Robust cobalt phthalocyanine-based covalent organic framework/chitosan aerogel for high-performance supercapacitor

Abstract

Covalent organic frameworks (COFs) usually exist in the form of powder, which is not conducive to electrical conductivity and difficult to be molded, especially into aerogel, tremendously limiting its application in supercapacitors. In this work, the robust cobalt phthalocyanine-based COF/chitosan (CoPc-COF/CS) aerogels were successfully prepared by freeze drying the water solution of CoPc-COF and 2,4,6-triformylphloroglucinol (Tp, crosslinker) in chitosan (CS). The CoPc-COF/CS aerogels not only have good mechanical strength and compressibility but also maintain the COF original crystallinity and functionalities. Notably, the porous network structure of CoPc-COF/CS aerogels provides rich active surfaces and short ion diffusion paths. Meanwhile, the rich nitrogen groups on the surface of aerogel and CoN₄ centers improve their specific capacitance in the three-electrode system. The obtained CoPc-COF/CS aerogel exhibits excellent capacitive performance (556 F g⁻¹ at 1 A g⁻¹) in the three-electrode system. Furthermore, the asymmetric supercapacitor (CoPc-COF/CS aerogel//AC ASC) assembled using CoPc-COF/CS aerogel and activated carbon (AC) electrodes exhibited a high energy density of 31.9 Wh kg⁻¹ at 750 W kg⁻¹ and good cycle stability (87.5 % after 5000 cycles). The capacitive performances of CoPc-COF/CS aerogel promising for practical applications in supercapacitors.