Coordination Structures\nIntegrating Multiple Redox-Active\nCenters for Enhanced Zinc-Ion Storage

Aqueous zinc-ion batteries (AZIBs) are considered promising\nalternatives\nto lithium-ion batteries (LIBs) owing to their cost efficiency and\neco-friendliness. However, the instability of the electrode materials\nposes a significant obstacle to broader applications. Herein, the\nsynthesis, characterization, and zinc-ion storage properties of a\nvanadium coordination structure (V-INA) that uses VO<sup>2+</sup> as\nthe coordination center and isonicotinic acid (INA) as the organic\nligand have been reported. Characterization techniques confirmed that\nthe spacious lattice spacing and larger pore structure of V-INA create\nan efficient and stable pathway for zinc-ion migration. Note that\nwithin the V-INA structure, both the −COO– and CN\ngroups act in tandem as redox-active centers as well as zinc-ion hosts,\nand the valence change of vanadium (V<sup>4+</sup>/V<sup>5+</sup>)\nin VO<sup>2+</sup> boosts the capacity of the battery. Benefiting\nfrom unique advantages of materials, V-INA achieves an unprecedented\nstability with a capacity retention of 97.25% after 1500 cycles at\n5 A g<sup>–1</sup> as well as still delivers 123 mAh g<sup>–1</sup> reversible capacity after 2000 cycles at 10 A g<sup>–1</sup> with a Coulombic efficiency of ∼100%. This\nwork can inspire the design of coordination structures containing\nmultiple redox-active centers as cathode materials for high-performance\nrechargeable AZIBs.