Diagnostic approach for high-energy lithium-ion batteries based on comprehensive understanding of degradation mechanisms

Abstract

Understanding the internal state of lithium-ion batteries is of utmost significance for both the battery management and battery reuse fields. Battery utilization without knowledge of its internal state gives rise to unexpected capacity drops or safety concerns. Unfortunately, despite the growing demand for efficient and safe battery use, studies for an accurate diagnosis of lithium-ion batteries are still in their infancy. Thus, this study focuses on understanding of comprehensive degradation mechanisms of lithium-ion batteries and suggestion of novel health indicator for monitoring the internal state of them. The way how batteries degrade under specific operating conditions significantly affect their remaining useful life. In particular, rapid capacity drops or failure issues despite similar capacity levels emphasize the importance of a health indicator to accurately evaluate the battery internal state. This study clarifies critical internal states affecting the cycle life of lithium-ion batteries and presents a novel health indicator: the Dominant degradation factors among Negative and Positive electrodes (DNP) score. DNP score can discern the cell states on divergent degradation paths. Specifically, batteries that suffered heterogeneous anode degradation displayed negative scores, revealing the aggravation of cycle performance. It allows the classification of cells with a potential risk of sudden death. Conclusively, the DNP score is expected to facilitate on-board battery management and efficient allocation of resources for the battery re-use industry by dealing with the cells that have poor internal states in advance.