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<p>Spinel LiNi₀.₅Mn₁.₅O₄ (LNMO) cathode materials suffer from poor interfacial stability, severe discharge capacity fading, and low Li⁺ diffusion rate under high-voltage operation. Herein, a series of Y-F co-doped LNMO materials (LiNi₀.₅₋ₓYₓMn₁.₅O₃.₉₅F₀.₀₅, x = 0, 0.01, 0.03, 0.05) were synthesized via the metal complex polymerization gel (MCPG) method. The synergistic effect of Y-F co-doping on the crystal structure, microstructure, and electrochemical performance was systematically investigated. Through material characterizations including XRD, FTIR, XPS, SEM, EDS, and TEM, a synergistic “dual-directional modulation” mechanism is revealed: Y³⁺ doping expands the lattice parameter and increases Mn³⁺ content, thereby enhancing electronic conductivity; while F⁻ doping forms robust F–Mn bonds that effectively suppress Mn³⁺ disproportionation and dissolution. The results show that LiNi₀.₄₇Y₀.₀₃Mn₁.₅O₃.₉₅F₀.₀₅ (0.03YF) effectively suppresses the formation of LiₓNi₁₋ₓO impurity phase, induces an increase in lattice parameters, enhances cation disorder degree, and raises Mn³⁺ content. Moreover, it promotes the morphological transformation of crystal particles from regular octahedra to truncated octahedra, exposing more highly active {100} crystal facets. Electrochemical test results demonstrate that the 0.03YF sample delivers an initial discharge capacity of 132 mAh/g at 1&#xa0;C, maintains a high capacity retention of 93.9% after 200 cycles, and still retains 81.8% of its capacity at a high rate of 10&#xa0;C. The Li⁺ diffusion coefficient calculated from CV measurements reaches 10.55 × 10⁻¹² cm²/s, which is 73% higher than that of the pristine sample. EIS tests show that the charge-transfer resistance (Rct) is substantially reduced from 95.3 Ω to 41.5 Ω, leading to significantly decreased electrode polarization. Y-F co-doping possesses unique advantages in simultaneously optimizing the bulk structure and the electrode/electrolyte interface, offering a promising strategy for advancing the practical application of high-voltage LNMO cathode materials.</p>

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Synergistic effect of Y-F co-doping on interfacial stability and Li⁺ diffusion kinetics in LiNi0.5Mn1.5O4 cathode materials for high-performance lithium-ion batteries

  • 期刊论文

  • 发表日期：

    2026年7月23日

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  • ZhenDe Huang,
  • Di Peng

摘要

Spinel LiNi₀.₅Mn₁.₅O₄ (LNMO) cathode materials suffer from poor interfacial stability, severe discharge capacity fading, and low Li⁺ diffusion rate under high-voltage operation. Herein, a series of Y-F co-doped LNMO materials (LiNi₀.₅₋ₓYₓMn₁.₅O₃.₉₅F₀.₀₅, x = 0, 0.01, 0.03, 0.05) were synthesized via the metal complex polymerization gel (MCPG) method. The synergistic effect of Y-F co-doping on the crystal structure, microstructure, and electrochemical performance was systematically investigated. Through material characterizations including XRD, FTIR, XPS, SEM, EDS, and TEM, a synergistic “dual-directional modulation” mechanism is revealed: Y³⁺ doping expands the lattice parameter and increases Mn³⁺ content, thereby enhancing electronic conductivity; while F⁻ doping forms robust F–Mn bonds that effectively suppress Mn³⁺ disproportionation and dissolution. The results show that LiNi₀.₄₇Y₀.₀₃Mn₁.₅O₃.₉₅F₀.₀₅ (0.03YF) effectively suppresses the formation of LiₓNi₁₋ₓO impurity phase, induces an increase in lattice parameters, enhances cation disorder degree, and raises Mn³⁺ content. Moreover, it promotes the morphological transformation of crystal particles from regular octahedra to truncated octahedra, exposing more highly active {100} crystal facets. Electrochemical test results demonstrate that the 0.03YF sample delivers an initial discharge capacity of 132 mAh/g at 1 C, maintains a high capacity retention of 93.9% after 200 cycles, and still retains 81.8% of its capacity at a high rate of 10 C. The Li⁺ diffusion coefficient calculated from CV measurements reaches 10.55 × 10⁻¹² cm²/s, which is 73% higher than that of the pristine sample. EIS tests show that the charge-transfer resistance (Rct) is substantially reduced from 95.3 Ω to 41.5 Ω, leading to significantly decreased electrode polarization. Y-F co-doping possesses unique advantages in simultaneously optimizing the bulk structure and the electrode/electrolyte interface, offering a promising strategy for advancing the practical application of high-voltage LNMO cathode materials.