Self-discharge of AC/AC electrochemical capacitors in salt aqueous electrolyte. (1st June 2016)

• Record Type: Journal Article
• Authors: García-Cruz, L.; Ratajczak, P.; Iniesta, J.; Montiel, V.; Béguin, F.
• Is Part Of: Electrochimica acta. Volume 202(2016)
• Page Start: 66
• Page End: 72
• Publication Date: 2016-06-01
• Subjects: Self-discharge -- AC/AC electrochemical capacitor -- aqueous lithium sulfate electrolyte -- diffusion-controlled mechanism -- activation-controlled mechanism; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2016.03.159
• Languages: English
• ISSNs: 0013-4686

Abstract

Abstract: The self-discharge (SD) of electrochemical capacitors based on activated carbon electrodes (AC/AC capacitors) in aqueous lithium sulfate was examined after applying a three-hour cell potential hold at Ui values from 1.0 to 1.6 V. The leakage current measured during the potentiostatic period as well as the amplitude of self-discharge increased with Ui ; the cell potential drop was approximately doubled by 10 °C increase of temperature. The potential decay of both negative and positive electrodes was explored separately, by introducing a reference electrode and it was found that the negative electrode contributes essentially to the capacitor self-discharge. A diffusion-controlled mechanism was found at Ui ≤ 1.4 V and Ui ≤ 1.2 V for the positive and negative electrodes, respectively. At higher Ui of 1.6 V, both electrodes display an activation-controlled mechanism due to water oxidation and subsequent carbon oxidation at the positive electrode and water or oxygen reduction at the negative electrode.