Solvent-Free Synthesis of Hollow Carbon Nanostructures for Efficient Sodium Storage

The structural characteristics of hollow carbon nanostructures (HCNs) result in intriguing physicochemical properties and various applications, especially for electrochemical energy storage applications. However, the currently solvent-based template methods to prepare HCNs are still far from meeting the facile, environment-friendly, and scalable demand. Herein, we explored a general and facile solvent-free block copolymer self-assembly approach to prepare various hollow hard carbon nanostructures, including hollow carbon nanofibers, hollow carbon Janus nanotadpoles, hollow carbon spheres, etc. It was found that the obtained HCNs possess abundant active sites, fast pathways for electrons/ions transport, and superior electronic conducting connectivity, which are promising for efficient electrochemical energy storage. Typically, the resultant hollow carbon nanofibers with a thick-walled tube deliver a high reversible capacity (431 mAh g^-1) and excellent rate performance (259 mAh g^-1 at 800 mA g^-1) for sodium ion storage. This intelligent solvent-free block copolymer self-assembly method would inspire the design of hollow hard carbon-based nanostructures for advanced applications in various energy conversion and storage.