Electrochemical properties of sputter-deposited MoO3 films in lithium microbatteries

Molybdenum oxide (MoO3) films were prepared by magnetron sputtering using an Mo target. The films were sputtered in the reactive atmosphere of an argon–oxygen gas mixture under various substrate temperatures, Ts, and oxygen partial pressures, p(O2). The effects of the growth conditions on the microstructure were examined using reflection high-energy electron diffraction and x-ray photoelectron spectroscopy. The analyses indicate that stoichiometric and polycrystalline MoO3 films were obtained at Ts = 445 °C and p(O2) = 61%. The applicability of the sputtered MoO3 films for lithium microbattery application has been demonstrated. The discharge–charge profiles, the kinetics of lithium intercalation process in the film, and the cycling behavior have been investigated in detail to understand the effect of microstructure on the electrochemical performance.