Electrochromic nickel oxide films and their compatibility with potassium hydroxide and lithium perchlorate in propylene carbonate: Optical, electrochemical and stress-related properties

Abstract

Electrochromic nickel oxide films and their compatibility with potassium hydroxide and lithium perchlorate in propylene carbonate: Optical, electrochemical and stress-related properties. AbstractPorous thin films of Ir oxide were prepared by reactive dc magnetron sputtering onto unheated substrates. The crystallite size was ~5 nm, and a small amount of unoxidized Ir was present. The electrochromic performance was studied by optical transmittance measurements and cyclic voltammetry applied to films in aqueous and non-aqueous electrolytes, specifically being 1M propionic acid, 1M potassium hydroxide (KOH), and 1M lithium perchlorate in propylene carbonate (Li-PC). Cyclic voltammetry measurements indicated that the films had a fractal surface structure. Good electrochromism, with mid-luminous transmittance modulation between ~55 and ~90 % in ~100-nm-thick films, was documented in all of the electrolytes.

Anodic Electrochromism for Energy‐Efficient Windows: Cation/Anion‐Based Surface Processes and Effects of Crystal Facets in Nickel Oxide Thin Films

“…The RBS spectra were fitted to a model for the film-substrate system by use of the SIMNRA program [61] . [30,31,62] .…”

“…The electrochromism of lithium-containing Ni oxide films has been investigated in numerous studies aimed at elucidating basic optical and electrochemical mechanisms [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] as well as to produce counter electrodes for application in W-oxide-based EC devices [5,27,32,[34][35][36][37][38] .…”

Strongly Improved Electrochemical Cycling Durability by Adding Iridium to Electrochromic Nickel Oxide Films

“…[1][2][3] These devices normally utilize joint transport of small ions and electrons between a thin film of tungsten oxide and a counter electrode based on nickel oxide, basically in the same way as in an electrical battery, and the optical transmittance is low when the charge resides in W oxide while the transmittance is high when the charge is in Ni oxide. Ni oxide films suffer from optical degradation and limitation in modulation span under extended electrochemical cycling, [4][5][6] and several recent studies aimed at alleviating these deficiencies have been reported. Beneficial effects of additives to the Ni oxide have been studied, specifically for Li, 7,8 C, 9,10 N, 11 W, 12 (Li,W), 13 (Li,Al), 14 (Li,Zr), 15 and several more.…”

Improved Electrochemical Cycling Durability in a Nickel Oxide Double‐Layered Film

“…For example, the degradation of NiO x film tested in KOH electrolyte was already reported after about 1000 cycles, whereas the use of anhydrous lithium perchlorate dissolved in propylene carbonate lengthened the cycling life of this film . However, on the contrary, it was reported that it was possible to reach a value of 10 000 cycles for NiO x film in KOH electrolyte, whereas the use of lithium conducting anhydrous electrolyte yielded very rapid cycling degradation . This problem deserves further investigation.…”

“…Coloration/bleaching cycles are accompanied by mechanical stresses arising owing to insertion/extraction of ions, such as compressed and tensile stresses reported in ref. . These stresses may destroy the EC film, causing grain fracture and total damage to an EC material.…”