A new approach to modeling and simulation of the nonlinear, fractional behavior of Li-ion battery cells

Two nonlinear infinite dimensional models of a Lithium-ion battery are introduced. The proposed models interpolate linear fractional models which are obtained from a widely spread equivalent circuit model. The linear models are parameterized by means of so-called dynamic impedance measurements, i.e. impedance measurements in several operating points. In each operating point, the fractional input output behavior is recovered by an infinite dimensional state space description. For numerical implementation the introduced models require for an appropriate approximation. Therefore, a Krylov subspace method and a finite element approach are proposed. The nonlinear lumped parameter models are validated on the basis of experimental data.