{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T05:19:32Z","timestamp":1788153572431,"version":"build-2803163510"},"reference-count":43,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2026,8,29]],"date-time":"2026-08-29T00:00:00Z","timestamp":1787961600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100011789","name":"Jilin Province Science and Technology Department","doi-asserted-by":"crossref","award":["20240404047ZP"],"award-info":[{"award-number":["20240404047ZP"]}],"id":[{"id":"10.13039\/501100011789","id-type":"DOI","asserted-by":"crossref"}]},{"award":["20240404047ZP"],"award-info":[{"award-number":["20240404047ZP"]}],"id":[{"id":"https:\/\/ror.org\/049x38272","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Micromachines"],"abstract":"<jats:p>Electrochromic tungsten oxide (WO3) films suffer from gradual performance degradation during repeated ion insertion\/extraction processes, while the relationship between electrolyte-dependent ion accommodation and structural stability remains insufficiently understood. Herein, magnetron-sputtered WO3 thin films were systematically investigated in H2SO4, LiClO4, ZnSO4, and Al2(SO4)3 electrolytes to clarify the coupling relationship among ion accommodation, electronic structure evolution, microstructural retention, and electrochromic durability. Combined electrochemical measurements with UV\u2013visible spectroscopy, atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and reflected electron energy loss spectroscopy (REELS) reveal that electrolyte chemistry regulates the balance between electrochemical activation and structural tolerance. Highly mobile H+ and strongly interacting Al3+ ions promote rapid ion transport and enhanced W6+ reduction but may induce excessive structural perturbation, defect accumulation, and accelerated degradation during cycling. Zn2+ exhibits intermediate behavior, whereas Li+ enables balanced ion accommodation through reversible W6+\/W5+ conversion while preserving the WO3 framework. Consequently, the LiClO4 electrolyte achieves superior electrochromic performance with an optical modulation of 80.97% and improved cycling stability. These results demonstrate that durable electrochromic behavior is governed not by maximizing ion transport or reduction degree, but by achieving a reversible ion accommodation regime compatible with the structural tolerance of the host framework. This work provides a microstructure-oriented strategy for designing stable WO3-based electrochromic devices through electrolyte regulation.<\/jats:p>","DOI":"10.3390\/mi17091033","type":"journal-article","created":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T02:08:58Z","timestamp":1788142138000},"page":"1033","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Electrolyte-Regulated Ion Accommodation and Microstructural Stability in WO3 Electrochromic Thin Films"],"prefix":"10.3390","volume":"17","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1472-8185","authenticated-orcid":false,"given":"Xuefeng","family":"Chu","sequence":"first","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"}]},{"given":"Siming","family":"Qiao","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"investigation","vocabulary":"credit"},{"role":"data-curation","vocabulary":"credit"}]},{"given":"Wenhao","family":"Ma","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"software","vocabulary":"credit"}]},{"given":"Kunjie","family":"Lin","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"software","vocabulary":"credit"}]},{"given":"Faxin","family":"Peng","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Xinyuan","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"software","vocabulary":"credit"}]},{"given":"Jie","family":"Wu","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]},{"given":"Haiyang","family":"Zhao","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]},{"given":"Longyu","family":"Guo","sequence":"additional","affiliation":[{"name":"Electron Microscopy Center, Jilin University, Changchun 130012, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"resources","vocabulary":"credit"},{"role":"validation","vocabulary":"credit"}]},{"given":"Huan","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"data-curation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Sa","family":"Lv","sequence":"additional","affiliation":[{"name":"Key Laboratory of Architectural Cold Climate Energy Management, Ministry of Education, Jilin Jianzhu