Effect of safety valve types on the gas venting behavior and thermal runaway hazard severity of large-format prismatic lithium iron phosphate batteries

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.

Early warning method for thermal runaway of lithium-ion batteries under thermal abuse condition based on online electrochemical impedance monitoring

Early warning of thermal runaway(TR)of lithium-ion batteries(LIBs)is a significant challenge in current application scenarios.Timely and effective TR early warning technology is urgently required considering the current fire safety situation of LIBs.In this work,we report an early warning method of TR with online electrochemical impedance spectroscopy(EIS)monitoring,which overcomes the shortcomings of warning methods based on traditional signals such as temperature,gas,and pressure with obvious delay and high cost.With in-situ data acquisition through accelerating rate calorimeter(ARC)-EIS test,the crucial features of TR were extracted using the RReliefF algorithm.TR mechanisms corresponding to the features at specific frequencies were analyzed.Finally,a three-level warning strategy for single battery,series module,and parallel module was formulated,which can successfully send out an early warning signal ahead of the self-heating temperature of battery under thermal abuse condition.The technology can provide a reliable basis for the timely intervention of battery thermal management and fire protection systems and is expected to be applied to electric vehicles and energy storage devices to realize early warning and improve battery safety.

Thermal runaway evolution of a 280 Ah lithium-ion battery with LiFePO_(4) as the cathode for different heat transfer modes constructed by mechanical abuse

Lithium iron phosphate batteries have been increasingly utilized in recent years because their higher safety performance can improve the increasing trend of recurring thermal runaway accidents.However,the safety performance and mechanism of high-capacity lithium iron phosphate batteries under internal short-circuit challenges remain to be explored.This work analyzes the thermal runaway evolution of high-capacity LiFePO_(4) batteries under different internal heat transfer modes,which are controlled by different penetration modes.Two penetration cases involving complete penetration and incomplete penetration were detected during the test,and two modes were performed incorporating nails that either remained or were removed after penetration to comprehensively reveal the thermal runaway mechanism.A theoretical model of microcircuits and internal heat conduction is also established.The results indicated three thermal runaway evolution processes for high-capacity batteries,which corresponded to the experimental results of thermal equilibrium,single thermal runaway,and two thermal runaway events.The difference in heat distribution in the three phenomena is determined based on the microstructure and material structure near the pinhole.By controlling the heat dissipation conditions,the time interval between two thermal runaway events can be delayed from 558 to 1417 s,accompanied by a decrease in the concentration of in-situ gas production during the second thermal runaway event.

Assessing environmental impact:Micro-energy network optimization in a Chinese industrial park

Micro-energy systems contribute significantly to environmental improvement by reducing dependence on power grids through the utilization of multiple renewable energy sources.This study quantified the environmental impact of a micro-energy network system in an industrial park through a life cycle assessment using the operation of the micro-energy network over a year as the functional unit and“cradle-to-gate”as the system boundary.Based on the baseline scenario,a natural gas generator set was added to replace central heating,and the light pipes were expanded to constitute the optimized scenario.The results showed that the key impact categories for both scenarios were global warming,fine particulate matter formation,human carcinogenic toxicity,and human non-carcinogenic toxicity.The overall environmental impact of the optimized scenario was reduced by 68%compared to the baseline scenario.A sensitivity analysis of the key factors showed that electricity from the power grid was the key impact factor in both scenarios,followed by central heating and natural gas.Therefore,to reduce the environmental impact of network systems,it is necessary to further optimize the grid power structure.The research approach can be used to optimize micro-energy networks and evaluate the environmental impact of different energy systems.

