In situ growth of redox-active porous organic polymers on Ti3C2Tx MXene for high-performance pseudocapacitors†

Abstract

Redox-active porous organic polymers (POPs) are promising pseudocapacitive electrode materials for supercapacitors due to their tunable structures and ease of functionalization. However, their low intrinsic conductivity has hindered their performance as energy storage materials. To address this challenge, herein a POP with abundant redox-active moieties was in situ grown onto highly conductive Ti₃C₂T_x MXene to form a MXene/POP hybrid (denoted as MXene/HATN-DHAQ). The synergistic interaction between HATN-DHAQ and Ti₃C₂T_x MXene not only enhances the conductivity but also prevents the restacking and oxidation of Ti₃C₂T_x MXene nanosheets. As a result, MXene/HATN-DHAQ exhibits a high specific capacitance of 691.5 F g⁻¹ at 0.5 A g⁻¹, excellent rate performance (248.5 F g⁻¹ at 20 A g⁻¹), and remarkable long-term cycling stability with 87.7% capacity retention after 10 000 cycles at 20 A g⁻¹. Notably, the electrochemical performance of MXene/HATN-DHAQ significantly outperforms that of Ti₃C₂T_x MXene or HATN-DHAQ alone. Furthermore, an asymmetric supercapacitor device based on MXene/HATN-DHAQ achieves a high energy density of 20.5 W h kg⁻¹ at a power density of 338.3 W kg⁻¹, along with excellent cycling stability with 84.3% capacity retention after 10 000 cycles at 2 A g⁻¹. This work provides a valuable strategy to design and prepare MXene/POP hybrid materials for high-performance energy storage applications and devices.