title: Anomalous capacitive behaviors of graphene oxide based solid-state supercapacitors.
abstract: Substantial differences in charge storage mechanisms exist between dielectric capacitors (DCs) and electrochemical capacitors (ECs), resulting in orders of magnitude difference of stored charge density in them. However, if ionic diffusion, the major charge transport mechanism in ECs, is confined within nanoscale dimensions, the Helmholtz layers and diffusion layers will overlap, resulting in dismissible ionic diffusion. An interesting contradiction between appreciable energy density and unrecognizable ionic diffusion is observed in solid-state capacitors made from reduced graphene oxide films that challenge the fundamental charge storage mechanisms proposed in such devices. A new capacitive model is proposed, which combines the two distinct charge storage mechanisms of DCs and ECs, to explain the contradiction, of high storage capacity yet undetectable ionic diffusion, seen in graphene oxide based supercapacitors.
authors.affiliation: Department of Mechanical Engineering, University of Delaware , Newark, Delaware 19716, United States.
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhang
authors.forename: Kathryn
authors.initials: K
authors.lastname: Scrafford
authors.forename: Mingtao
authors.initials: M
authors.lastname: Li
authors.forename: Zeyuan
authors.initials: Z
authors.lastname: Cao
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Xia
authors.forename: Pulickel M
authors.initials: PM
authors.lastname: Ajayan
authors.forename: Bingqing
authors.initials: B
authors.lastname: Wei