Incorporating Conducting Polypyrrole into a Polyimide COF for Carbon-Free Ultra-High Energy Supercapacitor

摘要

Redox-active covalent organic frameworks (COFs) store charges but possessinadequate electronic conductivity. Their capacitive action works bystoring H+ ions in an acidic electrolyte and is typically confined to a smallvoltage window (0–1 V). Increasing this window means higher energy andpower density, but this risks COF stability. Advantageously, COF’s largepores allow the storage of polarizable bulky ions under a wider voltage thusreaching higher energy density. Here, a COF–electrode–electrolyte systemoperating at a high voltage regime without any conducting carbon or redoxactive oxides is presented. Conducting polypyrrole (Ppy) chains are synthesizedwithin a polyimide COF to gain electronic conductivity (≈10 000-fold).A carbon-free quasi-solid-state capacitor assembled using this compositeshowcases high pseudo-capacitance (358 mF cm~(?2)@1 mA cm~(?2)) in anaqueous gel electrolyte. The synergy among the redox-active polyimideCOF, polypyrrole and organic electrolytes allows a wide-voltage window(0–2.5 V) leading to high energy (145 μWh cm?2) and power densities(4509 μW cm~(?2)). Amalgamating the polyimide-COF and the polypyrroleas one material minimizes the charge and mass transport resistances.Computation and experiments reveal that even a partial translation of themodules/monomers intrinsic electronics to the COF imparts excellent electrochemicalactivity. The findings unveil COF-confined polymers as carbonfreeenergy storage materials.