Experimental study on the runaway behaviors of Panasonic 21,700 LiNi0.8Co0.15Al0.05O2 battery used in electric vehicle under thermal failure

Journal of Thermal Analysis and Calorimetry - Thermal runaway phenomena of the Panasonic 21,700 LiNi0.8Co0.15Al0.05O2 lithium-ion batteries with 100, 50 and 25% capacity were studied under thermal...     

Thermal decompositions of dialkyl peroxides studied by DSC

Studies on the thermal decompositions of diamyl peroxide (DAPO), dicumyl peroxide (DCPO), and tert-butyl cumyl peroxide (TBCP) were conducted by DSC. Heat of decomposition, exothermic onset point, and chemical kinetics were determined and compared to those data of di-tert-butyl peroxide (DTBP), a model compound for studying thermokinetics of organic peroxide and standardization of a calorimeter. Similarities and differences of decomposition mechanisms between these organic peroxides were proposed and verified. Kinetics on decomposition of uni-molecular reaction via these similar alkoxyl radials accompanying β C–C bond scission were discussed and compared to the results from ab initio calculations. The ranking of thermal stability on dialkyl peroxides is determined to be in the following sequence: DCPO < TBCP < DAPO < DTBP. This rate-determining step in thermal decomposition of dialkyl peroxides possessed an average eigenvalue of log A at about 13.1 ± 1.2. Activation energy on the thermal decomposition of these peroxides was calculated to be 139.5 ± 14.4 kJ mol^?1.     

Thermal instabilities of organic carbonates with discharged cathode materials in lithium-ion batteries

Thermal instability of lithiated cathode materials with organic carbonate were investigated using DSC. Lithium transition metal oxides of LiFePO₄, LiMn₂O₄, and LiCoO₂ were mixed with diethyl carbonate, dimethyl carbonate, ethylene carbonate, ethyl methyl carbonate, and propylene carbonate then dynamically screened to about 500 °C. Curves were acquired and analyzed to determine exothermic onset temperatures and reaction enthalpies. These data for assessing the thermal hazards of lithium-ion batteries under discharged conditions were compared to those data published in the literature.     

Experimental investigation and visualization on thermal runaway of hard prismatic lithium-ion batteries used in smart phones

Journal of Thermal Analysis and Calorimetry - In this study, we demonstrate first time the application of confinement tests under excessive heating to track the thermal responses during the thermal...     

Thermolysis and analysis of TDI char by supercritical methanol using TGA,DSC, IR and SEM

Journal of Thermal Analysis and Calorimetry - TDI's synthetic plant generates about 5 mass % of tar by phosgenation process, which has been currently a bottleneck needed to be broken through...     

Thermal instabilities of organic carbonates with charged cathode materials in lithium-ion batteries

Thermal instabilities of de-lithiated materials with organic carbonates were verified by DSC. Transition metal oxides FePO₄, NiO₂, Mn₂O₄, and Co₃O₄ were mixed with DEC, DMC, EC, EMC, and PC then dynamically screened to about 500 °C. Curves were acquired and analyzed to determine exothermic onset temperatures and reaction enthalpies. These data for assessing the thermal hazards of conditions were compared to those data published in literature.     

Evaluation of thermal hazard for commercial 14500 lithium-ion batteries

Commercial lithium-ion batteries ranged from different sizes, shapes, capacities, electrolytes, anode and cathode materials, etc. have recently caused many incidents under abusive or normal operating conditions worldwide. Inherently safer designs with active or passive protections have became the captious issues that need more attentions paid to. In this study, the worst scenarios on thermal runaway of four commercial batteries were conducted and compared. A customized-made closed testing instrument was utilized to measure and track thermal behaviors of four brands of cylindrical lithium-ion batteries under maximum open circuit voltage condition. Characteristics on thermal hazards of lithium-ion batteries such as onset temperature, maximum temperature, maximum self-heat rate, maximum pressures, battery mass loss, etc. were measured and evaluated. Results point out that one brand of cells reached the maximum temperature and maximum self-heat rate of 590.9 K and 1,130.4 K min^?1, respectively. In conclusion, in case of thermal runaway all the lithium-ion batteries will rupture the cell and catch fire automatically owing to the maximum temperatures over the auto-ignition temperature of electrolytes and the maximum pressure higher than four times of maximum allowable working pressure, respectively. In addition, Lithium-ion battery with cathode material of LiFePO₄ was verified to be more stable than the lithium-ion battery with cathode material of LiMn₂O₄ or LiCoO₂.     

Thermal behaviors of electrolytes in lithium-ion batteries determined by differential scanning calorimeter

Lithium-ion batteries have been widely used in daily electric appliance, but abusive accidents occurred from time to time. Lithium-ion batteries composed of various electrolytes (containing organic solvents, inorganic salts), binder, and electrode materials, which may be unstable under some abnormal conditions. The formulation or components of electrolytes played a crucial factor in affecting reactive hazards within the cell. In order to meet safety requirements of the lithium-ion batteries on electronic device, reseachers and scholars are continuing to do further studies on the important issues in relation to the lithium-ion batteries. This study aims to apply the differential scanning calorimeter for measuring the thermal or reactive hazards of the organic solvents related to the formulation of the electrolytes. Besides, thermal instabilities of lithiated graphite or deposited lithium with electrolytes were simulated by the reactions between metallic lithium (Li) and organic carbonates of linear and cyclic structures. Exothermic onset temperatures and enthalpy changes were measured and analyzed. Results showed that the thermal behaviors of these organic carbonates themselves or with lithium hexafluorophosphate liberated less enthalpy changes. However, violent exothermic reactions were detected between the linear or cyclic carbonates and lithium metal with larger enthalpy change larger than 1,000 J g^?1 of lithium. This can be observed by Li reacted with diethyl carbonate at surprisingly lower onset temperature about 46.6 °C.     

Novel validation on pressure as a determination of onset point for exothermic decomposition of DTBP

Exothermic decomposition of di-tert-butyl peroxide (DTBP) was measured and assessed for determination of onset or threshold point which is essential for hazard evaluation or early detection of runaway reaction. Thermal decomposition of DTBP was conducted by differential scanning calorimeter and thermal scanning unit. Criteria of onset points are determined by and compared by the deflection curve of exothermic behavior (or heat flow), selected pressure, self-heat rate, or pressure-rising rate, respectively. Exothermic onset temperature of DTBP can be determined as low as 73.5 °C by pressure selected at 1.5 bar. Onset point determined by selected pressure is more sensitive and superior to the onset temperature traditionally measured by thermal analysis, adiabatic calorimetry using heat-wait-search methodology or theoretical approaches.