A facile electrochemical lithiation method to prepare porous nickel oxide electrodes with high electrochromic performance

Abstract

A facile electrochemical lithiation method was developed in the framework of the wet chemical route, and NiO films with various lithium contents have been successfully prepared. The structure and electrochromic properties were characterized using SEM, HRTEM, XRD, XPS, etc. The results indicate that all NiO films show a porous morphology, and the ratio of Ni3+/Ni2+ increases from 1.12 to 1.46 after electrochemical lithiation. The storage capacity in lithium electrolytes, effective ionic diffusion rate, transmittance modulation, and coloring efficiency are effectively improved. The optimized NiO electrode exhibits an excellent storage capacity of 6.4 mC/cm2 and transmittance modulation at 550 nm of 35.7%, compared to the pristine NiO (Q = 4.4 mC/cm2, ΔT = 24.3%). Two electrochromic devices were respectively assembled with the pristine and lithiated NiO electrodes as the anodic electrochromic layer. The latter exhibits higher transmittance modulation and coloring efficiency, proving that the electrochemical lithiation method is an effective way to prepare high-performance electrochromic devices.