Organic-Inorganic Hybrid Cathode with Dual Energy Storage Mechanism for Ultra-High-Rate and Ultra-Long-Life Aqueous Zinc-Ion Batteries.

The exploitation of cathode materials with high capacity as well as high operating voltage is extremely important for the development of aqueous zinc-ion batteries (ZIBs). Yet the classical high-capacity materials (e.g., vanadium-based materials) provide a low discharge voltage, while organic cathodes with high operating voltage generally suffer from a low capacity. Herein, we design the organic (ethylenediamine) - inorganic (vanadium oxide) hybrid cathodes, i.e., EDA-VO, with dual energy storage mechanism for ultra-high-rate and ultra-long-life ZIBs. The embedded ethylenediamine (EDA) can not only increase the layered spacing of vanadium oxide with improved mobility of Zn ions in V-O layered structure, but also as a bidentate chelating ligand participating in the storage of Zn ions. This hybrid provides a high specific capacity (382 mA h g-1 at 0.5 A g-1 ), elevated voltage (0.82 V) and excellent long-term cycle stability (over 10,000 cycles at 5 A g-1 ). Assistant density functional theory (DFT) calculations indicate the cathode has remarkably electronic conductivity, with an ultralow diffusion barrier of 0.78 eV for optimal Zn ions diffusion path in EDA-VO. This interesting idea of building organic-inorganic hybrid cathode materials with dual energy storage mechanism opens the new research direction towards the high-energy secondary batteries. This article is protected by copyright. All rights reserved.