Amorphous thin film electrolytes in the system Li4SiO4-Li3PO4 were prepared by pulsed laser deposition (PLD). The ionic conductivity of the amorphous film at the composition 50Li(4)SiO(4)center dot 50Li(3)PO(4) (mol%) was 1.6 x 10(-6) S cm(-1) at room temperature which is higher than the conductivities of Li3PO4 and Li4SiO4 films. The 50Li(4)SiO(4)center dot 50Li(3)PO(4) film was coated on LiCoO2 active material particles by PLD. All-solid-state lithium secondary batteries using the coated LiCoO2 electrode and the Li2S-P2S5 solid electrolyte were fabricated. The PLO coating of oxide film with high conductivity on LiCoO2 was effective in decreasing the electrode/electrolyte interfacial resistance and developing power density of the all-solid-state cells. (C) 2010 Elsevier B.V. All rights reserved.