Ultra-high temperature reaction mechanism of LiNi0.8Co0.1Mn0.1O2 electrode

Lithium-ion batteries have attracted much attention due to their high energy density and excellent power performance, and are gradually becoming the power source of electric vehicles. However, the safety issues dominated by battery thermal runaway remain a crucial obstacle that hinders lithium-ion batteries to have higher energy density and lower cost. The cathode material plays a critical role in the energy density and thermal runaway of batteries. To address this issue, this study explores the thermal decomposition mechanism of LiNi0.8Co0.1Mn0.1O2 electrode at above 1000 °C. Experimental results indicate that the LiNi0.8Co0.1Mn0.1O2 cathode together with the aluminum current collector generates immense heat at 1000–1200 °C. This reaction is quite like the thermite reaction, according to the data from XRD, XPS, and SEM & EDS tests. However, the oxygen donor comes from the LiNi0.8Co0.1Mn0.1O2 cathode. Full cell experiments confirm the existence of the thermal decomposition reaction that occurs at the LiNi0.8Co0.1Mn0.1O2 electrode at ultra-high temperature. The existence of this reaction at ultra-high temperature explains the heat release mechanism for the thermal runaway of high-energy lithium-ion batteries, extending our vision on the battery failure mechanisms. This finding will benefit better electrode design of lithium-ion batteries with reduced thermal runaway hazard. •The heat and gas production of NCM811 cathode above 1000 °C are explored.•The thermal decomposition reaction is summarized by XRD and XPS.•The reaction dynamics at spatial dimension are checked by SEM & EDS tests.•The morphology of the cathode after heating has noticeable zone distribution.