This study shows that sulfide solid-state electrolytes,β-Li_(3)PS_(4)and Li_(6)PS_(5)Cl,are flammable solids.Both solid-state electrolytes release sulfur vapor in a dry,oxidizing environment at elevated temperature&l...This study shows that sulfide solid-state electrolytes,β-Li_(3)PS_(4)and Li_(6)PS_(5)Cl,are flammable solids.Both solid-state electrolytes release sulfur vapor in a dry,oxidizing environment at elevated temperature<300℃.Sulfur vapor is a highly flammable gas,which then auto-ignites to produce a flame.This behavior suggests that an O_(2)-S gas-gas reaction mechanism may contribute to all-solid-state battery thermal runaway.To improve all-solid-state battery safety,current work focuses on eliminating the O_(2)source by changing the cathode active material.The conclusion of this study suggests that all-solidstate battery safety can also be realized by the development of solid-state electrolytes with less susceptibility to sulfur volatilization.展开更多
This study focuses on the thermal management of 4680-type cylindrical lithium-ion battery packs utilizing NCM811 chemistry.It establishes coupled multi-physics models for both immersion and serpentine cold plate cooli...This study focuses on the thermal management of 4680-type cylindrical lithium-ion battery packs utilizing NCM811 chemistry.It establishes coupled multi-physics models for both immersion and serpentine cold plate cooling systems.Through a combination of numerical simulation and experimental validation,the technical advantages and mechanisms of immersion cooling are systematically explored.Simulation results indicate that under a 3C fast-charging condition(inlet temperature 20℃,flow rate 36 L/min),the immersion cooling structure 3demonstrates a triple enhancement in thermal performance compared to the cold plate structure 1:a 13.06%reduction in peak temperature,a 31.67%decrease in overall maximum temperature difference,and a 47.62%decrease in single-cell temperature deviation,while also reducing flow resistance by 33.61%.Furthermore,based on the immersion cooling model,a small battery module comprising seven cylindrical cells was designed for thermal runaway testing via nail penetration.The results show that the peak temperature of the triggered cell was limited to 437.6℃,with a controllable temperature rise gradient of only 3.35℃/s and a rapid cooling rate of 0.6℃/s.The maximum temperature rise of adjacent cells was just 64.8℃,effectively inhibiting thermal propagation.Post-test disassembly revealed that the non-triggered cells retained>99.2%of their original voltage and>99%structural integrity,confirming the module’s ability to achieve“localized failure with global stability.”展开更多
Anode binders undergo decomposition during thermal runaway,generating highly flammable and explosive hydrogen,which poses a significant threat to the safety of lithium-ion batteries.However,the binder due to its relat...Anode binders undergo decomposition during thermal runaway,generating highly flammable and explosive hydrogen,which poses a significant threat to the safety of lithium-ion batteries.However,the binder due to its relatively small proportion is often overlooked in terms of its importance.This study elucidates the universal mechanism of hydrogen generation from the decomposition of binders and identifies the hydrogen-containing chemical bonds within the molecular structure of binders as the fundamental sources of hydrogen.The Fourier transform infrared spectroscopy of six commonly used binders reveals that five of them possess hydrogen-containing chemical bonds,indicating a potential for hydrogen generation,whereas the polytetrafluoroethylene binder lacks such bonds and cannot generate hydrogen.Differential scanning calorimetry is employed to compare the decomposition of these binders and their reaction with lithiated graphite.The results demonstrate that cyclic molecular structures not only enhance thermal stability but also increase the difficulty of hydrogen generation.Moreover,binders devoid of hydrogen atoms exhibit superior thermal stability and completely eliminate the risk of hydrogen generation.These findings provide critical insights into the molecular design of binders,offering promising strategies to mitigate or prevent hydrogen generation from binder decomposition and thereby substantially improve the safety of lithium-ion batteries.展开更多
This study investigates the influence of runaway current in runaway plasmas on the dynamics of sawtooth oscillations and resultant loss of runaway electrons(RE)using the 3D magnetohydrodynamic(MHD)code M3D-C^(1)(Jardi...This study investigates the influence of runaway current in runaway plasmas on the dynamics of sawtooth oscillations and resultant loss of runaway electrons(RE)using the 3D magnetohydrodynamic(MHD)code M3D-C^(1)(Jardin et al 2012 J.Comput.Sci.Discovery 6014002).Using an HL-2A-like equilibrium,we confirm that in the linear phase,the impact of REs on resistive internal kink instabilities is consistent with previous research.In the nonlinear phase,as the runaway current fully replaces the plasmas current,we observe a significant suppression of sawtooth oscillations,with the first sawtooth cycle occurring earlier compared to the case without runaway current.Following the first sawtooth collapse,plasma current density,runaway current density,and safety factor(q)flatten within the q=1 surface,albeit displaying fine structures.Subsequently,the growing high torodial(n)and poloidal(m)mode number modes disrupt the magnetic surfaces,leading to the loss of REs outside the q=1 surface,while minimally affecting the majority of REs well-confined within it.Thus,in the current model,the physical processes associated with the presence of sawtooth oscillations do not effectively dissipate runaway current,as REs are assumed to be collisionless.In addition,the final profile of runaway current density exhibits increased steepening near the q=1 surface in contrast to the initial profile,displaying a distinctive corrugated inhomogeneity influenced by the growing fluctuation of the n=0 component.Finally,detailed convergence tests are conducted to validate the numerical simulations.展开更多
