Embedded Fiber Optic Sensors for In Situ and In-Operando Monitoring of Advanced Batteries

Our team is developing an optically-based smart monitoring system prototype targeting batteries for advanced battery applications such as hybrid and electric vehicles (EVs). The system concept envisions fiber optic (FO) sensors embedded within Lithium (Li)-ion batteries to measure parameters indicative of cell state in conjunction with our low-cost, compact optical wavelength-shift detection technology and intelligent algorithms to enable effective real-time performance management and optimized battery design. Towards these goals, we have successfully made functional prototypes of Li-ion pouch cells with FO sensors embedded within the electrode stack during cell fabrication. The strong, interesting signals from these FO sensors obtained over charge-discharge cycles offer valuable information and features to enable more accurate cell state-of-charge (SOC) and state-of-health (SOH) estimation, and better understand cell electrochemical and aging processes. This paper presents initial results from these prototype cells and compares the results from internal FO signals to earlier results reported by our team on purely external configurations where the FO sensors were attached to the cell skin.