An aging-aware modified open-circuit potential electrode model for degradation modes diagnosis of lithium titanate oxide batteries

Abstract

As the demand for lithium titanate oxide (LTO) batteries increases in high-power applications, their health estimation, especially the degradation mode diagnostics, is critical for the safe and economical operation of battery systems. However, various operation and environmental conditions can alter the aging of LTO cells, with few related studies. In this study, the changes in the electrode open-circuit potential (OCP) after aging are investigated and their effects on the full-cell open-circuit voltage (OCV) are discussed. An aging-aware modified electrode model is developed to simulate the evolution of the electrode OCP and used to diagnose the degradation mode by reconstructing the full-cell OCV curve. Unlike traditional polynomial models that lack physical meaning, the proposed aging-aware modified model reveals the changes in the phase transition process by identifying the warping paths of the incremental capacity curves. Compared with using only the pristine or aged OCP curves, using the synthesized OCP curves from the proposed model improves the accuracy of reconstructing full-cell OCV curves over the full life cycle, reducing the average RMSE from 80 mV to less than 8 mV. Moreover, the proposed model improves the validity of degradation mode diagnosis and adapts to different cycling conditions and different battery samples.