Acta Phys. -Chim. Sin. ›› 2012, Vol. 28 ›› Issue (01): 100-104.doi: 10.3866/PKU.WHXB201228100

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Electrochemical Performance of Vanadium Modified LiFe0.5Mn0.5PO4/C Cathode Materials for Lithium-Ion Batteries

GONG Qiang, WANG Hong, LIAO Xiao-Zhen, MA Wei, HE Yu-Shi, MA Zi-Feng   

  1. Institute of Electrochemical and Energy Technology, Department of Chemical Engineering, School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai 200240, P. R. China
  • Received:2011-07-20 Revised:2011-10-13 Published:2011-12-29
  • Contact: LIAO Xiao-Zhen E-mail:liaoxz@sjtu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (21073120, 20773087, 21006063) and Science and Technology Commission of Shanghai Municipality, China (09DZ1203603, 10DZ1202702).

Abstract: Vanadium modified LiFe0.5Mn0.5PO4/C cathode materials with a nominal composition of (1-x)LiFe0.5Mn0.5PO4-xLi3V2(PO4)3/C (x=0, 0.1, 0.2, 0.25, 1) were prepared by a solid-state reaction using NH4VO3 as the vanadium source. The electrochemical performance of the LiFe0.5Mn0.5PO4-based compounds improved upon vanadium modification. The 0.8LiFe0.5Mn0.5PO4-0.2Li3V2(PO4)3/C (LFMP-LVP/C) sample exhibited the highest discharge capacity of 141 mAh·g-1 at 0.1C rate. X-ray diffraction analyses revealed a dual phase of the LFMP-LVP/C composite with the coexistence of an olivine-type LiFe0.5Mn0.5PO4/C phase and a NASICON-type Li3V2(PO4)3 phase. Energy dispersive X-ray spectroscopy (EDS) analysis indicates a uniform distribution of Fe, Mn, V, and P in the composite. The electronic conductivity of LFMP-LVP was found to be 2.7×10-7 S·cm-1, which is much higher than the value (1.9×10-8 S·cm-1) of LiFe0.5Mn0.5PO4 and similar to the value (2.3 × 10-7 S·cm-1) of pure Li3V2(PO4)3. Vanadium modification remarkably reduced the electrode polarization of the LFMP-LVP/C cathode during the charge-discharge procedure. This suggests that vanadium modification is an effective method to improve the electrochemical performance of olivine-type cathode materials.

Key words: Lithium-ion battery, LiFe0.5Mn0.5PO4, Li3V2(PO4)3-modified, Cathode material

MSC2000: 

  • O646