Metal-Organic Framework/Layered Carbon Nitride Nano–sandwiches for Superior Asymmetric Supercapacitor

The Fe-doped Zeolitic Imidazolate Frameworks/layered CN nano-sandwiches (Fe-ZIF/CN) and porous C/layered CN nano-sandwiches (porous C/CN) were synthesized from a single Metal-Organic Frameworks/layered CN nano-sandwich precursor. The Fe-ZIF/CN and porous C/CN electrode possessed high specific surface area for 1609 and 2048 m²⋅g⁻¹ respectively and they showed high capacitance values for 1096 and 587 F⋅g⁻¹ at the current density of 1 A g⁻¹ under three electrode configuration. The electrochemical performance and stable potential windows of the asymmetric supercapacitors (ASCs) based on FeZIF/CN nano-sandwiches (positive electrode) and porous C/CN (negative electrode) were further evaluated. The high energy density supercapacitor was successfully realized by the appliances (Fe-ZIF/CN//porous C/CN), much better than those of the SSCs based on porous C/CN or Fe-ZIF/CN electrode materials. The advanced ASCs could work within a wide potential window of 0–1.6 V, which contributed to a high specific energy density of 153 W⋅h⋅kg⁻¹. The superior performance was ascribed to the high capacitance and the positive synergistic effects of the two electrodes. These encouraging results revealed a potential in exploiting energy storage appliance with high energy density and power density appliance for practical applications.