Charge Storage Properties of Aqueous Halide Supercapatteries with Activated Carbon and Graphene Nanoplatelets as Active Electrode Materials

Bamidele Akinwolemiwa,George Z Chen,Qinghua Yang,Chaohui Wei

doi:10.1002/eem2.12133

Abstract

Device level performance of aqueous halide supercapatteries fabricated with equal electrode mass of activated carbon or graphene nanoplatelets has been characterized. It was revealed that the surface oxygen groups in the graphitic structures of the nanoplatelets contributed toward a more enhanced charge storage capacity in bromide containing redox electrolytes. Moreover, the rate performance of the devices could be linked to the effect of the pore size of the carbons on the dynamics of the inactive alkali metal counterion of the redox halide salt. Additionally, the charge storage performance of aqueous halide supercapatteries with graphene nanoplatelets as the electrode material may be attributed to the combined effect of the porous structure on the dynamics of the non‐active cations and a possible interaction of the Br−/(Br2 + Br3−) redox triple with the surface oxygen groups within the graphitic layer of the nanoplatelets. Generally, it has been shown that the surface groups and microstructure of electrode materials must be critically correlated with the redox electrolytes in the ongoing efforts to commercialize these devices.

Highlights

In principle, improving the electrode capacitance and operating potential window of the electrode |electrolyte (E|E) interface is a general strategy to obtain high energy supercapacitors and supercapacitor-battery hybrids, i.e. supercapatteries
Therein, we demonstrated that the electrode potential of the Br−/(Br2 + Br3−) redox triple resulted in improved device charge capacity through a combined double layer and Nernstian storage mechanism[9]
Indicates AC-2 to be microporous as can be seen from its isotherms which are characterised by a high volume of adsorption at relatively low pressures 22

Summary

Introduction

In principle, improving the electrode capacitance and operating potential window of the electrode |. Along these lines, it has been described that for inert electrolytes, the porous volume of the electrode acts as a “dead-volume”. This was done by correlating the porous and surface physicochemical characteristics of these electrodes with the properties of the redox electrolytes such as the concentration and hydrous sizes of the active bromide and dissolved cations, respectively

Experimental

Properties of the activated carbon and graphene nanoplatelets

Conclusions