Online EIS and Diagnostics on Lithium-Ion Batteries by Means of Low-Power Integrated Sensing and Parametric Modeling

This article presents a compact measurement system for electrochemical impedance spectroscopy (EIS) on lithium-ion battery (LIB). The system is composed of a vector impedance analyzer (VIA) and state parameter estimation. The VIA architecture is based on delta-sigma digital-to-analog and analog-to-digital conversions to achieve the compactness, low-power consumption, and high resolution required to be potentially integrated within a battery cell. The estimation of state parameters is based on equivalent circuit models and the solution of nonlinear optimization problems. The proposed measurement system aims at the integration of complex measurement features directly into the battery cell to allow online and real-time diagnostic of the battery cell. A prototype of the compact measurement system was realized to assess the proposed approach. Experimental results are provided and validated by comparison with a reference laboratory instrument, showing good agreement. The VIA prototype is experimentally tested in both the online monitoring and aging monitoring of a commercial LIR2032 LIB cell. The modeling approach is applied to the experimental data provided by the VIA prototype, showing a good fit of the data. Moreover, parameters of the equivalent circuit models are extracted from the experimental data provided by the VIA prototype and identify trends related to the state of charge of the battery.