Hydrothermal preparation of cotton-based rGO/N-doped porous carbon as electrode materials of supercapacitors

Abstract

Porous carbon electrode materials are commonly used in supercapacitors due to their inexpensive raw materials, simple processing, and low pollution, aligning with the vision for green energy storage. Consequently, there is a current trend to discover porous carbon electrode materials with superior electrochemical properties. To enhance the pore volume ratio and electrochemical performance of porous carbon materials, this study proposes a hydrothermal method to pretreat the raw materials, facilitating the doping of nitrogen from urea. Moreover, graphene is introduced for its excellent conductivity, which can further improve the electrochemical properties of the material. We found a new one-step reduction Graphene Oxide (rGO)and the doping of nitrogen (N) elements were optimized by hydrothermal method, the wettability and pseudo-capacitance performance of the material are improved, and HTPC-700 shows a very excellent specific capacitance, its specific capacitance reaches 600 F g⁻¹ at a current density of 0.5 A g⁻¹, and it even reaches 260 F g⁻¹ at a current density of 1 A g⁻¹. Meanwhile the power density and energy density are respectively 74 W h kg⁻¹ and 280 W kg⁻¹. It also exhibits a remarkable capacitance retention rate of over 98.7 % after 5000 cycles at a current density of 1 A g⁻¹. Additionally, it demonstrates a rich ant nest-like pore structure and good specific surface area of 2427 m²/g, and a large pore volume of 1.09 cm³/g after carbonization and KOH activation. This study offers a novel doping method and provides a unique perspective for the development of porous carbon electrodes.