Nickel-cadmium battery

A nickel-cadmium (NiCd) battery uses nickel hydroxide for the positive electrode, cadmium for the negative electrode and potassium hydroxide solution as the electrolyte. Stationary NiCd batteries are built either as vented pocket-plate or sintered-plate types, with vents for electrolyte maintenance, or as sealed fiber-plate types with a pressure relief valve. Compared with lead-acid batteries, they need a much higher charging voltage, are less efficient and cost much more. They are robust, tolerate cycling and work well in the cold, so they are used in certain special applications. Vented NiCd batteries can release hydrogen, so the battery area needs proper ventilation. The caustic electrolyte calls for proper PPE and spill control when you handle it, and cadmium is toxic and a hazardous waste.