Synergistic Oxygen Defect Engineering and Neodymium-Ion Intercalation Endows MIL-88B(V)-Derived V<sub>2</sub>O<sub>5</sub> with Fast Diffusion Kinetics and Enhanced Cycling Stability for Aqueous Zinc-Ion Batteries
Yibo Zhang, Zhihua Li, Bo Zhao, Dongming Xu, Ziteng Guo, Jingwei Zhang, Chunhong Gong
Abstract
Vanadium-based oxides with unique layered structures and multiple oxidation states have attracted considerable attention for aqueous zinc-ion batteries (AZIBs). However, the inferior conductivity and nearly nonporous structural characteristics of commercial V 2 O 5 inevitably hinder the transport of electrons/ions, and the inherently narrow interlayer spacing and strong electrostatic interactions severely restrict the further development of V 2 O 5 cathodes. In this work, neodymium (Nd) ions were employed as guests to intercalate into MIL-88B(V)-derived V 2 O 5 (denoted as O V -NVO) by a one-step hydrothermal process and as stable cathode materials for AZIBs. Benefiting from its well-designed honeycomb-like porous structure, large surface area, expanded interlayer spacing, abundant oxygen vacancies, and feeble electrostatic interactions, the O V -NVO cathode delivered a prominent discharge capacity of 455.2 mAh g –1 at 0.1 A g –1 and exhibited satisfactory rate capability (341.5 mAh g –1 at 5.0 A g –1 ) and cycling stability (90.8% capacity retention after 2000 cycles at 5.0 A g –1 ). Impressively, the assembled Zn//O V -NVO flexible battery can operate stably under extreme bending conditions and exhibits superior electrochemical behavior. Furthermore, the reversible Zn 2+ storage mechanism and structural evolution of the O V -NVO cathode were further analyzed by kinetic analysis, ex situ characterizations, and density functional theory calculations. This synergistic strategy by combining Nd-ion intercalation and oxygen defect engineering provides an effective approach to the design of high-performance vanadium-based cathode materials, offering more possibilities for the practical applications of AZIBs.