Thermal Runaway Of Lithium-ion Batteries Research Articles

A comparative study on multidimensional signal evolution during thermal runaway of lithium-ion batteries with various cathode materials

Cathode materials significantly affect the failure behavior of lithium-ion batteries, but there is a lack of comparative research on the multidimensional signal evolution for batteries with various cathode materials when subjected to thermal runaway (TR). This study investigates the effect of cathode materials on battery safety properties by conducting overheating and overcharging abuse experiments on LiNixCoyMn(1-x-y)O2 (NCM 523, 622, and 811) as well as LiFePO4 (LFP) batteries. The multidimensional signals, including expansion force, gas concentrations, temperature, and voltage, are comprehensively and quantitatively analyzed. The results demonstrate that expansion force shows the earliest anomalies regardless of the cathode material in both abuse conditions. Gas can be detected after venting, followed by significant anomalies in voltage and temperature. Additionally, under overheating conditions, LFP cells exhibit the longest TR warning time of 677 s. However, the force anomaly-based warning method is more suitable for low-nickel NCM cells under overcharging scenarios. Specifically, NCM 523 cells achieve an overcharging warning time of 992 s at temperatures as low as 42.9 °C, and hold the highest venting force of 9859 N and venting temperature at 114.1 °C. On this basis, a hierarchical warning strategy based on multidimensional signal fusion is proposed. This study provides valuable insights into TR early warning and safety management in LIBs with different cathode materials.

Early warning for thermal runaway in lithium-ion batteries during various charging rates: Insights from expansion force analysis

Thermal runaway introduces a significant challenge in the widespread application of lithium-ion batteries, necessitating advanced early-warning technologies to ensure safety, particularly during charging. Only monitoring the temperature and voltage limit the performance of diagnostic algorithms. The expansion behavior of batteries, which is linked to their operating status, offers a vital indicator of safety. In this study, the evolution of multidimensional signals during overcharging experiments at different current rates is comprehensively investigated. The result shows that the abnormal expansion force can be detected at temperatures as low as 35.4 °C, which achieves an early warning signal 11 min earlier than the onset of battery thermal runaway. The effect of charging rate on battery safety is comprehensively analyzed, showing that the time interval between the warning signal of the expansion force and temperature increases steadily from 151 s to 682 s as the charging rate decreases. However, the charging rate hardly affects the stage of charge boundary of venting, which is around ±118 %. These insights are crucial for understanding early warning mechanisms in overcharged batteries, offering valuable guidance for enhancing the safety of electric vehicles and energy storage systems.

An Electrode-Crosstalk-Suppressing Smart Polymer Electrolyte for High Safety Lithium-Ion Batteries.

Electrode crosstalk between anode and cathode at elevated temperatures is identified as a real culprit triggering the thermal runaway of lithium-ion batteries. Herein, to address this challenge, a novel smart polymer electrolyte is prepared through in situ polymerization of methyl methacrylate and acrylic anhydride monomers within a succinonitrile-based dual-anion deep eutectic solvent. Owing to the abundant active unsaturated double bonds on the as-obtained polymer matrix end, this smart polymer electrolyte can spontaneously form a dense crosslinked polymer network under elevated temperatures, effectively slowing down the crosstalk diffusion kinetics of lithium ions and active gases. Impressively, LiCoO2/graphite pouch cells employing this smart polymer electrolyte demonstrate no thermal runaway even at the temperature up to 250°C via accelerating rate calorimeter testing. Meanwhile, because of its abundance of functional motifs, this smart polymer electrolyte can facilitate the formation of stable and thermally robust electrode/electrolyte interface on both electrodes, ensuring the long cycle life and high safety of LIBs. In specific, this smart polymer electrolyte endows 1.1AhLiCoO2/graphite pouch cell with a capacity retention of 96% after 398 cycles at 0.2 C.

