Oxygen-deficient amorphous manganese oxide was synthesized and explored for the first time as a cathode material for aqueous zinc–MnO₂ batteries delivering high specific capacity.

The chemical exfoliation of graphite to produce graphene and its oxide is undoubtedly an economical method for scalable production. Carbon researchers have dedicated significant resources to developing new exfoliation methods leads to graphene oxides with high quality. However, only a few studies have been dedicated to the effect of the starting graphite material on the resulting GO. Herein, we have prepared two different GOs through chemical exfoliation of graphite materials having different textural and structural characteristics. All samples have been subjected to structural investigations and comprehensive characterizations using Raman, X-ray diffraction, scanning electron microscopy, TGA, N₂ physisorption, and FTIR spectroscopy. Our results provide direct evidence of how the crystallite size of the raw graphite affects the oxidation degree, surface functionality, and sheet size of the resulting GO. Building on these significant understandings, the optimized GO achieves a highly specific capacitance of 191 F·g⁻¹ at the specific current of 0.25 A·g⁻¹ in an aqueous electrolyte. This superior electrochemical performance was attributed to several factors, among which the specific surface area was accessible to the electrolyte ions and oxygenated functional groups on the surface, which can significantly modify the electronic structure of graphene and further enhance the surface energy.

The link between MnO ₂ precursors and LiMn ₂ O ₄ cathodes is shown, with precursor properties influencing spinel formation, stability, and performance. Operando XRD and ARC highlight the structural and cycling stability for eco-friendly energy storage.