铝/氟比对改性尖晶石锰酸锂性能的影响

Influence of the n(Al)∶n(F) Ratio on Performance of Modified LiMn_2O_4 Materials

采用草酸铝、氟化锂与尖晶石LiMn_2O_4进行高温固相反应,制备出改性尖晶石LiMn_2O_4材料。对材料进行了XRD、SEM分析及电性能测试,结果表明,改性材料均基本保持了尖晶石主体结构,晶格常数随n(Al)∶n(F)比例的增大而减小;Al^(3+)、F^-的引入可以引起材料颗粒表面形貌的变化,产生规则结晶,而颗粒表面结晶的大小受n(Al)∶n(F)比值的影响;改性材料的高温循环性能得到明显改善,改性前的LiMn_2O_450℃10周循环容量衰减率为24.4%,改性材料50℃10周循环容量衰减率可降低到2.6%。

LiMn2O4 materials modified by aluminum oxlate and lithium fluoride were synthesized by high-temperature solid-state reaction. The morphology, structure and electrochemical properties were investigated by XRD, SEM and electrochemical tests. The XRD results indicate that all the modified materials possess spinel LiMn204 structure, and the lattice parameters reduce with n （Al） ：n （F） increasing. The morphologies of modified materials are influenced by Al^3＋ and F^-. The capacity loss after ten cycles for pure LiMn2O4 is 24.4%, whereas that for the materials modified by aluminum oxlate and LiF is 2.6%.