高管股权激励、管理层短视主义与企业金融化

近年来,中国经济在高速增长的同时出现了“脱实向虚”的现象,越来越多的实体企业脱离传统主营业务,将大量资金投资于金融市场,导致金融资产的配置规模越来越大,实体企业对金融投资收益的依赖性越来越高,造成了较为严重的实体企业金融化现象。高管作为企业生产经营的重要决策者,对企业金融资产的置配有着重要影响。选取2010-2020年沪深A股上市公司数据,实证分析高管股权激励对企业金融化的影响机制。研究发现,高管股权激励可有效抑制企业金融化,管理层短视主义在二者间发挥了部分中介作用。异质性分析发现,高管股权激励抑制企业金融化的效果在高融资约束、高管无金融教育背景的企业中更为显著。因此,企业应优化高管股权激励制度,不断提升主业盈利能力,重视高管的金融教育背景;政府应通过各种政策手段改善融资环境,帮助减少企业融资成本。

Carbon footprint accounting for cigar production processes: A life cycle assessment perspective

Although the tobacco industry is a significant contributor to energy consumption and carbon emissions its negative environmental impact has received inadequate attention globally.Cigarette factories are a key link in the tobacco industry’s production chain,and using data provided by a cigarette factory in China we conduct a life cycle assessment to account for the carbon footprint of cigar production in cigarette factories.The results of the assessment show that factory air conditioning is the most important contributor to the environmental load of the cigar manufacturing process,while electricity is the key factor that contributes the greatest envi‐ronmental load across all of the processes in the product life cycle.In addition,packaging,including small boxes and cigarette cartons,has a significant impact on the industry’s environmental footprint due to its use of raw materials.We find the carbon footprint of the entire production process for cigar products to be 383.59 kg CO_(2) eq.Based on our findings,we suggest ways to optimize cigar/cigarette factory processes to re‐duce carbon emissions that can help to promote sustainable development in related industries.

基于网络自主学习平台的教学实践探索—以东北林业大学为例

随着信息技术的发展,充分利用多媒体和网络技术改进以教师讲授为主的单一课堂教学模式已经成为高等教育教学和改革的方向。通过实际教学及问卷调查,发现平台使用两年来,教师和学生可以利用站内短信、邮件、论坛等就与课程学习相关的一系列活动进行交流和互动,实现学生的自主学习和学生、教师之间的交互学习,从而满足学生、教师学习、教学的实际需求。同时,也出现了一些问题,需要在实践中不断摸索加以改进。

Lineage tracing of direct astrocyte-to-neuron conversion in the mouse cortex

Regenerating functional new neurons in the adult mammalian central nervous system has been proven to be very challenging due to the inability of neurons to divide and repopulate themselves after neuronal loss.Glial cells,on the other hand,can divide and repopulate themselves under injury or diseased conditions.We have previously reported that ectopic expression of NeuroD1 in dividing glial cells can directly convert them into neurons.Here,using astrocytic lineage-tracing reporter mice(Aldh1l1-CreERT2 mice crossing with Ai14 mice),we demonstrate that lineage-traced astrocytes can be successfully converted into NeuNpositive neurons after expressing NeuroD1 through adeno-associated viruses.Retroviral expression of NeuroD1 further confirms that dividing glial cells can be converted into neurons.Importantly,we demonstrate that for in vivo cell conversion study,using a safe level of adeno-associated virus dosage(10^10–10^12 gc/mL,1μL)in the rodent brain is critical to avoid artifacts caused by toxic dosage,such as that used in a recent bioRxiv study(2×10^13 gc/mL,1μL,mouse cortex).For therapeutic purpose under injury or diseased conditions,or for non-human primate studies,adeno-associated virus dosage needs to be optimized through a series of dose-finding experiments.Moreover,for future in vivo gliato-neuron conversion studies,we recommend that the adeno-associated virus results are further verified with retroviruses that mainly express transgenes in dividing glial cells in order to draw solid conclusions.The study was approved by the Laboratory Animal Ethics Committee of Jinan University,China(approval No.IACUC-20180330-06)on March 30,2018.

The efficiency and toxicity of dodecafluoro-2-methylpentan-3-one in suppressing lithium-ion battery fire

Currently,the effective and clean suppression of lithium-ion battery(LIB)fires remains a challenge.The present work investigates the use of various inhibitor doses(Xin)of dodecafluoro-2-methylpentan-3-one(C_(6) F_(12)O)in 300 Ah LIBs,and systematically examines the thermal and toxic hazards of the extinguished batteries via real scale combustion and gas analysis.The inhibitor is shown to be completely effective.The inhibition mechanism involves a combination of chemical inhibition and physical cooling.While the chemical inhibition effect tends to saturate with increasing Xin,the physical cooling remains effective at higher inhibitor doses.However,extinguishing the battery fire with a high Xin of C_(6)F_(12)O is found to incur serious toxicity problems.These results are expected to provide a guideline for the design of inhibitor doses for the suppression of LIB fires.

