Internal temperature detection of thermal runaway in lithium-ion cells tested by extended-volume accelerating rate calorimetry

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.

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Investigation on Thermal Runaway of Li-Ion Cells Based on LiNi1/3Mn1/3Co1/3O2

Journal of Electrochemical Energy Conversion and Storage ◽

10.1115/1.4048329 ◽

2020 ◽

Vol 18 (3) ◽

Author(s):

Xiaoyi Xie ◽

Dongsheng Ren ◽

Li Wang ◽

Xuning Feng ◽

Xiangming He

Keyword(s):

Electric Vehicles ◽

Safety Management ◽

Lithium Ion ◽

Thermal Runaway ◽

Onset Temperature ◽

Ex Situ ◽

X Ray Diffraction ◽

Self Heating ◽

Lithium Ion Cells ◽

Endothermic Reactions

Abstract The thermal runaway behavior of lithium-ion cells plays a crucial role in the safety management of the powertrain in electric vehicles. In this study, the effect of states of charge (SOC) on the thermal runaway behavior of commercial LiNi1/3Mn1/3Co1/3O2 (NMC)-based pouch cells is investigated using accelerating rate calorimetry (ARC) and ex-situ X-ray diffraction. By studying the differences in the onset temperature of self-heating (T1) and the onset temperature of thermal runaway (T2) along with the mass loss between the different SOCs, we observed that higher SOC led to a decrease in the T2. However, T1 initially increased and then decreased with increasing SOC. These trends were attributed to the phase change of cathode material and separator. The ARC results also indicated the occurrence of endothermic reactions during the self-heating accumulation period. The findings in this study are helpful for thermal safety management of battery powertrain for electric vehicles.

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Influence of aging on the heat and gas emissions from commercial lithium ion cells in case of thermal failure

Journal of Electrochemical Science and Engineering ◽

10.5599/jese.476 ◽

2018 ◽

Vol 8 (1) ◽

pp. 101-110 ◽

Cited By ~ 5

Author(s):

Michael Lammer ◽

Alexander Königseder ◽

Peter Gluschitz ◽

Viktor Hacker

Keyword(s):

Early Stage ◽

Lithium Ion ◽

High Energy ◽

Heat Emission ◽

Thermal Runaway ◽

Gas Composition ◽

Thermal Failure ◽

Energy Applications ◽

Lithium Ion Cells ◽

Li Ion

A method for thermal ramp experiments on cylindrical 18650 Li-ion cells has been established. The method was applied on pristine cells as well as on devices aged by cyclisation or by storage at elevated temperature respectively. The tested cells comprise three types of LiNi0.8Co0.15Al0.05O2 cells for either high power or high energy applications. The heat flux to and from the cell was investigated. Degradation and exothermic breakdown released large amounts of heat and gas. The total gas and heat emission from cycled cells was significantly larger than emission from cells aged by storage. After aging, the low energy cell ICR18650HE4 did not transgress into thermal runaway. Gas composition changed mainly in the early stage of the experiment. The composition of the initial gas release changed from predominantly CO2 towards hydrocarbons. The thermal runaway emitted for all tests a comparable mixture of H2, CO and CO2.

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Discharge by Short Circuit Currents of Parallel-Connected Lithium-Ion Cells in Thermal Propagation

Batteries ◽

10.3390/batteries5010018 ◽

2019 ◽

Vol 5 (1) ◽

pp. 18 ◽

Cited By ~ 3

Author(s):

Sascha Koch ◽

Alexander Fill ◽

Katerina Kelesiadou ◽

Kai Birke

Keyword(s):

Equivalent Circuit ◽

Short Circuit ◽

Equivalent Circuit Model ◽

Lithium Ion ◽

Thermal Runaway ◽

Circuit Model ◽

Test Series ◽

Lithium Ion Cells ◽

Short Circuit Currents ◽

Thermal Propagation

The increasing need for high capacity batteries in plug-in hybrids and all-electric vehicles gives rise to the question of whether these batteries should be equipped with a few large capacity cells or rather many low capacity cells in parallel. This article demonstrates the possible benefits of smaller cells connected in parallel because of discharge effects. Measurements have been conducted proving the beneficial influence of a lower SoC on the thermal runaway behaviour of lithium-ion cells. A second test series examines the short circuit currents during an ongoing thermal propagation in parallel-connected cells. With the help of a developed equivalent circuit model and the results of the test series two major system parameters, the ohmic resistance of a cell during thermal runaway R tr and the resistance post thermal runaway R ptr are extracted for the test set-up. A further developed equivalent circuit model and its analytical description are presented and illustrate the great impact of R ptr on the overall discharged capacity. According to the model, cells with a capacity of no more than C cell = 10–15 Ah and a parallel-connection of 24 cells show the most potential to discharge a significant amount.

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