scholarly journals Experimental Analysis of Thermal Runaway in 18650 Cylindrical Li-Ion Cells Using an Accelerating Rate Calorimeter

2017 ◽  
Author(s):  
Boxia Lei ◽  
Wenjiao Zhao ◽  
Carlos Ziebert ◽  
Nils Uhlmann ◽  
Magnus Rohde ◽  
...  
Keyword(s):  
Internal Pressure ◽  
Lithium Ion ◽  
Pressure Change ◽  
External Pressure ◽  
Thermal Runaway ◽  
High Rate ◽  
Accelerating Rate Calorimeter ◽  
Exothermic Reactions ◽  
Pressure Line ◽  
Pressure Changes

In this work commercial 18650 lithium-ion cells with LiMn2O4, LiFePO4 and Li(Ni0.33Mn0.33Co0.33)O2 cathodes were exposed to external heating in an Accelerating Rate Calorimeter (es-ARC, THT Company) to investigate the thermal behavior under abuse conditions. New procedures for measuring external and internal pressure change of cells were developed. The external pressure was measured utilizing a gas-tight cylinder inside the calorimeter chamber in order to detect venting of the cells. For internal pressure measurements, a pressure line connected to a pressure transducer was directly inserted into the cell. During the thermal runaway experiments, three stages (low rate, medium rate and high rate reaction) have been observed. Both pressure and temperature change indicated different stages of exothermic reactions, which produced gases or/and heat. The onset temperature of thermal runaway was estimated according to temperature and pressure changes. Moreover, the different activation energies for the exothermic reactions could be derived from Arrhenius plots.

scholarly journals Degradation Reactions in SONY-Type Li-Ion Batteries

1999 ◽  
Vol 575 ◽  
Author(s):  
E. Peter Roth ◽  
G. Nagasubramanian
Keyword(s):  
Lithium Ion ◽  
Thermal Runaway ◽  
The State ◽  
State Of Charge ◽  
Reaction Products ◽  
Exothermic Reactions ◽  
Degradation Reactions ◽  
Lithium Ion Cells ◽  
Reaction Region ◽  
Charge Degree

ABSTRACTThermal instabilities were identified in SONY-type lithium-ion cells and correlated with interactions of cell constituents and reaction products. Three temperature regions of interaction were identified and associated with the state of charge (degree of Li intercalation) of the cell. Anodes were shown to undergo exothermic reactions as low as 100°C involving the solid electrolyte interface (SEI) layer and the LiPF6 salt in the electrolyte (EC:PC:DEC/LiPF6). These reactions could account for the thermal runaway observed in these cells beginning at 100°C. Exothermic reactions were also observed in the 200°C-300°C region between the intercalated lithium anodes, the LiPF6 salt, and the PVDF. These reactions were followed by a hightemperature reaction region, 300°C-400°C, also involving the PVDF binder and the intercalated lithium anodes. The solvent was not directly involved in these reactions but served as a moderator and transport medium. Cathode exothermic reactions with the PVDF binder were observed above 200°C and increased with the state of charge (decreasing Li content). This offers an explanation for the observed lower thermal runaway temperatures for charged cells.

scholarly journals A MECHANISM FOR TRANSPORT OF SUBSTANCES BY TEMPERATURE-INDUCED PRESSURE GRADIENTS

HortScience ◽  
1992 ◽  
Vol 27 (6) ◽  
pp. 626e-626
Author(s):  
Kenneth A. Corey ◽  
Zhi Yi Tan
Keyword(s):  
Internal Pressure ◽  
Pressure Change ◽  
Temperature Gradients ◽  
Diurnal Changes ◽  
Pressure Gradients ◽  
Tomato Plants ◽  
Temperature Changes ◽  
Soil Temperatures ◽  
Pressure Changes ◽  
Gas Pressures

Diurnal changes in air and soil temperatures lead to temperature gradients between air and soil, between roots and shoots, and within plant organs. In response to these gradients, fluctuations in gas pressures may develop in organs that are resistant to exchange of gases. These fluctuations may regulate mass flow of gases or solutions within plants. Patterns of diurnal temperature changes were generated to illustrate temperature gradients between roots and shoots. Experimental confirmation of pressure changes induced by temperature differences between roots and shoots were measured with water manometers attached to stumps of detopped tomato plants. When roots were maintained 8 C lower than shoots, internal pressure decreased by 22 cm H2O. Reversing the direction of the temperature gradient led to an approximately equal and opposite pressure change and to sap movement. These results support a hypothesis that internal pressure gradients resulting from temperature gradients contribute to transport of substances in plants.

scholarly journals Thermal runaway of Lithium-ion batteries employing LiN(SO2F)2-based concentrated electrolytes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Junxian Hou ◽  
Languang Lu ◽  
Li Wang ◽  
Atsushi Ohma ◽  
Dongsheng Ren ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Electrochemical Performance ◽  
Lithium Ion Batteries ◽  
Lithium Ion ◽  
Thermal Runaway ◽  
Exothermic Reactions ◽  
Safety Issues ◽  
Design Philosophy ◽  
Concentrated Electrolytes ◽  
Battery Material

