JPH09283149A - Collector for battery plate and battery using this collector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a collector, which is effective for the weight reduction and non-combustible characteristic of a battery, by forming a collector for holding the active material or the host material in a battery of a specified layered body. SOLUTION: An organic electrolyte battery such as an organic liquid- electrolyte battery and a high molecular electrolyte battery is desirable. In this battery 1, a collector for holding the active material or the host material of electrodes 3, 4 is formed of a layered body of a resin film made of the thermoplastic resin such as polyethylene terephthalate and PP, of which thermal deforming temperature is lower than the igniting point of the organic electrolyte, and an electron conductive thin film made of the metal, to which non-electrolyte plating or deposition, is performed. A thin film of the collector of the positive electrode is desirably made of Al, and a thin film of the collector of the negative electrode is desirably made of Cu or Ni.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current collector of a battery electrode plate such as a lithium secondary battery electrode plate and a battery using the current collector.

[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, as a built-in battery, a battery having a high energy density and being lightweight is adopted. A typical battery satisfying such requirements is an active material such as lithium metal or a lithium alloy, and a lithium ion host material (here, the host material means a material capable of inserting and extracting lithium ion). LiCI such as intercalation occluded in carbon is used as a negative electrode material, and LiCI
The lithium secondary battery uses an aprotic organic solvent in which a lithium salt such as O ₄ or LiPF ₆ is dissolved as an electrolytic solution.

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 collector of the electrode plate,
Metallic foils such as copper and aluminum have been used because of their need for electrical conductivity.

[0005]

In the case of a device that uses a battery as a power source, not limited to a lithium battery, the demands for weight reduction and nonflammability of the entire device are endless. Therefore, the lighter and safer the battery performance is, the more the user likes it.

However, there is a limit in production and handling even if the metal foil is thin. Further, although PTC elements, protection circuits, current interrupting mechanisms, etc. are provided as measures against equipment damage, no measures have been proposed to make the electrodes themselves that are the sources of fire non-combustible.

Therefore, an object of the present invention is to move away from the concept of a conventional current collector and to have a structure which is completely different from that of the conventional current collector, and which is effective in reducing the weight and incombustibility of the battery and the current collector. Another object is to provide a battery using a different current collector.

[0008]

In order to achieve the object, the current collector of the battery electrode plate of the present invention is characterized by being a layered body of a resin film and an electron conductive thin film. .

Since the current collector of the present invention has the resin film as the core, it is lighter than the current collector made of the metal foil having the same thickness. Moreover, since the thermal deformation temperature of many resins is lower than the ignition point of the organic electrolyte, even if heat is generated due to a short circuit, the resin film undergoes thermal contraction before the organic electrolyte such as the organic electrolyte solution or the polymer electrolyte ignites. It melts and the current is cut off. In this regard, in the case of metal foil, since the melting point is higher than the ignition point of the organic electrolyte, if heat is generated due to short-circuit, the organic electrolyte will ignite before the electrode temperature reaches the melting point of the metal foil, resulting in a dangerous state. Differently, the current collector of the present invention has a current interruption function. Although most of the resin is insulative, the current collector of the present invention has an electron-conductive thin film in close contact with the surface of the resin film, so that a current flows through the thin film.

As described above, since the current collector of the present invention is light and has the function of blocking current, the battery of the present invention using the current collector is also light and safe. Of course, it is not limited to organic electrolyte batteries, and there is no distinction between primary batteries and secondary batteries, alkaline batteries,
It goes without saying that weight reduction and safety can be expected in all batteries such as Ni-Cd batteries, Ni-HM batteries, and lead batteries. Further, when a conventional current collector made of a metal foil is cut into a predetermined size, burrs may be generated on the cut surface, which may cause a short circuit. The core is excellent in cutting property and does not generate burrs.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION In order to ensure the above-mentioned current interruption function, in the case of an organic electrolyte battery, a resin film is formed with a heat deformation temperature lower than the ignition point of the organic electrolyte of a battery using a current collector. Are preferred. There are two known methods for measuring the ignition point: a constant speed heating method and a constant temperature heating method. If you are uncertain which is realistic, it is safer to choose a lower measurement. Examples of the material of the resin film include polyethylene terephthalate (PET) and polypropylene (PP).
And the like.

