Fiber Bragg Grating -Based State of Charge Sensitive Feature Extraction and Estimation for Lithium Ion Batteries

Traditional voltage- and current-based SOC estimation methods are susceptible to electromagnetic interference and dependent on model accuracy. To address this challenge, this work monitors the temperature and strain of graphite anode in Lithium Iron Phosphate (LFP) pouch cell based on FBGs to obtain richer physicochemical information. The mechanical strain is creatively separated from measured strain as a SOC feature and shown to have stronger correlation and linearity with SOC. We construct a framework for SOC estimation based on the extracted feature with a Root Mean Square Error (RMSE) less than 1.5% under dynamic loading.