Achieving Synergetic Anion-Cation Redox Chemistry in Freestanding Amorphous Vanadium Oxysulfide Cathodes toward Ultrafast and Stable Aqueous Zinc-Ion Batteries

摘要

Flexible aqueous zinc-ion batteries (AZIBs) with high safety and low costhold great promise for potential applications in wearable electronics, but thestrong electrostatic interaction between Zn~(2+) and crystalline structures, andthe traditional cathodes with single cationic redox center remain stumblingblocks to developing high-performance AZIBs. Herein, freestanding amorphousvanadium oxysulfide (AVSO) cathodes with abundant defects and auxiliaryanionic redox centers are developed via in situ anodic oxidation strategy.The well-designed amorphous AVSO cathodes demonstrate numerous Zn~(2+)isotropic pathways and rapid reaction kinetics, performing a high reversiblecapacity of 538.7 mAhg~(?1) and high-rate capability (237.8 mAhg~(?1)@40Ag~(?1)).Experimental results and theoretical simulations reveal that vanadiumcations serve as the main redox centers while sulfur anions in AVSO cathodeas the supporting redox centers to compensate local electron-transfer abilityof active sites. Significantly, the amorphous structure with sulfur chemistrycan tolerate volumetric change upon Zn~(2+)/H+ insertion and weaken electrostaticinteraction between Zn~(2+) and host materials. Consequently, the AVSOcomposites display alleviated structural degradation and exceptional longtermcyclability (89.8% retention after 20 000 cycles at 40 Ag~(?1)). This work canbe generally extended to various freestanding amorphous cathode materialsof multiple redox reactions, inspiring development of designing ultrafast andlong-life wearable AZIBs.