Hierarchical porosity of hybrid carbon nanomaterials based on a covalent triazine framework for high-performance capacitive energy storage

Abstract

Covalent triazine frameworks (CTFs) constitute an emerging class of high-performance materials due to their porosity and the possibility of structural control at the molecular or atomic level. However, the use of CTFs as electrodes in supercapacitors is hampered by their low electrical conductivity and a strong stacking effect between adjacent CTFs. Herein, two series of hybrid carbon nano-onion-based CTFs were designed and successfully synthesized using an ionothermal process at 700 °C. The CTF could undergo framework growth in two or four directions, which was related to the presence of a defined number of nitrile groups in the substrate. CTF counterparts without carbon nano-onions were also synthesized as reference materials. The hybrid materials exhibited excellent specific capacitances, with the highest value exceeding 495 F g-1. It should be emphasized that the specific capacitance value for hybrids was 1.5-2 times higher than that for the reference CTFs. In this study, we examined the factors responsible for such a large increase in electrochemical efficiency. This strategy has significantly expanded the scope and application of CTFs as high-performance electrode materials for electrochemical energy storage systems.

Rational design of carbon nanocomposites with hierarchical porosity: a strategy to improve capacitive energy storage performance

“…One of them, i.e., tetraarylpyrrole[3,2-b]pyrrole, was applied for the first time by our group as a core in a CTF structure. 6 It is well known that a small amount of the CNO is enough to markedly increase the surface area of the hybrid material and improve its electrochemical properties. 34…”

“…In connection with the above guidelines, we proposed a combination of carbon nanostructures and spherical multilayer fullerenes (called carbon nano-onions, CNOs) with covalent triazine frameworks (CTFs) to create nanocomposites for SCs. 5,6 The combination of materials with differential chemical characters increases the capacity and porosity of electrodes, reaching better electrochemical performances. 7 Moreover, combining faradaic and non-faradaic processes in SCs can achieve higher energy and power density while maintaining long-term electrochemical stability.…”

“…1,14,[17][18][19][20][21] We used nitrogen-rich triazine units that form CTFs to modify the CNO surface. 5,6 CTFs are stable and can withstand harsh acidic or alkaline conditions that are destructive to other porous organic polymers. CTFs possess highly conjugated structures and exhibit semiconductive properties, making it possible to use them in SCs.…”