JPH04206366A - Flat battery - Google Patents

Abstract

PURPOSE:To prevent the aggravation of the battery performance by laminating a flat positive electrode active material and a negative electrode active material through a solid electrolyte, covering these generating elements with a collector, divisionally forming the positive electrode active material on the collector, and sealing the peripheral part by a sealing material. CONSTITUTION:On a stainless foil used as both a battery sheath and a collector 1, an aqueous solution of vanadium pentoxide which is a positive electrode material 2 is finely applied by means of screen printing, dried and heated. For example, a 1,2-dimethoxyethane(DME) solution of a polyphosphadine derivative in which 1mol/l of lithium perchlorate is dissolved is applied thereon by means of screen printing, and the DME is evaporated to form a solid electrolyte 3. A metal lithium foil is stuck thereon as a negative electrode active material 4, and further covered with the stainless foil of a collector 1', and the peripheral part is thermally fused by a sealing material 5 such as a modified polyethylene resin and sealed. Thus, the aggravation of the battery performance can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a flat battery having a structure in which electrode active materials are laminated.

(Prior Art) In response to the recent demand for thinner batteries, flat (sheet-shaped) batteries have been developed and are used as power sources for devices such as IC cards. Although flat batteries use flat active materials, there are significant benefits and demands for making the batteries even thinner. Therefore, it has been proposed that batteries can be made even thinner by applying a paste, slurry, or colloidal positive electrode active material to a foil current collector and drying it to form a thin film. .

(Problem to be solved by the invention) However, in conventional flat batteries, lithium or lithium alloy is often used as the negative electrode active material, and in such cases, in order to remove water from the positive electrode active material, the positive electrode It is necessary to heat-treat the active material at an appropriate temperature. When a positive electrode active material coated together with a foil current collector (usually metal foil) is heat-treated, the foil current collector may curve or the positive electrode active material may bend due to the difference in thermal expansion coefficient between the current collector and the positive electrode active material. The substance may peel off, which inevitably causes problems during battery production and deterioration of battery performance.

(Means for Solving the Problems) Therefore, the present invention is characterized in that a positive electrode active material is formed on a foil-like current collector in pieces.

(Function) By having the above characteristics, the foil-like current collector can be curved,
Peeling of the positive electrode active material can be reduced, and deterioration of battery performance can be prevented.

(Example) Next, an example of the present invention will be described. FIG. 1 is a sectional view of a flat battery of the present invention.

A vanadium pentoxide aqueous solution (sol or gel), which is the positive electrode active material 2, is coated on a stainless steel foil serving as the battery exterior and the current collector 1 in small pieces by a method such as screen printing, and then dried and heated. From above, 1moi! , /j2
A solution of a polyphosphazene derivative in 132-dimethoxyethane (DME) in which lithium perchlorate is dissolved is applied by a method such as screen printing, and then the DME is evaporated to form the solid electrolyte 3. A metallic lithium foil is pasted on top of it as the negative electrode active material 4, and then covered with stainless steel foil as a current collector, and the periphery is heat-welded and sealed with a sealing material 5 such as modified polyethylene resin. .

FIG. 2 shows a solid electrolyte 3 similar to that in FIG. On top of that, metal lithium foil is pasted as the finely divided negative electrode active material 4, and then the stainless steel foil of the current collector 1' is covered from above to form the peripheral edge and the dividing boundary of the finely divided power generation element. A sealing material 5 such as modified polyethylene is placed in the portion.

FIG. 3 shows the life of the flat battery cycle of the present invention obtained in this manner. The horizontal axis represents the number of subdivisions of the active material, and the vertical axis represents the lifespan ratio with the lifespan of the conventional product set to 1.

For comparison, the active material weight and apparent surface area of the product of the present invention and the conventional product were made the same. Furthermore, the lifespan was determined to have come to an end when the capacity reached one-half of the initial capacity. As you can see from the figure,
As the number of subdivisions increases, the lifespan increases, reaching approximately twice the lifespan of conventional products. This effect was particularly noticeable during high rate discharge.

The flat battery of the present invention has a large capacity despite being small and thin. Furthermore, when a solid polymer electrolyte is used as the electrolyte, the battery can be bent and the bent shape can be maintained. Therefore, the degree of freedom in designing the battery space within the device increases, and the space for electronic components within the device can be used effectively.

(Effects of the Invention) As described above, the present invention prevents peeling of the positive electrode active material during drying and heating dehydration treatment and curvature of the positive electrode plate by forming the active material in pieces on the current collector. Therefore, deterioration of battery performance due to these causes can be prevented.

Furthermore, in the structure shown in Fig. 2, for example, between x and x',
By cutting between y and y', it is possible to easily produce a flat battery of any shape and capacity, and it also has the advantage of being able to rapidly manufacture the smallest unit of flat batteries, which is of great value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of the invention, and FIG. 2 is a sectional view showing another embodiment of the invention.

Claims (3)

[Claims] (1) In a flat battery in which a flat positive electrode active material and a negative electrode active material are laminated via a solid electrolyte, and these power generation elements are covered with a current collector, at least the positive electrode active material is layered on the current collector. A flat battery characterized by being formed in sections and having a peripheral portion sealed with a sealing material. (2) The flat battery according to claim (1), wherein the positive electrode active material is printed in segments on the current collector. (3) The flat battery according to claim (1), wherein a sealing material is disposed at a dividing boundary portion of the active material formed on the current collector.