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Recent progress about transmission electron microscopy characterizations on lithium-ion batteries

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Journal of Energy Chemistry 2024年第8期95卷 39-56页

作者： Yihang Liu Qiuyun Li Ziqiang Wang institute of Materials research Shenzhen International Graduate School Tsinghua University

With the rapid development of portable electronics, new energy vehicles, and smart grids, ion batteries are becoming one of the most widely used energy storage devices, while the safety concern of ion batteries has always been an urgent problem to be solved. To develop a safety-guaranteed battery, the characterization of the internal structure is indispensable, where electron microscopy plays a crucial role. Based on this, this paper summarizes the application of transmission electron microscopy(TEM) in battery safety, further concludes and analyzes the aspects of dendrite growth and solid electrolyte interface(SEI) formation that affect the safety of ion batteries, and emphasizes the importance of electron microscopy in battery safety research and the potential of these techniques to promote the future development of this field. These advanced electron microscopy techniques and their prospects are also discussed.

关键词： Dendrites Electron microscopy characterizations Lithium-ion batteries SEI

Considerations of advanced aqueous batteries recycling:A perspective

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Journal of Energy Chemistry 2024年第6期93卷 46-54,I0002页

作者： Yun Zhao Yuqiong Kang Hao Du Feiyu Kang Baohua Li institute of Materials research Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055GuangdongChina

1.Introduction Battery technology,serving as a basis for a rechargeable society,has developed rapidly over a century[1].The progress can be roughly divided into three stages,with the initial two mainly focusing on aqueous battery systems.Prior to 1859,research primarily focused on the conceptualization of batteries and the development of primary(non-rechargeable)cells[2].In the subsequent150 years,rechargeable battery technology emerged。

关键词： battery Battery primarily

Large-disturbance Stability Analysis of Power Systems with Synchronous Generator and Converter-interfaced Generation

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Journal of Modern Power Systems and Clean Energy 2024年第3期12卷 997-1002页

作者： Lei Chen Yong Min Liangshuai Hao Guangzheng Xing Yalou Li Shiyun Xu IEEE Department of Electrical Engineering Tsinghua University China Electric Power research institute

This letter studies large-disturbance stability of the power system with a synchronous generator(SG) and a converter-interfaced generation(CIG) connected to infinite bus. The power system is multi-timescale and first simplified. It is shown that the boundary of region of attraction(ROA) of the simplified model is composed of stable manifolds of unstable equilibrium point(UEP) or semi-singular point(SSP), named anchor points, and singular surface pieces. The type of anchor point determines the dominant instability pattern of the power system. When the anchor point is UEP or SSP, the dominant instability pattern is the instability of rotor angle of SG or the instability of phase-locked loop and outer control loop(OCL) of CIG, respectively. Transition of dominant instability pattern can be analyzed with the relative position relationship between UEP and SSP. The effect of OCL is discussed. When the OCL is activated, the ROA becomes smaller and the system is more prone to instability of CIG. It is necessary to consider the OCL when studying the large-disturbance stability of the power system.

关键词： Power system stability Mathematical models Phase locked loops Stability criteria Transient analysis Power system dynamics Rotors

Call for knowledge systematization:An example from lithium ion batteries recycling

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Journal of Energy Chemistry 2024年第7期94卷 169-170页

作者： Yun Zhao Baohua Li institute of Materials research Tsinghua Shenzhen International Graduate SchoolTsinghua UniversityShenzhen 518055GuangdongChina

Scientific research is one of the primary ways to drive human civilization forward.Countless research institutions and researchers worldwide are dedicated to exploring the unknown,resulting in a flood of research findings[1].For instance,Web of Science alone collects over 10,000 academic papers on a daily basis.While each research field typically has around 10%of review articles,these mainly focus on a limited portion of the subject,failing to provide a comprehensive and real-time updated overview.As a result,researchers or students in a particular field may spend several months,or even longer,comprehending the state of research that has developed over just a few years.The lack of systematic background often leads to redundant or similar studies,which is highly detrimental to the progress of science and technology.

