Understanding the Electrocatalytic Trend of Sulfur Reduction Reaction and Design Rules of Advanced Electrocatalysts for Li–S Batteries

Despite the great potential of using electrocatalysts to improve the performance of lithium–sulfur (Li–S) batteries, a deficient understanding of the electrocatalytic trends in the sulfur reduction reaction with respect to the adsorption energy of sulfur active species and a lack of descriptors to estimate electrocatalytic activity limit the design of advanced electrocatalysts for Li–S batteries. Herein, we systematically explore the impact of sulfur species adsorption energy on the electrocatalytic activity in Li–S batteries by modulating the metal d -band structure of Pt 3 M (M = Cu, Fe, Ti, Co) alloy model systems. The Pt 3 Co catalyst, possessing a balanced d -band center, exhibited the highest redox kinetics and Li–S cell performance due to its lowest energy barrier for the rate-determining step in the sulfur reduction reaction. Furthermore, the adsorption energies of sulfur (S) and lithium (Li) single atoms can offer deeper insights into the electrocatalytic activity in Li–S electrochemistry, indicating their great potential as descriptors to develop advanced electrocatalysts. The volcano-type correlation of the d -band center and descriptor with the kinetics of the sulfur reduction reaction highlighted that moderate adsorption of Li and S on the catalyst surface with a balanced d -band center is the key to achieving optimal Li–S battery performance. This work emphasizes the importance of tailoring the surface properties and electronic structures of the electrocatalyst according to the intrinsic characteristics of electrocatalysts.