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MXene/石墨烯纳米复合材料的制备及其在锂离子电池负极中的应用

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MXene/石墨烯纳米复合材料的制备及其在锂离子电池负极中的应用

作者： Rehman butt 中国科学院大学(中国科学院宁波材料技术与工程研究所)

学位级别：硕士

为应对全球能源危机,我们需要开发更加可靠的新能源储能设备,锂离子电池在这方面已被证明是最佳候选者。锂离子电池的容量可以通过电池设计和电极材料的开发来进一步提高。长期以来,石墨一直被用作锂离子电池的负极,但它的能量密度较低... 详细信息

为应对全球能源危机,我们需要开发更加可靠的新能源储能设备,锂离子电池在这方面已被证明是最佳候选者。锂离子电池的容量可以通过电池设计和电极材料的开发来进一步提高。长期以来,石墨一直被用作锂离子电池的负极,但它的能量密度较低。因此,迫切需要开发高容量、循环稳定的新一代负极材料。铌碳化物作为极少被研究的MXene系列成员,有很大潜力被用作高容量的锂离子电池负极材料。但是由于自堆叠的问题,导致其活性位点数目和可用表面积减小。在本论文研究中,我们制备了碳化铌与部分还原氧化石墨烯的复合材料。由于石墨烯片的引入,MXene片的层间距离增加,将其用作锂离子电池负极时,在0.1 A g的电流密度下循环500次之后,复合电极材料仍能保持270 ma h g的容量。此后,为了进一步改善材料的性能,我们通过静电吸附作用,制备了碳化铌与还原氧化石墨烯的多孔混合气凝胶。多孔结构不仅增加了可接触的表面积,而且增加了电解质离子嵌入的活性位点。rGO的添加不仅有助于解决MXene的自堆叠问题,而且还保持了复合材料的高导电性。将这种复合材料用作锂离子电池负极时,即使在1 Ag电流密度下循环1000次,仍然保有260 ma g h的容量。在本论文的研究中,我们利用石墨烯与铌碳化物组装成复合电极材料,克服了容量衰减的同时还具备高能量密度的特点,是一种具有良好应用前景的锂离子电池电极材料。

关键词：锂离子电池负极材料多孔结构 MXene 还原氧化石墨烯

Microstructure and mechanical properties of double-side friction stir welded 6082Al ultra-thick plates

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Journal of materials Science & Technology 2020年第6期41卷 105-116页

作者： C.Yang J.F.Zhang G.n.ma L.H.Wu X.M.Zhang G.Z.He P.Xue D.R.ni B.L.Xiao K.S.Wang Z.Y.ma Shenyang national Laboratory for materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China CRRC Changchun Railway Vehicles Co. Ltd.Changchun 130062China School of Metallurgical Engineering Xi’an University of Architecture and TechnologyXi’an 710055China

In the present work,80 mm thick 6082Al alloy plates were successfully double-side welded by friction stir welding(FSW).The relationship between the microstructures and mechanical properties was built for the double-side FSW butt joint with more attention paid to the local characteristic *** was shown that a phenomenon of microstructural inhomogeneity existed in the nugget zone(nZ)through the thickness *** grain size presented an obvious gradient distribution from the top to the bottom for each single-pass weld,and the microhardness values decreased from both surfaces to the middle of the *** lowest hardness zone(LHZ)exhibited a"hyperbolical"-shaped distribution extending to the middle of the *** tensile properties were obtained in the three sliced specimens of the FSW joint,and the joint coefficient reached about 70%which achieved the same level as the conventional FSW Al alloy *** element modeling proved that the"hyperbolical"-shaped heat affected zone(HAZ)was beneficial to resisting the strain concentration in the middle layer specimen which helped to increase the tensile *** on the analysis of the hardness contour map,tensile property and microstructural evolution of the joints,an Isothermal Softening Layer(ISL)model was proposed and established,which may have a helpful guidance for the optimization on the FSW of ultra-thick Al alloy plates.

关键词： Ultra-thick aluminum alloy plates Double-side friction stir welding Finite element model Microstructural inhomogeneity Mechanical properties

Role of endoscopic ultrasound for pre-intervention evaluation in early esophageal cancer

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World Journal of Gastrointestinal Endoscopy 2023年第6期15卷 447-457页

作者： Sartajdeep Kahlon Ali Aamar Zeeshan butt Shiro Urayama Department of Internal Medicine University of California-DavisSacramentoCA 95817United States Department of Internal Medicine Baystate Medical CenterSpringfieldMA 01199United States

