Which statement describes the role of the nickel-cadmium electrolyte during charging and discharging?

• A. The electrolyte does not enter into the chemical changes that occur during charging or discharging
• B. The electrolyte is the energy storage medium
• C. The electrolyte participates directly in producing electrical energy
• D. The electrolyte converts chemical energy to electrical energy only when heated

Answer: (A)

In a nickel-cadmium cell, the electrolyte (typically a potassium hydroxide solution) serves mainly as an ion-conducting medium. The chemical energy is stored in the electrode materials themselves, not in the electrolyte. During charging and discharging, hydroxide ions move through the electrolyte to balance charge as electrons flow through the external circuit and as the electrode materials undergo redox changes. The electrolyte participates by providing the ions needed for the electrode reactions, but it does not undergo a net chemical change that stores energy. That’s why the electrolyte isn’t the energy storage medium, doesn’t directly produce electrical energy, and doesn’t require heating to convert chemical energy to electrical energy.