Enhanced Electron Delocalization within Coherent Nano-Heterocrystal Ensembles for Optimizing Polysulfide Conversion in High-Energy-Density Li-S Batteries.

Abstract

Commercialization of high energy density Lithium-Sulfur (Li-S) batteries is impeded by challenges such as polysulfide shuttling, sluggish reaction kinetics, and limited Li⁺ transport. Herein, a jigsaw-inspired catalyst design strategy that involves in situ assembly of coherent nano-heterocrystal ensembles (CNEs) to stabilize high-activity crystal facets, enhance electron delocalization, and reduce associated energy barriers is proposed. On the catalyst surface, the stabilized high-activity facets induce polysulfide aggregation. Simultaneously, the surrounded surface facets with enhanced activity promote Li₂S deposition and Li⁺ diffusion, synergistically facilitating continuous and efficient sulfur redox. Experimental and DFT computations results reveal that the dual-component hetero-facet design alters the coordination of Nb atoms, enabling the redistribution of 3D orbital electrons at the Nb center and promoting d-p hybridization with sulfur. The CNE, based on energy level gradient and lattice matching, endows maximum electron transfer to catalysts and establishes smooth pathways for ion diffusion. Encouragingly, the NbN-NbC-based pouch battery delivers a Weight energy density of 357 Wh kg^-1, thereby demonstrating the practical application value of CNEs. This work unveils a novel paradigm for designing high-performance catalysts, which has the potential to shape future research on electrocatalysts for energy storage applications.