A robust and conductive 3D Fe(ii) MOF as a durable cathode for aqueous zinc-ion batteries

Abstract

A highly robust 3D ultramicroporous Fe-MOF (abbreviated as Fe-MET), constructed from very inexpensive, abundant, and commercially available materials, exhibits high conductivity (σ = 0.19 S m⁻¹) and can sustain under various conditions exhibiting exceptional stability (pH 1–14, numerous organic solvents, over 1 year in air, and in 1 M Zn(CF₃SO₃)₂ solution), as confirmed by PXRD, FESEM, FTIR, etc. The high conductivity coupled with a high BET surface area of 413 m² g⁻¹ and ultramicroporous homogeneous pore size of 4.6 Å made Fe-MET a promising material for the faradaic process during the electrochemical process. The solid-state AZIB coin cell fabricated using Fe-MET as the cathode delivers a maxmimum specific capacity of 34 mA h g⁻¹ at 20 mA g⁻¹ as a standalone electrode, decent energy, and a power density of 54.4 W h kg⁻¹ and 5.64 W kg⁻¹, exhibiting over 60% capacitance retention after 2100 cycles with no significant loss in coulombic efficiency. With these advances, Fe-MET has been recognised as a promising, pyrolysis-free standalone electrode material for efficient energy storage applications.