Constructing molecules supported holey graphene sheets framework in compact graphene film to achieve synergistic effect for ion transport and high gravimetric/volumetric capacitances

Abstract Boosting the utilization rate of graphene sheets in compact graphene film is essential to realize high-density energy storage for graphene film based supercapacitors. Here, a p-phenylenediamine (PPDA) molecules supporting holey graphene sheets framework is built in graphene film (PPDA-HGF). In PPDA-HGF, the nanopores across the basal plane of graphene sheets promote ion access to graphene sheet surface, the PPDA molecular “supports” between graphene layers create uniformly expanding interlayer spacing (~1.2 nm), which is beneficial for ion transport between layers. So, the open framework contributes to synergistic effect for ion access and transport in PPDA-HGF. With abundant ion-accessible transport channels, good wettability (42°) and high conductivity (3927 S m−1), PPDA-HGF exhibits significant improvement of electrochemical performance comparing to counterparts and delivers a gravimetric capacitance of 300 F g−1 and a volumetric capacitance of 516 F cm−3, excellent rate capability (78.3% capacitance retention from 0.5 to 100 A g−1), and superior cycling stability. Furthermore, the flexible solid-state supercapacitor based on PPDA-HGFs delivers comparable volumetric energy density of 2.7 Wh L−1 to 4 V/500 μAh Li thin-film batteries and practicably mechanical flexibility. This work opens up a structural cooperation strategy to achieve synergistic effect for ion access and transport in compact graphene film.