Template-Free Synthesis of Honeycomblike Porous Carbon Rich in Specific 2–5 nm Mesopores from a Pitch-Based Polymer for a High-Performance Supercapacitor

A template-free strategy has always been attractive to design and fabricate advanced carbon materials with tunable nanostructures from cheap precursors. Herein, honeycomblike mesoporous carbons (HPCs) are prepared from pitch-based polymers through a self-assembly foaming strategy without using any templates. Rich mesopores specific in sizes of 2–5 nm and abundant open-ended honeycomblike holes endow a hierarchical pore-in-pore feature of HPCs and an ultrahigh specific surface area (3473 m2 g–1). With their superior structure, HPCs can deliver a high supercapacity of 339 F g–1 at a current density of 1 A g–1 in 6 M KOH aqueous electrolyte and retain 85.6% of the capacity even at a current density of 50 A g–1. Meanwhile, a supercapacitive cell assembled by two HPC electrodes yields a conspicuously ultrahigh energy density of 34.5 Wh kg–1 (12.8 Wh L–1) at a high power density of 679.4 W kg–1 (251.4 W L–1). This work provides a new method for the controllable synthesis of advanced carbon materials from pitch and presents further applications in flexible electrochemical supercapacitors.