Mechanical properties of solid state batteries

固态电池是一种新兴的储能技术。与传统锂离子电池相比，它们具有显著的优势，包括更高的能量密度和更高的安全性。它们已被确定为运输电气化的关键工具。然而，人们对系统材料成分的机械性能知之甚少，尤其是固态离子导体、阳极和阴极之间的界面，大多数工作都集中在系统的化学性质上，尽管它们的机械数据是工业应用中部署的关键。该项目最初将侧重于固体电解质的机械性能。这将包括用于固态钠电池的钠- β氧化铝系统和用于锂离子电池的LLZO。由于这些材料的高度反应性质及其对空气的敏感性，所有的工作都必须在惰性气氛中进行。该项目将利用牛津大学最近在新型手套箱基础上的投资，在SEM微机械测试设备。首次将核材料和航天材料中常用的方法应用于储能材料。这将使用通过聚焦离子束加工产生的样品，然后使用原位纳米压痕进行测试。这样就可以获得失效机理的基本信息。在此之后，该项目将继续研究电解质与阳极和阴极材料之间的机械性能。众所周知，这些接口在操作过程中的退化会限制电池寿命，了解它们是如何失效的是关键。这将包括观察电解质阴极和电解质阳极界面。由于这些可能是金属-陶瓷和金属-聚合物界面，它们将表现出非常不同的机械响应，了解这些界面的失效机制对电池寿命模型的发展非常重要。为了理解力学数据的物理基础，简单系统的有限元建模将与实验工作的数据种子模型一起使用。本项目将采用一系列新颖的纳米和微机械压痕方法来研究固态电池材料的硬度、弹性模量、屈服应力和断裂韧性。这些性质将通过扫描电子显微镜（SEM）、电子背散射衍射（EBSD）和拉曼光谱分析与局部微观结构特征有关。最后，将这些微观力学性能与通过四点弯曲试验获得的整体断裂性能进行比较。以这种方式产生的数据不仅对播种模型有用，而且可以优化加工路线，以提高电解质的使用寿命。这项工作符合EPSRC的能源主题。

Solid state batteries are an emerging technology in energy storage applications. They have significant advantages over traditional lithium ion batteries including higher energy density and increase safety. They have been identified as a key tool in the electrification of transport. However little is understood about the mechanical properties of the material components of the system and especially the interfaces between, solid state ionic conductors, anodes and cathodes with most work focusing on the chemistry of the systems even though them mechanical data is key to deployment in industrial applications.The project will initially focus on the mechanical properties of solid electrolytes. This will include the sodium-beta alumina system for solid state sodium batteries and LLZO for use in the lithium ion batteries. Due to the highly reactive nature of these materials and their air sensitive nature all work must be carried out in inert atmosphere. The project will leverage recent investments in Oxford in novel glove box based, in SEM micromechanical testing equipment. Taking methods usually used in nuclear and aerospace materials and applying them to energy storage materials for the first time. This will use specimens produced through focused ion beam machining then tested using in-situ nanoindentation. In this way basic information on the failure mechanism will be obtained. Following this the project will move onto look at the mechanical properties between the electrolyte and the anode and cathode materials. The degradation of these interfaces during operation is known to limit battery life, and understanding how they fail is key. This would include looking at the electrolyte cathode and electrolyte anode interface. As these are likely to be metal-ceramic and metal-polymer interfaces they will exhibit very different mechanical responses and understanding the failure mechanisms in these is important to the development of battery life models. To understand the physical basis of the mechanical data finite element modelling of simple systems will be used with the model seeded with data from the experimental work.This project will use a range of novel nano and mico-mechanical indentation methods to study, the hardness, elastic modulus, yield stress and fracture toughness of solid state battery materials processed in both bulk and thin film forms. These properties will be related to local microstructural features through the use of scanning electron microscopy (SEM), Electron back scattered diffraction (EBSD) and Raman Spectroscopy. Finally these micromechanical properties will be compared to bulk fracture properties obtained through four point bend flexure tests. The data produced in this way will not only be useful for seeding models but allow optimisation of processing routes for producing electrolytes with improved lifetime . This work fits into the EPSRC energy theme.