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Effects of conductive agent type on lithium extraction from salt lake brine with LiFePO_(4) electrodes

International Journal of Minerals,Metallurgy and Materials 2024年第4期31卷 678-687页

作者： Zhen Zhang Pan Luo Yan Zhang Yuhan Wang Li Liao Bo Yu Mingshan Wang Junchen Chen Bingshu Guo Xing Li School of New Energy and Materials Southwest Petroleum UniversityChengdu 610500China Energy Storage Research Institute Southwest Petroleum UniversityChengdu 610500China

Electrochemical lithium extraction from salt lakes is an effective strategy for obtaining lithium at a low cost.Nevertheless,the elevated Mg:Li ratio and the presence of numerous coexisting ions in salt lake brines give rise to challenges,such as prolonged lithium extraction periods,diminished lithium extraction efficiency,and considerable environmental pollution.In this work,Li FePO4(LFP)served as the electrode material for electrochemical lithium extraction.The conductive network in the LFP electrode was optimized by adjusting the type of conductive agent.This approach resulted in high lithium extraction efficiency and extended cycle life.When the single conductive agent of acetylene black(AB)or multiwalled carbon nanotubes(MWCNTs)was replaced with the mixed conductive agent of AB/MWCNTs,the average diffusion coefficient of Li+in the electrode increased from 2.35×10^(-9)or 1.77×10^(-9)to 4.21×10^(-9)cm^(2)·s^(-1).At the current density of 20 mA·g^(-1),the average lithium extraction capacity per gram of LFP electrode increased from 30.36 mg with the single conductive agent(AB)to 35.62 mg with the mixed conductive agent(AB/MWCNTs).When the mixed conductive agent was used,the capacity retention of the electrode after 30 cycles reached 82.9%,which was considerably higher than the capacity retention of 65.8%obtained when the single AB was utilized.Meanwhile,the electrode with mixed conductive agent of AB/MWCNTs provided good cycling performance.When the conductive agent content decreased or the loading capacity increased,the electrode containing the mixed conductive agent continued to show excellent electrochemical performance.Furthermore,a self-designed,highly efficient,continuous lithium extraction device was constructed.The electrode utilizing the AB/MWCNT mixed conductive agent maintained excellent adsorption capacity and cycling performance in this device.This work provides a new perspective for the electrochemical extraction of lithium using LFP electrodes.

关键词： salt lake brine lithium extraction electrochemical lithium extraction conductive agent extraction efficiency adsorption capacity

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Light extraction efficiency enhancement of GaN-based light emitting diodes by a ZnO current spreading layer

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Journal of Semiconductors 2009年第9期30卷 29-32页

作者：杨华王晓峰阮军李志聪伊晓燕段垚曾一平王国宏 R&D Center for Semiconductor Lighting Institute of SemiconductorsChinese Academy of Sciences

Gallium nitride （GaN） based light emitting diodes （LEDs） with a thick and high quality ZnO film as a current spreading layer grown by metal-source vapor phase epitaxy （MVPE） are fabricated successfully. Compared with GaN-based LEDs employing a Ni/Au or an indium tin oxide transparent current spreading layer, these LEDs show an enhancement of the external quantum efficiency of 93% and 35% at a forward current of 20 mA, respectively. The full width at half maximum of the ZnO （002） ω-scan rocking curve is 93 arcsec, which corresponds to a high crystal quality of the ZnO film. Optical microscopy and atomic force microscopy are used to observe the surface morphology of the ZnO film, and many regular hexagonal features are found. A spectrophotometer is used to study the different absorption properties between the ZnO film and the indium tin oxide film of the GaN LED. The mechanisms of the extraction quantum efficiency increase and the series resistance change of the GaN-based LEDs with ZnO transparent current spreading layers are analyzed.

关键词： GaN LED ZnO extraction efficiency transparent electrode

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Tuning a nano-pillar array for enhancing the photoluminescence extraction efficiency of GaN-based light-emitting diodes

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Chinese Physics B 2013年第4期22卷 519-522页

作者：陈夏梁柱洪陈湛旭杨伟明陈土福金崇君张佰君 State Key Laboratory of Optoelectronic Materials and Technologies School of Physics and Engineering Sun Yat-Sen University

We demonstrate the fabrication of hexagonal nano-pillar arrays at the surface of GaN-based light-emitting diodes （LEDs） by nanosphere lithography. By varying the oxygen plasma etching time, we could tune the size and shape of the pillar. The nano-pillar has a truncated cone shape. The nano-pillar array serves as a gradual effective refractive index matcher, which reduces the reflection and increases light cone. It is found that the patterned surface absorbs more pumping light. To compare extraction efficiencies of LEDs, it is necessary to normalize the photoluminescence power spectrum with total absorption rate under fixed pumping power, then we could obtain the correct enhancement factor of the photoluminescence extraction efficiency and optimized structure. The highest enhancement factor of the extraction efficiency is 10.6.

