JPH041468B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a battery, particularly a so-called nonaqueous electrolyte battery using a negative electrode made of a light metal such as lithium and a nonaqueous electrolyte.

FIG. 1 shows an example of a conventional battery of this type. First, a negative electrode terminal 10 made of metal, a positive electrode can 1
A power generating element 24 is hermetically housed in a battery case 16 consisting of a battery case 2 and a sealing gasket 14. The power generation element 24 is composed of a negative electrode 22 made of a light metal such as lithium, potassium, sodium, calcium, aluminum, magnesium, etc., a separator 20 impregnated with a non-aqueous electrolyte, and a positive electrode active material 18. The positive electrode active material is a metal oxide,
Main materials include halides and sulfides. This positive electrode active material 18 is preloaded into the positive electrode can 12 prior to battery assembly. Conventionally, the positive electrode can 12 is made of a chromium mesh, especially a chromium mesh that does not contain nickel. This is because if nickel is contained in the material of the positive electrode can 12, the nickel will gradually dissolve during storage of the battery, especially during storage at high temperatures, causing various harmful effects or inconveniences to the battery. . For this reason, conventionally, it has been impossible to use a metal containing at least nickel oxide as a material for the positive electrode can 12. Examples of materials commonly used in this type of battery include:
It was a chrome net that did not contain nickel, such as SUS-430 or SUS-434. Unfortunately, however, such nickel-free chrome nets
Compared to austenitic stainless steel containing nickel, it was significantly inferior in terms of workability such as can drawing. For this reason, in conventional batteries, although it is possible to prevent the harmful effects or inconveniences caused by the elution of nickel, it is difficult to process the positive electrode can of the battery case 16 using can drawing, etc., and this is a major cause of reduced battery productivity. At the same time, there were many defective products due to the difficulty in processing the positive electrode can 12.

This invention was made in view of the above-mentioned conventional problems, and its purpose is to improve the processability of the positive electrode can, such as can drawing, without causing any harm or inconvenience to the battery. Enables the use of metal materials including nickel to improve
As a result, it is an object of the present invention to provide a battery that can increase productivity, reduce the occurrence of defective products, and also improve performance.

To achieve the above object, the present invention provides a non-aqueous electrolyte battery as described above, in which the positive electrode can is made of nickel or chromium steel containing nickel, and the inner bottom surface of the positive electrode can is in contact with the positive electrode active material. is provided with a conductive film that covers the entire surface, and this conductive film contains a polymer compound and carbonaceous material, and contains 4 to 30 parts of solvent-soluble polybutene and graphite as a solid content. It is characterized by having a composition of 70 to 95 parts and 3 to 10 parts of acetylene black.

Hereinafter, preferred embodiments of the present invention will be described based on the drawings. Note that common or corresponding parts in each figure are indicated by the same reference numerals.

FIG. 2 shows one embodiment of a battery according to the invention. The battery shown in the figure is basically the same as the conventional battery described above. That is, a negative electrode 22 made of a light metal such as lithium, a separator 20 impregnated with a non-aqueous electrolyte, and a positive electrode active material 1.
The power generating element 24 consisting of 8 is housed in a sealed state in a battery case 16 consisting of a negative electrode terminal 16 which also serves as a part of the battery case, a positive electrode can 12 loaded with the above-mentioned positive electrode active material 18, and a gasket 14 as a sealing member. It is something. Here, the positive electrode can 12 is formed by can-drawing a thin metal plate punched into a predetermined outline shape, and the material of the metal thin plate is a chrome mesh containing nickel such as austenitic stainless steel, or nickel. A single metal is used. Along with this, the positive electrode can 1
The entire inner bottom surface in contact with the positive electrode active material 18 of No. 2 is a conductive film 2 made of a polymer compound and carbonaceous material.
Covered by 6. This conductive film 26 is formed in advance by coating or the like before loading the positive electrode active material 18 into the positive electrode can 12 . This conductive film 26 is a composition formed by mixing and dispersing a carbonaceous substance consisting of a mixture of graphite and acetylene black as a conductive substance into polybutene as a binder as a polymer compound. A conductive film made of such a composition is applied to the entire inner bottom surface of the cathode can 12 to a thickness of 20 to 50 microns, thereby interposing the film between the cathode active material 18 and the cathode can 12 and connecting the two. This will ensure that they are isolated from each other. In this case, the thickness of 20 microns to 50 microns is so thin that it can be ignored in relation to the overall size of the battery, and therefore there is no fear that the effective power generation capacity of the battery will be impaired. Rather, such a conductive film 26 connects the positive electrode active material 18 and the positive electrode can 12.
By intervening between them, the state of electrical contact between the two can be greatly improved and stabilized, which has the effect of improving discharge performance such as reducing internal resistance. You will be able to get it. At the same time, the conductive film 26 also acts as a protective film to prevent the nickel contained in the material of the positive electrode can 12 from melting, especially during high-temperature storage. Even if the battery is constructed with a chrome mesh containing the same, it does not cause any harm or inconvenience to the battery.

