Types of Batteries
A battery is an electrochemical cell, or a series of combined electrochemical cells, that can be used as a source of direct electric current at a constant voltage. There are generally two types of batteries:
- primary batteries and
- secondary batteries.
Dry cell battery
The anode of a cell consists of a zinc can or container that is in contact with manganese dioxide (MnO2) and an electrolyte. The electrolyte consists of NH4Cl and ZnCl2 in water.
Lead storage battery
It is a reversible cell, which acts as electrochemical cell when discharged and functions as electrolytic cell during charging process. The reactions occurring at anode and cathode get reversed during charging and discharging process. Each cell of a lead storage battery has a lead anode and a cathode made of lead dioxide powder packed in a metal plate (lead grid). The anode is also a lead grid with interstices filled with spongy lead. Both the cathode and the anode are immersed in an aqueous solution of sulphuric acid (35% by weight), which acts as an electrolyte.
During the discharging of lead storage battery, at anode, Pb is oxidized to Pb2+ and an insoluble white precipitate of PbSO4 is formed which remains within the lead grid. At cathode, Pb4+ (from PbO2) is reduced to Pb2+ and PbSO4 again precipitates out.
Under normal operating conditions, each cell produces a potential of 2 V.