Experimental analysis and safety assessment of thermal runaway behavior in lithium iron phosphate batteries under mechanical abuse

Mechanical abuse can lead to internal short circuits and thermal runaway in lithium-ion batteries, causing severe harm. Therefore, this paper systematically investigates the thermal runaway behavior and safety assessment of lithium iron phosphate (LFP) batteries under mechanical abuse through experimental research. Mechanical abuse experiments are conducted under different conditions and battery state of charge (SOC), capturing force, voltage, and temperature responses during failure. Subsequently, characteristic parameters of thermal runaway behavior are extracted. Further, mechanical abuse conditions are quantified, and the relationship between experimental conditions and battery characteristic parameters is analyzed. Finally, regression models for battery safety boundaries and the degree of thermal runaway risk are established. The research results indicate that the extracted characteristic parameters effectively reflect internal short circuit (ISC) and thermal runaway behaviors, and the regression models provide a robust description of the battery's safety boundaries and thermal runaway risk degree. This work sheds light on understanding thermal runaway behavior and safety assessment methods for lithium-ion cells under mechanical abuse.

Restoring the gas diffusion field before the fire of the LiNi0.7Co0.2Mn0.1O2 lithium-ion battery thermal runaway

Although ternary lithium-ion batteries promise high energy density, their safety issues have aroused widespread social concern. The thermal runaway phenomenon of ternary lithium-ion batteries presents a violent fire or explosion induced by the sparks. However, the reason for the disaster of thermal runaway remains unclear. This study restores gas diffusion before a fire or explosion using computational fluid dynamics(CFD) in order to explain the germination of the disaster. The calculation results revealed that the diffusion field cane divided into three zones:(1) fuel-surplus zone; (2) fuel‑oxygen zone; (3) oxygen surplus zone. The combustible zone (fuel‑oxygen zone) quickly enlarges after the safety valve is opened and is located on the top of the safety valve, so the deflagration tended to happen on the top of the safety valve a few seconds after the safety valve opened. Besides, the study also established the relationship between venting parameters and time based on the Sigmoid function. The established relationship function could provide boundary conditions for the fire dynamics of lithium-ion battery thermal runaway. Overall, the method could not only be used to further explore the combustion mechanism of lithium-ion thermal runaway, but also provided insight into the safety design of the battery pack structures.

Simulation of Dispersion and Explosion Characteristics of LiFePO4 Lithium-Ion Battery Thermal Runaway Gases.

In recent years, as the installed scale of battery energy storage systems (BESS) continues to expand, energy storage system safety incidents have been a fast-growing trend, sparking widespread concern from all walks of life. During the thermal runaway (TR) process of lithium-ion batteries, a large amount of combustible gas is released. In this paper, the 105 Ah lithium iron phosphate battery TR test was conducted, and the flammable gas components released from the battery TR were detected. The simulation tests of the diffusion and explosion characteristics of lithium iron phosphate battery's (LFP) TR gases with different numbers and positions in the BESS were carried out using FLACS simulation software. It was found that the more batteries TR simultaneously, the shorter the time for the combustible gas concentration in the energy storage cabin to reach the explosion limit. When 48 batteries were in TR simultaneously in the energy storage cabin, the shortest time was 9.8 s, and the further the location of the fire is from the hatch, the largest explosion overpressure is generated to the hatch, up to 583 kPa. When the gas generated by the TR of 48 batteries explodes, the maximum explosion overpressure at 5 m outside the energy storage cabin hatch is more significant than 40 kPa, which will cause serious injury to humans. The causes of TR of batteries in prefabricated chambers are complex, and the location and amount of thermal runaway of batteries as well as the diffusion of combustible fumes can have different effects on the external environment. The research results can provide support for the safety design of BESS.

Laser-induced thermal runaway dynamics of cylindrical lithium-ion battery

Laser is a precise, remote, and non-invasive heating method that can initiate thermal runaway of lithium-ion batteries in safety tests. This study systemically explores the thermal runaway of cylindrical cells induced by constant laser irradiation up to 20 W and 1.6 MW m−2 within a 4-mm diameter spot. Results indicate that thermal runaway intensity is relatively insensitive to the laser power but controlled by the battery state of charge (SOC). The overall heating efficiency of the laser (78 ± 7 %) is higher than that of the oven and comparable to contact heating methods. As the battery SOC decreases from 100 % to 30 %, the minimum laser output power for thermal runaway increases from 9.5 W to 15 W, corresponding to the effective battery heating power rising from 6.7 W to 11.1 W. These critical values hold significance in evaluating the thermal hazards associated with localized hotspot failures. Finally, the strategy for applying the laser to trigger the battery thermal runaway is proposed based on a simplified heat transfer model. This work reveals the battery fire risk under high-intensity spot heating and provides a valuable scientific basis for using laser heating in battery safety test standards.

