Quantifying the temperature distribution and thermal characteristics of a 4.35 V LiCoO2/graphite pouch cell by modeling and experiments

Highlights: • An electrochemical-thermal model for 4.35 V LiCoO₂/graphite cells is validated. • The dU/dT shows a strong correlation with the S-shaped temperature rise curve. • Polarization heat plays a more significant role in the total heat generation. • Heat generated from cathode is 2 times larger than that originated from anode. -- Abstract: Understanding the temperature distribution and thermal characteristic is crucial for optimizing the thermal safety of lithium-ion batteries. Herein, an electrochemical-thermal coupling model of 4.35 V LiCoO₂/graphite batteries is established and validated for quantifying the temperature and heat generation characteristics. Through acquiring the internal resistance (R) and entropy coefficient (dU/dT) of the cell by experiments, the relationship between the S-shaped temperature curves and heat generation is revealed preliminary. The quantitative analysis of the reversible and irreversible heat, together with the heat generation rate of cathode, anode and separator further evidence that the irreversible heat occupies a dominant position in total heat generation. Furthermore, the heat generated from cathode (${\overline{Q}}_{\text{tot}\_\text{cathode}}$=45.7 kW m⁻³) occupies the dominant role among the cell components, which is 2 times larger than the anode (${\overline{Q}}_{\text{tot}\_\text{anode}}$=22.6 kW m⁻³). The evolution rules of heat generation demonstrated here in this work can provide deeper insights to guide the optimization strategies for lithium ion batteries.