Quantitative study on the thermal failure features of lithium iron phosphate batteries under varied heating powers

Insights into thermal failure features under varied heating powers are significant for the safe application of lithium ion batteries. In this work, a series of experiments were conducted to investigate the thermal failure features of fully charged lithium iron phosphate battery by means of copper slug battery calorimetry. Batteries were given a total quantity of external heat (16 kJ) under various heating powers (20-200 W). Battery temperatures, onset time of venting, mass loss and internal heat generation were measured and analyzed. Results show onset times of venting and thermal runaway both decrease exponentially with increasing heating power. Heat generation of batteries under different heating powers is in the range of 10.38 kJ - 15.07 kJ. The battery maximum temperature and heat generation do not increase monotonically with heating power, but reach the highest at 100 W. Furthermore, the experiments at 20 W with continuous heating were carried out to contrast with the experiments results of fixed heating quantity. It is found that battery maximum temperature, mass loss and heat generation are all higher under continuous heating. These encouraging results could enhance our understanding of thermal failure features and provide references for the safety design and thermal failure propagation prevention in battery module.

Automated summary

This study conducted a series of experiments to investigate the thermal failure features of a fully charged lithium iron phosphate battery under different heating powers, revealing that the onset times of venting and thermal runaway decrease exponentially with increasing heating power. The heat generation of the batteries ranges from 10.38 kJ to 15.07 kJ, with maximum temperature and heat generation reaching the highest at 100 W. Further experiments at a continuous heating power of 20 W showed higher maximum temperature, mass loss, and heat generation compared to experiments with fixed heating quantities.