Nitrogen- and oxygen-containing micro–mesoporous carbon microspheres derived from m-aminophenol formaldehyde resin for supercapacitors with high rate performance

Abstract

Nitrogen- and oxygen-containing micro-mesoporous carbon microspheres (NO-MMCMs) were prepared by a self-assembly hydrothermal synthesis in the presence of m-aminophenol as a carbon and nitrogen co-precursor and block copolymer F127 as a soft template, followed by carbonization and activation with KOH. The NO-MMCMs possess a high specific surface area (up to 3203 m² g⁻¹), large pore volume with a well-balanced micro- and mesoporosity (up to 1.93 cm³ g⁻¹), moderate heteroatom content (6.64 at%) and micrometer-sized sphere-like morphology. Moreover, the heteroatom contents and porosity parameters (e.g. surface area and pore volume) can be easily controlled by the carbonization temperature in the range of 600–850 °C. When tested as a supercapacitor electrode in a three-electrode system using 6 M KOH solution as the electrolyte, the typical NO-MMCMs (NO-MMCMs-600) displays a high specific capacitance (309 F g⁻¹ at 0.1 A g⁻¹), excellent rate capability (229 F g⁻¹ at 20 A g⁻¹ with capacitance retention of 74%) and outstanding cycling stability (95% capacity retention after 10 000 charge/discharge cycles at 10 A g⁻¹). Furthermore, high performance of reversible specific capacitance of 200 F g⁻¹ at 20 A g⁻¹ with high rate capability of 77% can be achieved in a two-electrode cell. The superior capacitive performances may be mainly because of both the spherical morphology and the high-surface-area hierarchical microporous/mesoporous structure, which allow the rapid transport of electrolyte ions through the carbon matrix, as well as the excellent synergistic effect of co-doping of N and O. These encouraging results demonstrate that the NO-MMCMs electrode materials with high current charge and discharge capability hold great potential for supercapacitor applications, where a fast charge/discharge is required.