Sc3+-doping effects on porous Li3V2(PO4)3/C cathode with superior rate performance and cyclic stability

An enhanced sol-gel combustion method was used to synthesize different porous Sc3+-doped Li3V2-xScx(PO4)3/C (x = 0.00, 0.05, 0.10 and 0.15) compounds. The substitution of Sc3+ into the V3+ sites of Li3V2-xScx(PO4)3/C expands the lattice volume along with the enlargement of Li+ diffusion channel, which is beneficial for Li+ transportation and ionic conductivity improvement. Besides, the Sc3+ doping content exhibits a great impact on the morphology of Li3V2-xScx(PO4)3/C composite. The pristine Li3V2(PO4)3/C are constituted of porous particles and nanorods, and the ratio of nanorods to particles can be controlled by adjusting the amount of Sc3+ doping since the ratio of nanorods to particles decreases with increasing Sc3+ doping content. When Sc3+ doping content increases to a certain level (x = 0.15, Li3V1.85Sc0.15(PO4)3/C), the nanorods are hardly seen. Li3V1.90Sc0.10(PO4)3/C with higher tapped density, better reversibility, smaller resistance and larger Li+ diffusion coefficient demonstrates outstanding rate performance and cyclic stability, together with high specific discharge capacities of 130.2 and 92.9 mAh g−1 at 0.5 and 20 C, respectively. Furthermore, a superior specific discharge capacity of 85.8 mAh g−1 was retained at 20 C following 1000 cycles. Overall, a novel approach for the preparation of high-performance Li3V2-xScx(PO4)3/C cathodes with different morphologies for lithium-ion batteries is provided.