A Rationally Designed Iron–Dihydroxybenzoquinone Metal–Organic Framework as Practical Cathode Material for Rechargeable Batteries

Abstract

Metal–organic frameworks (MOFs) are regarded as promising cathode materials for rechargeable Li and Na batteries, but suffering from low energy density and high cost. Herein, we have successfully synthesized a novel and low-cost MOF based on the coordination between Fe3+ and 2,5-dihydroxybenzoquinone (DHBQ) ligand, namely Fe2(DHBQ)3. Compared to its analogues, the rational structure provides it with much higher average discharge voltage (2.43 V vs. Li+/Li) and reversible capacity (285 mAh g–1), leading to the highest Li-storage energy density (693 Wh kg–1) among all MOF-type cathodes. Besides, Fe2(DHBQ)3 also exhibits outstanding electronic conductivity (1.1 × 10–4 S cm–1), rate capability (57% @ 5000 mA g–1), and long-term cycling stability (90% @ 1000th cycle), as well as good applicability to practical test conditions and Na batteries. Moreover, the redox reaction and electrode evolution mechanisms were clearly investigated, providing significant insights in this field.