Pore and Heteroatom Engineered Carbon Foams for Supercapacitors

Abstract

Carbonaceous materials are attractive supercapacitor electrode materials due to their high electronic conductivity, large specific surface area, and low cost. Here, a unique hierarchical porous N,O,S‐enriched carbon foam (KNOSC) with high level of structural complexity for supercapacitors is reported. It is fabricated via a combination of a soft‐template method, freeze‐drying, and chemical etching. The carbon foam is a macroporous structure containing a network of mesoporous channels filled with micropores. It has an extremely large specific surface area of 2685 m 2 g−1. The pore engineered carbon structure is also uniformly doped with N, O, and S. The KNOSC electrode achieves an outstanding capacitance of 402.5 F g−1 at 1 A g−1 and superior rate capability of 308.5 F g−1 at 100 A g−1. The KNOSC exhibits a Bode frequency at the phase angle of −45° of 18.5 Hz, which corresponds to a time constant of 0.054 s only. A symmetric supercapacitor device using KNOSC as electrodes can be charged/discharged within 1.52 s to deliver a specific energy density of 15.2 W h kg−1 at a power density of 36 kW kg−1. These results suggest that the pore and heteroatom engineered structures are promising electrode materials for ultrafast charging.