Understanding the Influence of Particle Morphology on the Capacitive Performance of Conductive Layered Metal-Organic Frameworks

Abstract

Two-dimensional layered metal-organic frameworks (MOFs), characterised by their combined high intrinsic porosities and electrical conductivities, have emerged as one of the most promising electrode materials for next-generation energy storage devices, particularly supercapacitors. Several such MOFs have displayed encouraging performances in supercapacitors with a wide range of electrolytes, and have exhibited specific and areal capacitances on par with or exceeding state-of-the-art carbon materials.^1-3 This has raised the prospect of using these materials in commercial devices, and their well-defined structures make them promising model electrode materials for supercapacitor structure-property investigations. However, layered MOFs can be synthesised with a range of particle morphologies, and hence 3D pore structures, as well as different degrees of particle agglomeration. Minimal work has been performed to understand how these factors impact the capacitive performances of these frameworks, and existing literature has struggled with small differences in observed morphology and low control over the samples.⁴ This has cast doubts over reported results, and has hindered both the development of MOF-based supercapacitors and their implementation as model electrodes.