Binder-free metal–organic framework-based core–shell arrays for supercapacitors

Abstract

Supercapacitors (SCs) are regarded as promising electrochemical energy storage devices, where the electrodes are vital in determining the performance of the devices. Metal–organic frameworks (MOFs) have recently emerged as suitable electrode materials or templates/precursors of electrode materials for SCs. The key to utilizing MOF-based electrode materials is to address their low electronic conductivity and poor stability issues. Therefore, rational design and fabrication of binder-free MOF/MOF derivative arrays is considered the most promising strategy to address these challenges. Another way to overcome the above limitations is to combine MOF-based materials with secondary electrochemically active materials to form composites with delicate architectures, such as core–shell structures, where the complementary and synergetic effects of different components give rise to enhanced energy storage capability. There are growing numbers of studies on MOF-based core–shell hybrid arrays directly constructed on current collectors. In this frontier review, we first introduce two synthesis strategies of constructing MOF-based core–shell arrays: growing MOFs on transition metal oxide (TMO) arrays and on a reactive hard template. Subsequently, core–shell arrays using MOF derivatives as core or shell materials are summarized. Finally, the potential challenges in binder-free core–shell array electrodes and possible solutions to these challenges are also discussed.