Spatially resolved simulation models are valuable tools to predict the behaviour (electrical, thermal, ageing) of energy storage systems. However, parameterisation of the electrical impedance-based model is often difficult because local measurements are hardly possible. For homogeneous conditions, e.g. homogeneous current, state of charge and temperature distribution, the measured overall impedance of a cell or electrode can be divided equally over the volume elements of the spatially resolved model. Homogeneous conditions are though very rare, so all larger devices show at least a current distribution because of non-zero ohmic resistances in current collectors, active masses and electrolyte. In this paper, a method is presented and validated for calculating the local impedance of nonlinear inhomogeneous devices from the overall impedance of the device. The method consists of iteration between impedance parameter identification and calculation of current distribution.