Influence of electrolyte on the photo-charging capability of a ZnO-FTO supercapacitor

Chauhan, PS and Parekh, M and Sahoo, S and Kumar, S and Mahapatra, AD and Sharma, P and Panwar, V and Rao, AM and Misra, A (2024) Influence of electrolyte on the photo-charging capability of a ZnO-FTO supercapacitor. In: Journal of Materials Chemistry A, 12 . pp. 22725-22736.

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Abstract

Photo-rechargeable supercapacitors serve as a bridge between batteries and solar cells for developing efficient energy storage devices. Unlike previous studies where there was either (a) a heterostructure of zinc oxide (ZnO) with other electroactive materials or (b) a coating of ZnO powder on the current collector, here, ZnO nanorods grown on fluorine-doped tin oxide (FTO) were used as photoelectrodes. Our devices tested with (i) an ionic liquid electrolyte and (ii) a gel electrolyte exhibited a capacitance rise of �3006 (>10� the previous record) and �500 (2� the previous record) compared to that under dark conditions, which is attributed to the electrode synthesis technique adopted in this study. A higher ionic diffusivity in the ionic liquid electrolyte leads to a higher capacitance rise. Notably, a novel necking behavior (a possibly higher incremental capacitance at higher voltages) was observed during galvanostatic charge/discharge tests under UV illumination for both electrolytes, which is attributed to the high electrode porosity. Contrary to conventional wisdom, higher capacitance was recorded at higher current densities during galvanostatic charge/discharge tests under UV illumination for ionic liquid-based supercapacitor cells. A first-ever physics-based continuum scale model for photo-rechargeable supercapacitors is proposed to explain the above intriguing experimental observations, paving a path for the design of fast-charging high-capacitance supercapacitors. © 2024 The Royal Society of Chemistry.

Item Type:	Journal Article
Publication:	Journal of Materials Chemistry A
Publisher:	Royal Society of Chemistry
Additional Information:	The copyright for this article belongs to the Royal Society of Chemistry.
Keywords:	Charging (batteries); Ductile fracture; Electrodes; II-VI semiconductors; Ionic liquids; Nanocomposites; Nanorods; Solid electrolytes; Supercapacitor; Tin oxides; Zinc oxide, Charge discharge tests; Current-collector; Electroactive material; Fluorine doped-tin oxides; Galvanostatic charge/discharge; Ionic liquid electrolytes; Photocharging; UV illuminations; Zinc oxide nanorods; Zinc oxide powder, Capacitance
Department/Centre:	Division of Physical & Mathematical Sciences > Instrumentation Appiled Physics
Date Deposited:	09 Sep 2024 10:10
Last Modified:	09 Sep 2024 10:10
URI:	http://eprints.iisc.ac.in/id/eprint/86051

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