JPS60101870A - Thin battery - Google Patents

Abstract

PURPOSE:To obtain a thin battery having excellent internal resistance, gas barrier and corrosion resistance by using an amorphous metal as the positive current collector. CONSTITUTION:The positive current collector for a thin battery is formed by an amorphous metal. An amorphous metal has excellent properties such as a high corrosion resistance, a high strength, a high hardness, a high permeability and a low magnetic strain. However it is obtained only in tape-like form or linear form. Therefore it is difficult to manufacture an amorphous metal plate having such a smooth surface as that of the usual metallic plate. It is also difficult to perform hot working or machine working on an amorphous metal. Such an amorphous metal is used in ribbon-like form without performing any treatment after its manufacture. Concave and convex areas existing on the surface of an amorphous metal are rather favorable. Owing to these concave and convex areas, the contact area between a positive active material and the positive current collector increases and the internal resistance of the battery decreases.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a current collector in a thin battery.
In particular, it relates to the material of the current collector.

Prior Art of the Invention Stainless steel plates (or foils or nets), nickel plates (or foils or nets), titanium plates (or foils or nets), conductive plastic films, etc. have been studied as current collectors for thin batteries. . Each of these materials has its own advantages and disadvantages, and depending on the battery system, they may be fundamentally unusable.

For example, stainless steel and nickel cannot be used as current collectors for the positive electrode because they are severely corroded in Lecrancier type batteries that use manganese dioxide as the positive electrode mixture.

Titanium is a material that exhibits good corrosion resistance in this respect, but it is a scarce resource and expensive, making it difficult to use from a profitability standpoint. Carbon filler conductive plastic film can be said to be optimal in terms of price and corrosion resistance. However, it is difficult to obtain a conductive plastic film containing carbon filler that has both high mechanical strength and high electrical conductivity, and furthermore, there is still room for improvement in terms of chemical resistance and gas barrier properties. That is, in terms of chemical resistance, contact with chemicals increases the resistance value over time and causes a loss of flexibility. In terms of gas barrier properties, problems include deterioration of the active material due to evaporation of the electrolyte inside the battery and infiltration of atmospheric oxygen into the battery.

Therefore, it can be used as a current collector for thin batteries, and has excellent economic efficiency and corrosion resistance (
There has been a desire for a material that satisfies various conditions such as chemical resistance), electrical conductivity, and gas barrier properties.

OBJECT OF THE INVENTION The present invention has been made in response to the above-mentioned prior art,
The present invention provides a current collector that makes it possible to manufacture thin batteries with excellent internal resistance, gas barrier properties, corrosion resistance, etc. by using an amorphous metal.

Composition of the invention FIG. 1 is an explanatory diagram of a cross section showing an example of a thin battery.

Referring to the figure, from the top, the exterior film (31), negative electrode current collector (4), negative electrode active material (6), separator (10)
, positive electrode active material α, intermediate current collector (8), negative electrode active material (6), separator (10), positive electrode active material α2, positive electrode current collector (14), and exterior film (3) are layered. Formed °C
It is a thin battery with a stacked structure. The negative electrode active material (6) contains zinc, the positive electrode active material (one contains manganese dioxide, and the intermediate current collector (8) connects two unit batteries and serves as both a positive electrode and a negative electrode. It is a current collector.

In the present invention, the positive electrode current collector (and intermediate current collector) is made of an amorphous metal. Amorphous metals have excellent properties such as high corrosion resistance, high strength, high hardness, high magnetic permeability, and low magnetostriction, but on the other hand, they can only be obtained in the form of tapes or wires, and the surface is similar to that of ordinary metal plates. As such, it is difficult to manufacture it smoothly, and it is also difficult to heat or machine it. The present invention is characterized in that such amorphous metal can be used in the form of a ribbon as produced. Moreover, the unevenness on the metal surface is rather preferable, and increases the contact area between the positive electrode active material (12) and the positive electrode current collector (141).
This results in a decrease in internal resistance.

As a highly corrosion-resistant amorphous metal, Fe is used as an iron-based alloy.
-Cr-metallic alloy, Fe-Mo-metallic alloy,
Fe-Cr-Mo-metalloid alloy, nickel-based alloy as Ni-Cr-metalloid alloy, Ni-Mo-metalloid alloy, cobalt-based alloy, Co-cr-metalloid alloy,
A Co-Mo-semimetal alloy or the like can be used. In this example, a Fe-Cr-Mo based iron-based alloy was used.

Next, since amorphous metals are intended to be used in oxidizing atmospheres, such as manganese dioxide used as the positive electrode active material (12), the immersion experiment methods previously reported are insufficient, and the following An electrochemical acceleration experiment was conducted.

Shukaroy 242 (manufactured by Japan Heavy Chemical Industry Co., Ltd.) A,
Iron-based alloy (manufactured by Hitachi Metals, Ltd.) B was measured by two companies (
Table 1). The corrosion rate was calculated from the oxidation current. The oxidation potential of manganese dioxide in the Lecrancier battery is 0.
Since it is near 7 V vs -8 CE, the corrosion rate near this potential corresponds to the corrosion rate in an actual battery. According to this study, it was found that the amorphous alloy has almost the same corrosion resistance as titanium, and more than 400,000 times more corrosion resistance than stainless steel. Therefore, it is fully possible to use the amorphous alloy as a positive electrode current collector of a practical battery.

4- Effects of the invention By using an amorphous metal as the current collector, the corrosion resistance of the current collector can be significantly improved in an electrolyte solution in contact with a battery active material such as manganese dioxide, and the current collector can be used as a positive electrode and a thin layered battery. It can be used as an intermediate current collector, making it possible to manufacture thin batteries with low internal resistance, excellent gas barrier properties and mechanical strength.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a cross section of a stacked battery. (2) Thin battery (3) Exterior film (4
)...Negative electrode current collector (6)...Negative electrode active material (8)
...Intermediate current collector 00)...Separator (121...
・Cathode active material α (a)...Positive electrode current collector patent applicant Representative of Toppan Printing Co., Ltd. Kazuo Suzuki (Tato 1) 7- Figure 1 2

Claims (1)

[Scope of Claims] 1) A thin battery using a flat or foil-shaped current collector, characterized in that the positive electrode current collector is made of a highly corrosion-resistant amorphous metal. 2) The thin battery according to claim 1, wherein the amorphous metal also serves as a positive terminal.