One-Step Solvothermal Route to Sn₄P₃-Reduced Graphene Oxide Nanohybrids as Cycle-Stable Anode Materials for Sodium-Ion Batteries

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Sn₄P₃, owing to its high theoretical volumetric capacity, good electrical conductivity, and relatively appropriate potential plateau, has been recognized as an ideal anode for sodium-ion batteries (NIBs). However, the current synthetic routes for Sn₄P₃-based nanohybrids typically involve foreign-template-based multistep procedures, limiting their large-scale production and applications in NIBs. Using commercial red phosphorus as the phosphorus source and nontoxic ethanolamine as the solvent, we herein report a facile and scalable solvothermal protocol for the one-step preparation of Sn₄P₃-reduced oxide graphene (denoted as Sn₄P₃-rGO) hybrid materials. Benefiting from the novel strategy and elaborate design, ultrasmall Sn₄P₃ nanoparticles (2.7 nm on average) are homogeneously anchored onto rGO. The high conductivity of the rGO network and the short electron/ion diffusion path of ultrasmall Sn₄P₃ nanoparticles give the Sn₄P₃-rGO hybrid high capacities and stable long-term cyclability. Specifically, the optimized Sn₄P₃-rGO hybrid displays a remarkable reversible capacity of 663.5 mA h g⁻¹ at a current density of 200 mA g⁻¹, ultralong-term cycle life (301 mA h g⁻¹ after 2500 cycles at a high current density of 2000 mA g⁻¹), and excellent rate capability, presenting itself as a highly promising anode material for NIBs.