title: Highly confined ions store charge more efficiently in supercapacitors.
abstract: Liquids exhibit specific properties when they are adsorbed in nanoporous structures. This is particularly true in the context of supercapacitors, for which an anomalous increase in performance has been observed for nanoporous electrodes. This enhancement has been traditionally attributed in experimental studies to the effect of confinement of the ions from the electrolyte inside sub-nanometre pores, which is accompanied by their partial desolvation. Here we perform molecular dynamics simulations of realistic supercapacitors and show that this picture is correct at the microscopic scale. We provide a detailed analysis of the various environments experienced by the ions. We pick out four different adsorption types, and we, respectively, label them as edge, planar, hollow and pocket sites upon increase of the coordination of the molecular species by carbon atoms from the electrode. We show that both the desolvation and the local charge stored on the electrode increase with the degree of confinement.
authors.affiliation: 1] UPMC Univ Paris 06, CNRS, ESPCI, UMR 7195, PECSA, F-75005 Paris, France [2] Réseau sur le Stockage Electrochimique de l'Energie (RS2E), FR CNRS 3459, France.
authors.forename: C
authors.initials: C
authors.lastname: Merlet
authors.forename: C
authors.initials: C
authors.lastname: Péan
authors.forename: B
authors.initials: B
authors.lastname: Rotenberg
authors.forename: P A
authors.initials: PA
authors.lastname: Madden
authors.forename: B
authors.initials: B
authors.lastname: Daffos
authors.forename: P-L
authors.initials: PL
authors.lastname: Taberna
authors.forename: P
authors.initials: P
authors.lastname: Simon
authors.forename: M
authors.initials: M
authors.lastname: Salanne