One-step synthesis of hollow structured Si/C composites based on expandable microspheres as anodes for lithium ion batteries

•Hollow Si/C composites were obtained from expandable microspheres (EMs) and Si NPs.•EMs were employed as self-template carbon precursors.•This method is one-step, environment-friendly and scalable.•A capacity of 684.6 mAh g− 1 (80% retention) at 50 cycles, 300 mA g− 1 was achieved.

Si/C composites of carbon hollow structures loaded with Si nanoparticles (NPs) (Si/C-HSs) were prepared by one-step pyrolysis of a mixture of Si NPs and expandable microspheres (EMs). For the Si/C-HSs, hollow carbon shells with rough surfaces were formed by directly carbonizing the polymer shells of EMs, and the Si NPs fell into the void space or were loaded on the rough surfaces of the carbon shells. The EM-based carbon shells accommodated the volume expansion of the Si NPs and improved the electrical conductivity of the composites. As a result, the Si/C-HSs exhibited a high capacity (initial reversible capacity: 854.4 mAh g− 1 at 300 mA g− 1), stable cycling performance (capacity retention: 80% after 50 cycles), and excellent rate capability.

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