Project Details
Projekt
High performance laboratory X-ray absorption spectroscopy system
Subject Area
Analytical Chemistry
Term
Funded in 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 426693405
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.
DFG Programme
Major Research Instrumentation
Major Instrumentation
Hochleistungslaborröntgenabsorptionsspektrometer
Instrumentation Group
4030 Röntgenfluoreszenz-Spektrometer
Applicant Institution
Technische Universität Clausthal
