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INTERACTION BETWEEN WAVES,STRUCTURES AND SAND BEDS

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Journal of Hydrodynamics 1995年第4期7卷 103-110页

作者： gao, xueping Zhao, Zidan Tianjin Univ Tianjin China

This dissertation includes two parts. In part one, the standing wave motions and scours of sand bed in front of breakwaters by waves were investigated systematically. The wave surfaces and velocity field with an arbitrary bottom boundary were calculated based on the MAC method (Marker and Cell method). The scours in front of breakwaters under the action of standing waves, breaking waves and broken waves were investigated systematically based on experiments and theoretical analysis. Meanwhile, the sediment threshold was studied. In part two, a new concept consolidation force for the properties of consolidated silt was suggested in order to study the threshold and transportation, then, the erosions around an artificial island built on consolidated silt sea bed under the action of combined waves and currents were investigated by the Physical Model based on the principle of the Series Model method.

关键词： Breakwaters Consolidation Flow interactions Numerical analysis Sand Sediment transport Water waves

Metal phosphides and borides as the catalytic host of sulfur cathode for lithium–sulfur batteries

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International Journal of Minerals,Metallurgy and Materials 2022年第5期29卷 990-1002页

作者： Rui gao Zhenyu Wang Sheng Liu Guangjie Shao xueping gao College of Environmental and Chemical Engineering Yanshan UniversityQinhuangdao 066004China School of Materials Science and Engineering Nankai UniversityTianjin 300350China

Lithium−sulfur batteries are one of the most competitive high-energy batteries due to their high theoretical energy density of _(2)600 W·h·kg^(−1).However,their commercialization is limited by poor cycle stability mainly due to the low intrinsic electrical conductivity of sulfur and its discharged products(Li_(2)S_(2)/Li_(2)S),the sluggish reaction kinetics of sulfur cathode,and the“shuttle effect”of soluble intermediate lithi-um polysulfides in ether-based *** address these challenges,catalytic hosts have recently been introduced in sulfur cathodes to en-hance the conversion of soluble polysulfides to the final solid products and thus prevent the dissolution and loss of active-sulfur *** this review,we summarize the recent progress on the use of metal phosphides and borides of different dimensions as the catalytic host of sulfur cathodes and demonstrate the catalytic conversion mechanism of sulfur cathodes with the help of metal phosphides and borides for high-en-ergy and long-life lithium-sulfur ***,future outlooks are proposed on developing advanced catalytic host materials to improve battery performance.

关键词： lithium–sulfur batteries sulfur cathode catalytic host metal phosphides metal borides

High-Entropy Spinel Oxide Nanofibers as Catalytic Sulfur Hosts Promise the High Gravimetric and Volumetric Capacities for Lithium–Sulfur Batteries

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Energy & Environmental Materials 2022年第2期5卷 645-654页

作者： Liyuan Tian Ze Zhang Sheng Liu Guoran Li xueping gao Institute of New Energy Material Chemistry School of Materials Science and EngineeringRenewable Energy Conversion and Storage CenterNankai UniversityTianjin 300350China

The exploration of new catalytic hosts is highly important to tackle the sluggish electrochemical kinetics of sulfur redox for achieving high energy density of lithium–sulfur ***,for the first time,we present high-entropy oxide(HEO,(Mg_(0.2)Mn_(0.2)Ni_(0.2)Co_(0.2)Zn_(0.2))Fe_(2)O_(4))nanofibers as catalytic host of *** HEO nanofibers show a synergistic effect among multiple metal cations in spinel structure that enables strong chemical confinement of soluble polysulfides and fast kinetics for polysulfide ***,the S/HEO composite displays the high gravimetric capacity of 1368.7 mAh g^(−1) at 0.1 C rate,excellent rate capability with the discharge capacity of 632.1 mAh g^(−1) at 5 C rate,and desirable cycle ***,the S/HEO composite shows desirable sulfur utilization and good cycle stability under a harsh operating condition of high sulfur loading(4.6 mg cm^(−2))or low electrolyte/sulfur ratio(5μL mg^(−1)).More impressively,the high volumetric capacity of 2627.9 mAh cm^(−3) is achieved simultaneously for the S/HEO composite due to the high tap density of 1.92 g cm^(−3),nearly 2.5 times of the conventional sulfur/carbon ***,based on high-entropy oxide materials,this work affords a fresh concept of elevating the gravimetric/volumetric capacities of sulfur cathodes for lithium–sulfur batteries.

关键词： catalytic host high-entropy oxide lithium-sulfur battery polysulfide conversion spinel oxide nanofibers

High-Entropy Alloys to Activate the Sulfur Cathode for Lithium-Sulfur Batteries

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Energy & Environmental Materials 2023年第3期6卷 40-49页

作者： Zhenyu Wang Hailun Ge Sheng Liu Guoran Li xueping gao Institute of New Energy Material Chemistry School of Materials Science and EngineeringRenewable Energy Conversion and Storage CenterNankai UniversityTianjin 300350China

Sulfur element possesses an ultrahigh theoretical specific capacity,while the utilization of sulfur in the whole cathode is lower obviously owing to the sluggish kinetics of sulfur and discharged products,limiting the enhancement on energy density of lithium-sulfur ***,for the first time,Fe_(0.24)Co_(0.26)Ni_(0.10)Cu_(0.15)Mn_(0.25)high-entropy alloy is introduced as the core catalytic host to activate the electrochemical performance of the sulfur cathode for lithium-sulfur *** is manifested that Fe_(0.24)Co_(0.26)Ni_(0.10)Cu_(0.15)Mn_(0.25)high-entropy alloy nanocrystallites distributed on nitrogen-doped carbon exhibit high electrocatalytic activity toward the conversion of solid sulfur to solid discharged products across soluble intermediate lithium *** particular,benefiting from the accelerated kinetics by high-entropy alloy nanocrystallites and synergistic adsorption by nitrogen-doped carbon,the cathode exhibits high reversible capacity of 1079.5 mAh g_(-cathode)^(-1)(high utilization of 89.4%)with the whole cathode as active material,instead of sulfur ***,under both lean electrolyte(3μmg^(-1))and ultrahigh sulfur loading(27.0 mg cm^(-2))condition,the high discharge capacity of 868.2 mAh g_(-cathode)^(-1)can be still achieved for the sulfur *** strategy opens up a new path to explore catalytic host materials for enhancing the utilization of sulfur in the whole cathode for lithium-sulfur batteries.

关键词： catalytic host electrochemical performance high-entropy alloy lithium–sulfur batteries sulfur cathode

Inverse-opal structured TiO_(2) regulating electrodeposition behavior to enable stable lithium metal electrodes

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Green Energy & Environment 2023年第6期8卷 1664-1672页

作者： Xuewen Wu Shaolun Cui Minfei Fei Sheng Liu xueping gao Guoran Li Institute of New Energy Material Chemistry School of Materials Science and EngineeringRenewable Energy Conversion and Storage CenterNankai UniversityTianjin300350China Department of Materials Science and Metallurgy University of CambridgeCambridge CB30FSUK

Lithium metal anode is almost the ultimate choice for high-energy density rechargeable batteries, but its uneven electrochemical dissolution-deposition characteristics lead to poor cycle stability and lithium dendrites safety problems. The fundamental solution to the problems is to interfere electrodeposition process of lithium metal so that it can be carried out reversibly and stably. In this work, an inverse-opal structured TiO2membrane with a thickness of only ~1 μm is designed to regulate the electrodeposition behavior of lithium metal, in which the ordered channels homogenize mass transfer process, the anatase TiO_(2)walls of the ion channels reduce desolvation barrier of solvated lithium-ions, and the spherical cavities with a diameter of ~300 nm confine migration of the adsorbed lithium atoms during electrocrystallization to diminish overpotential of lithium. These systematic effects cover and essentially change the whole process of electrodeposition of lithium metal and eliminate the possibility of lithium dendrite formation. The as-obtained lithium metal electrode delivers a Coulombic efficiency of 99.86% in the 100th cycle, and maintains a low deposition overpotential of 0.01 V for 800 h.

关键词： Lithium metal anode Inverse-opal structure TiO2 Electrodeposition Lithium-sulfur battery

Carbon nitride transparent counter electrode prepared by magnetron sputtering for a dye-sensitized solar cell

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Green Energy & Environment 2017年第3期2卷 302-309页

作者： Chaoyu Wu Guoran Li Xueqin Cao Bao Lei xueping gao Institute of New Energy Material Chemistry School of Materials Science and Engineering National Institure for Advanced Materials Nankai University Collaborative Innovation Center of Chemical Science and Engineering (Tianjin) Tianjin Key Laboratory of Metal and Molecule Based Material ChemistryNankai University

Carbon nitride(CN_x) films supported on fluorine-doped tin oxide(FTO) glass are prepared by radio frequency magnetron sputtering, in which the film thicknesses are 90-100 nm, and the element components in the CNX films are in the range of x = 0.15-0.25. The as-prepared CN_x is for the first time used as counter electrode for dye-sensitized solar cells(DSSCs), and show a preparation-temperature dependent electrochemical performance. X-ray photoelectron spectroscopy(XPS) demonstrates that there is a higher proportion of sp^2 C=C and sp^3 C-N hybridized bonds in CN_x-500(the sample treated at 500 ℃) than in CNX-RT(the sample without a heat treatment). It is proposed that the sp^2 C=C and sp^3 C-N hybridized bonds in the CN_x films are helpful for improving the electrocatalytic activities in DSSCs. Meanwhile, Raman spectra also prove that CN_x-500 has a relatively high graphitization level that means an increasing electrical conductivity. This further explains why the sample after the heat treatment has a higher electrochemical performance in DSSCs. In addition, the as-prepared CN_x counter electrodes have a good light transmittance in the visible light region. The results are meaningful for developing low-cost metal-free transparent counter electrodes for DSSCs.

