Quinone-Based Conducting Three-Dimensional Metal–Organic Framework as a Cathode Material for Lithium-Ion Batteries

The low electronic conductivity of organic electrode materials leads to sluggish reaction kinetics and inferior electrochemical performance of lithium-ion batteries. Herein, the conducting three-dimensional metal–organic framework (3D-MOF) (NBu4)2Fe2(DHBQ)3 was synthesized through a facile aqueous addition reaction. The intramolecular charge delocalization through the robust π–d conjugation between DHBQ ligands and Fe3+ centers is favorable for long-range electron migration, resulting in high electronic conductivity of the 3D hollow (NBu4)2Fe2(DHBQ)3. When applied as the cathode material, (NBu4)2Fe2(DHBQ)3 delivers a reversible capacity of 137.2 mA h g–1 at 10 mA g–1 and 95.2 mA h g–1 at 1000 mA g–1. The capacity retention reached up to 91.4% after 350 cycles at 500 mA g–1 with about 100% Coulombic efficiency. Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy tests reveal that the conjugated carbonyls of DHBQ organic linkers contribute the redox centers and undergo a 5e– reaction mechanism during charge and discharge processes. These excellent electrochemical performances could be attributed to the fast electron/ion migration kinetics because of high electronic conductivity and the hollow structure of (NBu4)2Fe2(DHBQ)3. All the positive results could facilitate the implementation of conductive MOFs for energy conversion and storage acceleration.