This study examines the role of defects in structure–property relationships in spinel LiMn_1.5Ni_0.5O₄ (LMNO) cathode materials, especially in terms of Mn³⁺ content, degree of disorder, and impurity phase, without the use of the traditional high-temperature annealing (≥700 °C used for making disordered LMNO). Two different phases of LMNO (i.e., highly P4₃32-ordered and highly Fd3̅m-disordered) have been prepared from two different β-MnO_2−δ precursors obtained from an argon-rich atmosphere (β-MnO_2−δ (Ar)) and a hydrogen-rich atmosphere [β-MnO_2−δ (H₂)]. The LMNO samples and their corresponding β-MnO_2−δ precursors are thoroughly characterized using different techniques including high-resolution transmission electron microscopy, field-emission scanning electron microscopy, Raman spectroscopy, powder neutron diffraction, X-ray photoelectron spectroscopy, synchrotron X-ray diffraction, X-ray absorption near-edge spectroscopy, and electrochemistry. LMNO from β-MnO_2−δ (H₂) exhibits higher defects (oxygen vacancy content) than the one from the β-MnO_2−δ (Ar). For the first time, defective β-MnO_2−δ has been adopted as precursors for LMNO cathode materials with controlled oxygen vacancy, disordered phase, Mn³⁺ content, and impurity contents without the need for conventional methods of doping with metal ions, high synthetic temperature, use of organic compounds, postannealing, microwave, or modification of the temperature-cooling profiles. The results show that the oxygen vacancy changes concurrently with the degree of disorder and Mn³⁺ content, and the best electrochemical performance is only obtained at 850 °C for LMNO-(Ar). The findings in this work present unique opportunities that allow the use of β-MnO_2−δ as viable precursors for manipulating the structure–property relationships in LMNO spinel materials for potential development of high-performance high-voltage lithium-ion batteries.

中文翻译：

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缺陷工程 β-MnO2−δ 前驱体控制高压尖晶石 LiMn1.5Ni0.5O4−δ 的结构-性能关系

本研究考察了缺陷在尖晶石 LiMn _1.5 Ni _0.5 O ₄ (LMNO) 正极材料结构-性能关系中的作用，特别是在 Mn ³⁺含量、无序度和杂质相方面，而不使用传统的高- 温度退火（≥700 °C 用于制造无序 LMNO）。两种不同的 LMNO 相（即高度P 4 ₃ 32 有序和高度Fd 3̅ m无序）已经从富氩气氛中获得的两种不同的 β-MnO _2-δ前体（β-MnO _2-δ (Ar)) 和富氢气氛 [β-MnO _2−δ (H₂ )]。LMNO 样品及其相应的 β-MnO _2-δ前驱体使用不同的技术进行彻底表征，包括高分辨率透射电子显微镜、场发射扫描电子显微镜、拉曼光谱、粉末中子衍射、X 射线光电子能谱、同步加速器 X-射线衍射、X 射线吸收近边光谱和电化学。来自β-MnO _2-δ (H ₂ ) 的LMNO表现出比来自β-MnO _2-δ (Ar) 的LMNO更高的缺陷（氧空位含量）。有缺陷的β-MnO _2-δ首次被用作具有可控氧空位、无序相、Mn ^{3+ 的}LMNO正极材料的前驱体无需使用掺杂金属离子、高合成温度、使用有机化合物、后退火、微波或修改温度冷却曲线的常规方法即可获得更高的含量和杂质含量。结果表明，氧空位随无序度和Mn ³⁺含量的变化而变化，LMNO-(Ar)仅在850 °C时获得最佳电化学性能。这项工作的发现提供了独特的机会，允许使用 β-MnO _2-δ作为可行的前体来操纵 LMNO 尖晶石材料中的结构 - 性能关系，以开发高性能高压锂离子电池。