Li-ion batteries are the primary energy source in many applications. However, the potential for fire and explosion due to  
mechanical damage remains a safety concern. Currently, there are no criteria about the extent of the mechanical damage under which the batteries are safe to use. Here, we investigate the effects of bending damage to Li-ion cells on their impedance spectra. After the initial characterization of four Li-ion pouch cells, one of the cells underwent a three-point bending load. We collected electrochemical impedance spectroscopy (EIS) measurements after each increment of loading. The cells in the control group went through parallel EIS measurements at the same intervals as the damaged cell. We modeled the cells using distributed equivalent circuit models and analyzed the model parameters. We observed  
that several model parameters such as the magnitude of constant phase elements had similar trends in the control cells and  
the bent cell. However, some parameters such as resistances in parallel with constant phase elements and the inductor showed dependency on the extent of the damage. These results suggest the potential for use of such parameters as an indicator of mechanical damage when visual inspection of cells is not possible in a battery pack set-up. Future steps include investigation of similar trends for other commercial batteries, chemistries, and form factors to verify the applicability of the current findings in a broader context.


Bending Detection of Li-Ion Pouch Cells Using Impedance Spectra

Division / Sponsors: 
Dynamic Systems & Control (DSCD)

Paper Proceedings: https://asmedigitalcollection.asme.org/DSCC/DSCC2020/volume/84270

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