Recent advances and perspectives on graphene-based gels for superior flexible all-solid-state supercapacitors

As a new generation of energy storage and power supply devices, flexible all-solid-state supercapacitors (FASSS) have drawn extensive concern owing to their high power density, good flexibility, light weight, small size, good safety and long cycle life. The electrode and electrolyte materials of FASSS have important influences on the electrochemical properties of supercapacitors, they have been widely studied and reported in recent years. Graphene-based gel with 3D network structure is a novel material, which combines the physicochemical properties of graphene and the structural properties of gel. The application of graphene-based gel in flexible/stretchable FASSS can not only improve the electrochemical performance but also impart various functional properties to FASSS such as self-healing, high cold resistance and so on. This paper systematically introduces the preparation strategies and structural regulation methods of graphene-based gels, and summarizes the application research progress of graphene-based gel composites in electrode and electrolyte materials of FASSS in recent years. The effect mechanism of functionalized graphene-based gels on the electrochemical properties, mechanical properties and various functional properties such as self-healing and high cold resistance are discussed. Finally, the prospects and challenges of graphene-based gels in FASSS are analyzed, which can provide ideas for development of new FASSS.