Battery State of Charge Estimation using Guided Waves— Numerical Validation and Statistical Analysis

Abstract

This work presents a novel scalable and field deployable framework for estimating battery state of charge (SoC) based on pitch-catch guided wave propagation using lowprofile built-in piezoelectric transducers. A preliminary study is performed through experiments using piezoelectric disc transducers mounted on commercial lithium-ion (Li-ion) pouch batteries. Similar experiments are carried out on Multifunctional Energy Storage (MES) Composites, which are an energy-storing structural material recently developed by the authors. In this work, special emphasis is given to the numerical validation of the variation in guided wave time of flight (ToF) due to the SoC-induced changes in electrode mechanical properties. The experimental results are accurately captured in the numerical simulation, which provides significant insight on the complex coupling between electrochemistry and mechanics. Moreover, a first-pass statistical analysis is conducted which demonstrates the efficacy of using guided wave data to obtain accurate prediction of battery SoC. The study also reveals a promising opportunity for exploiting the feature-rich multi-path nature of guided wave propagation to further improve SoC prediction accuracy.