关键词： lithium typically spend

Multiple-dimensioned defect engineering for graphite felt electrode of vanadium redox flow battery

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Carbon Energy 2024年第2期6卷 143-153页

作者： Yingqiao Jiang Yinhui Wang Gang Cheng Yuehua Li Lei Dai Jing Zhu Wei Meng Jingyu Xi Ling Wang Zhangxing He School of Chemical Engineering North China University of Science and TechnologyTangshanChina tsinghua Shenzhen International Graduate School Institute of Materials ResearchTsinghua UniversityShenzhenChina

The scarcity of wettability,insufficient active sites,and low surface area of graphite felt(GF)have long been suppressing the performance of vanadium redox flow batteries(VRFBs).Herein,an ultra-homogeneous multipledimensioned defect,including nano-scale etching and atomic-scale N,O codoping,was used to modify GF by the molten salt system.NH_(4)Cl and KClO_(3) were added simultaneously to the system to obtain porous N/O co-doped electrode(GF/ON),where KClO_(3) was used to ultra-homogeneously etch,and O-functionalize electrode,and NH4Cl was used as N dopant,respectively.GF/ON presents better electrochemical catalysis for VO_(2)+/VO_(2)+ and V3+/V2+ reactions than only O-functionalized electrodes(GF/O)and GF.The enhanced electrochemical properties are attributed to an increase in active sites,surface area,and wettability,as well as the synergistic effect of N and O,which is also supported by the density functional theory calculations.Further,the cell using GF/ON shows higher discharge capacity,energy efficiency,and stability for cycling performance than the pristine cell at 140 mA cm^(−2) for 200 cycles.Moreover,the energy efficiency of the modified cell is increased by 9.7% from 55.2% for the pristine cell at 260 mA cm^(−2).Such an ultra-homogeneous etching with N and O co-doping through“boiling”molten salt medium provides an effective and practical application potential way to prepare superior electrodes for VRFB.

关键词： graphite felt molten salt N O co-doping ultra-homogeneous etching vanadium redox flow battery

Conductive edge-warping graphite mesas for robust structural superlubricity

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Science China Technological Sciences 2024年第7期67卷 2040-2049页

作者： FENG WeiJia LIU Ying MA Ming PENG DeLi NIE JinHui State Key Laboratory of Tribology in Advanced Equipment & Department of Mechanical Engineering Tsinghua University Center for Nano and Micro Mechanics Tsinghua University institute of Superlubricity Technology Research Institute of Tsinghua University in Shenzhen

Structural superlubricity(SSL) refers to a state of ultralow friction and zero wear when two solid surfaces slide against each other. Recent investigations have identified amorphous carbon at the edge of the graphite mesa as the primary source of friction in such SSL systems. Here, the tensile stress of metal thin film is exploited to engineer vertically conductive edge-warping graphite mesas(EWGM). Through this approach, robust SSL performance is realized, demonstrated by sliding an 8 μm side length square EWGM on an atomically smooth Au substrate for 10000 cycles at a constant voltage of 1 m V. In this SSL system,differential friction coefficients lower than 1.5 × 10-4are achieved, with static contact resistance between EWGM and Au substrate as low as 28 ? and sliding contact resistance as low as 32 ?. Moreover, the EWGM exhibits SSL behavior on polished Si wafer substrates. Furthermore, because of the no-edge contact with the substrate during sliding, friction is independent of the sliding speed of the EWGM. This study presents the first successful fabrication of conductive EWGM. Remarkably, in both EWGM-Au and EWGM-Si SSL systems, the measured frictions are more than one order of magnitude lower than those of ordinary self-retracting graphite mesas with no-edge warping, and no wear is observed during extended current-carrying sliding.Overall, these findings establish a solid groundwork for the future realization of macroscale conductive SSL systems.

关键词： structural superlubricity graphite mesa contact resistance tensile stress edge warping

Interface strengthening for thermal sprayed WC-10Co4Cr coating subjected to pulsed magnetic treatment

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Rare Metals 2024年第2期43卷 780-795页

作者： Cheng-Kai Qian Qu Liu Heng Wang Ke-Jian Li Zhi-Peng Cai Department of Mechanical Engineering Tsinghua UniversityBeijing100084China Tianjin research institute for Advanced Equipment Tsinghua UniversityTianjin300304China State Key Laboratory of Tribology in Advanced Equipment Tsinghua UniversityBeijing100084China

The reliability of the coated industry components demands ideal fatigue properties of the coating,and it is mainly determined by the performance of the interfaces.In this study,pulsed magnetic treatment(PMT)was applied to the thermal sprayed WC-10Co4Cr coating,and the fatigue lifetime of the coated bolt increased by 219.82%under an imitation of the operating mode condition.Scratch tests further proved that both the adhesion and cohesion strength were improved after PMT,and they benefit from the interface strengthening effects.The formation of coherent WC/Co interfaces was characterized by in-situ transmission electron microscopy(TEM),and the molecular dynamic simulations indicate that the work of separation of these interfaces is much higher than the original disordered ones.Residual stress was relaxed and distributed more homogeneously after PMT,and it mainly contributes to the coating/substrate strengthening.This work provides a new post-treatment method focusing on the interfaces in the WC-based coating and gives insight into its mechanism so that it is hopeful to be applied to other kinds of coatings.

