Ionic Liquid Derived Heteroatom-Adaptive Porous Carbon Electrode Harness High-Performance Supercapacitors: Momentous Roles of Microstructure and Self-Doped Bridge Active Sites

Abstract

Optimized carbon-based materials with defined morphology and porous structure are the impetus for enhancing the energy density of supercapacitor. However, the poor electrode charge and ion kinetics performance limits their widespread commercial application. Herein, the ionic liquid-derived various heteroatoms and bridge active sites have been successfully incorporated in porous carbon materials as the favorable electrodes for supercapacitors via a simply one-step pyrolysis tactics. The effects of ionic liquids with different anion compositions and carbonization temperature on the specific surface area, microstructure and capacitive performance of porous carbon have been systematically explored. As a result, the derived N, S doped and self-adaptive carbon sample (SPC-900) possess the appropriate heteroatom content (8.4 at.% N and 0.99 at.% S) and large specific surface area (995.5 m2 g-1) with ample porosity (0.4 cm3 g-1), which is beneficial to exhibit a favorable supercapacitor performance with specific capacitance of 234.8 F g-1 at 1 A g-1 and a remarkable capacitance retention rate of 84.15% after 8,000 cycles at 5 A g-1. The fabricated supercapacitor of SPC-900||SPC-900 affords a remarkable energy density of 11.9 Wh kg-1 at a power density of 489.2 W kg-1, while maintaining a capacitance retention of 82.1% over 10,000 cycles. Density functional theory research reveals that the synergistic effect between heteroatoms doping and C-S-C bridge active site can effectively lower the adsorption energy of electrolyte ion and thus strengthen the energy storage performance. This study can offer valuable insights into the ionic liquid-derived heteroatom self-adaptive porous carbon in supercapacitors.

Keywords: Porous carbon material, ionic liquid, Heteroatom self-adaptive, Bridge active site, Supercapacitor