Charge can be carried through a material in different ways. We are most familiar with the charge that is carried by the electrons that help make up atoms. But there are many important devices that depend on the motion of charged atoms (ions) themselves, rather than just their constituent electrons. Examples include lithium batteries, which depend on the movement of lithium ions during battery charge and discharge. Similarly, fuel cells depend on the movement of hydrogen and oxygen ions in the process of generating electricity. The research thrust of solid-state ionics involves basic and applied research on the movement of ions through materials.
