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
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
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
Fluorinated electrolytes possess good antioxidant capacity that provides high compatibility to high-voltage cathode and flame retardance;thus,they are considered as a promising solution for advanced lithium-ion batter...Fluorinated electrolytes possess good antioxidant capacity that provides high compatibility to high-voltage cathode and flame retardance;thus,they are considered as a promising solution for advanced lithium-ion batteries carrying both high-energy density and high safety.Moreover,the fluorinated electrolytes are widely used to form stable electrolyte interphase,due to their chemical reactivity with lithiated graphite or lithium.However,the influence of this reactivity on the thermal safety of batteries is seldom discussed.Herein,we demonstrate that the flame-retardant fluorinated electrolytes help to reduce the flammability,while the lithium-ion batteries with flame-retardant fluorinated electrolytes still undergo thermal runaway and disclose their different thermal runaway pathway from that of battery with conventional electrolyte.The reduction in fluorinated components(e.g.,LiPF 6 and fluoroethylene carbonate(FEC))by fully lithiated graphite accounts for a significant heat release during battery thermal runaway.The 13%of total heat is sufficient to trigger the chain reactions during battery thermal runaway.This study deepens the understanding of the thermal runaway mechanism of lithium-ion batteries employing flame-retardant fluorinated electrolytes,providing guidance on the concept of electrolyte design for safer lithium-ion batteries.展开更多
Lithium-ion batteries with high-energy density are extensively commercialized in long-range electric vehicles. However, they are poor in thermal stability and pose fire or explosion, which has attracted the global att...Lithium-ion batteries with high-energy density are extensively commercialized in long-range electric vehicles. However, they are poor in thermal stability and pose fire or explosion, which has attracted the global attention. This study describes a new route to mitigate the battery thermal runaway(TR) hazard by poison agents. First, the self-destructive cell is built using the embedded poison layer. Then, the poisoning mechanism and paths are experimentally investigated at the material, electrode, and cell levels. Finally, the proposed route is verified by TR tests. The results show the TR hazard can be significantly reduced in the self-destructive cell based on a new reaction sequence regulation. Specifically, the maximum temperature of the self-destructive cell is more than 300℃ lower than that of the normal cell during TR. The drop in maximum temperature can reduce total heat release and the probability of TR propagation in the battery system, significantly improving battery safety.展开更多
Structurally compact battery packs significantly improve the driving range of electric vehicles.Technologies like Cell-to-Pack increase energy density by 15%-20%.However,the safety implications of multiple tightly-pac...Structurally compact battery packs significantly improve the driving range of electric vehicles.Technologies like Cell-to-Pack increase energy density by 15%-20%.However,the safety implications of multiple tightly-packed battery cells still require in-depth research.This paper studies thermal runaway propagation behavior in a Cell-to-Pack system and assesses propagation speed relative to other systems.The investigation includes temperature response,extent of battery damage,pack structure deformation,chemical analysis of debris,and other considerations.Results suggest three typical patterns for the thermal runaway propagation process:ordered,disordered,and synchronous.The synchronous propagation pattern displayed the most severe damage,indicating energy release is the largest under the synchronous pattern.This study identifies battery deformation patterns,chemical characteristics of debris,and other observed factors that can both be applied to identify the cause of thermal runaway during accident investigations and help promote safer designs of large battery packs used in large-scale electric energy storage systems.展开更多
Sodium-ion batteries are expected to be more affordable for stationary applications than lithium-ion batteries,while still offering sufficient energy density and operational capacity to power a significant segment of ...Sodium-ion batteries are expected to be more affordable for stationary applications than lithium-ion batteries,while still offering sufficient energy density and operational capacity to power a significant segment of the battery market.Despite this,thermal runaway explosions associated with organic electrolytes have led to concerns regarding the safety of sodium-ion batteries.Among electrolytes,ionic liquids are promising because they have negligible vapor pressure and show high thermal and electrochemical stability.This review discusses the safety contributions of these electrolyte properties for high-temperature applications.The ionic liquids provide thermal stability while at the same time promoting high-voltage window battery operations.Moreover,apart from cycle stability,there is an additional safety feature attributed to modified ultra-concentrated ionic liquid electrolytes.Concerning these contributions,the following have been discussed,heat sources and thermal runaway mechanisms,thermal stability,the electrochemical decomposition mechanism of stable cations,and the ionic transport mechanism of ultra-concentrated ionic liquid electrolytes.In addition,the contributions of hybrid electrolyte systems consisting of ionic liquids with either organic carbonate or polymers are also discussed.The thermal stability of ionic liquids is found to be the main contributor to cell safety and cycle stability.For high-temperature applications where electrolyte safety,capacity,and cycle stability are important,highly concentrated ionic liquid electrolyte systems are potential solutions for sodium-ion battery applications.展开更多
