Mechanistic Insights into the Coloration, Evolution, and Degradation of NiO Electrochromic Anodes.

NiO is recognized as the leading candidate for smart window anodes that can dynamically modulate optical absorption, thereby achieving energy efficiency in construction buildings. However, the electrochromic mechanism in NiO is not yet clear, and the ionic species involved are sometimes ambiguous, particularly in aprotic electrolytes. We demonstrate herein that the "net coloration effect" originates from newly generated high-valence Ni/Ni ions during anion-dependent anodization, and the Li intercalation/deintercalation only plays a role in modulating the oxidation state of Ni.

Life-cycling and uncovering cation-trapping evidence of a monolithic inorganic electrochromic device: glass/ITO/WO/LiTaO/NiO/ITO.

The visualization of the microstructure change and of the depth of lithium transport inside a monolithic ElectroChromic Device (ECD) is realized using an innovative combined approach of Focused Ion Beam (FIB), Secondary Ion Mass Spectrometry (SIMS) and Glow Discharge Optical Emission Spectroscopy (GDOES). The electrochemical and optical properties of the all-thin-film inorganic ECD glass/ITO/WO3/LiTaO3/NiO/ITO, deposited by magnetron sputtering, are measured by cycling voltammetry and in situ transmittance analysis up to 11 270 cycles. A significant degradation corresponding to a decrease in the capacity of 71% after 2500 cycles and of 94% after 11 270 cycles is reported.