Spatial-Confinement in Biomimetic Catalysts: Enhancing Homolytic Sulfur-Chain Reactions and Enzyme-like Activity for High-Performance Lithium-Sulfur Batteries

Abstract

The most burning issue for high-energy-density lithium-sulfur batteries is developing high-efficient catalyst to address sulfur reaction kinetics and lithium polysulfide shuttling effects. In this work, we present Fe-TCPP@Cu-BTC, a biomimetic catalyst that mimics cytochrome c oxidase, by encapsulating porphyrin-based small molecules into metal-organic frameworks, for high-performance lithium-sulfur batteries. Through a series of in-situ spectroscopic analyses and theoretical simulations, it was found that the Cu-Fe bimetallic center within the spatially confined Fe-TCPP@Cu-BTC significantly promotes the homolytic cleavage of Li₂S₆ to LiS₃, and accelerates their subsequent conversion to Li₂S. The enzyme-like properties were further evaluated using Michaelis-Menten kinetics, confirming that the homolytic reaction can increase the sulfur conversion rate by nearly 100-fold. As a result, the pouch lithium-sulfur batteries delivered an energy density exceeding 300 Wh/kg. This work demonstrates the tremendous potential of component and structural regulation of biomimetic enzymes in the conversion reactions of metal-sulfur batteries.