Interfacial characterization of hybrid solid-liquid electrolytes for Li-metal anode batteries

为了满足未来便携式电子产品和电动汽车对体积和重量能量密度的要求，需要成功地实施金属锂。SOLBAT计划在理解Li-金属|Se界面枝晶形成和扩展的原因方面取得了良好的进展。在阴极，活性粒子在充放电过程中的体积变化使SE内的亲密接触保持不变是一个重大问题。目前，已确定的SE候选材料中没有一种具备解决这一问题所需的电化学稳定性、离子导电性和机械性能的组合。固体-液体混合电解液(HSE)电池将固体保护的阳极与传统的充满液体的多孔阴极相结合，将是实现金属阳极电池实际应用的一条更容易实现的途径。在这个项目中，学生将研究固体电解质-液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，使用一系列技术，包括电化学阻抗谱(3个和4个电极)、拉曼、原子力显微镜、X射线光电子能谱、FIB/等离子-扫描电子显微镜的形貌研究、样品变薄、TEM-EDX和接触角测量。我们将优先考虑与锂金属接触的具有稳定性的固体电解质，即石榴石LLZO，并探索掺杂、颗粒尺寸和表面粗糙度/形貌对界面阻抗的影响。利用X射线衍射仪、带EDX的扫描电子显微镜和EBSD、XPS、AFM和扫描电子显微镜辅助的纳米压痕等表征方法来表征电镀锂在电池条件下的微结构，并将其与由此产生的循环/失效行为联系起来，特别是机械性能。建立对微观结构随电化学条件的变化以及由此导致的性能变化的理解。EPSRC研究领域主题：能源

A successful implementation of lithium metal is required to meet the volumetric and gravimetric energy density requirements of portable electronics and electric vehicles of the future. The SOLBAT project has made a good progress in understanding the causes of dendrite formation and propagation at the Li-metal|SE interface. At the cathode, volume changes of active particles during charge/discharge make retention of intimate contact within the SE a significant problem. Currently, none of the identified SE candidates have the necessary combination of electrochemical stability, ionic conductivity and mechanical properties to address this issue. A hybrid solid-liquid electrolyte (HSE) cell in which a solid-protected anode is combined with a conventional liquid-filled porous cathode would represent a more readily implementable route to the practical implementation of metal anode batteries. A HE, introduces a new solid/liquid interface, poorly investigated in the literature but often associated with high impedances.In this project, the student will investigate the solid electrolyte-liquid electrolyte interface as a function of charge state, cycling, current density, temperature and pressure, using a range of techniques including electrochemical impedance spectroscopy (3 and 4 electrodes), Raman, AFM, XPS, morphology studies by FIB/plasma-SEM, sample thinning and TEM-EDX and contact angle measurements. We will prioritize solid-electrolytes with proven stability in contact with Li-metal, i.e. Garnet LLZO and explore the effect of doping, grain size and surface roughness/morphology on the interfacial impedance. Strategies to mitigate high impedances, e.g. surface treatments and coatings will be investigated.Utilise characterisation methods including XRD, SEM with EDX and EBSD, XPS, AFM and SEM assisted nanoindentation to characterise the microstructure of electroplated lithium in cell conditions and tie this to the resultant cycling/failure behaviour, with particular focus on the mechanical properties. Establish an understanding of the changes in microstructure with changing electrochemical conditions, and the resultant changes in performance.EPSRC research area Theme: Energy