Customizing Hydrophilic Terminations for V2CTx MXene Toward Superior Hybrid‐Ion Storage in Aqueous Zinc Batteries

Abstract

AbstractV2CTx MXene is a “rising star” cathode material for aqueous zinc‐based batteries (AZBs) owing to its large/flexible interlayer spacing, rich redox chemistry of V, and high electronic conductivity. Nevertheless, the plentiful F surface terminations generated during the common preparation (fluorine‐containing acid etching process) of V2CTx generally result in high hydrophobicity, poor Zn affinity, and sluggish ion‐diffusion kinetics. Herein, a novel OH‐termination‐rich V2CTx material with interlayer “K+‐pillars” (alk‐V2CTx) is fabricated via a facile one‐step alkalization method, which features excellent hydrophilicity, expanded ion‐transport channels, and robust layered structure. Impressively, the tailored alk‐V2CTx cathode enables highly reversible and rapid Li+/Zn2+ co‐insertion/extraction electrochemistry in the formulated 15 m LiTSFI + 1 m Zn(CF3SO3)2 aqueous electrolyte, meanwhile, the “self‐exfoliation” phenomenon of MXenes upon cycling significantly increases the active sites, rendering the superior rate performance (498.2/195.1 mAh g−1 at 0.1/30 A g−1, respectively) and exceptional cycling life (96.2% capacity retention over 20 000 cycles). Systematic in situ/ex situ analyses and theoretical computations elucidate the above hybrid‐ion storage mechanisms. Finally, flexible quasi‐solid‐state rechargeable Zn batteries employing the alk‐V2CTx cathode exhibit inspiring energy output even under severe deformation conditions and low temperatures. This study provides new perspectives for designing high‐performance MXene‐based cathodes for AZBs by modulating surface terminations.