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International Journal of Mining Science and Technology 2023年第6期33卷 761-772页

作者： Zhanguo Ma pengfei yan Shixing Cheng Peng Gong Fuzhou Qi Jianguo Wang State Key Laboratory for Geomechanics and Deep Underground Engineering China University of Mining and TechnologyXuzhou 221116China School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhou 221116China

Investigations on the dynamic mechanical properties and failure mechanisms of coal under in-situ stress is essential for the prevention of dynamic disasters in deep coal ***,a modified true triaxial Hopkinson bar was employed to explore the dynamic mechanical behaviors of coal at different confining pressures(0–20 MPa)and strain rates(40–220 s^(-1)).The results show that the dynamic peak stress is positively correlated with lateral static pre-stressσy andσz,but negatively correlated with axial static prestressσ*** approximate strain rates,increasing the lateral static pre-stress facilitates increasing the dynamic peak stress,but the minimum lateral static pre-stress is the primary factor limiting a significant increase in dynamic peak stress of ***,the dynamic differential stress is linearly related to the logarithm of strain rate,and the peak strain varies linearly with strain ***,there is no significant correlation between confining pressure and peak ***,X-ray CT images and photographic fracture observations of coal samples show the failure patterns under uniaxial and triaxial conditions are splitting failure and shear failure,*** device provides a viable approach for fully comprehending the dynamic mechanical behaviors of rock-like material in complex stress conditions.

关键词： Coal True triaxial SHPB test Dynamic mechanical properties Failure characteristics

CO_(2)-Induced Modulation of Si-O Bonds for Low Temperature Plastic Deformation of Amorphous Silica Nanoparticles with Enhanced Photoluminescence

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Energy & Environmental Materials 2024年第4期7卷 404-412页

作者： Kang Huang Wenzhuo Wu Song Xu pengfei yan Zhongming Wei Qun Xu Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450001China College of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of SciencesBeijing 100083China

Modulation of Si-O bonds under mild conditions has been a challenging issue in the field of material science,which is critical to manufacture highperformance silica-based optical and photonic ***,we introduce a nondestructive technique to achieve Si-O bond rearrangement,leading to plastic deformation and photoluminescence enhancement of amorphous silica nanoparticles using supercritical carbon dioxides in EtOH/H_(2)O solution under mild ***,plastic deformation is achieved by treating hollow mesoporous silica nanospheres using supercritical CO_(2)at 40°C under 20 *** and theoretical studies revealed the critical role of supercritical CO_(2)in the plastic deformation process,which can be intercalated into the hollow mesoporous silica nanospheres with anisotropic stresses and induces the rearrangement of Si-O bonds and transformation of ring *** work suggests a novel approach to engineer high-performance nano-silica glass components for numerous optical and photonic devices under mild condition.

关键词： amorphous silica anisotropic stress photoluminescence plastic deformation supercritical CO_(2)

Quadruple-stranded Eu-helicate Assembled from Bis-β-diketonate： Its Stability Towards Metal Ions

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Chemical Research in Chinese Universities 2016年第4期32卷 534-538页

作者： ZHANG Lei LI Hongfeng CHEN Peng SUN Wenbin yan pengfei Key Laboratory of Functional Inorganic Material Chemistry Ministry of Education School of Chemistry and Materials Science Heilong/iang University Harbin 150080 P. R. China

Herein, we reported the synthesis and investigation of highly luminescent quadruple-stranded helicate （C6H 16N）4[Eu2（MBDA）4]2·3 C4H10O.4C2H 3N（ 1-Eu） [H2M B DA=N-methyl-4,4＇-b i s（4,4,4-tri fl uoro-1,3-dioxob utyl）di- phenylamine] for its stability toward metal ions in the solution. The material was characterized via X-ray crystallo- graphic technique, Fourier transform infrared（FTIR） spectroscopy and electrospray ionization quadrapole time-of- flight（ESI-TOF） mass spectrometry. The results on the luminescence quantum yields clearly demonstrate that the ligand can effectively sensitize the luminescence of the Eu3＋ ions（φoverall=15%）. Upon the addition of different metal ions（i, e., Ag＋, Cd2＋, Zn2＋, Fe3＋, A13＋ and Ni2＋） to the CH3CN solution of compound I-Eu, the emission intensities of Eu3＋ ions at 612 nm were affected to some extent, which could be attributed to the presence of ion exchanges between Eu3＋ ions and the metals ions, and the result was confirmed by ESI-TOF mass spectrometry.

