Lithium-Ion Battery Safety Evaluation by Quantifying Lithium Plating Degree Based on Pressure Signals

Lithium (Li) plating poses a major challenge to the thermal safety of lithium-ion batteries (LIBs). In this work, low N/P LIBs are constructed to induce controllable Li-plating, and thermal response tests are performed to correlate Li-plating degree with thermal safety characteristics. A quantitative descriptor of Li-plating degree (D_Li) is established, and post-mortem characterizations show that increasing D_Li is accompanied by the accumulation of Li-plating and side-reaction products, along with aggravated interfacial degradation. Based on the evolution of pressure signals during calibration, a non-destructive diagnostic model for D_Li is further developed. Accelerating rate calorimeter (ARC) results show that the first detectable self-heating temperature of low N/P cells decreases monotonically with increasing D_Li, indicating a progressively reduced thermal safety margin. Accordingly, D_Li thresholds of 20% and 30% are identified, and a thermal safety grading and battery management framework is established. Cross-scale validation in commercial 12 Ah cells shows that the predicted D_Li values and safety grades agree well with the observed thermal runaway behaviors. Overall, this work advances Li-plating assessment from occurrence identification to the quantitative diagnosis of Li-plating degree and the corresponding thermal safety grading. The proposed framework provides a basis for Li-plating risk assessment and safety evaluation of LIBs.