Lithium-ion batteries are widely used in electric vehicles and electronics, and their thermal safety receives widespread attention from consumers. In our study, thermal runaway testing was conducted on the thermal sta...Lithium-ion batteries are widely used in electric vehicles and electronics, and their thermal safety receives widespread attention from consumers. In our study, thermal runaway testing was conducted on the thermal stability of commercial lithium-ion batteries, and the internal structure of the battery was analyzed with an in-depth focus on the key factors of the thermal runaway. Through the study of the structure and thermal stability of the cathode, anode, and separator, the results showed that the phase transition reaction of the separator was the key factor affecting the thermal runaway of the battery for the condition of a low state of charge.展开更多
Thermal runaway caused by overcharging results in catastrophic disasters. The influences of charging rate, ambient temperature and aging on thermal runaway caused by overcharging are studied qualitatively and quantita...Thermal runaway caused by overcharging results in catastrophic disasters. The influences of charging rate, ambient temperature and aging on thermal runaway caused by overcharging are studied qualitatively and quantitatively in this manuscript. The results of overcharging tests indicate that high charging rate and ambient temperature increase thermal runaway risk. Aging in 40 ℃ decreases thermal runaway risk. The risk increase of battery with high overcharging rate and in high ambient temperature is due to fast lithium plating reaction and accelerated SEI decomposition, respectively. The risk decrease of aged battery is due to the occurrence of SEI before overcharging tests. SEI suppresses the side reactions between lithium plating and electrolyte. The results of orthogonal tests indicate that the rank of effect is: discharging rate > ambient temperature > aging. The heat generation is calculated based on the results of overcharging tests. The calculation results indicate that heat generated by side reactions contributes more to the total heat generation. Although thermal runaway does not occur during overcharging with low current, the heat dissipation of the lithium-ion battery is the most and deserves focus. The results are important to the design of battery management system and thermal management system to prevent thermal runaway induced by overcharging in total lifespan of battery.展开更多
This study examines the thermal runaway of a lithium ion battery caused by poor heat dissipation performances.The heat transfer process is analyzed on the basis of standard theoretical concepts.Water mist additives ar...This study examines the thermal runaway of a lithium ion battery caused by poor heat dissipation performances.The heat transfer process is analyzed on the basis of standard theoretical concepts.Water mist additives are considered as a tool to suppress the thermal runaway process.The ensuing behaviour of the battery in terms of surface temperature and heat generation is analyzed for different charge and discharge rates.It is found that when the remaining charge is 100%,the heat generation rate of the battery is the lowest,and the surface temperature with a 2C charge rate is higher than that obtained for a 0.5C charge rate.The experimental results show that when the additive concentration is 20%NaCl,its ability to inhibit the thermal runaway is the strongest.展开更多
LiFePO_(4)(LFP)lithium-ion batteries have gained widespread use in electric vehicles due to their safety and longevity,but thermal runaway(TR)incidents still have been reported.This paper explores the TR characteristi...LiFePO_(4)(LFP)lithium-ion batteries have gained widespread use in electric vehicles due to their safety and longevity,but thermal runaway(TR)incidents still have been reported.This paper explores the TR characteristics and modeling of LFP batteries at different states of charge(SOC).Adiabatic tests reveal that TR severity increases with SOC,and five stages are identified based on battery temperature evolution.Reaction kinetics parameters of exothermic reactions in each TR stage are extracted,and TR models for LFP batteries are established.The models accurately simulate TR behaviors at different SOCs,and the simulated TR characteristic temperatures also agree well with the experimental results,with errors of TR characteristic temperatures less than 3%.The prediction errors of TR characteristic temperatures under oven test conditions are also less than 1%.The results provide a comprehensive understanding of TR in LFP batteries,which is useful for battery safety design and optimization.展开更多
Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the o...Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the origins for the thermal runaway of 1.0 Ah cycled Li-S pouch cells.16-cycle pouch cell indicates high safety,heating from 30 to 300 ℃ without thermal runaway,while 16-cycle pouch cell with additional electrolyte undergoes severe thermal runaway at 147.9 ℃,demonstrating the key roles of the electrolyte on the thermal safety of batteries.On the contrary,thermal runaway does not occur for 45-cycle pouch cell despite the addition of the electrolyte.It is found that the higher-order polysulfides(Li_(2)S_(x) ≥ 6)are discovered in 16-cycle electrolyte while the sulfur species in 45-cycle electrolyte are Li_(2)S_(x) ≤ 4.In addition,strong exothermic reactions are discovered between cycled Li and dissolved higher-order polysulfide(Li_(2)S_(6) and Li_(2)S_(8))at 153.0 ℃,driving the thermal runaway of cycled Li-S pouch cells.This work uncovers the potential safety risks of Li-S batteries and negative roles of the polysulfide shuttle for Li-S batteries from the safety view.展开更多
Thermal runaway(TR)is a critical issue hindering the large-scale application of lithium-ion batteries(LIBs).Understanding the thermal safety behavior of LIBs at the cell and module level under different state of charg...Thermal runaway(TR)is a critical issue hindering the large-scale application of lithium-ion batteries(LIBs).Understanding the thermal safety behavior of LIBs at the cell and module level under different state of charges(SOCs)has significant implications for reinforcing the thermal safety design of the lithium-ion battery module.This study first investigates the thermal safety boundary(TSB)correspondence at the cells and modules level under the guidance of a newly proposed concept,safe electric quantity boundary(SEQB).A reasonable thermal runaway propagation(TRP)judgment indicator,peak heat transfer power(PHTP),is proposed to predict whether TRP occurs.Moreover,a validated 3D model is used to quantitatively clarify the TSB at different SOCs from the perspective of PHTP,TR trigger temperature,SOC,and the full cycle life.Besides,three different TRP transfer modes are discovered.The interconversion relationship of three different TRP modes is investigated from the perspective of PHTP.This paper explores the TSB of LIBs under different SOCs at both cell and module levels for the first time,which has great significance in guiding the thermal safety design of battery systems.展开更多
