Acta Phys. -Chim. Sin. ›› 2015, Vol. 31 ›› Issue (8): 1513-1520.doi: 10.3866/PKU.WHXB201506082

• ELECTROCHEMISTRY AND NEW ENERGY • Previous Articles     Next Articles

Triple-Cation-Doped Li3V2(PO4)3 Cathode Material for Lithium Ion Batteries

Xiao-Fei. SUN1,2,*(),You-Long. XU1,2,Xiao-Yu. ZHENG1,2,Xiang-Fei. MENG1,2,Peng. DING1,2,3,Hang. REN1,2,Long. LI1,2   

  1. 1 Electronic Materials Research Laboratory, Key Laboratory of the Ministry of Education, Xi'an Jiaotong University, Xi'an 710049, P. R. China
    2 International Center for Dielectric Research, Xi'an Jiaotong University, Xi'an 710049, P. R. China
    3 Staff Room of Power, Wuhan Ordnance Non-Commissioned Officer Academy, Wuhan 430075, P. R. China
  • Received:2015-02-03 Published:2015-08-12
  • Contact: Xiao-Fei. SUN E-mail:xfsunxjtu@mail.xjtu.edu.cn
  • Supported by:
    the Natural Science Foundation of China(21343011);Natural Science Foundation of Shaanxi Province, China(2014JQ2-2007);111 Project(B14040);Fundamental Research Funds for the Central Universities of China(xjj2014044)

Abstract:

Li3V2(PO4)3 and its triple-cation-doped counterpart Li2.85Na0.15V1.9Al0.1(PO4)2.9F0.1 were prepared by a conventional sol-gel method. The effect of Na-Al-F co-doping on the physicochemical properties, especially the electrochemical performance of Li3V2(PO4)3, were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), Raman spectroscopy, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), galvanostatic charge/discharge, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). It was found that combined with surface coating from residual carbon, this triple-cation co-doping stabilizes the crystalline structure of Li3V2(PO4)3, suppresses secondary particle agglomeration, and improves the electric conductivity. Moreover, reversible deinsertion/insertion of the third lithium ion at deeper charge/discharge is enabled by such doping. As a consequence, the practical electrochemical performance of Li3V2(PO4)3 is significantly improved. The specific capacity of the doped material at a low rate of 1/9C is 172 mAh·g-1 and it maintains 115 mAh·g-1 at a rate of 14C, while the specific capacities of the undoped sample at 1/9C and 6C are only 141 and 98 mAh·g-1, respectively. After 300 cycles at 1C rate, the doped material has a capacity of 118 mAh·g-1, which is 32.6% higher than that of the undoped counterpart. It is also noteworthy that the multiplateau discharge curve of Li3V2(PO4)3 transforms to a slope-like curve, indicating the possibility of a different lithium intercalation mechanism after this co-doping.

Key words: Lithium vanadium phosphate, Doping, Sol-gel, Cathode material, Lithiumion battery, E nergy storage

MSC2000: 

  • O646