Advances in sodium-ion batteries at low-temperature: Challenges and strategies

With the continuing boost in the demand for energy storage,there is an increasing requirement for batteries to be capable of operation in extreme environmental conditions.Sodium-ion batteries(SIBs) have emerged as a highly promising energy storage solution due to their promising performance over a wide range of temperatures and the abundance of sodium resources in the earth's crust.Compared to lithiumion batteries(LIBs),although sodium ions possess a larger ionic radius,they are more easily desolvated than lithium ions.Fu rthermore,SIBs have a smaller Stokes radius than lithium ions,resulting in improved sodium-ion mobility in the electrolyte.Nevertheless,SIBs demonstrate a significant decrease in performance at low temperatures(LT),which constrains their operation in harsh weather conditions.Despite the increasing interest in SIBs,there is a notable scarcity of research focusing specifically on their mechanism under LT conditions.This review explores recent research that considers the thermal tolerance of SIBs from an inner chemistry process perspective,spanning a wide temperature spectrum(-70 to100℃),particularly at LT conditions.In addition,the enhancement of electrochemical performance in LT SIBs is based on improvements in reaction kinetics and cycling stability achieved through the utilization of effective electrode materials and electrolyte components.Furthermore,the safety concerns associated with SIBs are addressed and effective strategies are proposed for mitigating these issues.Finally,prospects conducted to extend the environmental frontiers of commercial SIBs are discussed mainly from three viewpoints including innovations in materials,development and research of relevant theoretical mechanisms,and intelligent safety management system establishment for larger-scale energy storage SIBs.

A review on ignition mechanisms and characteristics of magnesium alloys

Magnesium alloys have become more attractive because of their low density and electromagnetic shielding effectiveness in the aerospace industry.However,some unpredictable situation may lead to the ignition of magnesium alloys.In this review,the thermodynamic conditions and transfer processes of magnesium alloys ignition are analyzed from the point of mechanisms.The criteria of ignition are emphasized.In addition,ignitability and flammability test systems are compared.And a more suitable method to assess the potential ignition and flammability risks of magnesium alloys in extreme environments is recommended.Furthermore,the ignition characteristics of magnesium alloys are discussed in detail.It was found that the ignition of magnesium alloys is a complex process determined by internal properties such as thermo-physical properties,oxide film properties,chemical compositions and geometrical parameters,as well as the external environment such as gas species,oxygen concentration and oxygen pressure.Ignition temperature is not physical constants of materials.It is not simply assumed that ignition may occur when the temperature of Mg alloys reaches a certain ignition point.Finally,the unsolved issues in the ignition of magnesium alloys are pointed out and the future investigation are suggested for improving the safety and reliability of magnesium alloys in the aerospace applications.

A geometric model of faulted detachment folding with pure shear and its application in the Tarim Basin, NW China

We present an improved geometric model of faulted detachment folding with pure shear that is characterized by core thickening and a ramp-discordant backlimb. The model includes a two-stage evolution： 1） detachment folding involving pure shear with fixed hinges, and 2） faulted detachment folding, in which the core of anticline thrusts above a break-through fault in forelimb by limb rotation. The growth strata patterns of the model are also discussed with respect to factors such as limb rotation, tectonic uplift rate, and sedimentation rate. A thrust-related fold, called a TBE thrust fold, in the Tarim Basin in NW China, is analyzed as an example of the theoretical model. The result indicates that the TBE thrust fold has undergone a two-stage evolution with shortening of a few hundred meters. Both the theoretical model and the actual example indicate that the shortening in the detachment folding stage takes up a large proportion of the total shortening. The structural restoration of the TBE thrust fold also provides new evidence that the formation of a series of thin-skinned structures in the SE Tarim Basin initiated in the Late Ordovician. The model may be applicable to low-amplitude faulted detachment folds.

