Metal–organic cathode compounds with low solubility and more viable eco-efficient production still suffer from relatively low voltage and limited discharge capacity because their redox reactions solely rely on active organic functional groups or metal clusters.
A metal–organic compound Cu2(p-O2NC6H4CO2)4(EtO)2 was demonstrated to have high capacity of 243 mA h g–1 and high-voltage plateaus of 3.66, 3.15, 2.25, and 2.08 V vs Li+/Li through first-principles calculations. Electronic structure analysis reveals Cu2+ ↔ Cux+ (1 < x < 2) and Oy– (1 < y < 2) ↔ O2– in a metal–ligand moiety and N5+ ↔ Nx+ (4 < x < 5) and O2– ↔ Oz– (1 < z < 2) in −NO2 groups, achieving high voltage and capacity by operating cooperative cationic–anionic redox reactions based on multiple active sites and hierarchical chemical bonds. Furthermore, the Cu2(p-O2NC6H4CO2)4(EtO)2 is also predicted to have good electrochemical reversibility because the cationic conversion reaction is inhibited by a higher-voltage anionic reaction and hierarchical chemical bonds of [MO5]n−. The study provides a strategy to design metal–organic cathode compounds with high performance.
The study was published in ACS Energy Lett. PhD student ZHAO Xiaolin at University of Chinese Academy of Sciences is the first author.
