Dynamic Stereo‐Conformation of Catalyst‐In‐Cavity Biomimetic Enzymes Enable High‐Sulfur‐Utilization and Lean‐Electrolyte Lithium‐Sulfur Batteries

Abstract

AbstractThe key challenges for pursuing high‐energy‐density lithium‐sulfur (Li‐S) batteries lie in struggling sulfur conversions under high‐sulfur‐loading and low electrolyte‐to‐sulfur (E/S) ratio conditions. To mimic high‐efficient natural enzymes, in this work, sulfonated cobalt phthalocyanine (CoPC) is implanted in β‐cyclodextrin (β–CD) cavity for preparing β–CD@CoPC biomimetic catalysts, which enables a good electrochemical contact with solvated lithium polysulfides in a locally enriched electrolyte. Moreover, the dynamic stereo‐conformation evolution of CoPC in hydrophobic β–CD cavity promotes subsequent sulfur redox kinetics and induces the separation of Li2S from the catalyst, further improving catalysis efficiency. The catalytic activity is quantified through specific Michaelis–Menten equations for enzymatic reactions and it showed that β–CD@CoPC improved catalytic ability by 3 and 30 times compared to that of the β–CD and CoPC catalysts, respectively. As a result, the Li–S pouch cell with mere 1.0 wt% β–CD@CoPC exhibits a high initial areal capacity of 11.6 mAh cm−2 under high‐sulfur‐loading (12.8 mg cm−2) and low E/S ratio (3.5 µL mg−1). This strategy provides a feasible way to tackle sulfur conversion issues under lean electrolytes for next‐generation high‐energy batteries.