Requirements for Applying the Current Interruption Technique for Reconstructing the Impedance of Li-Ion Batteries

Electrochemical impedance spectroscopy is a non-destructive technique that provides useful information on the status of a lithium-ion battery, including its state-of-health. However, conventional harmonic perturbation methods are too sophisticated for applications in operating environments. This study systematically investigates the system requirements for reconstructing impedance via the Fourier transform of voltage and current signals obtained upon current interruption. Using a calibrated equivalent circuit model, key parameters such as the minimum sampling interval $\Delta t_s$, the initial time collected during relaxation $t_i$, and the current removal duration $t_f$, are correlated with the frequency range [$f_{min}$,$f_{max}$] in which impedance is reconstructed within 1% error. A Gaussian window, whose width is modulated with frequency, effectively mitigates noise up to 0.1 mV. The resulting general relations, $f_{min} = 4/t_f$ and $f_{max} = 0.07/ \Delta t_s$ (or $f_{max} = 0.07/t_i$ for $t_i > \Delta t_s$), are valid within $10^{−2}–10^4$ Hz, that is sufficient to cover ohmic, polarisation, and diffusion impedance features. Experimental tests on a commercial lithium-ion cell corroborate the generality of these system requirements. With a sampling interval of 70 μs for $f_{max} = 10^3$ Hz and a waiting time of 40 s for $f_{min} = 10^{-1}$ Hz, the current interruption technique appears compatible with commercial instrumentation, making it potentially applicable for real-time impedance monitoring in operating lithium-ion batteries.