关键词： Helicate Fluorescence Displacement Bis-β-diketonate

Deciphering the critical effect of cathode-electrolyte interphase by revealing its dynamic evolution

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Journal of Energy Chemistry 2023年第6期81卷 192-199,I0006页

作者： Zhengfeng Zhang Changdong Qin Kuan Wang Xiao Han Jinhui Li Manling Sui pengfei yan Beijing Key Laboratory of Microstructure and Property of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China

Cathode electrolyte interphase(CEI)layer plays a crucial role in determining the electrochemical performance of lithium-ion *** by the sensitive nature of CEI and the lack of characterization techniques,its dynamic evolution during cycling,its formation mechanism,and its specific impact on battery performance are not yet fully ***,we systematically investigate the dynamic evolution of CEI layer and its critical effect on the cycling performance of LiCoO_(2)cathode by diverse characterization *** find that cycling voltage plays a key role in affecting CEI formation and evolution,and a critical potential(4.05 V ***)is identified,which acts as the switching potential between CEI deposition and *** show that CEI starts deposition in the discharge process when the potential is below 4.05 V,and CEI decomposition occurs when the potential is higher than 4.05 *** the battery is cycled below such a critical potential,a stable CEI layer is developed,which leads to superior cycling *** the battery is cycled above such a critical potential,a CEI-free cathode interface is observed,which also demonstrates good cycle ***,when the critical potential falls in the cycling voltage range,CEI deposition and decomposition are repeatedly switched on during cycling,leading to the dynamically unstable CEI *** unstable CEI layer causes continuous interfacial reaction and degradation,resulting in battery performance *** work deepens the understanding of the CEI formation and evolution mechanisms,and clarifies the critical effect of CEI layer on cycling performance,which provides new insights into stabilizing the electrode-electrolyte interface for high-performance rechargeable batteries.

关键词： LiCoO_(2) CEI Lithium-ion battery Electron microscopy XPS

Selective core-shell doping enabling high performance 4.6 V-LiCoO_(2)

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Journal of Energy Chemistry 2024年第8期95卷 684-693,I0015页

作者： Yueming Xia Jianrui Feng Jinhui Li yan Li Zhengfeng Zhang Xiaoqi Wang Jianli Shao Manling Sui pengfei yan Beijing Key Laboratory of Microstructure and Property of Solids College of Materials Science&EngineeringBeijing University of TechnologyBeijing 100124China PetroChina Research Institute of Petroleum Exploration&Development Beijing 100083China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

Constructing robust surface and bulk structure is the prerequisite for realizing high performance high voltage LiCoO_(2)(LCO).Herein,we manage to synthesize a surface Mg-doping and bulk Al-doping coreshell structured LCO,which demonstrates excellent cycling ***-cell shows 94.2%capacity retention after 100 cycles at 3.0-4.6 V(***/Li^(+))cycling,and no capacity decay after 300 cycles for fullcell test(3.0-4.55 V).Based on comprehensive microanalysis and theoretical calculations,the degradation mechanisms and doping effects are systematically *** the undoped LCO,high voltage cycling induces severe interfacial and bulk degradations,where cracks,stripe defects,fatigue H2 phase,and spinel phase are identified in grain *** the doped LCO,Mg-doped surface shell can suppress the interfacial degradations,which not only stabilizes the surface structure by forming a thin rock-salt layer but also significantly improves the electronic conductivity,thus enabling superior rate *** Al-doping can suppress the lattice"breathing"effect and the detrimental H3 to H1-3 phase transition,which minimizes the internal strain and defects growth,maintaining the layered structure after prolonged *** theoretical calculations,this work deepens our understanding of the doping effects of Mg and Al,which is valuable in guiding the future material design of high voltage LCO.

