A process for preparing a lithium-rich antiperovskite electrolyte film involves forming a composite target of precursor metal oxide(s) and metal halide(s), and exposing the target to a pulsed laser beam under conditions suitable for depositing a film of lithium-rich antiperovskite on a surface. In some embodiments the process is used to prepare a film of Li.sub.3OCl from a target largely composed of Li.sub.2O and LiCl. Exposure of the target to a pulsed laser beam deposits antiperovskite electrolyte Li.sub.3OCl on a substrate. In another embodiment, sputtering may be used to prepare films of lithium-rich antiperovskites using the composite target of precursor metal oxide(s) and metal halide(s).
ACKNOWLEDGMENT OF GOVERNMENT SUPPORT
 This invention was made with government support under Contract No. DE-AC52-06NA25396 awarded by the U.S. Department of Energy. The government has certain rights in the invention.