Hydroxyethyl Cellulose-Intercalated Vanadium Oxide Cathodes with Lattice Defect Engineering for High-Performance Aqueous Zinc-Ion Batteries.

To address the structural instability and rapid capacity fading of the cathodes for aqueous zinc-ion batteries (AZIBs), a composite cathode material noted as VO-i-HEC is fabricated in this work by the intercalation of hydroxyethyl cellulose (HEC) into layered vanadium pentoxide (VO). The electrostatic interactions from the polar functional groups of HEC expand the interlayer spacing of VO from 4.3 to 12.74 Å and cleave V─O─V bridging bonds, resulting in high-density lattice defects within VO-i-HEC. The structural modifications synergistically create pathways for rapid Zn diffusion and introduce additional redox-active sites in VO-i-HEC as well. As a result, VO-i-HEC achieves a high specific capacity of 499.88 mAh·g⁻ at 0.1 A·g and demonstrates remarkable stability over 2000 cycles at 10 A·g, with a low capacity decay rate of 0.004%. Differential charge density analysis and density functional theory calculations reveal that HEC intercalation enhances electron delocalization, reduces Zn migration barriers from 0.74 to 0.14 eV, and suppresses parasitic reactions, proving that the structure-interface synergistic regulation strategy is a highly effective design paradigm for vanadium-based cathodes in high-performance AZIBs.