Microporous Organic Polymer‐Derived Nitrogen‐Doped Porous Carbon Spheres for Efficient Capacitive Energy Storage

Abstract

A facile and template‐free synthetic approach was utilized to obtain a series of nitrogen and oxygen‐doped microporous carbon spheres (CTS‐X‐700) from carbazole‐terephthalaldehyde based co‐polymer spheres (CTS). The inherent spherical morphology of the co‐polymer remained intact even after activation at high temperature (700 °C). The synthesized materials exhibit BET surface area of up to 1340 m2 g−1 with an interconnected porous network consisting of ultramicropores and supermicropores along with a small amount of mesopores. Moreover, a good balance of heteroatom surface functionalities (N content up to 3.2 % and O content up to 12 %) was maintained without compromising the porosity by systematically varying the activation conditions. These features result in a high specific capacitance value of 407 F g−1 at 1.0 A g−1 in aqueous acid electrolyte with a three‐electrode system and superior cycle stability of 100 % capacitance retention even after 10000 cycles. Furthermore, the high energy density (10.6 W h kg−1 at a current density of 0.5 A g−1) in an aqueous electrolyte of the assembled supercapacitor device further demonstrates the possible applications of the synthesized materials as high‐performance energy storage devices.

Bottom‐Up Construction of Conjugated Microporous Polyporphyrin‐Coated Graphene Hydrogel Composites with Hierarchical Pores for High‐Performance Capacitors

“…Furthermore, it also matches or excels other similar electrodes reported previously listed in Tab S2, suggesting the importance of simultaneously integrating micropores and mesopores into the macroporous GH frameworks. And it validated that the synergistic effect of micro‐, meso‐ and macropores could enhance the electrochemical performance greatly . For the real application of capacitors, an excellent cycling capability is prerequisite.…”

“…[19] And rapid growth could be detected with the increasing of the pressure (0.9 to1.0), indicative the existence of macropore. [20] But different with the isotherm of GH, the GH-CMP composites also exhibits a vertical growth in the low pressure range (P/P 0 < 0.01), implying the successfully introduction of micropore into the composites. [21] According to the nitrogen adsorption-desorption analysis, GH-CMP possesses a specific surface area of 219.2 m 2 g À 1 much higher than that of the GH precursor (99.7 m 2 g À 1 ).…”

“…As shown in Figure a and 5b, typical isotherm with obvious hysteresis loop at the relative pressure (P/P 0 ) from 0.5 to 1.0 could be observed for both the GH and GH‐CMP, suggesting the existence of mesopore . And rapid growth could be detected with the increasing of the pressure (0.9 to1.0), indicative the existence of macropore . But different with the isotherm of GH, the GH‐CMP composites also exhibits a vertical growth in the low pressure range (P/P 0 <0.01), implying the successfully introduction of micropore into the composites .…”

“…And it validated that the synergistic effect of micro-, meso-and macropores could enhance the electrochemical performance greatly. [20] For the real application of capacitors, an excellent cycling capability is prerequisite. Hence, the cycling stability of GH-CMP was initially evaluated at 2 A g À 1 via continuous charge/discharge technology.…”

Tuning Nitrogen Species in Two‐Dimensional Carbon through Pore Structure Change for High Supercapacitor Performance

“…Continuous efforts to increase energy density without sacrificing power density and cycle life are still hot topics. [4] However, pore engineering is an effective way that cannot be ignored in improving the electrochemical performance of carbon materials. The abundant pore structure can provide high surface area and electrolyte storage area, which can promote the rapid transfer of electrolyte ions, enrich the buffer channel of ions, and improve the capacity of capacitance and rate.…”