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Metal-organic frameworks (MOFs) belong to a novel class of materials with several advantages (e.g., ultrahigh porosity, tunable pore size distribution, convenience of synthesis, and structural tailor-ability). However, the insulating nature of MOFs is often recognized as a limiting factor in the extension of their applications, especially in electronic fields. In light of such limitations, various functional or conductive materials have been mixed/intercalated with MOFs to improve their potential for such applications (e.g., rechargeable batteries, optoelectronics, and supercapacitors). Lately, many of these composite materials have been recognized as next-generation electrodes for the development of efficient supercapacitors. In this review article, we have critically reviewed the recent advancements in supercapacitor applications of MOFs and their derived composite structures. Further, we have also discussed the application of various categories of electrolytes (e.g., aqueous, organic, ionic liquids, solid-state, and redox electrolytes) and their impacts on the development of MOF-based supercapacitors. [ABSTRACT FROM AUTHOR]

The application of porous and conductive composite materials in energy storage devices has received great attention in the recent years. Porous materials, such as metal-organic frameworks (MOFs), possess features like large specific surface area, mesoporous structures, and multiple reaction sites that make them attractive for energy storage devices. Further, the integration of MOFs with suitable conducting agents is a promising strategy to introduce additional conductive pathways in them, which facilitates fast charge transfer. In the present work, we report synthesis and supercapacitor application of a ZIF-67/PEDOT heterostructure composite. The prepared ZIF-67/PEDOT composite, when analyzed for electrochemical performance in three-electrode systems, has delivered a specific capacitance of 106.8 F/g at a current density of 1 A/g. This value is significantly better than that attaintable with only pristine ZIF-67 electrode (34.75 F/g at 1 A/g). Extending the study, two ZIF-67/PEDOT electrodes have been used to assemble an all-solid-state symmetrical supercapacitor, which delivers excellent values of energy density (∼11 Wh/kg) and power density (200 W/kg). Hence, this work paves the way for the potential application of ZIF-67/PEDOT composite in the development of next-generation supercapacitors. Image 1 • Incorporation of PEDOT in ZIF-67 benefits high conductivity and large specific surface area. • ZIF-67/PEDOT has been explored as a supercapacitor electrode material. • The assembled 1.6 V device delivered high energy (11 Wh/kg) and power (200 W/kg) densities. • Supercapacitor device has a long cycle life (93% capacity retention even after 4000 charge-discharge cycles). [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) are gaining interest in the energy sector due to its 2D chemistry and heterogeneous characteristics however its stability for the long run and poor electrical conductivity are pushing the researchers to make their hybrid. Herein we synthesized the hybrid WS 2 nanorods and Co 3 S 4 microspheres composite material which attained a high energy density of 47.3 Wh/kg along at a high-power density of 512 W/kg. The hollow Co 3 S 4 microspheres were synthesized using highly porous ZIF-67 as a precursor. Furthermore, these hollow Co 3 S 4 microspheres are in-situ modified by combining with WS 2 nanostructures to enhance its energy density. The electrodes with the synthesized hybrid material deliver the specific capacitance of 412.7 F/g at the current density of 1 A/g, Additionally, two equal weighted Co 3 S 4 /WS 2 composite electrodes are used to fabricate an all-solid-state symmetrical supercapacitor device with PVA-1M H 2 SO 4 polymer gel electrolyte, exhibiting a wide potential window of 2 V with 92% cyclic stability (2000 charge-discharge cycles) demonstrates its potential applicability for the supercapacitor application. The excellent electrochemical performance and splendid cyclic stability are attributed to the synergy of high surface area ZIF-67 derived Co 3 S 4 microsphere for fast charge transfer with 2D networked WS 2 material responsible to provide high energy density. Image 1 • A hybrid Co 3 S 4 /WS 2 composite was prepared using a one-step solvothermal method. • The hybrid composites deliver the highest specific capacitance of 412.7 F/g at the current density of 1 A/g. • A solid-state symmetrical supercapacitor was assembled with PVA-1M H 2 SO 4 gel electrolyte as a separator. • With wide potential window of 2 V, the fabricated device attained a high energy density of 47.3 Wh/kg along at a high-power density of 512 W/kg. [ABSTRACT FROM AUTHOR]