Safe batteries are the basis for next-generation application scenarios such as portable energy storage devices and electric vehicles,which are crucial to achieving carbon neutralization.Electrolytes,separators,and ele...Safe batteries are the basis for next-generation application scenarios such as portable energy storage devices and electric vehicles,which are crucial to achieving carbon neutralization.Electrolytes,separators,and electrodes as main components of lithium batteries strongly affect the occurrence of safety accidents.Responsive materials,which can respond to external stimuli or environmental change,have triggered extensive attentions recently,holding great promise in facilitating safe and smart batteries.This review thoroughly discusses recent advances regarding the construction of high-safety lithium batteries based on internal thermal-responsive strategies,together with the corresponding changes in electrochemical performance under external stimulus.Furthermore,the existing challenges and outlook for the design of safe batteries are presented,creating valuable insights and proposing directions for the practical implementation of safe lithium batteries.展开更多
The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials.However,the impact of the above coupling on thermal hazard assessment is not considered in the literat...The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials.However,the impact of the above coupling on thermal hazard assessment is not considered in the literature studies.In this work,nitroguanidine(NQ)and 1,3,5-trinitro-1,3,5-triazine(RDX)are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical materials.The linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal analyser.The thermal decomposition curves are decoupled by advanced thermokinetics software.The thermal decomposition and kinetic parameters before and after decoupling are calculated.The results of TG experiment show that both NQ and RDX began to lose mass during the endothermic stage.The endothermic melting and exothermic decomposition of NQ and RDX are coupled within this stage.The coupling effect has different degrees of influence on its initial decomposition temperature and safety parameters.Compared with the parameters in the coupling state,the initial decomposition temperature and adiabatic induction period after decoupling decrease.The self-accelerating decomposition temperature increases,and internal thermal runaway time decreases.In the thermal hazard assessment of chemical materials with coupling effects,the calculated parameters after decoupling should be taken as an important safety index。展开更多
Thermal illusion aims to create fake thermal signals or hide the thermal target from the background thermal field to mislead infrared observers,and illusion thermotics was proposed to regulate heat flux with artificia...Thermal illusion aims to create fake thermal signals or hide the thermal target from the background thermal field to mislead infrared observers,and illusion thermotics was proposed to regulate heat flux with artificially structured metamaterials for thermal illusion.Most theoretical and experimental works on illusion thermotics focus on two-dimensional materials,while heat transfer in real three-dimensional(3D)objects remains elusive,so the general 3D illusion thermotics is urgently demanded.In this study,we propose a general method to design 3D thermal illusion metamaterials with varying illusions at different sizes and positions.To validate the generality of the 3D method for thermal illusion metamaterials,we realize thermal functionalities of thermal shifting,splitting,trapping,amplifying and compressing.In addition,we propose a special way to simplify the design method under the condition that the size of illusion target is equal to the size of original heat source.The 3D thermal illusion metamaterial paves a general way for illusion thermotics and triggers the exploration of illusion metamaterials for more functionalities and applications.展开更多
Highly thermally conductive graphitic film(GF)materials have become a competitive solution for the thermal management of high-power electronic devices.However,their catastrophic structural failure under extreme altern...Highly thermally conductive graphitic film(GF)materials have become a competitive solution for the thermal management of high-power electronic devices.However,their catastrophic structural failure under extreme alternating thermal/cold shock poses a significant challenge to reliability and safety.Here,we present the first investigation into the structural failure mechanism of GF during cyclic liquid nitrogen shocks(LNS),which reveals a bubbling process characterized by“permeation-diffusion-deformation”phenomenon.To overcome this long-standing structural weakness,a novel metal-nanoarmor strategy is proposed to construct a Cu-modified graphitic film(GF@Cu)with seamless heterointerface.This well-designed interface ensures superior structural stability for GF@Cu after hundreds of LNS cycles from 77 to 300 K.Moreover,GF@Cu maintains high thermal conductivity up to 1088 W m^(−1)K^(−1)with degradation of less than 5%even after 150 LNS cycles,superior to that of pure GF(50%degradation).Our work not only offers an opportunity to improve the robustness of graphitic films by the rational structural design but also facilitates the applications of thermally conductive carbon-based materials for future extreme thermal management in complex aerospace electronics.展开更多
