Elaborate interface design of SnS2/SnO2@C/rGO nanocomposite as a high-performance anode for lithium-ion batteries

Abstract

The practical application of Sn-based anode materials is limited by their low electrical conductivity and large volume expansion during cycling. To overcome these challenges, a novel SnS2/SnO2@C/rGO nanocomposite is synthesized by in-situ H2O2 oxidation of SnS2@C/rGO that is prepared via a hydrothermal reaction using SnCl2, thiourea, L-ascorbic acid and GO as the reactants. Tightly contacted SnS2/SnO2 heterostructured nanoparticles are encapsulated by the amorphous carbon derived from L-ascorbic acid, which are further firmly anchored on the rGO sheets through the chemical interactions between the hydroxyl groups of L-ascorbic acid and hydroxyl/carbonyl groups of rGO. The amorphous carbon layer can act as a spacer to prevent the stacking of rGO sheets to retain the ion transport pathway. Meanwhile, the N and S heteroatoms are co-doped into the rGO sheets by using thiourea as N and S sources, which can enhance the electrical conductivity and provide more active sites for Li+ insertion/extraction. The obtained nanocomposite exhibits a specific capacity of 689 mA h g−1 after 300 cycles at a current density of 0.1 C (1 C = 783 mA g−1) and a moderate capacity of 619 mA h g−1 up to 500 cycles at a large current rate of 0.5 C.