镁、锆离子掺杂磷酸铁锂的制备及其电化学性能

Preparation and Electrochemical Performances of Magnesium or Zircon Doped Lithium Iron Phosphates

采用燃烧法,在不通入惰性气体保护的环境下,合成了Mg^(2+)、Zr^(4+)掺杂的磷酸铁锂(LiFePO_4)正极材料.通过X射线衍射、傅立叶变换红外光谱、扫描电子显微镜、恒电流充放电循环技术,对材料的结构和电化学性能(放电性能、循环性能)进行表征.结果表明,Mg^(2+)、Zr^(4+)的掺入没有改变材料的橄榄石型结构,但显著改善了材料的电化学性能,其中Zr^(4+)掺杂的LiFePO_4具有更高的放电比容量,在0.2 C放电倍率下最高达到143.4 m Ah/g,且循环性能良好(经50次循环后放电比容量为126.3 m Ah/g).

Mg^2＋or Zr^4＋ doped lithium iron phosphates （LiFePO4） were synthesized via combustion method without inert gas, then they were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy, and their electrochemical performances including discharge performance and cycle performance were measured by galvanostatic charge-discharge cycling technique. The results indicated that Mg^2＋or Zr^4＋doped LiFePO4 still kept the structure of olivine but their electrochemical performances were greatly improved compared with the undoped LiFePO4. In addition, Zr^4＋ doped LiFePO4 exhibited the best discharge specific capacity of 143.4 mAh/g at 0.2 C discharge rate and the discharge specific capacity of it remained 126.3 mAh/g after 50 charge/discharge cycles, showing good cycle performance.