Evaluating the heat generation characteristics of cylindrical lithium-ion battery considering the discharge rates and N/P ratio

Although lithium-ion batteries (LIBs) have received more attentions as the increasing number of new energy vehicles, in-depth exploration for the heat generation characteristics of LIBs during operation remains challenging. This paper establishes an electrochemical-thermal model (ETM) to evaluate the heat generation characteristics of cylindrical LIBs considering the discharge rates and the ratio of negative to positive electrode capacity (N/P ratio). To ensure a wider range of research on thermal characteristics of LIBs, the proposed ETM is validated based on the experimental data under the ambient temperature of 25 °C and 35 °C. Subsequently, the distribution profiles of heat generation characteristics of LIBs under different conditions are numerically investigated. More innovatively, the effects of different discharge rates and N/P ratios on battery heat generation are comprehensively analyzed. The results show that the heat generation in the negative electrode occupies a major part and the influences of reversible term on the total heat generation of LIB cell cannot be ignored, especially at low discharge rates. Additionally, it is found that the proper selection of N/P ratio can improve the total heat generation of LIBs, which is helpful for optimizing performance in the early stages of battery design and thermal management.