What is a nickel–cadmium storage cell?

A nickel–cadmium (Ni-Cd) cell is a rechargeable battery that uses nickel oxide hydroxide as the positive electrode and cadmium as the negative electrode in an alkaline electrolyte.

Ni-Cd batteries are secondary cells, meaning they can be recharged many times. They use a potassium hydroxide (KOH) solution as the electrolyte. During discharge, cadmium at the negative electrode forms cadmium hydroxide, and nickel oxyhydroxide at the positive electrode converts to nickel hydroxide.

Recharging reverses these reactions. Ni-Cd cells deliver stable voltage, handle high discharge currents, and perform well at low temperatures. They are used in emergency lighting, power tools, and aviation. However, cadmium is toxic, so disposal must follow e-waste rules. They also can suffer from “memory effect” if repeatedly partially cycled, though smart charging reduces this issue.

Key properties

• Nominal cell voltage: about 1.2 V
• Good cycle life, robust, fast charge capable
• Works in wide temperature range
• Environmental concern: cadmium toxicity
• Applications: power tools, backup systems, aviation electronics