High quality NMP exfoliated graphenenanosheet–SnO2 composite anode material for lithium ion battery

Abstract

A graphene nanosheet–SnO₂ (GNS–SnO₂) composite is prepared using N-methylpyrrolidone as a solvent to exfoliate graphene from graphite bar with the aid of CTAB by single phase co-precipitation method. The synthesized composites has been characterised physically by powder XRD which confirms the formation of the composite tetragonal SnO₂ crystal system with the low intense broad 002 plane for GNS. The sandwiched morphology of GNS–SnO₂ and the formation of nanosized particles (around 20 nm) have been confirmed by SEM and TEM images. The presence of sp² carbon in the GNS is clear by the highly intense G than D band in laser Raman spectroscopy analysis; furthermore, a single chemical shift has been observed at 132.14 ppm from solid-state ¹³C NMR analysis. The synthesized composite has been electrochemically characterized using charge–discharge and EIS analysis. The capacity retentions at the end of the first 10 cycles is 57% (100 mA g⁻¹ rate), the second 10 cycles is 77.83% (200 mA g⁻¹), and the final 10 cycles (300 mA g⁻¹) is 81.5%. Moreover the impedance analysis clearly explains the low resistance pathway for Li⁺ insertion after 30 cycles when compared with the initial cycle. This superior characteristic of GNS–SnO₂ composite suggests that it is a promising candidate for lithium ion battery anode.