A three-dimensional self-assembled SnS2-nano-dots@graphene hybrid aerogel as an efficient polysulfide reservoir for high-performance lithium–sulfur batteries

Abstract

Reliable sulfur cathodes hold the key to realizing high-performance lithium–sulfur (Li–S) batteries, yet the electrochemical inefficiency and instability arising from the poor conductivity of sulfur and lithium sulfide together with polysulfide diffusion present challenges. We present here a new three-dimensional graphene aerogel embedded with in situ grown SnS₂ nano-dots (SnS₂-ND@G) as an efficient sulfur host. First, benefiting from a highly conductive, hierarchically porous, and mechanically self-supported architecture, the SnS₂-ND@G aerogel enables the cathode to hold high sulfur content (75 wt%) and loading (up to 10 mg cm⁻²). Both values exceed most of the reported metal-compound-related cathode work (<60 wt% sulfur content and <3 mg cm⁻² sulfur loading) in the literature. Second, this work takes advantage of a facile one-pot self-assembly fabrication, effectively guaranteeing a homogeneous deposition of SnS₂ nano-dots in the graphene aerogel with a small amount of SnS₂ (16 wt%). It greatly overcomes the shortcomings of physical incorporation methods to make metal-compound/carbon substrates reported in previous studies. More importantly, by rationally combining the physical entrapment from graphene and chemical adsorptivity from SnS₂ nano-dots towards polysulfides, the SnS₂-ND@G aerogel demonstrates remarkably improved polysulfide-trapping capability and electrochemical stability. As a result, a high peak capacity of 1234 mA h g⁻¹, a high reversible capacity of 1016 mA h g⁻¹ after 300 cycles, exceptional rate capability (C/10 – 3C rates), and impressive areal capacity (up to 11 mA h cm⁻²) are achieved. This work provides a viable path to integrate a conductive graphene network and nano-sized SnS₂ as a promising cathode substrate for developing advanced Li–S batteries.