Causes and mechanism of thermal runaway in lithium-ion batteries, contradictions in the generally accepted mechanism

In this paper, experimental results are analyzed that contradict the generally accepted scheme of thermal runaway reactions. Also, it was experimentally proved that three main exothermic reactions determine the thermal runaway process of lithium-ion batteries. The first main exothermic reaction of the thermal runaway is the reaction releasing the electrochemical energy accumulated in the lithium-ion batteries during their charging. The second main exothermic reaction of the thermal runaway is the reaction of lithiation of surface layers of a cathode active material; this reaction is performed by the lithium atoms coming from both the anode and the inner layers of the cathode active material. The third main exothermic reaction of the thermal runaway is the reaction of the cathode metal-oxides decomposition and the electrolyte oxidation by the released oxygen. Besides, it is shown here that the open circuit voltage drop in batteries during the thermal runaway is mainly due to the lithiation of the cathode active material and – to a much lesser extent – to short circuits occurrence of the electrodes. The established mechanism of thermal runaway of lithium-ion batteries makes it possible to quantitatively describe all currently known experimental results.

Modeling the propagation of internal thermal runaway in lithium-ion battery

The trend toward high capacity and huge size in lithium-ion batteries has made it necessary to investigate the internal thermal characteristics. In this study, a thermal runaway model was developed to describe lithium-ion batteries' internal thermal characteristics. Moreover, triggering energy was proposed as a critical feature for evaluating and characterizing the thermal runaway under diverse thermal abuse situations, with large differences among characteristic temperatures. Finally, the effects of battery configuration on thermal runaway behaviors were investigated. The modeling results showed that internal temperature distribution can be divided into four characteristic stages with two jelly rolls, and the application of more numerous and thinner cells inside a battery can accelerate the propagation of thermal runaway. The experimental results showed that the ratio of triggering energy of self-heat onset to total self-heat generation remained consistent in an adiabatic environment. The mean value of the ratio was 24.5%, indicating that lithium iron phosphate batteries obtain most of the energy (generally 80%) from internal exothermic reactions during adiabatic thermal abuse. The triggering energy of thermal runaway remained constant when various heating powers were applied to one of the batteries' laterals (about 20.8% of theoretical energy contained inside lithium iron phosphate batteries). Triggering energy can provide new insights into the modeling of thermal runaway mechanisms and propagation.

Laminar burning velocity of lithium-ion battery thermal runaway vent gas in air

In this study, a spherically propagating flame of vent gas generated during the thermal runaway of lithium-ion batteries with different states of charge (SOC) was experimentally and numerically investigated. The vent gas is mainly composed of H2, CO, CO2, and some hydrocarbons. With increasing SOC, the CO2 fraction tends to decrease while the H2 and CO fractions tend to increase. Combustion experiments were conducted using a closed vessel, and the combustion progression was captured using a high-speed Schlieren image system to measure the unstretched laminar burning velocity, Su0. In addition, the combustion was computationally estimated under the experimental conditions by performing 1D planar flame simulations using Chemkin-Pro with the Aramco Mech 1.3 reaction model. Remarkably, the calculated values of Su0 closely matched the experimental ones, demonstrating good agreement. The results showed that Su0 tended to increase with increasing SOC. Furthermore, the effects of the chemical reaction mechanism, which plays a pivotal role in driving this increase in Su0 with increasing SOC, were investigated. Specifically, the heightened SOC levels promoted the H2 branching reaction led to an increased concentration of OH radicals in the mixture. This consequently accelerated the rate-determining reaction for the oxidation of hydrocarbons, leading to an increase in Su0. As an effect of the hydrocarbons in the vent gas mixtures, the number of moles of CO increased slightly near the flame because the rate of CO production in the flame zone was more dominant than that of consumption under the condition of SOC 50.

