Runaway Of Lithium-ion Batteries Research Articles

Quantification of lithium deposition under mechano-electrochemical coupling effect

The non-uniform growth of lithium dendrites is the main factor causing internal short-circuits and thermal runaway in lithium-ion batteries. Due to the internal environment of the battery being a complex multi-field coupling, the mechanisms of triggering lithium deposition are still unclear. Here, a cross-sectional in-situ optical microscope device was fabricated to observe lithium dendrite evolution. The amount of irreversible and reversible lithium was quantified by the image binarization method and titration gas chromatography, which is used to analyze the relationship between separator deformation, current density, and lithium deposition. The greater the separator deformation and current density, the more irreversible lithium increases. The pore defect mapping algorithm was developed to reconstruct a high-precision three-dimensional finite element model of the separator, which was used to quantify the relationship between displacement loading and the microstructure evolution. A three-dimensional lithium deposition model was established on the actual microstructural parameters of the separator, predicting the concentration and electrochemical field of lithium deposition processes. A phase diagram of lithium precipitated failure in lithium-ion batteries with mechano-electrochemical coupling was developed with silicon-graphite electrode. This work will provide a new direction for understanding the mechanism of lithium deposition and guidance for commercial battery design.

(Invited) Culprits or Collateral Damage? The Science behind Lithium-Ion Battery Failure Investigations

Thermal runaway failures of lithium-ion batteries have garnered a great deal of attention in recent years, including notable failures in the spaces of consumer products, electric vehicles, and energy storage systems. The growing public awareness of hazards associated with thermal runaway in lithium-ion batteries has coincided with increased scrutiny of lithium-ion batteries when they are found at fire scenes. Lithium-ion batteries can go into thermal runaway due to heating from an external fire, even if they are not the cause of the fire. As always, the fire investigator and other experts involved in the failure analysis need to remain guided by the scientific method when performing an origin and cause analysis, including when that analysis involves lithium-ion batteries.This presentation will encompass many of the tools and reasoning that may be relied upon when analyzing the role lithium-ion batteries at fire scenes, as well as in the post-scene analysis of batteries and battery-containing devices. Techniques for understanding heat release and heat release rate during thermal runaway failures will be discussed, as well as the associated literature that may be relied upon to estimate heat release based on chemistry and capacity of the cells in question. Also to be discussed are metallurgical approaches and techniques that may inform the conditions that likely existed during the failure of the battery.

Modeling Competitive Reaction Heat Sources and Variable Cooling Rates Applicable to Thermal Runaway Onset in Lithium-Ion Batteries

Two main types of exothermic processes are known to initiate thermal runaway in Lithium-Ion batteries. If mechanical failure of the separator causes an electrical short circuit, the cell’s energy can be released through electrochemical discharge reactions. The full stored energy can be released as heat within the cell for internal short circuits, raising the cell temperature by several hundred degrees Celsius. Different thermochemical reactions occur when Lithium-Ion cells are heated; the anode and cathode materials decomposing with the electrolyte can result in similarly large temperature rises. Our work shows that thermodynamics constrain key reactant species for both decomposition paths to be in common. Interactions and competition between these chemical pathways for heat release are considered in this modeling study, including relative magnitudes of thermal contributions from each reaction pathway and limiting reactant effects. An effective oven temperature concept is defined, which allows thermal runaway initiation via internal short circuits versus external heating to be compared. Temperature and reaction inhomogeneities occurring in the presence of internal localized internal short circuits lead to variations in the balance between electrochemical and thermochemical reactions across the domain of the cell. A simple homogeneous analysis is compared to a higher-dimensional inhomogeneous analysis. The effectiveness external cooling strategies to mitigate an internal short circuit event is investigated. Acknowledgements: This article has been authored by an employee of National Technology & Engineering Solutions of Sandia, LLC under Contract No. DE-NA0003525 with the U.S. Department of Energy (DOE). The employee owns all right, title and interest in and to the article and is solely responsible for its contents. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this article or allow others to do so, for United States Government purposes. The DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan https://www.energy.gov/downloads/doe-public-access-plan. This abstract has been approved for release as SAND2023-01585A.

