FeSn5@Graphene Anodes for Li-Ion and Na-Ion Batteries

Abstract

Intermetallic FeSn5 new phase has emerged as promising alternative material for application in lithium ion batteries (LIBs) due to its highest theoretical capacity of 929 mAh g−1 for the reported M(electrochemically inactive)-Sn intermetallic anodes. However, the cycling life and rate capacity of FeSn5 electrode materials still remains a great challenge. Herein, we report for the first time a facile strategy to synthesize such well-organized composite of nano-sized FeSn5 anchored on conducting graphene sheets as an advanced anode material for Li-ion and Na-ion batteries. The in situ synthesized FeSn5@graphene composite exhibits excellent cyclic stability and good rate capability which was ascribed to the structure of homogeneous distribution of FeSn5 nanospheres on graphene sheets that can improve electrical conductivity and accommodate structural stress due to its good conductivity, high surface area and mechanical flexibility. Further, the higher capacities of FeSn5@graphene composites in LIBs than that in SIBs is ascribed to the large Na-ion radius, resulting in slow Na-ion diffusion and large volume change upon sodium insertion/extraction reactions in SIBs. For comparison, bare graphene and FeSn5 nanocrystals were also prepared and investigated in detail.