Abstract To mitigate range anxiety, the energy density of lithium-ion batteries has been continuously improved. In ternary lithium batteries, adding nickel in cathodes or increasing the voltage efficiently boosts the energy density but also escalates the thermal runaway (TR) risks. However, how these factors affect battery material reactions under abuse and overall battery behaviour remains unclear. In this study, the TR characteristics and thermochemical reaction behaviours of battery materials in high-voltage systems (LiNi 0.6 Mn 0.2 Co 0.2 O 2 | Gr) and high-nickel systems (LiNi 0.9 Mn 0.05 Co 0.05 O 2 | Gr) with similar energy densities are compared and analyzed. The results indicate that the decomposition temperature of LiNi 0.9 Mn 0.05 Co 0.05 O 2 is lower than that of LiNi 0.6 Mn 0.2 Co 0.2 O 2 , resulting in a lower TR trigger temperature ( T 2 ) for the high-nickel system battery. Furthermore, the release of more oxygen from LiNi 0.9 Mn 0.05 Co 0.05 O 2 promotes a more thorough and intense reaction with the anode, leading to a higher peak temperature ( T 3 ) during TR. The gas venting behaviour of the high-nickel system battery is also more severe than that of the high-voltage battery. These results indicate that batteries with high-voltage systems show better thermal safety. Therefore, for ternary lithium batteries, increasing the nickel content in the cathode significantly reduces the battery’s safety performance, and increasing the battery’s operating voltage appears to be a promising design direction for high-energy–density batteries. This study provides guidance for the material design of high-energy–density batteries.
Xu et al. (Thu,) studied this question.