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

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.