In-situ Electrochemical Impedance Spectroscopy of Battery Cells by means of Binary Sequences

In this paper, the use of binary sequences for electrochemical impedance spectroscopy (EIS) of battery cells is experimentally investigated by implementing them on a VLSI 1-bit current digital-to-analog converter. Two types of binary sequences are considered, i.e. sigma-delta modulated multisine sequences and maximum-length binary sequences. Their performance is evaluated using a low-complexity experimental setup. Results prove that the two types of sequences are capable of estimating the complex impedance of a battery in the frequency range of interest 1 Hz-200 Hz with an RMSE smaller than 5% with respect to a reference instrument. Both sequences are suitable for implementing online in-situ EIS monitoring, because they enable fast measurement and simple integration within the battery cell itself.