钛离子掺杂对LiFe_(0.6)Mn_(0.4)PO_4/C电化学性能的影响

Effect of Doping with Ti4+ Ion on the Electrochemical Performance of LiFe_(0.6)Mn_(0.4)PO_4/C

采用固相法合成了钛离子掺杂LiFe0.6Mn0.4PO4/C正极材料.通过X射线衍射(XRD)、扫描电镜(SEM)以及电化学测试,对合成材料的结构、形貌和电化学性能进行了表征.结果表明:钛离子掺杂未影响材料的晶型结构,但显著改善了材料的电化学性能;Li(Fe0.6Mn0.4)0.96Ti0.02PO4/C材料表现出优异的倍率性能,0.1C倍率下其比容量为160.3mAh.g-1;在10C倍率下,比容量为134.7mAh.g-1;特别是在20C高倍率下仍然具有124.4mAh.g-1的放电比容量.电化学交流阻抗谱(EIS)和循环伏安(CV)测试结果说明,通过钛离子掺杂导致材料阻抗和极化的减少是材料倍率性能改善的主要原因.

Ti-doped LiFe0.6Mn0.4PO4/C materials were synthesized by a solid-state method. The structures, morphologies, and electrochemical performance of the materials were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and galvanostatic charge-discharge experiments. The results indicate that Ti4＋ doping does not change the structure of the materials, but remarkably improves their electrochemical performance.Li（Fe0.6Mn0.4）0.96Ti0.02PO4/C shows excellent rate performance, with initial specific discharge capacities of 160.3 and 134.7 mAh. g-1 at 0.1C and 10C rates. Even at the higher rate of 20C, it shows a discharge capacity of 124.4 mAh. g-1. Electrochemical impedance spectroscopy （EIS） and cyclic voltammetry （CV） analyses show that the resistance and the polarization of the LiFe0.6Mn0.4PO4/C composite electrode could be effectively decreased by Ti4＋ doping, which would account for the improved electrode performance.