Impact of Li2CO3–to–LiCl precursor substitution on the electrical properties and Mn3+/Mn4+ redox state of Li2MnO3-based material

Li 2 MnO 3 -based lithium-rich layered oxides are promising high-capacity cathodes for lithium-ion batteries but suffer from structural instability and low conductivity. In this work, Li 2 MnO 3 -based materials were prepared via a high-energy ball milling process using a LiCl-assisted synthesis route. This method involved the partial substitution of Li 2 CO 3 with LiCl (0%, 25% and 50% of Li + supplied by LiCl) Thermal analysis revealed that phase formation initiates near 450 °C, while calcination at 850 °C is required to achieve enhanced crystallinity. Rietveld refinement confirmed the predominant layered Li 2 MnO 3 phase alongside a LiMn 2 O 4 spinel phase that grows with higher LiCl content, indicating modified phase equilibrium. Morphological analysis demonstrated the formation of homogeneous submicrometric particles at 850 °C. Electrical measurements showed enhanced conductivity in LiCl-containing samples, mainly attributed to increased electronic contribution associated with the spinel fraction. EPR spectroscopy confirmed the presence of the Mn 3+ /Mn 4+ redox couple, supporting the correlation between structural modulation and electronic properties.