SnS/Fe7S8 heterojunction embedded in three-dimensional N, S co-doped carbon nanosheets as anode material for sodium-ion batteries with long-term cycle life

Abstract

Bimetallic sulfide SnS/Fe7S8 nanoparticles were embedded in three-dimensional N, S co-doped carbon nanosheets (SnS/Fe7S8/NS-CNs composite) have been synthesized via a simple method. Dense SnS/Fe7S8 nanoparticles were prepared using the electropositive Fe(OH)33+ colloid to adsorb SnO32- ions. And the carbon matrix was obtained with polyvinylpyrrolidone as the carbon source. The SnS/Fe7S8/NS-CNs composite as the sodium-ion batteries (SIBs) anode shows excellent cycle and rate performance, it deliver a high first discharge/charge capacity of 873/559.2 mAh g−1 at 0.2 A g−1 and a high maintained capacity 305.2 mAh g−1 after long cycle (over 2000 cycles) at 1.0 A g−1. Benefiting from bimetallic sulfide heterostructure, which can boost the electron/Na+ transfer kinetics and the SnS/Fe7S8 particle breaking avoidance by the 3D carbon matrix with dense carbon nanosheets, caused SnS/Fe7S8/NS-CNs electrode get outstanding electrochemical properties. In addition, the electrochemical conductivity was improved by the N, S co-doped 3D carbon nanosheet matrix. Thus, the SnS/Fe7S8/NS-CNs composite is a potential anode material for high performance SIBs.