As the thin film formed on the surface of the resin film,
Electroless plated Ni, Cu or evaporated Cu, A
Metals such as 1 are preferred. In particular, the thin film of the positive electrode current collector is preferably aluminum Al. 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, copper Cu or nickel Ni is particularly preferable as the thin film of the current collector of the negative electrode. Copper can be made extremely thin by vapor deposition to reduce the weight of the current collector. Moreover, copper is 3.7-3.9V.
It is experimentally known that it melts in the vicinity of vs. Li / Li ⁺ . Therefore, the proper discharge voltage is up to 3V, and below that is overdischarge. On the other hand, Ni does not melt up to 4.0 to 4.2 V vs. Li / Li ⁺ ,
Can discharge to 0V.

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

[0014]

【Example】

-Example 1-An example of the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view of an organic electrolyte battery of an example. 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 has a lithium cobalt composite oxide portion as an active material held on a current collector. The current collector was obtained by bringing a 2 μm thick aluminum thin film into close contact with the surface of a 20 μm thick PET film by vacuum deposition. The positive electrode plate 3 is 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 to prepare a paste, and then applying the paste to both surfaces of the current collector material , Made by drying.

The collector of the negative electrode plate 4 is made of PE having a thickness of 20 μm.
It was obtained by bringing a copper thin film having a thickness of 2 μm into close contact with the surface of the T film by vacuum vapor deposition. The negative electrode plate 4 has graphite 8 as a host material on both sides of its current collector.
6 parts and 14 parts of polyvinylidene fluoride as a binder were mixed to prepare a paste, which was applied and dried.

The separator 5 is a polyethylene microporous film. Further, the electrolytic solution contains ethylene carbonate: diethyl carbonate = 1: 1 containing 1 mol / l of LiPF6.
(Volume ratio).

The respective dimensions are 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 220 μm and a width of 31 mm. The negative electrode plate 4 is superposed in order and wound around the polyethylene core in an oval spiral shape.
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, this battery is sealed by laser welding a lid 7 to the case 6.

The completed battery weighed 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.

Example 2-As a collector of the negative electrode plate 4, a copper thin film PE was formed by vacuum deposition.
The thickness is 8μ by electroless plating instead of adhering to the T film.
A battery was manufactured under the same conditions as in Example 1, except that the nickel thin film of m was adhered to the PET film.

The completed battery weighed 17 g.
This battery was charged with a constant current of 1 CmA to a charge end voltage of 4.1 V and then discharged at 1 CmA, and it was discharged to a discharge end voltage of 0 V without any abnormality.

Comparative Example Comparison was made under the same conditions as in Example 1 except that a 20 μm thick aluminum foil was used as the collector of the positive electrode plate 3 and a 20 μm thick copper foil was used as the 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.

[0024]

As described above, according to the present invention, the battery can be made light and safe, which is useful as a component of a portable electronic device.

[Brief description of drawings]

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

[Explanation of symbols]

 1 organic electrolyte battery 2 electrode group 3 positive electrode plate 4 negative electrode plate 5 separator 6 battery case 7 case lid

Claims (10)

[Claims] 1. A current collector for holding an active material of an electrode or a host material in a battery, which is a layered body of a resin film and an electronically conductive thin film. Current collector. 2. The current collector for a battery electrode plate 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 current collector for a battery electrode plate according to claim 2, wherein the resin film has a heat distortion temperature lower than the ignition point of the organic electrolyte. 4. The current collector for a battery electrode plate according to claim 2, wherein the resin film is made of a thermoplastic resin such as polyethylene terephthalate (PET) or polypropylene (PP). 5. The current collector for a battery electrode plate according to claim 1, wherein the thin film is made of electroless plated or vapor-deposited metal. 6. The current collector for a battery electrode plate according to claim 1, wherein the layered body has two layers of a resin film and a thin film or three layers of a thin film, a resin film and a thin film in this order. body. 7. A battery using the current collector according to claim 1 for positive and negative electrodes. 8. The thin film of the current collector of the positive electrode is aluminum A
The battery according to claim 7, wherein the battery is 1. 9. The battery according to claim 7, wherein the thin film of the current collector of the negative electrode is copper Cu. 10. The thin film of the current collector of the negative electrode is nickel Ni.
The battery according to claim 7, which is