Poly(ionic liquid)-assisted reduction of graphene oxide to achieve high-performance composite electrodes

In this work, GO was solvothermally reduced in the presence of imidazolium-based poly(ionic liquid) (PIL) of poly(1-butyl-3-vinylimidazolium hexafluorophosphate) to produce a PIL-modified reduced GO (PIL-rGO) composite. The integration of PILs with rGO is capable of preventing the restacking of rGO sheets, and hence, providing a large electrolyte ion-accessible surface and an abundant interior space for charge storage by enlarging the interlayer spacing in PIL-rGO. The PIL-rGO composite was then used as the supercapacitor electrode associated with a compatible IL of 1-butyl-3-methylimidazolium hexafluorophosphate as the electrolyte. The PIL herein improves the interface wettability between the electrode and electrolyte, and the IL electrolyte enables a wide potential window as well. Specific capacitances correspond to 196 F/g at a current density of 1 A/g, 160 F/g at 2 A/g, and 144.8 F/g at a scan rate of 60 mV/s, which are much higher than those (104 F/g at 2 A/g, and 48.1 F/g at 60 mV/s) of pure rGO. The capacitance retention is as high as 80.7% after 1000 charge-discharge cycles at a discharge current density of 2 A/g. The interfacial charge-transfer resistance of the PIL-rGO electrode (4.6 Ω) is also much lower than that of the rGO electrode (18.7 Ω). Such graphene-base electrodes may promise a candidate for high performance supercapacitors.