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Understanding how non-delaminated MXene particles undergo interlayer structural evolution during repeated ion insertion\/extraction is essential for designing electrodes that utilize nanoscale ion confinement. Although the charge-storage behavior of Lewis-acidic ions such as Li+ and H+ in MXenes has been extensively investigated, that of bulky tetraalkylammonium ions remains largely unexplored. Here, we clarify the charge-storage behavior of tetraethylammonium cations (TEA+) in the interlayer space of non-delaminated Ti3C2Tx MXene. Repeated CV cycling drives TEA+-associated charge storage within nanosized MXene particles, accompanied by progressive interlayer expansion and enhanced specific capacitance. Structural analysis using a simplified geometrical model reveals how the relative sizes of the ion and solvent molecule correlate with the interlayer spacing of MXene. These findings provide insights into confined ion\u2013MXene interlayer structures and offer a strategy for enhancing the charge-storage activity of non-delaminated MXene electrodes with bulky organic cations.<\/jats:p>","DOI":"10.1021\/acsami.6c13880","type":"journal-article","created":{"date-parts":[[2026,9,11]],"date-time":"2026-09-11T13:01:36Z","timestamp":1789131696000},"page":"51027-51034","source":"Crossref","is-referenced-by-count":0,"title":["Electrochemically Activated Charge Storage of Tetraalkylammonium Cations Confined in Non-Delaminated MXene Interlayers"],"prefix":"10.1021","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3840-2198","authenticated-orcid":true,"given":"Kosuke","family":"Kawai","sequence":"first","affiliation":[{"name":"Waseda University , , 3-4-1, Okubo, Shinjuku-Ku , ,","place":["Tokyo, Japan, 169-8555"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kosei","family":"Ohura","sequence":"additional","affiliation":[{"name":"Panasonic Holdings Corporation , , 3-1-1 Yagumo-Nakamachi , , ,","place":["Moriguchi, Osaka, Japan, 570-8501"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3388-7042","authenticated-orcid":true,"given":"Hiroyuki","family":"Koshikawa","sequence":"additional","affiliation":[{"name":"Panasonic Holdings Corporation , , 3-1-1 Yagumo-Nakamachi , , ,","place":["Moriguchi, Osaka, Japan, 570-8501"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6058-2917","authenticated-orcid":true,"given":"Ryosuke","family":"Kikuchi","sequence":"additional","affiliation":[{"name":"Panasonic Holdings Corporation , , 3-1-1 Yagumo-Nakamachi , , ,","place":["Moriguchi, Osaka, Japan, 570-8501"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7741-5234","authenticated-orcid":true,"given":"Masashi","family":"Okubo","sequence":"additional","affiliation":[{"name":"Waseda University , , 3-4-1, Okubo, Shinjuku-Ku , ,","place":["Tokyo, Japan, 169-8555"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,11]]},"reference":[{"key":"2026102013074168400_cit1","doi-asserted-by":"publisher","DOI":"10.1002\/aesr.202400412","article-title":"Supercapacitors: An Emerging Energy Storage System","volume":"6","author":"Iqbal","year":"2025","journal-title":"Adv. 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