**3. Conclusions**

As research into novel cell chemistries has expanded over the past few decades, it is clearly of grea<sup>t</sup> scientific interest to visualize the electrodes of electrochemical cells at all stages in their developmental lifecycle to extract performance gains and maximize their capacity, power, and lifetime. Through in-situ and operando X-ray tomography, electrode microstructures can be visualized in 3D as a function of variables such as state of charge and cell age and conditions such as thermal abuse or overcharging. We believe that in-situ and operando tomography will ultimately achieve a similar impact to X-ray diffraction and spectroscopy in the design and engineering of new battery materials.

In addition to qualitative observations on electrode degradation, techniques such as digital volume correlation can be used to track and quantify microstructure evolution chronologically within the electrodes. With a better understanding of the fundamental processes occurring at the electrodes and how cell conditions and configurations affect these processes, electrode materials can be optimized to improve their lifetime and performance. The improvements in spatial and temporal resolutions gained from the use of optimized cell designs for micro-CT far outweigh the impact on electrochemical performance these designs may have.
