Li3V2(PO4)3 particles embedded in N and S Co-doped porous carbon cathode for high performance lithium storage：An experimental and DFT study

Abstract

Li3V2(PO4)3 (LVP)-coated with N and S co-doped carbon (NSC) is investigated by DFT calculation, suggesting that NSC significantly enhances electronic conductivity and lowers Li+ migration energy barrier in comparison to the LVP-embeded pristine carbon. To experimentally confirm the theoretical prediction, three types of LVP particles embedded N and S co-doped porous carbon (LVP@NSC) materials with various nitrogen and sulfur molar ratios (N:S=1:1, 1:2 and 2:1) were prepared by a facile freeze drying-assisted wet chemical route associated with a post-annealing process. When using as a cathode for lithium-ion battery (LIB), the designed LVP@NSC with N:S=1:2 exhibits outstanding high rate capacities of 124.4 and 107.85 mA h g-1 at 2 and 20 C in a voltage window of 3.0-4.3 V, respectively, and a ultralong cycle stability of 500 times at 20 C with remaining a reversible capacity of 100.22 mA h g−1 possibly due to its smallest charge transfer resistance and highest Li+ migration coefficiency, which is in good agreement with the theoretical rediction. This work not only reveals the critical role of interaction mechanism between NSC and LVP, but also offers great potentials for high energy density LIBs applications.