In recent years, portable and wearable electronic devices have developed by leaps and bounds. In order to make wearable electronic devices more flexible, lightweight, intelligent and fully productized, it is necessary to further explore the matching of thin, light and flexible energy storage. Supercapacitors have attracted wide attention from researchers due to their high power density, long cycle life, high mechanical strength, high safety and ease of assembly. However, once the traditional supercapacitor is deformed by external force, the energy storage characteristics will be greatly reduced or even lost. The electrode material is the core of the capacitor, so it is necessary to develop an electrode material with high flexibility and superior energy storage characteristics. Graphene has a large specific surface area, excellent mechanical and electrical properties and has become an attractive electrode material for flexible supercapacitors. Pseudocapacitance materials can provide high specific capacitance, but have the poor conductivity and low stability. Researchers will use graphene and pseudocapacitance materials are used as electrode materials to fully utilize their respective advantages, which not only overcomes the shortcomings of easy agglomeration between graphene sheets, but also improves the overall energy density of flexible supercapacitors. Since the two-dimensional graphene sheets are easy to stack and the electron conductivity is limited, more research work is currently devoted to the three-dimensional porous network structure of graphene materials. This paper highlights two important roles of graphene: (1) composite with electrochemically active materials as active materials; (2) as the conductive and flexible substrate for depositing active materials, so functionally diverse graphene has great potential in the preparation of flexible electrodes. Graphene with high conductivity was directly used as a flexible substrate by chemical deposition, dip coating, hydrothermal and other processes, or it was bonded with pseudocapacitance material and attached to the flexible matrix to prepare graphene-based flexible electrode materials. This paper introduces the energy storage principle of supercapacitors and the application of graphene in flexible supercapacitors, and summarizes the research progress of graphene/transition metal oxide and graphene/conductive polymer composite electrode materials in flexible supercapacitors; flexible supercapacitor electrode materials still face challenges and prospects for future development. © 2020, Materials Review Magazine. All right reserved.
