Monodisperse CoSn2 and FeSn2 nanocrystals as high-performance anode materials for lithium-ion batteries.

Nanostructured metal alloys show great promise as replacement materials for graphite anodes, and could improve the energy and power density of present-day lithium-ion batteries (LIBs). Herein, we report a facile colloidal synthesis of CoSn2 and FeSn2 nanocrystals (NCs) via the reaction of Co or Fe NCs and SnCl2 in oleylamine under reducing conditions. Among our pure Sn NCs and mixtures of Co or Fe and Sn NCs, monodisperse CoSn2 nanoalloys showed considerably improved cycling stability. In particular, CoSn2 delivered a stable average capacity of 650 mA h g-1 for 5000 cycles at a high current density of 1984 mA g-1, which is among the highest reported cycling stabilities for Sn-based anode materials.