Polyvinyl alcohol-acid redox active gel electrolytes for electrical double-layer capacitor devices

Since the mechanism of charge storage in electrical double-layer capacitors (EDLCs) relies on diffusion of ions into the pores of the electrodes, in general, a much lower capacitance is expected for gel-based electrolytes than liquid electrolytes. However, in this work, we have found that the specif...

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Bibliographic Details
Published in:Journal of solid state electrochemistry 2019-01, Vol.23 (1), p.125-133
Main Authors: Aljafari, Belqasem, Alamro, Turki, Ram, Manoj K., Takshi, Arash
Format: Article
Language:English
Subjects:
Analytical Chemistry
Capacitance
Capacitors
Characterization and Evaluation of Materials
Chemistry
Chemistry and Materials Science
Condensed Matter Physics
Diffusion layers
Electrochemical impedance spectroscopy
Electrochemistry
Electrolytes
Energy Storage
Ion diffusion
Original Paper
Physical Chemistry
Polyvinyl alcohol
Sulfuric acid
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Summary:Since the mechanism of charge storage in electrical double-layer capacitors (EDLCs) relies on diffusion of ions into the pores of the electrodes, in general, a much lower capacitance is expected for gel-based electrolytes than liquid electrolytes. However, in this work, we have found that the specific capacitance in gel-based electrolytes made of polyvinyl alcohol (PVA) and an acid (H 2 SO 4 or H 3 PO 4 ) is even higher than the specific capacitances of similar devices with liquid acid-based electrolytes. We have discovered that the reason is due to the gel being a redox active material with the capability of charge storage in the volume of the electrolyte. In this work, solid-state and flexible devices with both H 2 SO 4 -PVA and H 3 PO 4 –PVA electrolytes were fabricated and characterized. The cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) methods were applied to estimate the capacitance associated to the gel electrolytes. Also, a relatively high cycling stability of 97.5% for H 2 SO 4 -PVA and 95% for H 3 PO 4 -PVA was obtained after 1000 charging-discharging cycles. A mechanism of charge storage is proposed to explain the redox active behavior of the gel electrolyte. The presented results are promising for employment of PVA gel electrolytes in some low-cost applications.
ISSN:1432-8488
1433-0768
DOI:10.1007/s10008-018-4120-y