Fabrication of EQCM-compatible LiCoO2 thin-film electrodes via electrostatic spray deposition: Toward in situ leaching studies

Layered LiCoO 2 thin films applicable to the electrochemical quartz crystal microbalance (EQCM) were fabricated using electrostatic spray deposition (ESD). Optimized deposition parameters produced uniform, dense films, and annealing at 550 °C yielded a well-defined layered structure confirmed by Raman spectroscopy. In EQCM measurements, the films used as electrodes exhibited stable frequency responses, and the mass changes derived from frequency shifts agreed with values calculated from charge transfer. This study reports the first successful integration of layered LiCoO 2 thin films into an EQCM system through a simple low-temperature process and establishes its suitability for in situ monitoring of electrochemical reactions. • Layered LiCoO 2 electrodes operable in an EQCM system were successfully fabricated. • LiCoO 2 thin films were deposited via electrostatic spray deposition (ESD). • Optimized ESD conditions produced stable layered structures, confirmed by surface and electrochemical analyses. • In-situ applicability in EQCM was demonstrated, enabling leaching studies using the system.