Preparation and electrochemical properties of Cr-doped Li9V3(P2O7)3(PO4)2 as cathode materials for lithium-ion batteries

Cr-doped Li9V3−xCrx(P2O7)3(PO4)2 (x = 0.0–0.5) compounds have been prepared using sol–gel method. The Rietveld refinement results indicate that single-phase Li9V3−xCrx(P2O7)3(PO4)2 (x = 0.0–0.5) with trigonal structure can be obtained. Although the initial specific capacity decreased with Cr content at a lower current rate, both cycle performance and rate capability have excited improvement with moderate Cr-doping content. Li9V2.8Cr0.2(P2O7)3(PO4)2 compound presents the good electrochemical rate and cyclic ability. The enhancement of rate and cyclic capability may be attributed to the optimizing particle size, morphologies, and structural stability during the proper amount of Cr-doping (x = 0.2) in V sites.

► The Cr-doped Li9V3(P2O7)3(PO4)2 compounds were successfully prepared by the sol–gel method.
► Both cycle performance and rate capability of Li9V3−xCrx(P2O7)3(PO4)2 have excited improvement with moderate Cr-doping content.
► Li9V2.8Cr0.2(P2O7)3(PO4)2 compound presented more better electrochemical rate and cyclic ability.