Characterization of Stable Solid Electrolyte Lithium Silicate for Thin Film Lithium Battery

Lithium silicate thin films were successfully deposited by pulsed laser deposition (PLD) technique using an ArF excimer laser. The ionic conductivities, the structures and the stability against CO2 of the lithium silicate films were examined. The ionic conductivity value at 25 degrees C was 2.5x10(-8) Scm(-1) for Li2SiO3 film and 4.1x10(-7) Scm(-1) for Li4SiO4 film. Li4SiO4 film was found unstable to CO2 to form Li2CO3, but Li2SiO3 film was stable. Solid-state thin film batteries (TFB) consisting of an amorphous lithium silicate electrolyte, crystalline LiCoO2 positive electrode and Li metal negative electrode were fabricated and characterized. The batteries performed good stabilities for cycles. Higher apparent capacity was obtained in the TFB using Li4SiO4 electrolyte than Li2SiO3, which is due to the higher conductivity of the Li4SiO4 film.