Characterization of Thermal-Runaway Particles from Lithium Nickel Manganese Cobalt Oxide Batteries and Their Biotoxicity Analysis

Thermal runaway is one of the main causes of lithium-ion battery failure or even explosion, accompanied by the leakage of toxic substances into the environment. In the present work, a severe thermal-runaway process of commercialized LiNi0.6Mn0.2Co0.2O2 and LiNi0.8Mn0.1Co0.1O2 batteries was simulated, and the biohazards of the produced particles were discussed. Composition analysis revealed that thermal-runaway particles contained multiple toxic metallic and nonmetallic elements (Ni, Co, Mn, Al, Cu, S, Si, P, and F), accompanied by valence changes of Ni, Co, and Cu. More importantly, a typical microorganism, Escherichia coli, was chosen as the test organism, and the biotoxicity of thermal-runaway particles was assessed by the electrochemical method. Corresponding pristine cathode materials were analyzed and compared simultaneously. The results indicated that the thermal-runaway particles would cause instant inhibitions on bacterial respiratory activities in the range of 25-200 mg/L, and cell membrane damages were observed after exposure to thermal-runaway particles for 5 h, whereas the corresponding pristine cathode materials only exhibited minor effects on bacterial activities in the same conditions. Moreover, no significant inhibitory impacts were detected in thermal-runaway particles' supernatants, which excluded ion dissolution as a major factor to bacterial toxicity in the short time period. The generation of the superoxide anion indicated a dominant role of reactive oxygen species in the biotoxicity of thermal-runaway particles. The present study focuses on the toxic effect of particles from the thermal-runaway process of lithium-ion batteries, which has significant implications for spent batteries disposal and environment protection.