A compact system for on-line electrochemical impedance spectroscopy on lithium-ion batteries

A compact measurement system for electrochemical impedance spectroscopy on lithium-ion batteries is presented. The system is composed of vector impedance analyzer (VIA) and state parameter estimation from raw impedance data. The VIA 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. The proposed measurement system aims at enabling on-line estimation of battery state parameters, like state-of-charge and state-of-health, through non-invasive electrochemical impedance spectroscopy technique.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 a good agreement. On-line discharge tests are also provided. These experimental results are then used for modeling purposes, showing that the proposed system is suitable for usage in conjunction with a battery management system for on-line monitoring of the battery cell, and future smart actuation on the battery operation for optimization of its performance and lifetime.