The battery resistance and aging processes are a function of the temperature, state of charge (SoC), and current profiles a battery experiences over its lifetime. Consequently, it seems intuitive that the same dependencies apply to the extracted parameters of an equivalent circuit model. Therefore, this study aims to deepen the understanding of the factors influencing the extracted parameters by performing pulse tests under different experimental conditions. Here, the effects of different temperatures (10°C, 20°C, 30°C, 45°C) on the extracted parameters of an n-RC model are investigated.
Furthermore, an alternative approach to separate different electrochemical processes within the battery is presented. The newly introduced distribution of resistances and times constants (DRTC) presents an alternative approach with a more intuitive, less ambiguous, and easily interpretable representation compared to a conventional distribution of relaxation times (DRT). Instead of applying tedious and ambiguous regularization methods and transferring frequency data into time domain, one simply uses the extracted parameters from pulse tests in time domain.
The presented results have been verified for four battery types: one cylindrical-, two pouch-cells with NMC/graphite chemistry, and one cylindrical-cell with NMC/graphite-silicon doped chemistry.