Understanding a Dead Battery

• As the Zn Cu2+ voltaic cell is used, the zinc electrode dissolves away as zinc is oxidized to zinc ions. Similarly, the solution is depleted of Cu2+ ions as they deposit as solid Cu.
• Once the zinc electrode is dissolved and the Cu2+ ions are depleted, the cell is dead.
• Some voltaic cells, such as those employed in rechargeable batteries, can be recharged by running electrical current—from an external source—in the opposite direction. This causes the regeneration of the reactants, allowing repeated use of the battery.