Accelerating Sulfur Conversion Kinetics by Topological Semimetal Electrocatalysts Pd3Sn for High-performance Li-S Batteries

Abstract

The shuttle effect and sluggish reaction kinetics of soluble lithium polysulfides (LiPSs) significantly impede the practical application of lithium-sulfur (Li-S) batteries. Topological semimetals (TSMs) offer a promising solution to these challenges due to their unique topological surface states. This study synthesizes reduced graphene oxide (rGO)-loaded Pd₃Sn TSMs (Pd₃Sn@rGO) that are prepared by the NaBH₄ reduction method. The obtained Pd₃Sn@rGO composite has a notably stronger adsorption capability for LiPSs than pure rGO verified by adsorption experiments and density functional theory (DFT) calculations. The topological surface states of Pd₃Sn facilitate the acceptance of electrons from Li₂S₆ during the adsorption process, thereby enhancing adsorption and accelerating redox reactions. Furthermore, Li₂S deposition experiments confirm the effective catalytic role of Pd₃Sn@rGO in the nucleation process of Li₂S. Consequently, Li-S batteries with Pd₃Sn@rGO modified separators showcase exceptional rate performance across various current densities along with impressive cycling stability (decay rate of 0.0598% per cycle at 1C). This work highlights the capability of Pd₃Sn in catalyzing sulfur redox reactions and underscores the potential of other TSM electrocatalysts in enhancing the performance of Li-S batteries.