As lithium-ion batteries(LIBs)continue to evolve toward lower costs and higher energy densities,their potential safety risks have become increasingly apparent.Incidents such as explosions at energy storage facilities,...As lithium-ion batteries(LIBs)continue to evolve toward lower costs and higher energy densities,their potential safety risks have become increasingly apparent.Incidents such as explosions at energy storage facilities,fires in electric vehicles,and building fires ignited by charging two-wheeled vehicles have been occurring with alarming frequency,often resulting in significant casualties and injuries.Conducting indepth investigations into thermal runaway(TR)incidents in LIBs can significantly reduce the risk of future occurrences.However,current investigations into LIB fire and explosion incidents face challenges due to the difficulty of conducting in-depth analyses and the lack of a robust theoretical framework to guide these investigations.To enhance the effectiveness of in-depth investigations into battery fire and explosion incidents and to address the lack of theoretical guidance,this paper is the first to systematically examine the conservation and flow patterns of elements during the TR process of LIBs.The analysis reveals that during TR,the gas products generated include approximately 1.5 g of H_(2),23.6 g of CO,88.4 g of CO_(2),8.9 g of C_(2)H_(4),7.3 g of CH_(4),3.7 g of C_(2)H_(6),and 82 g of electrolyte vapor.After TR,the solid compounds formed consist of approximately 2.5 g of LiF,29–92.2 g of elemental Ni/Co/Mn,11.4 g of Li_(2)CO_(3),200.6 g of graphite,1.4 g of NiO,29.6 g of MnO,30.1 g of CoO,67 g of elemental Cu,0.03 g of LiNiO_(2),and 4.3 g of LiAlO_(2).Importantly,the energy released from reactions forming solid compounds during TR surpasses that from gas-forming reactions.This investigation represents the first application of Hess’s law to verify the conservation of elements during the TR process of lithium-ion batteries.The proposed methodology is also applicable to other types of energy storage batteries,effectively advancing techniques for comprehensively investigating lithium battery fire and explosion incidents.展开更多
Thermal runaway(TR)in lithium-ion batteries(LIBs)poses significant safety risks due to its potential to trigger fires and explosions.Early warning of battery TR through gas sensing has emerged as a promising strategy ...Thermal runaway(TR)in lithium-ion batteries(LIBs)poses significant safety risks due to its potential to trigger fires and explosions.Early warning of battery TR through gas sensing has emerged as a promising strategy for hazard mitigation.However,comprehensive reviews critically summarizing recent progress in advanced gas sensing technologies remain scarce.To fill this void,we present a critical review consolidating state-of-the-art advancements in gas sensing for TR early warning.This review first overviews the fundamentals of gas sensing for TR monitoring,encompassing thermodynamics and kinetic principles of gas evolution alongside current gas sensing technologies.We then comprehensively explored multi-scale engineering methods,spanning material innovations,device configurations,and system-level integration,with an emphasis on cutting-edge techniques like additive manufacturing and data-driven design frameworks.Future research priorities are identified,including the enhancement of gas selectivity and environmental robustness,the development of machine learning-driven intelligent gas sensing networks,and the establishment of standardized protocols for practical deployment.By integrating interdisciplinary insights derived from materials science,electrochemistry,and embedded systems engineering,this review is positioned to offer actionable guidelines for advancing scalable and reliable gas-sensing solutions toward boosted LIB safety.展开更多
Sodium-ion batteries have gradually been commercialized due to their wide range of material sources and low cost.However,there are few studies focusing on the commercial sodium-ion battery safety,especially the relati...Sodium-ion batteries have gradually been commercialized due to their wide range of material sources and low cost.However,there are few studies focusing on the commercial sodium-ion battery safety,especially the relationship between heat and gas generation is unclear.This work conducts the thermal runaway(TR)experiments of commercial 18650 sodium-ion batteries with different states of charge(SOCs)under adiabatic accelerated rate calorimetry and localized overheating.The results show that heat generation values of 50% and 100%SOC batteries during TR are 175.2 and 328.2 J g^(-1),respectively.Whereas,0%SOC batteries do not trigger TR.Moreover,the reaction sources and pathways of gas generation during TR are critically sorted out.Finally,two important conclusions are obtained.(i)During the five stages of TR,the heat generation from the safe venting to the triggering of TR stage is the highest in 50%SOC batteries,accounting for 62.5% of the total heat generation.However,for 100%SOC batteries,the heat generation from triggering TR to maximum temperature stage has the largest proportion during TR,at 57%.The 50%SOC batteries present characteristic of slow heat generation,while the 100%SOC batteries show characteristics of accelerated heat generation.(ii)Based on dimensionless analysis,the heat/gas generation ratios of 50% and 100%SOC batteries are 0.262 and 0.028,respectively.The gas generation behavior occur earlier than heat generation behavior during the whole process of TR of sodium-ion batteries.This study provides a direction for the development of high-safety sodium-ion batteries and thermal runaway suppression technology.展开更多
Cascading thermal runaway(TR)propagation poses a critical safety concern for large-format sodium-ion battery(SIB)systems because of the heightened risks of fires or explosions.However,effectively suppressing TR propag...Cascading thermal runaway(TR)propagation poses a critical safety concern for large-format sodium-ion battery(SIB)systems because of the heightened risks of fires or explosions.However,effectively suppressing TR propagation without introducing unintended side effects remains a significant challenge.Herein,we demonstrate a localized energy release method to mitigate TR,by reducing the state of charge(SOC)of cells adjacent to the thermally runaway unit.We discover that as the SOCs decreased from 100%to 25%,the TR trigger temperature decreased significantly,and the maximum temperature decrease from 367 to 229℃.Meanwhile,the volume of gas decreased to one-third of its original value,while the range of explosion limits significantly narrowed.The analysis of the morphology of the debris further confirms that the structural damage is greater at higher SOC levels.Moreover,an Entropy Weight and Technique for Order Preference by Similarity to an Ideal Solution(EW-TOPSIS)method has been established to assess the safety status of SIBs,showing that the TR possibility is nearly linear with the SOCs,and the TR hazard is exponentially related to the SOCs.Finally,when the SOC of cells adjacent to the TR cell is reduced to 25%,TR can be directly blocked without the need for additional cooling or thermal insulation methods.This study not only advances the understanding of TR behavior in SIBs but also offers a straightforward approach to mitigating the TR risk in SIB systems.展开更多