University, Changchun 130118, China"},{"name":"School of Electrical and Computer Science, Jilin Jianzhu University, Changchun 130118, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"validation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Xiaotian","family":"Yang","sequence":"additional","affiliation":[{"name":"Department of Chemistry, Jilin Normal University, Siping 136000, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"resources","vocabulary":"credit"},{"role":"visualization","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2101783","DOI":"10.1002\/adom.202101783","article-title":"Electrochromic materials based on ions insertion and extraction","volume":"10","author":"Huang","year":"2022","journal-title":"Adv. Opt. Mater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"112037","DOI":"10.1016\/j.solmat.2022.112037","article-title":"Different ion-based electrolytes for electrochromic devices: A review","volume":"248","author":"Ding","year":"2022","journal-title":"Sol. Energy Mater. Sol. Cells"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1039\/D2NR04761F","article-title":"Review on recent progress in WO3-based electrochromic films: Preparation methods and performance enhancement strategies","volume":"15","author":"Zheng","year":"2023","journal-title":"Nanoscale"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"438","DOI":"10.1021\/accountsmr.2c00217","article-title":"Fast-switching WO3-based electrochromic devices: Design, fabrication, and applications","volume":"4","author":"Guo","year":"2023","journal-title":"Acc. Mater. Res."},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Elshorbagy, M.H., and Ramadan, R. (2023). Electrochromic electrodes with enhanced performance: Review of morphology and ion transport mechanism modifications. Energies, 16.","DOI":"10.3390\/en16052327"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"21279","DOI":"10.1039\/D4NR03781B","article-title":"Recent advances in tungsten oxide-based chromogenic materials: Photochromism, electrochromism, and gasochromism","volume":"16","author":"Zhang","year":"2024","journal-title":"Nanoscale"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"4383","DOI":"10.1007\/s12648-024-03199-z","article-title":"A review on perspective of spin coating technique towards profound electrochromism of tungsten oxide thin films","volume":"98","author":"Gupta","year":"2024","journal-title":"Indian J. Phys."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"23295","DOI":"10.1016\/j.ceramint.2020.06.035","article-title":"Trends in sputter deposited tungsten oxide structures for electrochromic applications: A review","volume":"46","author":"Mehmood","year":"2020","journal-title":"Ceram. Int."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"122082","DOI":"10.1016\/j.jssc.2021.122082","article-title":"Electronic properties, optical properties and diffusion behavior of WO3 with H+, Li+ and Na+ intercalated ions: A first-principles study","volume":"297","author":"Cui","year":"2021","journal-title":"J. Solid State Chem."},{"key":"ref_10","first-page":"23567","article-title":"Multivalent-ion versus proton insertion into nanostructured electrochromic WO3 from mild aqueous electrolytes","volume":"16","author":"Rocca","year":"2024","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Zhang, B., Wang, J., Jiang, S., Yuan, M., and Chen, X. (2024). Full spectrum electrochromic WO3 mechanism and optical modulation via ex situ spectroscopic ellipsometry: Effect of Li+ surface permeation. Micromachines, 15.","DOI":"10.3390\/mi15121473"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"20135","DOI":"10.1039\/D5NR02842F","article-title":"Temperature-dependent electrochromic cycling performance of solution-processed WO3 films","volume":"17","author":"Kang","year":"2025","journal-title":"Nanoscale"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"e37094","DOI":"10.1016\/j.heliyon.2024.e37094","article-title":"Visible and near-infrared modulating tungsten suboxide nanorods electrochromic films in acidic aqueous electrolytes","volume":"10","author":"Kwon","year":"2024","journal-title":"Heliyon"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"145542","DOI":"10.1016\/j.electacta.2024.145542","article-title":"Binary solvents of anhydrous ethanol and propylene carbonate for electrolytes of amorphous WO3 films to improve electrochromic performance","volume":"513","author":"Liu","year":"2025","journal-title":"Electrochim. Acta"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"103992","DOI":"10.1016\/j.surfin.2024.103992","article-title":"In