BATTERIES AND ITS TYPES
A battery is an arrangement of several electrochemical cells connected in series that can be used as a source of direct electric current. A cell is one that contains only one anode and cathode, but a battery contains several anodes and cathodes. TYPES OF BATTERIES: (a) Primary Battery or Primary Cells In the case of a primary battery, the electrode and the electrode reactions cannot be reversed by passing an external electrical energy. The reactions occur only once and after use, they become dead. Therefore, they are not rechargeable. Example: Dry cell, Mercury cell (b) Secondary Battery or Secondary Cells In case of a Secondary battery, the electrode reactions can be reversed by passing an external electrical energy. Therefore, they can be recharged by passing an electrical current and used again again. These are called storage cells or accumulators. Example: Lead-acid storage cell, nickel-cadmium cell