Rapid Joule heating processing of nickel-based flexible supercapacitors

In this study, an ultrafast Joule heating method is employed to efficiently synthesize nickel sulfide and nickel oxide nanoparticles on buckypaper (Ni 3 S 2 -NiO@BP) as high-performance supercapacitor electrode materials. The thermal shock effect was tuned by adjusting the temperature of Joule heat through voltage regulation. The resulting composite material exhibits battery-like energy storage kinetics, boasting a specific capacity of 2278F g −1 at a current density of 1 A g −1 . Ex-situ X-ray diffraction and Raman spectroscopy measurements showed that Ni 3 S 2 -NiO gradually transforms into Ni(OH) 2 during cycling, and then to highly reactive NiOOH. Density functional theory (DFT) calculations confirm the enhanced conductivity and OH − adsorption of the heterogeneous structures. Furthermore, flexible hybrid asymmetric supercapacitors assembled from these electrodes exhibit a high energy density of 71.55 Wh kg −1 with a power density of 1124.8 W kg −1 , and stable electrochemical performance even under varying bending angles. The efficient synthesis approach presented here offers new insights into the rational design and engineering of electrode materials for high-performance, flexible supercapacitors.