Internal monitorization and evaluation of specific 18650 Li-ion cells parameters by using tailored optical fiber sensors

Abstract

In this study, a tailored hybrid sensing configuration integrating fiber Bragg grating and intrinsic Fabry-Perot interferometer is presented. It enables simultaneous discrimination and tracking of internal temperature and pressure changes within 18650 Li-ion batteries (LiBs). The battery undergoes rigorous cycling tests at different operating conditions and a comparison between them is presented. The optical fiber sensors instrumented into the LiB reveal, throughout overall cycling tests, a compelling correlation between internal and external temperature behavior. The application of systematic Incremental Capacity Analysis derivative curves during battery operation exposes crucial insights into the relationship between pressure and temperature physical parameters, and their electrochemical behavior. This optical sensing approach contributes in this way to a nuanced understanding of internal LiB dynamics, with implications for their optimizing performance and safety in diverse applications.