The temperature is one of the principal controlling parameters of oncological hyperthermia. However, local heating forms a complicated thermal distribution in space and has developed over time, too. The decisional fac...The temperature is one of the principal controlling parameters of oncological hyperthermia. However, local heating forms a complicated thermal distribution in space and has developed over time, too. The decisional factors are the heterogeneity of the targeted volume, the electrolyte perfusions controlled by thermal homeostasis, and the spreading of the heat energy with time. A further complication is that the energy absorption sharply changes by depth, so the spatiotemporal development of the temperature distribution requires specialized methods to control. Most of the temperature imaging facilities (thermography, radiometry, electric impedance tomography, etc.) are less precise than the medical practice needs. In contrast, precise point sensing (like thermocouples, thermistors, and fluoroptical methods) is invasive and measures only a discrete point in the robustly changing thermal map. The two most precise thermal imaging methods, computer tomography, and magnetic resonance are expensive and have numerous technical complications. Our objective is to show the complexity of the temperature distribution inside the human body, and offer a relatively simple and cheap method to visualize its spatiotemporal development. A novel emerging technology, the application of ultrasound microbubble contrast agents is a promising method for solving complicated tasks of thermal distribution deep inside the living body. Noteworthy, the temperature distribution does not determine the full hyperthermia process, nonthermal effects make considerable impact, too. Additionally to the difficulties to measure the thermal heterogeneity during hyperthermia in oncology, numerous nonthermal processes, molecular and structural changes are triggered by the incoming electromagnetic energy, which presently has no spatiotemporal visualization technique. Microbubble imaging has a suitable spatiotemporal thermal resolution, and also it is sensitive to nonthermal effects. Its application for characterization of the modulated electrohyperthermia (mEHT) may open a new theranostic facility, using the synergy of the thermal and nonthermal effects of the radiofrequency delivered energy. This complex approach gives facility to follow the mEHT processes, and the proposed microbubble ultrasound imaging has a particularly promising advantage sensing and acting also nonthermally, having potential to characterize the thermally conditioned nonthermal electromagnetic effects in oncologic hyperthermia. The mEHT combined with microbubble ultrasound images could be a robust theranostic method against cancer.展开更多
In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relat...In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relationship and functions of the integrated database,the intelligent thermal control system and the efficient liquid cooling system in the ATMS are elaborated upon.For the complex thermal field regulation system and extreme space thermal environment,a modular simulation and thermal field planning method are proposed,and the feasibility of the planning algorithm is verified by numerical simulation.A solar array liquid cooling system is developed,and the system simulation results indicate that the temperatures of the solar arrays meet the requirements as the spacecraft flies by perihelion and aphelion.The advanced thermal management study supports the development of the SCOPE program and provides a reference for the thermal management in other deep-space exploration programs.展开更多
Underground Thermal Energy Storage(UTES)store unstable and non-continuous energy underground,releasing stable heat energy on demand.This effectively improve energy utilization and optimize energy allocation.As UTES te...Underground Thermal Energy Storage(UTES)store unstable and non-continuous energy underground,releasing stable heat energy on demand.This effectively improve energy utilization and optimize energy allocation.As UTES technology advances,accommodating greater depth,higher temperature and multi-energy complementarity,new research challenges emerge.This paper comprehensively provides a systematic summary of the current research status of UTES.It categorized different types of UTES systems,analyzes the applicability of key technologies of UTES,and evaluate their economic and environmental benefits.Moreover,this paper identifies existing issues with UTES,such as injection blockage,wellbore scaling and corrosion,seepage and heat transfer in cracks,etc.It suggests deepening the research on blockage formation mechanism and plugging prevention technology,improving the study of anticorrosive materials and water treatment technology,and enhancing the investigation of reservoir fracture network characterization technology and seepage heat transfer.These recommendations serve as valuable references for promoting the high-quality development of UTES.展开更多
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 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This work is funded by National Natural Science Foundation of China(Grant No.52006115)Ministry of Science and Technology of China(Grant No.2019YFE0100200)+3 种基金National Natural Science Foundation of China(Grant No.52076121)China National Postdoctoral Program for Innovative Talents(Grant No.BX20190162)China Postdoctoral Science Foundation(Grant No.2019M660631)the Tsinghua University Initiative Scientific Research Program(Grant No.2019Z02UTY06).
文摘Fluorinated electrolytes possess good antioxidant capacity that provides high compatibility to high-voltage cathode and flame retardance;thus,they are considered as a promising solution for advanced lithium-ion batteries carrying both high-energy density and high safety.Moreover,the fluorinated electrolytes are widely used to form stable electrolyte interphase,due to their chemical reactivity with lithiated graphite or lithium.However,the influence of this reactivity on the thermal safety of batteries is seldom discussed.Herein,we demonstrate that the flame-retardant fluorinated electrolytes help to reduce the flammability,while the lithium-ion batteries with flame-retardant fluorinated electrolytes still undergo thermal runaway and disclose their different thermal runaway pathway from that of battery with conventional electrolyte.The reduction in fluorinated components(e.g.,LiPF 6 and fluoroethylene carbonate(FEC))by fully lithiated graphite accounts for a significant heat release during battery thermal runaway.The 13%of total heat is sufficient to trigger the chain reactions during battery thermal runaway.This study deepens the understanding of the thermal runaway mechanism of lithium-ion batteries employing flame-retardant fluorinated electrolytes,providing guidance on the concept of electrolyte design for safer lithium-ion batteries.
