Nickel cadmium cell (NiCd)
The active components of a rechargeable NiCd battery in the charged state consist of nickel hydroxide (NiOOH) in the positive electrode and cadmium (Cd) in the negative electrode. For the electrolyte, usually caustic potash solution (potassium hydroxide) is used. Due to their low internal resistance and the very good current conducting properties , Ni-Cd cells can supply extremely high currents and can be recharged rapidly.
These cells are operating in a large temperature range, from +60°C down to -20°C. The selection of the separator (nylon or polypropylene) and the electrolyte (KOH, LiOH, NaOH) is also of great importance. These constituents influence the voltage conditions in the case of a high current discharge, the service life and the overcharging capability of the cell. In the case of misuse, a very high-pressure may arise quickly.
For this reason these cells are equipped with a reversible safety valve, which can act several times. NiCd cells offer a long service life (depending on the type of application and charging unit up to 2000 cycles) thereby ensuring a high degree of the economy.