Manufacturing thin-film components is crucial for achieving high-efficiency and high-power thermal batteries(TBs).However,developing binders with low-gas production at the operating temperature range of TBs(400-550...Manufacturing thin-film components is crucial for achieving high-efficiency and high-power thermal batteries(TBs).However,developing binders with low-gas production at the operating temperature range of TBs(400-550°C)has proven to be a significant challenge.Here,we report the use of acrylic acid derivative terpolymer(LA136D)as a low-volatile binder for thin-film cathode fabrication and studied the chain scission and chemical bondbreaking mechanisms in pyrolysis.It is shown LA136D defers to randomchain scission and cross-linking chain scission mechanisms,which gifts it with a low proportion of volatile products(ψ,ψ=39.2 wt%)at even up to 550°C,well below those of the conventional PVDF(77.6 wt%)and SBR(99.2 wt%)binders.Surprisingly,LA136D contributes to constructing a thermal shock-resistant cathode due to the step-by-step bond-breaking process.This is beneficial for the overall performance of TBs.In discharging test,the thin-film cathodes exhibited a remarkable 440%reduction in polarization and 300%enhancement in the utilization efficiency of cathode materials,while with just a slight increase of 0.05 MPa in gas pressure compared with traditional“thick-film”cathode.Our work highlights the potential of LA136D as a low-volatile binder for thin-film cathodes and shows the feasibility of manufacturing high-efficiency and high-power TBs through polymer molecule engineering.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
With the increasing requirements for fast charging and discharging,higher requirements have been put forward for the thermal management of power batteries.Therefore,there is an urgent need to develop efficient heat tr...With the increasing requirements for fast charging and discharging,higher requirements have been put forward for the thermal management of power batteries.Therefore,there is an urgent need to develop efficient heat transfer fluids.As a new type of heat transfer fluids,functional thermal fluids mainly includ-ing nanofluids(NFs)and phase change fluids(PCFs),have the advantages of high heat carrying density,high heat transfer rate,and broad operational temperature range.However,challenges that hinder their practical applications remain.In this paper,we firstly overview the classification,thermophysical prop-erties,drawbacks,and corresponding modifications of functional thermal fluids.For NFs,the high ther-mal conductivity and high convective heat transfer performance were mainly elaborated,while the stability and viscosity issues were also analyzed.And then for PCFs,the high heat carrying density was mainly elaborated,while the problems of supercooling,stability,and viscosity were also analyzed.On this basis,the composite fluids combined NFs and PCFs technology,has been summarized.Furthermore,the thermal properties of traditional fluids,NFs,PCFs,and composite fluids are compared,which proves that functional thermal fluids are a good choice to replace traditional fluids as coolants.Then,battery thermal management system(BTMS)based on functional thermal fluids is summarized in detail,and the thermal management effects and pump consumption are compared with that of water-based BTMS.Finally,the current technical challenges that parameters optimization of functional thermal fluids and structures optimization of BTMS systematically are presented.In the future,it is necessary to pay more attention to using machine learning to predict thermophysical properties of functional thermal fluids and their applications for BTMS under actual vehicle conditions.展开更多
With the increasing attention paid to battery technology,the microscopic reaction mechanism and macroscopic heat transfer process of lithium-ion batteries have been further studied and understood from both academic an...With the increasing attention paid to battery technology,the microscopic reaction mechanism and macroscopic heat transfer process of lithium-ion batteries have been further studied and understood from both academic and industrial perspectives.Temperature,as one of the key parameters in the physical fra mework of batteries,affects the performa nce of the multi-physical fields within the battery,a nd its effective control is crucial.Since the heat generation in the battery is determined by the real-time operating conditions,the battery temperature is essentially controlled by the real-time heat dissipation conditions provided by the battery thermal management system.Conventional battery thermal management systems have basic temperature control capabilities for most conventional application scenarios.However,with the current development of la rge-scale,integrated,and intelligent battery technology,the adva ncement of battery thermal management technology will pay more attention to the effective control of battery temperature under sophisticated situations,such as high power and widely varied operating conditions.In this context,this paper presents the latest advances and representative research related to battery thermal management system.Firstly,starting from battery thermal profile,the mechanism of battery heat generation is discussed in detail.Secondly,the static characteristics of the traditional battery thermal management system are summarized.Then,considering the dynamic requirements of battery heat dissipation under complex operating conditions,the concept of adaptive battery thermal management system is proposed based on specific research cases.Finally,the main challenges for battery thermal management system in practice are identified,and potential future developments to overcome these challenges are presented and discussed.展开更多
Nickel（II） chloride materials were synthesized via a novel two-step variable-temperature method for the use as a cathode material in Li-B/NiCI2 cells with the LiCI-LiBr- LiF electrolyte. The influence of temperature...Nickel（II） chloride materials were synthesized via a novel two-step variable-temperature method for the use as a cathode material in Li-B/NiCI2 cells with the LiCI-LiBr- LiF electrolyte. The influence of temperature on its structure, surface morphology, and electrochemical performance was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and electrochemical measurements of single cells. XRD results showed that after pre-dehydration for 2 h at 270℃ followed by sintering for 5 h at 600℃, the crystal water in nickel chloride hexahydrate could be removed effectively. The SEM results showed that particles recombined to form larger coarse particles and presented a layered structure. Discharge tests showed that the 600℃-treated materials demonstrated remarkable specific capacities of 210.42 and 242.84 mA h g^-1 at constant currents of 0.5 and 2.0 A, respectively. Therefore, the Li-B/NiCI2 thermal battery showed excellent discharge performance. The present work demonstrates that NiCl2 is a promising cathode material for thermal batteries and this two-step variable-temperature method is a simple and useful method for the fabrication of NiCl2 materials.展开更多
