A Zn8 Double‐Cavity Metallacalix[8]arene as Molecular Sieve to Realize Self‐Cleaning Intramolecular Tandem Transformation of Li−S Chemistry

Toward the well-explored lithium-sulfur (Li-S) catalytic chemistry, the slow adsorption-migration-conversion kinetics of lithium polysulfides on catalytic materials and Li2S deposition-induced passivation of active sites limit the rapid and complete conversion of sulfur. Conceptively, molecular architectures can provide atom-precise models to understand the underlying active sites responsible for selective adsorption and conversion of LiPSs and Li2S2/Li2S species. Here, an octanuclear Zn(II) (Zn-8) cluster is presented, which features a metallacalix[8]arene with double cavities up and down the Zn-8 ring. The central Zn-8 ring and the specific double cavities with organic ligands of different electronegativity and bonding environments render active sites with variable steric hindrance and interaction toward the sulfur-borne species. An intramolecular tandem transformation mechanism is realized exclusively by Zn-8 cluster, which promotes the self-cleaning of active sites and continuous electrochemical reaction. Notably, the external azo groups and internal Zn/O sites of Zn-8 cluster in sequence stimulate the adsorption and conversion of long chain Li2Sx (x >= 4) and short chain Li2S/Li2S2, contributing to remarkable rate performance and cycling stability. This work pioneers the application of metallacalix[n]arene clusters with atom-precise structure in Li-S batteries, and the proposed mechanism advances the molecule-level understanding of Li-S catalytic chemistry.