Two-phase interface hydrothermal synthesis of binder-free SnS2/graphene flexible paper electrodes for high-performance Li-ion batteries

Abstract

Free-standing graphene-based composite paper electrodes with various active materials have attracted tremendous interest for next-generation lithium-ion batteries (LIBs) due to advantages such as their light weight, excellent mechanical flexibility, and superior electrochemical performance. However, despite its high theoretical energy density, SnS₂ is rather difficult to composite with the graphene paper, because conventional reduction procedures for graphene oxide (GO) induce either decomposition or oxidation of SnS₂. Herein, a novel solid/gas two-phase interface hydrothermal process is reported to fabricate flexible free-standing SnS₂/graphene nanocomposite papers (SGP) assisted by a reducing and stabilizing agent thioacetamide aqueous solution. Such hydrothermal process not only successfully reduces SnS₂/graphene oxide paper (SGOP) to SGP, but more importantly, keeps intact the paper configuration as well as the phase stability of SnS₂. The as-prepared SGP electrode exhibits high reversible discharge capacity, outstanding cyclic stability and rate capability, which can be attributed to the synergistic effect of the conductive and flexible graphene matrix for accommodation of the volumetric changes of SnS₂ upon cycling and the planar SnS₂ nanospacers between the graphene layers introducing nanopores for penetration of electrolyte and inhibition of graphene nanosheets restacking. This report demonstrates a new strategy for more active materials with promising lithium storage properties joining the flexible graphene-based paper electrode family.