All-solid-state battery technology are one of the promising competitors of current liquid electrolyte-based lithium ion batteries due to high energy density characteristic. However, due to low ionic conductivity of solid materials, all-solid-state batteries become hot topic for research. In this paper we have developed a methodology based on block-oriented nonlinear system that is able to detect, quantize and model the battery voltage distortion. Two solid-state coin cell with different ionic conductivity at cathode interface are manufactured and excited with multisine signal. The Best Linear Approximation (BLA) method has been used to separate linear frequency response function (FRF) from nonlinear distortion which have been modeled with structural nonlinear modeling technique.