Synergizing catalytic activity and electronic structure adjustment by dual-atomic sites for high-performance lithium–sulfur batteries

Abstract

The slow redox kinetics of lithium polysulfides (LiPSs) and the high energy barrier for Li₂S deposition/dissociation are considered two significant challenges impeding the implementation of lithium–sulfur (Li–S) batteries. In this study, we have screened and successfully synthesized Fe-Cu and Co-Cu dual-atomic catalytic materials supported on reduced graphene oxide (rGO), which exhibits synergistic catalytic activity towards LiPSs and facilitates the adjustment of the electronic structure of Li₂S. Consequently, the sulfur cathode with Fe-Cu dual-atomic catalyst sites exhibits remarkable electrochemical performance, including a high initial capacity of 1164 mAh g⁻¹ at 0.2 C, an exceptional rate capacity of 625.2 mAh g⁻¹ at 5 C, and excellent cycle stability with a low capacity fading rate of 0.045 % per cycle over 500 cycles at 1 C. Notably, even with a high sulfur loading (8.5 mg cm⁻²) and a low E/S ratio (6 μL mg⁻¹), an impressive initial capacity of 7.33 mAh cm⁻² is achieved. Furthermore, the Li–S pouch cell demonstrates a high discharge capacity of 5.5 mAh cm⁻² at 0.2 C, along with a capacity retention of 82 % after 100 cycles. These results highlight the importance of elemental choice and synergy of dual-atomic catalytic materials in substantially propelling the sulfur redox kinetics in Li–S batteries.