基金supported by the National Natural Science Foundation of China (52076121, 51977131, and 51877138)the Natural Science Foundation of Shanghai (19ZR1435800)+1 种基金the State Key Lab-oratory of Automotive Safety and Energy under Project No. KF2020the Shanghai Science and Technology Development Fund(19QA1406200)。
文摘Lithium-ion batteries with high-energy density are extensively commercialized in long-range electric vehicles. However, they are poor in thermal stability and pose fire or explosion, which has attracted the global attention. This study describes a new route to mitigate the battery thermal runaway(TR) hazard by poison agents. First, the self-destructive cell is built using the embedded poison layer. Then, the poisoning mechanism and paths are experimentally investigated at the material, electrode, and cell levels. Finally, the proposed route is verified by TR tests. The results show the TR hazard can be significantly reduced in the self-destructive cell based on a new reaction sequence regulation. Specifically, the maximum temperature of the self-destructive cell is more than 300℃ lower than that of the normal cell during TR. The drop in maximum temperature can reduce total heat release and the probability of TR propagation in the battery system, significantly improving battery safety.
基金supported by the Natural Science Foundation of Hebei Province (B2021507001)the National Natural Science Foundation of China (52106284, 52076121)+2 种基金the Ministry of Science and Technology (2022YFE0207900)the support of the Science and Technology Project of Langfang (2021011017)the Project to Promote Innovation in Doctoral Research at CPPU (BSKY202302)。
文摘Structurally compact battery packs significantly improve the driving range of electric vehicles.Technologies like Cell-to-Pack increase energy density by 15%-20%.However,the safety implications of multiple tightly-packed battery cells still require in-depth research.This paper studies thermal runaway propagation behavior in a Cell-to-Pack system and assesses propagation speed relative to other systems.The investigation includes temperature response,extent of battery damage,pack structure deformation,chemical analysis of debris,and other considerations.Results suggest three typical patterns for the thermal runaway propagation process:ordered,disordered,and synchronous.The synchronous propagation pattern displayed the most severe damage,indicating energy release is the largest under the synchronous pattern.This study identifies battery deformation patterns,chemical characteristics of debris,and other observed factors that can both be applied to identify the cause of thermal runaway during accident investigations and help promote safer designs of large battery packs used in large-scale electric energy storage systems.
基金funded by CUA bursary,Ireland a project titled:Fabrication of solid-state electrolytes for batteries in smartphones and electric vehicles (EVs)。
文摘Sodium-ion batteries are expected to be more affordable for stationary applications than lithium-ion batteries,while still offering sufficient energy density and operational capacity to power a significant segment of the battery market.Despite this,thermal runaway explosions associated with organic electrolytes have led to concerns regarding the safety of sodium-ion batteries.Among electrolytes,ionic liquids are promising because they have negligible vapor pressure and show high thermal and electrochemical stability.This review discusses the safety contributions of these electrolyte properties for high-temperature applications.The ionic liquids provide thermal stability while at the same time promoting high-voltage window battery operations.Moreover,apart from cycle stability,there is an additional safety feature attributed to modified ultra-concentrated ionic liquid electrolytes.Concerning these contributions,the following have been discussed,heat sources and thermal runaway mechanisms,thermal stability,the electrochemical decomposition mechanism of stable cations,and the ionic transport mechanism of ultra-concentrated ionic liquid electrolytes.In addition,the contributions of hybrid electrolyte systems consisting of ionic liquids with either organic carbonate or polymers are also discussed.The thermal stability of ionic liquids is found to be the main contributor to cell safety and cycle stability.For high-temperature applications where electrolyte safety,capacity,and cycle stability are important,highly concentrated ionic liquid electrolyte systems are potential solutions for sodium-ion battery applications.
基金financial supports from National Key R&D Program of China (2018YFC1902200)the key technologies R&D program of Tianjin (18YFZCGX00240)key R&D Program of China Automotive Technology and Research Center Co., Ltd. (18200116)。
文摘Lithium-ion batteries are widely used in electric vehicles and electronics, and their thermal safety receives widespread attention from consumers. In our study, thermal runaway testing was conducted on the thermal stability of commercial lithium-ion batteries, and the internal structure of the battery was analyzed with an in-depth focus on the key factors of the thermal runaway. Through the study of the structure and thermal stability of the cathode, anode, and separator, the results showed that the phase transition reaction of the separator was the key factor affecting the thermal runaway of the battery for the condition of a low state of charge.
