Bimetallic SnS2/NiS2@S-rGO nanocomposite with hierarchical flower-like architecture for superior high rate and ultra-stable half/full sodium-ion batteries

Bimetallic SnS2/NiS2 with hierarchical flower-like architecture wrapped by interconnected S-doped rGO 3D network (SnS2/NiS2@S-rGO) was synthesized by facile solvothermal strategy. The unique hierarchical flower-like architecture endows the whole electrode with sufficient Na+ active site and contact area to electrolyte, which could buffer the volume expansion and shorten the diffusion length of Na+. The interconnected S-rGO 3D network increases the whole electrochemical conductivity and accelerates the Na+ diffusion and electron transmission. In addition, the synergy effect of NiS2 and SnS2 components further enhanced the electrochemical performance. The obtained SnS2/NiS2@S-rGO electrode exhibits outstanding rate performance (330.4 mAh g−1 at 10 A g−1) and ultralong cycle stability (340.7 mAh g−1 after 5000 cycles at 2 A g−1) for sodium-ion half-cell. In addition, Na3V2(PO4)3@rGO//SnS2/NiS2@S-rGO sodium-ion full-cells are successfully assembled and deliver capacity of 472.8 mAh g−1 after 50 cycles at 0.1 A g−1. Ex-situ XRD, Raman spectra and HRTEM images, and a series of electrochemical analyses were employed to investigate the sodium-ion storage mechanism and ion diffusion kinetics of the SnS2/NiS2@S-rGO electrode. These results uncover the promising potential of SnS2/NiS2@S-rGO with hierarchical flower-like architecture toward SIBs.