Nitrogen-Doped Porous Carbon with Staged Nanopore Formation for Capacitors

Abstract

The design of nanopore structures in porous carbon materials plays a crucial role in achieving high capacitance and rate performance in capacitors. This study introduced a method for the synthesis of high specific surface area nitrogen-doped porous carbon (HNPC) materials by staged nanopore formation. The method involved designing a composite reaction precursor using oxalic acid (H 2 C 2 O 4 ), p-phenylenediamine (PDA), and potassium hydroxide (KOH), as well as creating micropores during the pyrolysis process and constructing micropores and mesopores during potassium carbonate (K 2 CO 3 ) activation stage. HNPC materials synthesized in this study demonstrated a high specific capacitance and exceptional rate performance in aqueous electrolytes across a broad pH spectrum (acidic, neutral, and alkaline) as well as in organic electrolytes. Specific capacitances of 263.3 F g −1 , 366.1 F g −1 , and 304.4 F g −1 (at a scanning rate of 2 mV s −1 ) were attained in 1 M lithium sulfate (Li 2 SO 4 ), 6 M KOH, and 1 M sulfuric acid (H 2 SO 4 ) electrolytes, respectively, indicating high capacitance values. By configuring them as symmetric supercapacitors, they performed high energy densities of 8.2 Wh kg −1 and 22.9 Wh kg −1 in aqueous and organic electrolytes, respectively, while maintaining capacity retention rates of 81.2% and 83.9% after 10 000 and 5000 cycles.