Morphologies of thienyl based bimetallic metal-organic frameworks controlled by solvents for high specific capacitance supercapacitor

Abstract Metal-organic frameworks(MOF) is a promising energy storage material, but its low electron transmission efficiency and low energy density hinder its application as a high-performance supercapacitor electrode material. Here, we show a Ni/Co bimetallic MOF electrode based on thiophene ligand with diverse morphologies from solvothermal method utilized different solvents. The results showed that the morphology of thienyl based Ni/Co MOF gradually changes from a spherical structure to a flaky structure as the degree of solvent protonation increases. Compared with other MOFs synthesized by low protonation solvent, thienyl based Ni/Co MOF with a sheet-like structure synthesized by ethanol provides more paths for electron transport between layers, and more activity for ion migration on the electrode surface site, ensuring a higher charge storage capacity. The electrochemical performance of thienyl based Ni/Co MOF as supercapacitor electrode materials in 1 M KOH was assessed, and it is found that when the current density is 1 A g−1, the maximum specific capacitance of thienyl based Ni/Co MOF(synthesized by ethanol) is 1282 F g−1, and the capacitance retention rate of asymmetric supercapacitor device assembled by thienyl based Ni/Co MOF(synthesized by ethanol) is about 73.6% even after 10,000 cycles, meaning that thienyl based Ni/Co MOF(synthesized by ethanol) is a promising electrode material for supercapacitors.