Single-Point Impedance Diagnostic for Internal Temperature Monitoring of Commercial Lithium-Ion Batteries

Temperature monitoring of commercial lithium-ion batteries is critical for maintaining safety.  Extreme temperatures can result in harmful reactions, such as SEI and/or electrode decomposition, potentially leading to catastrophic thermal runaway and total battery failure [1-3].  Measuring battery temperature is typically done on the cell surface; however, this can be inaccurate, particularly during rapid heating events where differences between surface and internal temperatures can be as high as 40-50°C [4,5].  Therefore, developing methods for accurately and rapidly determining the internal temperature of lithium-ion batteries is crucial for safe operation and possible mitigation of failure events.

One technique that has been used to instantaneously monitor the state of health and internal temperature of lithium-ion batteries is Electrochemical Impedance Spectroscopy (EIS) [6-8].  Although this method is extremely effective, one key limitation is that the maximum detectable temperature has only been shown to be around 60-65°C.  Considering that decomposition reactions typically begin around 100°C or higher, it is clear the temperature window for EIS internal temperature diagnostics will need to be expanded.

In this work, a single-point EIS diagnostic was developed using a correlation between the imaginary impedance and internal temperature of a commercial 18650 lithium-ion battery, as shown in Figure 1.  This correlation was tested via several temperature vs. time programs, and Figure 2 shows results demonstrating close agreement of fit and actual temperatures up to around 95°C.

Figure Captions:

Figure 1. EIS correlation with internal temperature, along with fit, for commercial 18650 lithium-ion battery.

Figure 2. Fit vs. actual temperatures using single-point EIS diagnostic for temperature vs. time experiment on commercial 18650 lithium-ion battery.

References:

1. N. S. Spinner, C. R. Field, M. H. Hammond, B. A. Williams, K. M. Myers, A. L. Lubrano, S. L. Rose-Pehrsson and S. G. Tuttle, J. Power Sources, 279, 713 (2015).
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5. R. A. Leising, M. J. Palazzo, E. S. Takeuchi and K. J. Takeuchi, J. Electrochem. Soc., 148, A838 (2001).
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8. N. S. Spinner, C. T. Love, S. L. Rose-Pehrsson and S. G. Tuttle, Electrochim. Acta, Submitted.