A Highly Robust and Conducting Ultramicroporous 3D Fe(II)‐Based Metal–Organic Framework for Efficient Energy Storage

Abstract Exploitation of metal–organic framework (MOF) materials as active electrodes for energy storage or conversion is reasonably challenging owing to their poor robustness against various acidic/basic conditions and conventionally low electric conductivity. Keeping this in perspective, herein, a 3D ultramicroporous triazolate Fe‐MOF (abbreviated as Fe‐MET) is judiciously employed using cheap and commercially available starting materials. Fe‐MET possesses ultra‐stability against various chemical environments (pH‐1 to pH‐14 with varied organic solvents) and is highly electrically conductive (σ = 0.19 S m −1 ) in one fell swoop. By taking advantage of the properties mentioned above, Fe‐MET electrodes give prominence to electrochemical capacitor (EC) performance by delivering an astounding gravimetric (304 F g −1 ) and areal (181 mF cm −2 ) capacitance at 0.5 A g −1 current density with exceptionally high cycling stability. Implementation of Fe‐MET as an exclusive (by not using any conductive additives) EC electrode in solid‐state energy storage devices outperforms most of the reported MOF‐based EC materials and even surpasses certain porous carbon and graphene materials, showcasing superior capabilities and great promise compared to various other alternatives as energy storage materials.