Thermal batteries（TBs） as primary power sources are widely applied in defense and military affairs, and used in electronic packages and nuclear weapons. The activation time（AT） of TBs restricts the reactive speed ...Thermal batteries（TBs） as primary power sources are widely applied in defense and military affairs, and used in electronic packages and nuclear weapons. The activation time（AT） of TBs restricts the reactive speed of them. Therefore, it is a remarkably important parameter and needs to be studied in detail. In our previous study, the thermal transfer model has already been found during the activation process in TBs. In this work, the experimental TBs were fabricated and tested for validating the model. The error between the average value of test and calculation value from this model is less than 1%. As a result, the thermal transfer function for the activation process in the given TBs[FeSJLiC1-KCI（MgO）/LiSi containing Fe/KC104 heat pellet] is suggested.展开更多
Phase change materials(PCMs)are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries(LIBs)according to real-time thermal conditions,guaranteeing the reliable operation of LIBs in b...Phase change materials(PCMs)are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries(LIBs)according to real-time thermal conditions,guaranteeing the reliable operation of LIBs in both cold and hot environments.Herein,we report a liquid metal(LM)modified polyethylene glycol/LM/boron nitride PCM,capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction.Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB’s structure and heat-conduction characteristic.Typically,soft and deformable LMs are modified on the boron nitride surface,serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m^(−1) K^(−1) in the vertical and in-plane directions,respectively.In addition,LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system.As a proof-of-concept,this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10℃ at high charging/discharging rate,opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway.展开更多
NiCl_(2) with high theoretical voltage and thermal decomposition temperature attracts much attention as cathode material for thermal batteries with the requirement of high power density, high energy density and long w...NiCl_(2) with high theoretical voltage and thermal decomposition temperature attracts much attention as cathode material for thermal batteries with the requirement of high power density, high energy density and long work time. Unfortunately, the practical utilization of thermal batteries with NiCl_(2) cathode is limited by their poor electrochemical performance under large current, even with the conventional Li F-Li Cl-Li Br all-lithium molten salt electrolyte which proposes ultrahigh lithium ion conductivity. In this work, an unexpected ionic exchange reaction between NiCl_(2) and Li Br in Li F-Li Cl-Li Br was found, which would be the main reason for the poor electrochemical behavior of thermal batteries with NiCl_(2) cathode and Li F-Li Cl-Li Br molten salt. On this basis, Li F-Li Cl-Li_(2)SO_(4), another all-lithium molten salt free of Li Br, was investigated as the new electrolyte for NiCl_(2) cathode. For the single cell of Li(Si)/Li F-Li Cl-Li_(2)SO_(4)/NiCl_(2), a discharge capacity of 377 mA h g^(-1)(with a cut-off voltage of 1.2 V) was achieved with large current density(500 mA cm^(-2)) applied at 520℃, which is almost twice of that of Li(Si)/Li F-Li Cl-Li Br/NiCl_(2)(190 mA h g^(-1)) at the same conditions.展开更多
The promotion of electric vehicles(EVs)is restricted due to their short cruising range.It is desirable to design an effective energy management strategy to improve their energy efficiency.Most existing work concerning...The promotion of electric vehicles(EVs)is restricted due to their short cruising range.It is desirable to design an effective energy management strategy to improve their energy efficiency.Most existing work concerning energy management strategies focused on hybrids rather than the EVs.The work focusing on the energy management strategy for EVs mainly uses the traditional optimization strategies,thereby limiting the advantages of energy economy.To this end,a novel energy management strategy that considered the impact of battery thermal effects was proposed with the help of reinforcement learning.The main idea was to first analyze the energy flow path of EVs,further formulize the energy management as an optimization problem,and finally propose an online strategy based on reinforcement learning to obtain the optimal strategy.Additionally,extensive simulation results have demonstrated that our strategy reduces energy consumption by at least 27.4%compared to the existing methods.展开更多
NASICON-type Na_(3)V_(2)(PO_(4))_(3) is a promising electrode material for developing advanced sodium-ion batteries.Preparing Na_(3)V_(2)(PO_(4))_(3) with good performance by a cost-effective and large-scale method is...NASICON-type Na_(3)V_(2)(PO_(4))_(3) is a promising electrode material for developing advanced sodium-ion batteries.Preparing Na_(3)V_(2)(PO_(4))_(3) with good performance by a cost-effective and large-scale method is significant for industrial applications.In this work,a porous Na_(3)V_(2)(PO_(4))_(3)/C cathode material with excellent electrochemical performance is successfully prepared by an agar-gel combined with freeze-drying method.The Na_(3)V_(2)(PO_(4))_(3)/C cathode displayed specific capacities of 113.4 mAh·g^(-1),107.0 mAh·g^(-1) and 87.1 mAh·g^(-1) at 0.1 C,1 C and 10 C,respectively.For the first time,the 500-mAh soft-packed symmetrical sodium-ion batteries based on Na_(3)V_(2)(PO_(4))_(3)/C electrodes are successfully fabricated.The 500-mAh symmetrical batteries exhibit outstanding low temperature performance with a capacity retention of 83%at 0℃ owing to the rapid sodium ion migration ability and structural stability of Na_(3)V_(2)(PO_(4))_(3)/C.Moreover,the thermal runaway features are revealed by accelerating rate calorimetry(ARC)test for the first time.Thermal stability and safety of the symmetrical batteries are demonstrated to be better than lithium-ion batteries and some reported sodium-ion batteries.Our work makes it clear that the soft-packed symmetrical sodium ion batteries based on Na_(3)V_(2)(PO_(4))_(3)/C have a prospect of practical application in high safety requirement fields.展开更多
Lithium-ion battery packs are made by many batteries, and the difficulty in heat transfer can cause many safety issues. It is important to evaluate thermal performance of a battery pack in designing process. Here, a m...Lithium-ion battery packs are made by many batteries, and the difficulty in heat transfer can cause many safety issues. It is important to evaluate thermal performance of a battery pack in designing process. Here, a multiscale method combining a pseudo-two-dimensional model of individual battery and three-dimensional computational fluid dynamics is employed to describe heat generation and transfer in a battery pack. The effect of battery arrangement on the thermal performance of battery packs is investigated. We discuss the air-cooling effect of the pack with four battery arrangements which include one square arrangement, one stagger arrangement and two trapezoid arrangements. In addition, the air-cooling strategy is studied by observing temperature distribution of the battery pack. It is found that the square arrangement is the structure with the best air-cooling effect, and the cooling effect is best when the cold air inlet is at the top of the battery pack. We hope that this work can provide theoretical guidance for thermal management of lithium-ion battery packs.展开更多
