Synthesis and electrochemical properties of Li9V3 − xTix(P2O7)3(PO4)2/C compounds via wet method for lithium-ion batteries

A series of Ti4+-doped Li9V3 − xTix(P2O7)3(PO4)2/C compounds have been prepared by using wet method. X-ray diffraction measurement shows that single phase region can be expressed as x ≤ 0.10. The effects of substitution of Ti for V on the electrochemical properties of Li9V3 − xTix(P2O7)3(PO4)2 compounds have been studied. Our investigations show that Ti doping can improve the electrochemical performance. The Li9V2.95Ti0.05(P2O7)3(PO4)2/C exhibits the best cycle performance and the highest first discharge capacity of 120.7 mAh g−1 at 0.2 C. The electrochemical impedance spectroscopy indicates that the charge transfer resistance initially decreases with x and then for x > 0.05 increases monotonically with Ti4+ content.