Electrochemical performance of hydrothermally synthesized manganese dioxide as anode for lithium-ion batteries

Three types of manganese dioxide with distinct morphologies were synthesized via a hydrothermal method. The phase composition, crystal structure, surface morphology, specific surface area, pore size parameters, oxygen vacancy content, and electrochemical properties of the samples were systematically characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (SEM), N₂ adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), and electrochemical tests. The results revealed that the synthesized manganese dioxide samples belonged to the tetragonal α-MnO₂ phase but exhibited different morphologies, specific surface areas, and oxygen vacancy contents (urchin-like > needle-like > fiber-like). Electrochemical performance tests demonstrated that the urchin-like MnO₂ delivered a high reversible capacity (315 mAh g⁻¹ after 60 cycles at 100 mA g⁻¹), Coulombic efficiency (>99 %), superior rate capability, and excellent cycling stability. The enhanced electrochemical performance of urchin-like MnO₂ is attributed to its high oxygen vacancy content, which improves charge transfer kinetics and provides additional active sites for lithium-ion storage, making it a promising anode material for lithium-ion batteries.