Detailed characterization of particle emissions due to thermal failure of batteries with different cathodes.

Sufficient levels of thermal, electrical, mechanical, or electrochemical abuse can cause thermal runaway in lithium-ion batteries, leading to the release of electrolyte vapor, combustible gas mixtures, and high-temperature particles. Particle emissions due to thermal failure of batteries may cause serious pollution of the atmosphere, water sources, and soil as well as enter the human biological chain through crops, posing a potential threat to human health. Furthermore, high-temperature particle emissions may ignite the flammable gas mixtures produced during the thermal runaway process, resulting in combustion and explosions. This research focused on determining the particle size distribution, elemental composition, morphology, and crystal structure of particles released from different cathode batteries after thermal runaway. Accelerated adiabatic calorimetry tests were performed on a fully charged Li(Ni0.3Co0.3Mn0.3)O2 battery (NCM111), Li(Ni0.5Co0.2Mn0.3)O2 battery (NCM523), and Li(Ni0.6Co0.2Mn0.2)O2 battery (NCM622). Results of all three batteries indicate that particles with a diameter less than or equal to 0.85 mm exhibit an increase in volume distribution followed by a decrease in volume distribution as the diameter increases. F, S, P, Cr, Ge, and Ge were detected in particle emissions with mass percentages ranging from 6.5% to 43.3%, 0.76-1.20%, 2.41-4.83%,1.8-3.7%, and 0-0.14%, respectively. When present in high concentrations, these may have negative impacts on human health and the environment. In addition, the diffraction patterns of the particle emissions were approximately the same for NC111, NCM523, and NCM622, with emissions primarily composed of Ni/Co elemental, graphite, Li2CO3, NiO, LiF, MnO, and LiNiO2. This study can provide important insights into the potential environmental and health risks associated with particle emissions from thermal runaway in lithium-ion batteries.

A comparative analysis on thermal runaway behavior of Li (NixCoyMnz) O2 battery with different nickel contents at cell and module level.

The problem of thermal runaway (TR) propagation challenges the safety design of battery packs, because it aggravates the thermal hazards to accidents. There are many unsolved scientific questions in understanding the mechanisms of TR and its propagation behavior for large format lithium-ion batteries (LIBs). LiNixCoyMnzO2(NCM) is considered as one of the most promising cathode materials for lithium-ion batteries LIBs, given its higher energy design and lower cost. However, higher Nickel (Ni) content of cathode material worsens the thermal stability of LIBs. This paper provides a comparative analysis on the TR propagation behavior of NCM battery with different Ni ratios. Results have shown that when the characteristic temperatures of TR {T1, T2, T3}and the specific electrochemical energy of the cell are similar, TR propagation behavior will be similar, no matter what kinds of chemistry the cell has. Observation suggests that the average propagation time within a large format cell is 7-10 s in module tests. Besides, the internal temperature of the cell has an order of NCM622 ≥ NCM523 ≥ NCM111,whereas the mass is ordered by NCM622 > NCM523 > NCM111.This work firstly reports the TR feature in large format LIBs with different Ni ratios, both at cell and module level, providing the guidelines for engineering practice and further theoretical researches.