Solution combustion synthesis f P2-Na0.71CoO2 using a cellulose- derivative 2D HEC–EDTA chelating precursor

Layered sodium transition-metal oxides are promising materials for sodium-ion battery cathodes, but their synthesis requires careful control of phase purity, Na/Co stoichiometry, and chemical homogeneity. In this work, a cellulose- derivative 2D HEC–EDTA chelating precursor was used as a structured coordination platform for the solution combustion synthesis of layered P2-Na 0.71 CoO 2 . The HEC–EDTA network acts simultaneously as a metal-ion chelating medium, spatial stabilizer, and fuel source, enabling homogeneous distribution of Na + and Co 2+ ions before thermal treatment. The P2-Na 0.71 CoO 2 phase was obtained after calcination at 700 °C for 3 h and was confirmed by X-ray diffraction, Rietveld refinement, ICP-AES, ATR-FTIR, Raman spectroscopy, SEM-EDX, and thermal analysis. Structural refinement confirmed the formation of a hexagonal type P2-Na 0.71 CoO 2 structure, while SEM revealed a nanosheet-like agglomerate morphology. The crystallite size was estimated to be approximately 34 nm, and thermal analysis indicated good thermal stability with no residual organic species. Molecular dynamics simulations, electrostatic potential surface analysis, and radial distribution functions further supported the role of electrostatic and coordination interactions between Na + / Co 2+ ions and the carboxylate/amine groups of the HEC-EDTA precursor. This study demonstrates that cellulose- derivative chelating polymer precursors provide an effective route for improving metal-ion distribution, stoichiometric control, and phase formation in layered transition-metal oxide synthesis.