Interfaces between LiCoO2 and sulfide solid electrolytes were modified in order to enhance the high-rate capability of solid-state lithium batteries. Thin films of oxide solid electrolytes, Li4Ti5O12, LiNbO3, and LiTaO3, were interposed at the interfaces as buffer layers. Changes in the high-rate performance upon heat treatment revealed that the buffer layer should be formed at low temperature to avoid thermal diffusion of the elements. Buffer layers of LiNbO3 and LiTaO3 can be formed at low temperature for the interfacial modification, because they show high ionic conduction in their amorphous states, and so are more effective than Li4Ti5O12 for high-power densities. (c) 2008 Elsevier BY All rights reserved.