JP3154483B2 - Battery - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to batteries, and more particularly to batteries having improved current collectors.

[Prior Art] In general, it is known to use an expanded metal for a current collector of a battery, especially a non-aqueous electrolyte battery (Japanese Patent Application Laid-Open No. 57-157).
11473, JP-A-61-151975).

Expanded metal is a mesh-like material produced by cutting a metal sheet into perforations and pulling it, and is particularly frequently used in lithium primary batteries and the like. According to this manufacturing method, if the thickness of the metal sheet is too small, the streaks may be cut in places, or the whole may be cut.
The thickness on the order of μm was the limit. The material is titanium,
There are various types such as aluminum and stainless steel, but stainless steel is most preferable in terms of mechanical strength, corrosion resistance and cost.

Positive, although the negative electrode consists of active material and the current collector, the battery (e.g., MnO ₂ positive electrode, a non-aqueous electrolyte primary of Li negative electrode reducing the thickness of each pole is formed of particular electrodes spiral (spiral) structure Batteries and secondary batteries).

The reason is that if the winding diameter of the spiral electrode is constant by making each electrode thinner, the winding length can be made longer, so that the area of the positive and negative electrodes facing each other becomes large, and large current discharge and large current charge Is possible. Actually, the solid active material can be pulverized by pulverization or the like, so that it does not become a factor in determining the thickness. Was desired. To simply make the current collector thin, there is a method of using a metal foil or the like. It has the drawback that it cannot be charged and causes an increase in internal resistance.In addition, there are also problems that the cost is high and the amount of binder needs to be increased because of poor adhesion to the current collector. .

[Problems to be Solved by the Invention] An object of the present invention is to use a thin stainless steel expanded metal having a low cost, a good current collecting property, a high corrosion resistance and a high mechanical strength as an electrode current collector in view of the above situation. It is an object of the present invention to provide a battery capable of large current discharge (high current charge / discharge in the case of a secondary battery).

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have made intensive studies on the thinning of expanded metal made of stainless steel. Expanded metal can be made with a thickness of SUS304, 430, 316, etc., and those that have been annealed can find that an expanded metal can be made with a thickness of 25 to 50 μm. .

That is, the present invention is a battery in which at least one of the positive electrode and the negative electrode contains an expanded metal made of stainless steel SUS430H having a thickness of 50 μm or less.

As described above, the battery of the present invention basically uses a stainless expanded metal of 50 μm or less as a current collector for at least one of the two electrodes in a battery including a positive electrode, a negative electrode, and an electrolyte. .

The material of the stainless steel to be used is preferably SUS430H. When this is used, expanded metal of 50 μm or less can be used by a usual method. Also, SUS304,
When using 430, 316, for example, 650-700 in an electric furnace
After heating at 30 ° C. for 30 minutes, the power is turned off, and the material is annealed by gradually cooling to room temperature. Similarly, expanded metal of 50 μm or less can be obtained.

In the battery of the present invention, known materials such as a positive electrode and a negative electrode active material, an electrolytic solution, and a separator other than the current collector can be used.

That is, the positive electrode and the negative electrode generally include an active material and a current collector. As the active material, for example, MnO ₂ , V _{2
O 5, TiS, MoS 2,} HgO, Ag 2 O, O 2, (CF) n, CuO, SOC
l ₂ , PbO ₂ , NiOOH, S, Br ₂ , FeS ₂ , activated carbon, polyaniline, polypyrrole and the like. In the negative electrode, Zn, Li, P
b, Cd, Fe, H ₂ , Na, Al, graphite, and an organic fired body such as pitch coke. The current collector used in the battery of the present invention is applied to an electrode using a solid material as an active material among these active materials.

Examples of the electrolyte include an aqueous solution of ZnCl _{2, an} aqueous solution of KOH, an organic solvent solution of a Li salt, and an aqueous solution of H ₂ SO ₄ . Examples of the separator include a microporous polypropylene film and a microporous polyethylene film, a polyamide nonwoven fabric, and paper.

As a method of preparing an electrode using the expanded metal, for example, when MnO ₂ is used as a positive electrode active material,
A predetermined amount of O ₂ powder, a conductive material such as carbon black or graphite, and Teflon dispersion may be kneaded and applied to the expanded metal, and the thickness may be made uniform with a pressure roller or the like. When used as a Li negative electrode, a lithium foil having a predetermined thickness may be superimposed on the expanded metal and integrated by pressing. Other active materials may be similarly treated.

The battery of the present invention may have a spiral structure by laminating the above-described positive electrode, separator, and negative electrode, or may have a sheet-type or coin-type battery while being superposed. Further, a plurality of layers may be stacked to form a so-called gum (square) battery.

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1 In FIG. 1, a = 1 mm, b =
An expanded metal of 0.5 mm and c: 0.2 mm was produced.

80 parts by weight of heat-treated electrolytic manganese dioxide, graphite 10
Parts by weight, 10 parts by weight of 60% Teflon dispersion are thoroughly kneaded and applied to both sides of the expanded metal.
A positive electrode having a size of 45 mm, a length of 40 cm, and a thickness of 80 μm was prepared.

An electrode having a spiral structure was prepared using a lithium foil having a width of 45 mm, a length of 40 cm and a thickness of 50 μm as a negative electrode together with a polypropylene separator, and stored in an AA battery can. Using a mixture of 50 parts by weight of dimethoxyethane and 50 parts by weight of propylene carbonate in which LiBF ₄ was dissolved at a concentration of 1 mol / as an electrolytic solution, an AA lithium battery was prototyped.
The short-circuit current value of this battery was 22.5A.

Comparative Example 1 An expanded metal having the same shape as that of Example 1 was made of SUS430H having a thickness of 300 μm.

Heat treated electrolytic manganese dioxide, graphite, Teflon dispersion, width 45mm, length 40c as in Example 1.
A spiral electrode having a width of 45 mm, a length of 40 cm, a thickness of 50 μm, a lithium foil and a polypropylene separator was prepared, but could not be accommodated in an AA battery can. Both the positive and negative electrodes could be stored by setting the length to 20 cm.

Using the same electrolytic solution as in Example 1, an AA lithium battery was prototyped. The short-circuit current value of this battery was 5.2A.

[Effects of the Invention] As described above, by realizing a thinner current collector according to the present invention, the battery itself can be made thinner, and in other spiral batteries, the winding diameter is reduced. When it is constant, the positive and negative electrode facing areas can be significantly increased, so that a large current discharge or a large current charge / discharge becomes possible.

[Brief description of the drawings]

FIG. 1 is a view for explaining dimensions of expanded metal used in Examples.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01M 4/74

Claims (1)

(57) [Claims] 1. A battery wherein at least one of a positive electrode and a negative electrode contains an expanded metal made of stainless steel SUS430H having a thickness of 50 μm or less.