Engineering a deficient-coordinated single-atom indium electrocatalyst for fast redox conversion in practical 500 W h kg−1-level pouch lithium–sulfur batteries

Abstract

Single-atom catalysts (SACs) with unique coordination chemistry open promising opportunities as a high-efficiency electrocatalyst system in lithium–sulfur (Li–S) batteries, and the rational design has been highlighted for lithium polysulfides (LiPSs) conversion kinetics. Herein, we assemble indium SACs attached to carbon nanotubes via porphyrins (SAIn@CNT), which can overcome the mismatch and agglomeration challenges in the spatial scale during the pyrolysis process. Moreover, an unsaturated coordination center configuration is obtained, which can be exploited for the handling of the electrocatalytic selectivity and activity. Both theoretical and experimental methods confirm that the In–N3 coordination structure exhibit higher polysulfide affinity and electrocatalytic activity than common In–N4 centers due to the stronger hybridization between the In 4d and S 3p orbitals. Thus, SAIn@CNT with In–N3 coordination exhibits significant improvement in rate and cycling performance in the coin cell. Furthermore, the SAIn@CNT pouch cell with high sulfur content (14.29 g) displays a significant specific energy of 495 W h kg⁻¹ and stable cycling performance of 50 cycles at 0.2 C, which is the first reported all over the world. Consequently, this study develops an intensive vision into the basic understanding of the catalysis properties for practical Li–S batteries with high energy density and long-term cycling.