关键词： Lithium-ion battery Doping effect Failure mechanism High-voltage LiCoO_(2) Electron microscopy

Early-stage latent thermal failure of single-crystal Ni-rich layered cathode

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Journal of Energy Chemistry 2024年第9期96卷 578-587页

作者： Xiao Han Ruoyu Xu yan Li yang Ding Manchen Zhang Bo Wang Xiaoxing Ke Manling Sui pengfei yan Beijing Key Laboratory of Microstructure and Property of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Watt Laboratory Central Research InstituteHuawei Technologies Co.LTDShenzhen 518129GuangdongChina

High nickel content worsens the thermal stability of layered cathodes for lithium-ion batteries,raising safety concerns for their *** understanding the thermal failure process can offer valuable guidance for material optimization on thermal stability and new opportunities in monitoring battery thermal runaway(TR).Herein,this work comprehensively investigates the thermal failure process of a single-crystal nickel-rich layered cathode and finds that the latent thermal failure starts at∼120℃far below the TR temperature(225℃).During this stage of heat accumulation,sequential structure transition is revealed by atomic resolution electron microscopy,which follows the layered→cation mixing layered→LiMn_(2)O_(4)-type spinel→disordered spinel→rock *** progression occurs as a result of the continuous migration and densification of transition metal *** transition generates gaseous oxygen,initially confined within the isolated closed pores,thereby not showing any thermal failure phenomena at the *** temperature leads to pore growth and coalescence,and eventually to the formation of open pores,causing oxygen gas release and weight loss,which are the typical TR *** highlight that latent thermal instability occurs before the macro-level TR,suggesting that suppressing phase transitions caused by early thermal instability is a crucial direction for material *** findings can also be used for early warning of battery thermal runaway.

关键词： Thermal runaway Nickel-rich layered cathode Transmission electron microscopy Lithium-ion battery Phase transition

Synergistic tuning of electrochemical surface area and surface Co^(3+)by oxygen plasma enhances the capacities of Co_(3)O_(4)lithium-oxygen battery cathodes

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Chinese Chemical Letters 2021年第11期32卷 3491-3495页

作者： Xueli Guo Liang Xiao pengfei yan Ming Li Mingjun Zhu Jinping Liu School of Chemistry Chemical Engineering and Life ScienceWuhan University of TechnologyWuhan 430070China Key Laboratory for Photonic and Electronic Bandgap Materials Ministry of EducationSchool of Physics and Electronic EngineeringHarbin Normal UniversityHarbin 150025China Beijing Key Laboratory of Microstructure and Property of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China

Modifying electrochemical surface area(ECSA)and surface chemistry are promising approaches to enhance the capacities of oxygen cathodes for lithium-oxygen(Li-O_(2))*** various chemical approaches have been successfully used to tune the cathode surface,versatile physical techniques including plasma etching *** be more effortless and effective than arduous chemical ***,for the first time,we propose a facile oxygen plasma treatment to simultaneously etch and modify the surface of Co_(3)O_(4)nanosheet arrays(NAs)cathode for Li-O_(2)*** oxygen plasma not only etches Co_(3)O_(4)nanosheets to enhance the ECSA but also lowers the oxygen vacancy concentration to enable a Co^(3+)-rich *** addition,the NA architecture enables the full exposure of oxygen vacancies and surface Co^(3+)that function as the catalytically active ***,the synergistic effects of enhanced ECSA,modest oxygen vacancy and high surface Co^(3+)achieve a significantly enhanced reversible capacity of 3.45 mAh/cm^(2)for Co_(3)O_(4)*** work not only develops a promising high-capacity cathode for Li-O_(2)batteries,but also provides a facile physical method to simultaneously tune the nanostructure and surface chemistry of energy storage materials.

关键词： CO_(3)O_(4)nanosheet arrays Oxygen plasma Electrochemical surface area Oxygen vacancy Co^(3+)-rich surface

LiCoO_(2) Epitaxial Film Enabling Precise Analysis of Interfacial Degradations

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Chinese Physics Letters 2021年第6期38卷 88-94页

作者： Changdong Qin Le Wang pengfei yan Yingge Du Manling Sui Beijing Key Laboratory of Microstructure and Property of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China Physical and Computational Sciences Directorate Pacific Northwest National Laboratory RichlandWA 99354USA

Interfacial structure evolution and degradation are critical to the electrochemical performance of LiCoO_(2)(LCO),the most widely studied and used cathode material in lithium ion *** understand such processes requires precise and quantitative ***,we use well-defined epitaxial LCO thin films to reveal the interfacial degradation *** our systematical investigations,we find that surface corrosion is significant after forming the surface phase transition layer,and the cathode electrolyte interphase(CEI)has a double layer structure,an inorganic inner layer containing CoO,LiF,LiOH/Li_(2)O and Li_(x)PF_(y)O_(2),and an outmost layer containing Li2CO_(3) and organic carbonaceous ***,surface cracks are found to be pronounced due to mechanical failures and chemical *** work demonstrates a model material to realize the precise measurements of LCO interfacial degradations,which deepens our understanding on the interfacial degradation mechanisms.

