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

Abstract

An enhanced sol-gel combustion method was used to synthesize different porous Sc 3+ -doped Li 3 V 2-x Sc x (PO 4 ) 3 /C (x = 0.00, 0.05, 0.10 and 0.15) compounds. The substitution of Sc 3+ into the V 3+ sites of Li 3 V 2-x Sc x (PO 4 ) 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 Sc 3+ doping content exhibits a great impact on the morphology of Li 3 V 2-x Sc x (PO 4 ) 3 /C composite. The pristine Li 3 V 2 (PO 4 ) 3 /C are constituted of porous particles and nanorods, and the ratio of nanorods to particles can be controlled by adjusting the amount of Sc 3+ doping since the ratio of nanorods to particles decreases with increasing Sc 3+ doping content. When Sc 3+ doping content increases to a certain level (x = 0.15, Li 3 V 1.85 Sc 0.15 (PO 4 ) 3 /C), the nanorods are hardly seen. Li 3 V 1.90 Sc 0.10 (PO 4 ) 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 Li 3 V 2-x Sc x (PO 4 ) 3 /C cathodes with different morphologies for lithium-ion batteries is provided.