Ambiguous Role of Cations in the Long-Term Performance of Electrochemical Capacitors with Aqueous Electrolytes

• DOI: 10.1021/acsami.2c21926
• Publication Date: 2023-05-05T00:44:32Z
• Authors: Anetta Platek-Mie...; Justyna Piwek; Elzbieta Frackowiak; Krzysztof Fic
• Keywords: Lithium sulfate; Sodium sulfate

A comprehensive comparison of electrochemical capacitors (ECs) with various aqueous alkali metal sulfate solutions (Li2SO4, Na2SO4, Rb2SO4, and Cs2SO4) is reported. The EC a less conductive 1 mol L-1 Li2SO4 solution demonstrates the best long-term performance (214 h floating test) compared to highly Cs2SO4 (200 h). Both positive negative electrodes are affected by extensive oxidation hydrogen electrosorption, respectively, during aging process, as proven SBET fade. Interestingly, carbonate formation observed minor cause aging. Two strategies for optimizing sulfate-based ECs proposed. In first approach, pH adjusted 3, 7, 11 investigated. alkalization inhibits subsequent redox reactions, result, successfully enhanced. second approach exploits so-called bication electrolytic based on mixture Na2SO4 at an equal concentration. This concept allows operational time be significantly prolonged, up 648 (+200% Li2SO4). Therefore, two successful pathways improving demonstrated.