Fabrication of Multimeasurand Sensor for Monitoring of a Li-Ion Battery

This paper details the fabrication and testing of a combined temperature and expansion sensor to improve state of charge (SOC) and state of health (SOH) estimation for Li-ion batteries. These sensors enable the characterization of periodic stress and strain changes in the electrode materials of Lithium-ion batteries during the charge and discharge process. These ultrathin sensors are built on a polyimide substrate which can enable direct integration between cells without compromising safety or cell cooling design. Leveraging the sensor design and fabrication process used to create inductive coil eddy current (EC) sensors for crack detection, these sensors were characterized on three Panasonic 5 A-h cells showing the capability to measure expansion of Li-ion batteries. By sensing the intercalation effects, which cause cell expansion, improvements in estimation of SOH and SOC can be enabled through the use of physics-based battery models, which combine the thermal, mechanical, and electrochemical aspects of its operation.