Effect of Transition Metal Ions Doping on the Performance of LiFePO4/C Cathode Material
YE Changfu, ZHENG Huiyuan, LAO Ming, ZHOU Wenzheng, GUO Jin, LI Guangxu
Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology,College of Physics Science and Technology, Guangxi University, Nanning 530004;
Abstract: By adding different transition metal acetates(manganese acetate, cobaltous acetate, nickel acetate, zinc acetate), LiFePO4/C composite materials were synthesized for lithium rechargeable batteries by high temperature solid-state reaction under the protection of argon, using Li2CO3, FeC2O4·2H2O, NH4H2PO4 , C6H12O6 (glucose) as raw materials. Effect of doping transition metal ions on crystal structure and performance of the sample was investigated by using X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, galvanostatic charge discharge and electrochemical impedance spectroscopy, cyclic voltammetry. The results indicated that LiFe0.9M0.1PO4/C(M=Mn, Co, Ni, Zn) and LiFePO4 have the same crystal structure of olivine-style. Doping transition metal ions can increase the reduction potential of LiFePO4/C, decrease the oxidation potential, reduce the distance between redox peaks, and improve the reversibility of the chemical reaction. The doped samples have a better discharge performance at 5C, especially LiFe0.9Ni0.1PO4/C which has the highest discharge specific capacity reaching 89 mAh/g.
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2017, Vol. 31 