Thermal runaway(TR)in lithium-ion batteries(LIBs)involves a complicated multiphysics process with potentially catastrophic consequences,highlighting the importance of investigating effective prevention strategies.This...Thermal runaway(TR)in lithium-ion batteries(LIBs)involves a complicated multiphysics process with potentially catastrophic consequences,highlighting the importance of investigating effective prevention strategies.This study employs a lumped model integrating electrochemical and decomposition reaction kinetics to predict the evolution of the TR of LIBs triggered by axial nail penetration,validated by experimental tests.A computational fluid dynamics(CFD)-based turbulent flow model is further employed to simulate the thermal runaway propagation(TRP)behavior induced by high-temperature gases within the battery module.A parameterized analysis based on numerical simulation is conducted to quantify the impact of thermal insulation material properties on thermal diffusion and heat accumulation within the module.The results indicate that damage to the battery vent significantly increases the risk of sidewall rupture during TR.The incorporation of thermal barriers is essential in the thermal design of battery modules to prevent heat transfer via convection from the thermal exhaust caused by sidewall rupture to adjacent cells.In addition,a reduction in the thermal diffusivity of the thermal barrier material is required to minimize thermal exchange between battery cells.By adopting insulating materials with thermal diffusivity lower than 0.3 mm^(2)/s,the TRP of batteries can be mitigated under non-enclosed conditions.These findings contribute to improved battery safety and inform the development of more effective thermal protection measures and safety standards.展开更多
In this work,a series of experiments are carried out to investigate the effect of charge/discharge rates(1,2,3 and 4 C)and state of charges(SOCs,namely 0%,50%,75%and 100%)on thermal runaway(TR)and fire behavior of lit...In this work,a series of experiments are carried out to investigate the effect of charge/discharge rates(1,2,3 and 4 C)and state of charges(SOCs,namely 0%,50%,75%and 100%)on thermal runaway(TR)and fire behavior of lithium iron phosphate(LFP)batteries.The TR process caused by overheating LFP batteries is usually divided into four stages,with high temperatures and fire risks.High-rate charge and discharge damage the internal morphology and structural stability of materials seriously.The TR behavior of battery is fully aggravated,which is further manifested by the advanced opening of the safety vent,release of gas and occurrence of TR.With the increase of charging rate,the deteriorated TR characteristics can be discerned,such as the lower TR temperature,the shorter TR time,and the more serious TR consequences.Such changes can be assigned to the decline of battery stability.In addition,the battery SOC greatly impacts safety,especially the flame temperature and the severity of consequences.As for the 100%SOC battery cycled at 4 C,there is still a high risk of thermal runaway propagation at the position 1 m far away from the battery.This work helps to realize the TR and fire features of battery in-depth,enlightening the safety protection of battery.展开更多
A large number of runaway electrons(REs)generated during disruption can cause significant damage to next-generation large-scale tokamaks.The influence of three-dimensional(3D)helical magnetic perturbations on the supp...A large number of runaway electrons(REs)generated during disruption can cause significant damage to next-generation large-scale tokamaks.The influence of three-dimensional(3D)helical magnetic perturbations on the suppression of RE generation was explored using a set of 3D helical coils in J-TEXT tokamak,which can excite m/n=-2/2 helical magnetic perturbations.Experimental evidence shows that the-2/2 magnetic perturbations caused by the opposite coil current direct plasma toward the high-field side,simultaneously enhancing the magnetic fluctuations,which would enhance the radial loss of REs and even prevent RE generation.On the other hand,-2/2 magnetic perturbations can also reduce the cooling time during the disruption phase and generate a population of high-energy REs,which can interact with high-frequency magnetic fluctuations and in turn suppress RE generation.The critical helical coil current was found to correlate with electron density,requiring higher coil currents at higher densities.According to the statistical analysis of RE generation at different electron densities,the applied-2/2 magnetic perturbations can increase the magnetic fluctuations to the same level at lower electron densities,which can decrease the threshold electron density for RE suppression.This will be beneficial for RE mitigation in future large tokamak devices.展开更多
Blade batteries are extensively used in electric vehicles,but unavoidable thermal runaway is an inherent threat to their safe use.This study experimentally investigated the mechanism underlying thermal runaway propaga...Blade batteries are extensively used in electric vehicles,but unavoidable thermal runaway is an inherent threat to their safe use.This study experimentally investigated the mechanism underlying thermal runaway propagation within a blade battery by using a nail to trigger thermal runaway and thermocouples to track its propagation inside a cell.The results showed that the internal thermal runaway could propagate for up to 272 s,which is comparable to that of a traditional battery module.The velocity of the thermal runaway propagation fluctuated between 1 and 8 mm s^(-1),depending on both the electrolyte content and high-temperature gas diffusion.In the early stages of thermal runaway,the electrolyte participated in the reaction,which intensified the thermal runaway and accelerated its propagation.As the battery temperature increased,the electrolyte evaporated,which attenuated the acceleration effect.Gas diffusion affected thermal runaway propagation through both heat transfer and mass transfer.The experimental results indicated that gas diffusion accelerated the velocity of thermal runaway propagation by 36.84%.We used a 1D mathematical model and confirmed that convective heat transfer induced by gas diffusion increased the velocity of thermal runaway propagation by 5.46%-17.06%.Finally,the temperature rate curve was analyzed,and a three-stage mechanism for internal thermal runaway propagation was proposed.In Stage I,convective heat transfer from electrolyte evaporation locally increased the temperature to 100℃.In Stage II,solid heat transfer locally increases the temperature to trigger thermal runaway.In StageⅢ,thermal runaway sharply increases the local temperature.The proposed mechanism sheds light on the internal thermal runaway propagation of blade batteries and offers valuable insights into safety considerations for future design.展开更多
