Hierarchically structured graphene-based supercapacitor electrodes

The performance of supercapacitor electrodes is determined largely by their components and structure. Graphene has revealed the intriguing potential in developing high performance electrodes. To optimize the electrochemical properties, hierarchically structured graphene networks have been utilized to prepare the electrode of supercapacitors and exhibited the specific surface area larger than the theoretical value and the specific capacitance close to the maximum of single-layer graphene nanosheets. When graphene is combined with other high capacitance components such as nanostructured metal oxide and conductive polymers, the hierarchical composite electrodes exhibited a large development space for high performance supercapacitors. Herein, we review their recent advances and discuss the effect of molecular structures (oxygen functionalities, heteroatom doping), deposited metal oxide and conductive polymer nanoparticles on the performance of hierarchically structured graphene supercapacitor electrodes.