doi:10.1016/j.jpowsour.2025.238098engAina, SergioSlesinski, AdamCherkaoui, AbdenbiSlesinska, SylwiaLobera, M. PilarFrackowiak, ElzbietaBernechea, MaríaEnhanced stability of high energy aqueous capacitor based on redox-active nanomaterials and electrolyteART-2025-145092The incorporation of redox-active species can deliver high-energy-density aqueous electrochemical capacitors by simultaneously enhancing capacitance and voltage. Building on a previously reported double-redox capacitor combining a YP50F porous carbon functionalized with Bi2S3 nanorods (NRs) as the negative electrode, a pristine YP50F positive electrode, and a 1M NaI electrolyte, in this work we investigated the effect of reducing Bi2S3 particle size and increasing its loading. Incorporating 15 % wt. Bi2S3 nanoparticles (NPs) delivered a capacitance of 235 F g−1 at 0.5 A g−1 and 193 F g−1 at 10 A g−1, outperforming the device with a 10 % wt. NPs loading and the NRs-based hybrid at high rates. The energy output of the full cell (18.3 Wh kg−1) surpassed other aqueous devices using carbon-based or other bismuth-based anodes. Despite this improvement, the device lost 20 % of its initial capacitance after only 60 charge-discharge cycles. Electrolyte buffering and pre-iodination of the YP50F in the positive electrode improved the stability, yielding 100 % capacitance retention after 1000 cycles. Post-mortem ex situ XPS analysis revealed that these treatments suppress iodate/periodate formation and prevents oxidation of Bi-S species to sulfates, mitigating corrosion and precipitation, and securing long-term stability.2025http://zaguan.unizar.es/record/16252010.1016/j.jpowsour.2025.238098http://zaguan.unizar.es/record/162520oai:zaguan.unizar.es:162520info:eu-repo/grantAgreement/ES/AEI/CEX2023-001286-Sinfo:eu-repo/grantAgreement/ES/AEI/PID2023-150574NB-I00info:eu-repo/grantAgreement/ES/UZ/UZ2023-IyA-01JOURNAL OF POWER SOURCES 657 (2025), 238098 [10 pp.]by-nchttps://creativecommons.org/licenses/by-nc/4.0/deed.esinfo:eu-repo/semantics/openAccess