Stannous ions reducing graphene oxide at room temperature to produce SnOx-porous, carbon-nanofiber flexible mats as binder-free anodes for lithium-ion batteries

Abstract

Tin oxides with high theoretical capacities as anodes for lithium-ion batteries always suffer from the electrical disconnect issue of active materials owing to huge volume changes. In this work, flexible mats composed of ultra-small SnO_x nanoparticles, graphene, and carbon fibers are synthesized by reducing graphene oxide with stannous ions at room temperature following treatments. SnO_x nanoparticles, including SnO and SnO₂, with diameters of approximately 4 nm are embedded in the matrix composed of carbon fiber and graphene to form composite fibers that are woven into flexible mats without any binders. As binder-free anodes for lithium-ion batteries, SnO_x–graphene–carbon fiber mats can deliver a high reversible capacity of 545 mA h g⁻¹ after 1000 cycles at a current density of 200 mA g⁻¹, which is much better than those of SnO_x–carbon fiber mats. The improved performance of SnO_x–graphene–carbon fiber mats can be attributed to the ultra-small size of SnO_x nanoparticles and the double protection of both graphene and carbon fibers.