A novel vanadium coordination supramolecular network with multiple active sites for ultra-durable aqueous zinc metal batteries

Abstract

Aqueous zinc–metal batteries (ZMBs) have stood out from other rechargeable metal batteries due to their high safety, low cost, and stability in neutral electrolytes. However, the capacity decay and sluggish kinetics of the cathode hinder further commercial application of ZMBs. Herein, we construct a novel vanadium coordination supramolecular network (V-CSN) via a facile one-step hydrothermal synthesis, as a cathode for aqueous ZMBs. The multiple active sites and dual energy storage mechanism originate from the redox of the vanadium oxygen center (V⁵⁺/V⁴⁺) and the donors on the ligand (carboxyl group and S atoms), which are synergistically involved in the storage of zinc ions, effectively enhancing the reversible cycle performance. Meanwhile, the large interplanar spacing, small band gap, and flexible CSN structure of V-CSN endowed it with fast kinetics and effectively hinder the dissolution of active materials. Consequently, the V-CSN cathode exhibits an outstanding rate capacity of 177.1 mA h g⁻¹ at 0.2 A g⁻¹ and ultra-long cycle lifespan of over 20 000 cycles at 5 A g⁻¹ with a coulombic efficiency of ∼100 %. Moreover, density functional theory calculations reveal that the cathode has remarkable electrical conductivity and strong adsorption effect with zinc ions (ΔE_ads = −2.9 eV). This work offers a new insight into the construction of a CSN host with abundant active sites, providing a new strategy for the design of high-performance rechargeable aqueous ZMBs.