Rambutan-Inspired Yolk-Shell Silica@Carbon Frameworks from Biomass for Long-Life Anode Materials

Abstract

SiO2 is regarded as one of the most promising anode materials for Li‐ion batteries due to its high capacity, low cost and other merits. However, the poor conductivity and the volume change are still hindering its practical applications. In this work, a rambutan‐inspired structure is designed to fabricate amorphous SiO2@N, P co‐doped porous carbon frameworks from biomass. The carbon shell could connect with each other, providing good conductivity. After partially etching of the SiO2, the yolk‐shell structure could buffer the volume changes of SiO2 during the charge/discharge processes without destroying the conducting shell. Besides, N, P doping and graphite nano crystallites in the frameworks could also offer more active sites for Li+ storage. As a result, the composite can not only exhibit excellent rate performance nearly 300 mAh g−1 at a current density of 2000 mA g−1, but also deliver a surprisingly stable reversible capacity of 373 mAh g−1 over 1000 cycles at the current density of 500 mA g−1 with the Coulombic efficiency beyond 99%. Considering the facile preparation and satisfactory lithium storage abilities, this composite design could be able to extend for practical battery application.