N,P‐Codoped, Low‐Density, Amorphous Carbon Foam for High‐Performance Supercapacitors: Polymer‐Based Scalable Production at Low Cost

Abstract

Herein, a large‐scale production of low‐dense (1.7–2.0 mg cc−1) amorphous carbon foam (char) is demonstrated by simple combustion of an epoxy‐based intumescent composite followed by annealing in argon at 600–900 ºC. It is observed that a balance among physical, chemical, and structural characteristics results in highest electrochemical energy storage performance. For example, the char annealed at 700 ºC (ATA 700) has a specific surface area of 970.55 m2 g−1, a highest pore width diversity (1.87–212.26 nm), moderate sp2‐C and N,P heteroatom contents, highest graphitic‐N, and moderate C–P binding networks. These characteristics promote 1109.7 and 310.4 F g−1 specific capacitances in ATA 700 char with 1 m H2SO4 for three and two electrode cell configurations, respectively, at 0.1 A g−1 specific current. Importantly, the cell demonstrates 97.25% coulombic efficiency and 86.3% capacitance retention after 20 000 charge–discharge cycles (8 A g−1). A highest energy density of 43.1 Wh kg−1 and 20 kW kg−1 peak power density are attained. Such performances are attributed to the hierarchically distributed mesopores and micropores for efficient charge and mass transports along with suitable heteroatoms contents. Therefore, this study brings enormous promise for low‐cost and scalable production of efficient electrodes for electrochemical energy storage.