Fabrication of all-solid-state battery using epitaxial LiCoO2 thin films

• Fabrication of all-solid-state thin film lithium ion secondary battery using epitaxial LiCoO2 thin film.
• Control of crystal orientation of epitaxial LiCoO2 thin film.
• Observation of Li ion insertion/extraction reactions in the thin film battery by cyclic voltammetry measurement.

We demonstrate the orientation control of LiCoO2 epitaxial thin films deposited on (110)-2 × 1 reconstructed surfaces of Au and Pt by using pulsed laser deposition. The epitaxial LiCoO2 thin films have CoO2 layers tilted with respect to the surface normal, which is suitable for Li-ion insertion/extraction reactions in LiCoO2. We show the successful operation of all-solid-state thin-film Li-ion batteries by employing the epitaxial LiCoO2 thin films as cathodes. The electrochemical properties of epitaxial films in all-solid-state batteries are improved compared to the batteries using liquid electrolyte.