Template‐assisted synthesis of nitrogen‐doped porous carbon derived from bean dregs for high‐performance supercapacitor

Abstract Porous carbon is the commonly used electrode material for supercapacitor, and its electrochemical performance is affected by the factors such as specific surface area (SSA), pore structure, heteroatomic content, and resistivity. In this paper, bean dregs‐based porous carbon (BDPC) was synthesized with bean dregs as the carbon and nitrogen sources and magnesium citrate as template. The electrochemical properties of BDPC were investigated in 6 M KOH electrolyte. It is found that BDPC presents a well‐developed mesoporous structure and BDPC‐20 owns the highest SSA of 1637 m 2 /g. The nitrogen content decreases significantly with the heating rate, debilitating the hydrophilicity of BDPC. High heating rate can increase the relative content of graphitic‐N and the degree of graphitization and consequently reduces the resistivity of BDPC enormously. The BDPC‐20 shows the lowest resistivity of 97.2 μΩ·m. The cyclic voltammetry curves of BDPC electrodes exhibit the quasi‐rectangular shape, demonstrating a typical electrical double‐layer capacitor nature of energy storage. According to the galvanostatic charge–discharge measurement, BDPC‐10 possesses the largest specific capacitance of 184.0 F/g.