L i F e 1-yMg yP O4的制备及电化学性能研究

采用机械活化一步固相法, 在F e位掺杂 Mg 2+ 合成了结晶度较好的 L i F e 1-yMg yP O4。采用 XR D、S EM 等方法对L i F e 1-yMg yP O4的结构和形貌进行了表征, 利用恒电流充放电法研究了 Mg 2+ 掺杂对 L i F e 1-yMg yP O4电化学性能的影响。结果表明, 适量 Mg 2+掺杂不改变L i F e P O4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L i F e P O4的倍率性能和循环稳定性。L i F e 0. 9 9Mg 0. 0 1P O4在0. 1C和1C倍率条件下首次放电比容量分别为1 5 8. 7mA h / g和1 4 1. 9mA h / g, 循环5 0次后放电比容量几乎没有衰减。

Synthesis and Electrochemical Properties of LiFe1 - y Mgy PO4

Fe site dopedL i F e 1-yMg yP O4 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 LiFePO4. Accordingly, the rate performance and the cycling stability of LiFePO4 can be improved effectively. The initial discharge capacity of LiFe0.99Mg0.01PO4 was 158.7 mAh/g at 0.1 C rate and 141.9 mAh/g at 1.0 C rate. And the capacity has almost no attenuation after 50 cycles.