Thermal Runaway Prediction of Lithium-Ion Battery Based on Impedance Online Measurement

Thermal runaway of lithium-ion batteries will cause significant irreversible damage to the energy storage system. Thus, early prediction of thermal runaway is very important. In this paper, a thermal runaway method based on the trend of cell impedance changing with temperature and the distribution of the impedances of the cells in battery pack is proposed. With this method, the distribution of battery impedances, not just the variation of a single battery impedance, is used for predicting thermal runaway, which will improve prediction reliability. The impedance measurement system for battery cells in a battery pack is introduced and the multi-level warning method of thermal runaway based on fuzzy controller is introduced. The experimental results indicate that the higher the battery temperature, the smaller the impedance and the closer the cell is to the high-temperature cell, the lower the impedance of the cell. Based on the above characteristics, thermal runaway prediction can be achieved.