Effect of Mo6+doping on the structure and electrochemical properties of spinel-type LiMn2O4 cathode materials

The Jahn-Teller effect and the dissolution of Mn are significant factors contributing to the capacity degradation of spinel LiMn2O4 cathode materials during charging and discharging. In this study, Mo6 & thorn;doped polycrystalline octahedral Li1.05Mn2-xMoxO4 (x = 0, 0.005, 0.01, 0.015) cathode materials were prepared by simple solid-phase sintering, and their crystal structures, microscopic morphologies, and elemental compositions were characterized and analyzed. The results showed that the doping of Mo6+ promoted the growth of (111) crystalline facets and increased the ratio of Mn3+/Mn4+. The electrochemical performance of the materials was also tested, revealing that the doping of Mo6+ significantly improved the initial charge/discharge specific capacity and cycling stability. The modified sample (LMO0.01Mo) retained a reversible capacity of 114.83 mA h/g with a capacity retention of 97.29% after 300 cycles. Additionally, the doping of Mo6+ formed a thinner, smoother SEI film and effectively inhibited the dissolution of Mn. Using density-functional theory (DFT) calculations to analyze the doping mechanism, it was found that doping shortens the Mn-O bond length inside the lattice and increases the Li-O bond length. This implies that the Li & thorn; diffusion channel is widened, thereby increasing the Li & thorn; diffusion rate. Additionally, the modification reduces the energy band gap, resulting in higher electronic conductivity. (c) 2024 Chinese Society of Particuology and Institute of Process Engineering, Chinese Academy of Sciences. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.