On the molecular origin of supercapacitance in nanoporous carbon electrodes

Céline Merlet (1, 2) , Benjamin Rotenberg (1, 2) , Paul Anthony Madden (3) , Pierre-Louis Taberna (2, 4) , Patrice Simon (2, 4) , Yury Gogotsi (5) , Mathieu Salanne (1, 2)

1 PECSA - Physicochimie des Electrolytes, Colloïdes et Sciences Analytiques
2 RS2E - Réseau sur le stockage électrochimique de l'énergie
3 University of Oxford
4 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
5 Drexel University

Lightweight, low-cost supercapacitors with the capability of rapidly storing a large amount of electrical energy can contribute to meeting continuous energy demands and effectively levelling the cyclic nature of renewable energy sources1. The excellent electrochemical performance of supercapacitors is due to a reversible ion adsorption in porous carbon electrodes. Recently, it was demonstrated that ions from the electrolyte could enter sub nanometre pores, greatly increasing the capacitance2, 3, 4. However, the molecular mechanism of this enhancement remains poorly understood. Here we provide the first quantitative picture of the structure of an ionic liquid adsorbed inside realistically modelled microporous carbon electrodes. We show how the separation of the positive and negative ions occurs inside the porous disordered carbons, yielding much higher capacitance values (125 F g−1) than with simpler electrode geometries5. The proposed mechanism opens the door for the design of materials with improved energy storage capabilities. It also sheds new light on situations where ion adsorption in porous structures or membranes plays a role.

Mots clés: Molecular origin; Supercapacitance; Nanoporous carbon electrodes

Domaines: Matériaux; Matériaux

Céline Merlet, Benjamin Rotenberg, Paul Anthony Madden, Pierre-Louis Taberna, Patrice Simon, et al.. On the molecular origin of supercapacitance in nanoporous carbon electrodes. Nature Materials, 2012, vol. 11 (n° 4), pp. 306-310. ⟨10.1038/NMAT3260⟩. ⟨hal-01153072⟩