High-performance microspherical LiMn_0.5Fe_0.5PO₄ cathodes for structural stability and metal dissolution suppression: Comparison between solvothermal and ball milling synthesis

LiMn_xFe_1–xPO₄ (LMFP) is considered a promising cathode material for lithium-ion batteries, as it retains the safety features of LiFePO₄ while providing higher energy density. However, the intrinsic low electronic conductivity, together with the Mn2+ and Fe2+ oxidation-induced electrolyte decomposition, significantly degrades its practical capacity, rate capability, and cycling stability. This study is conducted to compare the synthesis methods: solvothermal and ball-milling method, to elucidate how route-dependent morphology-controlled affects electrochemical performance and degradation behavior. The optimized composition is obtained by the solvothermal synthesis combined with spray drying (ST-SD) exhibits superior electrochemical performance, delivering initial discharge capacities of 154.91 mAh g−1 at 0.1C and 139.56 mAh g−1 at 1C. After 300 cycles, it retains 76.54% of its initial capacity at 1C. The enhanced performance of the ST-SD sample is associated with its precisely controlled nanorod morphology, which shortens the Li+ diffusion pathways. In contrast, the ball milling synthesis combined with spray drying (BM-SD) delivers initial discharge capacities of 145.24 mAh g−1 at 0.1C and 131.36 mAh g−1 at 1C retaining 66.45% of its initial capacity after 300 cycles. Ex-situ X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) analyses confirm that the ST-SD-derived morphology effectively suppresses metal dissolution and structural degradation caused by side reactions during cycling, thereby improving both the electrochemical performance and structural stability of the LMFP cathode.