Theoretical investigation on the dendrite suppression and desolvation promotion effect of coating material on Zn metal anode for aqueous zinc-ion batteries: case study of oxide coating

Abstract

Interfacial engineering via oxide coatings offers a promising strategy to improve the electrochemical performance and cycling stability of aqueous zinc-ion batteries (AZIBs). Here, we develop a multiscale theoretical framework combining ab initio density functional theory (DFT) and classical molecular dynamics (MD) simulations to systematically investigate the effects of representative oxide coatings—α-SiO₂, α-Al₂O₃, α-TiO₂, α-ZnO, α-Fe₂O₃, and α-CoO—across multiple crystallographic facets on Zn surface chemistry, ion transport behavior, and Zn²⁺ desolvation dynamics. DFT calculations reveal that the TiO₂ [110] surface exhibits ultralow Zn diffusion barriers on the order of hundreds of millielectron volts, in sharp contrast to the substantially higher barriers on Al₂O₃ and CoO (a few electron volts) and on ZnO and SiO₂ (exceeding ten electron volts), indicating excellent ion mobility and potential for dendrite suppression. Complementary MD simulations demonstrate that Zn²⁺ desolvation is strongly modulated by oxide surface chemistry, temperature, and external electric fields. In the absence of an electric field, the SiO₂ [001] surface induces an exceptionally high desolvation ratio of ~81% at room temperature, far exceeding that of the bare Zn surface (~20%) and the moderate desolvation ratios (~40%) observed on CoO [101], ZnO [011], TiO₂ [111], and Fe₂O₃ [101]. These results identify SiO₂ as a superior coating material—consistent with experimental observations—for stabilizing Zn anodes through its ultrahigh desolvation capability. In contrast, TiO₂, Al₂O₃, and CoO offer a balanced combination of moderate desolvation efficiency and low Zn diffusion barriers, supporting fast ion transport and high-rate capability. Overall, this work establishes a predictive framework for the rational design of oxide-based interfacial layers, providing mechanistic insights to guide the development of durable and high-performance AZIB systems.