Flexible Solid-State Supercapacitor Based on a Metal–Organic Framework Interwoven by Electrochemically-Deposited PANI

TLDR

Metal‑organic frameworks are promising supercapacitor electrodes, but their poor conductivity limits capacitance and rate performance. The study develops a strategy to reduce MOF bulk resistance by interweaving MOF crystals with electrochemically deposited polyaniline chains. Cobalt‑based ZIF‑67 crystals were grown on carbon cloth and coated with polyaniline to form a flexible conductive porous electrode (PANI‑ZIF‑67‑CC) that preserves the MOF structure, and a symmetric flexible solid‑state supercapacitor was assembled. The PANI‑ZIF‑67‑CC electrode achieved an extraordinary areal capacitance of 2146 mF cm⁻² at 10 mV s⁻¹, demonstrating the strategy’s potential for designing high‑performance MOF‑based supercapacitors and other electrochemical devices.

Abstract

Metal-organic frameworks (MOFs) have received increasing attention as promising electrode materials in supercapacitors (SCs). Yet poor conductivity in most MOFs largely thwarts their capacitance and/or rate performance. In this work, an effective strategy was developed to reduce the bulk electric resistance of MOFs by interweaving MOF crystals with polyaniline (PANI) chains that are electrochemically deposited on MOFs. Specifically we synthesized cobalt-based MOF crystals (ZIF-67) onto carbon cloth (CC) and further electrically deposited PANI to give a flexible conductive porous electrode (noted as PANI-ZIF-67-CC) without altering the underlying structure of the MOF. Electrochemical studies showed that the PANI-ZIF-67-CC exhibits an extraordinary areal capacitance of 2146 mF cm(-2) at 10 mV s(-1). A symmetric flexible solid-state supercapacitor was also assembled and tested. This strategy may shed light on designing new MOF-based supercapacitors and other electrochemical devices.