Galvanic cells useful in day-to-day life

Voltaic (or galvanic) cells in common use can be classified as primary and secondary cells.

i. Primary voltaic cells : When a galvanic cell discharges during current generation, the chemicals are consumed. In a primary voltaic cell, once the chemicals are completely consumed, the cell reaction stops — the cell reaction cannot be reversed even after reversing the direction of current flow, and these cells cannot be recharged. The most familiar example is the dry cell.

ii. Secondary voltaic cells : In a secondary voltaic cell, the chemicals consumed during current generation can be regenerated. For this purpose an external potential slightly greater than the cell potential is applied across the electrodes; this results in reversal of the direction of current flow, causing the reversal of the cell reaction. This is recharging of the cell. The voltaic cells which can be recharged are called secondary voltaic cells. …