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Understanding the sluggish and highly variable transport kinetics of lithium ions in LiFePO_4

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Science China Chemistry 2023年第11期66卷 3297-3306页

作者： youcheng hu Xiaoxiao Wang Peng Li Junxiang Chen Shengli Chen hubei Electrochemical Power Sources Key Laboratory Department of ChemistryWuhan UniversityWuhan 430072China CAS Key Laboratory of Design and Assembly of Functional Nanostructures Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China

LiFePO_(4),one of the mainstream cathode materials of current EV batteries,exhibits experimental diffusion coefficients(D_(c))of Li^(+)which are not only several orders of magnitude lower than those predicted by the ionic hopping barriers obtained from theoretical calculations and spectroscopic measurements,but also span several orders from 10^(-14)to 10^(-18)cm^(2)s^(-1)under different states of charge(SOC)and the charging rates(C-rates).Atomic level understanding of such sluggishness and diversity of Li^(+)transport kinetics would be of significance in improving the rate performance of LiFePO_(4)through material and operation optimization but remain ***,we show that the high sensitivity of Li^(+)hopping barriers on the local Li–Li coordination environments(numbers and configurations)plays a key role in the ion transport *** is due a neural network-based deep potential(DP)which allows accurate and efficient calculation of hopping barriers of Li^(+)in LiFePO_(4)with various Li–Li coordination environments,with which the kinetic Monte-Carlo(KMC)method was employed to determine the D_(c)values at various C-rates and SOC across a broad ***,an accelerated KMC simulation strategy is proposed to obtain the D_(c)values under a wide range of SOC at low C-rates,which agree well with that obtained from the galvanostatic intermittent titration technique(GITT).The present study provides accurate descriptions of Li^(+)transport kinetics at both very high and low C-rates,which remains challenging to experiments and first-principles calculations,***,it is revealed that the gradient distributions of Li^(+)density along the diffusion path result in great asymmetry in the barriers of the forward and backward hopping,causing very slow diffusion of Li^(+)and the diverse variation of D_(c).

关键词： lithium iron phosphate diffusion coefficient machine-learning potential kinetic Monte Carlo simulations

A combinatorial descriptor for volcano relationships of electrochemical nitrogen reduction reaction

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Chinese Journal of Catalysis 2022年第11期43卷 2881-2888页

作者： Ziyi Jiang youcheng hu Jun huang ShengLi Chen hubei Electrochemical Power Sources Key Laboratory Department of ChemistryWuhan UniversityWuhan 430072HubeiChina Institute of Energy and Climate Research(IEK-13) Forschungszentrum JülichWilhelm-Johnen-Straße52425 JülichGermany

Though touted as a potential way to realize clean ammonia synthesis,electrochemical ammonia synthesis is currently limited by its catalytic *** effort has been made to find catalysts with improved activity toward electrochemical nitrogen reduction reaction(eNRR).Rational screening of catalysts can be facilitated using the volcano relationship between catalytic activity and adsorption energy of an intermediate,namely,the activity *** this work,we proposeΔG^(*)_(NH_(2))+ΔG^(*)_(NNH)as a combinatorial descriptor,which shows better predictive power than traditional descriptors using the adsorption free energies of single *** volcano plots based on the combinatorial descriptor exhibits peak activity fixedly at the descriptor value corresponding to the formation free energy of NH3,regardless of the catalyst types;while the descriptor values correspond to the top activities for eNRR on volcano plots based on single descriptors usually vary with the types of catalysts.

关键词： Electrocatalysis Electrochemical nitrogen reduction reaction Single atom catalyst Single cluster catalyst Scaling relationship

Dynamics and vibration reduction performance of asymmetric tristable nonlinear energy sink

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 389-406页

作者： Hongyan CHEN youcheng ZENG hu DING Siukai LAI Liqun CHEN School of Mechanical Engineering University of Science and Technology BeijingBeijing 100083China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsShanghai Institute of Applied Mathematics and MechanicsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200444China Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina

With its complex nonlinear dynamic behavior,the tristable system has shown excellent performance in areas such as energy harvesting and vibration suppression,and has attracted a lot of *** this paper,an asymmetric tristable design is proposed to improve the vibration suppression efficiency of nonlinear energy sinks(NESs)for the first *** proposed asymmetric tristable NES(ATNES)is composed of a pair of oblique springs and a vertical ***,the three stable states,symmetric and asymmetric,can be achieved by the adjustment of the distance and stiffness asymmetry of the oblique *** governing equations of a linear oscillator(LO)coupled with the ATNES are *** approximate analytical solution to the coupled system is obtained by the harmonic balance method(HBM)and verified *** vibration suppression efficiency of three types of ATNES is *** results show that the asymmetric design can improve the efficiency of vibration reduction through comparing the chaotic motion of the NES oscillator between asymmetric steady *** addition,compared with the symmetrical tristable NES(TNES),the ATNES can effectively control smaller structural *** other words,the ATNES can effectively solve the threshold problem of TNES failure to weak ***,this paper reveals the vibration reduction mechanism of the ATNES,and provides a pathway to expand the effective excitation amplitude range of the NES.

