A novel pseudo two-dimensional model for NCM Liion battery based on electrochemical-thermal coupling analysis

The thermal state of the automotive Li-ion battery requires to be monitored by the thermal management system for safety purpose. This paper presents a pseudo two-dimensional model for a 18650 cylindrical Li-ion battery to estimate heat generation and predict the transient temperature at 2C discharge and charge rates based on the electrochemical-thermal coupling analysis. For experimental validation, the 18650 cylindrical lithium-ion battery cell is tested under high and low temperature alternation inside the closed chamber whose temperature is under control. Various kinds of heat generations of the battery at different working conditions are achieved during charging and discharging at a rate of 2C. The temperature change estimated by the model is in good agreement with the experimental data. Therefore, the proposed thermal model provides a reliable temperature estimation of Li-ion batteries, which is sufficient accurate for the thermal management of the automotive battery. Moreover, the calculation cost of the proposed thermal model is evaluated and proven to be small enough for engineering application in the thermal management.