Insight into the structural evolution and thermal behavior of LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode under deep charge

By virtue of the crucial effect of the crystal structure and transition metal(TM)redox evolution on the performance of LiNi_(x)Co_(y)Mn_(z)O_(2)(NCM)cathode,systematical investigation is carried out to better understand the charge mechanism upon deep charging.Based on the results of X-ray diffraction and highresolution transmission electron microscope,phase transformations existing on particle surface are promoted by high potential because of the deeper lithium vacancies,accompanied by more substantial structure instability.Soft X-ray absorption spectroscopy indicates that Ni acts as the major contributor to charge compensation while Co displays a remarkable redox activity over the deep charge range.The elevated integrated intensity of pre-edge in O K-edge spectra reveals the extensive amount of holes formed in O 2 p orbitals and the enhanced hybridization of TM 3 d-O 2 p orbitals.Considering the close relationship between thermal behavior and structural evolution,the tendency of phase transitions and O_(2) release upon heating is accelerated by voltage rise,demonstrating the aggravated instability due to deeper Li utilization.Remaining Li contents in NCM are employed to estimate the amount of oxygen released in structural transformation and its detrimental effect on stability declares Li contentdependent characteristics.Furthermore,the extended Li vacancies,higher proportion of Ni4+and stronger orbital hybridization are considered as three factors impeding the thermal stability of the highlydelithiated NCM.

High entropy fluorides as conversion cathodes with tailorable electrochemical performance

With the recent development of high entropy materials, an alternative approach to develop advanced functional materials with distinctive properties that show improved values compared to conventional materials has been provided. The high entropy concept was later successfully transferred to metal fluorides and high entropy fluorides(HEFs) were successfully synthesized. Owing to their high theoretical specific capacities in energy storage applications, HEFs were utilized as cathode materials for lithiumion batteries(LIBs) and their underlying storage mechanisms were investigated. Instead of a step-bystep reduction of each individual metal cation, the HEFs seem to exhibit a single-step reduction process,indicating a solid solution compound instead of merely a mixture of different metal fluorides. It was also observed that the electrochemical behavior of the HEFs depends on each individual incorporated element. Therefore, by altering the elemental composition, new materials that exhibit improved electrochemical properties can be designed. Remarkably, HEFs with seven incorporated metal elements exhibited a better cycling stability as well as a lower hysteresis compared to binary metal fluorides.These findings offer new guidelines for material design and tailoring towards high performance LIBs.

Precise in-situ and ex-situ study on thermal behavior of LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)/graphite coin cell:From part to the whole cell

Multiple mode calorimetry and C80 micro-calorimeter are used to investigate the impact of cathode and anode on heat generation of lithium ion battery.The thermal behaviors of LiNi_(x)Co_(y)Mn_(z)O_(2)/graphite full cell are discussed under normal operating and elevating temperature.Affected by negative entropy change,lithium intercalation presents more exotherms than deintercalation for both electrode materials.The contributions of irreversible and reversible heat to the total heat generation of graphite are evaluated.The phase transitions correlated with voltages and lithium contents are determined.Based on the analysis of half-cell,the effect of two electrodes(with the same capacity)on overall heat generation is nearly the same and anode of full cell plays a key role in charging while cathode dominates in discharging.Thermal behaviors of lithiated graphite and delithiated LiNi_(x)Co_(y)Mn_(z)O_(2) electrolyte and their coexisting system are identified to further explore their influence on battery safety.The breakdown of solid electrolyte interface(SEI)at around 82℃ is considered as a crucial factor affecting the thermal stability of full cell.The oxidation of electrolyte induced by oxygen released from cathode material turns out to be one of the main heat sources.These accurate results are of great significance to improve the existing thermal management system and provide basic data for the prediction of battery performance.

Transition-metal redox evolution and its effect on thermal stability of LiNixCoyMnzO_(2) based on synchrotron soft X-ray absorption spectroscopy

Based on the synchrotron soft X-ray absorption spectroscopy experiments,the fundamental electronic structures of layered Li NixCoyMnzO_(2)(NCM)are investigated systematically and the data of transitionmetal(TM)L-and O K-edges spectra are collected.Distribution of Ni ions under different oxidation states is evaluated according to linear combination fit.It is found that the ratio of Ni^(4+)expands with the increase of Ni since it dominates in charge compensation during charging,and that the existence of Ni^(3+)is nearly negligible in delithiated NCM.The valence state of Co also strongly depends on Ni content,the perceptible position shift of Co L_(3)-edge absorption peak towards higher energy in Ni-rich material agrees well with the small voltage plateau at around 4.2 V.The stability of Mn is verified as no obvious spectral change with the Mn L-edge is observed.Moreover,as Ni content rises,the O 2p holes near the Femi level increases with higher oxidation state of Ni,indicating the enhanced hybridization of O 2p-TM 3 d.Delithiated NCMs with higher Ni content are prior to lose electron existing in highly hybridized Ni3 dO 2 p bands upon heating,which accounts for the pronounced O_(2)release in phase transitions and the deterioration in thermal stability.These detailed observation of the electronic structure evolution is one of the key ingredients to improving the electrochemical and thermal performance of NCM.

Optimization of energy consumption structure based on carbon emission reduction target:A case study in Shandong Province,China

It is urgent to significantly reduce greenhouse gas emissions to actively deal with global warming.This paper investigates Shandong Province,a typical province of energy consumption,as the research object,aiming to optimize total energy consumption and consumption structure in the future planning year.This paper constructs a methodological system to optimize energy consumption structure in Shandong Province,using a scenario combination of system dynamics(SD)prediction and analysis based on the coupling of key scenario elements affecting different energy consumption from different perspectives.Structural equation modeling and SD sensitivity analysis indicate an overlap between key factors restricting energy consumption.Pairing the key scenario factors can better reflect the internal mechanism of energy consumption development.Based on this,21 scenarios based on different combinations of the key elements are constructed.Through SD prediction and analysis,the most suitable scenario mode for optimizing energy consumption structure in Shandong Province is selected.This paper provides a suitable development range for the average gross domestic product growth rate,the proportion of secondary industry,energy consumption intensity of secondary industry,and the urbanization rate for Shandong Province.This paper can provide a reference for similar research and the government in formulating the optimization scheme of energy consumption structure.

Correlating electrochemical performance and heat generation of Li plating for lithium-ion battery with fluoroethylene carbonate additive

1.Introduction With the superior performance of high energy density,lightweight and long life span,lithium-ion battery(LIB)are perceived as an attractive and reliable power source for modern-used portable electronics,ecofriendly electric vehicles and power distribution,and thereby a remarkable solution to assuage energy dependence on fossil fuel and environmental concern.Nevertheless,the unexpected Li plating together with the Li dendrites growth on graphite anode surface has been a profound hindrance to the practical application of LIB,of which induces inferior Coulombic efficiency,poor lifespan and safety concern[1].

Comprehensive emergy evaluation and optimization of corn straw power generation system: a case study

Biomass energy has become an important measure to alleviate ecological environment security and energy supply security in China.Emergy accounting method is used to analyze and evaluate economy,environment,and sustainability of corn straw generation system,which includes corn planting subsystem,collection and transportation subsystem,and corn straw power generation subsystem.The key substances that need to be optimized in the system are identified by using sensitivity analysis.Based on the position of key substances in the system,emergy accounting optimization methodology is conducted.Corresponding optimization design scheme is proposed based on the '3R' (reduce,reuse,and recycle) principle of circular economy.Current study shows that emergy yield ratio,emergy investment ratio,environmental loading ratio,and emergy sustainability index of the corn straw power generation system are 3.69,2.68,1.61,and 2.29,respectively,which are better than wind power generation system and thermal power generation system.In addition,it is proposed that the fertilizer alternative plan and the transportation redesign plan can replace 50,000 tons potash and reduce equipment resources by 20% and energy resources input by 30%.Economy and sustainable development of the system is significantly improved.The optimization design method based on the '3R' principle proposed in this paper can provide a useful reference for the research in the field of resource recycling.