The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the ...The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.展开更多
Early warning of thermal runaway(TR)of lithium-ion batteries(LIBs)is a significant challenge in current application scenarios.Timely and effective TR early warning technology is urgently required considering the curre...Early warning of thermal runaway(TR)of lithium-ion batteries(LIBs)is a significant challenge in current application scenarios.Timely and effective TR early warning technology is urgently required considering the current fire safety situation of LIBs.In this work,we report an early warning method of TR with online electrochemical impedance spectroscopy(EIS)monitoring,which overcomes the shortcomings of warning methods based on traditional signals such as temperature,gas,and pressure with obvious delay and high cost.With in-situ data acquisition through accelerating rate calorimeter(ARC)-EIS test,the crucial features of TR were extracted using the RReliefF algorithm.TR mechanisms corresponding to the features at specific frequencies were analyzed.Finally,a three-level warning strategy for single battery,series module,and parallel module was formulated,which can successfully send out an early warning signal ahead of the self-heating temperature of battery under thermal abuse condition.The technology can provide a reliable basis for the timely intervention of battery thermal management and fire protection systems and is expected to be applied to electric vehicles and energy storage devices to realize early warning and improve battery safety.展开更多
Developing technologies that can be applied simultaneously in battery thermal management(BTM)and thermal runaway(TR)mitigation is significant to improving the safety of lithium-ion battery systems.Inorganic phase chan...Developing technologies that can be applied simultaneously in battery thermal management(BTM)and thermal runaway(TR)mitigation is significant to improving the safety of lithium-ion battery systems.Inorganic phase change material(PCM)with nonflammability has the potential to achieve this dual function.This study proposed an encapsulated inorganic phase change material(EPCM)with a heat transfer enhancement for battery systems,where Na_(2)HPO_(4)·12H_(2)O was used as the core PCM encapsulated by silica and the additive of carbon nanotube(CNT)was applied to enhance the thermal conductivity.The microstructure and thermal properties of the EPCM/CNT were analyzed by a series of characterization tests.Two different incorporating methods of CNT were compared and the proper CNT adding amount was also studied.After preparation,the battery thermal management performance and TR propagation mitigation effects of EPCM/CNT were further investigated on the battery modules.The experimental results of thermal management tests showed that EPCM/CNT not only slowed down the temperature rising of the module but also improved the temperature uniformity during normal operation.The peak battery temperature decreased from 76℃to 61.2℃at 2 C discharge rate and the temperature difference was controlled below 3℃.Moreover,the results of TR propagation tests demonstrated that nonflammable EPCM/CNT with good heat absorption could work as a TR barrier,which exhibited effective mitigation on TR and TR propagation.The trigger time of three cells was successfully delayed by 129,474 and 551 s,respectively and the propagation intervals were greatly extended as well.展开更多
In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost ef...In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.展开更多
This paper presents a comprehensive treatment of the parametric sensitivity and runaway in fixed bed reactors with one dimensional pseudo homogeneous dispersion model (ODDM). In this case, we find the existence of m...This paper presents a comprehensive treatment of the parametric sensitivity and runaway in fixed bed reactors with one dimensional pseudo homogeneous dispersion model (ODDM). In this case, we find the existence of multiplicity and determine the runaway criterion through the critical isodisper sion curve. The calculated results indicate when the axial dispersion is relatively small, the impact of the axial dispersion on the parametric sensitivity may be neglected; but when the axial dispersion is large, this impact must be considered.展开更多
A simple one-dimensional numerical model including generation, acceleration and loss effects for runaway electrons are used to deduce the runaway energy εr. The simulation results are presented in a form of a scaling...A simple one-dimensional numerical model including generation, acceleration and loss effects for runaway electrons are used to deduce the runaway energy εr. The simulation results are presented in a form of a scaling law of εr on plasma parameters. The scaling of εr and therefore the runaway confinement time εr and runaway electron diffusivity Dr have been studied in HL-1M tokamak, by measuring the hard-X ray spectra under different experimental conditions. A tentative explanation for the scaling of obtained data based on the effects from magnetic turbulence is presented.展开更多
Runaway electrons in tokamaks have been widely studied theoretically and experimentally. The runaway confinement time τr in ohmic and additionally heated tokamak plasmas presents an anomalous behavior compared with t...Runaway electrons in tokamaks have been widely studied theoretically and experimentally. The runaway confinement time τr in ohmic and additionally heated tokamak plasmas presents an anomalous behavior compared with theoretical predictions based on neoclassical models. A one-dimensional numerical model including generation, acceleration and loss effect of runaway electrons is used to deduce the runaway energy εr dependence on the runaway confinement time.展开更多
During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. ...During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors： electroh cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.展开更多
文摘This study shows that sulfide solid-state electrolytes,β-Li_(3)PS_(4)and Li_(6)PS_(5)Cl,are flammable solids.Both solid-state electrolytes release sulfur vapor in a dry,oxidizing environment at elevated temperature<300℃.Sulfur vapor is a highly flammable gas,which then auto-ignites to produce a flame.This behavior suggests that an O_(2)-S gas-gas reaction mechanism may contribute to all-solid-state battery thermal runaway.To improve all-solid-state battery safety,current work focuses on eliminating the O_(2)source by changing the cathode active material.The conclusion of this study suggests that all-solidstate battery safety can also be realized by the development of solid-state electrolytes with less susceptibility to sulfur volatilization.
文摘This study focuses on the thermal management of 4680-type cylindrical lithium-ion battery packs utilizing NCM811 chemistry.It establishes coupled multi-physics models for both immersion and serpentine cold plate cooling systems.Through a combination of numerical simulation and experimental validation,the technical advantages and mechanisms of immersion cooling are systematically explored.Simulation results indicate that under a 3C fast-charging condition(inlet temperature 20℃,flow rate 36 L/min),the immersion cooling structure 3demonstrates a triple enhancement in thermal performance compared to the cold plate structure 1:a 13.06%reduction in peak temperature,a 31.67%decrease in overall maximum temperature difference,and a 47.62%decrease in single-cell temperature deviation,while also reducing flow resistance by 33.61%.Furthermore,based on the immersion cooling model,a small battery module comprising seven cylindrical cells was designed for thermal runaway testing via nail penetration.The results show that the peak temperature of the triggered cell was limited to 437.6℃,with a controllable temperature rise gradient of only 3.35℃/s and a rapid cooling rate of 0.6℃/s.The maximum temperature rise of adjacent cells was just 64.8℃,effectively inhibiting thermal propagation.Post-test disassembly revealed that the non-triggered cells retained>99.2%of their original voltage and>99%structural integrity,confirming the module’s ability to achieve“localized failure with global stability.”
基金supported by the National Natural Science Foundation of China(Grant No.92372111 and 22179070)the Fundame ntal Research Funds for the Central Universities(Grant No.RF1028623157)the SEU Innovation Capability Enhancement Plan for Doctoral Students(CXJH_SEU 24063)。
文摘Anode binders undergo decomposition during thermal runaway,generating highly flammable and explosive hydrogen,which poses a significant threat to the safety of lithium-ion batteries.However,the binder due to its relatively small proportion is often overlooked in terms of its importance.This study elucidates the universal mechanism of hydrogen generation from the decomposition of binders and identifies the hydrogen-containing chemical bonds within the molecular structure of binders as the fundamental sources of hydrogen.The Fourier transform infrared spectroscopy of six commonly used binders reveals that five of them possess hydrogen-containing chemical bonds,indicating a potential for hydrogen generation,whereas the polytetrafluoroethylene binder lacks such bonds and cannot generate hydrogen.Differential scanning calorimetry is employed to compare the decomposition of these binders and their reaction with lithiated graphite.The results demonstrate that cyclic molecular structures not only enhance thermal stability but also increase the difficulty of hydrogen generation.Moreover,binders devoid of hydrogen atoms exhibit superior thermal stability and completely eliminate the risk of hydrogen generation.These findings provide critical insights into the molecular design of binders,offering promising strategies to mitigate or prevent hydrogen generation from binder decomposition and thereby substantially improve the safety of lithium-ion batteries.
基金supported in part by the National Key R&D Program of China (No.2022YFE03040002)the Natural Science Foundation of Sichuan (No.2022NSFSC1814)+3 种基金National Natural Science Foundation of China (Nos.12305246,12175053 and 12261131622)the Italian Ministry of Foreign Affairs (No.CN23GR02)the Fundamental Research Funds for the Central Universitiessupported by US Department of Energy (No.DE-AC0209CH11466)。
文摘This study investigates the influence of runaway current in runaway plasmas on the dynamics of sawtooth oscillations and resultant loss of runaway electrons(RE)using the 3D magnetohydrodynamic(MHD)code M3D-C^(1)(Jardin et al 2012 J.Comput.Sci.Discovery 6014002).Using an HL-2A-like equilibrium,we confirm that in the linear phase,the impact of REs on resistive internal kink instabilities is consistent with previous research.In the nonlinear phase,as the runaway current fully replaces the plasmas current,we observe a significant suppression of sawtooth oscillations,with the first sawtooth cycle occurring earlier compared to the case without runaway current.Following the first sawtooth collapse,plasma current density,runaway current density,and safety factor(q)flatten within the q=1 surface,albeit displaying fine structures.Subsequently,the growing high torodial(n)and poloidal(m)mode number modes disrupt the magnetic surfaces,leading to the loss of REs outside the q=1 surface,while minimally affecting the majority of REs well-confined within it.Thus,in the current model,the physical processes associated with the presence of sawtooth oscillations do not effectively dissipate runaway current,as REs are assumed to be collisionless.In addition,the final profile of runaway current density exhibits increased steepening near the q=1 surface in contrast to the initial profile,displaying a distinctive corrugated inhomogeneity influenced by the growing fluctuation of the n=0 component.Finally,detailed convergence tests are conducted to validate the numerical simulations.
基金supported by the National Natural Science Foundation of China(52106284,52422609)the Natural Science Foundation of Hebei Province(B2021507001)Key Research Special Project of CPPU(ZDZX202501)。
文摘As lithium-ion batteries(LIBs)continue to evolve toward lower costs and higher energy densities,their potential safety risks have become increasingly apparent.Incidents such as explosions at energy storage facilities,fires in electric vehicles,and building fires ignited by charging two-wheeled vehicles have been occurring with alarming frequency,often resulting in significant casualties and injuries.Conducting indepth investigations into thermal runaway(TR)incidents in LIBs can significantly reduce the risk of future occurrences.However,current investigations into LIB fire and explosion incidents face challenges due to the difficulty of conducting in-depth analyses and the lack of a robust theoretical framework to guide these investigations.To enhance the effectiveness of in-depth investigations into battery fire and explosion incidents and to address the lack of theoretical guidance,this paper is the first to systematically examine the conservation and flow patterns of elements during the TR process of LIBs.The analysis reveals that during TR,the gas products generated include approximately 1.5 g of H_(2),23.6 g of CO,88.4 g of CO_(2),8.9 g of C_(2)H_(4),7.3 g of CH_(4),3.7 g of C_(2)H_(6),and 82 g of electrolyte vapor.After TR,the solid compounds formed consist of approximately 2.5 g of LiF,29–92.2 g of elemental Ni/Co/Mn,11.4 g of Li_(2)CO_(3),200.6 g of graphite,1.4 g of NiO,29.6 g of MnO,30.1 g of CoO,67 g of elemental Cu,0.03 g of LiNiO_(2),and 4.3 g of LiAlO_(2).Importantly,the energy released from reactions forming solid compounds during TR surpasses that from gas-forming reactions.This investigation represents the first application of Hess’s law to verify the conservation of elements during the TR process of lithium-ion batteries.The proposed methodology is also applicable to other types of energy storage batteries,effectively advancing techniques for comprehensively investigating lithium battery fire and explosion incidents.
基金financial support from the National Natural Science Foundation of China(Nos.52325801,52402052)。
文摘Thermal runaway(TR)in lithium-ion batteries(LIBs)poses significant safety risks due to its potential to trigger fires and explosions.Early warning of battery TR through gas sensing has emerged as a promising strategy for hazard mitigation.However,comprehensive reviews critically summarizing recent progress in advanced gas sensing technologies remain scarce.To fill this void,we present a critical review consolidating state-of-the-art advancements in gas sensing for TR early warning.This review first overviews the fundamentals of gas sensing for TR monitoring,encompassing thermodynamics and kinetic principles of gas evolution alongside current gas sensing technologies.We then comprehensively explored multi-scale engineering methods,spanning material innovations,device configurations,and system-level integration,with an emphasis on cutting-edge techniques like additive manufacturing and data-driven design frameworks.Future research priorities are identified,including the enhancement of gas selectivity and environmental robustness,the development of machine learning-driven intelligent gas sensing networks,and the establishment of standardized protocols for practical deployment.By integrating interdisciplinary insights derived from materials science,electrochemistry,and embedded systems engineering,this review is positioned to offer actionable guidelines for advancing scalable and reliable gas-sensing solutions toward boosted LIB safety.
基金supported by the National Key R&D Program of China(No.2024YFE0209200)National Natural Science Foundation of China(No.52404259)+1 种基金Postgraduate Academic Innovation Project of Anhui Province(No.2023xscx009)supported by Youth Innovation Promotion Association CAS(No.Y201768)。
文摘Sodium-ion batteries have gradually been commercialized due to their wide range of material sources and low cost.However,there are few studies focusing on the commercial sodium-ion battery safety,especially the relationship between heat and gas generation is unclear.This work conducts the thermal runaway(TR)experiments of commercial 18650 sodium-ion batteries with different states of charge(SOCs)under adiabatic accelerated rate calorimetry and localized overheating.The results show that heat generation values of 50% and 100%SOC batteries during TR are 175.2 and 328.2 J g^(-1),respectively.Whereas,0%SOC batteries do not trigger TR.Moreover,the reaction sources and pathways of gas generation during TR are critically sorted out.Finally,two important conclusions are obtained.(i)During the five stages of TR,the heat generation from the safe venting to the triggering of TR stage is the highest in 50%SOC batteries,accounting for 62.5% of the total heat generation.However,for 100%SOC batteries,the heat generation from triggering TR to maximum temperature stage has the largest proportion during TR,at 57%.The 50%SOC batteries present characteristic of slow heat generation,while the 100%SOC batteries show characteristics of accelerated heat generation.(ii)Based on dimensionless analysis,the heat/gas generation ratios of 50% and 100%SOC batteries are 0.262 and 0.028,respectively.The gas generation behavior occur earlier than heat generation behavior during the whole process of TR of sodium-ion batteries.This study provides a direction for the development of high-safety sodium-ion batteries and thermal runaway suppression technology.
基金supported by the National Key R&D Program of China(2023YFB2407900)the National Natural Science Foundation of China(52302512)+1 种基金State Key Laboratory of New Ceramic and Fine Processing Tsinghua University(KFZD202305)Zhejiang Province Science and Technology Program Grant(2024C0127(SD2))。
文摘Cascading thermal runaway(TR)propagation poses a critical safety concern for large-format sodium-ion battery(SIB)systems because of the heightened risks of fires or explosions.However,effectively suppressing TR propagation without introducing unintended side effects remains a significant challenge.Herein,we demonstrate a localized energy release method to mitigate TR,by reducing the state of charge(SOC)of cells adjacent to the thermally runaway unit.We discover that as the SOCs decreased from 100%to 25%,the TR trigger temperature decreased significantly,and the maximum temperature decrease from 367 to 229℃.Meanwhile,the volume of gas decreased to one-third of its original value,while the range of explosion limits significantly narrowed.The analysis of the morphology of the debris further confirms that the structural damage is greater at higher SOC levels.Moreover,an Entropy Weight and Technique for Order Preference by Similarity to an Ideal Solution(EW-TOPSIS)method has been established to assess the safety status of SIBs,showing that the TR possibility is nearly linear with the SOCs,and the TR hazard is exponentially related to the SOCs.Finally,when the SOC of cells adjacent to the TR cell is reduced to 25%,TR can be directly blocked without the need for additional cooling or thermal insulation methods.This study not only advances the understanding of TR behavior in SIBs but also offers a straightforward approach to mitigating the TR risk in SIB systems.
基金the Faraday Institution’s SafeBatt(https://www.safebatt.ac.uk/)project[grant numbers:EP/S003053/1,FIRG061]DSIT and the Royal Academy of Engineering,under the Chair in Emerging Technologies Scheme(CiET1718/59)。
文摘Thermal runaway(TR)in lithium-ion batteries(LIBs)involves a complicated multiphysics process with potentially catastrophic consequences,highlighting the importance of investigating effective prevention strategies.This study employs a lumped model integrating electrochemical and decomposition reaction kinetics to predict the evolution of the TR of LIBs triggered by axial nail penetration,validated by experimental tests.A computational fluid dynamics(CFD)-based turbulent flow model is further employed to simulate the thermal runaway propagation(TRP)behavior induced by high-temperature gases within the battery module.A parameterized analysis based on numerical simulation is conducted to quantify the impact of thermal insulation material properties on thermal diffusion and heat accumulation within the module.The results indicate that damage to the battery vent significantly increases the risk of sidewall rupture during TR.The incorporation of thermal barriers is essential in the thermal design of battery modules to prevent heat transfer via convection from the thermal exhaust caused by sidewall rupture to adjacent cells.In addition,a reduction in the thermal diffusivity of the thermal barrier material is required to minimize thermal exchange between battery cells.By adopting insulating materials with thermal diffusivity lower than 0.3 mm^(2)/s,the TRP of batteries can be mitigated under non-enclosed conditions.These findings contribute to improved battery safety and inform the development of more effective thermal protection measures and safety standards.
基金supported by the National Key Research and Development Plan(2023YFC3009900)the National Natural Science Foundation of China(52104197,52272396,52474233)+3 种基金Hongkong Scholar Program(XJ2022022)Research Grants Council of the Hong Kong Special Administrative Region(City U11214221)Natural Science Foundation of the Jiangsu Higher Education Institutions(21KJB620001)the Open Fund of the State Key Laboratory of Fire Science(SKLFS)Program(HZ2022-KF04)。
文摘In this work,a series of experiments are carried out to investigate the effect of charge/discharge rates(1,2,3 and 4 C)and state of charges(SOCs,namely 0%,50%,75%and 100%)on thermal runaway(TR)and fire behavior of lithium iron phosphate(LFP)batteries.The TR process caused by overheating LFP batteries is usually divided into four stages,with high temperatures and fire risks.High-rate charge and discharge damage the internal morphology and structural stability of materials seriously.The TR behavior of battery is fully aggravated,which is further manifested by the advanced opening of the safety vent,release of gas and occurrence of TR.With the increase of charging rate,the deteriorated TR characteristics can be discerned,such as the lower TR temperature,the shorter TR time,and the more serious TR consequences.Such changes can be assigned to the decline of battery stability.In addition,the battery SOC greatly impacts safety,especially the flame temperature and the severity of consequences.As for the 100%SOC battery cycled at 4 C,there is still a high risk of thermal runaway propagation at the position 1 m far away from the battery.This work helps to realize the TR and fire features of battery in-depth,enlightening the safety protection of battery.
基金supported by the National Magnetic Confinement Fusion Energy R&D Program of China (Nos.2018YFE0309103 and 2019YFE03010004)National Natural Science Foundation of China (Nos.12475222,12205122,and 51821005)Hubei International Science and Technology Cooperation Projects (No.2022EHB003)。
文摘A large number of runaway electrons(REs)generated during disruption can cause significant damage to next-generation large-scale tokamaks.The influence of three-dimensional(3D)helical magnetic perturbations on the suppression of RE generation was explored using a set of 3D helical coils in J-TEXT tokamak,which can excite m/n=-2/2 helical magnetic perturbations.Experimental evidence shows that the-2/2 magnetic perturbations caused by the opposite coil current direct plasma toward the high-field side,simultaneously enhancing the magnetic fluctuations,which would enhance the radial loss of REs and even prevent RE generation.On the other hand,-2/2 magnetic perturbations can also reduce the cooling time during the disruption phase and generate a population of high-energy REs,which can interact with high-frequency magnetic fluctuations and in turn suppress RE generation.The critical helical coil current was found to correlate with electron density,requiring higher coil currents at higher densities.According to the statistical analysis of RE generation at different electron densities,the applied-2/2 magnetic perturbations can increase the magnetic fluctuations to the same level at lower electron densities,which can decrease the threshold electron density for RE suppression.This will be beneficial for RE mitigation in future large tokamak devices.
基金supported by the National Key R&D Program-Strategic Scientific and Technological Innovation Cooperation(Grant No.2022YFE0207900)the National Natural Science Foundation of China(Grant Nos.51706117,52076121)。
文摘Blade batteries are extensively used in electric vehicles,but unavoidable thermal runaway is an inherent threat to their safe use.This study experimentally investigated the mechanism underlying thermal runaway propagation within a blade battery by using a nail to trigger thermal runaway and thermocouples to track its propagation inside a cell.The results showed that the internal thermal runaway could propagate for up to 272 s,which is comparable to that of a traditional battery module.The velocity of the thermal runaway propagation fluctuated between 1 and 8 mm s^(-1),depending on both the electrolyte content and high-temperature gas diffusion.In the early stages of thermal runaway,the electrolyte participated in the reaction,which intensified the thermal runaway and accelerated its propagation.As the battery temperature increased,the electrolyte evaporated,which attenuated the acceleration effect.Gas diffusion affected thermal runaway propagation through both heat transfer and mass transfer.The experimental results indicated that gas diffusion accelerated the velocity of thermal runaway propagation by 36.84%.We used a 1D mathematical model and confirmed that convective heat transfer induced by gas diffusion increased the velocity of thermal runaway propagation by 5.46%-17.06%.Finally,the temperature rate curve was analyzed,and a three-stage mechanism for internal thermal runaway propagation was proposed.In Stage I,convective heat transfer from electrolyte evaporation locally increased the temperature to 100℃.In Stage II,solid heat transfer locally increases the temperature to trigger thermal runaway.In StageⅢ,thermal runaway sharply increases the local temperature.The proposed mechanism sheds light on the internal thermal runaway propagation of blade batteries and offers valuable insights into safety considerations for future design.
基金supported by the National Key R&D Program of China(No.2021YFB2402001)the Postgraduate Innovation and Entrepreneurship Practice Project of Anhui Province(No.2022cxcysj013)+2 种基金the China Postdoctoral Science Foundation(No.2022T150615)the Fundamental Research Funds for the Central Universities(No.WK5290000002)supported by Youth Innovation Promotion Association CAS(No.Y201768)。
文摘The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.
基金supported by the National Natural Science Foundation of China(U2033204,51976209)the Natural Science Foundation of Hefei(2022019)supported by Youth Innovative Promotion Association CAS(Y201768)。
文摘Early warning of thermal runaway(TR)of lithium-ion batteries(LIBs)is a significant challenge in current application scenarios.Timely and effective TR early warning technology is urgently required considering the current fire safety situation of LIBs.In this work,we report an early warning method of TR with online electrochemical impedance spectroscopy(EIS)monitoring,which overcomes the shortcomings of warning methods based on traditional signals such as temperature,gas,and pressure with obvious delay and high cost.With in-situ data acquisition through accelerating rate calorimeter(ARC)-EIS test,the crucial features of TR were extracted using the RReliefF algorithm.TR mechanisms corresponding to the features at specific frequencies were analyzed.Finally,a three-level warning strategy for single battery,series module,and parallel module was formulated,which can successfully send out an early warning signal ahead of the self-heating temperature of battery under thermal abuse condition.The technology can provide a reliable basis for the timely intervention of battery thermal management and fire protection systems and is expected to be applied to electric vehicles and energy storage devices to realize early warning and improve battery safety.
基金financially supported by the National Key Research and Development Program(Grant No.2022YFE0207400)the National Natural Science Foundation of China(Grant No.U22A20168 and 52174225)。
文摘Developing technologies that can be applied simultaneously in battery thermal management(BTM)and thermal runaway(TR)mitigation is significant to improving the safety of lithium-ion battery systems.Inorganic phase change material(PCM)with nonflammability has the potential to achieve this dual function.This study proposed an encapsulated inorganic phase change material(EPCM)with a heat transfer enhancement for battery systems,where Na_(2)HPO_(4)·12H_(2)O was used as the core PCM encapsulated by silica and the additive of carbon nanotube(CNT)was applied to enhance the thermal conductivity.The microstructure and thermal properties of the EPCM/CNT were analyzed by a series of characterization tests.Two different incorporating methods of CNT were compared and the proper CNT adding amount was also studied.After preparation,the battery thermal management performance and TR propagation mitigation effects of EPCM/CNT were further investigated on the battery modules.The experimental results of thermal management tests showed that EPCM/CNT not only slowed down the temperature rising of the module but also improved the temperature uniformity during normal operation.The peak battery temperature decreased from 76℃to 61.2℃at 2 C discharge rate and the temperature difference was controlled below 3℃.Moreover,the results of TR propagation tests demonstrated that nonflammable EPCM/CNT with good heat absorption could work as a TR barrier,which exhibited effective mitigation on TR and TR propagation.The trigger time of three cells was successfully delayed by 129,474 and 551 s,respectively and the propagation intervals were greatly extended as well.
基金support by,National Key Research and Development Program(2023YFB2503700 and 2023YFC3008804)the Beijing Municipal Science&Technology Commission No.Z231100006123003+1 种基金the National Science Foundation of China(22071133)the Beijing Natural Science Foundation(No.Z220020).
文摘In recent years,the new energy storage system,such as lithium ion batteries(LIBs),has attracted much attention.In order to meet the demand of industrial progress for longer cycle life,higher energy density and cost efficiency,a quantity of research has been conducted on the commercial application of LIBs.However,it is difficult to achieve satisfying safety and cycling performance simultaneously.There may be thermal runaway(TR),external impact,overcharge and overdischarge in the process of battery abuse,which makes the safety problem of LIBs more prominent.In this review,we summarize recent progress in the smart safety materials design towards the goal of preventing TR of LIBs reversibly from different abuse conditions.Benefiting from smart responsive materials and novel structural design,the safety of LIBs can be improved a lot.We expect to provide a comprehensive reference for the development of smart and safe lithium-based battery materials.
文摘This paper presents a comprehensive treatment of the parametric sensitivity and runaway in fixed bed reactors with one dimensional pseudo homogeneous dispersion model (ODDM). In this case, we find the existence of multiplicity and determine the runaway criterion through the critical isodisper sion curve. The calculated results indicate when the axial dispersion is relatively small, the impact of the axial dispersion on the parametric sensitivity may be neglected; but when the axial dispersion is large, this impact must be considered.
文摘A simple one-dimensional numerical model including generation, acceleration and loss effects for runaway electrons are used to deduce the runaway energy εr. The simulation results are presented in a form of a scaling law of εr on plasma parameters. The scaling of εr and therefore the runaway confinement time εr and runaway electron diffusivity Dr have been studied in HL-1M tokamak, by measuring the hard-X ray spectra under different experimental conditions. A tentative explanation for the scaling of obtained data based on the effects from magnetic turbulence is presented.
文摘Runaway electrons in tokamaks have been widely studied theoretically and experimentally. The runaway confinement time τr in ohmic and additionally heated tokamak plasmas presents an anomalous behavior compared with theoretical predictions based on neoclassical models. A one-dimensional numerical model including generation, acceleration and loss effect of runaway electrons is used to deduce the runaway energy εr dependence on the runaway confinement time.
基金Project supported by the National Natural Science Foundation of China (Grant Nos 10675124,10775041 and 10775045)
文摘During the current flat-top phase of electron cyclotron resonance heating discharges in the HL-2A Tokamak, the behaviour of runaway electrons has been studied by means of hard x-ray detectors and neutron diagnostics. During electron cyclotron resonance heating, it can be found that both hard x-ray radiation intensity and neutron emission flux fall rapidly to a very low level, which suggests that runaway electrons have been suppressed by electron cyclotron resonance heating. From the set of discharges studied in the present experiments, it has also been observed that the efficiency of runaway suppression by electron cyclotron resonance heating was apparently affected by two factors： electroh cyclotron resonance heating power and duration. These results have been analysed by using a test particle model. The decrease of the toroidal electric field due to electron cyclotron resonance heating results in a rapid fall in the runaway electron energy that may lead to a suppression of runaway electrons. During electron cyclotron resonance heating with different powers and durations, the runaway electrons will experience different slowing down processes. These different decay processes are the major cause for influencing the efficiency of runaway suppression. This result is related to the safe operation of the Tokamak and may bring an effective control of runaway electrons.
