Metal-Organic Frameworks (MOFs) composited with nanomaterials for next-generation supercapacitive energy storage devices

Abstract

Nanostructured materials (e.g., metal oxides, polymers, carbon materials) have been extensively investigated for the advancement of energy storage technologies. They offer novel physicochemical properties and uncover new prospects for various modern applications. Their distinguished features such as higher surface energy as well as activity than bulk materials provide more electroactive sites leading to high capacity utilization of the electrode materials suitable for energy storage systems. However, these nanomaterials often have several shortcomings such as insufficient pore channels, which limit their applications for practical purpose. On the other hand, metal-organic frameworks (MOFs) have emerged as interesting candidates owing to their extremely high surface area and higher porosity which make them suitable candidate for various applications. In addition, their porous structures permit efficient electrolyte infiltration, which can shorten the diffusion and transport pathways for electrolyte ions, accelerating kinetics, and deliver rapid charge-discharge rate. However, the low conductivity of MOFs has been a persistent issue due to which their applications in energy storage devices are not widely explored. Recent research has been focused on the development of such materials or combination of materials, which can resolve both the issues. In this regard, some efforts have been made to synergistically improve the efficiency of energy storage devices in particular of supercapacitors by combining highly porous MOFs with conducting nanomaterials (CNMs) such as graphene, CNTs, carbon black, and nanoporous carbon. Recent reports reveal that synergistic effects of MOFs with CNMs result in drastic enhancement of the supercapacitor performance. The MOF-CNM combination not only facilitates the effective utilization of the other active materials but also enhances the mechanical strength and conductivity of the composite synergistically. In this chapter, the synthesis, characterization, and the supercapacitor performance based on existing MOFs and their composite with different nanomaterials will be discussed. Moreover, future prospects and necessary advancement required in the energy storage field will be summarized. © Springer Nature Switzerland AG 2019. All Rights Reserved.