We report on the effects of depositing a protective inorganic solid electrolyte LiAlF4 coating on amorphous V2O5 electrode in terms of long-term cycling efficiency and stability of the V2O5 in a liquid electrolyte. Two V2O5 thin-film electrodes were fabricated for extensive cyclic durability testing in a LiClO4/propylene carbonate liquid electrolyte: One V2O5 film had no overlying coating while the other had a protective thin film of solid lithium ion conducting LiAlF4. The protected V2O5 exhibited improved durability in terms of constant capacity with repeated cycling up to 800 cycles, while the uncoated V2O5 electrode displayed significant capacity loss. Our results demonstrate that deposition of an inorganic solid electrolyte (LiAlF4) on amorphous V2O5 films serves as a protective overlayer and enhances the long-term cycling efficiency and stability of the V2O5 in a liquid electrolyte. (C) 2003 The Electrochemical Society.