High performance laboratory X-ray absorption spectroscopy system

我们在这项建议中的目标是更好地了解功能聚合物材料和二次资源中非晶态结构的化学。聚合物电解质膜是许多电化学单元的重要组成部分，如钒氧化还原液流电池(VRFB)。它们既是独特的离子导体，又是离子屏障。在VRFB中，PEM是理想的质子传输器，并且对钒离子是不渗透的。钒离子的交叉是VRFB容量衰减的主要原因。虽然这一现象已经得到了很好的研究，特别是在Nafion上，但离子在质子交换膜中的输运还不清楚。由磺酰基和水的亲水作用形成的介观水合通道的内部化学与自由水有很大的不同。我们的具体目标是确定有助于钒离子在膜中传输的化学反应和相互作用，例如与磺酰基团的相互作用和钒氧化还原对的反应。我们研究Nafion和新型的质子交换膜，它们价格较低，可以设计成具有不同特性的，例如交联剂的梯度。实验室的X射线吸收光谱仪系统(L-XAFS)将使我们能够直接测定水合膜中钒离子的氧化状态和化学环境，这是很难研究的。我们在项目过程中获得的理解将使我们和其他人能够开发更具选择性的膜。此外，我们将致力于更好地了解回收炉渣中无定形化合物和结晶化合物的形成。长期目标是能够以一种经济的方式从回收炉渣中回收关键元素。这可以通过在工程人造矿物(EAMS)中富含关键元素来合成非晶态和晶态化合物来实现。人们对炉渣中无定形成分的形成和结构知之甚少。我们的初步研究表明，氧化还原活性元素如锰具有直接影响。虽然X射线衍射可以跟踪晶体结构的形成，但很难研究非晶态结构的形成。我们的具体目的是更好地了解锰，特别是它的价态对锂离子电池回收废渣中非晶态结构形成和EAMS的影响。L X射线荧光光谱分析使我们能够研究非晶态结构的一致性，并在适当的实验参数下研究它们的形成。我们期望对这一进程有一个基本的了解，这也将适用于其他系统。到目前为止，XAFS几乎只在Synchrotron Sources上提供。X射线光学和X射线管的新发展使现在能够在实验室中使用该系统进行大多数必要的分析，而该系统受这一提议的制约。

Our objective in this proposal is to better understand the chemistry of amorphous structures in functional polymer materials and secondary resources. Polymer electrolyte membranes (PEMs), are an important part of many electrochemical units like Vanadium redox flow batteries (VRFB). They serve as unique ion conductors and ion barriers simultaneously. In VRFBs the PEM is ideally transporting protons and is impermeable for Vanadium ions. The cross over of Vanadium ions is a main reason for capacity fade in VRFBs. Though this phenomenon is well studied especially on Nafion, the transport of ions in the PEM is not yet understood. The chemistry inside of the mesoscopic, hydrated channels inside the membrane, which are formed by hydrophilic interactions of the sulfonyl-groups and water, is quite different from that of free water. Our specific aim is to identify chemical reactions and interactions which are contributing to Vanadium ion transport in the membrane e.g. interaction with the sulfonyl groups and reactions of Vanadium redox pairs. We study Nafion and novel PEMs which are less expensive and can be designed with variable characteristics e.g. gradient of cross linkers. The laboratory X-ray absorption spectrometer system (L-XAFS) will allow us to determine the oxidation state and the chemical surrounding of Vanadium ions directly in the hydrated membrane which is difficult to study other vice. The understanding we will have gained in the course of the project will enable us and others to develop more selective membranes. Additionally, we will work on a better understanding of the formation of amorphous and crystalline compounds in recycling slags. The longterm goal is to enable an economic way to retrieve critical elements from recycling slags. This can be achieved by synthesizing amorphous and crystalline compounds with the critical elements being enriched in engineered artificial minerals (EAMs). Only little is known on the formation and structure of amorphous components in slags. Our preliminary studies show that redox active elements like Manganese have a directive influence. While the formation of crystalline structures can be followed by X-ray diffraction, it is difficult to study the formation of amorphous structures. Our specific aim is to better understand the influence of Manganese and especially its valence on the formation of amorphous structures and EAMs in slags stemming from the recycling of Li-ion batteries. The L-XAFS allows us to investigate the identity of amorphous structure and with the appropriate experimental parameters also to investigate their formation. we expect to gain a fundamental understanding on this process which will be applicable also to other systems. Until now XAFS is nearly exclusively available at Synchrotron sources. New developments in X-ray optics and X-ray tubes enables now to perform a fast majority of the necessary analyses in the laboratory with the system which is subject to this proposal.