ChemInform Abstract: Degradation of Electrochromic Amorphous WO3 Film in Lithium‐Salt Electrolyte.

Hashimoto, Satoshi; Matsuoka, Hiroaki; Kagechika, Hiroshi; Susa, Masahiro; Gotō, Kazuhiro

doi:10.1002/chin.199025009

Cited by 3 publications

(6 citation statements)

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“…According to Hashimoto et al, the cause of degradation in WO x electrochromic devices is a result of Li + accumulation at the initial stage of coloring and bleaching cycles. 7 Similar ion-trapping models were also proposed to explain the degradation of WO x thin films. 8,9 To study the electrochromic performance and understand the degradation behavior of the alkali-metal-intercalated WO x compounds, the fundamental insertion parameters of the alkali metal ions such as the diffusion coefficient need to be investigated to establish links with the detailed kinetic behavior of the intercalation compounds, 10 because the processing parameters have a strong influence on the crystalline structures of the compounds.…”

Section: Introductionmentioning

confidence: 88%

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WO_x) Thin Films

et al. 2017

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This research aims to understand the fundamental aspects of annealing on the electrochromic performance of tungsten oxides, using as-synthesized W18O49 substoichiometric bundled nanowires benchmarked against commercial WO3 nanoparticles. Linking detailed structural analyses with the electrochromic measurement results, we have investigated the electrochromic performance effects of low temperature annealing, up to 350 °C, on tungsten oxide (WO x ) thin films, trying to establish the fundamental heat treatment–structure–performance loop. We have found that the annealing treatment at low temperature improved the optical modulation and long-term durability of the WO x thin films, without changing the structure and morphology of the as-synthesized samples. The 350 °C annealing was found to have the best stability improvement for the WO3 nanoparticle films during the electrochromic assessments, with a 4% improvement for Li+ intercalation and a 12% improvement for deintercalation, compared with the untreated WO3 samples. Further improvements have been achieved for the W18O49 nanowire thin films, with a stability improvement of 36% for Li+ intercalation and 60% for deintercalation against the as-prepared W18O49 nanowire samples during the electrochromic performance testing.

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Section: Introductionmentioning

confidence: 88%

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WO_x) Thin Films

et al. 2017

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“…6 Moreover, the lifetime of an amorphous W0,-TiO, film was found to exceed that of a WO, film. ' In this paper we attempt to clarify the mechanism of the prolonged lifetime of amorphous W0,-TiO, films.…”

Section: Introductionmentioning

confidence: 99%

“…The stored lithium during one colouring and bleaching cycle accumulates after a large number of cycles as clarified in Ref. 6.…”

Section: Introductionmentioning

confidence: 99%

Prolonged lifetime of electrochromism of amorphous WO₃–TiO₂ thin films

Hashimoto

Matsuoka

1992

Surface & Interface Analysis

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The lifetime of the electrochromism of the W0,-TiO, films prepared by vacuum evaporation is found to exceed that of WO, films by a factor of five. X-ray difiactioo has revealed that the crystal structure of W0,-TiO, films stays amorphous, while crystalline compounds are formed in amorphous WO, films after colouring and bleaching. W0,-TiO, films stay amorphous after they are annealed at 40O0C, although WO, films crystallize. SIMS and XPS analyses have revealed that half the amount of lithium injected during a colouring cycle is stored as 0-Li bonds in the bleached film. In W0,-TiO, films the number of bonds such as W-OH and W=O in which lithium ions accumulate is reduced. We conclude that the lifetime of the electrochromism is prolonged for amorphous W0,-TiO, films, because lithium does not accumulate and the W0,-TIO, films stay amorphous.

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“…The physical and chemical bases of the irreversibility remain poorly known, experimentally as well as theoretically. Moreover, a number of Li-based compounds may form at low potentials at interfaces or in the host material 11-13 .…”

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confidence: 99%

“…Hence they “share” their bonds with a number of oxygens, which is believed to lead to much weaker bonds than the ionic ones in Li 2 O and Li 2 O 2 aggregates. It should also be noted that Li tungstates have been observed 13 in degraded amorphous WO 3 films, and it has been argued 22 that these compounds are formed at voltages below 2 V vs . Li + .…”

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confidence: 99%

Eliminating degradation and uncovering ion-trapping dynamics in electrochromic WO3 thin films

2015

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Amorphous WO3 thin films are of keen interest as cathodic electrodes in transmittance-modulating electrochromic devices. However, these films suffer from ion-trapping-induced degradation of optical modulation and reversibility upon extended Li+-ion exchange. Here, we demonstrate that ion-trapping-induced degradation, which is commonly believed to be irreversible, can be successfully eliminated by constant-current-driven de-trapping, i.e., WO3 films can be rejuvenated and regain their initial highly reversible electrochromic performance. Pronounced ion-trapping occurs when x exceeds ~0.65 in LixWO3 during ion insertion. We find two main kinds of Li+-ion trapping sites (intermediate and deep) in WO3, where the intermediate ones are most prevalent. Li+-ions can be completely removed from intermediate traps but are irreversibly bound in deep traps. Our results provide a general framework for developing and designing superior electrochromic materials and devices.

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ChemInform Abstract: Degradation of Electrochromic Amorphous WO3 Film in Lithium‐Salt Electrolyte.

Cited by 3 publications

References 1 publication

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WO_x) Thin Films

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WO_x) Thin Films

Prolonged lifetime of electrochromism of amorphous WO₃–TiO₂ thin films

Eliminating degradation and uncovering ion-trapping dynamics in electrochromic WO3 thin films

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ChemInform Abstract: Degradation of Electrochromic Amorphous WO3 Film in Lithium‐Salt Electrolyte.

Cited by 3 publications

References 1 publication

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WOx) Thin Films

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WOx) Thin Films

Prolonged lifetime of electrochromism of amorphous WO3–TiO2 thin films

Eliminating degradation and uncovering ion-trapping dynamics in electrochromic WO3 thin films

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Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WO_x) Thin Films

Low Temperature Annealing Improves the Electrochromic and Degradation Behavior of Tungsten Oxide (WO_x) Thin Films

Prolonged lifetime of electrochromism of amorphous WO₃–TiO₂ thin films