The positive electrode material of nickel cadmium batteries is a mixture of nickel and graphite powder, while the negative electrode material consists of sponge mesh like cadmium powder and cadmium oxide powder. The electrolyte is usually hydrogen. When the ambient temperature is high, use a sodium chloride solution with a density of 1.17-1.19 (at 15 ℃). When the ambient temperature is low, use a potassium solution with a density of 1.19-1.21 (at 15 ℃). When the temperature is below -15 ℃, use a potassium solution with a density of 1.25~1.27 (at 15 ℃). To balance low-temperature performance and charge retention capability, sealed nickel cadmium batteries use potassium solution with a density of 1.40 (at 15 ℃). In order to increase the capacity and cycle life of the battery, a small amount of lithium hydroxide is usually added to the electrolyte (approximately 15-20 g per liter of electrolyte).
After charging a nickel cadmium battery, the active material on the positive electrode plate becomes nickel [NiOOH], and the active material on the negative electrode plate becomes metallic cadmium; After discharging a nickel cadmium battery, the active material on the positive electrode plate becomes nickel oxide, and the active material on the negative electrode plate becomes cadmium oxide.
