Mg^(2+)掺杂对LiFePO_4/C结构和性能的影响

Influence of Mg^(2+) doping on the structure and performance of LiFePO_4/C cathode material

以乙酸镁为镁源,用LiOH.H2O、Fe(NO3)3.9H2O、NH4H2PO4为原料,通过水溶液法制备了掺杂Mg2+的LiFePO4/C正极材料。用XRD、SEM、恒流充放电测试、循环伏安(CV)和交流阻抗谱(EIS)方法,研究了Mg2+掺杂对LiFePO4/C的结构、形貌及电化学性能的影响。研究结果表明:Mg2+掺杂没有改变LiFePO4橄榄石型的结构;在0.1 C(1 C=170 mAh/g)的充放电倍率下,Mg2+掺杂使正极材料首次放电比容量从153 mAh/g提高到159 mAh/g,经20循环次后,容量几乎无损失;电化学交流阻抗表明,掺杂后材料阻抗Rct从463.1Ω减小到322.8Ω。

Mg2＋ doped LiFePO4/C cathode material was synthesized with LiOH·H2O,Fe（NO3）3 ·9H2O,and NH4H2PO4 by an aqueous solution method with magnesium acetate as magnesium source.Influence of Mg2＋ doping on the structure,morphology and electrochemical properties of LiFePO4/C cathode material were tested by X-ray diffraction（XRD）,scanning electronmicroscopy（SEM）,cyclic voltammetry（CV）,EIS and galvanostatic charge-discharge tests.The results showed that Mg2＋ doping didn＇t change olivine structure of LiFePO4.At 0.1 C（1 C =170 mAh/g） rate,a initial discharge capacity of Mg2＋ doped material was 159 mAh/g,but that of undoped material was 153 mAh/g.After 20 cycles,the capacity of Mg2＋ doped material almostly did not fade.And the impedance Rct of the Mg2＋ doped material was 322.8 Ω,while that of the undoped material was 463.1 Ω.