Conjugated Copper-Catecholate Framework Electrodes for Efficient Energy Storage

Abstract

A conjugated copper(II) catecholate based metal-organic framework (namely Cu-DBC) was prepared using a D₂ -symmetric redox-active ligand in a copper bis(dihydroxy) coordination geometry. The π-d conjugated framework exhibits typical semiconducting behavior with a high electrical conductivity of ca. 1.0 S m^-1 at room temperature. Benefiting from the good electrical conductivity and the excellent redox reversibility of both ligand and copper centers, Cu-DBC electrode features superior capacitor performances with gravimetric capacitance up to 479 F g^-1 at a discharge rate of 0.2 A g^-1 . Moreover, the symmetric solid-state supercapacitor of Cu-DBC exhibits high areal (879 mF cm^-2 ) and volumetric (22 F cm^-3 ) capacitances, as well as good rate capability. These metrics are superior to most reported MOF-based supercapacitors, demonstrating promising applications in energy-storage devices.

Keywords: catecholate; copper; metal-organic frameworks; semiconductors; supercapacitors.