Ultra-small Na3V2(PO4)3 nanoparticles decorated MOFs-derived carbon enabling fast charge transfer for high-rate sodium storage

Na3V2(PO4)3 nanoparticles are decorated on MOF (ZIF-67) derived carbon via an impregnation followed by solid-phase sintering method. The ultra-small Na3V2(PO4)3 (~5 nm) particles and underlying mesoporous carbon framework enable fast charge transportation. A high sodium ion diffusion coefficient of 2.47 × 10−13 cm2 s−1 is achieved as measured by electrochemical impedance spectroscopy (EIS). The electron transfer resistance is also greatly reduced by the incorporation of mesoporous carbon. Therefore, such composite material demonstrates outstanding high rate performance as sodium ion battery cathode. Specifically, a discharge capacity of 84.6 mA h g−1 is recorded after 5000 cycles at a current density of 20C (1C = 117 mA g−1) corresponding to 86.3% of its initial capacity. The capacities still reach 74.5 and 62 mA h g−1 after 4500 cycles at high current densities of 30C and 50C, with Coulombic efficiency remains over 98%.