An Artificial Interface for High Cell Voltage Aqueous-Based Electrochemical Capacitors

Marco Olarte (1) , Marie-Joëlle Menu (1) , Patrice Simon (1, 2) , Marie Gressier (1) , Pierre-Louis Taberna (1, 2)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
2 RS2E - Réseau sur le stockage électrochimique de l'énergie

Aqueous electrolytes are very effective for supercapacitor applications but their narrow electrochemical potential window (∼1 V) and associated limited energy currently limits their use. Here, we demonstrate a new strategy to enlarge the potential window by designing an artificial interface (ai). An effective ai was achieved via a mixture of siloxanes doped with an ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMI TFSI). Indeed, the as-deposited ai on the carbon-based electrode hinders the electron charge transfer but not the ionic charge transfer, making the ai ionic conductive. As a result, a cell voltage of about 1.8 V was obtained in aqueous electrolyte-EMI HSO4 1 mol l−1 in water. Used as a membrane, the ai was found to be ionically specific to EMI+; the proton transference number being close to zero. These results show the strategy of developing an ai at the electrode/electrolyte interface could represent a new path for aqueous-based carbon-carbon supercapacitors to reach higher cell voltages, providing both higher specific energy and power.

Mots clés: High Cell Voltage; Electrochemical Capacitors

Domaines: Autre; Energie électrique

Marco Olarte, Marie-Joëlle Menu, Patrice Simon, Marie Gressier, Pierre-Louis Taberna. An Artificial Interface for High Cell Voltage Aqueous-Based Electrochemical Capacitors. Journal of The Electrochemical Society, 2021, 168 (7), pp.070520. ⟨10.1149/1945-7111/ac10f5⟩. ⟨hal-03371278⟩