Efficient faradaic supercapacitor energy storage using redox-active pyrene- and benzodithiophene-4,8-dione-tethered conjugated microporous polymers

Abstract

Conjugated microporous polymers (CMPs) are intriguing options for a wide range of applications; however, CMP-tethered energy storage devices such as supercapacitors have received relatively little investigation due to limitations in energy density, electronic conductivity, electrochemical/structural durability, and specific capacitance. We present here the synthesis of a unique sort of redox-active conjugated microporous polymers, Py-BDT and Py-Ph-BDT CMPs, based on pyrene (Py) and redox-active benzo[1,2-b:4,5-b′]dithiophene-4-dione (BDT) units as efficient and stable electrode components for supercapacitor energy storage devices. The CMPs exhibited outstanding thermal stabilities (T_d10: approximately 564 °C; char yield: approximately 70.5%) and surface areas (around 427 m² g⁻¹). Intriguingly, integrating the pyrene and redox-active BDT units into the CMP core leads to rapid charge transport, outstanding faradaic energy storage, and remarkable conductivity. As expected, the resulting CMPs show an excellent three-electrode capacitance of 712 F g⁻¹ at 0.5 A g⁻¹ current density, which is a better specific capacity than that of the previously reported conventional CMPs. A symmetric two-electrode supercapacitor constructed with the Py-Ph-BDT CMP displays an effective capacitance of 429 F g⁻¹ and an energy density of 38.21 W h kg⁻¹ at a potential of 0.8 V and maintains 80% of its beginning capacitance over 4000 cycles. Our research provides a simple route to combine various electroactive moieties with redox-active benzodithiophene-4,8-dione to develop outstanding supercapacitors.