关键词： asymmetric nonlinear energy sink(NES) tristable vibration control po-tential barrier

A potential-driven switch of activity promotion mode for the oxygen evolution reaction at Co_(3)O_(4)/NiO_(x)H_(y) interface

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eScience 2022年第4期2卷 438-444页

作者： Wang Wang Zixu Wang youcheng hu Yucheng Liu Shengli Chen Electrochemical Power Sources Key Laboratory Department of ChemistryWuhan UniversityWuhan430072China Wuhan University Testing Center Wuhan UniversityWuhan430072China

Co_(3)O_(4)spinel oxides have manifested promising activity toward the oxygen evolution reaction(OER)through effective *** them to become top electrocatalysts,however,accurate accounts of the catalytic kinetics are essential to gain a deep understanding of the activity promotion ***,we use a newly proposed kinetic model based on energetic span as the rate-determining term for the electrocatalytic reaction to throw light on the promotion mechanism of Co_(3)O_(4)interfaced with nickel hydroxides(NiO_(x)H_(y))for the *** find that depending on the electrode potential,the OER kinetics at the designed interface between Co_(3)O_(4)and NiO_(x)H_(y)are boosted in entirely different *** a result,the OER can occur at a lower onset potential as well as a low Tafel *** work emphasizes the benefit of using rational theoretical models for electrocatalyst design.

关键词： Oxygen evolution reaction Interface engineering Double exchange interaction Potential-driven switch of mechanism Energetic span

Space truss construction modeling based on on-orbit assembly motion feature

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Chinese Journal of Aeronautics 2024年第3期37卷 365-379页

作者： Changjie ZHAO Weizhong GUO Meng CHEN Jiaxing hu youcheng HAN Rongfu LIN State Key Lab of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai 200240China Institute of Aerospace System Engineering Shanghai Shanghai 201109China

More space truss construction has been planned to develop and utilize space *** trusses are designed in the way of large-scale,complex,modular,and on-orbit *** meet the upcoming challenge of large-scale space infrastructure construction,it is necessary to study space truss automation design and robotic *** paper proposes an ordinal finite screw adjacency matrix model(OFSAMM),focusing on the relationship between assembly motions,to express and compute a space truss *** this model,a space truss is abstracted as a set of ordered assembly motions,each of which is recorded as a finite screw as the basic element of the truss and its *** operation of truss transformation is also derived under this ***,the truss configuration,the assembly sequence,the truss sub-assembly,the truss components,and the on-orbit assembly task can be expressed and calculated in a unified model,which is calculated and stores the truss topology and assembly with the minimum storage *** the end of this paper,we introduce how to synthesize and optimize space truss design through two *** study will help to improve design ***,it provides a theoretical basis for the automatic construction of space truss structures,especially in the next stage.

关键词： Adjacency matrix Finite screw On-orbit construction modeling Space applications Space trusses Topology design

Discrepant roles of adsorbed OH^* species on IrWOx for boosting alkaline hydrogen electrocatalysis

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Science Bulletin 2020年第20期65卷 1735-1742,M0004页

作者： Luhong Fu Fulin Yang youcheng hu Yunbo Li Shengli Chen Wei Luo hubei Electrochemical Power Sources Key Laboratory College of Chemistry and Molecular SciencesWuhan UniversityWuhan 430072China Suzhou Institute of Wuhan University Suzhou 215123China

Improving the slow kinetics of alkaline hydrogen electrode reactions, involving hydrogen oxidation and evolution reactions(HOR/HER) is highly desirable for accelerating the commercialization of alkaline exchange membrane-based fuel cells(AEMFCs) and water electrolyzers(AEMWEs). However, fundamental understanding of the mechanism for HOR/HER catalysis under alkaline media is still debatable. Here we develop an amorphous tungsten oxide clusters modified iridium-tungsten nanocrystallines(Ir WOx)which exhibited by far the highest exchange current density and mass activity, about three times higher than the commercial Pt/C toward alkaline HOR/HER. Density functional theory(DFT) calculations reveal the WOxclusters act as a pivotal role to boost reversible hydrogen electrode reactions in alkaline condition but via different mechanisms, which are, hydrogen binding energy(HBE) mechanism for HOR and bifunctional mechanism for HER. This work is expected to promote our fundamental understanding about the alkaline HOR/HER catalysis and provide a new avenue for rational design of highly efficient electrocatalysts toward HOR/HER under alkaline electrolytes.

