The electrolyte of a nickel-cadmium battery is highest when the battery is fully charged.

The electrolyte of a nickel-cadmium battery is highest when the battery is fully charged.

• A. Fully charged
• B. Discharged
• C. Resting
• D. Overcharged

Answer: (A)

In nickel-cadmium cells, the electrolyte is a potassium hydroxide solution, and its concentration in the liquid phase changes with how charged the battery is. As charging progresses, the electrode reactions drive more hydroxide ions into the solution, so the electrolyte becomes more concentrated and its density rises. That means the electrolyte is at its highest concentration when the cell is fully charged. When the battery is discharged, ions are drawn into solid compounds at the electrodes, decreasing the amount of free OH− in solution and lowering the electrolyte concentration. Resting allows some leveling out but doesn’t reach the peak seen at full charge. Overcharging mainly causes gas formation rather than further increasing electrolyte concentration.

In nickel-cadmium cells, the electrolyte is a potassium hydroxide solution, and its concentration in the liquid phase changes with how charged the battery is. As charging progresses, the electrode reactions drive more hydroxide ions into the solution, so the electrolyte becomes more concentrated and its density rises. That means the electrolyte is at its highest concentration when the cell is fully charged. When the battery is discharged, ions are drawn into solid compounds at the electrodes, decreasing the amount of free OH− in solution and lowering the electrolyte concentration. Resting allows some leveling out but doesn’t reach the peak seen at full charge. Overcharging mainly causes gas formation rather than further increasing electrolyte concentration.