A comparative numerical study has been conducted on the thermal performance of a heat pipe cooling system considering several influential factors such as the coolant flow rate,the coolant inlet temperature,and the inp...A comparative numerical study has been conducted on the thermal performance of a heat pipe cooling system considering several influential factors such as the coolant flow rate,the coolant inlet temperature,and the input power.A comparison between numerical data and results available in the literature has demonstrated that our numerical procedure could successfully predict the heat transfer performance of the considered heat pipe cooling system for a battery.Specific indicators such as temperature,heat flux,and pressure loss were extracted to describe the characteristics of such a system.On the basis of the distributions of the temperature ratio of the battery surface,together with the heat flux and the streamlines around the heat pipe condenser,we conclude that the low disturbance of the coolant is the cause of the temperature gradient along the fluid flow direction.展开更多
In response to thermal runaway(TR)of electric vehicles,recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management.Thermal management with particular focus ...In response to thermal runaway(TR)of electric vehicles,recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management.Thermal management with particular focus on battery cooling has been becoming increasingly significant.TR usually happened when an electric vehicle is unpowered and charged.In this state,traditional active battery cooling schemes are disabled,which can easily lead to dangerous incidents due to loss of cooling ability,and advanced passive cooling strategies are therefore gaining importance.Herein,we developed an enhanced thermal radiation material,consisting of~1μm thick multilayered nano-sheet graphene film coated upon the heat dissipation surface,thereby enhancing thermal radiation in the nanoscale.The surface was characterized on the nanoscale,and tested in a battery-cooling scenario.We found that the graphene-based coating's spectral emissivity is between 91% and 95% in the mid-infrared region,and thermal experiments consequently illustrated that graphene-based radiative cooling yielded up to15.1% temperature reduction when compared to the uncoated analogue.Using the novel graphene surface to augment a heat pipe,the temperature reduction can be further enlarged to 25.6%.The new material may contribute to transportation safety,global warming mitigation and carbon neutralization.展开更多
This paper reports the performance investigation of a newly developed Latent Heat Thermal Battery(LHTB)integrated with a solar collector as the main source of heat.The LHTB is a new solution in the field of thermal st...This paper reports the performance investigation of a newly developed Latent Heat Thermal Battery(LHTB)integrated with a solar collector as the main source of heat.The LHTB is a new solution in the field of thermal storage and developed based on the battery concept in terms of recharge ability,portability and usability as a standalone device.It is fabricated based on the thermal battery storage concept and consists of a plate-fin and tube heat exchanger located inside the battery casing and paraffin wax which is used as a latent heat storage material.Solar thermal energy is absorbed by solar collector and transferred to the LHTB using water as Heat Transfer Fluid(HTF).Charging experiments have been conducted with a HTF at three different temperatures of 68°C,88°C and 108°C and three different flow rates of 30,60 and 120 l/h.It is followed by discharging experiments on fully charged LHTB at three different temperatures of 68°C,88°C and 108°C using HTF at three different flow rates of 30,60 and 120 l/h.It is found that both higher HTF inlet temperature and flow rate have a positive impact on stored thermal energy.However,charging efficiency was decreased by increasing the HTF flow rate.The highest charging efficiency of 29%was achieved using HTF of 108°C at a flow rate of 30 l/h.Most of paraffin melted in this case,while part of the paraffin remained solid in other experiments.On the other hand,the results from discharging experiments revealed that both recovered thermal energy and recovery efficiency increased by either increasing the LHTB temperature or HTF flow rate.Highest recovered thermal energy of 5,825 KJ at 35%recovery efficiency achieved at LHTB of 108°C using 120 l/h of HTF.展开更多
Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of...Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide(GO) modified anion exchange membrane(AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result,it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.展开更多
This research evaluates the performance of a Phase Change Material(PCM)battery integrated into the climate system of a new transparent meeting center.The main research questions are:a.“Can the performance of the batt...This research evaluates the performance of a Phase Change Material(PCM)battery integrated into the climate system of a new transparent meeting center.The main research questions are:a.“Can the performance of the battery be calculated?”and b.“Can the battery reduce the heating and cooling energy demand in a significant way?”The first question is answered in this document.In order to be able to answer the second question,especially the way the heat loading in winter should be improved,then more research is necessary.In addition to the thermal battery,which consists of Phase Change Material plates,the climate system has a cross-flow heat exchanger and a heat pump.The battery should play a central role in closing the thermal balance of the lightweight building,which can be loaded with hot return or cold outdoor air.The temperature of the battery plates is monitored by multi-sensors and simulated by the use of PHOENICS(Computational Fluid Dynamics)and MATLAB.This paper reports reasonable agreement between the numerical predictions and the measurements,with a maximum variance of 10%.The current coefficient of performance for heating and cooling is already high,more than 27.There is scope for increasing this much further by making use of the very low-pressure difference of the battery(below 25 Pascal),low pressure fans and the ventilation system as a whole.展开更多
Lithium-ion batteries are expected to operate within a narrow temperature window around room temperature for optimal performance and lifetime.Therefore,in cold environments,electric vehicle battery packs must be exten...Lithium-ion batteries are expected to operate within a narrow temperature window around room temperature for optimal performance and lifetime.Therefore,in cold environments,electric vehicle battery packs must be extensively preheated prior to charge or discharge.However,conventional preheating is accomplished externally,which is slow and thus significantly increases charging times.Recently,internal heating has been demonstrated as a potential solution to quickly and uniformly preheat a lithium-ion pouch cell.However,internal heating has not been evaluated in other battery formats such as cylindrical batteries.In this work,we present a numerical model of a 4680 battery with internal heaters for fast preheating in cold environments.The effects that the number of heater layers,heating duration,resting duration,environmental temperature,and boundary heat transfer coefficient have on the temperature heterogeneity of the battery were investigated.The results show that internal heating alone reduces the temperature variation within the battery by a factor of 5 compared to external heating,and by a factor of 20 when combining internal and external heating.This study further proves that internal preheating of lithium-ion batteries is a promising thermal management strategy,and provides guidance on potential design considerations and heating protocols to implement internal heating.展开更多
