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Aligned Ion Conduction Pathway of Polyrotaxane‑Based Electrolyte with Dispersed Hydrophobic Chains for Solid‑State Lithium–Oxygen Batteries

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Nano-Micro Letters 2025年第2期17卷 169-186页

作者： Bitgaram kim Myeong‑Chang Sung Gwang‑Hee Lee Byoungjoon Hwang Sojung Seo ji‑Hun Seo Dong‑Wan kim Department of Materials Science and Engineering Korea University145 Anam‑RoSeongbuk‑GuSeoul 02841Republic of Korea School of Civil Environmental and Architectural EngineeringKorea University145 Anam‑RoSeongbuk‑GuSeoul 02841Republic of Korea Materials Science and Chemical Engineering Center Institute for Advanced Engineering(IAE)Yongin 17180Republic of Korea

A critical challenge hindering the practical application of lithium–oxygen batteries(LOBs)is the inevitable problems associated with liquid electrolytes,such as evaporation and safety *** study addresses these problems by proposing a modified polyrotaxane(mPR)-based solid polymer electrolyte(SPE)design that simultaneously mitigates solvent-related problems and improves ***-SPE exhibits high ion conductivity(2.8×10^(−3)S cm^(−1)at 25℃)through aligned ion conduction pathways and provides electrode protection ability through hydrophobic chain *** this mPR-SPE into solid-state LOBs resulted in stable potentials over 300 *** situ Raman spectroscopy reveals the presence of an LiO_(2)intermediate alongside Li_(2)O_(2)during oxygen *** situ X-ray diffraction confirm the ability of the SPE to hinder the permeation of oxygen and moisture,as demonstrated by the air permeability *** present study suggests that maintaining a low residual solvent while achieving high ionic conductivity is crucial for restricting the sub-reactions of solid-state LOBs.

关键词： Solid polymer electrolyte Lithium-oxygen batteries Polyrotaxane ion conductivity Hydrophobic chain

Postmortem ^(7)Li NMR analysis for assessing the reversibility of lithium metal electrodes in lithium metal batteries

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Journal of Energy Chemistry 2024年第7期94卷 430-440页

作者： Jaewon Baek Sunha kim Hee-tak kim Oc Hee Han Department of Chemical&Biomolecular Engineering KAISTDaejeon 34141Republic of Korea Metropolitan Seoul Center Korea Basic Science InstituteSeoul 03759Republic of Korea Graduate School of Analytical Science&Technology Chungnam National UniversityDaejeon 34134Republic of Korea

Despite the proficiency of lithium(Li)-7 NMR spectroscopy in delineating the physical and chemical states of Li metal electrodes,challenges in specimen preparation and interpretation impede its *** this study,we conducted a comprehensive postmortem analysis utilizing ^(7)Li NMR,employing a stan-dard magic angle spinning probe to examine protective-layer coated Li metal electrodes and LiAg alloy electrodes against bare Li metal electrodes within Li metal batteries(LMBs).Our investigation explores the effects of sample burrs,alignment with the magnetic field,the existence of liquid electrolytes,and precycling on the ^(7)Li NMR *** contrasting NMR spectra before and after cycling,we identi-fied alterations in Li^(0) and Li^(+) signals attributable to the degradation of the Li metal *** NMR analyses decisively demonstrate the efficacy of the protective layer in mitigating dendrite and solid elec-trolyte interphase ***,we noted that Li*ions near the Li metal surface exhibit magnetic susceptibility anisotropy,revealing a novel approach to studying diamagnetic species on Li metal elec-trodes in *** study provides valuable insights and practical guidelines for characterizing distinct lithium states within LMBs.

关键词： NMR spectroscopy Lithium-7 Lithium metal battery Electrolyte Electrode-protective layer Solid electrolyte interface Magnetic susceptibility anisotropy Lithium-metal NMR signal Diamagnetic^(7)Li NMR signal

Trend of Developing Aqueous Liquid and Gel Electrolytes for Sustainable,Safe,and High‑Performance Li‑Ion Batteries

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Nano-Micro Letters 2024年第1期16卷 17-34页

作者： Donghwan ji Jaeyun kim School of Chemical Engineering Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Department of Health Sciences and Technology Samsung Advanced Institute for Health Sciences&Technology(SAIHST)Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Biomedical Institute for Convergence at SKKU(BICS) Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Institute of Quantum Biophysics(IQB) Sungkyunkwan University(SKKU)Suwon 16419Republic of Korea Present Address:Department of NanoEngineering University of California San DiegoLa JollaSan DiegoCA 92093USA