In situ and Real‐time Monitoring the Chemical and Thermal Evolution of Lithium‐ion Batteries with Single‐crystalline Ni‐rich Layered Oxide Cathode

AbstractHigh‐capacity Ni‐rich layered oxides are promising cathode materials for fabrication of lithium‐ion batteries (LIBs) with high energy density. However, thermal runaway of LIBs with these cathodes leads to great safety concerns. In this study, single crystalline LiNi0.9Co0.05Mn0.05O2 (NCM‐SC) has been prepared and a flexible optical fiber was buried inside the pouch‐type LIBs with NCM‐SC cathode to in situ study its real‐time temperature evolution during charge/discharge process. NCM‐SC exhibits an enhanced Li+ ions transportation efficiency and electrode reaction kinetics, which can effectively reduce the generation of polarization heat and mitigate the internal temperature rise of the pouch‐type battery. Meanwhile, solid‐electrolyte interface (SEI) film decomposition and gas accumulation are effectively alleviated, due to the enhanced thermal stability of SEI film formed on NCM‐SC. Moreover, the single crystal architecture can effectively retard layered to spinal and rock‐salt phase transition, mitigate the crack formation and structural collapse. Consequently, NCM‐SC exhibits an excellent electrochemical performance and enhanced thermal stability.

In situ and Real-time Monitoring the Chemical and Thermal Evolution of Lithium-ion Batteries with Single-crystalline Ni-rich Layered Oxide Cathode.

High-capacity Ni-rich layered oxides are promising cathode materials for fabrication of lithium-ion batteries (LIBs) with high energy density. However, thermal runaway of LIBs with these cathodes leads to great safety concerns. In this study, single crystalline LiNi0.9Co0.05Mn0.05O2 (NCM-SC) has been prepared and a flexible optical fiber was buried inside the pouch-type LIBs with NCM-SC cathode to in situ study its real-time temperature evolution during charge/discharge process. NCM-SC exhibits an enhanced Li+ ions transportation efficiency and electrode reaction kinetics, which can effectively reduce the generation of polarization heat and mitigate the internal temperature rise of the pouch-type battery. Meanwhile, solid-electrolyte interface (SEI) film decomposition and gas accumulation are effectively alleviated, due to the enhanced thermal stability of SEI film formed on NCM-SC. Moreover, the single crystal architecture can effectively retard layered to spinal and rock-salt phase transition, mitigate the crack formation and structural collapse. Consequently, NCM-SC exhibits an excellent electrochemical performance and enhanced thermal stability.

Mechanism and Protective Measures of Thermal Runaway in Lithium-ion Batteries

Mechanism and Protective Measures of Thermal Runaway in Lithium-ion Batteries

Experimental and Modeling Analysis of Thermal Runaway for LiNi0.5Mn0.3Co0.2O2/Graphite Pouch Cell Triggered by Surface Heating

With the rapid advancement of battery technology, the energy density and power density of lithium-ion batteries (LIBs) as a key component of electric vehicles have been increasing. However, accidents triggered by the thermal runaway of LIBs have been occurring frequently. Therefore, to address this issue, it is imperative to investigate the TR characteristics of the battery under various conditions. This study investigates the TR characteristics of ternary pouch LIBs induced by surface heating, using techniques such as voltage and temperature acquisition, as well as video imaging. The experimental results are analyzed to elucidate the venting and combustion characteristics of the cells. Furthermore, in order to provide a more comprehensive elucidation of the TR behavior of the battery, a corresponding 3D model for surface-induced TR was constructed. The simulation results of this model are in good agreement with the experimental results and effectively capture the TR characteristics of the cells under surface heating. Finally, the simulation results showed that the cells are more prone to venting from the side due to the lower melting point of the polypropylene (PP) adhesive used for cell sealing. The use of high-temperature-resistant sealing adhesives is crucial in preventing uncontrolled lateral venting of the cells.

Metal (Ni, Pd, and Pt)-Doped BS Monolayers as a Gas Sensor upon Vented Gases in Lithium-Ion Batteries: A First-Principles Study.

