In-Depth Investigation of Polarization Processes in Li-Ion Batteries through Distribution of Relaxation Times

Lithium-ion batteries (LIBs) play a critical role in modern energy storage systems, enabling their widespread use in portable electronics, electric vehicles, and grid-scale applications. However, accurately identifying and separating internal resistance components remains a significant challenge, limiting the optimization of battery performance and longevity. Here, utilizing the distribution of relaxation time (DRT) method, we deconvolute overlapping impedance components and analyze six distinct polarization processes within the battery system. This study demonstrates that the oxide solid electrolyte separator enhances ionic conductivity, thermal stability, and Li-ion transport, surpassing the performance of conventional PE separators. Furthermore, in situ DRT analysis identifies degradation mechanisms, emphasizing the critical role of charge transfer and diffusion resistance in performance decline. Collectively, these findings provide valuable insights into the origins of resistance factors in practical systems and offer a pathway to the development of high-performance LIBs with improved durability and efficiency.