关键词： Cemented carbide coating Pulsed magnetic treatment Interface strengthening Fatigue properties Adhesion strength

Photonic neuromorphic architecture for tens-of-task lifelong learning

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Light(Science & Applications) 2024年第3期13卷 519-530页

作者： Yuan Cheng Jianing Zhang Tiankuang Zhou Yuyan Wang Zhihao Xu Xiaoyun Yuan Lu Fang Sigma Laboratory Department of Electronic EngineeringTsinghua UniversityBeijing 100084China Beijing National research Center for Information Science and Technology(BNRist) Beijing 100084China institute for Brain and Cognitive Science Tsinghua University(THUIBCS)Beijing 100084China

Scalable,high-capacity,and low-power computing architecture is the primary assurance for increasingly manifold and large-scale machine learning tasks.Traditional electronic artificial agents by conventional power-hungry processors have faced the issues of energy and scaling walls,hindering them from the sustainable performance improvement and iterative multi-task learning.Referring to another modality of light,photonic computing has been progressively applied in high-efficient neuromorphic systems.Here,we innovate a reconfigurable lifelong-learning optical neural network(L2 ONN),for highly-integrated tens-of-task machine intelligence with elaborated algorithm-hardware codesign.Benefiting from the inherent sparsity and parallelism in massive photonic connections,L2 ONN learns each single task by adaptively activating sparse photonic neuron connections in the coherent light field,while incrementally acquiring expertise on various tasks by gradually enlarging the activation.The multi-task optical features are parallelly processed by multi-spectrum representations allocated with different wavelengths.Extensive evaluations on freespace and on-chip architectures confirm that for the first time,L2 ONN avoided the catastrophic forgetting issue of photonic computing,owning versatile skills on challenging tens-of-tasks(vision classification,voice recognition,medical diagnosis,etc.)with a single model.Particularly,L2 ONN achieves more than an order of magnitude higher efficiency than the representative electronic artificial neural networks,and 14×larger capacity than existing optical neural networks while maintaining competitive performance on each individual task.The proposed photonic neuromorphic architecture points out a new form of lifelong learning scheme,permitting terminal/edge AI systems with light-speed efficiency and unprecedented scalability.

关键词： life neural versatile

Functional Optical Fiber Sensors Detecting Imperceptible Physical/Chemical Changes for Smart Batteries

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Nano-Micro Letters 2024年第8期16卷 268-308页

作者： Yiding Li Li Wang Youzhi Song Wenwei Wang Cheng Lin Xiangming He institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing 100084People’s Republic of China National Engineering research Center of Electric Vehicles Beijing Institute of Technology(BIT)Beijing 100081People’s Republic of China Shenzhen Automotive research institute of BIT(Shenzhen research institute of National Engineering research Center of Electric Vehicles) Shenzhen 518118People’s Republic of China

The battery technology progress has been a contradictory process in which performance improvement and hidden risks coexist.Now the battery is still a“black box”,thus requiring a deep understanding of its internal state.The battery should“sense its internal physical/chemical conditions”,which puts strict requirements on embedded sensing parts.This paper summarizes the application of advanced optical fiber sensors in lithium-ion batteries and energy storage technologies that may be mass deployed,focuses on the insights of advanced optical fiber sensors into the processes of one-dimensional nano-micro-level battery material structural phase transition,electrolyte degradation,electrode-electrolyte interface dynamics to three-dimensional macro-safety evolution.The paper contributes to understanding how to use optical fiber sensors to achieve“real”and“embedded”monitoring.Through the inherent advantages of the advanced optical fiber sensor,it helps clarify the battery internal state and reaction mechanism,aiding in the establishment of more detailed models.These advancements can promote the development of smart batteries,with significant importance lying in essentially promoting the improvement of system consistency.Furthermore,with the help of smart batteries in the future,the importance of consistency can be weakened or even eliminated.The application of advanced optical fiber sensors helps comprehensively improve the battery quality,reliability,and life.

关键词： Smart battery Advanced embedded optical fiber sensor Battery internal physical/chemical state Quality-reliability-life characteristic