Fabrication of thin-film batteries composed of LiCoO2, Li3PO4, and Li layers

Abstract This paper reports the fabrication of thin-film batteries which are composed of three stacking layers: LiCoO 2 , Li 3 PO 4 , and Li. First, a LiCoO 2 layer is constructed on an electron-conductive substrate by pulsed laser deposition as a cathode. The crystallinity of the LiCoO 2 layer is mainly controlled by the cationic ratio of Li and Co. Subsequently, an amorphous Li 3 PO 4 layer with a high ionic conductivity is further deposited on the cathode LiCoO 2 layer by radio frequency magnetron sputtering as a solid electrolyte. To avoid any possible damage which causes the formation of resistive species between LiCoO 2 and Li 3 PO 4 , bias control of the substrate during Li 3 PO 4 deposition is essential. Finally, a Li metal layer is deposited as an anode/current collector on the Li 3 PO 4 /LiCoO 2 bilayer by resistive heating evaporation in a vacuum at an elevated temperature for the formation of a low resistive interface. The fabricated three-layer thin-film battery shows a high-rate capability when the LiCoO 2 layer is a (104)-oriented epitaxial film.