CATHODE MATERIAL AND SECONDARY BATTERY USING THE SAME

摘要

A cathode material made of anhydrous ferric sulfate with a hexagonal crystal structure is presented for use in a secondary battery which generates a stable open-circuit-voltage of about 3.6 volts and offers a recharge cycling capacity of over 100 times. The cathode material is obtained by heating hydrous iron sulfate material in a temperature range between 250 and 600 .degree.C to remove the water of crystallization. The secondary battery made with this cathode material provides a long-service life and a stable output voltage economically, because the starting material, iron sulfate, is abundantly available at relatively low cost.