The distribution of relaxation times as basis for generalized time-domain models for Li-ion batteries

A novel approach for the development of a model for Li-ion batteries with the potential for application in on-board diagnostic is introduced. This approach is not tied to a particular electrochemistry, and has the advantages of scalability and automatable parameterization as well as feasibility regarding an implementation on microcontrollers. The dynamic behavior of the cell under test, a Li-ion pouch cell with a graphite anode and a blend cathode, is characterized in an extremely broad frequency range from 100 kHz to 17 μHz. The introduced model gives predictions consistent with the experimental data, its accuracy depends on the assumed number of relaxation times respectively model order. Recommendations concerning application are given and limitations of the approach are discussed. ► A new method for creating automated parameterized time-domain models is introduced. ► Impedance measurements in a broad frequency range are performed. ► The Distribution of Relaxation Times (DRT) is calculated. ► The model is successfully validated with different current profiles in the time-domain. ► The advantages and limits of this modeling approach are discussed.