2022 Volume 2022 Article ID: 220202
In order to induce various electronic phase transitions in strongly correlated electron systems, lithium-ion battery-like electrochemical cells based on highly crystalline epitaxial thin films of transition-metal oxides have been developed. The electronic states of band insulators, Mott insulators, heavy-fermion metals, and superconductors are studied in detail from their transport, optical, and structural properties. This method has become a powerful tool for precise electrochemical doping of single samples and in-situ measurement of modulated electronic states. In this review, we present the results obtained in our previous studies, clarify the effectiveness and scope of application of this method, and look forward to its possible application to electrochemical devices.