Synthesis and electrochemical properties of Co-doped Li_9V_3(P_2O_7)_3(PO_4)_2/C as cathode materials for lithium-ion batteries

摘要

A series of Co-doped Li_9V_3 ? xCox(P_2O_7)_3(PO_4)_2/C (x= 0.00-0.10) compounds have been prepared by sol-gel method and the Rietveld refinement results indicate that pure-phase Li_9V_(3 ? x)Co_x(P_2O_7)_3(PO_4)_2/C (x = 0.00- 0.10) compounds with trigonal structure can be obtained. Their electrochemical performance has been investigated and the results showthat, although the initial specific capacity decreased with Co doping at a lower current rate, both cycle performance and rate capability have excited improvement with proper Co-doping content. Li_(9-) V_(2.96)Co_(0.04)(P_2O_7)_3(PO_4)_2/C compound presents the best cyclic ability and rate performance. The enhancement of cyclic ability and rate performancemay be attributed to enhanced specific surface area and improvedlithium-ion diffusion during the proper amount of Co-doping (x = 0.04) in V sites.