Spirobifluorene-Based Conjugated Microporous Polymer-Grafted Carbon Nanotubes for Efficient Supercapacitive Energy Storage

Conjugated microporous polymers (CMPs) are promising electrode materials for electrochemical energy storage, but their poor redox activity and electric conductivity limit their practical applications. Herein, CMPs obtained from the Buchwald–Hartwig coupling reaction using a spirobifluorene bromide core and p-phenylenediamine linker (SACMPs) are grafted onto the multiwalled carbon nanotube (MWCNT) via one-step in situ polymerization. The as-prepared composite (MWCNT@SACMP) exhibits a high surface area of 514 m2 g–1, excellent redox activity, and reasonable conductivity. As expected, MWCNT@SACMP presents a high specific capacitance of 594 F g–1 at a current density of 1.0 A g–1 when the content of MWCNTs is around 10 wt %, which is improved by 252% from the 236 F g–1 of SACMP. A symmetric two-electrode supercapacitor assembled with MWCNT@SACMP shows an efficient specific capacitance of 254 F g–1 and an energy density of 28.53 W h kg–1 at a power density of 900 W kg–1 and can retain 84.38% of its initial capacitance after 6000 cycles. This work thus presents a promising CMP/MWCNT composite material for supercapacitor energy storage.