Dogan, EbruMaiga, AbdulhadiWhba, RawdahHarfouche, MessaoudOzturk, Zeynep ReyhanFarhan, AhlamAltin, Emine2026-04-042026-04-0420260378-77531873-2755https://doi.org/10.1016/j.jpowsour.2025.238602https://hdl.handle.net/11616/109513The structural instability and moderate electrochemical performance of NaMnO2 cathodes limit the use of sodium-ion batteries (SIBs). This limitation is primarily due to lattice distortions and valence variations that occur during the cycling process. To address this limitation, NaMn(1-x)FexO(2) (0.00 <= x <= 0.50) powders were synthesized using a conventional solid-state method. Their structural and electrochemical properties were systematically investigated through a combination of structural characterization, in situ X-ray absorption spectroscopy, and computational modeling. X-ray diffraction and Rietveld refinement reveal a contraction of the beta-angle from 112 degrees to 105 degrees, indicative of a phase transition from alpha to alpha', with the x = 0.5 composition stabilizing as a single-phase alpha' structure. Fe incorporation reduces the average Mn valence from 3.23+ to 3.18+, thereby enhancing structural stability, as corroborated by electron diffraction and density functional theory (DFT) calculations. At the same time, hard carbon (HC) derived from chestnut shells was developed as a sustainable anode material, exhibiting a disordered framework favorable for Na+ storage. Electrochemical evaluation demonstrates that the x = 0.5 cathode delivers an initial half-cell capacity of 130.2 mAh/g, which declines to 77.1 mAh/g upon cycling. In contrast, the optimized electrode configuration affords improved stability. The HC anode attains a high reversible capacity of 317.3 mAh/g. Full-cell assemblies incorporating pre-sodiated HC anodes exhibit promising performance, underscoring the potential of this dual-material approach for developing high-performance, sustainable SIBs.eninfo:eu-repo/semantics/closedAccessNa-ion batteryCathode materialsNaMnO2Fe-dopingStructural propertiesElectrochemical performanceArticle66110.1016/j.jpowsour.2025.2386022-s2.0-105019956305Q1WOS:001612023300006Q10009-0005-6858-80600000-0002-4786-897X0000-0001-8009-51580000-0001-8646-03630000-0003-4103-9510