Research on High-Durability Siloxane-Coated Vanadium Pentoxide Cathodes for Aqueous Zinc-Ion Batteries

Abstract

Aqueous zinc-ion batteries (AZIBs) are promising for large-scale storage due to low cost, inherent safety, and long cycle life. Among AZIB cathodes, hydrated vanadium pentoxide (VOH) cathode combines high theoretical capacity with a hydrated layered framework that provides open Zn2+ diffusion pathways and elastic accommodation. However, the application of VOH in AZIB remains hindered by issues such as vanadium dissolution, albeit slow and small, leading to capacity fade. This work introduces a self-assembly monolayer (SAM) of methyltri-n-butoxysilane (MTBOS) through an atomic layer of silicon oxide covalently anchored on the surface of VOH that shields vanadium cations from leaching by aqueous electrolyte, enabling ultralong cycle life, retaining excellent storage capacity and reaction and transport kinetics. The methyl ligand anchored to atomic layer of silica through covalent bond C-Si and Si–O–Si cross-linked silica layer attached to VOH through Si–O–V bonds. The SAM of MTBOS passivates the interface and enhances the structural integrity of VOH, while remains ion-permissive. The VOH with SAM (SVOH) yields fast Zn2+ kinetics and remarkable longevity, achieving ~89% capacity retention after 6000 cycles at a current density of 5 A g−1.