Uniform yolk–shell Sn₄P₃@C nanospheres as high-capacity and cycle-stable anode materials for sodium-ion batteries

Uniform yolk–shell Sn₄P₃@C nanospheres were facilely synthesized via a top-down phosphorized route with yolk–shell Sn@C nanospheres as the precursor. As anode materials for Na-ion batteries, they exhibit very high reversible capacity (790 mA h g⁻¹), superior rate capability (reversible capabilities of 720, 651, 581, 505, and 421 mA h g⁻¹ at 0.2C, 0.4C, 0.8C, 1.5C, and 3C, respectively) and stable cycling performance (a high capacity of 360 mA h g⁻¹ at 1.5C after long 400 cycles).