| Summary: | 碩士 === 國立聯合大學 === 環境與安全衛生工程學系碩士班 === 103 === Recently commercial lithium-ion batteries range from different sizes, shapes, capacities, electrolytes, and cathode materials, etc. have caused many incidents in normal use and storage conditions worldwide. This study utilized a customized-made closed testing instrument with pseudo-adiabatic condition to explore the thermal runaway reaction of commercial 18600 Li-ion batteries.
First, the blank tests were conducted to confirm the capabilitity of the homemade instruments. Then, eleven commercial batteries to with over-charged voltage (4.2V) were selected as the samples. Cathode materials made of LiCoO2, LiMn2O4, LiFePO4, LiNi0.8Co0.15Al0.05O2 and LiNixMnyCozO2 were contained in these lithium-ion batteries. Features of thermal harzards such as the onset temperature (Tonset), crucial temperature (Tcr), the self-heat rate (dT/dt), the maximum temperature (Tmax), and the maximum pressure (Pmax) are measured and assessed.
These results showed the ranking of thermal stability： LiFePO4 battery > LiMn2O4 battery >LiNi0.8Co0.15Al0.05O2 battery > LiNixMnyCozO2 battery > LiCoO2 battery. Most of the maximum temperatures within the batteries exceed both 650 ˚C and auto-ignition temperature (AIT) of organic carbonates to ignite the flammable vapors of the electrolytes in air. Adiabatic-temperature-rise is measured to be (533.6 ± 41.5) ˚C which equates to the enthalpy changes of (21.5 ± 1.9) kJ without adopting the correction of thermal inertia. Maximum self-heat rates are determined to be in the ranges between 5000 and 15000 ˚C min-1. Lithium-ion batteries compose of cathode materials made by LiCoO2, LiMn2O4 and LiNixMnyCozO2 shall carry the similarly calamitous characteristics under thermal runaway if they rise above the crucial temperature of (195.0 ± 20.0 ) ˚C. Apparatus of confinement test is proved to be a prominent tool for assessing the thermal hazards in lithium-ion batteries in this study.
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