One-tube self-activation of hydrogel for the preparation of hydrophilic N, S co-doped hierarchical porous carbon: Formation mechanism and supercapacitor performance

Abstract

The porous carbon of supercapacitors usually is synthesized via an activation procedure based on traditional activators, such as KOH, H₂O, and CO₂. Herein, a self-activation strategy is proposed to prepare N/S co-doped hierarchical porous carbons (NSHPC). Poly(2-acrylamide-2-methylpropane sulfonic acid potassium) (PAMPSK) hydrogels as precursors are obtained via a self-polymerized reaction, and they are annealed at 800 °C to result in NSHPC-800 with the best properties. NSHPC-800, used as electrode materials for supercapacitors, exhibits a prominent rate capability of 256.2 F g⁻¹ at 50 A g⁻¹. Moreover, the symmetric supercapacitor exhibits a high energy density of 7.08 Wh kg⁻¹ at ultrahigh power density of 25,000 W kg⁻¹. Two capacitors are connected in series to light up a red light emitting diode for 60 s. This work may provide a new strategy for the synthesis of hydrophilic porous carbons, as well as a systematic investigation of the self-activation process and mechanism.