Nitrogen-Doped Carbon Derived from Deep Eutectic Solvent as a High-Performance Supercapacitor

As a kind of ionic fluid, deep-eutectic solvent (DES) has been used not only as a solvent but also as a precursor for carbon preparation in recent years. Herein, porous nitrogen-doped carbon (NC) has been prepared via simple pyrolysis of l-tyrosine-based DES. The effects of the proportion of the components in DES and the carbonization temperature on the morphology, pore structure, chemical composition, and the performance for supercapacitor application have been investigated. The as-prepared NCs show large surface areas, high nitrogen contents, hierarchical porous structures, and excellent capacitive performances. Specifically, the optimized sample exhibits a higher specific capacitance (306.5 F g–1), better rate capability (70.3% at 50 A g–1), and also shows high area capacitance (7.1 F cm–2) and specific capacitance (235.8 F g–1) when 30 mg/cm2 of the sample is loaded. The constructed symmetric supercapacitor attains a high energy density of 16.9 W h kg–1 (at 450 W kg–1) in the neutral electrolyte and outstanding cycling stability of 100% retention after 50,000 cycles. Moreover, the fabricated symmetrical solid KOH/poly(vinyl alcohol) supercapacitor displays a superior energy density of 15.2 W h kg–1 at 700 W kg–1 and can retain 8.8 W h kg–1 at 14 kW kg–1. Our work presents a route for the synthesis of porous carbon using DES as the carbonaceous precursor and also demonstrates its possible application in energy storage.