Mesnier Alex, Manthiram Arumugam
Materials Science and Engineering Program and Texas Materials Institute, The University of Texas at Austin, Austin, Texas 78712, United States.
ACS Appl Mater Interfaces. 2023 Mar 15;15(10):12895-12907. doi: 10.1021/acsami.2c16326. Epub 2023 Mar 1.
In pursuit of Li-ion batteries with higher energy density, ultrahigh-nickel layered oxides are a leading candidate for next-generation cathode materials. Single-crystalline morphology offers a neat solution to the poor stability of ultrahigh-Ni cathodes; a lower active surface area mitigates electrolyte decomposition at high voltages, and the elimination of grain boundaries improves mechanical resilience and increases volumetric energy density. However, single-crystal cathodes possess their own challenges, several of which originate from synthesis at elevated temperatures meant to induce grain growth. Molten-salt synthesis is an alternative method for obtaining single crystals, accelerating grain growth through the presence of a molten flux without the need for increased temperature. Herein, we offer heuristic guidelines for molten-salt synthesis, discussing key factors for designing reaction mixtures and the necessary exploratory research for novel molten salt/cathode systems. The influence of different salts and synthesis conditions on the morphology and properties of single-crystal LiNiO is presented. It is found that oxidative salts, such as LiO and LiNO, are crucial to supplementing dissolution of gaseous oxygen into the molten phase. Through these discussions, this work aims to provide a set of overarching principles for obtaining higher-quality single-crystal layered oxide cathodes and engender more rigorous and impactful investigation into their fundamental nature and applications.
为了追求具有更高能量密度的锂离子电池，超高镍层状氧化物是下一代阴极材料的主要候选者。单晶形态为超高镍阴极稳定性差的问题提供了一个简洁的解决方案；较低的活性表面积减轻了高电压下电解质的分解，晶界的消除提高了机械弹性并增加了体积能量密度。然而，单晶阴极也有自身的挑战，其中一些源于在高温下合成以诱导晶粒生长。熔盐合成是获得单晶的另一种方法，通过熔剂的存在加速晶粒生长，而无需提高温度。在此，我们提供了熔盐合成的启发式指导方针，讨论了设计反应混合物的关键因素以及对新型熔盐/阴极系统进行必要的探索性研究。介绍了不同盐类和合成条件对单晶LiNiO形态和性能的影响。发现氧化盐，如LiO和LiNO，对于补充气态氧在熔融相中的溶解至关重要。通过这些讨论，这项工作旨在为获得更高质量的单晶层状氧化物阴极提供一套总体原则，并对其基本性质和应用进行更严格、更有影响力的研究。
