Effect of conjugation level on the performance of porphyrin polymer based supercapacitors

Abstract In the field of electrochemical energy storage, porous organic polymers with ligand diversity have the advantage of structural and redox site adjustability. However, they suffer from low energy density and poor cycling stability. In the submitted paper, we described the conversion of a non-conjugated (regional conjugated) porphyrin polymer (denoted as NCPP) to the corresponding fully conjugated polymer (denoted as CPP), as well as the effect of conjugation degree on energy storage performance. The derived CPP has amorphous structure, rich porosity, nanosheet morphology and large surface area of 157 m2/g with pore volume of 0.39 cm3/g. As electrode for supercapacitor, the CPP displays superior supercapacitor performance including large capacity of 571 F/g at 1.0 A/g (maintaining 317 F/g at 20 A/g), high specific energy of 15.4 Wh/kg at specific power of 292 W/kg (much higher than that of NCPP which is 3.98 Wh/kg at 177 W/kg), and long cycling stability with 80% capacitance retention after 9000 continual charge/discharge cycles at a large current density of 6.0 A/g, showing great potential for energy storage application. The method is simple and versatile, thus providing an alternative approach for the design of new type of polymer based energy storage materials. Moreover, with rich electrochemically-active sites the derived CPP may find wide applications in fields such as sensors, electrocatalysis and so on.