•All-solid-state complementary ITO/WO3/Ta2O5/NiO/ITO ECD.•UV curing LiClO4+PC+UV as a solid electrolyte.•NiO is an auxiliary layer for a complementary ECD.•ECD deposited by ion-beam assisted electron-beam evaporation This research investigates the optical, nanostructure, electrochemical, and binding-energy performances of a Nickel Oxide (NiO) auxiliary layer for a complementary ultraviolet (UV)-cured all-solid-state electrochromic device (ECD). The complementary ITO/WO3/Ta2O5/Electrolyte/NiO/ITO ECD was separated into two sub-modules, one being the colored NiO anode, the other being the colored WO3 cathode. These were combined using UV curing LiClO4+PC+UV glue as a solid electrolyte. The NiO film was deposited by ion-beam assisted (IAD) electron-beam evaporation under different oxygen flow rates ranging from 5 to 20 sccm, and the evaporation formed columnar nanostructures that allowed the Li+ ions to enter and leave. These experimental results exhibited location shifts for the binding-energy of Ni3d and O1s has the blue shift at the oxygen flow far away of 15 sccm. Depositing the NiO film under an oxygen flow of 15 sccm (111) showed the highest color/bleach variation of ΔT=45.9%@550nm, the greatest cyclic voltammetry (CV) cladding area of Q=31.39 mC, an alternating current (AC) impedance of 28 kΩ, and an ionic conduction rate of 4.46×10−7 S cm−1. The columnar NiO film deposited using IAD electron-beam evaporation has the potential to be used as an auxiliary layer for an all-solid-state ECD. Display omitted