Influence of aqueous electrolytes on electrochemical performance of vertical graphene nanosheets supercapacitor electrode

TL;DR

This study investigates how different aqueous electrolytes affect the electrochemical performance of vertical graphene nanosheets used as supercapacitor electrodes, highlighting H2SO4's superior performance and stability.

Contribution

It demonstrates the influence of various aqueous electrolytes on VGN supercapacitors and identifies H2SO4 as the most effective electrolyte for enhanced capacitance and stability.

Findings

H2SO4 electrolyte yields highest specific capacitance

Capacitance retention remains above 96% after 200 cycles

Impedance spectra show minimal change across electrolytes

Abstract

Vertical graphene nanosheets (VGN) grown as controlled porous network are studied and demonstrated as a promising electrode material for supercapacitors. The VGN synthesized by microwave plasma enhanced chemical vapor deposition using CH4/Ar gas mixture as precursor are considered for electrochemical performance in Na2SO4, KOH, and H2SO4 to delineate the electrolyte effect. Among the electrolytes, H2SO4 exhibited excellent specific areal capacitance (188 microfarad/cm2) and good capacitance retention (96.8%). No significant change is observed in impedance spectra even after 200 cycles. An electric equivalent circuit for the system is simulated from Nyquist plot to elucidate the behavior of electrode/electrolyte interface. This potential supercapacitor electrode material is well characterized by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and contact angle measurement. Utilization of aqueous electrolytes for potential supercapacitors is also discussed in relation to improved performance observed in H2SO4 medium.