Question

Write working of NICAD storage cell. Also write its applications.

Answer 1

Working of NICAD:

NICAD is a rechargeable secondary dry cell. It consists of a cadmium anode. The cathode is nickel(IV) oxide, NiO₂ supported on Ni. The electrolyte solution is basic (KOH).

The electrode reactions taking place are:

\[\ce{Cd_{(s)} + 2OH^-_{ (aq)} -> Cd(OH)_{2(s)} + 2e-}\]	(Oxidation at anode)
\[\ce{NiO_{2(s)} + 2H2O_{(l)} + 2e- -> Ni(OH)_{2(s)} + 2OH^-_{ (aq)}}\]	(Reduction at cathode)
Overall cell reaction: \[\ce{Cd_{(s)} + NiO_{2(s)} + 2H2O_{(l)} -> Cd(OH)_{2(s)} + Ni(OH)_{2(s)}}\]

The cell can be recharged as the reaction products are solids that adhere to the electrode surface. It produces a potential of about 1.4 V. The cell has longer life than other dry cells.

Applications of NICAD:

The NICAD cell is used in electronic watches, calculators, photographic equipment.