Electric double-layer capacitance between an ionic liquid and few-layer graphene

Eri Uesugi, Hidenori Goto, Ritsuko Eguchi, Akihiko Fujiwara, Yoshihiro Kubozono

Research output: Contribution to journalArticle

97 Citations (Scopus)

Abstract

Ionic-liquid gates have a high carrier density due to their atomically thin electric double layer (EDL) and extremely large geometrical capacitance C g. However, a high carrier density in graphene has not been achieved even with ionic-liquid gates because the EDL capacitance C EDL between the ionic liquid and graphene involves the series connection of C g and the quantum capacitance C q, which is proportional to the density of states. We investigated the variables that determine C EDL at the molecular level by varying the number of graphene layers n and thereby optimising C q. The C EDL value is governed by C q at n < 4, and by C g at n > 4. This transition with n indicates a composite nature for C EDL. Our finding clarifies a universal principle that determines capacitance on a microscopic scale, and provides nanotechnological perspectives on charge accumulation and energy storage using an ultimately thin capacitor.

Original languageEnglish
Article number1595
JournalScientific reports
Volume3
DOIs
Publication statusPublished - 2013

ASJC Scopus subject areas

  • General

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