Research on the Reversible and Irreversible Heat Generation of LiNi1−x−yCoxMnyO2-Based Lithium-Ion Batteries

Accidents involving fires and explosions caused by lithium-ion battery thermal runaway have severely hampered the development of electric vehicles. With the purpose of improving the safety of battery operation and avoiding thermal runaway of lithium-ion batteries. This work conducts a full-scale heat generation quantitative test of two types of LiNi1−x−yCoxMnyO2-based commercial batteries by measuring the voltage-temperature coefficient (dE/dT) and the overpotential using the galvanostatic intermittent titration technique (GITT). Results indicate that that the heat generation rates of the two types of batteries exhibit similar trends. Battery heat generation is a function of C-rate, temperature and state of charge. Among them, C-rate is the most important influencing factor. The reversible heat contribution is the most significant at higher temperatures and lower C-rates. In most cases, the irreversible heat accounts for the dominant contribution to the total heat generation. The contribution of heat generation due to mass transport limitation is dominant among irreversible heat, and it is more significantly affected by temperature and state of charge, whereas the ohmic contribution shows a minor impact. The detailed analysis of the reversible and irreversible heat generation can provide effective theoretical guidance for safety warning and fire protection of lithium-ion battery systems, minimize the probability of the risk of fire accidents of the lithium-ion battery.