In-operando X-ray difffraction analysis of a pouch cell battery

As the energy transition from fossil fuel to more sustainable sources is at full speed, the need for electrochemical energy storage keeps rising. Currently, Li-ion batteries are present in any portable electronic device and in electrical vehicles. While Lithium provides a large part of the currently available electrode materials, the availability of Li on Earth remains small, and thus alternative elements such as Na or Mg are being considered to replace it.

The development of low-cost electrode materials using alternative elements has been a topic of high interest in the scientific community for years now. Researchers are touching on various fields including electrode material characterization, investigation of the local structure and, in situ and in operando experiments.

Phase changes during charge-discharge cycle

Among the causes of battery degradation is the loss of reversibility of the Li-ion migration process. This process can happen via insertion, alloying, or phase change, and, the latter in particular, typically cause volume expansion/contraction. This sudden volume variation may trigger particle cracking. In its turn, the cracking results in loss of battery performance. X-ray diffraction (XRD) can detect the phase changes and their reversibility with great precision.

In situ v/s ex situ and in operando

Specifically, in situ and in operando XRD measurements of a complete battery, can help you track the changes in the lattice parameter or in the crystal phase itself.

In situ XRD analysis allows the structural analysis of electrode materials within the electrochemical cell at specific states of charge, as opposed to the more conventional ex-situ analysis which requires the disassembling of the cell and the extraction of the electrodes for the XRD analysis.

The operando (Latin word for “operating”) technique, allows the characterization of the structural evolution of the crystalline phases contained in batteries and pouch cells, simultaneous with the operation of the reaction, under non-equilibrium and real-time conditions[1,2].

In situ and in operando battery analysis

The combination of in situ with in operando XRD is a very powerful tool that the research community uses quite often. In the home lab, you can use the techniques either in reflection geometry or in transmission geometry. However, in order to perform the measurements in transmission geometry, you typically require more penetrating radiation. For instance Mo or Ag X-ray anodes.

Look deep inside the battery processes

If you are interested in learning more about the specific experimental setup, then join our next Ask an Expert! webinar. We will cover the most important experimental aspects for the in situ and in operando XRD measurements of complete battery cells and answer your questions.

Previously in the ‘Ask an Expert! blog series:

References

[1] I. Buchberger et al., Journal of The Electrochemical Society 162(14), A2737-A2746 (2015)
[2] N. Sharma et al., ChemSusChem , 8, 2826-2853 (2015)