Polyoxometalate-cyclodextrin-based Cluster-Organic Supramolecular Framework for Polysulfide Conversion and Guest-host Recognition in Lithium-sulfur Batteries.

Abstract

Developing polyoxometalate-cyclodextrin cluster-organic supramolecular framework (POM-CD-COSF) still remains challenging due to an extremely difficult task in rationally interconnecting two dissimilar building blocks. Here we report an unprecedented POM-CD-based framework crystalline structure produced through the self-assembly process of a Krebs-type polyoxometalate, [Zn2(WO2)2(SbW9O33)2]10-, and two β-cyclodextrin units (β-CD). For the first time, we present the exploration of new application forms of POM-CD-COSF materials in Lithium-sulfur (Li-S) batteries. The as-prepared POM-CD-COSF-based battery separator can be applied as a lightweight barrier (approximately 0.3 mg cm-2) to mitigate the fundamental polysulfide shuttle effect in Lithium-sulfur chemistry. The designed Li-S batteries equipped with the POM-CD-COSF modified separator exhibit remarkable electrochemical performance, attributed to fast Li+ diffusion through the supramolecular channel of β-CD, efficient polysulfide-capture ability by the dynamic host-guest interaction of β-CD, and improved sulfur redox kinetics by the bidirectional catalysis of POM cluster. This research provides a broad perspective for the development of multifunctional supramolecular POM frameworks and their applications in Li-S batteries.