Internal Sensor based Li-ion Battery Safety Examination and Thermal Runaway Early Prevention
The reliability of Li-ion batteries (LIBs) is essential for electric vehicles (EVs) safety due to the fast charging/discharging, environmental dynamic loads and high temperature usage involved in LIB service. Among the LIB safety hazards, thermal runaway is recognized as the most critical one due to its rapid development and severe safety threat. Nowadays, the most common safety monitoring method is to measure the surface temperature and disconnect the LIBs when it reaches the threshold. Due to the thermal resistance, measurement on the battery surface cannot reflect the electrode temperature, which is crucial for LIB safety. Besides, most existing surface temperature-based LIB safety management methods neglect the difference in different abusing conditions and cannot provide customized LIB management. In our work, resistance temperature detectors (RTDs) were embedded into LIBs with additive manufacturing. The internal RTDs enabled electrode temperature measurement without disturbing battery operation, and thermal runaway risk was analyzed in the first place. Electrode and battery surface temperature were collected in short circuit and overcharge, which helped to compare thermal runaway under different abusing conditions. In both cases, the internal RTD detected the thermal runaway ~10 times faster than the external RTD, providing the opportunity for LIB failure prevention at an early stage. The temperature history of graphite anode and LiCoO2 cathode were compared to identify the critical electrode and optimize the temperature measuring methods. The internal sensor also improved the effectiveness of surface temperature-based LIB safety management. Fingerprints in battery surface temperature before catastrophic failure were recognized, which enabled early thermal runaway prevention with external sensors. Finally, case-specific strategies for LIB thermal runaway prevention from overcharge and short circuit were developed. By applying internal RTDs, the efficiency of thermal runaway detection was improved, and LIB service reliability was enhanced. Customized LIB safety management was developed for conventional surface temperature measurements.