关键词： colloidal lithography light-emitting diode extraction efficiency

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Study of the influence of photon recycling on extraction efficiency in a slab Light Emitting Diode

Study of the influence of photon recycling on extraction eff...

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2007亚洲光电子会议固态照明与太阳能技术分会场

作者： YiChen Shuai GuangHan Fan TianMing Zhou ShuWen Zheng Institute of Optoelectronic material and devices South China Normal University GuangZhou P.R. China

Photon recycling effect has significant influence on the extraction efficiency of LEDs, which active regions possess high spontaneous emission efficiency, i.e. high material quality. Therefore, the conventional definition of internal quantum efficiency should be revised as pointed out by other researchers. In this work, some more detailed considerations of photon extraction efficiency in LEDs are examined using a simple slab structure. Theoretical modeling results show that in order to improve the overall light conversion efficiency, it is necessary to remove the device substrate, to optimize the overall doping profile design, and to use highly reflective metal contacts or DBR structures.

关键词： Photon recycling extraction efficiency Light Emitting Diode.

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Improvement of extraction efficiency for GaN-based light emitting diodes

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中国科学:技术科学 2010年第2期 205-205页

作者： SU YanKuin HUANG ChunYuan CHEN JianJhong KAO ChienChih TSAI ChunFu Department of Electrical Engineering “National” Cheng-Kung University Department of Electrical Engineering Kun Shan University of Technology Institute of Microelectronics “National” Cheng-Kung University Advanced Optoelectronic Technology Center “National” Cheng Kung University

A simple, low cost method for mass production to enhance the light extraction efficiency of GaN-related LEDs was proposed. With appropriate process parameters, the nature lithography of nanosphere can be used to fabricate two- dimensional nanostructures, including the nanomesh ZnO layer, photonic crystal (PhC) patterned p-GaN, and patterned sapphire substrates. Based on preliminary results, the extraction efficiencies of LEDs with these nanostructures can thus be improved and the nature lithography is demonstrated to be a promising method to be widely exploited in the manufacture of all kinds of LED devices.

关键词： extraction efficiency light emitting diodes patterned sapphire substrate

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Optimization of enrichment and pretreatment of low-activity radium isotopes in the open ocean

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海洋学报:英文版 2023年第8期42卷 171-177页

作者： Guiyuan Dai Guizhi Wang Qing Li Weizhen Jiang Fei Zhang State Key Laboratory of Marine Environmental Science Xiamen UniversityXiamen 361102China Fujian Provincial Key Laboratory for Coastal Ecology and Environmental Studies Xiamen UniversityXiamen 361102China College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China

In the open ocean,radium isotopes are useful tracers of residence time and water-mass mixing.However,limited by the measurement resolution of commonly used gamma counters,the low activity of radium in the open ocean makes it necessary to enrich radium from large volumes of seawater and pretreat radium-enriched carriers prior to measurements.The commonly applied method of radium enrichment and pretreatment,however,has limitations of uneven coating of MnO_(2)on cartridges,relatively expensive cartridges,time-consuming issues during cartridge-ashing,ash loss during transfer,and changes of gamma counters efficiency caused by different ash weights.To address these issues,in this study we optimized the enrichment and pretreatment of low-activity radium prior to measurements.Firstly,we replaced commonly used acrylic cartridges with cheaper polypropylene cartridges,which took 6 h to be ashed,42 h shorter than for acrylic cartridges.Secondly,MnO_(2)-coated cartridges were prepared with a circulating hot acidic KMnO_(4)solution to ensure homogeneous coating.The radium extraction efficiency of this MnO_(2)-coated cartridge was 20%-61%higher than that prepared by directly immersing cartridges in the solution.The radium delayed coincidence counter efficiency for MnO_(2)-coated cartridge was stable with a moisture content of 0.05-1.Lastly,after ashing cartridges,instead of directly transferring the ash to a measurement vial,a mixture of hydroxylamine hydrochloride and hydrochloric acid was used to completely leach the ash for long-lived radium,followed by coprecipitation by BaSO_(4),to avoid potential loss of ash during transfer and variations in measurement geometry due to different ash weights.And the recovery of long-lived radium pretreatment was 94%-102%,which improved by 11%compared with the common method.In addition,the radium extraction efficiency of the MnO_(2)-coated cartridge varied from 3%to 4%within the in situ pump working flow rate of 4-7 L/min,which fell within the measurement errors.

