摘要
为了提高LiFePO4的倍率性能,用碳热还原法制备了Na+掺杂的LiFePO4/C复合正极材料,并用X射线衍射(XRD)、扫描电子显微镜(SEM)、红外光谱(FT-IR)、恒电流充放电技术、循环伏安(CV)和交流阻抗(EIS)研究了Na+掺杂对LiFePO4/C材料的结构、微观形貌和电化学性能的影响.结果表明,Na+掺杂的LiFePO4/C复合材料具有单一的橄榄石型晶体结构,不存在杂质衍射峰,Na+在Li位掺杂可提高材料的导电性能和Li+扩散速率,降低电极极化,能有效改善材料的循环性能和倍率性能.与LiFePO4/C相比,Li0.99Na0.01FePO4/C的0.5C、2C和5C放电比容量分别为147.6、126.4和105.1 mAh/g,并表现出良好的循环性能和倍率性能.
In order to improve the rate performance of lithium iron phosphate,Na＋ doped LiFePO4/C cathode ma-terials were prepared by carbothermal reduction technology.Samples were characterized by X-ray diffraction（XRD）,scanning electron microscope（SEM）,Fourier transfer infrared spectroscopy（FT-IR）,cyclic voltammetry（CV） and electrochemical impedance spectroscopy（EIS）.Their electrochemical performances were investigated by galvanostatic charge/discharge in terms of cycling performance and rate capability.The results show that the sam-ples have well regulated olivine type structures without any impurity peaks.Na-doping improves the conductivity and the Li＋ diffusion rate of composite materials and decreases the polarization of electrode,and enhances the cy-cling performance and rate capability effectively.Compared with LiFePO4/C,Li0.99Na0.01FePO4/C exhibits good electrode properties with discharge capacities of 147.6,126.4 and 105.1 mAh/g at 0.5C,2.0C and 5C rates,respec-tively.In addition,it has excellent cycle stability at different rates and good performance.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
2011年第6期625-630,共6页
Journal of Inorganic Materials
基金
国家自然科学基金(50474092)
广西省自然科学基金(2011GXNSFA018015)~~
