Three‐Dimensional Graphene Network Decorated with Highly Symmetrical Cuboid Na3V2(PO4)2F3 Particles: High Rate Capability and Cycling Stability for Sodium‐Ion Batteries

Na3V2(PO4)2F3 (NVPF) has captured significant heed for cathode materials of sodium‐ion battery (SIB), owing to its stable three‐dimensional (3D) structure channel that can accommodate Na+ diffusion. However, NVPF is still facing with a major challenge in terms of the electrochemical performance, owing to its uncontrollable morphology. Hence, it was fabricated by using a two‐step hydrothermal method, whereby NVPF cuboid particles of homogenous morphology and highly structural symmetry could anchor on the three‐dimensional graphene network (GN) structure to form NVPF@GN. The affiliation between the morphology and performance of the NVPF@GN was further probed by manipulating the morphology of the NVPF under diverse heat treatment temperatures. When the temperature reaches 480 °C, NVPF@GN manifests prolonged cyclability (the capacity fading rate of 0.01 % cycle−1 at 0.5 C during 300 cycles) and it shows outstanding rate performance (when the rate is reset to 0.5 C, the capacity is 107 mAh g−1 and capacity retention is 99 %), which can be ascribed to the high structural symmetry of NVPF@GN. These results indicate that NVPF@GN cuboids can be used as a prospective cathode material for SIBs.