Molecular layer deposition of Li-ion conducting “Lithicone” solid electrolytes

Abstract

We demonstrate the fabrication of Li-containing (“lithicone”) thin films prepared via molecular layer deposition (MLD) using lithium tert-butoxide and ethylene glycol. X-ray photoelectron spectroscopy reveals that the stoichiometry of the lithicone is Li_1.5C₂O_1.8 (H omitted), with C–O–Li moieties present in the film. The bonding environment of lithicone is distinct from that of lithium carbonate or MLD alucone films. Electrochemical impedance spectroscopy measurements show that annealed lithicone films exhibit room temperature ionic conductivity of 3.6–5 × 10⁻⁸ S cm⁻¹ with an activation energy of ∼0.6 eV. The lithicone MLD process provides a pathway to further develop hybrid inorganic–organic Li-ion conducting materials for future battery applications.