  Structural identifiability analysis of fractional-order equivalent circuit
models (FO-ECMs), obtained through electrochemical impedance spectroscopy (EIS)
is still a challenging problem. No peer-reviewed analytical or numerical proof
does exist showing that whether impedance spectroscopy FO-ECMs are structurally
identifiable or not, regardless of practical issues such as measurement noises
and the selection of excitation signals. By using the coefficient mapping
technique, this paper proposes novel computationally-efficient algebraic
equations for the numerical structural identifiability analysis of a widely
used FO-ECM with Gr\"{u}nwald-Letnikov fractional derivative approximation and
two constant phase elements (CPEs) including the Warburg term. The proposed
numerical structural identifiability analysis method is applied to an example
from batteries, and the results are discussed. Matlab codes are available on
github.
