Electrochemical Quartz Crystal Microbalance (EQCM) Study of Ion Dynamics in Nanoporous Carbons

Wan-Yu Tsai (1, 2) , Pierre-Louis Taberna (1, 2) , Patrice Simon (1, 2)

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

Electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry (CV) measurements were used to characterize ion adsorption in carbide-derived carbon (CDC) with two different average pore sizes (1 and 0.65 nm), from neat and solvated 1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (EMI-TFSI) electrolytes. From the electrode mass change in neat EMI-TFSI, it was shown that one net charge stored corresponds almost to one single ion at high polarization; in that case, no ion-pairing or charge screening by co-ions were observed. In 2 M EMI-TFSI in acetonitrile electrolyte, experimental solvation numbers were estimated for EMI+ cation, showing a partial desolvation when cations were adsorbed in confined carbon pores. The extent of desolvation increased when decreasing the carbon pore size (from 1 down to 0.65 nm). The results also suggest that EMI+ cation owns higher mobility than TFSI- anion in these electrolytes.

Mots clés: Electrochemical Quartz Crystal Microbalance EQCM; Ion; Nanoporous Carbons

Domaines: Matériaux; Matériaux

Wan-Yu Tsai, Pierre-Louis Taberna, Patrice Simon. Electrochemical Quartz Crystal Microbalance (EQCM) Study of Ion Dynamics in Nanoporous Carbons. Journal of the American Chemical Society, 2014, 136 (24), pp.8722-8728. ⟨10.1021/ja503449w⟩. ⟨hal-03522653⟩