Intregrating Modeling and Experimental Results for Li-Ion Batteries at Cold Temperatures for Experimental Applications

The performance of lithium-ion (Li-ion) batteries weakens at low temperatures due to lower electrolyte conductivity and slower reaction rates. This is a critical issue in space exploration, where temperatures can drop to -80°C. While batteries have been tested across various temperature ranges, the physical mechanisms affecting battery performance across these extremes remains underexplored. Additionally, rest periods in discharge cycles, also affect long-term battery performance, especially in cold environments where Joule heating is interrupted.



In this study, two computational models are developed: a simplified equivalent circuit model based on experimentally derived components and a more detailed physical model incorporating factors like diffusivity, conductivity, and reaction kinetics. Both models are temperature-dependent and designed to assess battery behavior over multiple cycles, considering operating currents, cell geometries, and rest periods between charge and discharge. The two models are then compared to experimental data on coil cell-based Li-ion batteries, evaluated at colder temperatures using different refrigerator settings in the lab.



Initial results demonstrate similarities in the voltage and temperature profiles between the two models, but some limitations are noted in the capabilities of the circuit model. Electrochemical Impedance Spectroscopy (EIS) tests can help determine the dependence of the different circuit components (i.e. resistance, capacitance) to better fit the circuit model and enable alternative circuit configurations to be constructed. EIS tests at different temperatures can be compared to both models. Finally, long-term cycling experiments will be conducted at different temperatures and cycling loads, and determine the effect of aging on the battery’s performance, which can be incorporated into the model as a decay as well. Understanding the long-term cycling capabilities of the battery can help better understand limitations to the battery’s performance and motivate alternative battery chemistries which can survive at lower temperatures for larger numbers of cycles.