In this paper,a model predictive control(MPC)based on back propagation neural network(BPNN)prediction model was proposed for compressor speed control of air conditioning system(ACS)and battery thermal management syste...In this paper,a model predictive control(MPC)based on back propagation neural network(BPNN)prediction model was proposed for compressor speed control of air conditioning system(ACS)and battery thermal management system(BTMS)coupling system of battery electric vehicle(BEV).In order to solve the problem of high cooling energy consumption and inferior thermal comfort in the cabin of the battery electric vehicle thermal management system(BEVTMS)during summer time,this paper combines the respective superiorities of artificial neural network(ANN)predictive modeling and MPC,and creatively combines the two methods and uses them in the control of BEVTMS.Firstly,based on ANN and heat transfer theory,BPNN prediction model,ACS and BTMS coupling system were established and verified.Secondly,a mathematical method of MPC was established to control the speed of the compressor.Then,the state parameters of the coupled system were predicted using a BPNN prediction model,and the predicted values were passed to the MPC,thus achieving accurate control of the compressor speed using the MPC.Finally,the effects of PID control and MPC based on BPNN prediction model on thermal comfort of cabin and compressor energy consumption at different ambient temperatures were compared in simulation under New European Driving Cycle(NEDC)conditions.The results showed for the constructed BPNN prediction model predicted and tested values of the selected parameters the mean squared error(MSE)ranged from 2.498%to 8.969%,mean absolute percentage error(MAPE)ranged from 4.197%to 8.986%,and mean absolute error(MAE)ranged from 3.202%to 8.476%.At ambient temperatures of 25℃,35℃ and 45℃,the MPC based on the BPNN prediction model reduced the cumulative discomfort time in the cabin by 100 s,39 s and 19 s,respectively,compared with the PID control.Under three NEDC conditions,the energy consumption is reduced by 1.82%,2.35%and 3.48%,respectively.When the ambient temperature was 35℃,the MPC based on BPNN prediction model can make the ACS and BTMS coupling system have better thermal comfort,and the energy saving effect of the compressor was more obvious with the temperature.展开更多
Electric vehicles(EVs)are globally undergoing rapid developments,and have great potentials to replace the traditional vehicles based on fossil fuels.Power-type lithium-ion batteries(LIBs)have been widely used for EVs,...Electric vehicles(EVs)are globally undergoing rapid developments,and have great potentials to replace the traditional vehicles based on fossil fuels.Power-type lithium-ion batteries(LIBs)have been widely used for EVs,owing to high power densities,good charge/discharge stability,and long cycle life.The driving ranges and acceleration performances are gaining increasing concerns from customers,which depend highly on the power level of LIBs.With the increase in power outputs,rising heat generation significantly affects the battery performances,and in particular operation safety.Meanwhile,the cold-start performance is still an intractable problem under extreme conditions.These challenges put forward higher requirements for a dedicated battery thermal management system(BTMS).Compared to traditional BTMSs in EVs,the heat pipe-based BTMS has great application prospects owing to its compact structure,flexibility,low cost,and especially high thermal conductivity.Encompassing this topic,this review first introduces heat generation phenomena and temperature characteristics of LIBs.Multiple abuse conditions and thermal runaway issues are described afterward.Typical cooling and preheating methods for designing a BTMS are also discussed.More emphasis on this review is put on the use of various heat pipes for BTMSs to enhance the thermal performances of LIBs.For lack of wide application in actual EVs,more efforts should be made to extend the use of heat pipes for constructing an energy-efficient,cost-effective,and reliable BTMS to improve the performances and safety of EVs.展开更多
The age softening phenomenon of the Li−B alloy was investigated by a series of tensile tests under various aging conditions.The results show that the tensile strength of the rolled Li−B alloy decreases with increasing...The age softening phenomenon of the Li−B alloy was investigated by a series of tensile tests under various aging conditions.The results show that the tensile strength of the rolled Li−B alloy decreases with increasing aging time.Higher aging temperature accelerates the softening process,and leads to an early end of aging.A model was proposed to analyze the mechanism of the age softening.The vacancy annihilation is the control factor of age softening.The strength−temperature relationship was estimated by the newly proposed model and a standard heat treatment,annealing at 150℃ for 1 h,was designed to eliminate the age softening of rolled Li−B alloy.展开更多
基金the support from the China Academy of Engineering Physicsthe National Natural Science Foundation of China(NSFC-No.52102319,12104422,U1930208)
文摘Manufacturing thin-film components is crucial for achieving high-efficiency and high-power thermal batteries(TBs).However,developing binders with low-gas production at the operating temperature range of TBs(400-550°C)has proven to be a significant challenge.Here,we report the use of acrylic acid derivative terpolymer(LA136D)as a low-volatile binder for thin-film cathode fabrication and studied the chain scission and chemical bondbreaking mechanisms in pyrolysis.It is shown LA136D defers to randomchain scission and cross-linking chain scission mechanisms,which gifts it with a low proportion of volatile products(ψ,ψ=39.2 wt%)at even up to 550°C,well below those of the conventional PVDF(77.6 wt%)and SBR(99.2 wt%)binders.Surprisingly,LA136D contributes to constructing a thermal shock-resistant cathode due to the step-by-step bond-breaking process.This is beneficial for the overall performance of TBs.In discharging test,the thin-film cathodes exhibited a remarkable 440%reduction in polarization and 300%enhancement in the utilization efficiency of cathode materials,while with just a slight increase of 0.05 MPa in gas pressure compared with traditional“thick-film”cathode.Our work highlights the potential of LA136D as a low-volatile binder for thin-film cathodes and shows the feasibility of manufacturing high-efficiency and high-power TBs through polymer molecule engineering.