Evaluation and advancement of the integrated circular economy model of farming and stock raising

The integrated circular economy model of farming and stock raising(ICEMFSR)has attracted increased attention as an effective model for solving the current irrational allocation of agricultural resources and realizing the agricultural value-added industrial chain.This study uses emergy analysis to comprehensively examine and evaluate the economic benefits,environmental pressures,and sustainable development levels of ICEMFSR in Shucheng County,China.The results show that the ICEMFSR possesses the value of popularization with optimally allocated resources in the studied region,in which the emergy yield ratio(EYR),emergy loading ratio(ELR),and emergy sustainable index(ESI)in this model accounted for 3.59,1.25,and 2.89,respectively.This result indicates a leading position in the national agricultural system.Hence,this study constructs a new model based on the coupling of emergy evaluation and multi-objective linear programming to study ICEMFSR.Consequently,the EYR,ELR,and ESI respectively varied by +24.23%,10.40%,and +38.06%after replanning of ICEMFSR.This variation implies a significant improvement in the sustainable development level of the model.In addition,the optimized scenario design for key substances is proposed based on traceability and the reduce-reuse-recycle principle,including biogasification of crop straw and enhancement of crop scientific planting capacity.

Effects of Angelica Polysaccharide on telomere length in mice with benzene-induced aplastic anemia

Objective:To investigate the changes in telomere length and the level of burst-forming units-erythrocyte(BFU-Es)and colony-forming unit-erythrocytes(CFU-Es)in mice with benzene-induced aplastic anemia(AA),and follow-up the therapeutic effects of Angelica Polysaccharide(AP).Methods:Male BALB/c mice(n=120)were randomly divided into three groups(1,2,3):normal control(n=24),AA control(n=48),and treated AA(n=48),respectively.Mice in Group 2 received benzene inhalation for 2.5 months and 1 ml distilled water p.o.per day for 2 weeks after the establishment of AA models.Similar procedure was applied to the mice in Group 3 and AP was given for 2 weeks after the establishment of AA models.Real-time polymerase chain reaction was used to survey relative telomere length measurement of the bone marrow cells.A BFU-Es and CFU-Es survey was done to follow-up the therapeutic effects of AP.Results:Compared with normal control,significant reductions of RBC,WBC,and platelet counts were found in peripheral blood of AA mice.After treatment with AP,counts of BFU-Es and CFU-Es were restored up to 66.8%and 77.25%,respectively,and length of telomere was restored up to 76.34%,of the normal levels.The telomere length in treated AA group was higher than the control AA group.Conclusion:The AP can protect the telomere length and differentiation of hemopoietic stem/progenitor cells,accelerate the recovery of BFU-Es and CFU-Es of AA mice,and then improve the bone marrow failure.

A dynamic interaction assessment method for disaster management based on extended DEMATEL

With the frequent occurrence of various disasters,serious damage has been caused to social and economic development.Therefore,disaster management plays an increasingly significant role in controlling disasters and reducing losses.This study aims to provide a dynamic interaction assessment method for the emergency management department to manage disasters.For this purpose,the classical Decision-Making Trial and Evaluation Laboratory(DEMATEL)method is first extended with bipolar 2-tuple linguistic information to model both the negative and positive influences among factors involved in coping with disaster.Then,the weights of influential factors are determined according to their total interaction relationships derived by extended DEMATEL.After that,the performances or states of factors are suggested to be appraised under a bipolar 2-tuple linguistic environment.Further,the performance or state simulation rule of factors is proposed based on their initial states and the interactions among them during disaster management.According to the simulation results,a weighted average operator is employed to obtain the overall performance values of emergency scenarios.Finally,an illustrative example and comparative analysis are presented for elucidating the feasibility and usefulness of the suggested method.Results of a case study show that the proposed method has the abilities to capture the interactions among influential factors and explore how the factors and their interactions affect disaster management.The proposed method could provide valuable information to emergency management departments for managing disasters more effectively.