Impact of temperature on Li-ion battery impedance and compensation strategies
Maximilian Schinagl, Markus Fasching, Patrick Höschele, Christian Ellersdorfer
Abstract
Electrochemical impedance spectroscopy (EIS) is increasingly applied for the electrochemical characterization of Li-ion batteries as it can estimate the state of health (SOH), state of charge (SOC) and internal temperature. However, EIS measurements of batteries are highly sensitive to temperature, making it challenging to interpret and compare measurements correctly. This study presents two approaches based on linear regression and the Arrhenius equation to compensate for the impact of temperatures on an EIS measurement. EIS measurements on cylindrical batteries were conducted at varying temperatures and SOCs for a frequency range from 0.01 Hz to 100 kHz to assess both methods. Measurement results at 50 % SOC were used to evaluate the applicability of both methods, showing that both can compensate the temperature influence except for the frequencies 13127 Hz–20612 Hz and the frequency 1097.3 Hz. To validate both methods, they were applied to measurements taken at 30 % SOC. Resulting in a relative error of less than 0.75 % for the real impedance and less than 4 % for the imaginary impedance. The developed methods for temperature compensation will enhance the electrochemical characterization of batteries, enabling accurate interpretation and comparison of measurements. • Deduction of temperature influence on the impedance. • Methods to compensate the influence of temperature on the impedance. • Comparison of different methods and their accuracy.