基金the support given by National Natural Science Foundation of China(51874184)the Key Natural Science Foundation in Jiangsu Province(18KJA620003)Jiangsu Project Plan for Outstanding Talents Team in Six Research Fields(TD-XNYQC-002)。
文摘Thermal runaway caused by overcharging results in catastrophic disasters. The influences of charging rate, ambient temperature and aging on thermal runaway caused by overcharging are studied qualitatively and quantitatively in this manuscript. The results of overcharging tests indicate that high charging rate and ambient temperature increase thermal runaway risk. Aging in 40 ℃ decreases thermal runaway risk. The risk increase of battery with high overcharging rate and in high ambient temperature is due to fast lithium plating reaction and accelerated SEI decomposition, respectively. The risk decrease of aged battery is due to the occurrence of SEI before overcharging tests. SEI suppresses the side reactions between lithium plating and electrolyte. The results of orthogonal tests indicate that the rank of effect is: discharging rate > ambient temperature > aging. The heat generation is calculated based on the results of overcharging tests. The calculation results indicate that heat generated by side reactions contributes more to the total heat generation. Although thermal runaway does not occur during overcharging with low current, the heat dissipation of the lithium-ion battery is the most and deserves focus. The results are important to the design of battery management system and thermal management system to prevent thermal runaway induced by overcharging in total lifespan of battery.
文摘This study examines the thermal runaway of a lithium ion battery caused by poor heat dissipation performances.The heat transfer process is analyzed on the basis of standard theoretical concepts.Water mist additives are considered as a tool to suppress the thermal runaway process.The ensuing behaviour of the battery in terms of surface temperature and heat generation is analyzed for different charge and discharge rates.It is found that when the remaining charge is 100%,the heat generation rate of the battery is the lowest,and the surface temperature with a 2C charge rate is higher than that obtained for a 0.5C charge rate.The experimental results show that when the additive concentration is 20%NaCl,its ability to inhibit the thermal runaway is the strongest.
基金supported by the Key-Area Research and Development Program of Guangdong Province(2020B0909030001)the National Natural Science Foundation of China(52007099,52076121 and 52177217)+1 种基金China Postdoctoral Science Foundation(2020M680550)support from Young Elite Scientists Sponsorship Program by CAST[No.YESS20220063].
文摘LiFePO_(4)(LFP)lithium-ion batteries have gained widespread use in electric vehicles due to their safety and longevity,but thermal runaway(TR)incidents still have been reported.This paper explores the TR characteristics and modeling of LFP batteries at different states of charge(SOC).Adiabatic tests reveal that TR severity increases with SOC,and five stages are identified based on battery temperature evolution.Reaction kinetics parameters of exothermic reactions in each TR stage are extracted,and TR models for LFP batteries are established.The models accurately simulate TR behaviors at different SOCs,and the simulated TR characteristic temperatures also agree well with the experimental results,with errors of TR characteristic temperatures less than 3%.The prediction errors of TR characteristic temperatures under oven test conditions are also less than 1%.The results provide a comprehensive understanding of TR in LFP batteries,which is useful for battery safety design and optimization.
基金supported by the National Key Research and Development Program(grant No.2021YFB2500300)National Natural Science Foundation of China(grant Nos.22179070,22075029,U1932220)+2 种基金Beijing Municipal Natural Science Foundation(grant No.Z200011)the Natural Science Foundation of Jiangsu Province(grant No.BK20220073)the Fundamental Research Funds for the Central Universities(grant No.2242022R10082).
文摘Comprehensive analyses on thermal runaway mechanisms are critically vital to achieve the safe lithium-sulfur(Li-S)batteries.The reactions between dissolved higher-order polysulfides and Li metal were found to be the origins for the thermal runaway of 1.0 Ah cycled Li-S pouch cells.16-cycle pouch cell indicates high safety,heating from 30 to 300 ℃ without thermal runaway,while 16-cycle pouch cell with additional electrolyte undergoes severe thermal runaway at 147.9 ℃,demonstrating the key roles of the electrolyte on the thermal safety of batteries.On the contrary,thermal runaway does not occur for 45-cycle pouch cell despite the addition of the electrolyte.It is found that the higher-order polysulfides(Li_(2)S_(x) ≥ 6)are discovered in 16-cycle electrolyte while the sulfur species in 45-cycle electrolyte are Li_(2)S_(x) ≤ 4.In addition,strong exothermic reactions are discovered between cycled Li and dissolved higher-order polysulfide(Li_(2)S_(6) and Li_(2)S_(8))at 153.0 ℃,driving the thermal runaway of cycled Li-S pouch cells.This work uncovers the potential safety risks of Li-S batteries and negative roles of the polysulfide shuttle for Li-S batteries from the safety view.
