Analysis of Thermal Runaway Temperature Characteristics, Gas Composition, and Thermal Runaway Products of Semi-Solid Li(Ni0.6Co0.2Mn0.2)O2 Battery

Abstract In order to enhance the energy density of lithium-ion batteries (LIBs), semi-solid batteries, as a transitional product in the development of all-solid-state batteries, have garnered attention from numerous enterprises and research institutions. This study, through a designed experiment, triggers the thermal runaway (TR) of semi-solid Li(Ni0.6Co0.2Mn0.2)O2 (NCM622) batteries by lateral heating. The experiment utilizes a self-developed sealing device and a combination of temperature sensors and high-speed photography to record and analyze the temperature characteristics, gas emission characteristics, and emission morphology during the TR of the semi-solid NCM622 battery. Further research and analysis were conducted on the composition of the gas and products produced during TR. The results indicate that there is no apparent correlation between the severity of gas generation during TR and the rate of temperature rise. The highest temperature during battery TR can reach 950.33 °C, and the peak gas production rate can reach 300 L/s. The gas produced during TR mainly consists of CO, CO2, and H2, with CO accounting for up to 57.14%. The particulate matter produced during TR contains a large amount of organic elements such as C and O, as well as metal elements such as Ni, Al, Cu, and Co. This study fills a gap in the research content in the field of thermal safety of semi-solid LIBs, and the research data provide a reference for passive battery safety.