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 (V₂O₅). The electrostatic interactions from the polar functional groups of HEC expand the interlayer spacing of V₂O₅ from 4.3 to 12.74 Å and cleave V─O₍₂₎─V bridging bonds, resulting in high-density lattice defects within VO-i-HEC. The structural modifications synergistically create pathways for rapid Zn²⁺ 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⁻¹ at 0.1 A·g^-1 and demonstrates remarkable stability over 2000 cycles at 10 A·g^-1, 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 Zn²⁺ 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.