Abstract
The scientific focus has been directed through the production and application of “wonder material-graphene” after its discovery in 2004. But the mass production cost has become a huge disadvantage towards commercializing graphene-based manufactures. As alternative low-cost material, exfoliated graphite (EG) has emerged to be a novel nanostructured carbon material with a potential for electrochemical energy storage device applications owed to its unique characteristics similar to graphene. In this study a series of EG samples were prepared by a surfactant-mediated liquid-phase exfoliation method by changing the exfoliation time. Electrochemical double-layer capacitors (EDLCs) were fabricated using different EG samples as an electrode material and a gel polymer electrolyte (GPE). They were characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic charge discharge (GCD) techniques. EDLC having EG electrodes of 10 h exfoliation time showed the highest results with single-electrode specific capacitance (Csc) of 4.12 F g−1, single-electrode specific discharge capacitance (Csd) of 1.10 F g−1, and relaxation time of 0.22 s from CV, GCD, and EIS, respectively.
Highlights
Exfoliated graphite (EG) denotes to graphite which has a degree of separation of carbon layers in the graphite
In one of our previous studies, we have found that the potential window within which the Electrochemical double layer capacitors (EDLCs) could operate without any distortion was as -1.0 to 1.0 V [14]
Preparation of exfoliated graphite (EG) electrodes In the exfoliation process, when graphite powder is mixed in aqueous sodium dodecylbenzenesulfonate (SDBS) solution, a graphitic collidal suspension is formed
Summary
Exfoliated graphite (EG) denotes to graphite which has a degree of separation of carbon layers in the graphite. Nawaz et al evaluated the effect of concentration of sodium cholate (SC) on the exfoliation of graphite in aqueous media [6] These surfactants are used as intercalating agents and as stabilizers to prevent EG from restacking in the solution. Properties of EG will vary upon its synthesis method Variables such as, exfoliation time, surfactant type, surfactant concentration and solvent will affect on the physical and chemical characteristics of EG. This study mainly focuses on the surfactant mediated liquid phase exfoliation of Sri Lankan natural graphite and to use the resulting EG as an electrode material in an EDLC with a GPE while giving an estimation on the capacitance of the EG based EDLCs through a viewpoint of exfoliation time. Several EDLCs were fabricated using electrodes prepared with different exfoliation time
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