Fiber Optic Monitoring of Composite Lithium Iron Phosphate Cathodes in Pouch Cell Batteries

Developing techniques for real-time monitoring of the complex and dynamic environment in lithium-ion batteries is crucial optimal use cells to develop next generation batteries. In this work, we demonstrate fiber optic evanescent wave (FOEW) sensors lithium iron phosphate (LFP) composite cathodes pouch cells. The were placed on top LFP electrodes, found cycle well with significantly improved electrochemical performance compared fully embedded fibers Swagelok Galvanostatic, voltammetric, pulsed current demonstrated that optical response correlated capacity, a clear difference sensor was seen when at surface electrodes cathode. from different rates also investigated, but no apparent influence intensity output even though polarization observed voltage profiles higher currents. It electrolyte itself functioned as cladding salt concentration did not signal. addition, given short penetration depth waves, most likely dominated by conditions electrode particles near sensing region. These findings provide further insight into application FOEW integrated batteries, possibility developing low-cost battery under working conditions.