Sn@CNT nanostructures rooted in graphene with high and fast Li-storage capacities.

Development of materials with carefully crafted nanostructures has been an important strategy for the next-generation lithium-ion batteries to achieve higher capacity, longer cycle life, and better rate capability. Graphene-based and Sn-based anode materials are promising anodes with higher capacities than graphite; however, most of them exhibit fast capacity fading at prolonged cycling and poor rate capability. This paper reports a hierarchical Sn@CNT nanostructure rooted in graphene, which exhibits larger than theoretical reversible capacities of 1160-982 mAh/g in 100 cycles at 100 mA/g and excellent rate capability (828 mAh/g at 1000 mA/g and 594 mAh/g at 5000 mA/g). The excellent electrochemical performances compared to graphene/Sn-based anodes have been attributed to the efficient prevention of graphene agglomeration by Sn@CNT decoration and the increased electrochemical activities of Sn by CNT shell protection and GNS support.