LiFe_(1-y)Mg_yPO_4的制备及电化学性能研究

Synthesis and Electrochemical Properties of LiFe_(1-y)Mg_yPO_4

采用机械活化一步固相法,在Fe位掺杂Mg2+合成了结晶度较好的LiFe1-yMgyPO4。采用XRD、SEM等方法对LiFe1-yMgyPO4的结构和形貌进行了表征,利用恒电流充放电法研究了Mg2+掺杂对LiFe1-yMgy PO4电化学性能的影响。结果表明,适量Mg2+掺杂不改变LiFePO4的晶体结构,同时可以细化颗粒粒径,增强导电性和可逆性,有效地提高LiFePO4的倍率性能和循环稳定性。LiFe0.99Mg0.01PO4在0.1C和1C倍率条件下首次放电比容量分别为158.7mAh/g和141.9mAh/g,循环50次后放电比容量几乎没有衰减。

Fe-site doped LiFe1-yMgy PO4 was synthesized by mechanical activation-one-step solidification method.The structure,morphology and electrochemical properties of the product were investigated by XRD,SEM,CV and galvanostatic charge/discharge determination.The effect of Mg2＋doping on electrochemical properties of the samples was discussed.The results show that the crystal structure of LiFePO4 was not changed after proper doping of Mg2＋.In the meantime,the proper doping can refine the particle size,and improve the electrical conductivity and reversibility of LiFePO4.Accordingly,the rate performance and the cycling stability of LiFePO4 can be improved effectively.The initial discharge capacity of LiFe0.99Mg0.01PO4 was 158.7mAh/g at 0.1Crate and 141.9mAh/g at 1.0Crate.And the capacity has almost no attenuation after 50 cycles.