Graphene-Ionic Liquids Supercapacitors: Design, Fabrication and Applications

Supercapacitors (SCs) based on graphene electrode and ionic liquids (ILs) as electrolytes hold great promise owing to their high operation voltage and energy density. Due to the great variety of cations and anions in ILs, the influence of the composition of ILs on the electrochemical characteristics and storage mechanism of graphene-ILs SCs are demonstrated. The principles and methods of matching between graphene electrode and ILs electrolytes are highlighted through a comprehensive analysis of the literature. Afterwards, the progress made so far for the research of graphene-ILs SCs is critically reviewed, with the main focus on the preparation of graphene with various reasonable structures, as well as the hybridization of graphene with other electro-active materials for achieving better electrochemical performance in ILs electrolytes. Additionally, we review recent achievements in the design and fabrication of flexible graphene-ILs SCs, and their application in portable electronics. Moreover, some of the latest achievements regarding interesting graphene-ILs micro-SCs are also reviewed. At last, we discuss the challenges for future research development and present our perspectives. We expect to stimulate more research in creating graphene- ILs SCs for wide practical applications.