JPH0217911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in nickel electrode plates used in nickel, zinc batteries, nickel, cadmium batteries, etc. More specifically, the present invention relates to improvements in nickel electrode plates used in nickel, zinc batteries, nickel, cadmium batteries, etc. In a nickel electrode plate manufactured using an adhesive resin, the present invention aims to reduce the content of the adhesive resin to provide a nickel electrode plate with high mechanical strength and excellent life characteristics and electrical properties. .

Conventionally, nickel electrode plates are made by sintering nickel powder into a porous body with a porosity of 80 to 90% in a reducing atmosphere to form a substrate, which is then impregnated with nickel nitrate using a thermochemical or electrochemical method. It is obtained through the combined use of filling, steam pyrolysis, alkali treatment, etc. Nickel electrode plates manufactured by this method have the characteristics of little deterioration due to charge/discharge cycles and low internal resistance, but on the other hand, the drawback is that the manufacturing process is complicated and the manufacturing cost is significantly high. It was hot. To improve this drawback, electrode plates have recently been obtained by pressing a mixture of a nickel hydroxide active material, a conductive material such as graphite, and a resin as a binder onto a current collector. There is something. This electrode plate is inexpensive due to its simple process, but because it uses a non-conductive resin, the plate resistance is large and its electrical characteristics are poor. Therefore, by reducing the amount of resin, the resistance decreases, but at the same time, the mechanical strength also decreases, the active material tends to fall off, and the life characteristics of the battery are shortened.

The present invention has been made as a result of extensive research in view of the current situation, and as a result has discovered an electrode plate that uses a small amount of binder resin, does not reduce mechanical strength, and has excellent electrical properties. That is, in the present invention, in an electrode plate formed by pressing a mixture of a nickel active material, a conductive material, and a binder resin on a current collector, a relatively large amount of binder resin is applied to the portion that contacts the current collector. It is characterized by containing a relatively small amount of binder resin in other parts.

In the present invention, a relatively large amount of binder resin, e.g.
The reason why it is formed with a mixture containing 15wt% is
It was confirmed that the main cause of electrode plate deterioration and active material falling off is separation of the current collector and active material or conductive material, and that the part of the electrode plate that requires the strongest adhesiveness is the current collector. It was discovered that this is the part that is in contact with the body. Therefore, by forming a layer near the current collector that contains a relatively larger amount of resin than other parts, the contact between the current collector and the active material or conductive material is strengthened, and this area is Mechanical strength increases. In other parts, the amount of resin is relatively low, for example, 5~
By forming a small amount, such as 10 wt%, the resistance is small and the electrical characteristics are good.

Next, embodiments of the present invention will be described based on the drawings.

Example 1 A mixture A is prepared by kneading 55 parts by weight of nickel hydroxide powder, 35 parts by weight of graphite as a conductive material, 5 parts by weight of nylon powder as a binder resin, and 5 parts by weight of cobalt hydroxide as an additive.

Next, 50 parts by weight of graphite, 40 parts by weight of nickel powder, and 12 parts by weight of nylon powder were kneaded to form a mixture B.
shall be.

As shown in FIG. 1, 10 parts of mixture B is uniformly spread on both sides of the perforated nickel plate 1 to form a large resin layer 2, and then 90 parts of mixture A is filled to form a small resin layer 3. The electrode plate A of the present invention was obtained by forming and pressing under pressure at 120°C.

Further, as shown in FIG. 2, 10 parts of the mixture B was uniformly spread on both sides of the nickel plating perforated plate 1 to form a large resin layer 2, and then 80 parts of the mixture A was filled to form a small resin layer 3. Further, 10 parts of mixture B was filled to form a large resin layer 2' to obtain electrode plate B of the present invention.

Note that this electrode plate can make the mechanical properties of the electrode plate surface stronger and is effective in preventing the active material or conductive agent from falling off.

In addition, for comparison with the electrode plate of the present invention, a conventional electrode plate was prepared by filling 100 parts of Mixture B onto a current collector.

A nickel cadmium battery was constructed by combining the thus obtained electrode plate A of the present invention and the conventional electrode plate with a sintered cadmium electrode plate, and the discharge curve was measured as shown in Fig. 3. It can be seen that the invention electrode plate is excellent.

Further, when electrode plate deterioration was measured for the electrode plate A of the present invention and the conventional electrode plate, the conventional product showed significant deterioration around 100 cycles, but the present invention product began to deteriorate after 200 cycles, showing a significant difference.

As described in detail above, the present invention has high mechanical strength and excellent electrical properties, and is extremely useful as an industrial value as it can be used for a long period of time.

[Brief explanation of drawings]

Figures 1 and 2 show one example of the nickel electrode plate of the present invention.
FIG. 3, which is a sectional view showing an example, is a relationship curve diagram between battery voltage and discharge time for a nickel electrode plate of the present invention and a conventional nickel electrode plate. 1... Current collector, 2... Small amount of resin layer, 3... Large amount of resin layer.

Claims (1)

[Claims] 1. In an electrode plate formed by pressing a mixture of a nickel active material, a conductive material, and a binder resin onto a current collector, the portion that contacts the current collector contains a relatively large amount of binder resin. A nickel electrode plate characterized in that other parts are formed with a relatively small amount of binder resin.