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、帮助经济脱碳和实现雄心勃勃的净零排放承诺方面发挥着至关重要的作用。然而，广泛部署需要进一步增加能量密度和降低成本。由于不必要的副反应，目前的电池寿命远低于预期，我们缺乏设计解决方案以显着提高容量保持率所需的基本理解。电极材料的性能在很大程度上由在典型的固体电极和液体电解质之间的界面处发生的反应限定。在这些界面的几纳米内，电子被转移，离子被溶剂化/去溶剂化，并且进行不期望的副反应。了解这些界面的结构和化学演变对于开发改进的电极材料和电解质配方以及了解这些稳定的电化学条件至关重要。然而，在操作过程中从这些埋置界面中提取信息是非常具有挑战性的，因为密集的固/液相会散射大多数界面敏感探针（例如电子、离子）。本项目的主要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置的电化学界面。这将结合联合收割机互补的X射线光谱学，和中子反射测量，以化学和空间解析在液体环境中操作的电极界面的演变。我们将开发出特殊的窗口，这些窗口对这些探针（电子、X射线和中子）是透明的，但同时也密封了电化学环境并充当电极。这些新功能将用于揭示可充电碱金属（Li、Na、K）离子电池中离子插入电极处发生的界面过程。所提出的操作方法有望改变我们对离子和溶剂如何在这些电解质中的偏置电极上排列以及对反应发生的影响的理解。特别关注的是浓缩（> 5 M）电解质，其中高盐浓度被认为会扩大电化学操作窗口，并且预计盐分解对副反应有更显著的贡献。该项目福尔斯属于EPSRC能源存储和分析科学研究领域，其目的是开发和应用新型表征工具，以揭示碱离子电池中埋置电极-电解质界面的化学结构。这将涉及使用钻石光源和ISIS μ子和中子源以及其他国际设施提供的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.