Fractional algebraic identification of the distribution of relaxation times of battery cells

In this paper, an algebraic model-based approach for the identification of a battery's distribution of relaxation times (DRT) is illustrated. The DRT is directly linked to physically interpretable parameters to determine the aging of a battery cell. The approach derives from Mikusiński's operational calculus. Therefore a novel integration operator and the differentiation rule for fractional systems is presented. The identification is exact in that no approximations of the novel operator are used. The procedure is verified by simulation results.