Flexible Redox Active Porous Organic Polymer Gels via Noncovalent Assembly for High Energy Supercapacitors

Abstract

Porous organic polymers (POPs) have emerged as promising materials for energy storage due to their structural tunability and intrinsic functionality. However, their practical implementation in flexible electrochemical devices remains hindered by poor processability, limited capacitance, and inadequate electrochemical stability stemming from their insoluble powdered form. Herein, we report a flexible POP hydrogel engineered via the Buchwald–Hartwig coupling of guanidine moieties, followed by a freeze–thaw process that drives gelation through extensive noncovalent interactions with phytic acid. This strategy transforms the rigid POP into a mechanically robust, processable gel with enhanced flexibility and electroactivity. When employed as an organic electrode for supercapacitors in 3 M H2SO4, the PA-POP hydrogel delivers a high specific capacitance of 205.43 F g–¹ at 5 mV s–¹ and retains 95% of its capacity after 10,000 cycles at 1 A g⁻¹. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses reveal that the guanidine and phosphate functionalities actively participate in redox processes via a proton-coupled electron transfer (PCET) mechanism. As a proof of concept, a flexible symmetric device constructed using PA-POP electrodes exhibits a specific capacitance of 85 F g–1 at 1 A g–1, with an energy density of 3.8 Wh L–1 and a power density of 80 W L–1, maintaining 82% of its capacitance over 10,000 cycles. This work presents a new paradigm for engineering processable and flexible organic electrode materials for high-performance supercapacitors.