Lithium-ion battery health prognosis via electrochemical impedance spectroscopy using CNN-BiLSTM model

Abstract

<p>Lithium-ion battery (LIB) health prognosis is essential for ensuring the safety of electric vehicles while they are in use. However, conventional approaches for accurate health state forecasting face challenges due to the complex interplay of battery degradation mechanisms and the significant variability in operating conditions during cycling. In this study, we propose a data-driven method composed of convolutional neural networks (CNNs) and bidirectional long short-term memory (BiLSTM) to accurately predict the state of health and remaining useful life of LIBs. The model is trained using a well-established open-source electrochemical impedance spectroscopy (EIS) database. This database includes over 20,000 EIS spectra from commercial LIBs, collected under various states of health, states of charge and temperatures. The CNN-BiLSTM model surpasses the previous state-of-the-art Gaussian process method in current capacity estimation and remaining useful life prediction. Furthermore, we showcase the model’s capability to forecast the capacity degradation trajectory of a cell using its early-cycle EIS data. Our research demonstrates the versatility of the battery forecasting method by integrating EIS with machine learning, and emphasizes the value of implementing the EIS-based artificial approach in a battery management system.<br></p>