5. Single Source Precursor Route to Carbon Coated Li₃V₂(PO₄)₃ for Cathode and Anode Applications in Lithium Ion Batteries

This chapter deals with the synthesis of monoclinic Li₃V₂(PO₄)₃ using the MOPOF material, [Li₂(VO)₂(HPO₄)₂(C₂O₄)]·6H₂O as a single source precursor. Thermal decomposition of the oxalatophosphate precursor at 800 °C in argon atmosphere resulted in a Li₃V₂(PO₄)₃–V₂O₃ composite. Carbon coating of the particles were carried out by addition of sucrose to the precursor prior to thermal decomposition, to achieve better electronic conductivity. The carbon coated sample exhibits a large BET surface area of 75 m² g⁻¹ while the pristine sample has a lesser surface area of 5.4 m² g⁻¹. In the voltage range of 2.5–4.3 V, carbon coated sample shows a reversible capacity of 132 mAh g⁻¹ at 0.1 C current rate with good capacity retention. In addition, it shows good rate capability with 56 mAh g⁻¹ obtained at a high current rate of 20 C. In comparison, the pristine sample shows inferior electrochemical performance with capacity fading. The carbon coated sample was also investigated as an anode material. It exhibits a good reversible capacity of 125 mAh g⁻¹ when cycled in the voltage range of 1–3 V at a current density of 50 mA g⁻¹ (0.4 C).