Probing Electrode-Electrolyte Interfaces in Rechargeable Alkali-Ion Batteries

可充电电池在满足我们未来的能源需求方面发挥着至关重要的作用，有助于经济脱碳和实现雄心勃勃的净零排放承诺。然而，广泛的部署需要进一步提高能量密度和降低成本。由于不想要的副作用，目前的电池寿命远远低于预期，而且我们缺乏设计解决方案以显著提高容量保持所需的基本知识。电极材料的性能在很大程度上是由发生在典型的固体电极和液体电解质之间的界面上的反应决定的。在这些界面的几个纳米范围内，电子被转移，离子被溶剂化/去溶，不希望发生的副反应继续进行。了解这些界面的结构和化学演化对于开发改进的电极材料和电解液配方以及了解这些材料稳定的电化学条件至关重要。然而，在操作过程中从这些埋藏的界面中提取信息是极其困难的，因为密集的固/液相分散在大多数界面敏感的探针(如电子、离子)上。该项目的关键目标是采用强大的界面敏感技术，以便它们能够在实际操作条件下探测埋藏的电化学界面。这将结合互补X射线光谱学和中子反射术，从化学和空间上解决在液体环境中运行的电极界面的演变。经过特别调整的窗口将被开发出来，这些窗口对这些探测器(电子、X射线和中子)是透明的，但它也密封了电化学环境并充当电极。这些新功能将被用来揭示可充电碱金属(Li、Na、K)离子电池中离子插入电极上发生的界面过程。提出的操纵道方法有望改变我们对离子和溶剂在这些电解液中偏置电极上的排列方式以及对发生的反应的影响的理解。一个特别的重点将是浓缩(&gt；5m)电解液，在这些电解液中，高盐浓度被认为可以扩大电化学操作窗口，而盐的分解预计将对副反应有更大的贡献。这个项目属于能量存储和分析科学的EPSRC研究领域，目的是开发和应用新的表征工具来揭示碱性离子电池中埋藏电极-电解液界面的化学结构。这将涉及使用钻石光源和ISIS的Muon和中子源以及其他国际设施可用的X射线和中子技术。

Rechargeable batteries have a vital role to play in meeting our future energy needs, helping to decarbonise the economy and meet ambitious net-zero emissions commitments. However widespread deployment requires further increases in energy density and reductions in cost. Current battery lifetimes fall well below expectations due to unwanted side reactions, and we lack the fundamental understanding needed to design solutions to significantly improve capacity retention. The performance of electrode materials is largely defined by reactions occurring at the interfaces between typically solid electrodes and liquid electrolytes. Within a few nanometres of these interfaces, electrons are transferred, ions are solvated/desolvated, and undesired side-reactions proceed. Understanding the structural and chemical evolution of these interfaces is critical to developing improved electrode materials and electrolyte formulations, as well as understanding the electrochemical conditions under which these are stable. However, extracting information from these buried interfaces during operation is extremely challenging, due to the dense solid/liquid phases which scatter most interface-sensitive probes (e.g. electrons, ions).The key aim of this project is to adapt powerful interface-sensitive techniques, so that they can probe buried electrochemical interfaces under realistic operating conditions. This will combine complementary X-ray spectroscopy, and neutron reflectometry to chemically and spatially resolve the evolution of electrode interfaces operating in liquid environments. Specially adapted windows will be developed that are transparent to these probes (electrons, X-rays and neutrons) but which also seal the electrochemical environment and act as the electrodes.These new capabilities will then be used to reveal the interfacial processes occurring at ion insertion electrodes in rechargeable alkali metal (Li, Na, K) ion batteries. The proposed operando approach promises to transform our understanding of how ions and solvent arrange at biased electrodes in these electrolytes, and the effect on the reactions occurring. A particular focus will be on concentrated (>5M) electrolytes where high salt concentrations are thought to expand the electrochemical operating window, and salt decomposition is expected to have a more significant contribution to side reactions. This understanding will inform the selection of electrode materials and electrolyte formulations that offer improved safety and/or lower cost.This project falls within the EPSRC research areas of Energy Storage and Analytical Science, where the aim is to develop and apply novel characterisation tools to reveal the chemical structure of buried electrode-electrolyte interfaces in alkali-ion batteries. This will involve the use of X-rays and Neutron techniques available at Diamond light source and the ISIS muon and neutron source, as well as other international facilities.