Progress in metal-organic frameworks and their carbon-based composites for supercapacitor

Supercapacitors (SCs) have received a lot of attention because of their ability to deliver more power than secondary batteries and higher energy than traditional capacitors. They can be used as independent power sources for appliances that need short-term power. The major limitation of SCs is low energy density and many attempts were made to mitigate this drawback. Metal-organic frameworks (MOFs) are crystalline porous materials consisting of central metal ions coordinated with organic ligands to form tunable frameworks. Due to the high crystallinity, and tailored porosity and chemical compositions, MOFs were utilized as electrode materials for SCs. Nevertheless, the low stability and rapid structural collapse, which results in poor cycling stability are some of the limitations of pristine MOFs when employed in the field of SCs. Given these, recent efforts have demonstrated that the combination of MOFs with functional materials particularly carbon-based material to form MOF/C nanocomposites provides a facile avenue to overcome the above-mentioned limitations. This review discusses the synthesis of various nanocomposites of MOFs and their SC performance systematically. Also, the current challenges and future direction of MOFs and its carbon-based composite are summarized.