Whba, RawdahDogan, EbruDuygulu, OzgurAlanazi, Abdullah K.Arshad, MuhammadStoyanova, RadostinaKoleva, Violeta2026-04-042026-04-0420252566-6223https://doi.org/10.1002/batt.202500680https://hdl.handle.net/11616/110002This article explores the synthesis and electrochemical properties of NaxMn0.5Fe0.5O2 powders, prepared via a conventional solid-state reaction. Subsequently, the powders are functionalized with a ZnO protective coating through a wet-chemical approach employing zinc acetate in ethanol. Structural characterization confirmed that the ZnO layer maintained the P2-type (P6 3 /mmc) structure, while energy-dispersive X-ray spectrometry mapping verified the successful coating. Electrochemical analyses, including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry, revealed that although the redox reaction mechanism remained unchanged, the charge-transfer resistance (R ct) depended on the coating thickness. ZnO-coated NMFO electrodes exhibited initial discharge capacities of 159.3, 153.6, and 124.8 mAh g- 1 with respective capacity retentions of 48.9%, 41.9%, and 52.0% after 100 cycles for ZnO contents of 0.2, 0.4, and 0.6 wt.%. The galvanostatic intermittent titration technique results indicated that the diffusion coefficients varied with the coating conditions. Operando EIS from 1.5 to 4.3 V showed stable bulk resistance (R b) but voltage-dependent variations in solid electrolyte interface resistance (R SEI) and R ct. Additionally, sodium azide is used to presodiate the hard carbon (HC) anode to enhance the full-cell performance. The ZnO-coated cathode paired with NaN3 presodiated HC delivered a capacity of over 120 mAh g- 1 at C/10. Ex situ analysis after 500 cycles confirmed structural stability, demonstrating that ZnO coating and NaN3 presodiation collectively improve sodium-ion battery performance.eninfo:eu-repo/semantics/openAccesshard carbonP2-type cathode materialsodium azidesodium-ion batteriesZnO coatingArticle10.1002/batt.2025006802-s2.0-105022206128Q1WOS:001617475200001Q20000-0002-4590-907X0000-0001-8646-0363