A zinc-nickel battery works by converting chemical energy into electrical energy through a series of electrochemical reactions that take place in the battery's electrodes and electrolyte. During discharge, zinc atoms in the negative electrode (anode) oxidize to form zinc ions and electrons, which flow through an external circuit to power a device. At the same time, nickel ions in the positive electrode (cathode) react with the electrons to form nickel hydroxide. During charging, the process is reversed and the nickel hydroxide is converted back into nickel ions.