One-Step Site-Specific Activation Approach for Preparation of Hierarchical Porous Carbon Materials with High Electrochemical Performance

Abstract

Precise control of carbonization and activation for fabricating novel carbon materials and improving practical performance have continued to be a big challenge. Inspired by the aggregation of abundant inorganic elements on a special part in biomass for self-activation, we developed a novel site-specific activation strategy to prepare porous carbon materials with controllable morphology and microstructure based upon regulating the activator molecule distribution for aggregation of activators on specific sites in a carbonaceous precursor. The fabrication of porous carbons was carried out not only in one step of direct calcination but with much reduced use of activators, demonstrating comparative or even preferable structure and performance characteristics of porous carbon compared with that of the conventional activated method. Porous carbons featured with a 3D flake interconnection network were obtained by site-specific activation with hierarchical porosity and unique micropore size distribution. The obtained porous carbon materials displayed excellent electrochemical performance with high specific capacitance (375 F g–1 at 0.1 A g–1) and excellent capacitance retention (276 F g–1 at 20 A g–1) used as electrode materials. Meanwhile, the symmetric supercapacitors assembled by the porous carbon could yield specific energy density up to 7.81 Wh kg–1 with excellent power density (9600 W kg–1) and outstanding cycling stability (99.8% capacitance retention after 10 000 charge/discharge cycles at 2 A g–1) in 1 M H2SO4 electrolytes.