中国科学院物理研究所苏东团队近日研究了富锂锰阴极化学分离的两相结构。2025年5月21日出版的《国家科学评论》杂志发表了这项成果。

富锰锂（LMR）氧化物被认为是下一代电池最有前途的正极材料之一。然而，它们在循环过程中的低速率性能和性能下降对实际应用提出了重大挑战。了解如何在合成过程中优化其微观结构可能为提高它们的性能提供关键的见解。

研究组分析了Li-/Mn-/Ni-carbonate前驱体在固态烧结Li_1.2Ni_0.2Mn_0.6O₂过程中的结构演变。结合X射线衍射和透射电子显微镜（TEM）技术，研究人员观察到550°C时纳米级固溶相的成核，伴随着尖晶石样、层状和岩盐的次生相。在800℃时，相对纯净的固溶相R3M形成了。

值得注意的是，当样品从850°C退火到900°C时，研究组首次发现了从固溶结构到化学分离的两相结构的相变。原子分辨率扫描TEM（STEM）成像清楚地区分了C2/m相和R3m相，由相干晶界隔开，STEM能量色散光谱（STEM-EDS）映射证实了这一点。

该计算表明，高温活化引起的Ni²⁺离子的扩散在促进相分离方面起着重要作用。与之前报道的纳米级两相结构相比，相对较大的化学分离两相结构预计将表现出不同的性能特征，为进一步改进高能量密度LMR阴极提供了新的基础。

附：英文原文

Title: Revealing the chemical separated two-phase structure in lithium-manganese-rich cathode

Author: Wang, Jiayi, Lei, Xincheng, Meng, Hao, Ji, Pengxiang, Lu, Tenglong, Liang, Weijun, Liu, Xiaozhi, Meng, Sheng, Gu, Lin, Liu, Miao, Wang, Xin, Su, Dong

Issue&Volume: 2025-05-21

Abstract: Lithium-manganese-rich (LMR) oxides are regarded as one of the most promising cathode materials for next-generation batteries. However, their poor rate capability and performance degradation during cycling present significant challenges for practical applications. Understanding how to optimize their microscopic structures during synthesis may provide critical insights for enhancing their performance. In this work, we investigated the structural evolution during the solid-state sintering of Li1.2Ni0.2Mn0.6O2 from Li-/Mn-/Ni-carbonate precursors. Combining X-ray diffraction and transmission electron microscopy (TEM) techniques, we observed the nucleation of a nanoscaled solid-solution phase at 550°C, accompanied by secondary phases of spinel-like, layered and rocksalt. At 800°C, a relatively pure solid-solution phase R3m is formed. Notably, we uncovered, for the first time, a phase transition from solid-solution structure to chemically separated two-phase structure when annealing the sample from 850°C to 900°C. Atomic resolution scanning-TEM (STEM) imaging clearly distinguished the C2/m phase from the R3m phase, separated by a coherent grain boundary, as confirmed by STEM-energy-dispersion spectroscopy (STEM-EDS) mapping. Our calculations indicate that the diffusion of Ni2 ions induced by high-temperature activation plays a significant role in facilitating the phase separation. The relatively large chemically separated two-phase structure is expected to exhibit different performance characteristics compared to the previously reported nanosized two-phase structures, providing a new foundation for further improving high-energy-density LMR cathodes.

DOI: 10.1093/nsr/nwaf202

Source: https://academic.oup.com/nsr/advance-article/doi/10.1093/nsr/nwaf202/8140057searchresult=1