Unlocking High-Rate Sodium Storage in NaFePO₄ via Graphene-Driven Cross-Scale Structural Regulation

Sodium iron phosphate (NaFePO₄) is a promising cathode material for sodium-ion batteries (SIBs) due to its low cost and high energy density. However, it suffers from inherent limitations such as poor electronic conductivity, sluggish ion kinetics, and electrochemical inertness of its crystalline phases. To overcome these drawbacks, a graphene-driven cross-scale structural regulation strategy is developed. Reduced graphene oxide (rGO) is integrated with NaFePO₄ to enhance electron conductivity through its interconnected carbon network at the microscale. More importantly, at the nanoscale, rGO inhibits excessive particle growth, and at the atomic scale, it promotes amorphous active phase formation via interfacial interactions. As a result, the rGO-composite NaFePO₄ samples exhibit a high discharge capacity of 122.7 mAh g^-1 at 1C and long-term cycling stability (84.6% capacity retention after 1000 cycles at 10C). This work establishes rGO-mediated multiscale engineering as a universal paradigm for revitalizing polyanionic cathodes in energy storage applications.