Investigation and comparison of the electrochemical impedance spectroscopy and internal resistance indicators for early-stage internal short circuit detection through battery aging

Abstract

It is crucial to identify the battery's internal short circuit (ISC) for safety. The study aims to explore the effectiveness of ISC detection methods through battery aging. Two types of method are compared in this work: diffusion coefficient calculation based on electrochemical impedance spectroscopy and conventional internal resistance monitoring through algorithms such as recursive least square (RLS). In this work, the frequency-domain P2D model is built to simulate the behavior of the impedance response with different levels of ISC. Then, coin cells are assembled with conductive contaminants to examine the accuracy of the model simulation and the actual influences of the ISC on the impedance. Afterwards, with the proven impedance model and potential influences, the substituted ISC test on commercial 18,650 cells is applied to examine ISC detection based on EIS under different aging statuses. Finally, the conventional internal resistance identification method is used for comparison. The coin cell experimental results in the study indicate that the inception of the ISC mainly alters the low-frequency impedance with much reduced phases, which is also predicted by the model simulation. Similar results with the impacted low-frequency impedance can also be observed in the substituted ISC test for the commercial cells. The diffusion coefficients, the parameter mainly associated with the low-frequency impedance response, increased by 47–143 % as the battery SOH decreased from 100 % to 87 %. In comparison, the internal resistance identification method indicates that the ohmic component is relatively stable after the inception of the ISC. The polarization component of the internal resistance exhibits a significant change as high as 234 %. However, as the battery's SOH decreases, the effectiveness of the polarization resistance fades toward 23 %.