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