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

Abstract

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.