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Thin film amorphous electrolytes with compositions xLi2O:ySiO2:zP2O5 were deposited by single and dual source rf magnetron sputtering and their compositions determined by electron and ion beam techniques. Films containing P but no Si were composed of mainly orthophosphate and some linear chain phosphate anions, whereas single phase films containing Si and P were evidently composed of branched and possibly cyclic and extended network structures. Films with Si/P > 1 appeared to contain two or more amorphous phases. In the range of compositions investigated, the lithium ion conductivity depends mainly on the lithium ion mobility which is sensitive to the structure of the films. An open circuit voltage from 1 to 3 V measured between blocking metal contacts on the electrolyte thin films suggests that the films mightbe electrets.

A rechargeable thin-film lithium battery that can be used as a miniature power supply for small devices has been recently developed. The battery consists of an amorphous vanadium pentoxide (aV2O5) cathode, an amorphous lithium phosphorus oxynitride (Lipon) electrolyte, and a lithium anode. A thin-film cover layer protects the battery from exposure to air and water vapor. The battery can deliver u p to 60 p A l c m 2 of current between 3.6 V and 1.5 V. Higher voltages can be achieved by fabricating two or more cells in series. A l-cm2 cell with a 1 to 1.5-pmthick cathode discharged from 3.6 to 1.5 V at 12 pA typically yields about 440 mC and delivers about 1 J. Using the combined mass of the cathode, electrolyte, and the anode (3x over capacity), the specific energy of the cell is 1.4 x 106 J/kg and the energy density is 2.1 x 106 J/1.