New amorphous thin-film lithium electrolyte and rechargeable microbattery

Sputtering of Li₃PO₄ in pure N₂ results in the formation of an amorphous lithium electrolyte that is suitable in contact with lithium and has electrical properties that are suitable for application in a thin-film cell. Thin-film rechargeable lithium cells have been fabricated and characterized using this electrolyte between a lithium anode and an amorphous vanadium oxide cathode. The open circuit voltage of the cell is 3.6 to 3.7 V, and it has a capacity of 130 μAh/cm² when discharged to 1.5 V. The AC impedance of the cells measured at different stages of discharge indicate a significant decrease in internal resistance at about the midpoint of the discharge