A flexible composite film electrode and supercapacitor based on combined effect between graphene oxide and graphene

Graphene film has drawn great attention in flexible supercapacitors for its large specific surface area and high conductivity, but the trade-off between capacitance (positively correlated with structural defects) and electrical conductivity (negatively correlated with structural defects) still hinder its application. Herein, a graphene-based composite film is fabricated by cooperating graphene oxide with highly conductive graphene flakes. With the combined effect, graphene flakes endow the composite films with high electrical conductivity, while graphene oxide provides extra pseudocapacitance. The composite film shows a high specific capacitance of 191.1 F g−1, which is far beyond that of pure graphene film (6.7 F g−1). The assembled flexible supercapacitor shows no capacitance decline when bent at different angles, and the capacitance retention of the supercapacitor keeps at 55.8% after 4500 bending-releasing cycles (0–180°). The excellent mechanical and electrochemical performance of reduced graphene oxide/graphene composite film makes it a promising candidate in flexible supercapacitors.