title: Exploring electrolyte organization in supercapacitor electrodes with solid-state NMR.
abstract: Supercapacitors are electrochemical energy-storage devices that exploit the electrostatic interaction between high-surface-area nanoporous electrodes and electrolyte ions. Insight into the molecular mechanisms at work inside supercapacitor carbon electrodes is obtained with (13)C and (11)B ex situ magic-angle spinning nuclear magnetic resonance (MAS-NMR). In activated carbons soaked with an electrolyte solution, two distinct adsorption sites are detected by NMR, both undergoing chemical exchange with the free electrolyte molecules. On charging, anions are substituted by cations in the negative carbon electrode and cations by anions in the positive electrode, and their proportions in each electrode are quantified by NMR. Moreover, acetonitrile molecules are expelled from the adsorption sites at the negative electrode alone. Two nanoporous carbon materials were tested, with different nanotexture orders (using Raman and (13)C MAS-NMR spectroscopies), and the more disordered carbon shows a better capacitance and a better tolerance to high voltages.
authors: CNRS, UPR3079 CEMHTI, Orléans, France. michael.deschamps@cnrs-orleans.fr
authors: Michaël
authors: M
authors: Deschamps
authors: Edouard
authors: E
authors: Gilbert
authors: Philippe
authors: P
authors: Azais
authors: Encarnación
authors: E
authors: Raymundo-Piñero
authors: Mohammed Ramzi
authors: MR
authors: Ammar
authors: Patrick
authors: P
authors: Simon
authors: Dominique
authors: D
authors: Massiot
authors: François
authors: F
authors: Béguin