Alkaline cell is also manganese zinc cell type; it is shown in figure (a). It is available either as a primary or secondary cell but the primary type is more common. Output of alkaline cell is 1.5 V as carbon zinc cell but the alkaline cell lasts much longer.
The electrochemical system consists of a powdered zinc anode and a manganese dioxide cathode in an alkaline electrolyte. The electrolyte is potassium hydroxide, which is the main difference between the alkaline and Laclanche cells. Hydroxide compound are alkaline with negative hydroxyl (OH) ions, while an acid electrolyte has positive hydrogen (H) ions. Voltage output from the alkaline cell is 1.5 V.
The alkaline cell has many applications because of the ability to work with high efficiency with continuous high discharge rates. Depending on the application, an alkaline cell can provide up to seven times the service of a Leclanche cell. As examples, in a transistor radio an alkaline cell will normally have twice the service life of a general purpose carbon zinc cell in toys the alkaline cell typically provides seven times more service.
The outstanding performance of the alkaline cell is due to its low internal resistance. Its ri is low because of the dense cathode material, the large surface area of the anode in contact with the electrolyte, and the high conductivity of the electrolyte. In addition, alkaline cells will perform satisfactorily at low temperatures