Real-time monitoring of the vented gases emitted by the thermal runaway of lithium-ion batteries (LIBs) is of great significance to the normal use of LIBs. We study systematically the adsorption and sensing performances of pristine and metal-doped BS monolayers to five typical gases (CO, CO2, CH4, C2H2, and C2H4) emitted from LIBs employing the first-principles method. The adsorption structure and energetics, charge transfer, band structure, density of states, sensitivity, and recovery time are simulated and analyzed. Outstanding sensing properties are predicted for the Ni-, Pd-, and Pt-doped BS monolayers, although their recently synthesized pristine counterpart shows little sensing potential for those gases. The magnitude of the adsorption energy increases from 0.249 eV to 2.32 eV (Ni-BS), 1.954 eV(Pd-BS), and 2.994 eV (Pt-BS) for the CO gas after doping. Besides, significant variation of band gap is observed after gas adsorption in doped BS nanosheets, which leads to huge theoretical values of the sensitivity. The sensitivity for CO, CO2, CH4, C2H2, and C2H4 on Pt-BS may reach up to 5.87 × 105, 1.57 × 106, 1.81 × 105, 8.33 × 104, and 8.18 × 103, respectively. In addition, the calculated recovery times indicate that the doped BS monolayers have strong selectivity for the adsorption and detection of these five gases. The three metal-doped BS monolayers should have great potential for application in sensors monitoring the gases emitted from LIBs.

A Review of Thermal Runaway Prevention and Mitigation Strategies for Lithium-ion Batteries

Lithium-ion batteries are widely considered the leading candidate energy source for powering electric vehicles due to their high energy and power densities. The thermal runaway of lithium-ion batteries is the phenomenon of chain exothermic reactions within the battery. These reactions cause a sharp rise in the internal battery temperature causing the inner structures of the battery to destabilize and degrade, which eventually leads to the failure of the battery. This study thermal runaway initiation mechanisms, thermal runaway propagation, Thermal runaway is a major safety concern; therefore, the development of mathematical and numerical experimental models to predict thermal runaway is reviewed, which provides useful data to design and develop battery packs with thermal runaway safety features.It explores the importance of effective battery thermal management systems to prevent thermal runaway and reviews strategies for mitigating damages in case of an occurrence.

A comparative investigation of charging conditions on thermal runaway of lithium-ion batteries induced by different incident heat fluxes

Thermal runaway poses a great challenge for lithium-ion battery applications, an in-depth delve into the thermal characteristics and fire behaviors is paramount to battery thermal management system design and fire prevention. This work intends to investigated the thermal characteristics and fire behaviors of batteries when subjected to different charging rates and without charging treatment under different incident heat fluxes by using of a cone calorimeter. Experimental results indicate that the battery thermal risk increased with increasing charging rate, manifesting lower internal short circuit and onset temperature, as well as higher maximum temperature and heat release rate. It was observed that the flame extension length rose from 32.85 mm at 0.5 C to 68.85 mm at 3 C during the venting stage. In addition, the charging time terminated prematurely which led to the final SOC declined by 5.2%−22%. Thermal runaway onset time reduced by between 746 s and 962 s as the incident heat flux increased from 20 kW/m2 to 50 kW/m2. Furthermore, the increasing thermal runaway duration without charging treatment, suggesting the accelerating effect of charging current. Subsequently, a semiempirical ignition model was developed. This work aims to give a comprehensive understanding of thermal runaway characteristics in the presence of dual charging and heat flux conditions and hopes to provide meritorious references for the safety of lithium-ion battery applications.

Quantitative diagnosis of micro-short circuit for lithium-ion batteries considering aging based on incremental capacity curve

Early diagnosis of internal short-circuit faults for preventing thermal runaway in lithium-ion batteries stands as a pivotal task within battery management systems. With the continuous use of electric vehicles, the coexistence of aging and micro-short circuit (MSC) within battery packs is possible. These two faults manifest identical characteristics during discharge, rendering them susceptible to erroneous diagnoses. In this study, a novel fault diagnosis method based on the incremental capacity (IC) curves is proposed, devised to discern aging cells from those afflicted by MSC. This method screens out aging cells by feature parameters of IC curve. Based on the unique correspondence between IC peak and state of charge in this study, the cell that reaches the peak first is designated as the reference cell. By calculating the leakage current based on the temporal divergence of peak arrivals of each cell from this reference, this method estimates the MSC resistance to quantify the degree of the short-circuit fault. A series of experiments involving the presence of aging batteries, simultaneous occurrence of multiple MSC faults, or the evolution of MSC severity indicate the method is feasible and effective for diagnosing aging and MSC faults in battery packs simultaneously.

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.