Preparation of Biomass-Based Porous Carbons with High Specific Capacitance for Applications in Supercapacitors

Supercapacitors are developing in terms of high power and energy densities. Carbon materials can meet this challenge to a certain extent. A sustainable high-performance carbon material for supercapacitors was prepared through the simple and green thermal pyrolysis of orange peels as raw materials by using KOH as an activator. The biomass-derived carbon materials activated at different temperatures were evaluated as electrode materials. The adsorption properties, structure, and surface elemental chemical states of the prepared materials were studied. Carbonation temperature plays a key role in the preparation of materials, and it has different effects on the physical and electrochemical properties of materials. The opc700 and opc800 samples have large pore volumes, which provide the necessary space for the storage of electrolyte ions. The temperature has a pronounced effect on the specific surface area and the electrochemical performance. The specific surface area of opc800 is as high as 2004 m² g⁻¹ and the pore volume is 1.24 cm³ g⁻¹. The maximum specific capacity of opc800 is 306.6 F g⁻¹ at 0.5 A g⁻¹ and the specific capacitance is 251.2 F g⁻¹ at 20 A g⁻¹.