Current lithium-ion batteries(LIBs)rely on organic liquid electrolytes that pose significant risks due to their flammability and *** potential for environmental pollution and explosions resulting from battery damage or fracture is a critical ***-based(aqueous)electrolytes have been receiving attention as an alternative to organic ***,a narrow electrochemicalstability window,water decomposition,and the consequent low battery operating voltage and energy density hinder the practical use of aqueous ***,developing novel aqueous electrolytes for sustainable,safe,high-performance LIBs remains *** Review first commences by summarizing the roles and requirements of electrolytes–separators and then delineates the progression of aqueous electrolytes for LIBs,encompassing aqueous liquid and gel electrolyte development trends along with detailed principles of the *** aqueous electrolytes are progressed based on strategies using superconcentrated salts,concentrated diluents,polymer additives,polymer networks,and artificial passivation layers,which are used for suppressing water decomposition and widening the electrochemical stability window of water of the *** addition,this Review discusses potential strategies for the implementation of aqueous Li-metal batteries with improved electrolyte–electrode interfaces.A comprehensive understanding of each strategy in the aqueous system will assist in the design of an aqueous electrolyte and the development of sustainable and safe high-performance batteries.

关键词： Lithium-ion battery(LIB) Aqueous electrolyte Gel electrolyte Electrochemical stability window Li dendrite

Improving toughness of medium-Mn steels after friction stir welding through grain morphology tuning

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Journal of Materials Science & Technology 2022年第23期118卷 243-254页

作者： Mun Sik Jeong tak Min Park Dong-Il kim Hidetoshi Fujii Hye ji Im Pyuck-Pa Choi Seung-Joon Lee Jeongho Han Division of Materials Science and Engineering Hanyang UniversitySeoul 04763Republic of Korea Department of Advanced Materials Engineering Korea Polytechnic UniversitySiheung 15073Republic of Korea Joining and Welding Research Institute Osaka UniversityOsaka 567-0047Japan Department of Materials Science and Engineering Korea Advanced Institute of Science and TechnologyDaejeon 34141Republic of Korea Department of Materials Science and Engineering Northwestern UniversityEvanstonIL 60208USA

This work demonstrated the viability of friction stir welding for the welding of medium-Mn steels when used as cryogenic vessel materials for liquefied gas *** used an intercritically annealed Fe-7 Mn-0.2 C-3 Al(wt.%)steel with a dual-phase(α'martensite andγ_(R) retained austenite)nanolaminate structure as a base material and systematically compared its microstructure and impact toughness after friction stir and tungsten inert gas *** friction stir welded specimen exhibited a large amount ofγ_(R) phase owing to a relatively low temperature during welding,whereas the tungsten inert gas welded specimen comprised only theα'***,the friction stir welded steel exhibited a tuned morphology of nanoscale globular microstructure at the weld zone and did not exhibit any prior austenite grain boundary due to active recrystallization caused by deformation during *** preserved fraction ofγ_(R) and morphological tuning in the weldment improved the impact toughness of the friction stir welded steel at low *** the steel processed by tungsten inert gas welding,the notch crack propagated rapidly along the prior austenite grain boundaries-weakened by Mn and P segregations-resulting in poor impact ***,the friction stir welded steel exhibited a higher resistance against notch crack propagation due to the slow crack propagation along the ultrafine ferrite/ferrite(α/α)interfaces,damage tolerance by the active transformation-induced plasticity from the large amount ofγR,and enhanced boundary cohesion by suppressed Mn and P segregations.

关键词： Charpy impact test Transformation-induced plasticity Friction stir welding Phase stability Medium-Mn steel

Optimization of rotor shape for constant torque improvement and radial magnetic force minimization

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Journal of Central South University 2012年第2期19卷 357-364页

作者： CHO Gyu-won WOO Seok-hyun ji Seung-hun PARK Kyoung-won JANG Ki-bong kim Gyu-tak School of Mechatronics Changwon National University

The design of notch and barrier was optimized in order to improve the characteristics of constant torque while minimizing the cogging torque that occurs as a result of teeth and slot structure. The barrier was installed in order to minimize the cogging torque and torque ripple by finite element method (FEM) with a reduced barrier width toward the center of magnetic pole. The position and width of notch, which can offset cogging torque, can be calculated with energy distribution of air-gap using Fourier series. The optimized model demonstrates a 60% decrease in the cogging torque, a 75.3% decrease in the torque ripple and a 3% increase in the operating torque when compared with the basic model.

