Single-Atom Catalysts as Promising Cathode Materials for Lithium-Sulfur Batteries

A major challenge toward the practical application of lithium-sulfur (Li-S) batteries is the lithium polysulphide (LiPS) shuttling, caused by the rapid LiPS migration in the electrolyte and slow reaction kinetics. Single-atom catalyst (SAC) materials hold the promise of strong LiPS binding to the cathode and improved reaction kinetics in Li-S batteries. In this study, we examine the electrocatalytic properties of four SAC materials with TM-N-4-C (TM = Co, Fe, V, and W) formation, from simulations based on the density functional theory. We study for the first time a W-based SAC as the Li-S cathode host and calculate the adsorption energy of five LiPS intermediates (Li2Sn, n = 1, 2, 4, 6, and 8). We explore the mechanism for the conversion of Li2S2 to Li2S and present the energy profiles based on the Gibbs free energy for the LiPS reaction pathway from S-8 to Li2S. V- and W-based SACs provide high LiPS binding, of up to 6.0 times of pristine graphene, and largely improved reaction kinetics by lowering the S dissociation barrier of the Li2S2 decomposition by similar to 2.5 times compared to pristine graphene. Our work provides a detailed investigation into the adsorption and conversion of LiPSs on SAC cathode hosts, highlighting their potential on improving the electrochemical performance of Li-S batteries and mitigating the LiPS shuttle effect.

Automated summary

This study investigates the electrocatalytic properties of single-atom catalyst (SAC) materials as cathode hosts for Li-S batteries, showing that V- and W-based SACs provide strong LiPS binding and significantly improved reaction kinetics, potentially enhancing the electrochemical performance of Li-S batteries.