Polyoxovanadate-Based Supramolecular Vesicles for Enhancing Lithium-Sulfur Battery Performance under High Rates, High Loadings, and Subzero-Temperature Conditions

Abstract

The practical application of Li-S batteries has long been hindered by the polysulfide shuttle effect and sluggish redox kinetics. In this study, a polyoxovanadate-based supramolecular vesicle (V34-DODA) is designed, which is self-assembled from K10[V34O82]•20H2O (V34) and dioctadecyldimethylammonium bromide (DODA) driven by the synergy of electrostatic interactions and solvent polarity. The presence of a vesicle-like architecture suppresses the aggregation of V34, thereby facilitating the uniform distribution of catalytically active sites. DODA demonstrates moderate affinity for Li2Sx species, primarily driven by extended-range electrostatic forces. Such long-distance electrostatic attraction promotes swift accumulation of polysulfides from the electrolyte near the catalyst surface, thereby enhancing their transport to the V34 active centers. Whereafter, polysulfides undergo robust chemical immobilization and subsequent reversible catalytic transformation mediated by V34. These two components form a "electrostatic trapping-chemical anchoring" synergistic effect in terms of adsorption behavior, which jointly improves the kinetic efficiency of the polysulfide conversion reaction.Therefore, Li-S batteries assembled with V34-DODA functional separator exhibit outstanding cycling performance. After 2000 cycles at current densities of 3 C, reversible specific capacities of 480.8 mAh g -1 can be retained, with capacity fading rates of 0.025% per cycle. It also demonstrates excellent performance under the conditions of high sulfur loading (~6.6 mg cm -2 ) and low temperature (-20 °C). This study clarifies the electrochemical reaction process of functional materials based on polyoxovanadate supramolecular assemblies in Li-S batteries, providing a novel material design strategy to address key challenges such as polysulfide shuttling and sluggish conversion kinetics.