Effects of sputtering pressure on the characteristics of lithium ion conductive lithium phosphorous oxynitride thin film

Lithium phosphorous oxynitride(Lipon) thin films as a lithium ion conductive electrolyte were prepared by radio frequency reactive sputtering in N-2 plasma. The properties of the amorphous Lipon solid electrolyte were investigated as a function of N-2 pressure during reactive sputtering. The ionic conductivity and the electrochemical stability of Lipon thin films improved drastically as the N-2 pressure decreased. The ionic conductivity closed to 10(-6) S cm(-1)supercript stop and obtained a stability window of 1.0-5.0 V with an N-2 pressure of 5 mTorr, where the number of nitrogen bonds between the phosphate groups were more than those formed at higher pressure. It was possible to fabricate the Li//LiCoO2 complete thin film battery using this Lipon solid electrolyte, which exhibited excellent discharge characteristics close to the theoretical capacity (ca. 69 uAhcm(-2) -um(-1)) and showed a considerably high rate capability.