A　series　of　fluorine-doped　lithium　trivanadates　LiV3O8-yFz　(z　=　0,　0.03,　0.05,　0.1,　0.15,　0.2　and　0.5)　were　synthesized　by　the　solid-state　reaction.　X-ray　diffraction　(XRD),　Fourier　transform　infrared　(FTIR)　and　scanning　electron　microscope　(SEM)　tests　show　that　a　proper　amount　of　fluorine　substituting　for　oxygen　in　LiV3O8　can　modify　its　structure　and　surface　morphology.　Charge-discharge　tests　show　that　the　doped　samples　with　a　proper　amount　of　fluorine　display　good　cycling　stability,　high　coulombic　efficiency　and　good　rate　capability,　compared　with　undoped　sample.　The　cyclic　voltammetry　(CV),　area-specific　impedance　(ASI)　and　electrochemical　impedance　spectroscopy　(EIS)　tests　indicate　that　the　doped　samples　with　a　low　fluorine　content　can　stabilize　the　interface　between　the　surface　layer　of　the　active　particles　and　the　electrolyte　after　cycling,　while　a　high　fluorine　content　form　an　unstable　interface.　The　fluorine　substitution　is　a　convenient　and　effective　method　for　improving　the　electrochemical　performances　of　LiV3O8.　©　2008　Elsevier　Ltd.　All　rights　reserved.