关键词： Hydrogen oxidation reacion Hydrogen evolution reaction IrWOx HBE Bi-functional mechanism

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基于注意力机制的航拍图像目标检测算法

激光与光电子学进展 2023年第12期60卷 312-322页

作者：白宗宝张俊举高原胡友成南京理工大学电子工程与光电技术学院江苏南京210094 南京理工大学紫金学院电子工程与光电技术学院江苏南京210023

针对现有基于水平视角图像的目标检测网络在无人机航拍图像上误检率和漏检率高的问题,提出一种基于改进注意力机制的航拍图像目标检测算法。首先,在Faster R-CNN主干网络输出端引入一种三叉戟注意力机制,分别提取三路池化层和三路扩张... 详细信息

针对现有基于水平视角图像的目标检测网络在无人机航拍图像上误检率和漏检率高的问题,提出一种基于改进注意力机制的航拍图像目标检测算法。首先,在Faster R-CNN主干网络输出端引入一种三叉戟注意力机制,分别提取三路池化层和三路扩张卷积层的多模式信息及多尺度特征信息进行压缩,实现特征通道和空间像素区域的权重再分配。其次,针对航拍图像目标的分类和边界框回归,引入一种双头检测机制,充分利用目标的语义信息和空间位置信息。在相关数据集上对所提算法进行评测,并与其他目标检测算法进行对比。结果表明所提算法的平均精度均值得到显著提升,在不同场景下的无人机航拍图像目标检测中获得更好的效果。

关键词：机器视觉无人机目标检测注意力机制双头检测机制

R-matrix for the 8-Dimensional Spin Representation of Uq(so7)

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Acta Mathematica Sinica,English Series 2024年第2期40卷 485-497页

作者： Hong Mei hu Nai Hong hu School of Mathematical Sciences Suzhou University of Science and TechnologySuzhou 215009P.R.China School of Mathematical Sciences MOE Key Laboratory of Mathematics and Engineering Applications&Shanghai Key Laboratory of PMMPEast China Normal UniversityShanghai 200241P.R.China

The purpose of the paper is to describe the solution to the quantum Yang-Baxter equation associated with the 8-dimensional spin representation Tsp of Uq(so7).The self-duality of Tsp and the symmetry of the corresponding braiding matrix are ***,the minimal polynomial of the braiding R-matrix of Tsp is presented explicitly in an ingenious method by taking advantage of nice features of the spin representation Tsp.

关键词： Braiding R-matrix spin module minimal polynomial

Mapping out the reaction network of humin formation at the initial stage of fructose dehydration in water

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Green Energy & Environment 2024年第6期9卷 1016-1026页

作者： Xing Fu Yexin hu Ping hu hui Li Shuguang Xu Liangfang Zhu Changwei hu Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengduSichuan610064China State Key Laboratory of Southwestern Chinese Medicine Resources Innovative Institute of Chinese Medicine and PharmacyChengdu University of Traditional Chinese MedicineChengduSichuan611137China

The formation of humins hampers the large-scale production of 5-hydroxymethylfurfural(HMF)in ***,a detailed reaction network of humin formation at the initial stage of fructose-to-HMF dehydration in water is delineated by combined experimental,spectroscopic,and theoretical *** bimolecular reaction pathways to build up soluble humins are *** is,the intermolecular etherification of β-furanose at room temperature initiates the C12 path,whereas the C-C cleavage of a-furanose at 130-150℃ leads to C11 path,and that of open-chain fructose at 180℃ to C11' *** successive intramolecular dehydrations and condensations of the as-formed bimolecular intermediates lead to three types of soluble *** show that the C12 path could be restrained by using HCl or AlCl_(3) catalyst,and both the C12 and C110 paths could be effectively inhibited by adding THF as a co-solvent or accelerating heating rate via microwave heating.

关键词： Carbohydrates 5-hydroxymethylfurfural Reaction network Soluble humins Tautomer