Tuning the electrochemical properties of carbon-based supercapacitors by composite preparation and cell asymmetries

Abstract

The development of faster, safer and higher performance solid-state energy storage devices has motivated scientists to explore various strategies to obtain more efficient systems. In this work we evaluated the influence of different carbon material electrodes with a gel polymer electrolyte on the electrochemical properties of solid-state supercapacitors. The gel polymer electrolyte exhibited remarkable adhesive characteristics which allowed a good adherability and wettability of the gel electrolyte on the surfaces of all electrodes tested. Four types of supercapacitors were prepared and the influence of different types of electrodes and their combinations on the properties of supercapacitor was evaluated using electrochemical impedance spectroscopy, cyclic voltammetry and the galvanostatic charge/discharge technique that allows synchronous measurements of the cell voltage and the potential of the positive and negative electrodes. The asymmetric device with rGO (reduced graphene oxide) working on the negative electrode and f-MWCNT (acid functionalized multiwalled carbon nanotubes) on the positive electrode showed the best retention capacity for all studied properties (capacitance, energy density and power) after 2000 charge and discharge cycles. Flexible supercapacitor was also prepared, and various electrochemical parameters of the device were studied as a function of bending. We do not observe significant changes in its electrochemical properties after bending.