JPH02250257A - Paper battery - Google Patents

Abstract

PURPOSE:To provide a paper battery having a stable sealing, wherein the sealing strength will never drop even when stored at a high temp. by subjecting those surface portions of a pos. electrode terminal plate and neg. electrode terminal plate, which contact the sealing, to chromate process. CONSTITUTION:At least those surface portions of terminal plates 1, 5 which contact a sealing 6 undergo a chromate process, i.e., a process using solution chiefly containing chromate or dichromate. A sealing material 6 is fusion welded to the peripheries of a pos. electrode terminal plate 1 and neg. electrode terminal plate 5 after said processing, and a lithium neg. electrode 4, separator 3, and pos. electrode black mix 2 as components of battery are put one over another on the surface of neg. electrode terminal plate 5 on its sealing material affixed side. Further the pos. electrode terminal plate 1 is put on this pos. electrode black mix 2 with the surface on the sealing material affixed side facing the black mix, followed by application of pressure and heat from the outside, and thus the peripheries of the terminal plates are fusion welded with the sealing material 6 to achieve sealing. This provides a paper battery with stable sealing with no risk of deterioration of sealing strength even after storage at high temp.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a paper battery constructed by sandwiching a flat, thin power generation element between terminal plates that also serve as terminals.

<Prior Art> Paper batteries are used as power sources for IC cards, thin electrical devices, and the like. For example, in a paper lithium battery, a power generating element in which a positive electrode mixture, a separator, and a lithium negative electrode are sequentially stacked is sandwiched between a thin flat positive electrode terminal plate and a negative electrode terminal plate that also serve as electrode terminals.

By the way, the thickness of this paper battery is at most Q, 5m.
Since it is as thin as 1.5 m, its sealing structure differs from the type used in button-type alkaline batteries, in which an insulating gasket is compressed between terminal plates, and generally,
A frame-shaped sealant made of an insulating material such as polyolefin resin is placed around the periphery of the positive terminal plate and the negative terminal plate, and the periphery of the battery is heated and pressurized to seal the periphery of the terminal plate with the sealant. A structure is used in which the battery is sealed by heat fusion.

<Problems to be Solved by the Invention> However, in this structure in which the peripheral edge of the terminal plate is sealed by heat-sealing with a sealing material, the sealing strength tends to decrease. For example, when a battery is stored at a high temperature of about BO° C., the sealing performance decreases due to a decrease in the sealing strength between the sealing material and the terminal board.

Therefore, for example, as described in Japanese Patent Application Laid-Open No. 57-138759, the surface of the terminal board that comes into contact with the sealing material is treated with a mixed solution of sulfuric acid and oxalic acid to make this surface rough.
Alternatively, as disclosed in JP-A-82-188183, a method has been proposed in which the sealing strength between the sealing material and the terminal plate is improved by forming an oxide film on the surface of the terminal plate.
This is still insufficient, and it is not possible to obtain the sealing strength required for practical use.

An object of the present invention is to provide a paper battery having a stable sealing portion without decreasing sealing strength even during high-temperature storage.

Means for Solving the Problems> The paper battery of the present invention has a power generation element sandwiched between a pair of terminal plates made of thin metal plates, and the peripheral edges of these terminal plates are sealed with an insulating sealing material. In the paper battery constructed by the present invention, the gist is to use a terminal plate having at least the surface that comes into contact with the sealing material treated with chromate.

The above-mentioned chromate treatment refers to treatment with a solution containing chromic acid or dichromate as a main component. By immersing the object to be treated in this solution, a 0.5μ
A rust-preventive film (chromate film) with a thickness of less than m can be formed on the surface of the object to be treated.

Examples of such ROM compounds include chromic acid, potassium chromate, sodium chromate, potassium dichromate, and sodium dichromate.

Further, as the sealing material, materials such as silicon resin, Teflon resin, or polyolefin resin can be used.

Furthermore, the positive terminal plate is made of stainless steel FF14i.

A nickel-plated stainless steel mesh plate or the like can be used for the outer surface of the battery, and a nickel steel plate, a stainless steel plate, a nickel-plated stainless steel plate, or the like can be used for the negative terminal plate.

