Atomic Layer Deposition (ALD) of Alumina over Activated Carbon Electrodes Enabling a Stable 4 V Supercapacitor Operation

Dayakar Gandla, Guanghui Song, Chongrui Wu, Yair Ein-Eli, Daniel Q. Tan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Designing high voltage (>3 V) and stable electrochemical supercapacitors with low self-discharge is desirable for the applications in modern electronic devices. This work demonstrates a 4 V symmetric supercapacitor with stabilized cycling performance through atomic layer deposition (ALD) of alumina (Al2O3) on the surface of activated carbon (AC). The 20-cycle ALD Al2O3 coated AC delivers 84 % capacitance retention after 1000 charge/discharge cycles under 4 V, contrary to the bare AC cells having only 48 % retention. The extended cycling life is associated with the thickened Stern layer and suppressed oxygen functional group. The self-discharge data also show that the Al2O3 coating enables AC cells to maintain 53 % of charge retention after 12 h, which is more than twice higher than that of bare AC cells under the same test protocol of 4 V charging. The curve fitting analysis reveals that ALD coating induced slow self-discharge dominated by ion diffusion mechanism, thus enhancing the AC surface energy.

Original languageEnglish
Pages (from-to)402-407
Number of pages6
JournalChemistryOpen
Volume10
Issue number4
DOIs
StatePublished - Apr 2021

Keywords

  • activated carbon
  • atomic layer deposition
  • high voltage
  • self-discharge
  • supercapacitors

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