A Comparative Analysis on Thermal Stability of Delithiated Nickel-Rich LiNi0.8Co0.15Al0.05O2 and LiNi0.8Co0.1Mn0.1O2 in Pouch Cells

Abstract As two typical nickel-rich layered oxide cathodes, LiNi0.8Co0.15Al0.05O2 (NCA) and LiNi0.8Co0.1Mn0.1O2 (NCM811) are widely applicated in commercial high-energy batteries for electric vehicles. However, a comprehensive assessment of their thermal characteristics in a full cell is currently lacking. In this article, we conducted a monomer level thermal runaway test on NCA|SiC pouch cell and NCM811|SiC pouch cell through the accelerated rate calorimetry (ARC) test. The results showed that the {T1, T2, T3} of NCA|SiC pouch cell and NCM811|SiC pouch cell are {113.8 °C, 230.4 °C, 801.4 °C} and {91.3 °C, 202.1 °C, 745 °C}, respectively. Then the thermal stability of NCA and NCM811 was tested by differential scanning calorimeter coupled with thermal gravimetric analysis, and mass spectrometry (DSC-TG-MS). The results showed that the phase transition temperature of NCA is higher than that of NCM811. However, when NCA and NCM811 were mixed with anode electrode materials or electrolyte, NCA produced significantly more heat than NCM811. By confirming the thermal properties of NCA|SiC pouch cell and NCM811|SiC pouch cell, a deeper understanding of battery thermal runaway was achieved, which is helpful for the design of high-safety lithium-ion batteries in the future.