situ formation of solid electrolyte interphase for improved cyclability of electrochromic tungsten oxide thin films","volume":"46","author":"Weng","year":"2024","journal-title":"Surf. Interfaces"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"106566","DOI":"10.1016\/j.surfin.2025.106566","article-title":"A robust in-situ solid electrolyte interphase for long-term stable electrochromic WO3 thin films","volume":"66","author":"Fang","year":"2025","journal-title":"Surf. Interfaces"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"19296","DOI":"10.1021\/acs.langmuir.5c01695","article-title":"Bismuth-doped crystalline\/amorphous WO3 composite film: Superior electrochromic performance and structure evolution","volume":"41","author":"Zheng","year":"2025","journal-title":"Langmuir"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"14948","DOI":"10.1021\/acsanm.3c02497","article-title":"Electrochromic smart windows based on nanometer-thick films of WO3 nanowire\/Cu and TiO2\/NiO as composite electrodes","volume":"6","author":"Yu","year":"2023","journal-title":"ACS Appl. Nano Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1363","DOI":"10.1007\/s12598-024-03083-z","article-title":"Microstructural evolution and phase composition of In2Ga2ZnO7 ceramic targets during sintering","volume":"44","author":"Qi","year":"2025","journal-title":"Rare Met."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"4573","DOI":"10.1007\/s12598-024-02800-y","article-title":"A compact route for efficient production of high-purity \u03b2-Ga2O3 powder","volume":"43","author":"Zhou","year":"2024","journal-title":"Rare Met."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Chu, X., Lin, K., Zhao, H., Yao, Z., Chi, Y., Wang, C., and Yang, X. (2025). Biphasic WO3 nanostructures via controlled crystallization: Achieving high-performance electrochromism through amorphous\/crystalline heterointerface design. Crystals, 15.","DOI":"10.3390\/cryst15040324"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"13177","DOI":"10.1039\/D3RA01428B","article-title":"Enhanced electrochromic properties of WO3\/ITO nanocomposite smart windows","volume":"13","author":"An","year":"2023","journal-title":"RSC Adv."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"112226","DOI":"10.1016\/j.solmat.2023.112226","article-title":"Porous WO3\u00b72H2O film with large optical modulation and high coloration efficiency for electrochromic smart window","volume":"253","author":"Zhou","year":"2023","journal-title":"Sol. Energy Mater. Sol. Cells"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"5459","DOI":"10.1021\/acssuschemeng.3c07679","article-title":"Amorphous and crystalline Ti-doped WO3\u00b72H2O for dual-band electrochromic smart windows","volume":"12","author":"Sun","year":"2024","journal-title":"ACS Sustain. Chem. Eng."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"102513","DOI":"10.1016\/j.mtchem.2025.102513","article-title":"Review on amorphous WO3 for electrochromic devices: Structure, optimization strategies and applications","volume":"43","author":"Zhao","year":"2025","journal-title":"Mater. Today Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"48927","DOI":"10.1021\/acsami.4c11641","article-title":"Ionic gel electrolytes for electrochromic devices","volume":"16","author":"Ma","year":"2024","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"751","DOI":"10.1107\/S0567739476001551","article-title":"Revised effective ionic radii and systematic studies of interatomic distances in halides and chalcogenides","volume":"32","author":"Shannon","year":"1976","journal-title":"Acta Crystallogr. Sect. A"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"2300025","DOI":"10.1002\/smsc.202300025","article-title":"The progress and outlook of multivalent-ion-based electrochromism","volume":"3","author":"Xu","year":"2023","journal-title":"Small Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"7442","DOI":"10.1039\/D1RA00125F","article-title":"Aqueous synthesis of tin- and indium-doped WO3 films via evaporation-driven deposition and their electrochromic properties","volume":"11","author":"Uchiyama","year":"2021","journal-title":"RSC Adv."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"615","DOI":"10.1007\/s10853-020-05321-y","article-title":"Electrochromic switching of tungsten oxide films grown by reactive ion-beam sputter deposition","volume":"56","author":"Gies","year":"2021","journal-title":"J. Mater. Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1469","DOI":"10.1021\/acs.accounts.6b00183","article-title":"Next-generation multifunctional electrochromic devices","volume":"49","author":"Cai","year":"2016","journal-title":"Acc. Chem. Res."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"100007","DOI":"10.1016\/j.gerr.2023.100007","article-title":"Recent progress in improving strategies of metal oxide-based electrochromic smart window","volume":"1","author":"Guo","year":"2023","journal-title":"Green Energy Resour."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"369","DOI":"10.1016\/j.nanoms.2022.08.002","article-title":"An overview of recent progress in the development of flexible electrochromic devices","volume":"5","author":"Wang","year":"2023","journal-title":"Nano Mater. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"2200340","DOI":"10.1002\/admi.202200340","article-title":"Real-time mass change: An intrinsic indicator to dynamically probe the electrochemical degradation evolution in WO3","volume":"9","author":"Wang","year":"2022","journal-title":"Adv. Mater. Interfaces"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"1833","DOI":"10.1021\/acsaem.1c03242","article-title":"Understanding electrochemical intercalation of Al3+ cation into the WO3 electrochromic electrode from solid electrolyte interphase and mass changes","volume":"5","author":"Liu","year":"2022","journal-title":"ACS Appl. Energy Mater."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"2300219","DOI":"10.1002\/smsc.202300219","article-title":"The counterbalancing role of oxygen vacancy between the electrochromic properties and the trapping effect passivation for amorphous tungsten oxide films","volume":"4","author":"Zhang","year":"2024","journal-title":"Small Sci."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"5363","DOI":"10.1038\/s41467-023-41097-w","article-title":"Metallic W\/WO2 solid-acid catalyst boosts hydrogen evolution reaction in alkaline electrolyte","volume":"14","author":"Chen","year":"2023","journal-title":"Nat. Commun."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1002\/cssc.201902071","article-title":"Review on recent progress in the development of tungsten oxide based electrodes for electrochemical energy storage","volume":"13","author":"Shinde","year":"2020","journal-title":"ChemSusChem"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"6244","DOI":"10.1002\/anie.201601542","article-title":"Atomistic conversion reaction mechanism of WO3 in secondary ion batteries of Li, Na, and Ca","volume":"55","author":"He","year":"2016","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"e40788","DOI":"10.1016\/j.heliyon.2024.e40788","article-title":"A review on WO3 photocatalysis used for wastewater treatment and pesticide degradation","volume":"11","author":"Kanafin","year":"2025","journal-title":"Heliyon"},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"8","DOI":"10.1007\/s42864-025-00349-6","article-title":"Recent advances in synthesis, performance, and application of oxygen vacancy-enriched WO3\u2212x photocatalysts","volume":"8","author":"He","year":"2026","journal-title":"Tungsten"},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3441","DOI":"10.1007\/s12598-023-02554-z","article-title":"A review on WO3-based composite photocatalysts: Synthesis, catalytic mechanism and diversified applications","volume":"43","author":"Zhang","year":"2024","journal-title":"Rare Met."},{"key":"ref_43","doi-asserted-by":"crossref","unstructured":"Suchikova, Y., Nazarovets, S., Konuhova, M., and Popov, A.I. (2025). Binary oxide ceramics (TiO2, ZnO, Al2O3, SiO2, CeO2, Fe2O3, and WO3) for solar cell applications: A comparative and bibliometric analysis. Ceramics, 8.","DOI":"10.3390\/ceramics8040119"}],"container-title":["Micromachines"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-666X\/17\/9\/1033\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,31]],"date-time":"2026-08-31T04:34:00Z","timestamp":1788150840000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-666X\/17\/9\/1033"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,29]]},"references-count":43,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2026,9]]}},"alternative-id":["mi17091033"],"URL":"https:\/\/doi.org\/10.3390\/mi17091033","relation":{},"ISSN":["2072-666X"],"issn-type":[{"value":"2072-666X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,29]]}}}