BACKGROUnD Endoscopic ultrasound(EUS)stands as an accurate imaging modality for esophageal cancer staging,however utilization of EUS in early-stage cancer management remains *** of non-applicability of endoscopic interventions with deep muscular invasion with EUS in pre-intervention evaluation of early-stage esophageal cancer is compared to endoscopic and histologic *** To display the role of EUS in pre-intervention early esophageal cancer staging and how the index endoscopic features of invasive esophageal malignancy compare for prediction of depth of invasion and cancer *** This was a retrospective study of patients who underwent pre-resection EUS after a diagnosis of esophageal cancer at a tertiary medical center from 2012 to *** clinical data,initial esophagogastroduodenoscopy/biopsy,EUS,and final resection pathology reports were abstracted,and statistical analysis was conducted to assess the role of EUS in management *** Forty nine patients were identified for this *** T stage was concordant with histological T stage in 75.5%of *** determining submucosal involvement(T1a vs T1b),EUS had a specificity of 85.0%,sensitivity of 53.9%,and accuracy of 72.7%.Endoscopic features of tumor size>2 cm and the presence of esophageal ulceration were significantly associated with deep invasion of cancer on *** affected management from endoscopic mucosal resection/submucosal dissection to esophagectomy in 23.5%of patients without esophageal ulceration and 6.9%of patients with tumor sizents without both endoscopic findings,EUS identified deeper cancer and changed management in 4.8%(1/20)of *** EUS was reasonably specific in ruling out submucosal invasion but had relatively poor *** validated endoscopic indicators suggested superficial cancers in the group with a tumor sizend the lack of esophageal *** patients with these findi

关键词： Endoscopic ultrasound Esophageal early-stage cancer Endoscopic intervention Endoscopic indicators of invasive cancer Cancer intervention Endoscopy

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440MPa级HSLA钢焊缝低温韧性分析

焊接 2024年第1期 33-39页

作者：曾道平郑韶先安同邦马成勇兰州交通大学兰州730070 钢铁研究总院北京100081

采用自制的2种实心焊丝对440 MPa级HSLA钢进行了对接maG焊(80%Ar+20%CO_(2)),通过对比分析2种焊缝的显微组织和夹杂物尺寸及成分,对2种焊缝低温韧性出现显著差异的原因进行了阐释。结果表明,J1焊丝的焊缝由针状铁素体、侧板条铁素体、... 详细信息

采用自制的2种实心焊丝对440 MPa级HSLA钢进行了对接maG焊(80%Ar+20%CO_(2)),通过对比分析2种焊缝的显微组织和夹杂物尺寸及成分,对2种焊缝低温韧性出现显著差异的原因进行了阐释。结果表明,J1焊丝的焊缝由针状铁素体、侧板条铁素体、先共析铁素体和M-A组元组成,而J2焊丝的焊缝由针状铁素体和M-A组元组成;2种焊丝的焊缝中夹杂物的粒径分布、尺寸、数量和成分差异小,不是导致2种焊缝低温韧性出现显著差异的主要原因;与J1焊丝的焊缝相比,J2焊丝的焊缝中针状铁素体含量升高、M-A组元含量降低、条状和块状M-A组元占比降低,是导致其低温韧性显著优于J1焊丝的主要原因。

关键词： 440 MPa级HSLA钢显微组织针状铁素体 M-A组元低温韧性

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Color-selective holographic retroreflector array for sensing applications

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Light(Science & Applications) 2016年第1期5卷 241-249页

作者： Rajib Ahmed Ali K Yetisen Seok Hyun Yun Haider butt Microengineering and nanotechnology Laboratory School of EngineeringUniversity of BirminghamBirmingham B152TTUK Harvard Medical School and Wellman Center for Photomedicine Massachusetts General HospitalCambridgeMA 02139USA Harvard-MIT Division of Health Sciences and Technology Massachusetts Institute of TechnologyCambridgeMA 02139USA

Corner cube retroreflectors(CCRs)have applications in sensors,image processing,free space communication and wireless *** ability to construct low-loss wavelength filters embedded in CCRs can enable the development of wavelength multiplexing,tunable lasers and photonic integrated *** we created an~10-μm-thick holographic corner cube retroreflector(HCCR)array that acted as a color-selective wavelength filter and diffracted light at broad ***-resolved spectral measurements showed that the Bragg peak of the diffracted light from the HCCR array could be tuned from 460 to 545 nm by varying the incident *** HCCR array also exhibited a wavelength-selective tuning capability based on the rotation angle in the visible *** projected holographic images with the rotational property in the far *** utility of the HCCR was demonstrated as optical temperature and relative humidity sensors that produced a visible colorimetric response for rapid diagnostics.

关键词： Bragg gratings corner cube retroreflectors diffraction optics holography sensors

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压力管道对接焊缝焊趾应力集中研究

江西科学 2024年第4期42卷 809-812,875页

作者：封小亮马括刘课秀广州特种承压设备检测研究院广州510000

国标GB/T 19624—2019环焊缝平面缺陷的安全评价主要考虑轴向膜应力与弯曲应力之和,并未考虑焊缝应力集中效应对膜应力的影响行为。基于ASME VIII焊缝疲劳的结构应力分析方法,采用ABAQUS分析了14 mm板厚的焊缝余高h、焊缝宽度b等对对接... 详细信息

