Thermal safety assessment of lithium-ion batteries based on direct current impedance during the whole lifecycle

The intricate side reactions inside lithium-ion batteries during the operational lifespan frequently leads to safety concerns despite suffering from rigorous standard testing. There is an urgent need to conduct real-time assessments of battery thermal safety throughout the whole lifecycle. However, there is a significant scarcity in current methods for assessing thermal safety of lithium-ion batteries during the whole lifecycle. This work introduces an innovative method for online non-destructive assessment of battery thermal safety throughout the whole lifecycle based on direct current impedance. By analyzing the thermal runaway characteristics and direct current impedance properties of lithium-ion batteries under different degradation paths, a robust correlation between the activation energy during the direct current pulse process and the self-heating initial temperature has been established. Based on this, the thermal safety of lithium-ion batteries can be assessed accurately and quickly by online acquisition of the activation energy of the direct current pulse process. Furthermore, the accuracy of this assessment method is validated through by other experiments under different degradation paths. [Display omitted] •Battery thermal safety under various aging paths is tested.•Activation energy of the pulse process under various aging paths is analyzed.•The battery safety risks are quantified and classified.•Mapping relationship between thermal safety and activation energy is established.•Thermal safety assessment method based on DC impedance is developed.