Cotton Candy-Inspired Porous Activated Carbon via Molten Salt-Shielded Synthesis in Air and Its Application in Supercapacitors

Owing to the inherent complexity and difficulty in characterizing nanoporous carbon electrodes, establishing clear design strategies for enhanced supercapacitors remains a challenge. Inspired by the fabrication of cotton candy from sucrose, we produced a unique porous carbon consisting of self-assembled nanoparticles. The carbon precursor was prepared by centrifuging a sucrose solution using a cotton candy machine. Subsequently, a low-melting point eutectic salt mixture (ZnCl2/KCl) was employed as a shield to synthesize cotton candy-derived activated carbon (CAC) directly under an air atmosphere via low-temperature carbonization. The as-obtained CAC possesses both a large specific surface area of 1976 m2 g-1 and a high oxygen content of 7.89 atom %, which can provide sufficient active sites and introduce pseudocapacitance, respectively. In addition, the disorder of carbons has been correlated with capacitance and Raman spectroscopy revealed that carbons with increased disorder, thus, exhibited enhanced capacitance. The designed CAC electrode demonstrates a high specific capacitance of 338 F g-1 at a current density of 1 A g-1, along with promising cycling stability (94.4% retention) after 20 000 cycles. Additionally, the CAC//CAC symmetric supercapacitor reaches energy densities of 20.3 W h kg-1, exhibits good cycling stability, and retains 94.6% of the initial capacitance after 20 000 cycles (2 A g-1). Our findings provide a pathway for manipulating the disorder of the carbon electrodes to develop high-energy density supercapacitors.