Past developments and the future of nickel electrode cell technology

The nickel hydroxide electrode has evolved over nearly 100 years from the pocket electrode structure through to the present design of a light weight, porous, plaque structure. Before discussing the historical aspects, it would be helpful to point out that there are basically two parts to the electrode: the active material and the current (electron) collector. Together they provide the essential properties for storing and converting the chemical energy into electrical energy and vice versa. The electrical energy is stored in the nickel hydroxide active material during charge, in which the electrode is oxidized. The chemical energy is converted back to electrical energy during discharge. The active material is itself initially non-conductive. Therefore it must be housed in a high conductivity metallic structure which serves as the current collector. This is, in turn, connected to another high conductivity metallic structure called the terminal.