FURI | Summer 2025

Time- and Temperature-Dependent Evolution of Electrochemical Impedance Spectroscopy (EIS) in Next-Generation Batteries

Lithium- and sodium-ion batteries are essential for renewable energy, yet suffer from poor performance in cold environments, making it crucial to understand their behavior. Electrochemical Impedance Spectroscopy (EIS) applies alternating voltages over a range of frequencies to measure impedance contributions such as bulk material resistance, charge transfer resistance, and ion diffusion. These processes operate on specific timescales, so they only respond at specific frequencies. Using experimental data from EIS coupled with equivalent circuit models, the data can be modeled quantitatively. This research investigates how impedance and, in turn, ionic conductivity evolve with varying chemistry, temperature, and state of health.