High performance coin-cell and pouch-cell supercapacitors based on nitrogen-doped reduced graphene oxide electrodes with phenylenediamine-mediated organic electrolyte

Coin-cell (CR2023) and pouch-cell supercapacitors (SC) with high specific energy were fabricated using nitrogen-doped reduced graphene oxide (x-N-rGO) as active electrodes and para-phenylenediamine (PPD) in 1 M tetraethyl ammonium tetra-fluoroborate (TEABF(4)) in acetonitrile as a redox-media organic electrolyte. x-N-rGO with different contents of N-functional groups were synthesized through a hydrothermal reduction of graphene oxide using different concentrations of NH4OH. Electrochemical measurement results suggested that x-N-rGO could provide the enhancements of electrical double layer charge storage as well as redox charge capacity due to its high surface area and redox properties of x-N-rGO. To further improve specific capacitance and specific energy, PPD was introduced into 1 M TEABF(4)/ACN to amplify the redox reaction rate. The specific capacitance and specific energy significantly enhanced with increasing N content of x-N-rGO because N-functional groups can interact with PPD in electrolyte, resulting in an enhanced redox reaction rate as indicated by the occurrence of redox peaks in cyclic voltammograms. The coin-cell and pouch-cell SCs using 20-N-rGO with 0.2M PPD + 1 M TEABF(4)/ACN exhibited the high specific capacitance of 563 and 340 F g(-1) with high energy density 149.4 and 77.2 Wh.kg(-1) at 1 A g(-1), respectively. Hence, they could be a promising alternative for advanced energy storage applications.