Effect of binder on electrochemical properties of graphene nanoplatelets coated carbon fiber structural supercapacitors

Effect of binder on electrochemical properties of graphene nanoplatelets coated carbon fiber structural supercapacitors

The structural supercapacitor is a multifunctional device which provides mechanical load bearing and electrochemical energy storage functionalities simultaneously. A structural supercapacitor (single-cell configuration) comprises two carbon fiber (CF) electrodes that sandwich an electrically insulating separator with a structural electrolyte. Pristine CF electrodes are unable to deliver the expected electrochemical performances because of chemical inertness and limited active-surface area. To address this issue, the surface modifications of CFs have been identified as a promising solution. The deposition of electrochemically active materials with a large specific surface area can substantially improve the electrochemical properties. Particularly, graphene nanoplatelets (GNPs) are being widely explored as an active material for coating on CF surfaces. In this study, we investigated the influence of polytetrafluoroethylene (PTFE) binder for having a stable GNP coating on the CF surface and its effect on the performance of structural supercapacitor. PTFE is regarded as one of the best binders for supercapacitors due to its excellent electrochemical performance, including high specific capacitance, stability, and rate capability. The electrochemical performance of the structural supercapacitor was evaluated through cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) techniques. The performance of structural supercapacitors based on GNP coating with PTFE binder was systematically compared to that of a GNP coating without a binder. The structural supercapacitor based on GNP coated with PTFE binder exhibited a specific capacitance of 35.1 mF/cm2 at the scanning rate of 5 mV/s and 86% of its capacity was retained after 1000 charge-discharge cycles. Structural supercapacitor based on GNP coated without PTFE binder exhibited a specific capacitance of 39.1 mF/cm2 at the scanning rate of 5 mV/s and 65% of its capacity was retained after 1000 charge-discharge cycles. The capacitance retention of the structural supercapacitor with GNP coated without PTFE binder showed a 21% reduction compared to the structural supercapacitor with GNP coated with PTFE binder. Therefore, the use of 0.6% PTFE binder is suitable for having a stable and durable GNP coating on the carbon fiber electrode and develop a structural supercapacitor with a high cycle life.

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This article is part of a UniSQ Thesis by publication. See Related Output.