Linking battery electrode science with correlated and quantum materials

Every time a battery is cycled between charged and discharged states, ions and electrons are shuttled between electrodes. In this process, beyond storing charge, the addition and removal of ions in electrodes provides a reversible and tunable handle over the electronic structure and magnetic order. This Research Update paper connects the chemistry of battery electrode materials with the physics of emergent phenomena, including insulator--metal transitions, geometric magnetic frustration, charge and vacancy ordering, and cooperative Jahn--Teller effects. Ion insertion is suggested as being a potentially overlooked handle for the design of functional materials, and open experimental and theoretical challenges are highlighted.