At present, the energy storage performances of fiber supercapacitors are significantly limited by the insufficient charge transfer and defective loading of active materials. Here, to modify the rate capability and cycling stability of flexible fiber supercapacitors, a composite fiber with a hierarchical core-sheath structure is designed by first growing N-CNTs on a highly aligned CNT fiber and then depositing PANI on the N-CNTs. The primary core, highly aligned CNT fiber, ensures free-standing flexibility and the rapid transfer of electrons. The porous primary sheath and secondary core, N-CNTs, can form a framework so as to improve the loading mass and uniformity of the secondary sheath, PANI with high specific capacitance, and enhance the interaction between PANI and the N-CNTs. Moreover, the porous N-CNT structure can simultaneously greatly facilitate the transfer of electrons and ions. The synergistic effects of the CNT fiber, N-CNTs and PANI endow this hierarchical core-sheath structured PANI/N-CNT@CNT fiber with high specific capacitance, excellent rate capability and cycling stability. The specific capacitance reaches 323.8 F g⁻¹ at a current density of 1 A g⁻¹ and 221.3 F g⁻¹ can be retained at a high current density of 50 A g⁻¹. The assembled supercapacitor can maintain 92.1% of the original capacitance after 10 000 charge–discharge cycles at 20 A g⁻¹. Beyond excellent energy storage properties, it also exhibits excellent wearability and flexibility. The capacitance can be maintained at 95.5% after repeated bending processes for up to 10 000 cycles. This work provides a new strategy to develop fiber electrodes for high-performance wearable devices.

Amine-functionalized graphene oxide nanosheets (D400-GOs and D2000-GOs) were prepared by linear poly(oxyalkylene)amines with two different molecular weights, 400 and 2000 (D400 and D2000), attached onto the surface of graphene oxides via the reactions of amines with alkylcarboxyle groups. By mixing the amine-functionalized graphene oxide nanosheets, the epoxy resins (EPs) and curing agent, the amine-functionalized graphene oxide nanosheets/EPs nanocomposites were subsequently fabricated. In these nanocomposites, the amine-functionalized graphene oxide nanosheets could covalently integrate into EPs matrices via the reactions between the amine groups of the chemically converted graphene oxide nanosheets and epoxy groups of EPs, thereby causing these graphene oxide nanosheets to become part of the heavily cross-linked network. The mechanical and thermal properties of these nanocomposites are investigated in detail. The effect of the molecular chain length of the grafted polymers on the properties of the chemically converted graphene oxide nanosheets/EPs nanocomposites are thoroughly discussed. This study provides a new route to design and develop chemically converted graphene oxide nanosheets/polymer nanocomposite materials by varying the chain length of polymers grafted onto the surface of graphene oxide nanosheets and then tuning the interphases between graphene oxide nanosheets and polymer matrices.

Hierarchically ordered mesoporous carbon/graphene (OMC/G) composites have been fabricated by means of a solvent-evaporation-induced self-assembly (EISA) method. The structures of these composites are characterized by X-ray diffraction, transmission electron microscopy, Raman spectroscopy and nitrogen adsorption–desorption at 77 K. These results indicate that OMC/G composites possess the hierarchically ordered hexagonal p6mm mesostructure with the lattice unit parameter and pore diameter close to 10 nm and 3 nm, respectively. The specific surface area of OMC/G composites after KOH activation is high up to 2109.2 m² g⁻¹, which is significantly greater than OMC after activation (1474.6 m² g⁻¹). Subsequently, the resulting OMC/G composites as supercapacitor electrode materials exhibit an outstanding capacitance as high as 329.5 F g⁻¹ in 6 M KOH electrolyte at a current density of 0.5 A g⁻¹, which is much higher than both OMC (234.2 F g⁻¹) and a sample made by mechanical mixing of OMC with graphene (217.7 F g⁻¹). In addition, the obtained OMC/G composites display good cyclic stability, and the final capacitance retention is approximately 96% after 5000 cycles. These ordered mesopores in the OMC/G composites are beneficial to the accessibility and rapid diffusion of the electrolyte, while graphene in OMC/G composites can also facilitate the transport of electrons during the processes of charging and discharging owing to its high conductivity, thereby leading to an excellent energy storage performance. The method demonstrated in this work would open up a new route to design and develop graphene-based architectures for supercapacitor applications.