Disentangling Li Diffusion Characteristics in Amorphous Nickel Oxide

The advancement of electrochromic devices, including smart windows, is important for improving energy efficiency in modern society. Nickel oxide thin films are key functional materials in this technology and have attracted significant attention due to their electrochemical activity and optical properties. However, existing theoretical studies have primarily focused on crystalline NiO, while systematic understanding of Li⁺ diffusion mechanisms in amorphous NiO remains limited. In this work, first-principles calculations combined with second-generation Car-Parrinello molecular dynamics simulations and the melt-quenching method are employed to construct amorphous NiO models with varying oxygen content, enabling investigation of oxygen-dependent Li⁺ diffusion behavior. The results show that the Li⁺ diffusion coefficient increases with increasing oxygen content, accompanied by a reduction in diffusion barriers. Analysis of local structural environments further reveals that Li coordination with under-coordinated Ni-O polyhedra plays a key role in facilitating ion migration, providing atomistic insight into the observed diffusion trends. This study establishes a structure-diffusion relationship in amorphous NiO and provides atomistic understanding of how oxygen stoichiometry modulates Li⁺ transport behavior in electrochromic materials.