Cobalt oxides are technologically important materials, especially when lithiated for application as Li-ion cathodes. However, several phases may crystallize during solid-state synthesis in the Li–Co–O–H system. The solid-state reactions of LiOH·H₂O with both β-Co(OH)₂ and Co₃O₄ have been investigated here through the combined use of high-resolution in situ synchrotron X-ray diffraction (XRD) and Raman spectroscopy, with a special focus on the low-temperature range (RT–600 °C). We show that several spinel phases (AB₂O₄ and A₂B₂O₄ with A, B = Li, Co) are formed in the range 300–525 °C, whose unambiguous identification is only possible through the complementary use of Raman spectroscopy as their XRD patterns are almost identical. While the various structures evidenced are mostly stabilized over similar temperature ranges regardless of the initial choice of Co precursor, the lithiated spinel phases are observed at lower temperatures for samples synthesized from Co(OH)₂. Moreover, their respective Li and Co fractions and crystallinity are strongly affected by the initial choice of precursor. These findings have strong implications in the preparation and optimization of both Co-based cathode active materials and Co-based coatings for other cathode active materials.

中文翻译：

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从 β-Co(OH)2 和 Co3O4 实时结晶 LiCoO2：合成途径和结构演变

钴氧化物在技术上是重要的材料，特别是当锂化用作锂离子阴极时。然而，在 Li-Co-O-H 系统的固态合成过程中，多个相可能会结晶。通过结合使用高分辨率原位同步加速器 X 射线衍射 (XRD) 和拉曼光谱，研究了 LiOH·H ₂ O 与 β-Co(OH) ₂和 Co ₃ O ₄的固态反应, 特别关注低温范围 (RT–600 °C)。我们展示了几个尖晶石相（AB ₂ O ₄和 A ₂ B ₂ O ₄与 A, B = Li, Co) 在 300–525 °C 范围内形成，只有通过互补使用拉曼光谱才能明确识别它们，因为它们的 XRD 模式几乎相同。_{尽管所证明的各种结构在相似的温度范围内大多稳定，而不管 Co 前体的初始选择如何，但对于由 Co(OH) 2}合成的样品，在较低温度下观察到锂化尖晶石相。此外，它们各自的 Li 和 Co 分数和结晶度受到前体初始选择的强烈影响。这些发现对钴基正极活性材料和其他正极活性材料的钴基涂层的制备和优化具有重要意义。