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supported by the National Natural Science Foundation of China(Grant No.52271320)"Mechanics+"interdisciplinary innovation youth fund project of Ningbo University(LJ2023005).
文摘With the increasing requirements for fast charging and discharging,higher requirements have been put forward for the thermal management of power batteries.Therefore,there is an urgent need to develop efficient heat transfer fluids.As a new type of heat transfer fluids,functional thermal fluids mainly includ-ing nanofluids(NFs)and phase change fluids(PCFs),have the advantages of high heat carrying density,high heat transfer rate,and broad operational temperature range.However,challenges that hinder their practical applications remain.In this paper,we firstly overview the classification,thermophysical prop-erties,drawbacks,and corresponding modifications of functional thermal fluids.For NFs,the high ther-mal conductivity and high convective heat transfer performance were mainly elaborated,while the stability and viscosity issues were also analyzed.And then for PCFs,the high heat carrying density was mainly elaborated,while the problems of supercooling,stability,and viscosity were also analyzed.On this basis,the composite fluids combined NFs and PCFs technology,has been summarized.Furthermore,the thermal properties of traditional fluids,NFs,PCFs,and composite fluids are compared,which proves that functional thermal fluids are a good choice to replace traditional fluids as coolants.Then,battery thermal management system(BTMS)based on functional thermal fluids is summarized in detail,and the thermal management effects and pump consumption are compared with that of water-based BTMS.Finally,the current technical challenges that parameters optimization of functional thermal fluids and structures optimization of BTMS systematically are presented.In the future,it is necessary to pay more attention to using machine learning to predict thermophysical properties of functional thermal fluids and their applications for BTMS under actual vehicle conditions.
基金supported by the National Natural Science Foundation of China (No.62373224,62333013,and U23A20327)。
文摘With the increasing attention paid to battery technology,the microscopic reaction mechanism and macroscopic heat transfer process of lithium-ion batteries have been further studied and understood from both academic and industrial perspectives.Temperature,as one of the key parameters in the physical fra mework of batteries,affects the performa nce of the multi-physical fields within the battery,a nd its effective control is crucial.Since the heat generation in the battery is determined by the real-time operating conditions,the battery temperature is essentially controlled by the real-time heat dissipation conditions provided by the battery thermal management system.Conventional battery thermal management systems have basic temperature control capabilities for most conventional application scenarios.However,with the current development of la rge-scale,integrated,and intelligent battery technology,the adva ncement of battery thermal management technology will pay more attention to the effective control of battery temperature under sophisticated situations,such as high power and widely varied operating conditions.In this context,this paper presents the latest advances and representative research related to battery thermal management system.Firstly,starting from battery thermal profile,the mechanism of battery heat generation is discussed in detail.Secondly,the static characteristics of the traditional battery thermal management system are summarized.Then,considering the dynamic requirements of battery heat dissipation under complex operating conditions,the concept of adaptive battery thermal management system is proposed based on specific research cases.Finally,the main challenges for battery thermal management system in practice are identified,and potential future developments to overcome these challenges are presented and discussed.
基金supported by Shanghai Institute of Space Power-sources(SISP)
文摘Nickel（II） chloride materials were synthesized via a novel two-step variable-temperature method for the use as a cathode material in Li-B/NiCI2 cells with the LiCI-LiBr- LiF electrolyte. The influence of temperature on its structure, surface morphology, and electrochemical performance was investigated by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, and electrochemical measurements of single cells. XRD results showed that after pre-dehydration for 2 h at 270℃ followed by sintering for 5 h at 600℃, the crystal water in nickel chloride hexahydrate could be removed effectively. The SEM results showed that particles recombined to form larger coarse particles and presented a layered structure. Discharge tests showed that the 600℃-treated materials demonstrated remarkable specific capacities of 210.42 and 242.84 mA h g^-1 at constant currents of 0.5 and 2.0 A, respectively. Therefore, the Li-B/NiCI2 thermal battery showed excellent discharge performance. The present work demonstrates that NiCl2 is a promising cathode material for thermal batteries and this two-step variable-temperature method is a simple and useful method for the fabrication of NiCl2 materials.
基金Supported by the National Natural Science Foundation of China（No.21573093）.
文摘Thermal batteries（TBs） as primary power sources are widely applied in defense and military affairs, and used in electronic packages and nuclear weapons. The activation time（AT） of TBs restricts the reactive speed of them. Therefore, it is a remarkably important parameter and needs to be studied in detail. In our previous study, the thermal transfer model has already been found during the activation process in TBs. In this work, the experimental TBs were fabricated and tested for validating the model. The error between the average value of test and calculation value from this model is less than 1%. As a result, the thermal transfer function for the activation process in the given TBs[FeSJLiC1-KCI（MgO）/LiSi containing Fe/KC104 heat pellet] is suggested.
基金This work was financially supported by the National Natural Science Foundation of China(No.52103091)the Natural Science Foundation of Jiangsu Province(No.BK20200501)the State Key Laboratory of Polymer Materials Engineering(No.sklpme2022-3-15).
