Title
Ambiguous Role of Cations in the Long-Term Performance of Electrochemical Capacitors with Aqueous Electrolytes
Authors
[ 1 ] Instytut Chemii i Elektrochemii Technicznej, Wydział Technologii Chemicznej, Politechnika Poznańska | [ P ] employee
Scientific discipline (Law 2.0)
Year of publication
2023
Published in
Article type
scientific article
Publication language
english
Keywords
EN
- electrochemical capacitor
- aqueous electrolyte
- sulfate-based capacitors
- aging
- prolonged lifetime
- activated carbon electrode
Abstract
EN A comprehensive comparison of electrochemical capacitors (ECs) with various aqueous alkali metal sulfate solutions (Li2SO4, Na2SO4, Rb2SO4, and Cs2SO4) is reported. The EC with a less conductive 1 mol L–1 Li2SO4 solution demonstrates the best long-term performance (214 h floating test) compared to the EC with a highly conductive 1 mol L–1 Cs2SO4 solution (200 h). Both the positive and negative EC electrodes are affected by extensive oxidation and hydrogen electrosorption, respectively, during the aging process, as proven by the SBET fade. Interestingly, carbonate formation is observed as a minor cause of aging. Two strategies for optimizing sulfate-based ECs are proposed. In the first approach, Li2SO4 solutions with the pH adjusted to 3, 7, and 11 are investigated. The sulfate solution alkalization inhibits subsequent redox reactions, and as a result, EC performance is successfully enhanced. The second approach exploits so-called bication electrolytic solutions based on a mixture of Li2SO4 and Na2SO4 at an equal concentration. This concept allows the operational time to be significantly prolonged, up to 648 h (+200% compared to 1 mol L–1 Li2SO4). Therefore, two successful pathways for improving sulfate-based ECs are demonstrated.
Date of online publication
04.05.2023
Pages (from - to)
23860 - 23874
License type
CC BY (attribution alone)
Open Access Mode
czasopismo hybrydowe
Open Access Text Version
final published version
Release date
04.05.2023
Date of Open Access to the publication
at the time of publication
Full text of article
Access level to full text
public
Ministry points / journal
200
Impact Factor
8,3
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