Operando XRD in the Home Lab
Dennis Becker
Bruker AXS, Karlsruhe
Energy materials are an important current field of research and powder diffraction is a key tool in understanding the materials involved, before assembly, during use and for so-called postmortem analysis. Specifically analyzing a battery during use in an operando setting, requires a high photon flux, powerful detector, special sample holders and coordination of XRD and electrochemical measurements. Due to these requirements this type of experiment is usually restricted to dedicated research instruments, requiring not only a high investment but also self-made parts and demanding software handling for data acquisition and especially data evaluation.
To make these experiments more accessible, we want to demonstrate the capability of typical lab diffractometers to perform operando experiments out of the box by using only few accessories and a full software integration of a potentiostat.
A single layered pouch cell battery has been charged and discharged while XRD patterns have been recorded continuously with different instrument setups. The acquired data sets have been evaluated by Rietveld refinement with DIFFRAC.TOPAS V7. The layered nature of the sample has been modelled appropriately using the macros published by Rowles and Buckley [1]. The results emphasize that even XRD instruments which are not purely dedicated to operando XRD can deliver high quality patterns which allow to extract lattice parameters and relative phase portions of the anode and cathode materials during cycling.
[1] Rowles, M. R. & Buckley, C. E. (2017). J. Appl. Cryst., 50, 240-25.