热电池用锂钒氧化物正极材料的放电模式  

Discharge mechanisms of vanadium-lithium oxide cathodes for thermal cell

作　　者：李志友[1] 曹笃盟[1] 周科朝[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,长沙410083

出　　处：《中国有色金属学报》2008年第1期59-66,共8页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(50002015)

摘　　要：合成V2O5-V2O3-Li2O体系的3种化合物LiV3O8、γ-LiV2O5和VO2,并以其作为热电池正极活性物质、锂硼合金为负极、LiCl-KCl为电解质进行500℃、100 mA/cm2的放电实验,研究该正极活性物质在放电中的物相转变过程,同时对V2O5、β-Li0.3V2O5、VnO2n+1和VnO2n?1的放电反应进行分析。结果表明,LiV3O8、γ-LiV2O5和VO2均进行分解式放电反应,生成LiV2O5、Li3VO4、V2O3和LiVO2等物相。分析认为V2O5和β-Li0.3V2O5可能出现嵌入反应直至转变为γ-LiV2O5,再由γ-LiV2O5进行放电,VnO2n+1和VnO2n?1放电最终也将生成Li3VO4和V2O3。γ-LiV2O5和VO2放电过程中V4+歧化反应产生Li3VO4相和V2O3相,Li3VO4相较差的电子导电性使正极材料失去快速放电能力。Thermal battery potential cathode materials, LiV3O8, y-LiV2O5 and VO2, were synthesized and discharged at a current density of 100 mA/cm^2, 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, p-Li0.3V2O5, VnO2n＋l 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-V203-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 V^4＋ 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.

关 键 词：钒氧化物 锂钒氧化物 正极 热电池 

分 类 号：TM911.1[电气工程—电力电子与电力传动]