Mapping Chemical, Ionic and Electronic Properties of High Capacity Cathode Materials

开发能量密度更高、成本更低的锂离子电池(LIB)是全球交通部门采用电动汽车和减少碳排放的关键要求。目前的技术在很大程度上受到阴极活性材料的限制，这意味着这里的改进将对性能产生重大好处。富镍正极材料承诺更高的容量，同时由于其较低的钴含量而降低成本。然而，这些材料存在容量加速衰减的问题，这限制了电池寿命，从而限制了它们的商业可行性。要克服这一挑战并开发改进的材料，需要了解这种容量衰减的起源，包括这些材料在反复充电和放电时结构和化学如何变化。该项目旨在应用多模式成像能力来揭示高容量阴极材料的局部化学和结构属性以及它们的电子和离子导电性之间的相互作用。解决这一问题的关键将是在空间上解决单个阴极粒子在不同循环阶段和不同循环次数后这些性质的变化，从而深入了解导致这些材料容量衰减的关键退化机制。这将涉及X射线光谱显微镜和电化学扫描探针技术，这些技术可以实现从纳米到微米的空间分辨率，并检测锂含量、过渡金属氧化态以及电子和离子电导率的变化。重点将放在研究现实的电极材料上，这些材料已经被用作法拉第研究所关于电池降解的更大项目的一部分，这些材料将按照既定的方案进行电化学循环。将开发在惰性环境下对这些样品进行切片的方法，以产生从拟议的空间化学成像技术中获得最多信息所需的平坦横截面。利用这些样品开发的理解将有助于设计正极材料和循环方案，以帮助延长锂离子电池的寿命。该项目属于EPSRC能量存储和分析科学的研究领域，该领域将使用先进的光谱显微镜技术来研究电池材料中化学、电子和离子性质之间的相关性。这包括使用钻石光源和其他国际设施提供的X射线方法。法拉第资助的学生

The development of Li-ion batteries (LIBs) with increased energy density and lower cost is a key requirement for the adoption of electric vehicles and reduction in carbon emissions in the global transport sector. Current technology is largely limited by the cathode active material, meaning improvements here will have significant benefits to performance. Nickel-rich cathode materials promise higher capacities, whilst also reducing cost due to their lower cobalt content. However, these materials suffer from accelerated capacity fading, that limits battery lifetime and consequently their commercial viability. To overcome this challenge and develop improved materials requires an understanding of the origins of this capacity fade, including how the structure and chemistry of these materials change as they are repeatedly charged and discharged. This project aims to apply multimodal imaging capabilities to reveal the interplay between local chemical and structural properties of high capacity cathode materials, and their electronic and ionic conductivities. Key to this will be spatially resolving how these properties vary within individual cathode particles at different stages of cycling and after different number of cycles, providing insights into the key degradation mechanisms responsible for capacity fade in these materials. This will involve X-ray spectromicroscopy and electrochemical scanning probe techniques that can achieve spatial resolutions from nanometres up to microns and detect variations in Lithium content, transition metal oxidation state, and electronic and ionic conductivities. The focus will be on studying realistic electrode materials already used as part of a larger Faraday Institution project on battery degradation and these will be electrochemically cycled following established protocols. Methods will be developed for sectioning these samples under inert environments to produce the flat cross-sections needed to get the most information from the proposed spatio-chemical imaging techniques. The understanding developed using these samples will inform the design of cathode materials and cycling protocols to help extend the life of Li-ion batteries.This project falls within the EPSRC research areas of Energy Storage and Analytical Science, where advanced spectromicroscopy techniques will be used to study the correlation between chemical, electronic and ionic properties in battery materials. This will include the use of X-rays methods available at Diamond light source and other international facilities.Faraday funded student