Dual-Ion-Modulated Vanadium Oxide Cathode for High-Performance Aqueous Zinc-Ion Batteries

Developing cathode materials with superior ion transport kinetics and stable crystalline frameworks has emerged as a critical challenge in advancing aqueous zinc-ion batteries (AZIBs) technology. In this work, a series of transition metal ion M (M = Sn, Cr, Cu, Co, Ni) and sulfur codoped V₂O₃-based composites with three-dimensional flower-like morphology, denoted as (M, S)V₂O_3-<i>x</i>, were synthesized via an <i>in situ</i> metal-organic framework-templated doping strategy. The (Sn, S)V₂O_3-<i>x</i> demonstrates superior electrochemical performance through synergistic structural modifications. Sn doping enables morphological regulation, forming a hierarchical three-dimensional flower-like architecture with abundant mesopores and a large specific surface area. This configuration not only shortens Zn²⁺ migration pathways but also mitigates the loss of reactive active sites caused by particle agglomeration during electrochemical cycling. Sulfur doping enhances oxygen defect concentration in the host lattice, creating additional Zn²⁺ transport channels and promoting ionic diffusion kinetics. The lower electronegativity of sulfur relative to oxygen alleviates localized stress accumulation during phase transitions, thereby improving the structural resilience of the resultant phases. These coordinated effects endow the (Sn, S)V₂O_3-<i>x</i> with exceptional properties, including high capacity and long-term cycling stability. The results showed that the discharge capacity of (Sn, S)V₂O_3-<i>x</i> electrode was 552.52 mAh g^-1 at 0.1 A g^-1 current density; the initial discharge capacity was 353.93 and 345.83 mAh g^-1 at 10.0 and 20.0 A g^-1 current densities, and the capacity retention after 2000 cycles was 97.25% and 94.25%, respectively. In comparison, V₂O₃ delivers a capacity of only 429.30 mAh g^-1 at a current density of 0.1 A g^-1. Its initial discharge capacities at 10.0 and 20.0 A g^-1 are 204.24 and 135.96 mAh g^-1, respectively, with capacity retention rates of 49.53% and 60.04% after 2000 cycles. This work advances high-energy-density AZIBs through a synergistic strategy integrating "morphological engineering-bond strength modulation-phase transition stabilization".