By the way, to describe the above-mentioned conductive film 26 more specifically, its composition ratio is 4 parts to 30 parts of polybutene and 70 parts to 95 parts of graphite as solid content.
parts, and 3 to 10 parts of acetylene black. When the polybutene content exceeds 30 parts, both elasticity and adhesion are good, but the electric resistance value inherent to the conductive film becomes large, and when it is below 4 parts, the function of the binder is impaired. To form the conductive film 26 having the above composition, polybutene is dissolved in benzene or the like,
Next, a mixture of graphite and acetylene black is mixed and dispersed in this, and this mixed solution is added to the positive electrode can 12.
All you have to do is apply it to the entire inside bottom surface and let the benzene evaporate. The thickness of the film 26 obtained in this case is about 20 to 150 microns, but this thickness can be adjusted as appropriate by adjusting the dilution rate, coating conditions, etc.

Now, let us now examine a high-temperature storage test of battery A according to the present invention provided with the above-mentioned conductive film 26 and conventional battery B, which has exactly the same shape but uses a cathode can 12 that does not contain nickel. At the end of the day, almost no difference was observed due to the difference in the material of the positive electrode can.

Furthermore, when we investigated the occurrence rate of defects that were recognized to be caused by poor processing of the positive electrode can for 1,000 samples each, we found that while battery A had zero defects, battery B had 13 defects. The occurrence of defects was observed.

As described above, the battery according to the present invention uses nickel or nickel-containing chromium steel, which has excellent workability, as the positive electrode can material without making any major changes to its basic configuration, without causing any disadvantages or disadvantages. This prevents performance deterioration especially when stored at high temperatures, reduces the occurrence of defects due to poor processing of the positive electrode can, increases productivity, and improves the quality of positive electrode activation. It is also possible to improve the discharge performance by making the electrical contact between the substance and the positive electrode can better and more stable.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view showing an example of a conventional battery;
The figure is a sectional view showing one embodiment of a battery according to the present invention. 10... Negative electrode terminal, 12... Positive electrode can, 14...
Gasket, 16... Battery case, 18... Positive electrode active material, 20... Separator, 22... Negative electrode, 2
4... Power generation element, 26... Conductive film.

Claims (1)

[Claims] 1. A negative electrode terminal comprising a negative electrode made of a light metal such as lithium, a non-aqueous electrolyte, and a positive electrode active material, and which also serves as a part of a battery case, a positive electrode can loaded with the positive electrode active material, and a sealing member. In a battery in which the power generation element is housed in a battery case, the positive electrode can is made of nickel or chromium steel containing nickel, and the inner bottom portion of the positive electrode can that comes into contact with the positive electrode active material includes: A conductive film covering the entire surface is provided, and this conductive film contains a polymer compound and carbonaceous material, and has a solid content of solvent-soluble polybutene 4 to 4.
30 parts, graphite 70-95 parts, acetylene black 3-10 parts
A battery characterized by having a composition of: