The corrosion behavior and life of Sn−3.0Ag−0.5Cu solder joints were investigated through fire smoke exposure experiments within the temperature range of 45−80℃.The nonlinear Wiener process and Arrhenius equation wer...The corrosion behavior and life of Sn−3.0Ag−0.5Cu solder joints were investigated through fire smoke exposure experiments within the temperature range of 45−80℃.The nonlinear Wiener process and Arrhenius equation were used to establish the probability distribution function and prediction model of the solder joint’s average life and individual remaining useful life.The results indicate that solder joint resistance shows a nonlinear growth trend with time increasing.After 24 h,the solder joint transforms from spherical to rose-like shapes.Higher temperatures accelerate solder joint failure,and the relationship between failure time and temperature conforms to the Arrhenius equation.The predicted life of the model is in good agreement with experimental results,demonstrating the effectiveness and accuracy of the model.展开更多
The high energy density of lithium metal batteries(LMBs)has attracted widespread attention,which is expected to improve the endurance mileage of electric vehicles comparable to fossil fuel-powered vehicles.At present,...The high energy density of lithium metal batteries(LMBs)has attracted widespread attention,which is expected to improve the endurance mileage of electric vehicles comparable to fossil fuel-powered vehicles.At present,the main research is focused on developing advanced materials and revealing the indepth electrochemical mechanism of LMBs,while there is a significant lagging behind of attention to the safety evaluation.This review aims to emphasize the fire safety challenges faced by LMBs and summarize advanced strategies for improving intrinsic safety.Firstly,the basic chemical composition and working principle of LMBs were introduced compared with lithium-ion batteries.Moreover,we reviewed the thermal runaway problem of LMBs from the aspects of material activity,interfacial stability triggering conditions,thermal runaway behavior and mechanism,the special thermal runaway characteristics,and new safety challenges of Li-S,Li-O_(2),and the solid-state LMBs were discussed in detail.Based on the analysis of the thermal runaway mechanism,we summarized the advanced strategies,including electrolyte design,interphase film construction,separator,and anode design for improving the intrinsic safety of LMBs.Finally,we proposed the fire safety challenge at the battery level and emphasized the necessity of designing safe materials based on the thermal runaway mechanism.Blocking the thermal coupling reaction and conducting multi-strategy collaborative optimization is the key point to restrain thermal runaway.展开更多
Pressurized buildings have emerged as a novel architectural solution to alleviate altitude illness in high-altitude regions.Unlike conventional buildings,evacuation from this kind of building has to experience a depre...Pressurized buildings have emerged as a novel architectural solution to alleviate altitude illness in high-altitude regions.Unlike conventional buildings,evacuation from this kind of building has to experience a depressurization time,which results in air expansion and heat absorption,creating a dense fog and impairing sight within the buildings.Evacuation experiments were performed in a pressurized oxygen-supplement compartment to investigate the pedestrian motion properties.Based on the questionnaires,participants reported varying degrees of symptoms such as ear blockage,reduced environmental noise,and dizziness,which had a measurable impact on their mobility.We focus on the evacuation parameters through three basic building components:staircases,pressure transition cabins,and escape windows.As the visibility in the compartment decreases from high to low,the movement patterns of pedestrian shift from triangular to single-file with a significant decline in evacuation efficiency.It is found that there is a linear relationship between evacuation time and the number of evacuees through escape windows.The pressure transition cabin is a crucial evacuation route in emergencies,and evacuation time is recommended as the key metric for assessing its effectiveness.These findings offer valuable insights for emergency evacuation strategies in pressurized buildings.展开更多
Currently,the effective and clean suppression of lithium-ion battery(LIB)fires remains a challenge.The present work investigates the use of various inhibitor doses(Xin)of dodecafluoro-2-methylpentan-3-one(C_(6) F_(12)...Currently,the effective and clean suppression of lithium-ion battery(LIB)fires remains a challenge.The present work investigates the use of various inhibitor doses(Xin)of dodecafluoro-2-methylpentan-3-one(C_(6) F_(12)O)in 300 Ah LIBs,and systematically examines the thermal and toxic hazards of the extinguished batteries via real scale combustion and gas analysis.The inhibitor is shown to be completely effective.The inhibition mechanism involves a combination of chemical inhibition and physical cooling.While the chemical inhibition effect tends to saturate with increasing Xin,the physical cooling remains effective at higher inhibitor doses.However,extinguishing the battery fire with a high Xin of C_(6)F_(12)O is found to incur serious toxicity problems.These results are expected to provide a guideline for the design of inhibitor doses for the suppression of LIB fires.展开更多
The high fire safety of polymer nanocomposites is being pursued by research institutions around the world.In addition to intrinsic flame retardancy strategy,the additive-type flame retardants have attracted increasing...The high fire safety of polymer nanocomposites is being pursued by research institutions around the world.In addition to intrinsic flame retardancy strategy,the additive-type flame retardants have attracted increasing attention due to low commercial cost and easy fabrication craft.However,traditional additive-type flame retardants usually need high addition amount to achieve a desirable effect which causes many side-effects on the overall performance of polymer materials,such as deteriorated mechanical property and processability.At present two-dimensional(2D)nanomaterials have also been applied to reduce the fire hazards of polymer(nano)composites with the coupling of barrier function and catalysis as well as carbonization effect.Even though most research work mainly focus on graphene-based flame retardants,more emerging two-dimensional nanomaterials are taking away research attention,due to their complementary and unique properties,mainly including hexagonal boron nitride(h-BN),molybdenum disulfide(MoS2),metal organic frameworks(MOF),carbon nitride(CN),titanium carbide(MXene)and black phosphorene(BP).In this review,except for graphene,the flame retardant mechanism involving different layered nanomaterials are also reviewed.Meanwhile,the functionalization method and flame retardancy effect of different layered nanomaterials are emphatically discussed for offering an effective reference to solve the fire hazards of polymer materials.Moreover,this work objectively evaluates the practical significance of polymer/layered nanomaterials composites for industrial application.展开更多
Since serious fire occurred frequently in recent years, fire safety of high-rise building has attracted extensive attention. A National Basic Research Program （973 program） of China has been set up by Ministry of Sc...Since serious fire occurred frequently in recent years, fire safety of high-rise building has attracted extensive attention. A National Basic Research Program （973 program） of China has been set up by Ministry of Science and Technology （MOST） of China in 2012 to meet the research requirements of fire safety in high-rise buildings. This paper reviews the current state of art of research on fire dynamics of high-rise buildings, including the up-to-date progress of this project. The following three subjects on fire dynamics of high-rise buildings are addressed in this review： the ejected flame and fire plume behavior over facade out of the compartment window, the flame spread behavior over facade thermal insulation materiMs, and the buoyancy-driven smoke transportation characteristics along long vertical channels in high-rise buildings. Prospective future works are discussed and summarized.展开更多
Biomass phytic acid has potential flame retardant value as the main form of phosphorus in plant seeds.In this study,phytate-based flame retardants aluminum phytate(PA-Al)and iron phytate(PA-Fe)were synthesized and cha...Biomass phytic acid has potential flame retardant value as the main form of phosphorus in plant seeds.In this study,phytate-based flame retardants aluminum phytate(PA-Al)and iron phytate(PA-Fe)were synthesized and characterized.Subsequently,they were introduced into rigid polyurethane foam(RPUF)as flame retardants by one-step water-blown method.The results indicated that RPUF/PA-Fe30 exhibited the highest char residue of 22.1 wt%,significantly higher than 12.4 wt%of RPUF.Cone calorimetry analysis showed that the total heat release(THR)of RPUF/PA-Al30 decreased by 17.0%and total smoke release(TSR)decreased by 22.0%compared with pure RPUF,which were the lowest,demonstrating a low fire risk and good smoke suppression.Thermogravimetric analysis-Fourier transform infrared spectrometer(TG-FTIR)implied the release intensity of flammable gases(hydrocarbons,esters)and toxic gases(isocyanate,CO,aromatic compounds,HCN)of composites was significantly reduced after the addition of PA-Fe.The analysis of char residue indicated that the RPUF composites formed a dense char layer with a high degree of graphitization after the addition of PA-Al/PA-Fe,endowing RPUF composites with excellent mass&heat transmission inhibition effect and fire resistance in the combustion process.展开更多
Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typica...Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.展开更多
Forest fire accidents caused by distribution line faults occur frequently,resulting in heavy impacts on people’s safety and social and economic development.Currently,there are few risk assessments for forest fires in...Forest fire accidents caused by distribution line faults occur frequently,resulting in heavy impacts on people’s safety and social and economic development.Currently,there are few risk assessments for forest fires induced by over-head distribution lines,and existing assessment methods may have difficulties in data acquisition.On this basis,a novel as-sessment framework based on an analytic hierarchy process,a Bayesian network and a Fussel-Vesely importance metric is proposed in this paper.The framework combines field research and historical operation and maintenance data to assess the regional-scale risk of forest fires induced by overhead distribution lines to derive the probability of forest fires and to identify high-risk lines and key hazard events in the assessment region.Finally,taking the southern Anhui region as an ex-ample,the annual fire probability of forest fires induced by overhead distribution lines in the southern Anhui region is 5.88%,and rectification measures are proposed.This study provides management with a complete assessment framework that optimizes the difficulty of data collection and allows for additional targeted corrective measures to be proposed for the entire region and route on the basis of the assessment results.展开更多
Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives...Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.展开更多
Biomolecular self-assembly has lately emerged as an intriguing method for creating stable gas-liquid dis-persions with unique functional characteristics.In this work,protein-metal coordination complexes were designed ...Biomolecular self-assembly has lately emerged as an intriguing method for creating stable gas-liquid dis-persions with unique functional characteristics.In this work,protein-metal coordination complexes were designed as the stabilizer for generating ultrastable fire-fighting foam and creating interfacial architec-tures that were actively switched between"rigid"and"mobile"interfacial states of liquid films in re-sponse to changes in pH and bulk solution compositions(metal ions or alkyl polyglycosides).The re-flected light interferometric technique was used to check interfacial states,and the foaming kinetics and rheological response of aqueous solution and liquid foam were investigated by dynamic surface tension tests and oscillatory rheology analysis.The results showed that liquid foams with mobile films with lower yield limits had a faster spreading rate to cover the burning oil,liquid foams with semi-rigid films can-not extinguish fires due to interfacial instability,and the enhanced rheology of the foam with rigid films established a robust and impenetrable barrier to effectively suppress fuel evaporation and combustion.A new correlation between interfacial properties and the fire-fighting performance of foam was proposed,which showed that the fire-extinguishing time of foam could be well correlated by the interfacial states or film lifetime rather than classical thermodynamics entry,spreading,and bridging coefficients(ESB co-efficients).展开更多
In order to investigate the behavior of external welded flange-bolted web joints of steel structure exposed to fire,a series of experiments were carried out.Influence of fire model and load ratio on the behavior of th...In order to investigate the behavior of external welded flange-bolted web joints of steel structure exposed to fire,a series of experiments were carried out.Influence of fire model and load ratio on the behavior of the joints,failure characteristics and fracture modes of the joints exposed to fire were studied.The experimental results indicated that the fire model has a great influence on the temperature rising as well as temperature distribution of the joints exposed to fire.A slower temperature rising fire will lead to slower temperature rising and more uniform temperature distribution of joint.Decrease of the load ratio will improve the fire-resistant capability of the joint.Furthermore,a highly detailed three-dimensional(3-D) finite element model(FEM) was set up with ANSYS software to predict the behavior of the external welded flange-bolted web joints exposed to fire.Comparisons between the predicted results and the experimental results indicated that FEM has an acceptable degree of accuracy to predict the behavior of this type of joints exposed to fire.展开更多
In this work,a bio-based flame retardant(Cy-HEDP)was synthesized from cytosine and HEDP through a facile salt-forming reaction and embedded into epoxy matrix to improve the flame retardancy and smoke suppression perfo...In this work,a bio-based flame retardant(Cy-HEDP)was synthesized from cytosine and HEDP through a facile salt-forming reaction and embedded into epoxy matrix to improve the flame retardancy and smoke suppression performance.The product Cy-HEDP was well characterized by FTIR,^(1)H and^(31)P NMR and SEM tests.On the basis of the results,by adding 15 wt%Cy-HEDP,the EP15 can pass UL-94 V-0 rating,and the total smoke production(TSP)as well as total heat release(THR)can be decreased by 61.05%(from 22.61 to 8.7 m^(2)/m^(2))and 39.44%(from 103.19 to 62.50 MJ/m^(2))in comparison to the unfilled EP,reflecting the attenuated smoke toxicity and impeded heat generation.According to the analysis results of residual char,it can be concluded that Cy-HEDP possessed the ability to promote the formation of continuous and dense char layers,which would be a physical barrier to insulate oxygen and prevent heat feedback during the combustion of EP.This work provide inspiration towards developing bio-based flame retardant,probably extending the prospects to other polymeric material system.展开更多
With rapid economic and social development in China, high-rise buildings have continuously sprung up since 2006. However, several big fire accidents in high-rise buildings such as the Beijing Television Cultural Cente...With rapid economic and social development in China, high-rise buildings have continuously sprung up since 2006. However, several big fire accidents in high-rise buildings such as the Beijing Television Cultural Center fire in 2009 and the Shanghai Jing＇an District fire in 2010 etc. have claimed people＇s lives and caused huge amounts of economic and property losses,展开更多
To solve the fire accidents caused by coal combustion,this work prepared four hybrid hydrogel materials using bio-based polymers,flame retardants,and inorganic materials.Compared to pure water and 3.5 wt%MgCl_(2)solut...To solve the fire accidents caused by coal combustion,this work prepared four hybrid hydrogel materials using bio-based polymers,flame retardants,and inorganic materials.Compared to pure water and 3.5 wt%MgCl_(2)solution,the as-prepared hydrogel presents good fire prevention performance.In addition,it is found that CO and CO_(2)are not produced by coal when the pyrolysis temperature is lower than 200℃.During low-temperature pyrolysis,CO is more likely to be produced than CO_(2),indicating inadequate pyrolysis behavior.At the same time,the addition of fire-preventing hydrogel can not only decrease the maximum CO_(2)concentration before the critical temperature but also prolong the corresponding time.In addition,based on the cone calorimeter test,the inhibition effects of pure water,magnesium chloride solution,and four hybrid hydrogels on heat release behavior are evaluated.It is demonstrated that different dosages of different hydrogels affected the fire prevention effect.Phosphorous-modified cellulose/silica and carrageenan/DMMP/vermiculite composite hydrogels have the weakest fire prevention effect at 20 g,which is weaker than that of water.However,the fire prevention effect of carrageenan/DMMP/vermiculite composite hydrogels exceeded that of water at 40 and 60 g.Additionally,the fire prevention effect of the sodium alginate/sepiolite/ammonium polyphosphate composite hydrogel is most significant in common tests,attributed to the intumescent flame retardant system.展开更多
Na-ion batteries are considered a promising next-generation battery alternative to Li-ion batteries,due to the abundant Na resources and low cost.Most efforts focus on developing new materials to enhance energy densit...Na-ion batteries are considered a promising next-generation battery alternative to Li-ion batteries,due to the abundant Na resources and low cost.Most efforts focus on developing new materials to enhance energy density and electrochemical performance to enable it comparable to Li-ion batteries,without considering thermal hazard of Na-ion batteries and comparison with Li-ion batteries.To address this issue,our work comprehensively compares commercial prismatic lithium iron phosphate(LFP) battery,lithium nickel cobalt manganese oxide(NCM523) battery and Na-ion battery of the same size from thermal hazard perspective using Accelerating Rate Calorimeter.The thermal hazard of the three cells is then qualitatively assessed from thermal stability,early warning and thermal runaway severity perspectives by integrating eight characteristic parameters.The Na-ion cell displays comparable thermal stability with LFP while LFP exhibits the lowest thermal runaway hazard and severity.However,the Na-ion cell displays the lowest safety venting temperature and the longest time interval between safety venting and thermal runaway,allowing the generated gas to be released as early as possible and detected in a timely manner,providing sufficient time for early warning.Finally,a database of thermal runaway characteristic temperature for Li-ion and Na-ion cells is collected and processed to delineate four thermal hazard levels for quantitative assessment.Overall,LFP cells exhibit the lowest thermal hazard,followed by the Na-ion cells and NCM523 cells.This work clarifies the thermal hazard discrepancy between the Na-ion cell and prevalent Li-ion cells,providing crucial guidance for development and application of Na-ion cell.展开更多
During the 36th Chinese National Antarctic Research Expedition,aerosol samples were gathered from the Ross Sea in Antarctic to assess the climatic impact of the Australian fires that occurred in 2019-2020.The chemical...During the 36th Chinese National Antarctic Research Expedition,aerosol samples were gathered from the Ross Sea in Antarctic to assess the climatic impact of the Australian fires that occurred in 2019-2020.The chemical compositions,including levoglucosan(Lev)and its isomers,galactosan(Gan)and mannosan(Man),were analyzed.Principal component analysis helped identify the potential sources of these chemical components.By combining backward trajectories with the ratios of CLev/CMan and CMan/CGan,it was further inferred that Australia might be the potential source region for biomass burning.The radiative forcing resulting from biomass burning was evaluated using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART)model,which revealed that black carbon emitted from biomass burning could slightly warm the atmosphere(+0.52 W·m^(-2))while causing slightly cooling at the surface(-0.73 W·m^(-2))and the top of the atmosphere(-0.22 W·m^(-2))over the Ross Sea.展开更多
The future large-scale application of sodium-ion batteries(SIBs)is inseparable from their excellent electrochemical performance and reliable safety characteristics.At present,there are few studies focusing on their sa...The future large-scale application of sodium-ion batteries(SIBs)is inseparable from their excellent electrochemical performance and reliable safety characteristics.At present,there are few studies focusing on their safety performance.The analysis of thermal stability and structural changes within a single material cannot systematically describe the complex interplay of components within the battery system during the thermal runaway process.Furthermore,the reaction between the battery materials themselves and their counterparts within the system can stimulate more intense exothermic behavior,thereby affecting the safety of the entire battery system.Therefore,this study delved into the thermal generation and gas evolution characteristics of the positive electrode(Na_(x)Ni_(1/3)Fe_(1/3)Mn_(1/3)O_(2),NFM111)and the negative electrode(hard carbon,HC)in SIBs,utilizing various material combinations.Through the integration of microscopic and macroscopic characterization techniques,the underlying reaction mechanisms of the positive and negative electrode materials within the battery during the heating process were elucidated.Three important results are derived from this study:(Ⅰ)The instability of the solid electrolyte interphase(SEI)leads to its decomposition at temperatures below 100℃,followed by extensive decomposition within the range of 100-150℃,yielding heat and the formation of inorganic compounds,such as Na_(2)CO_(3)and Na_(2)O;(Ⅱ)The reaction between NFM111 and the electrolyte constitutes the primary exothermic event during thermal abuse,with a discernible reaction also occurring between sodium metal and the electrolyte throughout the heating process;(Ⅲ)The heat production and gas generation behaviors of multi-component reactions do not exhibit complete correlation,and the occurrence of gas production does not necessarily coincide with thermal behavior.The results presented in this study can provide useful guidance for the safety improvement of SIBs.展开更多
In this work,the surface properties of CeO_(2)-supported Cu catalysts were adjusted via doping Mn or/and Co with different ratios(CuMnaCO_(1-a)/Ce,a=0,0.25,0.5,0.75 and 1).The roles of metallic effects on the activiti...In this work,the surface properties of CeO_(2)-supported Cu catalysts were adjusted via doping Mn or/and Co with different ratios(CuMnaCO_(1-a)/Ce,a=0,0.25,0.5,0.75 and 1).The roles of metallic effects on the activities,structures and reaction pathways of the catalysts were investigated using various characterization techniques.The results reveal the CuMnCo/Ce catalysts show better performance,followed by Cu/Ce and MnCo/Ce.Among CuMnCo/Ce catalysts,the CuMn_(0.25)Co_(0.75)/Ce exhibits the excellent activity under a higher gas hourly space velocity.The improved surface properties mainly involve the higher dispersion of CuOxand stronger redox cycle due to Co substitution,and more active oxygen species(oxygen vacancies and activated lattice oxygen)contributed by Mn substitution.From the in situ infrared spectroscopy(in situ IR)experiments,the electron transfer of Cu and Co can strengthen the adsorption of CO on Cu species indirectly,whereas,more oxygen defects coming from the Mn-OV-Ce structure boost the activation of oxygen species,the formation of carbonate intermediates and then the release of CO_(2).This work may guide the simple regulation of active sites and the utilization of the catalytic potential of Cu-Ce oxide catalysts.展开更多
Solid-state battery(SSB)with lithium metal anode(LMA)is considered as one of the most promising storage devices for the next generation.To simultaneously address two critical issues in lithium metal batteries:the nega...Solid-state battery(SSB)with lithium metal anode(LMA)is considered as one of the most promising storage devices for the next generation.To simultaneously address two critical issues in lithium metal batteries:the negative impact of interfacial compatibility on the electrochemical performance and the safety risks associated with Li dendrite growth-we propose a dual in-situ strategy for fabricating SSBs.Herein,the excellent cycling performance and improved safety of polymer SSB under dual in-situ strategy was confirmed.The lower Li nucleation barrier of Sn leads to uniform Li deposition on the modified-Li(ModLi)/solid-state electrolyte(SSE)interface.LiF-enriched layer on LMA contributes to capacity retention of 92%after 550 cycles in LiFePO_(4)SSB.The modified layer provides outstanding dendrite suppression ability under an overcharge condition of 5.5 V.The higher thermal stability of SSE than liquid electrolyte was investigated through in-situ heat and gas generation analysis,with ModLi+SSE generating only 9.9%of Li+SSE.Higher cycling stability of SSB was demonstrated through in-situ cycling heat generation analysis,and lower temperature sensitivity of SSB with 31%of heat production decrease from 30 to 70℃,while LIBs show a 54%reduction.Excellent high-temperature stability was proved by a 92%capacity retention at 60℃after 50 cycles.Ultimately,pouch cells with SSE of higher thermal stability and modifications on LMA achieved a higher self-heating onset temperature(Tonset)of 180℃and a lower thermal runaway maximum temperature(T_(max))of 401℃,The impacts of dual in-situ strategy for materials,interfaces,coin cells and pouch cells aid in further understanding on thermal runaway mechanism of SSB.展开更多
基金National Natural Science Foundation of China (No. 52206180)Fundamental Research Funds for the Central Universities,China (No. WK2320000050)。
文摘The corrosion behavior and life of Sn−3.0Ag−0.5Cu solder joints were investigated through fire smoke exposure experiments within the temperature range of 45−80℃.The nonlinear Wiener process and Arrhenius equation were used to establish the probability distribution function and prediction model of the solder joint’s average life and individual remaining useful life.The results indicate that solder joint resistance shows a nonlinear growth trend with time increasing.After 24 h,the solder joint transforms from spherical to rose-like shapes.Higher temperatures accelerate solder joint failure,and the relationship between failure time and temperature conforms to the Arrhenius equation.The predicted life of the model is in good agreement with experimental results,demonstrating the effectiveness and accuracy of the model.
基金supported by the National Natural Science Foundation of China(No.52204248)the Taishan Scholars Program of Shandong Province(tsqn202408191)。
文摘The high energy density of lithium metal batteries(LMBs)has attracted widespread attention,which is expected to improve the endurance mileage of electric vehicles comparable to fossil fuel-powered vehicles.At present,the main research is focused on developing advanced materials and revealing the indepth electrochemical mechanism of LMBs,while there is a significant lagging behind of attention to the safety evaluation.This review aims to emphasize the fire safety challenges faced by LMBs and summarize advanced strategies for improving intrinsic safety.Firstly,the basic chemical composition and working principle of LMBs were introduced compared with lithium-ion batteries.Moreover,we reviewed the thermal runaway problem of LMBs from the aspects of material activity,interfacial stability triggering conditions,thermal runaway behavior and mechanism,the special thermal runaway characteristics,and new safety challenges of Li-S,Li-O_(2),and the solid-state LMBs were discussed in detail.Based on the analysis of the thermal runaway mechanism,we summarized the advanced strategies,including electrolyte design,interphase film construction,separator,and anode design for improving the intrinsic safety of LMBs.Finally,we proposed the fire safety challenge at the battery level and emphasized the necessity of designing safe materials based on the thermal runaway mechanism.Blocking the thermal coupling reaction and conducting multi-strategy collaborative optimization is the key point to restrain thermal runaway.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.72174189,72001095,and 72304123)。
文摘Pressurized buildings have emerged as a novel architectural solution to alleviate altitude illness in high-altitude regions.Unlike conventional buildings,evacuation from this kind of building has to experience a depressurization time,which results in air expansion and heat absorption,creating a dense fog and impairing sight within the buildings.Evacuation experiments were performed in a pressurized oxygen-supplement compartment to investigate the pedestrian motion properties.Based on the questionnaires,participants reported varying degrees of symptoms such as ear blockage,reduced environmental noise,and dizziness,which had a measurable impact on their mobility.We focus on the evacuation parameters through three basic building components:staircases,pressure transition cabins,and escape windows.As the visibility in the compartment decreases from high to low,the movement patterns of pedestrian shift from triangular to single-file with a significant decline in evacuation efficiency.It is found that there is a linear relationship between evacuation time and the number of evacuees through escape windows.The pressure transition cabin is a crucial evacuation route in emergencies,and evacuation time is recommended as the key metric for assessing its effectiveness.These findings offer valuable insights for emergency evacuation strategies in pressurized buildings.
基金funded by the Science and Technology Project of the State Grid Corporation of China (Exploration study on Fire Extinguishing Technology of Lithium Ion Energy Storage Battery DG71-18-002)。
文摘Currently,the effective and clean suppression of lithium-ion battery(LIB)fires remains a challenge.The present work investigates the use of various inhibitor doses(Xin)of dodecafluoro-2-methylpentan-3-one(C_(6) F_(12)O)in 300 Ah LIBs,and systematically examines the thermal and toxic hazards of the extinguished batteries via real scale combustion and gas analysis.The inhibitor is shown to be completely effective.The inhibition mechanism involves a combination of chemical inhibition and physical cooling.While the chemical inhibition effect tends to saturate with increasing Xin,the physical cooling remains effective at higher inhibitor doses.However,extinguishing the battery fire with a high Xin of C_(6)F_(12)O is found to incur serious toxicity problems.These results are expected to provide a guideline for the design of inhibitor doses for the suppression of LIB fires.
基金the National Natural Science Foundation of China(Nos.51761135113,51911530127 and 51973203)the Fundamental Research Funds for the Central Universities(No.WK2320000043).
文摘The high fire safety of polymer nanocomposites is being pursued by research institutions around the world.In addition to intrinsic flame retardancy strategy,the additive-type flame retardants have attracted increasing attention due to low commercial cost and easy fabrication craft.However,traditional additive-type flame retardants usually need high addition amount to achieve a desirable effect which causes many side-effects on the overall performance of polymer materials,such as deteriorated mechanical property and processability.At present two-dimensional(2D)nanomaterials have also been applied to reduce the fire hazards of polymer(nano)composites with the coupling of barrier function and catalysis as well as carbonization effect.Even though most research work mainly focus on graphene-based flame retardants,more emerging two-dimensional nanomaterials are taking away research attention,due to their complementary and unique properties,mainly including hexagonal boron nitride(h-BN),molybdenum disulfide(MoS2),metal organic frameworks(MOF),carbon nitride(CN),titanium carbide(MXene)and black phosphorene(BP).In this review,except for graphene,the flame retardant mechanism involving different layered nanomaterials are also reviewed.Meanwhile,the functionalization method and flame retardancy effect of different layered nanomaterials are emphatically discussed for offering an effective reference to solve the fire hazards of polymer materials.Moreover,this work objectively evaluates the practical significance of polymer/layered nanomaterials composites for industrial application.
基金supported by National Basic Research Program of China (2012CB719702)
文摘Since serious fire occurred frequently in recent years, fire safety of high-rise building has attracted extensive attention. A National Basic Research Program （973 program） of China has been set up by Ministry of Science and Technology （MOST） of China in 2012 to meet the research requirements of fire safety in high-rise buildings. This paper reviews the current state of art of research on fire dynamics of high-rise buildings, including the up-to-date progress of this project. The following three subjects on fire dynamics of high-rise buildings are addressed in this review： the ejected flame and fire plume behavior over facade out of the compartment window, the flame spread behavior over facade thermal insulation materiMs, and the buoyancy-driven smoke transportation characteristics along long vertical channels in high-rise buildings. Prospective future works are discussed and summarized.
基金This research was supported by National Key Research and Development Project(No.2017YFE0113200)National Natural Science Fund of China(Nos.51403004,U1833113).
文摘Biomass phytic acid has potential flame retardant value as the main form of phosphorus in plant seeds.In this study,phytate-based flame retardants aluminum phytate(PA-Al)and iron phytate(PA-Fe)were synthesized and characterized.Subsequently,they were introduced into rigid polyurethane foam(RPUF)as flame retardants by one-step water-blown method.The results indicated that RPUF/PA-Fe30 exhibited the highest char residue of 22.1 wt%,significantly higher than 12.4 wt%of RPUF.Cone calorimetry analysis showed that the total heat release(THR)of RPUF/PA-Al30 decreased by 17.0%and total smoke release(TSR)decreased by 22.0%compared with pure RPUF,which were the lowest,demonstrating a low fire risk and good smoke suppression.Thermogravimetric analysis-Fourier transform infrared spectrometer(TG-FTIR)implied the release intensity of flammable gases(hydrocarbons,esters)and toxic gases(isocyanate,CO,aromatic compounds,HCN)of composites was significantly reduced after the addition of PA-Fe.The analysis of char residue indicated that the RPUF composites formed a dense char layer with a high degree of graphitization after the addition of PA-Al/PA-Fe,endowing RPUF composites with excellent mass&heat transmission inhibition effect and fire resistance in the combustion process.
基金Project(50706059) supported by the National Natural Science Foundation of ChinaProject(HZ2009-KF05) supported by Open Fund of State Key Laboratory of Fire Science of University of Science and Technology in ChinaProject supported by the Fundamental Research Funds for the Central Universities of China
文摘Experimental research was conducted to study the structural behaviors of a steel roof truss model without fire-proof coating under pool fire conditions. The data of temperature distribution and displacements of typical members were obtained. It is found that the temperature distribution of environment inside the structure, which is found to be in accordance with the multi-zone model with height, has a decisive effect on the tempera^tre evolution of steel members. Besides, it can also be observed that due to the restriction and coordination among the truss members in the localized fire, the maximum relative deflection, which occurs at the mid-span of the top chord, is relatively slight and has not exceeded 1 mm under experimental conditions. On the other hand, the column experiences a notable thermal expansion during the test. Then, a finite element model is presented and validated by the test results.
基金This work was supported by the National Key Research and Development Program of China(2022YFC3003101)the Fundamental Research Funds for the Central Universities(WK2320000050)the Science and Technology Program of State Grid Anhui Electric Power Co.,Ltd.(521205220001).
文摘Forest fire accidents caused by distribution line faults occur frequently,resulting in heavy impacts on people’s safety and social and economic development.Currently,there are few risk assessments for forest fires induced by over-head distribution lines,and existing assessment methods may have difficulties in data acquisition.On this basis,a novel as-sessment framework based on an analytic hierarchy process,a Bayesian network and a Fussel-Vesely importance metric is proposed in this paper.The framework combines field research and historical operation and maintenance data to assess the regional-scale risk of forest fires induced by overhead distribution lines to derive the probability of forest fires and to identify high-risk lines and key hazard events in the assessment region.Finally,taking the southern Anhui region as an ex-ample,the annual fire probability of forest fires induced by overhead distribution lines in the southern Anhui region is 5.88%,and rectification measures are proposed.This study provides management with a complete assessment framework that optimizes the difficulty of data collection and allows for additional targeted corrective measures to be proposed for the entire region and route on the basis of the assessment results.
基金Opening Fund of State Key Laboratory of Fire Science,University of Science and Technology of China(No.HZ2011-KF04)
文摘Water mist technology provides efficient firefighting performance while there is still room for improvement. So varieties of additives have been studied in recent years both at home and abroad. The self-made additives are used to compare the firefighting performance of diesel and heptane fire in open space. By adjusting the concentration of substance in the additives and conducting the experiment under the pressure of 0.3 MPa,0.5 MPa and 0.7 MPa,extinguish time and temperature are measured in the experiment. Through the experiments using different fuels,it can be found when the fuel is heptane that has a lower ignition point and a higher evaporation rate, the water mist additive can still significantly improve the firefighting performance. According to the data based on different concentrations of fluorinated surfactants,we find that fluorinated surfactants are the main substance to improve the performances by changing physical property of water mist. Optimal proportion of the additives for firefighting performance is found by experiment results.
基金Anhui provincial major science and technology project(No.202103c08020005).
文摘Biomolecular self-assembly has lately emerged as an intriguing method for creating stable gas-liquid dis-persions with unique functional characteristics.In this work,protein-metal coordination complexes were designed as the stabilizer for generating ultrastable fire-fighting foam and creating interfacial architec-tures that were actively switched between"rigid"and"mobile"interfacial states of liquid films in re-sponse to changes in pH and bulk solution compositions(metal ions or alkyl polyglycosides).The re-flected light interferometric technique was used to check interfacial states,and the foaming kinetics and rheological response of aqueous solution and liquid foam were investigated by dynamic surface tension tests and oscillatory rheology analysis.The results showed that liquid foams with mobile films with lower yield limits had a faster spreading rate to cover the burning oil,liquid foams with semi-rigid films can-not extinguish fires due to interfacial instability,and the enhanced rheology of the foam with rigid films established a robust and impenetrable barrier to effectively suppress fuel evaporation and combustion.A new correlation between interfacial properties and the fire-fighting performance of foam was proposed,which showed that the fire-extinguishing time of foam could be well correlated by the interfacial states or film lifetime rather than classical thermodynamics entry,spreading,and bridging coefficients(ESB co-efficients).
基金Sponsored by the National Natural Science Foundation of China(Grant No.50676089)
文摘In order to investigate the behavior of external welded flange-bolted web joints of steel structure exposed to fire,a series of experiments were carried out.Influence of fire model and load ratio on the behavior of the joints,failure characteristics and fracture modes of the joints exposed to fire were studied.The experimental results indicated that the fire model has a great influence on the temperature rising as well as temperature distribution of the joints exposed to fire.A slower temperature rising fire will lead to slower temperature rising and more uniform temperature distribution of joint.Decrease of the load ratio will improve the fire-resistant capability of the joint.Furthermore,a highly detailed three-dimensional(3-D) finite element model(FEM) was set up with ANSYS software to predict the behavior of the external welded flange-bolted web joints exposed to fire.Comparisons between the predicted results and the experimental results indicated that FEM has an acceptable degree of accuracy to predict the behavior of this type of joints exposed to fire.
基金the financial supports from Fundamental Research Funds for the Central Universities(2020CDJQY-A006)the National Natural Science Foundation of China(No.51603025)The Opening Fund of State Key Laboratory of Fire Science(HZ2019-KF11).
文摘In this work,a bio-based flame retardant(Cy-HEDP)was synthesized from cytosine and HEDP through a facile salt-forming reaction and embedded into epoxy matrix to improve the flame retardancy and smoke suppression performance.The product Cy-HEDP was well characterized by FTIR,^(1)H and^(31)P NMR and SEM tests.On the basis of the results,by adding 15 wt%Cy-HEDP,the EP15 can pass UL-94 V-0 rating,and the total smoke production(TSP)as well as total heat release(THR)can be decreased by 61.05%(from 22.61 to 8.7 m^(2)/m^(2))and 39.44%(from 103.19 to 62.50 MJ/m^(2))in comparison to the unfilled EP,reflecting the attenuated smoke toxicity and impeded heat generation.According to the analysis results of residual char,it can be concluded that Cy-HEDP possessed the ability to promote the formation of continuous and dense char layers,which would be a physical barrier to insulate oxygen and prevent heat feedback during the combustion of EP.This work provide inspiration towards developing bio-based flame retardant,probably extending the prospects to other polymeric material system.
文摘With rapid economic and social development in China, high-rise buildings have continuously sprung up since 2006. However, several big fire accidents in high-rise buildings such as the Beijing Television Cultural Center fire in 2009 and the Shanghai Jing＇an District fire in 2010 etc. have claimed people＇s lives and caused huge amounts of economic and property losses,
基金the National Key Research and Development Program of China(Grant No.2017YFC0805900)the Fundamental Research Funds for the Central Universities(Grant No.WK2320000047)the USTC Research Funds of the Double First-Class Initiative(Grant No.YD2320002004).
文摘To solve the fire accidents caused by coal combustion,this work prepared four hybrid hydrogel materials using bio-based polymers,flame retardants,and inorganic materials.Compared to pure water and 3.5 wt%MgCl_(2)solution,the as-prepared hydrogel presents good fire prevention performance.In addition,it is found that CO and CO_(2)are not produced by coal when the pyrolysis temperature is lower than 200℃.During low-temperature pyrolysis,CO is more likely to be produced than CO_(2),indicating inadequate pyrolysis behavior.At the same time,the addition of fire-preventing hydrogel can not only decrease the maximum CO_(2)concentration before the critical temperature but also prolong the corresponding time.In addition,based on the cone calorimeter test,the inhibition effects of pure water,magnesium chloride solution,and four hybrid hydrogels on heat release behavior are evaluated.It is demonstrated that different dosages of different hydrogels affected the fire prevention effect.Phosphorous-modified cellulose/silica and carrageenan/DMMP/vermiculite composite hydrogels have the weakest fire prevention effect at 20 g,which is weaker than that of water.However,the fire prevention effect of carrageenan/DMMP/vermiculite composite hydrogels exceeded that of water at 40 and 60 g.Additionally,the fire prevention effect of the sodium alginate/sepiolite/ammonium polyphosphate composite hydrogel is most significant in common tests,attributed to the intumescent flame retardant system.
基金supported by the National Key R&D Program of China(No.2022YFE0207400)supported by the Xiaomi Young Talents Programsupported by the Youth Innovation Promotion Association CAS(No.Y201768)。
文摘Na-ion batteries are considered a promising next-generation battery alternative to Li-ion batteries,due to the abundant Na resources and low cost.Most efforts focus on developing new materials to enhance energy density and electrochemical performance to enable it comparable to Li-ion batteries,without considering thermal hazard of Na-ion batteries and comparison with Li-ion batteries.To address this issue,our work comprehensively compares commercial prismatic lithium iron phosphate(LFP) battery,lithium nickel cobalt manganese oxide(NCM523) battery and Na-ion battery of the same size from thermal hazard perspective using Accelerating Rate Calorimeter.The thermal hazard of the three cells is then qualitatively assessed from thermal stability,early warning and thermal runaway severity perspectives by integrating eight characteristic parameters.The Na-ion cell displays comparable thermal stability with LFP while LFP exhibits the lowest thermal runaway hazard and severity.However,the Na-ion cell displays the lowest safety venting temperature and the longest time interval between safety venting and thermal runaway,allowing the generated gas to be released as early as possible and detected in a timely manner,providing sufficient time for early warning.Finally,a database of thermal runaway characteristic temperature for Li-ion and Na-ion cells is collected and processed to delineate four thermal hazard levels for quantitative assessment.Overall,LFP cells exhibit the lowest thermal hazard,followed by the Na-ion cells and NCM523 cells.This work clarifies the thermal hazard discrepancy between the Na-ion cell and prevalent Li-ion cells,providing crucial guidance for development and application of Na-ion cell.
基金supported by the National Natural Science Foundation of China (Grant nos. 41941014 and 41930532)financially supported by National Polar Special Program “Impact and Response of Antarctic Seas to Climate Change”(Grant no. IRASCC 01-01-02E)。
文摘During the 36th Chinese National Antarctic Research Expedition,aerosol samples were gathered from the Ross Sea in Antarctic to assess the climatic impact of the Australian fires that occurred in 2019-2020.The chemical compositions,including levoglucosan(Lev)and its isomers,galactosan(Gan)and mannosan(Man),were analyzed.Principal component analysis helped identify the potential sources of these chemical components.By combining backward trajectories with the ratios of CLev/CMan and CMan/CGan,it was further inferred that Australia might be the potential source region for biomass burning.The radiative forcing resulting from biomass burning was evaluated using the Santa Barbara DISORT Atmospheric Radiative Transfer(SBDART)model,which revealed that black carbon emitted from biomass burning could slightly warm the atmosphere(+0.52 W·m^(-2))while causing slightly cooling at the surface(-0.73 W·m^(-2))and the top of the atmosphere(-0.22 W·m^(-2))over the Ross Sea.
基金supported by the National Natural Science Foundation of China(52404259)supported by Youth Innovation Promotion Association CAS(Y201768)。
文摘The future large-scale application of sodium-ion batteries(SIBs)is inseparable from their excellent electrochemical performance and reliable safety characteristics.At present,there are few studies focusing on their safety performance.The analysis of thermal stability and structural changes within a single material cannot systematically describe the complex interplay of components within the battery system during the thermal runaway process.Furthermore,the reaction between the battery materials themselves and their counterparts within the system can stimulate more intense exothermic behavior,thereby affecting the safety of the entire battery system.Therefore,this study delved into the thermal generation and gas evolution characteristics of the positive electrode(Na_(x)Ni_(1/3)Fe_(1/3)Mn_(1/3)O_(2),NFM111)and the negative electrode(hard carbon,HC)in SIBs,utilizing various material combinations.Through the integration of microscopic and macroscopic characterization techniques,the underlying reaction mechanisms of the positive and negative electrode materials within the battery during the heating process were elucidated.Three important results are derived from this study:(Ⅰ)The instability of the solid electrolyte interphase(SEI)leads to its decomposition at temperatures below 100℃,followed by extensive decomposition within the range of 100-150℃,yielding heat and the formation of inorganic compounds,such as Na_(2)CO_(3)and Na_(2)O;(Ⅱ)The reaction between NFM111 and the electrolyte constitutes the primary exothermic event during thermal abuse,with a discernible reaction also occurring between sodium metal and the electrolyte throughout the heating process;(Ⅲ)The heat production and gas generation behaviors of multi-component reactions do not exhibit complete correlation,and the occurrence of gas production does not necessarily coincide with thermal behavior.The results presented in this study can provide useful guidance for the safety improvement of SIBs.
基金Project supported by the National Natural Science Foundation of China(52206180)。
文摘In this work,the surface properties of CeO_(2)-supported Cu catalysts were adjusted via doping Mn or/and Co with different ratios(CuMnaCO_(1-a)/Ce,a=0,0.25,0.5,0.75 and 1).The roles of metallic effects on the activities,structures and reaction pathways of the catalysts were investigated using various characterization techniques.The results reveal the CuMnCo/Ce catalysts show better performance,followed by Cu/Ce and MnCo/Ce.Among CuMnCo/Ce catalysts,the CuMn_(0.25)Co_(0.75)/Ce exhibits the excellent activity under a higher gas hourly space velocity.The improved surface properties mainly involve the higher dispersion of CuOxand stronger redox cycle due to Co substitution,and more active oxygen species(oxygen vacancies and activated lattice oxygen)contributed by Mn substitution.From the in situ infrared spectroscopy(in situ IR)experiments,the electron transfer of Cu and Co can strengthen the adsorption of CO on Cu species indirectly,whereas,more oxygen defects coming from the Mn-OV-Ce structure boost the activation of oxygen species,the formation of carbonate intermediates and then the release of CO_(2).This work may guide the simple regulation of active sites and the utilization of the catalytic potential of Cu-Ce oxide catalysts.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2024B1111080001)the National Natural Science Foundation of China(52204248 and 52474258)Youth Innovation Promotion Association CAS(Y201768)。
文摘Solid-state battery(SSB)with lithium metal anode(LMA)is considered as one of the most promising storage devices for the next generation.To simultaneously address two critical issues in lithium metal batteries:the negative impact of interfacial compatibility on the electrochemical performance and the safety risks associated with Li dendrite growth-we propose a dual in-situ strategy for fabricating SSBs.Herein,the excellent cycling performance and improved safety of polymer SSB under dual in-situ strategy was confirmed.The lower Li nucleation barrier of Sn leads to uniform Li deposition on the modified-Li(ModLi)/solid-state electrolyte(SSE)interface.LiF-enriched layer on LMA contributes to capacity retention of 92%after 550 cycles in LiFePO_(4)SSB.The modified layer provides outstanding dendrite suppression ability under an overcharge condition of 5.5 V.The higher thermal stability of SSE than liquid electrolyte was investigated through in-situ heat and gas generation analysis,with ModLi+SSE generating only 9.9%of Li+SSE.Higher cycling stability of SSB was demonstrated through in-situ cycling heat generation analysis,and lower temperature sensitivity of SSB with 31%of heat production decrease from 30 to 70℃,while LIBs show a 54%reduction.Excellent high-temperature stability was proved by a 92%capacity retention at 60℃after 50 cycles.Ultimately,pouch cells with SSE of higher thermal stability and modifications on LMA achieved a higher self-heating onset temperature(Tonset)of 180℃and a lower thermal runaway maximum temperature(T_(max))of 401℃,The impacts of dual in-situ strategy for materials,interfaces,coin cells and pouch cells aid in further understanding on thermal runaway mechanism of SSB.
