Goonetilleke Damian, Suard Emmanuelle, Bergner Benjamin, Janek Jürgen, Brezesinski Torsten, Bianchini Matteo
Battery and Electrochemistry Laboratory (BELLA), Institute of Nanotechnology, Karlsruhe Institute of Technology (KIT), Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany.
Institut Laue-Langevin (ILL), BP 156, 71 Avenue des Martyrs, 38042 Grenoble, France.
J Appl Crystallogr. 2023 Jun 23;56(Pt 4):1066-1075. doi: 10.1107/S1600576723004909. eCollection 2023 Aug 1.
Studying chemical reactions in real time can provide unparalleled insight into the evolution of intermediate species and can provide guidance to optimize the reaction conditions. For solid-state synthesis reactions, powder diffraction has been demonstrated as an effective tool for resolving the structural evolution taking place upon heating. The synthesis of layered Ni-rich transition-metal oxides at a large scale (grams to kilograms) is highly relevant as these materials are commonly employed as cathodes for Li-ion batteries. In this work, neutron diffraction was used to monitor the reaction mechanism during the high-temperature synthesis of Ni-rich cathode materials with a varying ratio of Ni:Mn from industrially relevant hydroxide precursors. Rietveld refinement was further used to model the observed phase evolution during synthesis and compare the behaviour of the materials as a function of temperature. The results presented herein confirm the suitability of neutron diffraction to investigate the synthesis of batches of several grams of electrode materials with well-controlled stoichiometry. Furthermore, monitoring the structural evolution of the mixtures with varying Ni:Mn content in real time reveals a delayed onset of li-thia-tion as the Mn content is increased, necessitating the use of higher annealing temperatures to achieve layering.
实时研究化学反应能够为中间体的演化提供无与伦比的见解，并可为优化反应条件提供指导。对于固态合成反应，粉末衍射已被证明是解析加热时发生的结构演化的有效工具。大规模（克到千克）合成层状富镍过渡金属氧化物具有高度相关性，因为这些材料通常用作锂离子电池的阴极。在这项工作中，利用中子衍射监测了由工业相关的氢氧化物前驱体制备的富镍阴极材料在高温合成过程中的反应机理，其中镍与锰的比例不同。进一步利用Rietveld精修对合成过程中观察到的相演化进行建模，并比较材料随温度变化的行为。本文给出的结果证实了中子衍射适用于研究几克具有精确控制化学计量比的电极材料的合成。此外，实时监测不同镍锰含量混合物的结构演化发现，随着锰含量的增加，锂化起始延迟，这就需要使用更高的退火温度来实现分层。
