Micro-corrugated graphene sheet enabled high-performance all-solid-state film supercapacitor

All-solid-state flexible graphene-based film supercapacitors have been widely studied thanks to the extraordinary features of graphene and ever-growing interest in wearable electronics. However, strong π-π interactions between graphene sheets decrease the accessible surface area for electrolyte ions...

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Bibliographic Details
Published in:Carbon (New York) 2020-04, Vol.160, p.156-163
Main Authors: Wu, Dao-Yi, Zhou, Wen-Hua, He, Lin-Yi, Tang, Hai-Yan, Xu, Xiao-Hui, Ouyang, Quan-Sheng, Shao, Jiao-Jing
Format: Article
Language:English
Subjects:
Corrugated sheet
Electrochemical analysis
Electrodes
Flexible supercapacitor
Flux density
Functional groups
Graphene
Graphene film
Graphite
Interlayer spacer
Interlayers
Morphology
Nanocomposites
Sheets
Solid state
Supercapacitors
Surface area
Thin films
Water chemistry
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Summary:All-solid-state flexible graphene-based film supercapacitors have been widely studied thanks to the extraordinary features of graphene and ever-growing interest in wearable electronics. However, strong π-π interactions between graphene sheets decrease the accessible surface area for electrolyte ions, which impairs the electrochemical performance. To address this issue, a graphene oxide (GO)-based gel film precursor was directly reduced in a liquid, and the water molecules between the GO sheets behave as interlayer spacers, which significantly lowers the interlayer attractive force and the frictional force. The graphene sheets shrink as the result of the in-plane contraction forces because of the removal of functional groups on the GO sheets during reduction, leading to a freestanding and corrugated graphene-based film. This corrugated morphology effectively mitigates the compact stacking of the sheets, causing more surface area be exposed to the electrolyte ions. Electrochemical measurements show that a flexible film supercapacitor using such corrugated graphene-based films as the active electrodes shows large specific capacitances (127 mF cm−2, 107 F cm−3), ultrahigh volumetric energy density (14.8 Wh L−1 at 53.6 W L−1, 10.4 Wh L−1 at 1.134 kW L−1), and excellent capacitance retention, far exceeding that of many previously reported freestanding graphene-based film supercapacitors. The interlayer water molecules between GO sheets are utilized as the spacers during the transformation of GO to graphene, which leads to a freestanding graphene-based film with corrugated graphene sheets. The corrugated morphology mitigates the compact stacking of the sheets and endows the as-obtained film electrode with a large ion accessible surface and superior electrochemical properties. This work hints that interlayer water molecules should be excellent spacers to address the serious stacking problem of graphene sheets in the fabrication of graphene-based electrode materials from GO. [Display omitted]
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2020.01.019