Operando Monitoring of Chemo-Mechanical Stress Evolution in SiO/C Composite Anodes via Optical Frequency Domain Reflectometry

The cycling performance of lithium-ion batteries is closely related to the expansion effect of anode materials during charge and discharge processes. Studying the chemo-mechanical stress evolution of SiO/C composite anode materials is crucial for evaluating battery performance. Here, we propose a high spatial resolution phase-sensitive optical frequency domain reflectometry technique, in which the fiber under test is embedded into the anode of a lithium-ion battery to monitor the chemo-mechanical stress evolution during cycling with a spatial resolution of 1.5 mm. We investigated the stress under different loading levels and used this method to infer the morphological changes of the material. Furthermore, combining this with battery capacity information provides an approach for assessing the performance of lithium-ion batteries.