ZINC MANGANESE-DIOXIDE GALVANIC CELL USING ZINC-SULFATE AS ELECTROLYTE - RECHARGEABILITY OF THE CELL

The discharge capacity of the Zn vertical ZnSO//4(aq) vertical MnO//2 galvanic cell increases with increase in the concentration of ZnSO//4; use of a 2 M aqueous solution of ZnSO//4 gives 65 percent utilization of MnO//2. When the cell is charged after discharging, X-ray diffraction analysis of the positive electrode material indicates regeneration of gamma -MnO//2 during the charging. Repeated charging and discharging under various modes reveals that the cell is rechargeable more than 30 times. When the cell is charged to 1. 7 v and discharged to 0. 9 v, the cell shows about 100 percent coulombic efficiency with an average discharging voltage of about 1. 3 v (energy efficiency equals 83 percent) and 57 percent utilization of MnO//2. The cell is rechargeable after discharging to 0 v.