Influence of capacity and energy density of lithium-ion battery on thermal reaction during high rate charging

NCM ternary lithium-ion batteries have been widely used in electric vehicles. However, the negative impacts of increased energy density cannot be ignored, particularly the heat generation from batteries during high-rate charging. Further analysis is required on the heat generation problem in high energy density NCM batteries for safety. In this study, the thermophysical parameters of batteries with different energy densities are tested, then a heat generation model during charging is constructed based on Bernardi equation. Furthermore, two NCM batteries with different energy densities are selected to analyse the heat generation when the charging rate varied from 1 C to 4 C. The results show that under the same charging rate, heat generation in a higher energy density NCM battery is more evident, and the average heat generation rate can reach 2.36 times that of a lower one. In addition, factors that cause the increased heat generation in NCM batteries are quantified.