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

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, use of CTFs as electrodes in supercapacitors is hampered by their low electrical conductivity and a strong stacking effect between adjacent CTF sheets. Herein, two series of hybrid carbon nano-onion-based CTFs are designed and successfully synthesized using an ionothermal process at 700 °C. The CTFs could undergo framework growth in two or four directions, which was related to a defined number of nitrile groups in the substrate. CTF counterparts without carbon nano-onions were also synthesized as reference materials. The carbon nanocomposites exhibited excellent specific capacitances, with the highest value exceeding 495 F g⁻¹. It should be emphasized that the specific capacitance value of hybrid materials was 1.5–2 times higher than that of the reference CTFs. This study examined the factors responsible for such a significant increase in electrochemical efficiency. This strategy has significantly expanded the scope and application of CTFs as electrode materials for electrochemical energy storage systems.