磷酸铁锂在不同醇溶液中的溶剂热合成及其电化学性能

Solvothermal systhesis and electrochemical properties of LiFePO_4 using different solvents

分别以乙醇、乙二醇以及丙三醇/水为溶剂,采用溶剂热法合成橄榄石结构的磷酸亚铁锂(LiFePO4)。运用XRD,SEM和FTIR等手段,对产物晶体结构、颗粒形貌和表面微观结构进行表征,探讨溶剂热合成LiFePO4时不同溶剂对产物形貌和结构的影响,同时运用恒流充放电测试和循环伏安方法对所得产物的电化学性能进行研究。研究结果表明:以乙二醇为溶剂合成的LiFePO4呈均匀片状结构,具有粒度小、厚度薄的特点,这种结构缩短了锂离子的扩散距离,有利于电化学性能的提高,其0.1C倍率放电比容量达到161.7 mA.h/g,1C倍率放电时容量仍保持132.6 mA.h/g;在0.1C倍率下,50次循环后容量保持率为98.02%。

The olivine lithium ion phosphate（LiFePO4） was prepared via solvothermal reaction using ethanol,ethylene glycol（EG） and glycerol–water as solvents,respectively.The crystalline structure,particle morphology and surface microstructure of products were characterized by high-energy synchrotron X-ray diffraction（XRD）,scanning electron microscopy（SEM） and Fourier transform infrared（FTIR） spectroscopy,respectively.The effects of different solvents on the morphologies and structures were investigated,and the electrochemical properties of the products were investigated by charge/discharge test and cyclic voltammetry（CV）.The results show that LiFePO4 nanosheet obtained by using EG as solvent has small size and thin features,which reduces the lithium ion diffusion distance and favors the improvement of electrochemical performance,it can deliver an initial discharge capacities of 161.7 mA·h/g^-1 at 0.1C,132.6 mA·h/g^-1at 1C and the cycling capacity retention rate reaches 98.02% over 50 cycles at 0.1C.