Porphyrin‐Based Covalent Organic Polymer Wrapped MWCNT Electrodes under Moderate Salt Concentration for Super‐Stable Aqueous Sodium‐Ion Intercalated Sustainable Supercapacitor

Abstract

Abstract To rival commercial organic electrolytes, it is important to focus on safe, cheap aqueous electrolytes with lower salt concentration (≈5.0 m ) and a wider electrochemical stable potential window (ESPW). This study reports the facile synthesis of porphyrin‐based covalent organic polymers (PTZ‐COP, CBZ‐COP, and TPA‐COP) through a one‐pot aromatic electrophilic polycondensation reaction between pyrrole and monomeric aldehydes (PTZ‐CHO, CBZ‐CHO and TPA‐CHO). To enhance conductivity, these covalent organic polymers (COPs) were noncovalently wrapped on multiwall carbon nanotubes (MWCNTs), forming MWCNT@PTZ‐COP, MWCNT@CBZ‐COP and MWCNT@TPA‐COP. Among all, phenothiazine‐based COPs wrapped on MWCNT viz . MWCNT@PTZ‐COP stands out, exhibiting notable surface area and redox‐active moieties with high heteroatom (N, S) contents in the framework. These properties contribute to its superior performance in the form of an electrochemical double‐layer capacitor (EDLC) and pseudocapacitor. In the three‐electrode, the MWCNT@PTZ‐COP achieves a wider ESPW of 2.2 V, demonstrates a remarkable specific capacitance of 292.7 F g −1 along with an energy density 196.8 Wh kg −1 and power density of 752 W kg −1 , at a current density of 0.7 A g −1 in 5 m NaClO 4 . As‐designed symmetric supercapacitor cell of MWCNT@PTZ‐COP demonstrates an impressive specific capacitance of 55.5 F g −1 and energy density 37.3 Wh kg −1 , respectively. Additionally, it exhibits a high areal capacitance of 46.4 mF cm −2 in 5 m NaClO 4 . Moreover, it exhibits outstanding 100% capacitance retention after running 20 000 GCD cycles at 3.2 A g −1 . This system demonstrates the highest cell voltage for a porphyrin‐based COPs aqueous symmetric supercapacitor with a high energy density and stability.

Topics & Concepts