Azide-assisted hydrothermal synthesis of N-doped mesoporous carbon cloth for high-performance symmetric supercapacitor employing LiClO4 as electrolyte

In our investigation, N-doped porous carbon cloth (NPCC) was synthesized through KOH activation and sodium azide-assisted hydrothermal method to improve its surface area and conductivity, respectively. The morphology and structure of the obtained NPCC were investigated by X-ray photoelectron spectroscopy (XPS), scanning electron microscopy, and high-resolution transmission electron microscopy. Cyclic voltammetry, galvanostatic charge/discharge test, and electrochemical impedance spectroscopy were then performed to test electrochemical performance of the NPCC. The surface area of the NPCC was approximately 52 m2 g−1, which was 6.5 times higher than that of carbon cloth (CC, 8 m2 g−1), and the average pore size of NPCC was 5.0 nm. XPS demonstrated that elemental N (pyrrolic N and quaternary N) was successfully doped into the CC structure with a total N content of 3.49%. Electrochemical assessment was conducted in a symmetrical system in 1 M LiClO4/acetonitrile electrolyte. The charge transfer resistance was significantly decreased from 97 Ω to 60 Ω after N-doping treatment. The NPCC device delivered a high areal capacitance of 130 mF cm−2 at a current density of 1 mA cm−2, and the highest volumetric energy density of 2.03 mW h cm−3 (16.25 W h kg−1) was achieved at a volumetric power density of 0.375 W cm−3 (3 kW kg−1). Additionally, the device could retain 95.8% of its initial capacitance even after 30,000 cycles.