Investigation of Distribution of Relaxation Times (DRT) feature attribution in lead-acid battery

Distribution of Relaxation Times (DRT) is a promising technique for analyzing electrochemical impedance spectroscopy (EIS) without requiring prior knowledge. However, DRT research for lead-acid batteries (LAB) remains underdeveloped, and parameters selection in regularization - based DRT calculations, like λ, lacks scientific basis. This study employs the Non - dominated Sorting Genetic Algorithm II (NSGA - II) to optimize the DRT calculation, validated on RC and 2-RC circuit structures. The optimized method calculates LAB DRT curves under different temperatures, states of charge (SOC), and electrolyte concentrations. Subsequently, the effects of different operational states on the DRT are analyzed, and the physical meanings of DRT peaks are clarified and validated through equivalent circuit model (ECM). Results demonstrate that the proposed method can accurately and stably determine DRT calculation parameters. The LAB DRT curve exhibits 4–5 peaks. From high to low frequency, they correspond to the battery's charge - transfer resistance at the negative electrode, charge - transfer resistance at the positive electrode, and the ion diffusion resistance.