JPS62136760A - Manufacture of electrode for battery - Google Patents

Abstract

PURPOSE:To improve the flexibility of an electrode as well as to make its winding ever so easy, by letting it pass through a leveler device after pressurizing the electrode filled up with an active material. CONSTITUTION:An active material is filled up in an expandable metal and then pressurizing operation takes place for improving the bulk capacity density. Next, the electrode (a) obtained in this way is passed through a leveler device (b) and leveler treatment takes place. With this constitution, flexibility in the electrode (a) is improved, and its winding comes so easy and, what is more, damage or breakage of the electrode at the time of winding is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing an electrode used in a secondary battery such as a ninkel cadmium storage battery, and more specifically to a method for manufacturing an electrode for use in a secondary battery such as a nickel cadmium storage battery. The present invention relates to battery electrodes.

Conventional secondary battery electrodes have the advantage of filling a metal cylindrical bag-like or lattice-like support with an active material, and that the metal sintered body can be made large, but they do not have high discharge characteristics. It has the disadvantage of being bad. In addition, the latter method using a metal sintered body support has the advantage of excellent high rate discharge characteristics, but has the disadvantage of a small filling capacity. In order to improve both of these drawbacks, battery electrodes have recently been proposed in which a metal foam having a continuous three-dimensional network structure with high porosity is used as a support. This method of filling active material into foamed metal produces an electrode suitable for high capacity and high rate discharge.

However, a nickel positive electrode using a foamed metal has a problem in that although the foamed metal has high porosity and can have a high capacity, the high porosity makes the electrode plate low in strength.

Problems to be Solved by the Invention This is a particular problem when winding for battery group construction. That is, since the electrode strength is low, the electrode plate is likely to be bent during winding, resulting in a decrease in battery capacity, or the bent portion of the electrode plate may damage the separator, resulting in leakage failure. As a method to prevent this, methods have been proposed such as inserting a reinforcing body into the foam metal (Utility Model Application No. 53-62630) and improving the strength of the electrode plate. There were problems in terms of cost, etc. The present invention aims to solve the problem of electrode damage during winding.

Means to Solve the Problems In order to solve the above problems, the present invention improves the flexibility of the electrode by pressurizing the electrode filled with the active material and then passing it through a leveler device. This facilitates winding and reduces damage and bending of the electrode during winding, thereby improving battery characteristics.

Function: In an electrode in which a foamed metal is filled with an active material, pressure processing is generally performed after filling the active material in order to increase the filling degree. However, increasing the packing density generally reduces the flexibility of the plate. When aiming at high capacity using foamed metal, it is necessary to increase the porosity of the foamed metal, but as described above, the strength of the electrode decreases.

When such electrodes with low flexibility and strength are wound together with a separator and a negative electrode to form a group, bending of the electrodes,
Otherwise, the problem of breakage is likely to occur. However, by passing the pressurized electrode through a leveler device, the flexibility of the electrode is improved, winding becomes easier, and the above-mentioned problems are less likely to occur.

Example An embodiment of the present invention will be described below with reference to the drawings.

A foamed metal with a thickness of about 2mm and a porosity of about 96% is filled with an active material mainly composed of nickel hydroxide, and then 3oOKP
Pressure processing was performed at a pressure of /cJ. Next, using an electrode A which is not leveled by the conventional method and an electrode B in which the electrode A after pressurization is passed through a leveler device equipped with a large number of meandering rolls as shown in Fig. 1, the SC size is determined. A sealed nickel-cadmium storage battery was constructed and the battery characteristics were compared. Regarding battery characteristics, a comparison of standard capacity and high rate discharge characteristics was performed to detect electrode bending. High rate discharge is
A comparison was made using the ratio of the discharge capacity equivalent to 0.20 and the discharge capacity equivalent to 3C. Depending on the degree of bending in the electrodes, some have a capacity as low as 0.20, while others have a high rate discharge capacity of about 3C capacity. FIG. 2 is a comparison of standard capacity (0.2G discharge capacity) between Battery A manufactured by a conventional method and Battery B of the present invention. In FIG. 2A, there is no visible decrease in capacity due to the bending of the electrode, while in B, the capacitance is within the designed range. Figure 3 also shows 30
FIG. 3 is a diagram showing a comparison of discharge capacity ratios. In the conventional battery shown in FIG. 3A, a decrease in the discharge capacity ratio is observed, which is thought to be due to the bending of the electrodes, whereas in the battery B of the present invention, this is not observed.

Furthermore, when we investigated the leakage rate of battery A made by the conventional method and battery B made by the present invention, we found that the leakage rate of A was 0.
．． While it is about 5%, the streetcar B according to the present invention has a
．． 08%, indicating a significant reduction in the leakage rate.

Effects of the Invention As described above, according to the present invention, the problems encountered when winding a group of electrodes using foamed metal are improved, and stable battery characteristics can be obtained.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the leveler device used in the present invention, Figure 2 is a schematic diagram of the leveler device used in the present invention.
Figures A and B are diagrams showing batteries constructed using a conventional method and the distribution of capacity ratios. a... Electrode, b... Leveler device. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure α-1qiao b-pτ Ray elephant, 1 Figure 2 (c) (8) Figure 3

Claims (1)

[Claims] A method for manufacturing a battery electrode in which a foamed metal with a continuous three-dimensional network structure is filled with an active material. A method for producing a battery electrode, comprising the step of passing the electrode through a leveler device to make it flexible after the pressurizing step.