关键词： radium isotopes MnO_(2)-coated cartridge enrichment of Ra pretreatment of MnO_(2)-coated cartridges RaDeCC efficiency extraction efficiency

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Gas-liquid-liquid extraction in a novel rotating microchannel extractor

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Chinese Journal of Chemical Engineering 2020年第10期28卷 2523-2532页

作者： Rui Ma Chunxin Fan Yubin Wang Jianhong Luo Jun Li Sridhar Komarneni Department of Chemical Engineering Sichuan UniversityChengdu 610065China Department of Ecosystem Science and Management and Materials Research Institute 204 Energy and the Environment LaboratoryThe Pennsylvania State UniversityUniversity ParkPA 16802USA

In this work,a novel rotating microchannel extractor(RME)is designed and further used for the extraction of chromium(Ⅲ)from water.Unexpectedly,the micro-extraction had the same effect as carrying out 2.9-stage cross-flow extractions.Various factors,including the gas intake methods,gas intake quantity(Qg),distance between inner rotor and outer wall(D),rotational inner rotor speed(R)and volumetric flow rate(Qa,Qo),were selected to investigate their effect on the extraction efficiency(η)thoroughly.The relation map ofηwith Weaand We(o-g)for RME provides a comprehension for the gas–liquid–liquid extraction process in this RME system.

关键词： Microextraction Gas–liquid–liquid Rotating microchannel extractor Mass transfer extraction efficiency

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Mass transfer coefficient in the eductor liquid-liquid extraction column

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Chinese Journal of Chemical Engineering 2021年第12期34卷 27-35页

作者： Bahare Esmaeeli Ahad Ghaemi Mansour Shirvani Mostafa Hosseinzadeh School of Chemical Petroleum and Gas EngineeringIran University of Science&TechnologyNarmakTehranIran

In this research gasoil desalting was investigated from mass transfer point of view in an eductor liquid–liquid extraction column(eductor-LLE device).Mass transfer characteristics of the eductor-LLE device were evaluated and an empirical correlation was obtained by dimensional analysis of the dispersed phase Sherwood number.The Results showed that the overall mass transfer coefficient of the dispersed phase and extraction efficiency have been increased by increasing Sauter mean diameter(SMD)and decreasing the nozzle diameter from 2 to 1 mm,respectively.The effects of Reynolds number(R_(e)),projection ratio(ratio of the distance between venturi throat and nozzle tip to venturi throat diameter,Rpr),venturi throat area to nozzle area ratio(R_(th-n))and two phases flow rates ratio(R_(Q))on the mass transfer coefficient(K)were determined.According to the results,K increase with increasing Re and RQ and also with decreasing Rpr and R_(th-n).Semi-empirical models of drop formation,rising and coalescence were compared with our proposed empirical model.It was revealed that the present model provided a relatively good fitting for the mass transfer model of drop coalescence.Moreover,experimental data were in better agreement with calculated data with AARE value of 0.085.

关键词： Gasoil desalting Liquid-liquid extraction Eductor-LLE device Mass transfer coefficient extraction efficiency

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Effective rare earth extraction from Nd-Fe-B waste by liquid cuprum extraction method

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Journal of Rare Earths 2020年第12期38卷 1337-1343页

作者： Ke Xu Junru Xiao Zhongwu Liu School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China Dongguan Hyper Tech Co. Ltd.Dongguan 523808China

Recovery of rare earth(RE)elements from Nd-Fe-B waste is one of the ways to solve the problem of socalled RE-crisis,An alternative approach of extracting RE elements from Nd-Fe-B waste by molten Cu extraction based on liquid-solid diffusion and reaction is reported in this paper.The extraction process,product microstructure and extraction efficiency were systematically studied.The results show that the extraction rate of RE at 1200℃is about 20%higher than that at 1100℃.The enhanced extraction efficiency at 1200℃results from the fact that the liquid Fe and Fe2 B are not co-soluble with Cu,Reducing the mass ratio of Cu to waste and the size of the waste scraps is also beneficial to enhancing the separation of RE and Fe elements.In addition,the extraction time should be well controlled,for example,less than 2 h at 1100℃,in order to avoid the increased Fe content in the extracted product.Based on optimized process,the RE elements ca n be almost fully extracted from the waste.This work thus provides an effective method to recover the RE elements.

关键词： Nd-Fe-B waste Rare earth extraction Liquid extraction Scrap particles extraction efficiency

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Improved light extraction of GaN-based light-emitting diodes with surface-textured indium tin oxide electrodes by nickel nanoparticle mask dry-etching

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Chinese Physics B 2010年第6期19卷 551-555页

作者：何安和章勇朱学绘陈献文范广涵何苗 Institute of Optoelectronic Materials and Technology South China Normal University

GaN-based light-emitting diodes （LEDs） with surface-textured indium tin oxide （ITO） as a transparent current spreading layer were fabricated. The ITO surface was textured by inductively coupled plasma （ICP） etching technology using a monolayer of nickel （Ni） nanoparticles as the etching mask. The luminance intensity of ITO surface-textured GaN-based LEDs was enhanced by about 34% compared to that of conventional LED without textured ITO layer. In addition, the fabricated ITO surface-textured GaN-based LEDs would present a quite good performance in electrical characteristics. The results indicate that the scattering of photons emitted in the active layer was greatly enhanced via the textured ITO surface, and the ITO surface-textured technique could have a potential application in improving photoelectric characteristics for manufacturing GaN-based LEDs of higher brightness.

关键词： GaN-based light-emitting diodes nickel nanoparticle extraction efficiency surface roughening

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