HETEROSTRUCTURE OF REDUCED GRAPHENE OXIDE SUPPORTED TIN (IV) SULFIDE NANOPETALS AS AN ANODE MATERIAL FOR SODIUM/POTASSIUM-ION BATTERIES: EVIDENCE FOR THE FORMATION OF C-S BOND

Abstract

Anodes that engage in conversion as well as alloying reactions are highly attractive candidates for sodium/potassium-ion batteries (SIBs and PIBs) because of their high theoretical specific capacities. Herein, Tin sulphide@reduced graphene oxide (SnS2 nanopetal@rGO) composite material is investigated as an advanced anode material for SIBs and PIBs. In this work, a simple hydrothermal synthesis of ultrathin SnS2 nanopetals covalently decorated on the surface of rGO is demonstrated as an anode material for SIBs and PIBs. The as prepared SnS2@rGO displays an initial charge capacity of 749 (at 0.2 A g−1) and 852 mAh g−1 (at 0.1 A g−1) for SIBs and PIBs respectively. The SnS2@rGO hybrid exhibited excellent cycle life which is attributed to the introduction of rGO in the composite as well as the in-built formed C-S bond. Moreover, the rGO matrix, firmly anchored with C–S bonds, envelops the outer SnS2, effectively inhibiting direct contact between SnS2 and the electrolyte. These combined effects contribute to impede the irreversible conversion of sulfur to sulfite, thus ensuring excellent structural stability throughout electrochemical cycling. The well-engineered nanoarchitecture not only guarantees the fast electrode kinetics, but also confirms excellent pseudo capacitance contribution during repetitive cycles which is confirmed by kinetic studies. Thus, SnS2@rGO is found to be a most promising electrode for sodium/potassium-ion batteries.