Tailored Yolk–Shell Sn@C Nanoboxes for High‐Performance Lithium Storage

A yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The void space is engineered to fit the volume expansion of Sn during cycling. It is demonstrated that the shell thickness of carbon nanobox has substantial influence on both nanostructures and the electrochemical performance. With an optimized shell thickness, a high reversible capacity of 810 mA h g−1 can be maintained after 500 cycles, corresponding to 90% retention of the second discharge capacity. For Sn@C materials with either thinner or thicker carbon shells, significant capacity decay or a decreased specific capacity are observed during cycling. The present study sheds light on the rational design of nanostructured electrode materials with enhanced electrochemical performance for next‐generation lithium ion batteries. A novel yolk–shell Sn@C nanobox composite with controllable structures has been synthesized using a facile approach. The generation of metallic Sn together with the void space and the conversion of polymer to carbon are simultaneously completed in one step. Importantly, with an optimized carbon shell thickness, the composite exhibits high specific capacity, good rate performance, and exceptional cycling stability.