State of Health Estimation using Temperature Sensors during Charging in Li-ion Batteries

Accurate prediction of State of Health (SOH) is crucial to ensuring battery system performance and safety. Unlike traditional SOH estimation methods that are based on battery voltage and current, we propose using only surface temperature measurements. In this way, SOH can be estimated without requiring an interface to each cell's power terminals, using, for example, a temperature-sensing Radio Frequency Identification (RFID) tag that is bonded to the cell surface. An RFID-enabled charger or puck inside the pack can read the RFID tags at a high rate to measure the surface temperature and time history of every cell in the pack during constant current charging. SOH is estimated from the increase in surface temperature over the life of the battery due to the increase in resistance associated with aging. The proposed SOH estimation algorithm is validated with an open-source battery cycling dataset. We found a robust correlation between estimated and actual battery internal resistance, particularly under well-controlled ambient temperatures and fast charging.