铌源和掺杂位置对LiFePO_4/C电化学性能的影响(英文)

Effect of Nb Source and Doping Site on Electrochemical Performance of LiFePO_4/C

使用Nb2O5和Nb(OC6H5)5为铌源对LiFePO4/C中的锂位和铁位分别掺杂,采用碳热还原法合成掺杂Nb的磷酸铁锂系列材料。运用X射线衍射仪、扫描电镜、循环伏安、交流阻抗谱和恒电流充放电测试等对材料进行表征。结果表明:相比掺杂位置,铌源对材料的颗粒形貌和粒径分布影响更大,而颗粒大小对材料的电化学性能,尤其是大倍率性能的提高有重要作用;掺杂在Li位的Nb元素比在Fe位能更好的稳定晶体结构,从而有利于提高循环性能。

Nb-doped LiFePOJC materials with different Nb sources and doping sites were synthesized by carbon thermal reduction method using Nb205 and Nb（OC6Hs）5 as Nb source. The materials were characterized by XRD, SEM, cyclic vohammetry （CV）, electrochemical impedance spectroscopy （EIS） and galvanostatic charge-discharge test. The results indicate that Nb source has stronger effect on the particle morphology and size distribution than that of doping site, and the particle size has significant importance on electrochemical performance, especially under high discharge rate. Doping Nb in Li site can stabilize the crystal structure better than doping in Fe site, to improve cycling performance.