Separating ion and electron transport kinetics in aqueous ion storage battery materials

该项目旨在采用新颖的时间分辨x射线光谱和结构表征技术，实时跟踪氧化态变化和（对于某些存储离子）离子传输，详细了解这些过程是如何相互关联的，以及它们对PBA基电池电极结构完整性的影响。这些信息将使我们能够更深入地了解PBA电池电极的充电、放电和退化机制。这些目标将通过完成以下工作包和目标来实现：(i)合成一系列PBA电极材料，并使用传统的XRD和拉曼分析对这些材料进行物理表征，然后将这些材料制成电池阴极，并表征其充放电容量和速率，用于在水溶液中储存Na+， Mg2+， Ca2+和Zn2+。本包的目的是对文献中已知的材料进行基准测试，并进一步了解PBA组成和结构对电极材料的存储容量和充电速率的作用。（ii）设计和测试一种电化学电池，使其能够对PBA电池电极进行操作式x射线吸收光谱（XAS）和x射线衍射（XRD）研究，目的是确保在（iii）和（iv）中进行的操作式x射线吸收光谱（XAS）和x射线衍射（XRD）测量能够代表(i)部分中使用的理想电化学电池几何形状。（iii）使用操作式电池收集时间分辨x射线吸收光谱数据。这将需要电化学控制系统（一个恒电位器）与光束线硬件和软件的接口。所获得的数据将独特地使人们能够了解PBA材料中每种金属离子的氧化态变化的相对速率。（iv）收集operando XRD数据，以补充第（iii）部分进行的时间分辨XAS，这将有助于更深入地了解离子储存和放电过程中PBA材料的任何伴随结构变化以及循环（降解）的影响。实现这一目标将需要实现XRD检测器和开发数据采集协议。

The proposed project seeks to employ novel time resolved X-ray spectroscopic and structural characterisation techniques to follow the oxidation state changes and (for some stored ions) the ion transport in real time, providing a detailed understanding of how these processes are interrelated and their effects on the structural integrity of the PBA based battery electrodes. Such information will enable a deeper understanding of the mechanisms of charging, discharge, and degradation of the PBA battery electrodes. These aims will be accomplished through completion of the following work packages and objectives:(i) Synthetic preparation of a series of PBA electrode materials and physical characterisation of these materials using conventional XRD and Raman analysis, followed fabrication of the materials into battery cathodes and characterisation of their charge/discharge capacities and rates for the storage of Na+, Mg2+, Ca2+, and Zn2+ in aqueous electrolytes. The objectives of this package are to benchmark the materials prepared against the best known in the literature and further understanding of the roles of PBA composition and structure on the storage capacities and charging rates of the electrode materials.(ii) Design and testing of an electrochemical cell to enable operando X-ray absorption spectroscopic (XAS) and X-ray diffraction (XRD) studies of the PBA battery electrodes, with the objective of ensuring that the operando XAS and XRD measurements to be conducted in (iii) and (iv) are representative of the ideal electrochemical cell geometry used in part (i).(iii) Collection of time-resolved X-ray absorption spectroscopic data using the operando cell, which will require interface of the electrochemical control system (a potentiostat) with the beamline hardware and software. The data acquired will uniquely enable understanding of the relative rates of the oxidation state changes of each of the metal ions in the PBA materials. (iv) Collection of operando XRD data to compliment the time resolved XAS conducted in part (iii), which will enable a deeper understanding of any accompanying structural changes to the PBA materials during ion storage and discharge as well as the effects of cycling (degradation). Accomplishing this objective will require implementation of an XRD detector and development of the data acquisition protocols.