Fluoride-ion batteries

具有更高能量密度的可充电电池对于满足消费电子产品、电动汽车和蓬勃发展的可再生能源经济日益增长的需求是至关重要的。随着锂离子化学接近其热力学极限，人们正在研究新的化学物质，主要是基于锂的。氟位于元素周期表的另一端，是电负性最强的元素。因此，氟离子在电化学上非常稳定，并且具有很大的电化学稳定窗口。由于这些特性，氟离子电池(FIB)的理论体积能量密度比锂空气电池的理论值高出50%，使其成为下一代高能量密度电池的理想候选者。然而，在这个初始阶段，纤维增强锂离子电池正负极的充放电机制还不是很清楚，还没有确定能够长期稳定循环的电解液，也还没有建立起合适的参比电极。因此，氟离子电池还远远没有达到商业应用所要求的循环性能。本项目旨在研究适合用作电极材料的金属氟化物及其充放电机理。开发离子液体基电解液，以提高纤维增强塑料的整体性能。为此，本论文将利用透射电子显微镜和扫描电子显微镜对过渡金属氟化物正极材料在循环过程中的结构和形貌变化进行表征，以研究其电化学相演变和质量/电荷传输。此外，还将探索新的原位透射电子显微镜和X射线技术，以收集实际电池条件下的时间分辨结构和化学数据。为了实现电池的完美工作，还需要对电解液进行深入研究。因此，为了提高电池的稳定性和离子导电性，需要研究一种使用离子液体的最佳电解液组成。将特别注意调整电极表面成分，以减少溶解和副反应。整个项目将涉及使用表面/界面表征技术，包括阻抗谱、X射线光电子能谱(XPS)、拉曼光谱和扫描电子显微镜与能量色散X射线能谱(SEM-EDX)。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。

Rechargeable batteries with higher energy densities are fundamental to meeting the ever-increasing requirements of consumer electronics, electric vehicles, and a burgeoning renewable energy economy. With the Li-ion chemistry approaching its thermodynamic limit, new chemistries are being investigated, mostly Li-based. Fluorine, sitting at the opposite end of the periodic table from lithium , is the most electronegative element. Fluoride-ions are therefore electrochemically very stable and possess a large electrochemical stability window. Because of these characteristics, fluoride ion batteries (FIBs) have a theoretical volumetric energy density which is 50% higher than the theoretical value for lithium-air cells, making them the ideal candidate for the next generation of high energy density batteries. However, at this incipient stage, the charge/discharge mechanism at both positive and negative electrodes in FIBs is still poorly understood, a liquid electrolyte for long-term cycling stability has not been identified and a suitable reference electrode has not yet been established. As a result, fluoride ion batteries are still far from reaching the cyclability required for commercial applications.This project aims to investigate suitable metal fluorides to be used as the electrode materials and their charge/discharge mechanism. Ionic-liquid based electrolytes will be developed to improve the overall performance of FIBs. To this end, the electrochemical phase evolution and mass/charge transport of transition metal fluoride cathodes will be investigated, by characterizing the structural and morphological changes during cycling through ex-situ TEM/SEM (i.e. transmission electron microscopy and scanning electron microscopy). In addition, new in-situ TEM and X-ray techniques will be explored for the collection of time-resolved structural and chemical data under realistic battery conditions. An in depth study on the electrolyte will also be required in order to achieve a perfectly working battery. Hence, an optimum electrolyte composition using ionic liquids will be investigated in order to improve the stability and ionic conductivity of the battery. Particular attention will be focused on tailoring the electrode surface compositions to mitigate dissolution and side reactions. The overall project will involve the use of surface/interfacial characterization techniques including impedance spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman, and scanning electron microscopy with energy disperse X-ray spectroscopy (SEM-EDX).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.