PURPOSE: To eliminate ineffective charge, to shorten charge time, and to manufacture a silver peroxide plate without wasting power by carrying out discharge for a fixed time after confirming attainment to the final level voltage of silver peroxide when a porous silver plate is electrochemically oxidized.

CONSTITUTION: When a porous silver plate is electrochemically oxidized in an aqueous KOH soln. by supplying an electric current, a silver peroxide plate is manufactured by reactions represented by equations I , II. Practically, the surfaces of silver granules are first converted into silver peroxide, and the internal silver of the granules is liable to remain as it is. In a conventional method, after supplying an electric current for a fixed time, discharge is carried out for a fixed time, charge is carried out again, and the operations are repeated. The quantity of electricity becomes 2W3 times the theoretical quantity. On the basis of the experimental fact that silver is not chemically converted by charge after attainment to the final level voltage, chemical conversion is carried out while measuring the voltage, and once the final level voltage is attained, discharge is carried out for a fixed time. Charge is carried out again, and the operations are repeated once or more. Ineffective charge is eliminated, charge time is shortened, and the waste of power is prevented.