Graphene integrating carbon fiber and hierarchical porous carbon formed robust flexible “carbon-concrete” supercapacitor film

All carbon-electrode is ideal for supercapacitor, but synthesizing macro-level >3 GPa strong porous carbon electrode is challenging. Here, we presented an approach of synthesizing robust flexible “carbon-concrete” films integrating carbon fibers, graphene and hierarchical porous activated carbon. The method involved electrochemically spreading of carbon fiber bundles and in-situ activation of cellulose coating layers. It was found that 10–30 μm large literal size of electrochemically exfoliated graphene flakes could play a key role in in-situ fixing individual carbon fiber layer and protecting carbon fibers from activation corrosion. The new flexible porous “carbon-concrete” film with 40 μm thickness exhibited 5.3 GPa mechanical strength, specific area of 830 m2/g and broad pore size distribution. This light carbon material could be potentially used for integrating supercapacitor energy storage with automobiles.