Ionic liquid induced electrostatic self-assemble of reduced graphene oxide for high-performance all-solid-state flexible symmetric supercapacitor

Flexible solid-state supercapacitors are arousing tremendous research enthusiasm in modern wearable and portable electronic equipment. Fabricating flexible electrode materials turns out to be a key challenge. Here, we developed a facile ionic liquid induced electrostatic self-assemble method to prepare bendable reduced graphene oxide (ILG). Due to electrostatic interaction between ionic liquid and graphene oxide, the ionic liquid can effectively prevent the aggregation of GO layers and protect partial O-containing functional groups at the same time. The IL plays great roles of a protector and stabilizer. The obtained ILG shows high specific capacitance (260 F g−1 at 0.5 A g−1), superior rate capability (62% from 0.5 to 100 A g−1) and outstanding energy density (9.03 W h kg−1 at 125 W kg−1) in 6 M KOH electrolyte. The constructed flexible symmetric all-solid-state supercapacitor also exhibits a specific capacitance of 195 F g−1 at 0.5 A g−1 and approximately 100% capacitance retention at different bending angels. The one-step approach might provide us with a new avenue for designing other flexible materials used in bendable devices. [Display omitted] •A simple method to prepare material with one-step ionothermal assistance.•Use of electrostatic self-assembly induced by IL ([Bmim]Cl).•A green process without the adding of binder and conductive agent.•Assemble all-solid-state supercapacitor with good flexibility.