Facile synthesis of sulfur coated SnO₂-graphene nanocomposites for enhanced lithium ion storage

A simple and low temperature hydrothermal synthesis approach has been developed to prepare sulfur coated SnO₂-graphene nanocomposites as an anode material for lithium-ion batteries. The electrochemical performance of the composites was characterized by galvanostatic charge-discharge tests, cyclic voltammetry and electrochemical impedance spectroscopy measurements. Results show that the composite material exhibits a reversible capacity of 819 mAh g^-1 after 200 cycles at 500 mA g^-1 and an excellent rate capability of 580 mAh g^-1 at a high current density of 4000 mA g ^-1. The extraordinary performance could be ascribed to the positive synergistic effect of the combination of the nanosized particles of SnO ₂, the excellent conductivity of graphene and the effects of the coating layer of sulfur.