Construction of high-performance nitrogen-doped graphene quantum Dots@Carbon cloth-based electrode materials via cyclic voltammetry activation

Nitrogen-doped graphene quantum dots (N-GQDs) have gained significant attention in supercapacitors (SCs) for their excellent conductivity, high surface area, and abundant active sites. Here, N-GQDs@activated carbon cloth composite electrode (N-GQDs@ACC) has been constructed by electrochemical deposition and cyclic voltammetry (CV) activation using carbon cloth as the current collector, where CV activation can significantly improve the distribution of N-GQDs on the ACC surface. After 2000 cycles of CV activation, N-GQDs are uniformly distributed on the surface of ACC. The activation mechanism is summarized based on structural and compositional changes during CV activation, and the differences of electrochemical performance under different CV activation conditions are analyzed. The results show that the N-GQDs@ACC-4 electrode exhibits excellent energy storage capabilities with an area specific capacitance of 1191.67 mF cm- 2 at 1 mA cm- 2 (2775.15 F g-1 at 1.5 A g- 1), which is 7.76 times that of the unactivated electrode. Additionally, the N-GQDs@ACC-4 electrode demonstrates outstanding rate performance and cycling stability (99.8 % capacitance retention after 10,000 cycles). The assembled flexible device exhibits high energy density (50.69 mu Wh cm- 2 at 500 mu W cm- 2), stable output voltage, excellent bending stability, and good low-temperature performance. This work focuses on analyzing the evolution of the microstructure or composition of N-GQDs@ACC under CV activation and shows great application prospects of N-GQDs-based electrode material in advanced flexible SCs.