Identifying Thermal Decomposition Mechanisms of the Solid Electrolyte Interphase with in-Situ Gas Analysis of Lithium-Ion Batteries

The global shift away from fossil fuels has generated an unprecedented demand for electric vehicles and a steady increase in the prevalence of lithium-ion batteries. Additionally, increases in the energy density of storage technologies has led to a corresponding increase in safety concerns regarding thermal runaway reactions. The components of a lithium-ion battery can self-react when exposed to an external heat source, which can cause a thermal runaway reaction process and large-scale fires of the cell. The initial reactions in this process involve the decomposition of the Solid Electrolyte Interphase (SEI) breakdown and conductive salt. The underlaying mechanisms behind these reactions are unclear; in-depth investigations are needed in order to develop a detailed understanding of the thermal runaway process and guide the development of strategies to mitigate the safety hazards posed by these battery systems. In the past, differential/online electrochemical mass spectrometry (DEMS/OEMS) was utilized to analyze the buildup of the SEI as well as decomposition due to overcharge. Our new methodology of high temperature (HT-)OEMS, with a maximum temperature of 132 °C, can simulate heating events with thermal ramps on an in-situ test cell battery. These measurements reveal information regarding reaction product gases and cell voltage drop during first formation and thermal stress tests, and provide novel insight into the electrochemical and thermodynamic phenomena during thermal abuse of lithium-ion batteries.In this study, we use (HT-)OEMS to investigate the behavior of lithium-ion cells with varied additive concentrations and formation currents. This new methodology allowed us to clearly determine that both of the testing parameters impact the formation gas evolution and thus influence the SEI-composition. Systems with high formation rates, as well as with lower concentrations of additives, exhibited an increase in the fraction of CO product gases, which can be explained with a higher presence of lithium alkoxides in the SEI. Additionally, the evolution of H2, CO2 and POF3 gases were observed at temperatures around 80 °C for cells during the thermal stress test after formation. These results allow us to establish a correlation between the thermal conductive salt decomposition and the formation of the SEI-components Li2CO3 and (CH2OLi)2.The identification of the underlying degradation mechanisms and process correlations via (HT-)OEMS provides a novel and important understanding of the phenomena that give rise to thermal runaway in lithium-ion batteries. This cell chemistry-based insight can be used to guide future prevention-focused safety assessments. Figure 1

Li-Ion Cell in Operando Monitoring and Prognostication Using CMUT Devices

Capacitive micromachined ultrasonic transducer (CMUT) devices are ideal solutions for in operando battery monitoring applications especially for consumer electronics. Their minute size (2mm x 1mm x 0.5mm) allows direct placement on the battery without affecting the form factor of the device, the volume production techniques used for their manufacture allow for a very low-cost device, and they can be easily integrated with front-end integrated circuits either in a single device or in a discrete multichip form. Together with industry partners we have developed CMUT devices that we use to continuously monitor the behavior of a battery while it is cycling.For this work we used CMUTs (close-up shown in Fig. 1(a)) developed to operate with a low bias voltage (less than 30 V) which reduces the complexity of the driving hardware. The impulse response and its frequency content are shown in Fig. 1(b). In collapse mode, the peak frequency is 4.0 MHz and the one-way –3 dB BW is 76%, which allows flexibility in setting the drive conditions to interrogate the battery. Our testing also shows that the CMUTs show good device-to-device uniformity and they have a very stable performance in variable temperature environments (e.g. 0℃ - 60℃ ).The cell is interrogated in pulse-echo mode. The CMUT is excited by a wide-band unipolar pulse and the returned analog signal is filtered and amplified. The signal is then digitized and processed to extract features that allow us to quantify the state of the battery. Figure 1(c) depicts such signal features change under baseline cell cycling conditions (three cycles at a charge rate of C/4). These changes are the result of mechanical material property changes in the cell e.g., electrode stiffness and density [1] which directly affect the acoustic wave propagation inside the cell. Figure 1(d) depicts signal feature change due cell overcharge (red line). Ultrasound is especially sensitive to gas generation which occurs as the cell voltage extends beyond normal operating range [2]. Signal features provide early warning notice that cell is outside of normal operating conditions.Figure 1. a) Close-up image of CMUT device. b) CMUT impulse response and corresponding frequency content. c) Signal features (RMS and Time of Flight (ToF)) and thickness change during C/4 charge and discharge. d) Signal features during cell constant current overcharge. Cell overcharged after 4.4V (red line). Chang, W. et al. Measuring effective stiffness of Li-ion batteries via acoustic signal processing. Mater. Chem. A 8, 16624–16635 (2020).Appleberry, M. C. et al. Avoiding thermal runaway in lithium-ion batteries using ultrasound detection of early failure mechanisms. Journal of Power Sources 535, 231423 (2022). Figure 1

Numerical analysis of thermal runaway process of lithium-ion batteries considering combustion