文摘Phase change materials(PCMs)are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries(LIBs)according to real-time thermal conditions,guaranteeing the reliable operation of LIBs in both cold and hot environments.Herein,we report a liquid metal(LM)modified polyethylene glycol/LM/boron nitride PCM,capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction.Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB’s structure and heat-conduction characteristic.Typically,soft and deformable LMs are modified on the boron nitride surface,serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m^(−1) K^(−1) in the vertical and in-plane directions,respectively.In addition,LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system.As a proof-of-concept,this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10℃ at high charging/discharging rate,opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway.
基金supported by the National Nature Science Associate Foundation (NSAF) of China (Grant No. U1930208)the Laboratory of Precision Manufacturing Technology+2 种基金China Academy of Engineering Physics (Grant No. ZD17006,ZM18002)the National Natural Science Foundation of China (Grant Nos. 11804312 and 21703215)the Science and Technology Innovation Foundation of Institute of Electronic Engineering (Grant No. S201904)。
文摘NiCl_(2) with high theoretical voltage and thermal decomposition temperature attracts much attention as cathode material for thermal batteries with the requirement of high power density, high energy density and long work time. Unfortunately, the practical utilization of thermal batteries with NiCl_(2) cathode is limited by their poor electrochemical performance under large current, even with the conventional Li F-Li Cl-Li Br all-lithium molten salt electrolyte which proposes ultrahigh lithium ion conductivity. In this work, an unexpected ionic exchange reaction between NiCl_(2) and Li Br in Li F-Li Cl-Li Br was found, which would be the main reason for the poor electrochemical behavior of thermal batteries with NiCl_(2) cathode and Li F-Li Cl-Li Br molten salt. On this basis, Li F-Li Cl-Li_(2)SO_(4), another all-lithium molten salt free of Li Br, was investigated as the new electrolyte for NiCl_(2) cathode. For the single cell of Li(Si)/Li F-Li Cl-Li_(2)SO_(4)/NiCl_(2), a discharge capacity of 377 mA h g^(-1)(with a cut-off voltage of 1.2 V) was achieved with large current density(500 mA cm^(-2)) applied at 520℃, which is almost twice of that of Li(Si)/Li F-Li Cl-Li Br/NiCl_(2)(190 mA h g^(-1)) at the same conditions.
基金National Natural Science Foundation of China(Nos.61772130 and 62072096)Fundamental Research Funds for the Central Universities+2 种基金China(No.2232020A-12)International Cooperation Program of Shanghai Science and Technology Commission,China(No.20220713000)Young Top-Notch Talent Program in Shanghai,China。
文摘The promotion of electric vehicles(EVs)is restricted due to their short cruising range.It is desirable to design an effective energy management strategy to improve their energy efficiency.Most existing work concerning energy management strategies focused on hybrids rather than the EVs.The work focusing on the energy management strategy for EVs mainly uses the traditional optimization strategies,thereby limiting the advantages of energy economy.To this end,a novel energy management strategy that considered the impact of battery thermal effects was proposed with the help of reinforcement learning.The main idea was to first analyze the energy flow path of EVs,further formulize the energy management as an optimization problem,and finally propose an online strategy based on reinforcement learning to obtain the optimal strategy.Additionally,extensive simulation results have demonstrated that our strategy reduces energy consumption by at least 27.4%compared to the existing methods.
基金This work was supported by the National Key Research and Development Program(2016YFB0901505)the Natural Science Foundation of China(22005190,21938005)+1 种基金the Science&Technology Commission of Shanghai Municipality(19DZ1205500)Zhejiang Key Research and Development Program(2020C01128).
文摘NASICON-type Na_(3)V_(2)(PO_(4))_(3) is a promising electrode material for developing advanced sodium-ion batteries.Preparing Na_(3)V_(2)(PO_(4))_(3) with good performance by a cost-effective and large-scale method is significant for industrial applications.In this work,a porous Na_(3)V_(2)(PO_(4))_(3)/C cathode material with excellent electrochemical performance is successfully prepared by an agar-gel combined with freeze-drying method.The Na_(3)V_(2)(PO_(4))_(3)/C cathode displayed specific capacities of 113.4 mAh·g^(-1),107.0 mAh·g^(-1) and 87.1 mAh·g^(-1) at 0.1 C,1 C and 10 C,respectively.For the first time,the 500-mAh soft-packed symmetrical sodium-ion batteries based on Na_(3)V_(2)(PO_(4))_(3)/C electrodes are successfully fabricated.The 500-mAh symmetrical batteries exhibit outstanding low temperature performance with a capacity retention of 83%at 0℃ owing to the rapid sodium ion migration ability and structural stability of Na_(3)V_(2)(PO_(4))_(3)/C.Moreover,the thermal runaway features are revealed by accelerating rate calorimetry(ARC)test for the first time.Thermal stability and safety of the symmetrical batteries are demonstrated to be better than lithium-ion batteries and some reported sodium-ion batteries.Our work makes it clear that the soft-packed symmetrical sodium ion batteries based on Na_(3)V_(2)(PO_(4))_(3)/C have a prospect of practical application in high safety requirement fields.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 91834301 and 22078088)the National Natural Science Foundation of China for Innovative Research Groups (Grant No. 51621002)the Shanghai Rising-Star Program (Grant No. 21QA1401900)。
文摘Lithium-ion battery packs are made by many batteries, and the difficulty in heat transfer can cause many safety issues. It is important to evaluate thermal performance of a battery pack in designing process. Here, a multiscale method combining a pseudo-two-dimensional model of individual battery and three-dimensional computational fluid dynamics is employed to describe heat generation and transfer in a battery pack. The effect of battery arrangement on the thermal performance of battery packs is investigated. We discuss the air-cooling effect of the pack with four battery arrangements which include one square arrangement, one stagger arrangement and two trapezoid arrangements. In addition, the air-cooling strategy is studied by observing temperature distribution of the battery pack. It is found that the square arrangement is the structure with the best air-cooling effect, and the cooling effect is best when the cold air inlet is at the top of the battery pack. We hope that this work can provide theoretical guidance for thermal management of lithium-ion battery packs.