Abstract Concentrated electrolytes usually demonstrate good electrochemical performance and thermal stability, and are also supposed to be promising when it comes to improving the safety of lithium-ion batteries due to their low flammability. Here, we show that LiN(SO2F)2-based concentrated electrolytes are incapable of solving the safety issues of lithium-ion batteries. To illustrate, a mechanism based on battery material and characterizations reveals that the tremendous heat in lithium-ion batteries is released due to the reaction between the lithiated graphite and LiN(SO2F)2 triggered thermal runaway of batteries, even if the concentrated electrolyte is non-flammable or low-flammable. Generally, the flammability of an electrolyte represents its behaviors when oxidized by oxygen, while it is the electrolyte reduction that triggers the chain of exothermic reactions in a battery. Thus, this study lights the way to a deeper understanding of the thermal runaway mechanism in batteries as well as the design philosophy of electrolytes for safer lithium-ion batteries.

scholarly journals Lithium-ion Battery Thermal Safety by Early Internal Detection, Prediction and Prevention

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Bing Li ◽  
Mihit H. Parekh ◽  
Ryan A. Adams ◽  
Thomas E. Adams ◽  
Corey T. Love ◽  
...  
Keyword(s):  
Temperature Rise ◽  
Lithium Ion ◽  
Current Collector ◽  
Thermal Runaway ◽  
Electrode Temperature ◽  
Exothermic Reactions ◽  
Electrode Current ◽  
Prediction And Prevention ◽  
Temperature Detector ◽  
Higher Temperature

Abstract Temperature rise in Lithium-ion batteries (LIBs) due to solid electrolyte interfaces breakdown, uncontrollable exothermic reactions in electrodes and Joule heating can result in the catastrophic failures such as thermal runaway, which is calling for reliable real-time electrode temperature monitoring. Here, we present a customized LIB setup developed for early detection of electrode temperature rise during simulated thermal runaway tests incorporating a modern additive manufacturing-supported resistance temperature detector (RTD). An advanced RTD is embedded in a 3D printed polymeric substrate and placed behind the electrode current collector of CR2032 coin cells that can sustain harsh electrochemical operational environments (acidic electrolyte without Redox, short-circuiting, leakage etc.) without participating in electrochemical reactions. The internal RTD measured an average 5.8 °C higher temperature inside the cells than the external RTD with almost 10 times faster detection ability, prohibiting thermal runaway events without interfering in the LIBs’ operation. A temperature prediction model is developed to forecast battery surface temperature rise stemming from measured internal and external RTD temperature signatures.

Influence of ambient pressure and heating power on the thermal runaway features of lithium-ion battery

2020 ◽  
pp. 1-24
Author(s):  
Xiantao Chen ◽  
Xu Zhang ◽  
Haibin Wang ◽  
Jingyun Jia ◽  
Song Xie ◽  
...  
Keyword(s):  
Heat Release ◽  
Lithium Ion Battery ◽  
Dynamic Pressure ◽  
Ambient Pressure ◽  
Lithium Ion ◽  
Fire Risk ◽  
External Pressure ◽  
Thermal Runaway ◽  
Heating Power ◽  
Low Oxygen

Abstract The thermal runaway hazards pose serious threat to the application and transport of lithium-ion battery on the aircraft. Hence the researches of thermal safety in flight condition are necessary. In this study, the tests were conducted in a dynamic pressure chamber to study the effects of ambient pressure and heating power on the thermal runaway characteristics. The results show that the fierce behaviors of jet fire, deflagration and explosion only were observed in high ambient pressure with high heating power. The open time of safety valve is advanced as pressure from 95 kPa to 20 kPa. The parameters of heat release rate (HRR), total heat release (THR), cell surface temperature, peak concentration of CO2 and mass loss decrease as the descend of external pressure or heating power. The peak values of hydrocarbon (CHx) and CO increase with the descent of pressure, but decrease as the reduction of heating power. The effects of ambient pressure on the thermal runaway (TR) fire behaviors mainly attribute to the low oxygen density. The time of heating and smoking may account for the difference of TR behaviors with various heating power. It is revealed that the fire risk and the hazards of toxic/flammable gas emissions are tightly relative to the TR behaviors. Those results provide valuable proposals and inspiration for the safety warning and hazard reduction under low pressure.

Heart Rate Signal Decomposition

2000 ◽  
Vol 39 (02) ◽  
pp. 200-203
Author(s):  
H. Mizuta ◽  
K. Yana
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Pressure Change ◽  
Normal Subjects ◽  
Signal Decomposition ◽  
Large Individual ◽  
Heart Rate Fluctuations ◽  
Type Pattern ◽  
Signal Cancellation ◽  
Pressure Changes

Abstract:This paper proposes a method for decomposing heart rate fluctuations into background, respiratory and blood pressure oriented fluctuations. A signal cancellation scheme using the adaptive RLS algorithm has been introduced for canceling respiration and blood pressure oriented changes in the heart rate fluctuations. The computer simulation confirmed the validity of the proposed method. Then, heart rate fluctuations, instantaneous lung volume and blood pressure changes are simultaneously recorded from eight normal subjects aged 20-24 years. It was shown that after signal decomposition, the power spectrum of the heart rate showed a consistent monotonic 1/fa type pattern. The proposed method enables a clear interpretation of heart rate spectrum removing uncertain large individual variations due to the respiration and blood pressure change.

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