Anthracene-Functionalized Carbon Dots for High-Performance All-Organic Symmetric Supercapacitors

Considering the space constraints, improving energy density in a restricted area or volume is crucial for developing viable, lightweight energy-storage devices. Herein, an all-organic electrode (PCA) is developed by covalently functionalizing carbon dots with redox-active 9-anthraldehyde and using poly(vinyl alcohol) as the binder, enabling a strong diffusion-limited charge storage process. The as-prepared electrode with anthraldehyde coated on graphite foil delivers an areal capacitance of 143 mF cm–2 (200 F g–1) at 5 mV s–1, which is significantly higher than that of the electrode without anthraldehyde, attributed entirely to the diffusion-limited charge storage process. The as-prepared symmetric supercapacitor with low active mass loading (2.2 mg cm–2) facilitates enhanced electrolyte diffusion, lower series resistance, and higher energy efficiency, delivering a high energy density of 8.3 mWh cm–2 and a peak power density of 1560 mW cm–2 with capacitance retention of 78% over 10,000 GCD cycles with an energy efficiency of 98%. Further, the device’s volume allows it to produce an exceptional energy density of 553.5 mWh cm–3 and a peak power density of 104 W cm–3, outperforming many organic- and inorganic-based supercapacitors.