Achieving ultralong lifespan and low-temperature adaptability in aqueous zinc-ion batteries via fluorinated organic molecule-intercalated vanadium oxide.

Aqueous zinc-ion batteries (AZIBs) are highly promising for large-scale energy storage applications due to their high safety, low cost, and environmental friendliness. Vanadium-based materials deliver outstanding specific capacities, rendering α-V2O5 a highly competitive precursor candidate for such batteries. However, vanadium-based materials suffer from dissolution loss in electrolytes, slow ion diffusion kinetics, and substantial voltage hysteresis. They accumulate at the electrode-separator interface, block ion transport channels, and significantly increase cell internal resistance. This work proposes a multifunctional doping strategy based on 3-fluoroisonicotinic acid to overcome this critical bottleneck. The 3-fluoroisonicotinic acid doped α-V2O5 composite (α-V2O5-F) and its counterpart, the 3-chloroisonicotinic acid doped product (α-V2O5-Cl) were successfully synthesized through a two-step hydrothermal route. By stimulating molecular-level synergy, 3-fluoroisonicotinic acid better integrates into V2O5, thereby enlarges the interlayer spacing and improves ion diffusion and electronic conductivity. The composite, when modified, serves as a cathode for AZIBs, delivering excellent specific capacity and extended cycling stability. The reversible discharge capacity of 478.6 mAh g-1 at 0.2 A g-1 represents a notable improvement over the pristine α-V2O5. A capacity of 276.8 mAh g-1 is retained at 4.0 A g-1, with a 72.3% retention rate after 3000 cycles, reflecting superior structural robustness and electrochemical durability. It provides an effective and feasible route for the development and design of high-performance cathode materials for AZIBs using molecular-level doping modification.