We studied the thermal runaway process of lithium-ion batteries (LIBs) caused by thermal abuse, with a particular focus on the effects of combustion. First, we observed a gradual increase in battery temperature during thermal runaway until it reached 190 °C, at which point it sharply rose to approximately 500 °C. However, thermal runaway induced by combustion was characterized by a sudden temperature increase at lower temperatures. Second, we analyzed the internal reactions occurring in a location far from the heat source resulting from combustion. We found that the solid electrolyte interface (SEI) decomposition contributed to nearly 90 % of the heat generated at lower temperatures, while the positive electrode-electrolyte reaction emerged as the major heat source at temperatures exceeding 195 °C. Finally, we also examined the internal reactions in a location close to the heat source caused by combustion. We identified that the internal reactions initiated at around 50 °C and occurred simultaneously. The heat generated by the negative electrode-electrolyte and positive electrode-electrolyte reactions accounted for approximately 47 % and 46 % of the total heat during thermal runaway, respectively. Consequently, we concluded that combustion accelerates thermal runaway in LIBs. We expect this study to enhance the prediction of heat propagation during thermal runaway.

A smart membrane with negative thermo-responsiveness in battery electrolyte solution

The challenge of thermal runaway in lithium-ion batteries necessitates innovative solutions to enhance their safety. In this work, a negatively thermo-responsive membrane is proposed with grafting poly (N-isopropylacrylamide) onto polydopamine-modified polypropylene (PP) membrane via the Michael addition reaction. The implementation of such smart membrane is achieved based on the upper critical solution temperature (UCST) of the PNIPAM in the electrolyte solution containing 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]), ethylene carbonate/diethyl carbonate (EC/DEC), and lithium tetrafluoroborate (LiBF4). The conformational transition of the PNIPAM in the electrolyte solution is intricately influenced by the competing salting-out effect of [EMIM][BF4] and salting-in effect of LiBF4. By maintaining a constant 1.0 M LiBF4 concentration in the electrolyte solution, the UCST of the PNIPAM that is precisely adjusted according to the 45.5 wt%-50 wt% of [EMIM][BF4] in the mixed EC/DEC solution provides the gating temperature. When below the gating temperature, the PNIPAM gating polymer grafted on the PP membrane remains in a shrinkable state to let the electrolyte ions shuttle feely between the electrodes. Conversely, in the event of overheating stemming from inadvertent Li-ion battery mismanagement, the PNIPAM gating polymer becomes extensible above the gating temperatures, resulting in the closure of the separator membrane. This mechanism effectively arrests the mobility of electrolyte ions, thereby contributing to the enhanced safety and security of lithium-ion batteries. The finding in this work offers valuable insights into the design and development of smart battery membranes with enhanced safety features to advance the progress of lithium-ion battery technology.

Overview of the Thermal Runaway in Lithium-Ion Batteries with Application in Electric Vehicles: Working Principles, Early Warning, and Future Outlooks

Overview of the Thermal Runaway in Lithium-Ion Batteries with Application in Electric Vehicles: Working Principles, Early Warning, and Future Outlooks

Development of equivalent circuit model for thermal runaway in lithium-ion batteries

An integrated equivalent circuit model was developed to analyze thermal runaway in lithium-ion batteries under different conditions. The thermal runaway model was developed by adding various circuit components to a second-order resistor–capacitor circuit, whose values were obtained based on previous experimental studies. First, the characteristics of thermal runaway by electrical abuse were analyzed. When the charge rate was high, the maximum temperature during thermal runaway was high, and the thermal runaway ended fast. At charge rate of 3C, the maximum temperature was 209.4 °C, since a high current generates large heat, and the thermal runaway duration was 1200 s. Next, thermal runaway by mechanical abuse was analyzed by examining the state of charge effect on the maximum temperature. When the state of charge increased from 0.5 to 1, the temperature increased to 470 °C during thermal runaway because a high potential difference arises when the state of charge is high. Lastly, an integrated equivalent circuit model was developed by adding a series of resistors and capacitors in parallel to the conventional battery model. The model showed an accuracy of 87 % compared to previous experimental results. The proposed model can enable the analysis of thermal runaway during fast charge caused by combined abuse factors.

Research on internal short circuit detection method for lithium-ion batteries based on battery expansion characteristics

Short circuits are a major contributor to thermal runaway in lithium-ion batteries, but present detection techniques cannot distinguish different forms of short circuits. Therefore, the paper provides a detection method for internal short circuits (ISCs) based on coupled mechanical stress that can determine the type of short circuit. Firstly, cathode-anode (Ca-An) short-circuit batteries with a controllable triggering time and measurable internal temperature and electrode potential are designed. Secondly, the performance evolution of fault batteries under coupled mechanical stress conditions is investigated, along with the impact of faults on the battery's safety performance. Additionally, the influence of battery expansion characteristics on the contact pressure at the short circuit location and the correlation between short circuit resistance and mechanical stress are analyzed. The results show, except for self-discharge, no significant differences between Ca-An short-circuit and normal batteries, and there are no mutable features observed, but the faults can exacerbate internal-external temperature differences during charging. The different reasons for thermal runaway during sustained pressurization between short-circuit and normal batteries are revealed. Finally, a method for detecting ISC based on the differences in short-circuit resistance at different states of charge is proposed. Overall, the paper provides a basis for fault classification in lithium-ion batteries.

