Amorphous aluminum-oxide supercapacitors

Mikio Fukuhara, Tomoyuki Kuroda, Fumihiko Hasegawa, Toshiyuki Hashida, Eunsang Kwon, Kazuya Konno

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

An amorphous aluminium-oxide supercapacitor can store a large amount of electric charge on its blackish, uneven Al2O3-x surface, which has a convexity of 21 nm, AlO6 clusters, and a resistivity of 16.5 Gωcm. The electric storage can be elucidated by extremely enhanced electron trapping resulting from both the quantum-size effect and the offset effect of the positive charges at O-vacancy sites. Here, a supercapacitor, characterised by a high surface area of ∼ 2,400m2 and the formation of large numbers of electric double layers, demonstrates a vertical line in the Nyquist diagram, corresponding to rapidly increased imaginary impedance and phase angle of -90° with decreasing frequency in the Bode diagram using a distributed constant-electric circuit with a parallel assembly of nanometer-sized capacitors on a highly insulating amorphous aluminium surface. The supercapacitor indicates a switching effect for both positive (∼ +66V)and negative (∼ -11V)potentials. Thus, we can apply rechargeable dry solid supercapacitors in place of practical Li ions.

Original languageEnglish
Article number58004
JournalEPL
Volume123
Issue number5
DOIs
Publication statusPublished - 2018 Sep

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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