Development of heteroatom-rich fluorene-based benzoxazine-linked porous organic polymers as potential candidates for energy storage

Background: Engineering of porous organic polymers (POPs) with redox activity, considerable porosity, and high conductivity is more crucial for their practical applications in energy storage systems. Methods: In this context, we describe the synthesis and comprehensive characterization of two novel fluorene-based benzoxazine-linked POPs as efficient electrode materials for supercapacitors. The polymers have been obtained in high yields by direct polymerization of different triamine derivatives, diphenol and p-formaldehyde. The structural integrity of the benzoxazine-based polymer linkage and porosity parameters have been readily investigated through FTIR, solid-state ¹³C NMR spectra and N₂ sorption analysis. The benzoxazine backbone endows the POPs with abundant N and O heteroatoms, making them efficient candidates for storing energy. Significant Findings: We have found that the benzoxazine-linked polymers exhibit outstanding electrochemical specific capacitances. Of the two polymers synthesized investigated, Fl-TPA POP displayed higher electrochemical specific capacitance of up to 276 F g^‒1 at 0.5 A g^‒1 than Fl-Cz POP, which is attributed to the higher microporosity and the larger specific surface area. Furthermore, Fl-TPA POP exhibited the maximum energy density of 38.33 Wh kg⁻¹ at a power density of 250 W kg⁻¹, top cyclic stability after 5000 charge-discharge cycles (95.23 %) and the lowest ohmic internal resistance (21.83 Ω).