Metal-organic frameworks: A comprehensive review on common approaches to enhance the energy storage capacity in supercapacitor

Metal-organic frameworks (MOFs) are a class of crystalline materials formed by the assemblage of inorganic metal ions and organic ligands and are known for their porous nature, high surface areas, and tuneable pore sizes. Unfortunately, they are also known for having low conductivity and poor stability making them undesirable for energy storage applications, especially in batteries and supercapacitors. To combat this issue, several strategies are being followed by researchers in the view of improving its conductivity as well as energy storage properties with a focus on specific capacitance and energy density. In this review, we specifically focussed on commonly employed approaches which involve integrating MOFs with redox-based metal/linkers and the combination of MOFs with diverse functional or conductive materials to synthesize composites and utilizing MOF as templates to generate stable derivatives. Moreover, the focus on the morphology of MOF-based materials and the factors affecting it are also emphasized. Further, a summary of the challenges and insights associated with each of these approaches is provided.