Efficiency of dodecafluoro-2-methylpentan-3-one microemulsion to inhibit thermal runaway in lithium-ion batteries

Efficiency of dodecafluoro-2-methylpentan-3-one microemulsion to inhibit thermal runaway in lithium-ion batteries

Model-free quantitative diagnosis of internal short circuit for lithium-ion battery packs under diverse operating conditions

The internal short circuit (ISC) serves as a primary source of thermal runaway in lithium-ion batteries, thereby posing a potential safety risk. The early identification of ISC faults is crucial for mitigating risks associated with fire or explosion, but quantitatively diagnosing minor energy leakage in the initial stage of ISC can be a considerable challenge in the absence of battery modeling or preliminary experiments. In light of these constraints, this study puts forth a quantitative diagnosis technique underpinned by an innovative model-free approach tailored for battery pack systems. Our method hinges on the analysis of voltage characteristics and certain premises, wherein the variance in the quantity of electrical charge retained in a cell is estimated solely through measured voltage data. The ISC current is determined through measured current data while maintaining cell balance within the packs. In addition, we propose an ISC current compensation scheme to accommodate fluctuations in ambient temperatures over time. Consequently, the ISC resistances of all cells within the packs can be computed as an index of fault to assess the degree of ISC severity. To ascertain the feasibility of our proposed method, we undertook ISC pack experiments under a wide range of conditions, encompassing aspects such as cell inconsistency, cell balancing, subzero and varying ambient temperatures, and diverse charge/discharge protocols. The results of our experiments demonstrate that the proposed model-free method exhibits considerable applicability for real-world battery operational circumstances while also maintaining a high degree of accuracy in ISC resistance estimation.

Experimental study on thermal runaway characteristic and residue of Li(Ni0.8Co0.1Mn0.1)O2 lithium-ion batteries induced by overcharge

Overcharge is one of the most common triggers of thermal runaway in lithium-ion batteries. The process and mechanism of overcharging are not clarified. In particular, little research has been done on thermal runaway residues. Accident investigators require a method to identify thermal runaway residue. In this study, the thermal runaway induced by 1C (12 A) current overcharge in 12 Ah pouch Li(Ni0.8Co0.1Mn0.1)O2 lithium-ion batteries was investigated. The battery residue was disassembled. Scanning electron microscopy, X-ray diffractometry, and other analysis methods were used to investigate macro characteristics, micromorphology, and phase composition of the residue. The analysis of the residues revealed that the layered electrode adhesion was severe, the current collectors at the rupture were damaged and ejected, and copper molten beads were observed in the ejecta. Numerous fracture and breaking were observed in the residue cathode material particles, and the explanatory hypothesis was proposed. New phase C, Li2CO3, LiF, MnO, NiO, Co and Ni were found. Also, the mechanisms of the phenomena and characteristics were discussed. Accident investigators would be helped if these overcharge characteristics were widely validated.

Monitoring and diagnostic approaches for thermal runaway in lithium-ion batteries

Monitoring and diagnostic approaches for thermal runaway in lithium-ion batteries

A Polyacrylonitrile Shutdown Film for Prevention of Thermal Runaway in Lithium-Ion Cells

The electrodeposition of a polymer (polyacrylonitrile, PAN) is used to reduce the risk of thermal runaway in lithium-ion batteries, which is the most important cause of battery accidents and fires. PAN was electrodeposited on a graphite battery electrode, using cyclic voltammetry or chronoamperometry, in a solution with acrylonitrile as the solvent. The electrodeposited PAN film was characterised by Raman spectroscopy, microscopy, energy dispersive X-ray analysis, and thermogravimetric analysis, and it was found that the film thickness could be controlled by the amount of charge passed in the electrochemical experiments. The PAN-coated graphite battery electrode was then tested in lithium half-cells, obtaining capacities close to the uncoated graphite sample (ca. 360 mA h g−1) for thin (<10 µm) polymer coatings at 25 °C. Interestingly, for thicker polymer coatings (>20 µm) it was found that the capacity decreased drastically as the temperature increased beyond 80 °C. Such suppression in capacity has applications for thermal runaway protection since the electrochemical reactions of degradation of the electrolyte in contact with the electrode are the root cause of the thermal runaway process. Further work should look into alternative polymer and liquid electrolyte formulations to achieve the desired suppression of electrochemical capacity at high temperatures while retaining high capacities at the operational temperature range.

