Effect of Ti-doping on the electrochemical performance of lithium vanadium(III) phosphate

Carbon-coated and titanium-substituted lithium vanadium phosphate composites have been successfully prepared through a sol-gel method followed by solid-state reaction under argon. Li3V1.9Ti0.1(PO4)3-C (LVT10PC) and Li3V1.85Ti0.15(PO4)3-C (LVT15PC) were investigated using X-ray powder diffraction, thermal analysis, transmission electron microscopy, cyclic voltammetry, and galvanostatic tests. Different models for the solid solution mechanism in this system are discussed. Electrochemical tests, at a charge-discharge rate of 0.2 C, in the range 2.8–4.4 V show that LVT10PC delivers the highest discharge capacity of 121 mA h g−1 and declines to 115.7 mA h g−1 up to the 60th cycle, corresponding to a 4.4 % loss. At low levels, titanium substitution is found to increase initial discharge capacity compared to the carbon-coated unsubstituted system (LVPC). Further substitution is found to have detrimental effects on initial discharge capacity and cycling behaviour.