Heterostructured Sn:SnO2 Nanodots for High-Performance Li-S Batteries with Kinetics-Enhanced Cathode and Dendrite-Free Anode

Abstract

The practical application of lithium-sulfur batteries is limited by polysulfide shuttling and sluggish reaction kinetics at the cathode, as well as uncontrollable dendrite growth at the anode. In this study, it is demonstrated that heterostructured Sn:SnO2 nanodots anchored on reduced graphene oxide can serve as a bifunctional host for both sulfur and lithium, effectively addressing these challenges. The Sn:SnO2 nanodots exhibite high adsorption capability due to SnO2 and enhanced electron transfer characteristics attributed to metallic Sn. This synergistic effect suppresses the shuttle effect and improves reaction kinetics at the cathode. Additionally, the high lithiophilicity of Sn:SnO2 facilitates uniform lithium deposition, enabling a dendrite-free lithium anode. As a result, lithium-sulfur batteries utilizing this novel host exhibit an excellent rate capability of 670 mAh g-1 at 4C and upgraded cycling stability with 81% capacity retention over 500 cycles at 1C. Even under challenging conditions-including high sulfur loading (5.5 mg cm-2), lean electrolyte (6.0 mu L mg-1), and a low negative-to-positive capacity ratio of 1.4-practical cells delivered a high capacity of 5.04 mAh cm-2. This work provides a promising and effective strategy for simultaneously addressing issues associated with both sulfur and lithium electrodes, thereby accelerating the practical deployment of lithium-sulfur batteries.