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

Identification of Internal Short-Circuit Faults in Lithium-Ion Batteries Based on a Multi-Machine Learning Fusion

Internal short-circuit (ISC) faults are a common cause of thermal runaway in lithium-ion batteries (LIBs), which greatly endangers the safety of LIBs. Different LIBs have common features related to ISC faults. Due to the insufficient volume of acquired ISC fault data, conventional machine learning models could not effectively identify ISC faults. To compensate for the above deficiencies, this paper proposes a multi-machine learning fusion method to predict ISC faults and to perform faults warning classification under multiple operating conditions using the input of voltage normalization. Firstly, learning data acquisition is captured by experiments and simulation. Secondly, the simulation data are inputted into the ResNet-convolutional neural network (CNN) for pretraining, followed by the transfer learning method to freeze parts of the model layers in the CNN, and part of the experimental data are also inputted into the CNN model for parameter fine-tuning to build a multi-machine learning model. Finally, the degree of ISC faults within the laboratory battery is predicted based on the multi-machine learning model. The results show that the CNN model had a 99.9% prediction accuracy on the simulated dataset, and the multi-machine learning fusion model after transfer learning had a 96.67% prediction accuracy on the laboratory battery dataset, which can accurately identify different levels of ISC faults in batteries and realize the graded warning of ISC faults.

An integrated methodology for dynamic risk prediction of thermal runaway in lithium-ion batteries

The risk of thermal runaway in lithium-ion battery (LIB) attracts significant attention from domains of society, industry, and academia. However, the thermal runaway prediction in the framework of system safety requires further efforts. In this paper, we propose a methodology for dynamic risk prediction by integrating fault tree (FT), dynamic Bayesian network (DBN) and support vector regression (SVR). FT graphically describes the logic of mechanism of thermal runaway. DBN allows considering multiple states and uncertain inference for providing quantitative results of the risk evolution. SVR is subsequently utilized for predicting the risk from the DBN estimation. The proposed methodology can be applied for risk early warning of LIB thermal runaway.

Self-shutdown function based on overcharge-triggered electrochemical nano-switch for safer Li-ion batteries

Overcharge abuse is one of the most common initiators of thermal runaway in lithium ion batteries (LIBs). Much efforts have been devoted to the developments of advanced Battery Management System (BMS) and redox shuttles to provide overcharge protection for LIBs. However, the current overcharge protection strategies are not able to permanently eliminate the safety hazards caused by overcharge abuse. Herein, we propose a new overcharge protection mechanism based on the overcharge-triggered electrochemical nano-switch (denoted as OTENS). The results demonstrate that the insertion of OTENS into between the current collector and the active mass has a little negative effect on the electrochemical performances of battery under normal and slight overcharge conditions. More importantly,the OTENS will be activated under deep overcharge condition, permanently shutting down the overcharged cell and consequently avoiding the continuous cell damage. Such a overcharge-triggered shutdown mechanism originates from the overoxidation of electrically conductive polymer that causes the loss of its electrochemical activity and electric conduction. This electrode design for constructing safer LIBs is simple and also fully compatible with the present industrial manufacture process.

Numerical modeling of thermal runaway in high-energy lithium-ion battery packs induced by multipoint heating

Thermal runaway in lithium-ion batteries is a primary safety concern in electric vehicles (EVs). Herein, a numerical thermal abuse model is proposed that integrates ordinary differential equations (ODEs), heat-transfer partial differential equations (PDEs), natural convection in computational fluid dynamics (CFD), and thermal radiation to investigate thermal propagation in a battery pack. A three-dimensional geometric model of a high-energy lithium-ion battery pack comprising 18,650 format cells was constructed to analyze the thermal characteristics using the finite element method (FEM). A thermal abuse test was conducted to simulate the spread of thermal runaway in cells owing to multipoint heating. The maximum differences in the peak temperature between the proposed model and the model without convection were −150 K and 52.0 s, respectively, while the differences between the proposed model and the model without radiation were −52.4 K and −125.0 s, respectively. Furthermore, four additional models with different cell-to-cell gaps were constructed to study the thermal propagation characteristics, showing that the presence of a cell-to-cell gap accelerated heat transfer but compromised energy density for the battery pack. Ultimately, the coupling model at the pack level proposed in this study can improve the design of battery thermal management systems.