关键词： corrosion interfacial precise

The interphasial degradation of 4.2 V-class poly(ethylene oxide)-based solid batteries beyond electrochemical voltage limit

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Journal of Energy Chemistry 2022年第12期75卷 504-511,I0013页

作者： Renzhi Huang yang Ding Fenglin Zhang Wei Jiang Canfu Zhang pengfei yan Min Ling Huilin Pan Zhejiang Provincial Key Laboratory of Advanced Chemical Engineering Manufacture Technology College of Chemical and Biological EngineeringZhejiang UniversityHangzhou 310027ZhejiangChina Department of Chemistry Zhejiang UniversityHangzhou 310027ZhejiangChina Beijing Key Laboratory of Microstructure and Properties of Solids Faculty of Materials and ManufacturingBeijing University of TechnologyBeijing 100124China State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou 310027ZhejiangChina

Solid-state polymer electrolytes(SPEs)have attracted increasing attention due to good interfacial contact,light weight,and easy ***,the practical application of SPEs such as the most widely studied poly(ethylene oxide)(PEO)in high-energy solid polymer batteries is still challenging,and the reasons are yet ***,it is found that the mismatch between PEO and 4.2 V-class cathodes is beyond the limited electrochemical window of PEO in the solid Li Ni_(1/3)Mn_(1/3)Co_(1/3)O_(2)(NMC)-PEO *** initial oxidation of PEO initiates remarkable surface reconstruction of NMC grains in solid batteries that are different from the situation in liquid ***-aligned nanovoids are observed in NMC grains during the diffusion of surface reconstruction layers towards the bulk in solid *** substantial interphasial degradation,therefore,blocks smooth Li+transport across the NMC-PEO interface and causes performance degradation.A thin yet effective Li F-containing protection layer on NMC can effectively stabilize the NMC-PEO interface with a greatly improved lifespan of NMC|PEO|Li *** work deepens the understanding of degradations in high-voltage solid-state polymer batteries.

关键词： Poly(ethylene oxide) Surface reconstruction Interphasial degradation High-energy solid polymer batteries

Study on creep deformation and energy development of underground surrounding rock under four‐dimensional support

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Deep Underground Science and Engineering 2024年第1期3卷 25-38页

作者： Zhanguo Ma Junyu Sun Peng Gong pengfei yan Nan Cui Ruichong Zhang School of Mechanics and Civil Engineering China University of Mining and TechnologyXuzhouChina State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering China University of Mining and TechnologyXuzhouChina Department of Mining Engineering Colorado School of MinesGoldenUSA

There is an urgent need to develop optimal solutions for deformation control of deep high‐stress roadways,one of the critical problems in underground *** previously proposed four‐dimensional support(hereinafter 4D support),as a new support technology,can set the roadway surrounding rock under three‐dimensional pressure in the new balanced structure,and prevent instability of surrounding rock in underground ***,the influence of roadway depth and creep deformation on the surrounding rock supported by 4D support is still *** study investigated the influence of roadway depth and creep deformation time on the instability of surrounding rock by analyzing the energy *** elastic strain energy was analyzed using the program redeveloped in *** numerical simulation results indicate that the combined support mode of 4D roof supports and conventional side supports is highly applicable to the stability control of surrounding rock with a roadway depth exceeding 520 *** the increase of roadway depth,4D support can effectively restrain the area and depth of plastic deformation in the surrounding ***,4D support limits the accumulation range and rate of elastic strain energy as the creep deformation time increases.4D support can effectively reduce the plastic deformation of roadway surrounding rock and maintain the stability for a long deformation period of 6 *** confirmed by in situ monitoring results,4D support is more effective for the long‐term stability control of surrounding rock than conventional support.

关键词： coal mines elastic strain energy four‐dimensional support large roadway depth long‐term stability control plastic deformation surrounding rock