Abstract:Thermal battery potential cathode materials, LiV3O8, γ-LiV2O5 and VO2, were synthesized and discharged at a current density of 100 mA/cm2, with an anode of Li-B alloy and electrolyte of LiCl-KCl eutectic molten salt at 500 ℃. The attention was paid to the phase evolutions to investigate the discharge characteristics of these cathode compounds in the V2O5-V2O3-Li2O system at high temperature. The discharge reactions of V2O5, β-Li0.3V2O5, VnO2n+1 and VnO2n−1 were also discussed. The results indicate that LiV3O8, γ-LiV2O5 and VO2 all show decomposing discharge mechanism in which LiV2O5, Li3VO4, V2O3 and LiVO2 gradually appear. The phase relationship is schemed for the V2O5-V2O3-Li2O system to be discharged as thermal battery cathode, during which V2O5 and β-Li0.3V2O5 may firstly turn to dischargeable γ-LiV2O5 through the lithium-insertion reaction, VnO2n+1 and VnO2n−1 are both discharged to become the mixture of Li3VO4 and V2O3 finally. Because of the disproportionate reaction of V4+ in γ-LiV2O5 and VO2 on discharging, Li3VO4 and V2O3 are obtained. The low electron-conductivity of Li3VO4 may make these cathode materials all lose the discharge ability at high current density needed for thermal battery.

Key words: vanadium oxide; lithium vanadium oxide; cathode; thermal battery