facing PET films are bonded to each other with a dry laminating adhesive. (Takeda A-515, Takeda Pharmaceutical Co., Ltd.). As shown in FIG. 2, the obtained positive electrode plate 3 includes a current collector including a mixture layer 31, an aluminum foil 32 and a PET film 33, a current collector including a PET film 33 and an aluminum foil 32 in a thickness direction, In addition, the mixture layer 31 has a laminated structure.

The current collector of the negative electrode plate 4 is a 4.6 μm thick P
It was obtained by bonding a copper foil having a thickness of 1 μm to one side of the ET film with an adhesive. The negative electrode plate 4 is provided with a graphite (graphite) 86 as a host material on the surface of the current collector on the copper foil side.
And 14 parts of polyvinylidene fluoride as a binder were mixed to prepare a paste, and then the mixture was applied to the surface of the current collector on the side of the copper foil, dried, and pressed to form a positive electrode plate 3. It was manufactured by bending and bonding resin films to each other in the same manner as above.

The separator 5 is a polyethylene microporous membrane. The electrolyte was ethylene carbonate: diethyl carbonate = 1: 1 containing LiPF6 at 1 mol / l.
(Volume ratio).

Each dimension is such that the positive electrode plate 3 has a thickness of 180 μm.
m, width 29 mm, separator 5 thickness 25 μm, width 3
3 mm, the negative electrode plate 4 has a thickness of 180 μm and a width of 31 mm. The negative electrode plate 4 is superposed in order and wound around the polyethylene core in the shape of an ellipse.
It is stored in. The battery case 6 has a thickness of 0.3 mm,
The surface of an iron main body having an inner size of 33.1 × 46.5 × 7.5 mm is nickel-plated with a thickness of 5 μm, and a hole 12 for injecting an electrolyte is provided at an upper side portion.

The positive electrode plate 3 includes a safety valve 8 and a positive electrode terminal 1.
0 is connected via a positive electrode lead 11 to a terminal 10 of a case lid 7 provided with a zero. The negative electrode plate 4 is connected to a negative electrode lead (not shown) welded to the lower surface of the lid 7. Then, the battery is sealed by laser welding the lid 7 to the case 6.

The weight of the completed battery was 16 g.
This battery was charged at a constant current of 1 CmA to a final charge voltage of 4.1 V, and then 2.5 m in diameter from the side of the case 6 of the battery 1.
m was passed through an iron nail and observed for a while, but the electrolyte did not ignite.

Comparative Example A comparison was made under the same conditions as in Example 1 except that a 20 μm thick aluminum foil was used as the current collector of the positive electrode plate 3 and a 20 μm thick copper foil was used as the current collector of the negative electrode plate 4. Batteries were manufactured. The weight of this battery was 20 g. When an iron nail having a diameter of 2.5 mm was passed through the side of the case 6 of the battery 1, smoke was emitted 30 seconds later.

[0021]

As described above, according to the present invention, the battery can be reduced in weight, which is useful as a component of a portable electronic device.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an organic electrolyte battery of an example.

FIG. 2 is a cross-sectional view showing an electrode of an organic electrolyte battery of an example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Organic electrolyte battery 2 Electrode group 3 Positive electrode plate 4 Negative electrode plate 5 Separator 6 Battery case 7 Case cover 31 Mixture layer 32 Foil (Electron conductive thin film E) 33 PET film (Thin film P)

Claims (4)

[Claims] 1. A battery in which an internal electrode comprises a mixture containing an active material or a host material and a film-like current collector holding the same, wherein the electrode comprises a thin film P containing a resin containing a resin. And a layered body of an electron-conductive thin film E and a laminated structure of a mixture layer, a current collector, a current collector, and a mixture layer in order in a cross section in a thickness direction. 2. The battery according to claim 1, wherein the battery is an organic electrolyte battery such as an organic electrolyte battery or a polymer electrolyte battery. 3. The battery according to claim 1, wherein the resin of the thin film P has a heat distortion temperature lower than the ignition point of the organic electrolyte. 4. The resin of the thin film P is made of polyethylene (P
E), a thermoplastic resin such as polyethylene terephthalate (PET) or polypropylene (PP).
4. The battery according to any one of 3.