Metakaolin Composite Supercapacitors: A Transformative Approach to Reshaping Urban Energy Systems

Metakaolin Composite Supercapacitors: A Transformative Approach to Reshaping Urban Energy Systems | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Metakaolin Composite Supercapacitors: A Transformative Approach to Reshaping Urban Energy Systems Feifei Zhang, Yong Yu, Yong Luo, Jing Wang, Zihui Zhang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9465886/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 8 You are reading this latest preprint version Abstract To address the inherent trade-off between enhanced electrical conductivity and reduced mechanical performance in geopolymer-based energy storage materials, carbon black was used as a conductive filler, while the contents of sodium hydroxide, metakaolin, sodium silicate and alkali activator were systematically optimized to develop geopolymer composites. Mechanical testing, electrochemical impedance spectroscopy, cyclic voltammetry (CV) and galvanostatic charge–discharge were conducted to evaluate the coupled mechanical–electrochemical performance. The optimal formulation comprises 5 parts carbon black, 8.4 parts sodium hydroxide, 41.6 parts metakaolin and 45 parts sodium silicate, with an alkali activator content of 53.4%. Under these conditions, the compressive strength remains 31.7–33.2 MPa, while the specific capacitance reaches 72.5–78.3 F/g, representing a 50.8% increase compared with low-carbon-black systems, with only a 3.6% strength reduction. Moreover, the CV curves exhibit high rectangularity (8.8–9.2), capacitance retention after 1000 cycles remains 94.2%–94.6% and ionic conductivity reaches 9.53×10⁻⁴–1.04×10⁻³ S/m, indicating excellent electrochemical reversibility and cycling stability. Compared with existing studies, the proposed formulation requires no additional modifiers, offering lower cost, simpler processing and improved synergy between mechanical and energy storage properties, thereby mitigating the conventional trade-off. This study provides valuable guidance for mix design optimization and practical application of geopolymer-based structural energy storage materials. Physical sciences/Chemistry Physical sciences/Energy science and technology Physical sciences/Engineering Physical sciences/Materials science Energy storage geopolymer Carbon black Specific capacitance Ionic conductivity Electrochemical performance Full Text Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviewers agreed at journal 16 May, 2026 Reviews received at journal 05 May, 2026 Reviewers agreed at journal 28 Apr, 2026 Reviewers invited by journal 27 Apr, 2026 Editor assigned by journal 27 Apr, 2026 Editor invited by journal 27 Apr, 2026 Submission checks completed at journal 24 Apr, 2026 First submitted to journal 24 Apr, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-9465886","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":634760188,"identity":"d2aa3d1c-bf68-46a5-a10e-6b9100bd2d6d","order_by":0,"name":"Feifei Zhang","email":"","orcid":"","institution":"Longyan University","correspondingAuthor":false,"prefix":"","firstName":"Feifei","middleName":"","lastName":"Zhang","suffix":""},{"id":634760189,"identity":"4dc46d5b-3b9b-4440-8cbc-90e36eafe1e2","order_by":1,"name":"Yong Yu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA7UlEQVRIiWNgGAWjYPACCTl+ZuYDH0BMNnbitFgYS7a3Jc4Aa2EmTktF4oYzZwzBWhgIaTG4kWP4uOCXROKGGzkfGz62bZPnY2Zg/PAxB68WY+OZfRLGM2/kbmyccea2YRszA7PkzG14tZhJ8/ZIyPbdyN3+mKfiNiNQCxszLxFaGBtu5Dxs5jG4bU+cFp4fEooTzpxhbAbakkhQi+SZZ8XGvA0SoEA2BPkluY2ZsRmvX/iOJ298zPOnDhSVD4Ehdtt2fnvzwQ8f8WhROMBhwMDYhiLG2IBbPRDIN7A/YGD4g1fNKBgFo2AUjHQAAE/2VdZoXRa7AAAAAElFTkSuQmCC","orcid":"","institution":"Guangzhou Maritime University","correspondingAuthor":true,"prefix":"","firstName":"Yong","middleName":"","lastName":"Yu","suffix":""},{"id":634760190,"identity":"1f1fa710-783a-429f-94fe-16fcc4ddb9e8","order_by":2,"name":"Yong Luo","email":"","orcid":"","institution":"Yiwu City Commercial Concrete Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Yong","middleName":"","lastName":"Luo","suffix":""},{"id":634760192,"identity":"f1d4d578-9b13-4da8-a4fb-312f2fab1aec","order_by":3,"name":"Jing Wang","email":"","orcid":"","institution":"Yiwu Sanshi New Materials Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Jing","middleName":"","lastName":"Wang","suffix":""},{"id":634760194,"identity":"172aa913-83d8-46f7-a5f2-a7e10888fe72","order_by":4,"name":"Zihui Zhang","email":"","orcid":"","institution":"Yiwu Sanshi New Materials Co., Ltd.","correspondingAuthor":false,"prefix":"","firstName":"Zihui","middleName":"","lastName":"Zhang","suffix":""}],"badges":[],"createdAt":"2026-04-20 02:53:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9465886/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9465886/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":108622376,"identity":"8a52fd54-b00b-4e29-bded-3216827bfc06","added_by":"auto","created_at":"2026-05-06 14:57:33","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":898034,"visible":true,"origin":"","legend":"","description":"","filename":"Manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9465886/v1_covered_4e1198d4-3ac7-4cbb-9bc4-b46bb566ea0a.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Metakaolin Composite Supercapacitors: A Transformative Approach to Reshaping Urban Energy Systems","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Energy storage geopolymer, Carbon black, Specific capacitance, Ionic conductivity, Electrochemical performance","lastPublishedDoi":"10.21203/rs.3.rs-9465886/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9465886/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"To address the inherent trade-off between enhanced electrical conductivity and reduced mechanical performance in geopolymer-based energy storage materials, carbon black was used as a conductive filler, while the contents of sodium hydroxide, metakaolin, sodium silicate and alkali activator were systematically optimized to develop geopolymer composites. Mechanical testing, electrochemical impedance spectroscopy, cyclic voltammetry (CV) and galvanostatic charge–discharge were conducted to evaluate the coupled mechanical–electrochemical performance. The optimal formulation comprises 5 parts carbon black, 8.4 parts sodium hydroxide, 41.6 parts metakaolin and 45 parts sodium silicate, with an alkali activator content of 53.4%. Under these conditions, the compressive strength remains 31.7–33.2 MPa, while the specific capacitance reaches 72.5–78.3 F/g, representing a 50.8% increase compared with low-carbon-black systems, with only a 3.6% strength reduction. Moreover, the CV curves exhibit high rectangularity (8.8–9.2), capacitance retention after 1000 cycles remains 94.2%–94.6% and ionic conductivity reaches 9.53×10⁻⁴–1.04×10⁻³ S/m, indicating excellent electrochemical reversibility and cycling stability. 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