Water-induced hydrogenation of graphene/metal interfaces at room temperature:Insights on water intercalation and identification of sites for water splitting

Though it is well recognized that the space between graphene cover and the metal substrate canact as a two-dimensional(2D)nanoreactor,several issues are still unresolved,including the role of the metal substrate,the mechanisms ruling water intercalation and the identification ofsites at which water is decomposed.Here,we solve these issues by means of density functional theory and high-resolution electron energyloss spectroscopy experiments carried out on graphene grown on(111)-oriented Cu foils.Specifically,we observe decomposition of H2O atroom temperature with only H atoms forming bonds with graphene and with buried OH groups underneath the graphene cover.Ourtheoretical model discloses physicochemical mechanisms ruling the migration and decomposition of water on graphene/Cu.We discover thatthe edge of graphene can be easily saturated by H through decomposition of H2O,which allows H2O to migrate in the subsurface region from thedecoupled edge,where H2O decomposes at room temperature.Hydrogen atoms produced by the decomposition of H2O initially form a chemicalbond with graphene for the lower energy barrier compared with other routes.These findings are essential to exploit graphene/Cu interfaces incatalysis and in energy-related applications.

后合成静电吸附辅助制备高效Fe-N-C单原子氧还原催化剂用于锌-空气电池

设计和制备高效的非铂族催化剂对锌-空气电池的大规模应用至关重要.本文采用简单的后合成静电吸附策略制备了Fe-N-C单原子催化剂(Fe-SA/N-C).其中,Fe原子与相邻的氮原子形成Fe-N4活性位点并锚定在三维多孔碳上.该催化剂在0.1 mol L^(-1)KOH (E_(1/2)=0.92 V)和0.5 mol L^(-1)H_(2)SO_(4)(E_(1/2)=0.77 V)中均表现出优异的氧化还原活性,性能优于商业Pt/C催化剂(0.1 mol L^(-1)KOH,E_(1/2)=0.85 V;0.5 mol L^(-1)H_(2)SO_(4),E_(1/2)=0.79 V).此外,以Fe-SA/N-C作为阴极催化剂自组装的液体锌-空气电池具有优异的放电比容量和峰值功率密度,优于商业Pt/C催化剂.密度泛函理论计算结果表明,石墨化氮掺杂的Fe-N4位点能有效提高ORR中间产物的活化程度,降低速率决定步骤的能垒.本工作对非铂族催化剂的实验制备和理论研究提出了新的见解,为锌-空气电池中使用的非铂族催化剂的合理设计提供了一般策略.

MOF衍生的单原子催化剂中γN原子在ORR反应中的远程作用及其调制机制

燃料电池的发展有助于促进“双碳”目标的早日实现,但其阴极氧还原反应(ORR)的多步质电耦合传输机制导致其动力学过程缓慢.目前,金属有机框架材料衍生的单原子催化剂(SACs)因具有较高的ORR催化活性而被认为是一种优势燃料电池阴极材料.然而,由于SACs活性位点的外层结构难以精确表征,因此相关催化反应机制尚不明确.鉴于此,本研究着眼第三配位层γN原子对其邻近βC原子位点和活性金属中心的双重影响开展了深入研究.结果表明,不同位置和数量的γN掺杂会改变Fe–N_(4)/C–γN_(x)结构中被取代C位点的电子结构,从而影响邻近金属中心的βC原子电荷分布.同时,这些变化还将通过长程效应间接影响金属中心的电子分布及自旋,从而增强4e−反应路径的ORR性能.更重要的是,电负性增强的βC原子更容易吸附OH基团,因此使得γN掺杂的Fe–N_(4)/C–γN_(x)具备更加优异的碱性环境ORR理论性能.基于以上结果,我们还发现γN调制的βC辅助ORR路径具有比常规4e−反应路径更低的过电势.本研究针对决速步的波函数分析促进了从电子层次对该反应作用机制的理解,揭示了该类单原子催化剂中γN位点精确设计和表征的重要意义.

Single-atom Co-N_(4)catalytic sites anchored on N-doped ordered mesoporous carbon for excellent Zn-air batteries

Developing efficient transition metal-nitrogen-carbon(TM-N-C)catalysts with abundant accessible active sites has been in the limelight in recent years due to their exceptional application potential in Zn-air bat-teries(ZABs).Herein,we report the simple and environmentally-friendly fabrication of a single-atom Co electrocatalyst,Co-SA/N-C_(900),via in-suit pyrolysis of the co-precursor containing sucrose,dicyandiamide,and Co salts.The Co single atoms coordinated with adjacent N atoms are anchored on the doped ordered mesoporous carbon,generating the atomic Co-N_(4)moiety.Co-SA/N-C_(900)displays high oxygen reduction reaction(ORR)activity with an onset potential of 0.96 V and a half-wave potential of 0.87 V.Notably,the liquid ZAB with Co-SA/N-C_(900)catalyst exhibits exceptional discharge specific capacity of 706.38 mAh g^(-1),peak power density of 191.11 mW cm^(-2),and excellent stability at high current densities up to 100 mA cm^(-2),surpassing commercial Pt/C.According to the density functional theory(DFT)study,the Co-N_(4)moi-ety with graphitic N dopants can decrease the rate-determining step(RDS)energy barrier and thus accel-erate the ORR process.This study offers experimental and theoretical guidelines for the rational design of TM-N-C catalysts for practical implementation with notable ORR activity for application in ZABs.

Corrosion mechanism investigation of TiN/Ti coating and TC4 alloy for aircraft compressor application

It is imperative to develop multifunctional erosion and corrosion resistant coatings for compressor blades of aircraft engines in harsh environment.PVD(Physical Vapor Deposition)technology has the advances in processing erosion-resistant coatings;however,the performance of PVD coatings to combat corrosion depends on various coating defects.Determining and comparing the corrosion performances of PVD TiN/Ti coating and uncoated TC4 alloy was the main objective of present work.The 960 h salt spray corrosion and 116 h hot corrosion tests were conducted to simulate the grounding and working environments of the aircraft compressors.The corrosion mechanisms due to the coating defects such as pinhole,columnar boundary and large grain were analyzed based on the OM,Confocal microscope,electrochemical measurements,SEM,XRD and EDS results.Owing to the disordered state associated with the columnar boundary and the coating defect,nitrogen could be easily replaced by oxygen in the hot corrosion process,these structures were channels for fast diffusion of oxygen.Moreover,the Gibbs energy changes of Ti oxidation and TiN oxidation were thermodynamically calculated according to the working condition of aircraft compressors,and considerable research effort was focused on mapping out the phase diagram of Ti,TiN and high pressure gases.The findings of this research can provide insights into developing multifunctional coatings for future aircraft engines.

Characterization and Trading of Energy Level and Energy Shift Considering Virtual Power Plant

The capability of shifting the electricity generation or consumption to proper time of the day,also defined as energy shift(ES),is the key factor to ensure the power balance,especially under high penetration of variable renewable energy(VRE).However,the ES is not characterized and traded as an independent product in current market mechanisms.In this letter,the marginal utility of an ES is assessed and leveraged to characterize the effective ES,while a novel market scheme is proposed considering the trading of both ES and energy level(EL).The proposed scheme can well integrate ES producers such as virtual power plants that cannot be rewarded sufficiently to actively participate in the current market because they are principally labeled as EL consumers.Finally,the novel concept and mechanism are illustrated by a numerical study and verified to outperform the existing price schemes on integrating the ES resources and VRE.

Optimal power flow calculation in AC/DC hybrid power system based on adaptive simplified human learning optimization algorithm

This paper employs an efficacious analytical tool,adaptive simplified human learning optimization(ASHLO)algorithm,to solve optimal power flow(OPF)problem in AC/DC hybrid power system,considering valve-point loading effects of generators,carbon tax,and prohibited operating zones of generators,respectively.ASHLO algorithm,involves random learning operator,individual learning operator,social learning operator and adaptive strategies.To compare and analyze the computation performance of the ASHLO method,the proposed ASHLO method and other heuristic intelligent optimization methods are employed to solve OPF problem on the modified IEEE 30-bus and 118-bus AC/DC hybrid test system.Numerical results indicate that the ASHLO method has good convergent property and robustness.Meanwhile,the impacts of wind speeds and locations of HVDC transmission line integrated into the AC network on the OPF results are systematically analyzed.