基金by the Natural Science Foundation of Jiangsu Province(Grants No.BK20170317).
文摘A comparative numerical study has been conducted on the thermal performance of a heat pipe cooling system considering several influential factors such as the coolant flow rate,the coolant inlet temperature,and the input power.A comparison between numerical data and results available in the literature has demonstrated that our numerical procedure could successfully predict the heat transfer performance of the considered heat pipe cooling system for a battery.Specific indicators such as temperature,heat flux,and pressure loss were extracted to describe the characteristics of such a system.On the basis of the distributions of the temperature ratio of the battery surface,together with the heat flux and the streamlines around the heat pipe condenser,we conclude that the low disturbance of the coolant is the cause of the temperature gradient along the fluid flow direction.
基金supported by the National Natural Science Foundation of China(no.52106114)Beijing Natural Science Foundation(no.3234061)Hong Kong Scholars Program(no.XJ2022027)。
文摘In response to thermal runaway(TR)of electric vehicles,recent attention has been focused on mitigation strategies such as efficient heat dredging in battery thermal management.Thermal management with particular focus on battery cooling has been becoming increasingly significant.TR usually happened when an electric vehicle is unpowered and charged.In this state,traditional active battery cooling schemes are disabled,which can easily lead to dangerous incidents due to loss of cooling ability,and advanced passive cooling strategies are therefore gaining importance.Herein,we developed an enhanced thermal radiation material,consisting of~1μm thick multilayered nano-sheet graphene film coated upon the heat dissipation surface,thereby enhancing thermal radiation in the nanoscale.The surface was characterized on the nanoscale,and tested in a battery-cooling scenario.We found that the graphene-based coating's spectral emissivity is between 91% and 95% in the mid-infrared region,and thermal experiments consequently illustrated that graphene-based radiative cooling yielded up to15.1% temperature reduction when compared to the uncoated analogue.Using the novel graphene surface to augment a heat pipe,the temperature reduction can be further enlarged to 25.6%.The new material may contribute to transportation safety,global warming mitigation and carbon neutralization.
基金the University of Malaya,Faculty of Engineering,Faculty Research Grant No.GPF023A-2019.
文摘This paper reports the performance investigation of a newly developed Latent Heat Thermal Battery(LHTB)integrated with a solar collector as the main source of heat.The LHTB is a new solution in the field of thermal storage and developed based on the battery concept in terms of recharge ability,portability and usability as a standalone device.It is fabricated based on the thermal battery storage concept and consists of a plate-fin and tube heat exchanger located inside the battery casing and paraffin wax which is used as a latent heat storage material.Solar thermal energy is absorbed by solar collector and transferred to the LHTB using water as Heat Transfer Fluid(HTF).Charging experiments have been conducted with a HTF at three different temperatures of 68°C,88°C and 108°C and three different flow rates of 30,60 and 120 l/h.It is followed by discharging experiments on fully charged LHTB at three different temperatures of 68°C,88°C and 108°C using HTF at three different flow rates of 30,60 and 120 l/h.It is found that both higher HTF inlet temperature and flow rate have a positive impact on stored thermal energy.However,charging efficiency was decreased by increasing the HTF flow rate.The highest charging efficiency of 29%was achieved using HTF of 108°C at a flow rate of 30 l/h.Most of paraffin melted in this case,while part of the paraffin remained solid in other experiments.On the other hand,the results from discharging experiments revealed that both recovered thermal energy and recovery efficiency increased by either increasing the LHTB temperature or HTF flow rate.Highest recovered thermal energy of 5,825 KJ at 35%recovery efficiency achieved at LHTB of 108°C using 120 l/h of HTF.
基金supported by Innovative Research Group Project of National Natural Science Foundation of China (No. 52021004)National Natural Science Foundation of China (No. 51976018)+1 种基金Scientific Research Foundation for Returned Overseas Chinese Scholars of Chongqing, China (No. cx2021088)Research Funds of Key Laboratory of Low-grade Energy Utilization Technologies and Systems (No. LLEUTS-2018005)。
文摘Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide(GO) modified anion exchange membrane(AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result,it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.
基金The project is financed via a public grant of the Rijksdienst Voor Ondernemend Nederland(RVO,https://www.rvo.nl/)within the Urban Energy 2018 Research-Line with Grant No.TEUE318008.The grant is awarded to the following consortium:The Delft University of Technology(https://www.tudelft.nl/en),Van Dorp B.V.,Hunter Douglas Europe B.V.(https://www.hunterdouglasarchitectural.eu/),Priva B.V.(https://www.priva.com/nl)and the Green Village Foundation(https://www.thegreenvillage.org/en/).
文摘This research evaluates the performance of a Phase Change Material(PCM)battery integrated into the climate system of a new transparent meeting center.The main research questions are:a.“Can the performance of the battery be calculated?”and b.“Can the battery reduce the heating and cooling energy demand in a significant way?”The first question is answered in this document.In order to be able to answer the second question,especially the way the heat loading in winter should be improved,then more research is necessary.In addition to the thermal battery,which consists of Phase Change Material plates,the climate system has a cross-flow heat exchanger and a heat pump.The battery should play a central role in closing the thermal balance of the lightweight building,which can be loaded with hot return or cold outdoor air.The temperature of the battery plates is monitored by multi-sensors and simulated by the use of PHOENICS(Computational Fluid Dynamics)and MATLAB.This paper reports reasonable agreement between the numerical predictions and the measurements,with a maximum variance of 10%.The current coefficient of performance for heating and cooling is already high,more than 27.There is scope for increasing this much further by making use of the very low-pressure difference of the battery(below 25 Pascal),low pressure fans and the ventilation system as a whole.
基金supported by an Early Career Faculty grant from NASA’s Space Technology Research Grants Program(No.80NSSC23K0072)the National Science Foundation Graduate Research Fellowships Program(No.2139319).