基金supported by the National Natural Science Foundation of China(No.U20A20310 and No.52176199)sponsored by the Program of Shanghai Academic/Technology Research Leader(No.22XD1423800)。
文摘Thermal runaway(TR)is a critical issue hindering the large-scale application of lithium-ion batteries(LIBs).Understanding the thermal safety behavior of LIBs at the cell and module level under different state of charges(SOCs)has significant implications for reinforcing the thermal safety design of the lithium-ion battery module.This study first investigates the thermal safety boundary(TSB)correspondence at the cells and modules level under the guidance of a newly proposed concept,safe electric quantity boundary(SEQB).A reasonable thermal runaway propagation(TRP)judgment indicator,peak heat transfer power(PHTP),is proposed to predict whether TRP occurs.Moreover,a validated 3D model is used to quantitatively clarify the TSB at different SOCs from the perspective of PHTP,TR trigger temperature,SOC,and the full cycle life.Besides,three different TRP transfer modes are discovered.The interconversion relationship of three different TRP modes is investigated from the perspective of PHTP.This paper explores the TSB of LIBs under different SOCs at both cell and module levels for the first time,which has great significance in guiding the thermal safety design of battery systems.
基金supported by the National Natural Science Foundation of China(22179070,U1932220)the Natural Science Foundation of Jiangsu Province(BK20220073)the Fundamental Research Funds for the Central Universities(RF1028623157)。
文摘Safe batteries are the basis for next-generation application scenarios such as portable energy storage devices and electric vehicles,which are crucial to achieving carbon neutralization.Electrolytes,separators,and electrodes as main components of lithium batteries strongly affect the occurrence of safety accidents.Responsive materials,which can respond to external stimuli or environmental change,have triggered extensive attentions recently,holding great promise in facilitating safe and smart batteries.This review thoroughly discusses recent advances regarding the construction of high-safety lithium batteries based on internal thermal-responsive strategies,together with the corresponding changes in electrochemical performance under external stimulus.Furthermore,the existing challenges and outlook for the design of safe batteries are presented,creating valuable insights and proposing directions for the practical implementation of safe lithium batteries.
基金the project of the Open Research Fund Program of Science and Technology on Aerospace Chemical Power Laboratory(Grant No.STACPL320221B04)Key Laboratory of Explosion Science and Technology(Beijing Institute of Technology)The project number is ZDKT21-01.
文摘The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials.However,the impact of the above coupling on thermal hazard assessment is not considered in the literature studies.In this work,nitroguanidine(NQ)and 1,3,5-trinitro-1,3,5-triazine(RDX)are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical materials.The linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal analyser.The thermal decomposition curves are decoupled by advanced thermokinetics software.The thermal decomposition and kinetic parameters before and after decoupling are calculated.The results of TG experiment show that both NQ and RDX began to lose mass during the endothermic stage.The endothermic melting and exothermic decomposition of NQ and RDX are coupled within this stage.The coupling effect has different degrees of influence on its initial decomposition temperature and safety parameters.Compared with the parameters in the coupling state,the initial decomposition temperature and adiabatic induction period after decoupling decrease.The self-accelerating decomposition temperature increases,and internal thermal runaway time decreases.In the thermal hazard assessment of chemical materials with coupling effects,the calculated parameters after decoupling should be taken as an important safety index。
基金Project supported by the National Natural Science Foundation of China (Grant Nos.52211540005 and 52076087)the Natural Science Foundation of Hubei Province of China (Grant No.2023AFA072)+2 种基金the Open Project Program of Wuhan National Laboratory for Optoelectronics (Grant No.2021WNLOKF004)the Wuhan Knowledge Innovation Shuguang Programthe Science and Technology Program of Hubei Province of China (Grant No.2021BLB176)。
文摘Thermal illusion aims to create fake thermal signals or hide the thermal target from the background thermal field to mislead infrared observers,and illusion thermotics was proposed to regulate heat flux with artificially structured metamaterials for thermal illusion.Most theoretical and experimental works on illusion thermotics focus on two-dimensional materials,while heat transfer in real three-dimensional(3D)objects remains elusive,so the general 3D illusion thermotics is urgently demanded.In this study,we propose a general method to design 3D thermal illusion metamaterials with varying illusions at different sizes and positions.To validate the generality of the 3D method for thermal illusion metamaterials,we realize thermal functionalities of thermal shifting,splitting,trapping,amplifying and compressing.In addition,we propose a special way to simplify the design method under the condition that the size of illusion target is equal to the size of original heat source.The 3D thermal illusion metamaterial paves a general way for illusion thermotics and triggers the exploration of illusion metamaterials for more functionalities and applications.
基金the National Natural Science Foundation of China(Nos.52272046,52090030,52090031,52122301,51973191)the Natural Science Foundation of Zhejiang Province(LR23E020003)+4 种基金Shanxi-Zheda Institute of New Materials and Chemical Engineering(2021SZ-FR004,2022SZ-TD011,2022SZ-TD012,2022SZ-TD014)Hundred Talents Program of Zhejiang University(188020*194231701/113,112300+1944223R3/003,112300+1944223R3/004)the Fundamental Research Funds for the Central Universities(Nos.226-2023-00023,226-2023-00082,2021FZZX001-17,K20200060)National Key R&D Program of China(NO.2022YFA1205300,NO.2022YFA1205301,NO.2020YFF0204400,NO.2022YFF0609801)“Pioneer”and“Leading Goose”R&D Program of Zhejiang 2023C01190.
文摘Highly thermally conductive graphitic film(GF)materials have become a competitive solution for the thermal management of high-power electronic devices.However,their catastrophic structural failure under extreme alternating thermal/cold shock poses a significant challenge to reliability and safety.Here,we present the first investigation into the structural failure mechanism of GF during cyclic liquid nitrogen shocks(LNS),which reveals a bubbling process characterized by“permeation-diffusion-deformation”phenomenon.To overcome this long-standing structural weakness,a novel metal-nanoarmor strategy is proposed to construct a Cu-modified graphitic film(GF@Cu)with seamless heterointerface.This well-designed interface ensures superior structural stability for GF@Cu after hundreds of LNS cycles from 77 to 300 K.Moreover,GF@Cu maintains high thermal conductivity up to 1088 W m^(−1)K^(−1)with degradation of less than 5%even after 150 LNS cycles,superior to that of pure GF(50%degradation).Our work not only offers an opportunity to improve the robustness of graphitic films by the rational structural design but also facilitates the applications of thermally conductive carbon-based materials for future extreme thermal management in complex aerospace electronics.
文摘The temperature is one of the principal controlling parameters of oncological hyperthermia. However, local heating forms a complicated thermal distribution in space and has developed over time, too. The decisional factors are the heterogeneity of the targeted volume, the electrolyte perfusions controlled by thermal homeostasis, and the spreading of the heat energy with time. A further complication is that the energy absorption sharply changes by depth, so the spatiotemporal development of the temperature distribution requires specialized methods to control. Most of the temperature imaging facilities (thermography, radiometry, electric impedance tomography, etc.) are less precise than the medical practice needs. In contrast, precise point sensing (like thermocouples, thermistors, and fluoroptical methods) is invasive and measures only a discrete point in the robustly changing thermal map. The two most precise thermal imaging methods, computer tomography, and magnetic resonance are expensive and have numerous technical complications. Our objective is to show the complexity of the temperature distribution inside the human body, and offer a relatively simple and cheap method to visualize its spatiotemporal development. A novel emerging technology, the application of ultrasound microbubble contrast agents is a promising method for solving complicated tasks of thermal distribution deep inside the living body. Noteworthy, the temperature distribution does not determine the full hyperthermia process, nonthermal effects make considerable impact, too. Additionally to the difficulties to measure the thermal heterogeneity during hyperthermia in oncology, numerous nonthermal processes, molecular and structural changes are triggered by the incoming electromagnetic energy, which presently has no spatiotemporal visualization technique. Microbubble imaging has a suitable spatiotemporal thermal resolution, and also it is sensitive to nonthermal effects. Its application for characterization of the modulated electrohyperthermia (mEHT) may open a new theranostic facility, using the synergy of the thermal and nonthermal effects of the radiofrequency delivered energy. This complex approach gives facility to follow the mEHT processes, and the proposed microbubble ultrasound imaging has a particularly promising advantage sensing and acting also nonthermally, having potential to characterize the thermally conditioned nonthermal electromagnetic effects in oncologic hyperthermia. The mEHT combined with microbubble ultrasound images could be a robust theranostic method against cancer.
文摘In this paper,the mission and the thermal environment of the Solar Close Observations and Proximity Experiments(SCOPE)spacecraft are analyzed,and an advanced thermal management system(ATMS)is designed for it.The relationship and functions of the integrated database,the intelligent thermal control system and the efficient liquid cooling system in the ATMS are elaborated upon.For the complex thermal field regulation system and extreme space thermal environment,a modular simulation and thermal field planning method are proposed,and the feasibility of the planning algorithm is verified by numerical simulation.A solar array liquid cooling system is developed,and the system simulation results indicate that the temperatures of the solar arrays meet the requirements as the spacecraft flies by perihelion and aphelion.The advanced thermal management study supports the development of the SCOPE program and provides a reference for the thermal management in other deep-space exploration programs.
基金supported by the National Nature Science Foundation of China under grant No.42272350the Foundation of Shanxi Key Laboratory for Exploration and Exploitation of Geothermal Resources under grant No.SX202202.
文摘Underground Thermal Energy Storage(UTES)store unstable and non-continuous energy underground,releasing stable heat energy on demand.This effectively improve energy utilization and optimize energy allocation.As UTES technology advances,accommodating greater depth,higher temperature and multi-energy complementarity,new research challenges emerge.This paper comprehensively provides a systematic summary of the current research status of UTES.It categorized different types of UTES systems,analyzes the applicability of key technologies of UTES,and evaluate their economic and environmental benefits.Moreover,this paper identifies existing issues with UTES,such as injection blockage,wellbore scaling and corrosion,seepage and heat transfer in cracks,etc.It suggests deepening the research on blockage formation mechanism and plugging prevention technology,improving the study of anticorrosive materials and water treatment technology,and enhancing the investigation of reservoir fracture network characterization technology and seepage heat transfer.These recommendations serve as valuable references for promoting the high-quality development of UTES.
