Promising Dual-Doped Graphene Aerogel/SnS₂ Nanocrystal Building High Performance Sodium Ion Batteries

Abstract

We report the effort in designing layered SnS₂ nanocrystals decorated on nitrogen and sulfur dual-doped graphene aerogels (SnS₂@N,S-GA) as anode material of SIBs. The optimized mass loading of SnS₂ along with the addition of nitrogen and sulfur on the surface of GAs results in enhanced electrochemical performance of SnS₂@N,S-GA composite. In particular, the introduction of nitrogen and sulfur heteroatoms could provide more active sites and good accessibility for Na ions. Moreover, the incorporation of the stable SnS₂ crystal structure within the anode results in the superior discharge capacity of 527 mAh g^-1 under a current density of 20 mA g^-1 upon 50 cycles. It maintains 340 mAh g^-1 even the current density is increased to 800 mA g^-1. Aiming to further systematically study mechanism of composite with improved SIB performance, we construct the corresponding models based on experimental data and conduct first-principles calculations. The calculated results indicate the sulfur atoms doped in GAs show a strong bridging effect with the SnS₂ nanocrystals, contributing to build robust architecture for electrode. Simultaneously, heteroatom dual doping of GAs shows the imperative function for improved electrical conductivity. Herein, first-principles calculations present a theoretical explanation for outstanding cycling properties of SnS₂@N,S-GA composite.