关键词： Solar cells Counter electrodes Carbon nitride Electrocatalysis Magnetron sputtering

依托公共技术平台的“三位一体”实践教学模式研究

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实验科学与技术 2025年第1期23卷 29-33页

作者：张爱敏高学平王桂龙山东大学材料科学与工程学院济南250061

实践教学是培养多元化创新型人才的重要途径,“分析测试方法”是理、工、农、医等多学科学生必须掌握的一门实践课程,该课程开设过程中存在内容简单陈旧、脱离产业实际等问题。该文借助公共技术平台的自身优势,提出了“教学-科研-产业... 详细信息

实践教学是培养多元化创新型人才的重要途径,“分析测试方法”是理、工、农、医等多学科学生必须掌握的一门实践课程,该课程开设过程中存在内容简单陈旧、脱离产业实际等问题。该文借助公共技术平台的自身优势,提出了“教学-科研-产业化”三位一体实践教学模式和“两步法”教学过程。课程授课主体由专业老师转化为学校公共技术服务平台,使课程的“实践”特征更明显。课程改革方案为培养多元化、创新型人才提供了重要途径和方法。

关键词：实践教学公共技术平台三位一体综合实验

A Tri-Salt Composite Electrolyte with Temperature Switch Function for Intelligently Temperature-Controlled Lithium Batteries

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Energy & Environmental Materials 2024年第6期7卷 84-93页

作者： Ende Fu Huimin Wang Yating Zhang Zhenxue Xiao Xiu Zheng Shuai Hao xueping gao Institute of New Energy Material Chemistry School of Materials Science and EngineeringNankai UniversityTianjin300350 China

The intense research of lithium-ion batteries has been motivated by their successful applications in mobile devices and electronic *** emerging of intelligent control in kinds of devices brings new requirements for battery *** high-energy lithium batteries are expected to respond or react under different environmental *** this work,a tri-salt composite electrolyte is designed with a temperature switch function for intelligently temperature-controlled lithium ***,the halide Li_(3)YBr_(6)together with LiTFSI and LiNO_(3)works as active fillers in a low-melting-point polymer matrix(polyethyleneglycol dimethyl ether(PEGDME)and polyethylene oxide(PEO)),which is further filled into the pre-lithiated alumina fiber *** 60°C,the composite electrolyte exists in the liquid state and fully contacts with the working electrodes on the liquid–solid interface,effectively minimizing the interfacial resistance and leading to high discharge capacity in the *** electrolyte is changed into a solid state below 30°C so that the ionic conductivity is significantly reduced and the interface resistance is increased dramatically on the solid–solid ***,by simply adjusting the temperature,the cell can be turned“ON”or“OFF”*** novel function of the composite electrolyte has enlightening significance in developing intelligently temperature-controlled lithium batteries.

关键词： composite electrolyte halide electrolyte low melting point solid-state battery temperature switch function

An in Vitro Investigation of Acid Etching Treatment Prior to Post and Core Cementation and Teeth Fracture Resistance

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Journal of Wuhan University of Technology(Materials Science) 2019年第5期34卷 1233-1237页

作者： MA Xiaoni gao Xu XU Xin School of Stomatology Shandong UniversityJinan 250012China Handong Provincial Key Laboratory of Oral Tissue Regeneration Jinan 250012China School of Material Science and Engineering Shandong UniversityJinan 250012China Yantai Stomatological Hospital Yantai 264000China

In order to investigate how to enhance the teeth fracture resistance after the post and core treatment, an in vitro study was conducted to measure the fracture resistance of endodontically treated teeth restored with cast post and core with two kinds of surface treatment technology and acid etching preparation on the dentinal surface. Sixty-four recently extracted human single-rooted first premolars were endodontically treated and sectioned approximately 1.5 mm above the cementoenamel junction to remove the coronal portion. Each specimen received a cast post, core build-up and a metal alloy crown restoration. All teeth were randomly divided into the smooth surface post, core repair group, the sand blasting surface post, and core repair group, each group was divided into 10 s, 30 s, 60 s acid corrosion treatment group and control group. In acid test groups, an acid etching solution was applied for 10, 30 and 60 seconds, respectively, to the root canal wall surface. Each specimen was embedded in acrylic resin block and tested in an electronic universal testing machine. Fracture loads results showed that canal acid etching could increase teeth fracture resistance strength both in smooth groups and sandblasting group, and achieved the best effect when acid etching for 30 s. Sand spray treatment on the surface of the cast metal post can improve the flexural strength of the teeth after postcrown restoration. Acid etching on the root canal wall surfaces and sand spray treatment on the surface of the cast metal post can improve the flexural strength of the root after post-crown restoration. Therefore, these two methods could be used to strengthen the tooth fracture resistance, and maintain the long-term therapeutic effect of cast post and core restoration.

关键词： acid etching cast post and core resistance strength surface treatment