Improving the battery performance of LiVPO₄F by chromium doping

Polyanion LiVPO₄F has been recently recognized as a promising high energy cathode material for next generation rechargeable lithium batteries. With the aim of performance advancement in this paper, 3 at.% chromium are used to dope LiVPO₄F during carbothermal reduction synthesis. Rietveld refinement of X-ray diffraction pattern indicates that most of the chromium favors occupying the lithium site. Energy dispersive X-ray spectrum on selected area of the particle further demonstrates successful Cr doping into LiVPO ₄F. Both the rate capability and cycling performance of LiVPO ₄F are found noticeably improved possibly due to the stabilized crystalline structure and increased electric conductivity by Cr doping. The specific discharge capacities at C/24, C/5, 1 C and 8 C rates are 144.3, 135.1, 108.5 and 89.6 mA h g^-1, respectively. Moreover, it delivers a capacity of 128.7 mA h g^-1 at C/2 with the retention of 88.2% after 100 cycles.