Multiscale tomographic analysis of the thermal failure of Na-Ion batteries

Robinson, J. B., Heenan, T. M. M., Jervis, J. R., Tan, C., Kendrick, E., Brett, D. J. L., & Shearing, P. R. - Electrochemical Innovation Lab, Department of Chemical Engineering, UCL, London, Warwick Manufacturing Group, University Road, University of Warwick, Coventry,School of Chemistry, University of Birmingham, Edgbaston, Birmingham

In recent years, the ability to examine the processes that cause the catastrophic failure of batteries as a result of thermal runaway has improved substantially. In this work, the effect of thermal runaway on the microstructure of the electrodes of a Na-ion battery is examined using X-ray computed tomography for the first time. The thermal failure induced via accelerating rate calorimetry enabled the examination of failed electrodes, which were subsequently compared with fresh samples. Pre- and post-mortem microstructural analysis shows changes in both electrodes as a result of the thermal runaway process at the micrometre length-scale. It is seen that the cathode shows the largest changes in structure, with the anode remaining morphologically similar post-failure at the sub-micron length-scale. The formation of a highly X-ray attenuating layer, which is proposed to be a metallic product of the thermal runaway reaction, is observed, indicating that the thermal runaway mechanisms which occur in Na-ion batteries may be similar to those reported for Li-ion systems.

How Amira-Avizo Software is used

Visualisation was achieved in Avizo software. Segmentation of the data was performed using a greyscale threshold technique which identified distinct phases in the sample based upon variations in the histogram collected during the tomographic scans.