Electrochemical Properties of Nitrogen-Enriched Templated Microporous Carbons in Different Aqueous Electrolytes

Abstract

Ordered microporous carbon materials with controlled chemical and physical properties were synthesized by one-step nanocasting process using different carbon precursors. Large amount of heteroatoms, particularly oxygen and nitrogen species were presented in the carbon matrix. The interactions between the electrolyte ions and the surface functionalities were investigated in detail under various electrolyte environments. The electrochemical studies have revealed that different pseudo-processes occurred in proton-rich and proton-free electrolyte solutions. In proton-rich electrolyte environment, the faradaic processes are mainly due to the proton exchange between the nitrogen and oxygen species on the carbon electrode with the electrolyte. On the other hand, in proton-free electrolytes, nitrogen species was shown to play very important role in terms of the adsorption/desorption of K+ ions when negatively polarized in K+ containing electrolytes. The faradaic interaction between K+ ions and the nitrogen functionalities are stronger at the more negative potential. Very high gravimetric capacitance of 452 F/g and large capacitance retention of 97% at high discharge rate was achieved by the nitrogen-enriched carbon with moderately developed surface area. The superior capacitive performances of the templated carbons are closely linked to the ordered hierarchical porous structure, the adequate microporosity as well as the presence of suitable surface functionalities.