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Thermal stress-induced charge and structure heterogeneity in emerging cathode materials
Materials Today ( IF 21.1 ) Pub Date : 2020-05-01 , DOI: 10.1016/j.mattod.2019.11.009
Judith Alvarado , Chenxi Wei , Dennis Nordlund , Thomas Kroll , Dimosthenis Sokaras , Yangchao Tian , Yijin Liu , Marca M. Doeff

Abstract Nickel-rich layered oxide cathode materials are attractive near-term candidates for boosting the energy density of next generation lithium-ion batteries. The practical implementation of these materials is, however, hindered by unsatisfactory capacity retention, poor thermal stability, and oxygen release as a consequence of structural decomposition, which may have serious safety consequences. The undesired side reactions are often exothermic, causing complicated electro-chemo-mechanical interplay at elevated temperatures. In this work, we explore the effects of thermal exposure on chemically delithiated LiNi0.8Mn0.1Co0.1O2 (NMC-811) at a practical state-of-charge (50% Li content) and an over-charged state (25% Li content). A systematic study using a suite of advanced synchrotron radiation characterization tools reveals the dynamics of thermal behavior of the charged NMC-811, which involves sophisticated structural and chemical evolution; e.g. lattice phase transformation, transition metal (TM) cation migration and valence change, and lithium redistribution. These intertwined processes exhibit a complex 3D spatial heterogeneity and, collectively, form a valence state gradient throughout the particles. Our study sheds light on the response of NMC-811 to elevated temperature and highlights the importance of the cathode’s thermal robustness for battery performance and safety.

中文翻译:

新兴正极材料中的热应力诱导电荷和结构异质性

摘要 富镍层状氧化物正极材料是提高下一代锂离子电池能量密度的近期候选材料。然而,这些材料的实际应用受到不令人满意的容量保持率、较差的热稳定性和结构分解导致的氧气释放的阻碍,这可能会产生严重的安全后果。不需要的副反应通常是放热的,在升高的温度下会导致复杂的电化学机械相互作用。在这项工作中,我们探索了热暴露对实际充电状态(50% Li 含量)和过充电状态(25% Li)下化学脱锂的 LiNi0.8Mn0.1Co0.1O2 (NMC-811) 的影响。内容)。使用一套先进的同步辐射表征工具进行的系统研究揭示了带电 NMC-811 的热行为动力学,其中涉及复杂的结构和化学演化;例如晶格相变、过渡金属 (TM) 阳离子迁移和价态变化以及锂重新分布。这些交织在一起的过程表现出复杂的 3D 空间异质性,并共同形成整个粒子的价态梯度。我们的研究阐明了 NMC-811 对高温的响应,并强调了阴极热稳定性对电池性能和安全性的重要性。和锂再分布。这些交织在一起的过程表现出复杂的 3D 空间异质性,并共同形成整个粒子的价态梯度。我们的研究阐明了 NMC-811 对高温的响应,并强调了阴极热稳定性对电池性能和安全性的重要性。和锂再分布。这些交织在一起的过程表现出复杂的 3D 空间异质性,并共同形成整个粒子的价态梯度。我们的研究阐明了 NMC-811 对高温的响应,并强调了阴极热稳定性对电池性能和安全性的重要性。
更新日期:2020-05-01
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