| 摘要 |
1511015 Secondary batteries having a Zn electrode DEUTSCHE AUTOMOBIL GmbH 7 May 1975 [9 May 1974] 19219/75 Heading H1B A rechargeable cell 1 comprises a zinc cathode 4, a metal oxide, air or oxygen anode 2, an alkaline electrolyte 7, an auxiliary electrode 8 which is not permanently connected conductively to the anode and cathode and which serves both as an auxiliary electrode for after-discharge of the zinc electrode and as a dendrite barrier, and separators 6, 10. After-discharging is effected when a decrease in the capacity of the cell is noticeable; the zinc and auxiliary electrodes are short-circuited. The auxiliary electrode has a surface coating made of an electrocatalyst for hydrogen evolution, ensuring a slight hydrogen over-voltage. The anode may be nickel, manganese, mercury or silver oxides, or air or oxygen (Fig. 2, not shown). The electrolyte 7 may be KOH and/or NaOH, preferably with the addition of silicates and phosphates. The zinc cathode 4 may have a current collector framework consisting of copper, iron, nickel, silver, or alloys thereof; cadmium- or silver-plated copper in the form of plates, nets or expanded metal is preferrred. The auxiliary electrode 8 consists of porous conductive material in the form of net, perforated sheet or sieve plate with circular, rectangular or hexagonal orifices and on open area of 20-60%. The material may be copper, iron or nickel, preferably nickel or nickel-plated copper or iron. The electrode coating can be finelydivided platinum or palladium, Raney nickel, titanium-nickel alloys or X-ray amorphous nickel boride. Separators 6, 10 are microporous, e.g. of polypropylene or polystrene. In a modification the electrolyte may be circulated. |
