(Invited) Coupling a Versatile Reference Electrode and Porous Electrode Modeling for Battery Performance Diagnostics

A thin, porous, separator-supported reference electrode disposed between an anode and cathode is utilized as a practical, implementable solution for measuring individual electrode potentials in a commercial lithium-ion cell. Its precise placement at the midpoint of the cell stack and permeable layer design allow for the determination of the anode and cathode potential, while affecting the electrochemical performance of the cell only to the extent of adding one extra separator. In this work, we detail the various diagnostics enabled by the versatile reference electrode, both through experimental measurements, electrochemical models calibrated via the reference electrode, and in-vehicle reference electrode options. From an experimental diagnostic perspective, the versatile reference electrode has enabled the detection and avoidance of lithium plating in lithium ion batteries 1 , deconvoluted the resistance increase in batteries subject to varying thermal gradients 2 , and provided an experimental diagnostic of the charge capability under vehicle equivalent fast charge protocols 3 . A variety of electrochemical, electrochemical-mechanical, and electrochemical-thermal models have also been calibrated using a versatile reference electrode, which has enabled estimation of downstream battery performance diagnostics and impacts. These include models utilized to perform an estimation of the lithium salt transport in pouch cells 4 , predict volume change in porous electrodes 5–7 , and estimate the heat generation 8,9 in lithium ion batteries considering reversible and irreversible heat generation. Finally, various in vehicle and in-situ battery cell implementations 10–12 will be reviewed considering a controls, state estimation, and diagnostics perspective. References U. Janakiraman, T. R. Garrick, and M. E. Fortier, J. Electrochem. Soc. , 167 , 160552 (2020). X. Du et al., Journal of Power Sources , 587 , 233688 (2023). B. J. Koch, J. Gao, A. Zhang, R. Taha, and T. R. Garrick, "A Versatile Reference Electrode for Lithium Ion Battery Use", Journal of The Electrochemical Society , (Under Review) . T. R. Garrick, J. Gao, X. Yang, and B. J. Koch, J. Electrochem. Soc. , 168 , 010530 (2021). T. R. Garrick et al., J. Electrochem. Soc. , 170 , 060548 (2023). T. R. Garrick et al., J. Electrochem. Soc. , 171 , 073507 (2024). T. R. Garrick et al., Journal of The Electrochemical Society , 171 , 103509 (2024). T. R. Garrick et al., J. Electrochem. Soc. , 171 , 023502 (2024). A. Paul et al., ECS Adv. , 3 , 042501 (2024). D. R. Baker, M. Verbrugge, and B. J. Koch, J. Electrochem. Soc. (2024) http://iopscience.iop.org/article/10.1149/1945-7111/ad6379. J. Gao, B. J. Koch, and T. R. Garrick, (2023) US Patent App US20230091154A1. H. Zhang, T. R. Garrick, and B. J. Koch, (2024) US Patent App US20240072565 Brian J. Koch et al 2024 J. Electrochem. Soc. 171 123505 T. R. Garrick, B. J. Koch, J. Gao, A. Zhang, and J. S. Lowe, "Modeling Losses in a Three Electrode System Towards Fast Charge Control", J. Electrochem. Soc. , (Under Review) Figure 1