Yolk–shell tin phosphides composites as superior reversibility and stability anodes for lithium/sodium ion batteries

The rational design of nanostructure is crucial to achieving high-rate and long-term cycling performance for electrodes. Herein, the tin phosphide composites with yolk–shell nanostructure (SnxPy/NG) are designed and synthesized by one-step carbonization and phosphorization from the precursor of Sn6O4(OH)4/NG. The SnxPy/NG electrode with yolk–shell nanostructure shows energy storage properties superior to that of nanoclusters or nanoparticles. The void space in yolk–shell nanostructure relieves the huge volume expansion, and the unique phase hybridization of Sn4P3 and SnP0.94 promotes the reaction kinetics. Thus, SnxPy/NG delivers high-rate long-term cycling stability for Li-half cells (521.2 mA h g−1 maintained after 3000 cycles at 5.0 A g−1) and Na-half cells (203.1 mA h g−1 maintained after 300 cycles at 1.0 A g−1). The design strategy can promote the practical application of Sn-based phosphide and pave the way for designing and exploring other metal-based phosphide electrodes for energy storage.