Analysis of Dynamic Appliance Flexibility Considering User Behavior via Non-intrusive Load Monitoring and Deep User Modeling

The research on non-intrusive load monitoring(NILM)and the growing deployment of home energy manage-ment system(HEMS)have made it possible for households to have a detailed understanding of their power usage and to make appliances participate in demand response(DR)programs.Appliance flexibility analysis helps the HEMS dispatching appli-ances to participate in DR programs without violating user’s comfort level.In this paper,a dynamic appliance flexibility analysis approach using the smart meter data is presented.In the training phase,the smart meter data is preprocessed by NILM to obtain user’s appliances usage behaviors,which is used to train the user model.During operation,the NILM is used to infer recent appliances usage behaviors,and then the user model predicts user’s appliances usage behaviors in the DR period considering long-term behaviors dependences,correlations between appliances and temporal information.The flexibility of each appliance is calculated based on the appliance characteristics as well as the predicted user’s appliances usage behaviors caused by the control of the appliance.The HEMS can choose the appliance with high flexibility to participate in the DR programs.The case study demonstrates the performance of the user model and illustrates how the appliance flexibility analysis is performed using a real-world case.

濒危植物大别山五针松根际细菌群落特征与功能分析

植物根际微生物群落对植物健康生长有重要影响,每种植物根际都有其特定的微生物群落。大别山五针松(Pinus dabeshanensis)被国际自然保护联盟列为濒危物种,具有重要研究价值。该研究采用16S rRNA高通量测序技术与生物信息学方法,对濒危植物大别山五针松根际细菌群落特征与功能进行分析。结果表明,大别山五针松根际微生物的主要种类为变形菌门、放线菌门、酸杆菌门和疣微菌门。网络分析表明,大别山五针松根际细菌类群存在显著相关性,其中Bryobacter属、Bradyrhizobium属和未定义的TK10属是互作网络中的重要节点。PICRUSt1功能预测表明其微生物组功能主要为氨基酸运输和代谢、细胞壁/膜/膜生物发生以及能量产生和转换。FAPROTAX功能预测表明,大别山五针松根际富含的优势菌群具有丰富的化学异养、纤维素水解、需氧化学异养和固氮功能,其对植物生长发育具有重要作用。研究结果可为培育健康的大别山五针松根际微生物菌群及微生物资源的开发利用提供重要依据。

Classification of Soft Tissue Sarcoma Specimens with Raman Spectroscopy as Smart Sensing Technology

Intraoperative confirmation of negative resection margins is an essential component of soft tissue sarcoma surgery.Frozen section examination of samples from the resection bed after excision of sarcomas is the gold standard for intraoperative assessment of margin status.However,it takes time to complete histologic examination of these samples,and the technique does not provide real-time diagnosis in the operating room(OR),which delays completion of the operation.This paper presents a study and development of sensing technology using Raman spectroscopy that could be used for detection and classification of the tumor after resection with negative sarcoma margins in real time.We acquired Raman spectra from samples of sarcoma and surrounding benign muscle,fat,and dermis during surgery and developed(i)a quantitative method(QM)and(ii)a machine learning method(MLM)to assess the spectral patterns and determine if they could accurately identify these tissue types when compared to findings in adjacent H&E-stained frozen sections.High classification accuracy(>85%)was achieved with both methods,indicating that these four types of tissue can be identified using the analytical methodology.A hand-held Raman probe could be employed to further develop the methodology to obtain spectra in the OR to provide real-time in vivo capability for the assessment of sarcoma resection margin status.