摘要
Supercapacitors formed from porous carbon and graphene-oxide(GO)materials are usually dominated by either electric double-layer capacitance,pseudo-capacitance,or both.Due to these combined features,reduced GO materials have been shown to offer superior capacitance over typical nanoporous carbon materials;however,there is a significant variation in reported values,ranging between 25 and 350 F g^(−1).This undermines the structure(e.g.,oxygen functionality and/or surface area)-performance relationships for optimization of cost and scalable factors.This work demonstrates important structure-controlled charge storage relationships.For this,a series of exfoliated graphene(EG)derivatives are produced via thermal-shock exfoliation of GO precursors and following controlled graphitization of EG(GEG)generates materials with varied amounts of porosity,redox-active oxygen groups and graphitic components.Experimental results show significantly varied capacitance values between 30 and 250 F g^(−1)at 1.0 A g^(−1)in GEG structures;this suggests that for a given specific surface area the redox-active and hydrophilic oxygen content can boost the capacitance to 250–300%higher compared to typical mesoporous carbon materials.GEGs with identical oxygen functionality show a surface area governed capacitance.This allows to establish direct structure-performance relationships between 1)redox-active oxygen functional concentration and capacitance and 2)surface area and capacitance.
基金
supported by EPSRC(grants of EP/R511638/1,EP/S018204/2,EP/R023581/1,EP/W03395X/1,EP/W033321/1)
the Science Specialty Program of Sichuan University(Grant.No.2020SCUNL210)
The Royal Academy of Engineering is acknowledged for the financial support of Shearing(Ci ET171859)
Brett(RCSRF2021/13/53)under the Research Chairs and Senior Research Fel owships scheme
the National Physical Laboratory(NPL)and HORIBA MIRA for the support of his RAEng Research Chair
作者简介
Srinivas Gadipelli,E-mail:s.gadipelli@ucl.ac.uk;Dan J.L.Brett,E-mail:d.brett@ucl.ac.uk
