The buffer effect in neutral electrolyte supercapacitors

Steffen Thrane Vindt*, Eivind M. Skou

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The observation that double-layer capacitors based on neutral aqueous electrolytes can have significantly wider usable potential windows than those based on acidic or alkaline electrolytes is studied. This effect is explained by a local pH change taking place at the electrode surfaces, leading to a change in the redox potential of water in opposite directions on the two electrodes, resulting in the wider stability window. The magnitude of this effect is suggested to be dependent on the buffer capacity, rather than the intrinsic pH value of the electrolyte. This is confirmed by studying the impact of addition of a buffer to such systems. It is shown that a 56 % higher dynamic storage capacity may be achieved, simply by controlling the buffer capacity of the electrolyte. The model system used, is based on a well-known commercial activated carbon (NORIT™ A SUPRA) as the electrode material, aqueous potassium nitrate as the electrolyte and potassium phosphates as the buffer system.

Translated title of the contributionBuffereffekten i superkondensatorer med neutrale elektrolyter
Original languageEnglish
Article number64
JournalApplied Physics A
Volume122
Issue number2
Number of pages6
ISSN0947-8396
DOIs
Publication statusPublished - 1. Feb 2016

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