Morphology-Dependent Covalent Organic Polymers Exhibit Tunable Charge Storage Performance in Supercapacitor Application

Covalent organic polymers (COPs) emerged as a potential porous carbon material for diverse applications in various fields such as catalysis, gas storage and separation, sensing, energy production, and storage application because of their extended pi-conjugation, porosity, chemically stability, and robust structure. Electrochemical energy storage systems such as supercapacitors can store energy with great power density, as well as high specific capacitance. Moreover, these systems efficiently release energy with a high-power density over a short period of time. In these circumstances, modulating the internal porosity by tailoring the functionality in the COP material for specific energy storage remains a challenge. Herein, we have developed four different alkyl chain-modified truxene-DAB COPs (Me-TRUX-DAB, Et-TRUX-DAB, But-TRUX-DAB, and Pent-TRUX-DAB)-based supercapacitors. The COPs were prepared via solvothermal Schiff base reaction between alkyl (methyl to n-pentyl)-Truxene-tricarbaldehyde (R-TRUX) with 3,3 '-diaminobanzidine (DAB). Tailoring the alkyl chain in R-TRUX-DAB COPs materials creates tunable porosity; therefore, a wide range of surface area was observed, which also correlates with unique morphology (hollow spherical to sheet-like structure). Surface area gradually decreases from the methyl to butyl-TRUX-DAB system, but surprisingly Pent-TRUX-DAB COP shows the maximum surface area. Consequently, specific capacitance decreases from methyl to butyl-TRUX-DAB COPs and the Pent-TRUX-DAB system shows the maximum specific capacitance of 634 F g(-1) at 1 A g(-1) with 92% retention of capacitance after 3000 charge-discharge cycles. The Pent-TRUX-DAB COP shows high specific capacitance due to the delocalization of electrolyte ions throughout the highly accessible surface area. These results agreed with the observed surface areas of the COP materials.