Dual Carbon-Confined SnO 2 Hollow Nanospheres Enabling High Performance for the Reversible Storage of Alkali Metal Ions.

To explore a universal electrode material for the high-performance electrochemical storage of Li+ , Na+ , and K+ ions remains a big challenge. Herein, we propose a "trinity" strategy to coat the SnO2 hollow nanospheres using the dual carbon layer from the polydopamine-derived nitrogen-doped carbon and graphene. Thereinto, hollow structures with sufficient void space could buffer the volume expansion, whereas dual carbon-confined strategy could not only elastically prevent the aggregation of nanoparticle and ensure the structural integrity but also immensely improve the conductivity and endow high rate properties. Benefiting from the effective strategy and specific structure, the dual carbon-confined SnO2 hollow nanosphere (denoted as G@C@SnO2 ) can serve as the universal host material for alkali metal ions and enable their rapid and reversible storage. As expected, the resulting G@C@SnO2 as a universal anode material shows reversible alkali-metal-ion storage with high performance. We believe this that strategy could pave the way for constructing other metal-oxide-based dual carbon-confined high-performance materials for the future energy storage applications.