The term ‘de-polariser’ has been used todenote a substance used in a primary cell toprevent a buid up of hydrogen gas bubbles. Abattery de-polariser takes up electrons duringdischarge of the cell, therefore it is always anoxidizing agent (Manganese dioxide) Manganesedioxide is used as de-polarizes in dry cell. 2NH4++2Mn2O2→Mn2O3+H2O+2NH3