Synthesis of porous graphene/activated carbon composite with high packing density and large specific surface area for supercapacitor electrode material

A simple method has been developed to prepare graphene/activated carbon (AC) nanosheet composite as high-performance electrode material for supercapacitor . Glucose solution containing dispersed graphite oxide (GO) sheets is hydrothermally carbonized to form a brown char-like intermediate product, and finally converts to porous nanosheet composite by two-step chemical activation using KOH. In this composite, a layer of porous AC coats on graphene to from wrinkled nanosheet structure, with length of several micrometers and thickness of tens of nanometer . The composite has a relatively high packing density of ∼0.3 g cm −3 and large specific surface area of 2106 m 2 g −1 , as well as containing plenty of mesopores . It exhibits specific capacitance up to 210 F g −1 in aqueous electrolyte and 103 F g −1 in organic electrolyte, respectively, and the specific capacitance decreases by only 5.3% after 5000 cycles. These results indicate that the porous graphene/AC nanosheet composite prepared by hydrothermal carbonization and chemical activation can be applied for high performance supercapacitors .