The Effect of Different Gel Electrolytes on Graphene Based Solid-State Supercapacitors （oral)

Graphene is a good candidate for the electrode materials for supercapacitors, as it’s excellent electrical, mechanical and optical properties. A  all  solid-state supercapacitors based on graphene was designed to study the effect of different electrically conductive substance (H₃PO₄, H₂SO₄, KOH, NaOH, KCl, NaCl) in polymer polyethylene terephthalate (PVA) gel electrolytes on the electrochemical performance of this supercapacitor,

Large multilayer graphene films were grown on copper foils by chemical vapor deposition (CVD) method. The few-layer graphene film grown by chemical vapor deposition was cut into squares with sides of 7~10 centimeters and was transferred onto the PET substrate directly. This supercapacitor is easily assembled through binding the two graphene electrodes together by gel electrolyte. Thus the device simply contains two film electrodes separated by solid electrolyte (gel electrolyte solidifies by water loss) and two flexible substrates, so it is ultrathin and high flexible.

The experiment demonstrated the specific capacitance of this graphene based solid-state supercapacitors varies with different electrically conductive substance in gel electrolytes with tremendous dissimilar cyclic voltammetry curves. The supercapacitors used PVA-H₂SO₄ electrolyte show higher device specific capacitance of 0.82mF/cm² at a scanning rate of 100mV/s than other electrolyte. By optimization the concentration of H₃PO₄ from 0.01mol to 0.09mol in equal amount of PVA gel, the device specific capacitance of this supercapacitors was elevated from 0.07mF/cm² to 2.64mF/cm². At the same time the internal resistance decreased with the adding of H₃PO_4. The graphene-based supercapacitors provided imponderable changes of electrochemical properties during bend to 180-degree. This supercapacitors also possess great stability after 5000 circulations with more than 92% specific capacitance retained.