文摘Lithium-ion batteries are expected to operate within a narrow temperature window around room temperature for optimal performance and lifetime.Therefore,in cold environments,electric vehicle battery packs must be extensively preheated prior to charge or discharge.However,conventional preheating is accomplished externally,which is slow and thus significantly increases charging times.Recently,internal heating has been demonstrated as a potential solution to quickly and uniformly preheat a lithium-ion pouch cell.However,internal heating has not been evaluated in other battery formats such as cylindrical batteries.In this work,we present a numerical model of a 4680 battery with internal heaters for fast preheating in cold environments.The effects that the number of heater layers,heating duration,resting duration,environmental temperature,and boundary heat transfer coefficient have on the temperature heterogeneity of the battery were investigated.The results show that internal heating alone reduces the temperature variation within the battery by a factor of 5 compared to external heating,and by a factor of 20 when combining internal and external heating.This study further proves that internal preheating of lithium-ion batteries is a promising thermal management strategy,and provides guidance on potential design considerations and heating protocols to implement internal heating.
基金supported by the Natural Science Foundation of Chongqing (Grant No:cstc2021jcyj-msxmX0440)the youth project of science and technology research program of Chongqing Education Commission of China (Grant No:KJQN202301167)+3 种基金the Chongqing Graduate Education Teaching Reform Research Project (Grant No:YJG233120)the Special Major Project of Technological Innovation and Application Development of Chongqing(Grant No:CSTB2022TIAD-STX0002)Chongqing university of technology graduate education quality development action plan funding results-graduate student innovation program (Grant No:gzlcx20232026)the graduate student innovation projects (Grant No:gzlcx20232029)
文摘In this paper,a model predictive control(MPC)based on back propagation neural network(BPNN)prediction model was proposed for compressor speed control of air conditioning system(ACS)and battery thermal management system(BTMS)coupling system of battery electric vehicle(BEV).In order to solve the problem of high cooling energy consumption and inferior thermal comfort in the cabin of the battery electric vehicle thermal management system(BEVTMS)during summer time,this paper combines the respective superiorities of artificial neural network(ANN)predictive modeling and MPC,and creatively combines the two methods and uses them in the control of BEVTMS.Firstly,based on ANN and heat transfer theory,BPNN prediction model,ACS and BTMS coupling system were established and verified.Secondly,a mathematical method of MPC was established to control the speed of the compressor.Then,the state parameters of the coupled system were predicted using a BPNN prediction model,and the predicted values were passed to the MPC,thus achieving accurate control of the compressor speed using the MPC.Finally,the effects of PID control and MPC based on BPNN prediction model on thermal comfort of cabin and compressor energy consumption at different ambient temperatures were compared in simulation under New European Driving Cycle(NEDC)conditions.The results showed for the constructed BPNN prediction model predicted and tested values of the selected parameters the mean squared error(MSE)ranged from 2.498%to 8.969%,mean absolute percentage error(MAPE)ranged from 4.197%to 8.986%,and mean absolute error(MAE)ranged from 3.202%to 8.476%.At ambient temperatures of 25℃,35℃ and 45℃,the MPC based on the BPNN prediction model reduced the cumulative discomfort time in the cabin by 100 s,39 s and 19 s,respectively,compared with the PID control.Under three NEDC conditions,the energy consumption is reduced by 1.82%,2.35%and 3.48%,respectively.When the ambient temperature was 35℃,the MPC based on BPNN prediction model can make the ACS and BTMS coupling system have better thermal comfort,and the energy saving effect of the compressor was more obvious with the temperature.
基金supported by the Key-Area Research and Development Program of Guangdong Province(Grant Nos.2019B090909001 and 2020B090920002)the National Natural Science Foundation of China(Grant Nos.51975218 and 51722504)+1 种基金Guangdong Science and Technology Plan Program(Grant No.2017KZ010105)Fundamental Research Funds for the Central Universities(Grant No.2018ZD31)。
文摘Electric vehicles(EVs)are globally undergoing rapid developments,and have great potentials to replace the traditional vehicles based on fossil fuels.Power-type lithium-ion batteries(LIBs)have been widely used for EVs,owing to high power densities,good charge/discharge stability,and long cycle life.The driving ranges and acceleration performances are gaining increasing concerns from customers,which depend highly on the power level of LIBs.With the increase in power outputs,rising heat generation significantly affects the battery performances,and in particular operation safety.Meanwhile,the cold-start performance is still an intractable problem under extreme conditions.These challenges put forward higher requirements for a dedicated battery thermal management system(BTMS).Compared to traditional BTMSs in EVs,the heat pipe-based BTMS has great application prospects owing to its compact structure,flexibility,low cost,and especially high thermal conductivity.Encompassing this topic,this review first introduces heat generation phenomena and temperature characteristics of LIBs.Multiple abuse conditions and thermal runaway issues are described afterward.Typical cooling and preheating methods for designing a BTMS are also discussed.More emphasis on this review is put on the use of various heat pipes for BTMSs to enhance the thermal performances of LIBs.For lack of wide application in actual EVs,more efforts should be made to extend the use of heat pipes for constructing an energy-efficient,cost-effective,and reliable BTMS to improve the performances and safety of EVs.
基金Project(50172062)supported by the National Natural Science Foundation of China。
文摘The age softening phenomenon of the Li−B alloy was investigated by a series of tensile tests under various aging conditions.The results show that the tensile strength of the rolled Li−B alloy decreases with increasing aging time.Higher aging temperature accelerates the softening process,and leads to an early end of aging.A model was proposed to analyze the mechanism of the age softening.The vacancy annihilation is the control factor of age softening.The strength−temperature relationship was estimated by the newly proposed model and a standard heat treatment,annealing at 150℃ for 1 h,was designed to eliminate the age softening of rolled Li−B alloy.