国标GB/T 19624—2019环焊缝平面缺陷的安全评价主要考虑轴向膜应力与弯曲应力之和,并未考虑焊缝应力集中效应对膜应力的影响行为。基于ASME VIII焊缝疲劳的结构应力分析方法,采用ABAQUS分析了14 mm板厚的焊缝余高h、焊缝宽度b等对对接焊缝应力集中的影响规律。结果表明,当宽度b一定,焊缝结构应力集中系数K_(m)值随余高h增加而增大,当余高h到达一定值后,K_(m)值基本恒定,此时K_(m)值最大值取决于宽度b,并据此提出了在特定余高h及宽度b区间内K_(m)与宽度b之间函数关系式K_(m)=0.97+0.021b,研究内容对于含缺陷压力管道安全评价和对接焊缝的疲劳分析具有重要工程指导价值。

关键词：安全评价膜应力对接焊缝结构应力

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Bifunctional catalysts of Co3O4@GCn tubular nanostructured （TnS） hybrids for oxygen and hydrogen evolution reactions

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nano Research 2015年第11期8卷 3725-3736页

作者： muhammad Tahir nasir mahmood Xiaoxue Zhang Tariq mahmood Faheem. K. butt Imran Aslam M.Tanveer Faryal Idrees Syed Khalid Imran Shakir Yiming Yan Jijun Zou Chuanbao Cao Yanglong Hou Research Centre of materials Science Beijing Institute of Technology Beijing 100081 China Department of materials Science and Engineering Peldng University Beijing 100081 China Beijing Key Laboratory for Chemical Power Source and Green Catalyst School of Chemical Engineering and Environment Beijing Institution of Technology Beijing 100081 China Sustainable Energy Technologies (SET) center building no 3 Room 1c23 College of Engineering King Saud University PO BOX 800 Riyadh 11421 Kingdom of Saudi Arabia Key Laboratory for Green Chemical Technology of the Ministry of Education School of Chemical Engineering and Technology Tianjin University Collaborative Innovative Center of Chemical Science and Engineering (Tianjin) Tianjin 300072 China

Catalysts for oxygen and hydrogen evolution reactions （OER/HER） are at the heart of renewable green energy sources such as water splitting. Although incredible efforts have been made to develop efficient catalysts for OER and HER, great challenges still remain in the development of bifunctional catalysts. Here, we report a novel hybrid of Co3O4 embedded in tubular nanostructures of graphitic carbon nitride （GCn） and synthesized through a facile, large-scale chemical method at low temperature. Strong synergistic effects between Co3O4 and GCn resulted in excellent performance as a bifunctional catalyst for OER and HER. The high surface area, unique tubular nanostructure, and composition of the hybrid made all redox sites easily available for catalysis and provided faster ionic and electronic conduction. The Co3O4@GCn tubular nanostructured （TnS） hybrid exhibited the lowest overpotential （0.12 V） and excellent current density （147 ma/cm^2） in OER, better than benchmarks IrO2 and RuO2, and with superior durability in alkaline media. Furthermore, the Co3O4@GCn TnS hybrid demonstrated excellent performance in HER, with a much lower onset and overpotential, and a stable current density. It is expected that the Co3O4@GCn TnS hybrid developed in this study will be an attractive alternative to noble metals catalysts in large scale water splitting and fuel cells.

关键词： carbon nitride cobalt oxide bifunctional catalyst oxygen evolution reaction hydrogen evolution reaction

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柔性件对接点焊装配偏差有限元分析

制造技术与机床 2024年第5期 160-166页

作者：耿浩然徐旭松刘文君薛耀阳马家亮江苏理工学院机械工程学院江苏常州213001

文章针对柔性件对接点焊产生的装配偏差问题,在完成“n-2-1”柔性定位的基础上,首先采用影响系数法对柔性件装配偏差进行建模,分析焊接时产生的装配偏差;其次,利用Ansys进行有限元仿真计算,研究焊点数量以及焊接热对装配偏差产生的影响... 详细信息

文章针对柔性件对接点焊产生的装配偏差问题,在完成“n-2-1”柔性定位的基础上,首先采用影响系数法对柔性件装配偏差进行建模,分析焊接时产生的装配偏差;其次,利用Ansys进行有限元仿真计算,研究焊点数量以及焊接热对装配偏差产生的影响;最后,以车身门框焊装为例进行了实例研究,该方法可适用于柔性件在考虑焊接热影响下多焊点装配偏差分析。

关键词：柔性件有限元分析焊接热变形

InP based DFB laser array integrated with MMI coupler

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Science China Technological Sciences 2013年第3期56卷 573-578页

作者： ZHU HongLiang ma Li LIAnG Song ZHAnG Can WAnG BaoJun ZHAO LingJuan WAnG Wei Key Laboratory of Semiconductor materials Science Institute of SemiconductorsChinese Academy of Sciences Department of Electronic Engineering Tsinghua University

The techniques used for the fabrication of photonic integrated circuit(PIC) chip are introduced *** a four channel DFB laser array integrated with MMI coupler and semiconductor optical amplifier(SOA) fabricated with b... 详细信息

关键词： PIC DFB laser array MMI monolithic integration