Cathode-solid electrolyte interface in solid-state batteries

传统的锂离子电池化学正在接近其物理化学极限。需要应用高能活性材料来开发高能量密度、低成本、安全的电池，以满足不断扩大的电动汽车市场的要求，并为电动飞行等新应用提供动力。这可以通过用固体电解液取代有机液体电解液来实现，并且能够在全固态电池(SSB)配置中安全地实施锂金属阳极。SSB中的一个主要挑战是设计具有足够柔顺性的阴极，以便在活性粒子膨胀或收缩时避免高应力，以便在充放电时保持接触。商用阴极的氧化性很强，因此通常会在界面上降解固体电解质，特别是硫化物基固体电解质。人们已经研究了陶瓷涂层来抑制反应性，但机械问题仍然存在。聚合物作为阴极粒子涂层，具有机械性能、附着力、离子导电性和低界面阻抗的必要组合，有助于在循环时保持固体电解质与阴极粒子之间的接触，同时将其对倍率能力的影响降至最低。在本项目中，将研究阴极/固体电解质界面作为电荷状态、循环、电流密度、温度和压力的函数。学生将接受有关电化学表征(三电极电池)和阻抗光谱学、等离子体FIB扫描电子显微镜的形态研究、样品稀释和透射电子显微镜、操纵面X射线断层扫描和XPS的培训。将等静压与电化学相结合，建立复合材料的力学响应。该项目属于EPSRC能源研究领域。这一主题的目的是让英国实现其环境和能源目标。

The conventional Li-ion battery chemistry is approaching its physicochemical limit. High energy active materials need to be implemented to develop the high energy density, low-cost and safe batteries that can meet the requirements of the expanding electric vehicle market and empower novel applications such as electric flight. This could be achieved by replacing the organic liquid electrolyte with a solid electrolyte and enabling the safe implementation of Li-metal anodes in an all-solid-state battery (SSBs) configuration. A major challenge in SSBs is to design cathodes with sufficient compliance so that high stresses are avoided when active particles swell or contract, in order to maintain contact upon charge and discharge. Commercial cathodes are strongly oxidising, and thus generally degrade solid electrolytes at interfaces, especially sulphide-based solid electrolytes. Ceramic coatings have been investigated to suppress reactivity, but the mechanical problems remain. A polymer, as a cathode particle coating, with the necessary combination of mechanical properties, adhesion, ionic conductivity and low interfacial impedance, could help maintain contact between the solid electrolyte and the cathode particles upon cycling while minimising its impact on rate capability.In this project, the cathode/solid electrolyte interface will be studied as a function of charge state, cycling, current density, temperature, and pressure. The student will be trained on electrochemical characterisation (3-electrodes cells) and impedance spectroscopy, morphology studies by plasma-FIB SEM, sample thinning and TEM, operando X-ray tomography and XPS. Isostatic pressing will be combined with electrochemistry to establish the mechanical responses of composites. This project falls within the EPSRC Energy research area. The aim of this theme is for the UK to meet its environmental and energy targets.