Electrochemical performance of Li3V2(PO4)3/C cathode material using a novel carbon source

Polyethylene glycol (PEG, mean molecular weight of 10,000) has been used to prepare a Li3V2(PO4)3/C cathode material by a simple solid-state reaction. The Raman spectra shows that the coating carbon has a good structure with a low ID/IG ratio. The images of SEM and TEM show that the carbon is dispersed between the Li3V2(PO4)3 particles, which improves the electrical contact between the corresponding particles. The electronic conductivity of Li3V2(PO4)3/C composite is 7.0 × 10−1 S/cm, increased by seven orders of magnitude compared with the pristine Li3V2(PO4)3 (2.3 × 10−8 S/cm). At a low discharge rate of 0.28C, the sample presents a high discharge capacity of 131.2 mAh/g, almost achieving the theoretical capacity (132 mAh/g) for the reversible cycling of two lithium. After 500 cycles, the discharge capacity is 123.9 mAh/g with only 5.6% fading of the initial specific capacity. The Li3V2(PO4)3/C material also exhibits an excellent rate capability with high discharge capacities of 115.2 mAh/g at 1C and 106.4 mAh/g at 5C.