In addition, for example, by performing chromate treatment on both sides of each terminal plate, there is an advantage that the chromate coating formed by this treatment increases the gloss of the terminal plate and improves the appearance of the battery.

Effect> It has been found that by chromating the surfaces of the positive terminal plate and the negative terminal plate that come into contact with the sealing material as described above, the sealing strength between the terminal plate and the sealing material is significantly improved.

This is because by chromating the terminal plate, a functional group is added to the surface of the terminal plate, and this functional group and the functional group of the sealing material are bonded (possibly a covalent bond), resulting in the sealing strength being increased. It seems to be for improvement.

It is also believed that the chromate treatment improves the corrosion resistance of the terminal board and helps maintain the sealing properties between the terminal board and the sealing material over a long period of time.

<Example> Examples will be described below.

Potassium dichromate zoog/Ω, sulfuric acid 5 g#! A positive terminal plate and a negative terminal plate made of stainless steel were immersed in a mixed solution heated to 40°C for 10 minutes to perform chromate treatment, and a chromate coating with a thickness of approximately 0.5 μm was applied to these terminal plates. Formed.

Note that the positive electrode terminal plate used was one whose central portion was formed into a convex shape by drawing.

Next, frame-shaped sealing materials made of modified polyethylene were heat-sealed L7 to the peripheral edges of the treated positive electrode terminal plate and negative electrode terminal plate, respectively.

Thereafter, a lithium negative electrode, which will serve as a battery element, a separator soaked in electrolyte, and a positive electrode mixture are sequentially laminated on the side of the negative electrode terminal plate on which the sealing material is fused, and then the positive electrode terminal plate is placed on top of this positive electrode mixture. were stacked one on top of the other with the sealing material fused side facing the positive electrode mixture side.

Then, a predetermined pressure and heat are applied from the outside to the peripheral edges of the terminal plates, and the peripheral edges of the terminal plates are thermally fused using a sealing material to seal the battery, resulting in a thickness of 0.5 mm as shown in the attached drawings.
A lithium paper battery (product of the present invention) with a width IB of 5 m1w and a length of 84.5 mm was produced. In the figure,
1 is a positive electrode terminal plate, 2 is a positive electrode mixture, 3 is a separator, 4 is a lithium negative electrode, 5 is a negative electrode terminal plate, 6 is a sealing material, and 7 is a chromate coating.

On the other hand, using a positive terminal plate and a negative terminal plate that were not subjected to chromate treatment, the other things were the same, and the thickness was 0.5n.
A lithium paper battery (conventional product) with a width of 1B, 5 mm, and a length of 34.5 mm was manufactured.

For these batteries, when stored at a temperature of 60°C for 120 days, the initial, 40th, 80th, and 120th
The sealing strength after each day was measured. The results are shown in Table 1. In addition, in this result, the sealing strength is J
Peel strength according to IS K 6854. Further, in this table, each sealing strength is shown as a value when the initial sealing strength of the conventional product is set as 100.

Table 1 From the results, it can be seen that the sealing strength of the product of the present invention hardly decreases even after 120 days, and the sealing strength is generally considerably higher than that of the conventional product. On the other hand,
The conventional product had a large decrease in sealing strength, and after 120 days of storage, the sealing strength was reduced to half.

<Effects of the Invention> As described above, the present invention provides a paper battery that does not deteriorate the sealing strength between the terminal board and the sealing material even after high-temperature storage and has a sealing portion that is stable over a long period of time. be able to.

[Brief explanation of drawings]

The accompanying drawing is a cross-sectional view of a battery according to an example. DESCRIPTION OF SYMBOLS 1... Positive electrode terminal plate, 5... Negative electrode terminal plate, 6... Sealing material, 7... Chromate coating. Substitute Hitomi Matoyuki Male

Claims (1)

[Claims] 1. In a paper battery constructed by sandwiching a power generation element between a pair of terminal plates made of thin metal plates and sealing the peripheral edges of these terminal plates with an insulating sealing material, the terminal plates include at least A paper battery characterized in that the surface that comes into contact with the sealing material is subjected to monochromate treatment.