Electrostatic and Structural Engineering in Preintercalated V₂O₅: A Design Framework for Multivalent Ion Storage

Preintercalation has emerged as a powerful strategy to modulate the electrochemical performance of layered vanadium oxides, yet a unified mechanistic understanding linking structural and electrostatic effects remains lacking. Here, we establish a unified framework describing how preintercalated species govern ion transport, structural stability, and electrochemical behavior in V₂O₅-based cathodes. We show that preintercalation operates through a coupled structural-electrostatic mechanism governed by interlayer spacing, charge screening, and solvation effects, where guest species act as interlayer pillars that stabilize the lattice while simultaneously tuning the local electrostatic potential landscape and charge screening environment. The interplay between ionic size, charge density, hydration state, and electronic structure defines Zn²⁺ diffusion barriers, redox kinetics, and electrochemical reversibility. By systematically analyzing monovalent, divalent, and trivalent preintercalated metal ions, we identify key design principles that dictate optimal interlayer spacing, electronic conductivity, and ion mobility. Importantly, the role of structural water is redefined as an active electrostatic mediator reducing effective ion charge and lowering migration barriers. This work transcends conventional material-specific discussions and provides a generalizable design framework for preintercalation engineering in layered oxides, with implications extending beyond zinc-ion systems to multivalent and hybrid energy storage technologies.