关键词： permanent magnet synchronous motor barrier notch radial magnetic force cogging torque

Calculation of optimal current density of double side permanent magnet linear synchronous motor

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Journal of Central South University 2011年第1期18卷 165-170页

作者： JANG Ki-Bong AN Ho-jin kim Gyu-tak School of Mechatronics Changwon National University

The use of design method considering a coil temperature to maximize the thrust density of a double side coreless permanent magnet linear synchronous motor(PMLSM) was *** optimal current density where the coil temperature reaches an allowable temperature with heat analysis was applied to a magnetic circuit *** optimal current density is verified whenever the design parameters of the motor are *** design parameters of the motor were applied to thrust *** this way,the optimal model,which is a reversal of the existing design method,is *** results were compared with the experimental data to verify their *** the convection heat transfer coefficient is applied to other models,the results of the analysis and test values show good *** method proposed has some limitations.

关键词： permanent magnet linear synchronous motor current density heat transfer temperature thickness of coil

Advancement in materials for energy-saving lighting devices

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Frontiers of Chemical Science and Engineering 2012年第1期6卷 13-26页

作者： tak H.kim Wentai WANG Qin LI Department of Chemical Engineering Curtin UniversityPerth 6845Australia

This review provides a comprehensive account of energy efficient lighting devices, their working principles and the advancement of these materials as an underpinning to the development of technology. Particular attention has been given to solid state lighting devices and their applications since they have attracted the most interest and are the most promising. Solid state lighting devices including white light emitting diodes （LEDs）, organic LEDs （OLEDs）, quantum-dot LEDs （QLEDs） and carbon-dot LEDs （CLEDs） are promising energy efficient lighting sources for displays and general lighting. However there is no universal solution that will give better performance and efficiency for all types of applications. LEDs are replacing traditional lamp,; for both general lighting and display applications, whereas OLEDs are finding their own special application,; in various areas. QLEDs and CLEDs have advantages such as high quantum yields, narrow emission spectra, tunable emission spectra and good stability over OLEDs, so applications for these devices are being extended to new types of lighting sources. There is a great dean of research on these materials and their processing technologies and the commercial viability of these technologies appears strong.

关键词： energy-saving lighting devices solid statelighting devices

Optimal design of auxiliary-teeth to solve circulation current reduction of permanent magnet linear synchronous motor

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Journal of Central South University 2011年第3期18卷 690-696页

作者： JANG Ki-bong kim Jee-hyun AN Ho-jin kim Gyu-tak School of Mechatronics Changwon National University

A discontinuity of magnetic circuits according to the end effect is generated in the permanent magnet linear synchronous motor （PMLSM）. Due to the unbalanced back electro-motive force （EMF） and impedance produced, unbalanced current is generated. The cireulatin8 current, which is caused by a decrease in the thrust, is generated by the unbalanced current. The optimal design of auxiliary-teeth at the end of the mover was carried out to solve the unbalance of phase by using design of experiment （DOE）, and compared with the basic model through finite element analysis （FEA）. As a result, the auxiliary-teeth model compensates for the decrease of thrust caused by the unbalanced phase. Also, this model is proven to reduce the detent force by the vibration and noise of the PMLSM and copper loss caused by the circulating current.

关键词： permanent magnet linear synchronous motor auxiliary-teeth circulation current end effect thrust reduction

Developmental process of the arcuate fasciculus from infancy to adolescence: a diffusion tensor imaging study

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Neural Regeneration Research 2016年第6期11卷 937-943页

作者： Hyeong Jun tak jin Hyun kim Su Min Son Department of Physical Medicine and Rehabilitation School of Medicine Yeungnam University

We investigated the radiologic developmental process of the arcuate fasciculus（AF） using subcomponent diffusion tensor imaging（DTI） analysis in typically developing volunteers. DTI data were acquired from 96 consecutive typically developing children, aged 0–14 years. AF subcomponents, including the posterior, anterior, and direct AF tracts were analyzed. Success rates of analysis（AR） and fractional anisotropy（FA） values of each subcomponent tract were measured and compared. AR of all subcomponent tracts, except the posterior, showed a significant increase with aging（P 〈 0.05）. Subcomponent tracts had a specific developmental sequence： First, the posterior AF tract, second, the anterior AF tract, and last, the direct AF tract in identical hemispheres. FA values of all subcomponent tracts, except right direct AF tract, showed correlation with subject＇s age（P 〈 0.05）. Increased AR and FA values were observed in female subjects in young age（0–2 years） group compared with males（P 〈 0.05）. The direct AF tract showed leftward hemispheric asymmetry and this tendency showed greater consolidation in older age（3–14 years） groups（P 〈 0.05）. These findings demonstrated the radiologic developmental patterns of the AF from infancy to adolescence using subcomponent DTI analysis. The AF showed a specific developmental sequence, sex difference in younger age, and hemispheric asymmetry in older age.

关键词： tracts tensor younger older developmental maturation typically asymmetry anisotropy fractional