Fluorine substitution position effects on spiro(fluorene-9,9’-xanthene) cored hole transporting materials for high-performance planar perovskite solar cells

Fluorine substitution in molecular design has become an effective strategy for improving the overall performance of organic photovoltaics.In this study,three low-cost small molecules of spiro-linked hole transporting materials(SFX-O-2 F,SFX-m-2 F,and SFX-p-2 F) endowed with two-armed t rip he ny la mine moieties were synthesized via tuning of the fluorine substitution position,and they were employed for use in highly efficient perovskite solar cells(PSCs).Despite the fluorine substitution position playing a negligible role in the optical and electrochemical properties of the resulting small molecules,the photovoltaic performance thereof was observed to vary significantly.The planar n-i-p PSCs based on SFX-m-2 F demonstrated superior performance(18.86%) when compared to that of the corresponding SFX-o-2 F(9.7%) and SFX-p-2 F(16.33%) under 100 mW cm^(-2) AM1.5 G solar illumination,which is competitive with the performance of the benchmark spiro-OMeTAD-based device(18.98%).Moreover,the SFX-m-2 Fbased PSCs were observed to be more stable than the spiro-OMeTAD-based devices under ambient conditions.The improved performance of SFX-m-2 F is primarily associated with improved morphology,more efficient hole transport,and extraction characteristics at the perovskite/HTM interface.This work demonstrated the application of fluorination engineering to the tuning of material film morphology and charge transfer properties,showing the promising potential of fluorinated SM-HTMs for the construction of low-cost,high-efficiency PSCs.

Impact of Planting Position and Planting Material on Root Yield of Cassava （Manihot esculenta Crantz）

Cassava （Manihot esculenta Crantz） is a perennial woody shrub with an edible root, which grows in tropical and subtropical areas of the world. In Africa, cassava provides a basic daily source of dietary energy. It plays an important role in food security and incomes of many rural households in the southern Ethiopia. However, information available on production practices of cassava for the region is insufficient. Hence, field experiment was conducted at Awassa Agricultural Research Center for two successive cropping seasons from 2004 to 2006 to investigate the response of cassava to planting position and planting material. The treatments used were three planting positions （slant, vertical and horizontal） and five planting materials （main stem top part, main stem middle part, main stem bottom part, branch stake top part and branch stake bottom part） were combined in factorial arrangement and laid out in randomized complete block design with three replications. The result revealed that root yield was significantly （P 〈 0.05） affected by the interaction effects of the planting position and planting material. The highest yield （25.2 ton ha^-1） was obtained from the main stem top part planted in slant position whereas the least yield （6.5 ton ha^-1） was obtained from main stem bottom part planted in horizontal position. Based on the findings of this study, areas like Awassa with moderate rainfall slant and vertical planting of main stem top and middle parts could be used as planting material.

C≡N-based carbazole-arylamine hole transporting materials for perovskite solar cells: Substitution position matters

Hole transporting materials(HTMs)containing passivating groups for perovskite materials have attracted much attention for efficient and stable perovskite solar cells(PSCs).Among them,C≡N-based molecules have been proved as efficient HTMs.Herein,a series of novel C≡N functionalized carbazole-arylamine derivatives with variable C≡N substitution positions(para,meta,and ortho)on benzene-carbazole skeleton(on the adjacent benzene of carbazole)were synthesized(p-HTM,m-HTM and o-HTM).The experimental results exhibit that the substitution positions of the Ctriple bondN unit on HTMs have minor difference on the HOMO energy level and hydrophobicity.m-HTM has a relatively lower glass transition temperature compared with that of p-HTM and o-HTM.The functional theory calculations show that the C≡N located on meta position exposed very well,and the exposure direction is also the same with the methoxy.Upon applying these molecules as HTMs in PSCs,their device performance is found to sensitively depend on the substitution position of the C≡N unit on the molecule skeleton.The devices using m-HTM and o-HTM exhibit better performance than that of p-HTM.Moreover,m-HTM-based devices exhibit better light-soaking performance and long-term stability,which could be resulted from better interaction with the perovskite according to DFT results.Moreover,we further prepared a HTM with two C≡N units on the symmetrical meta position of molecular skeleton(2m-HTM).Interestingly,2m-HTM-based devices exhibit relatively inferior performance compared with that of the m-HTM,which could be resulted from weak negative electrical character of C≡N unit on 2m-HTM.The results give some new insights for designing ideal HTM for efficient and stable PSCs.

Preparation of layered Li(Ni_(1/3)Co_(1/3)Mn_(1/3))O_2 as positive material for lithium-ion secondary battery

The uniform layered Li(Ni1/3Co1/3Mn1/3)O2 cathode material for lithium-ion secondary batteries were synthesized by using(Ni1/3Co1/3Mn1/3)(OH)2 synthesized by a liquid phase co-precipitated method as precursors and with NiSO4,CoSO4,MnSO4 and NH3·H2O as raw materials. The influence of the preparation conditions such as precursors preparation,calcinations temperature and calcinations time on the structural and electrochemical properties of the Li(Ni1/3Co1/3Mn1/3)O2 were systematicelly studied. The result of XRD shows the I003/I104 value of the Li(Ni1/3Co1/3Mn1/3)O2 powder synthesized at 950 ℃ for 10 h is 1.26,which illustrates the well-ordered layer-structure. The average particle size of uniform Li(Ni1/3Co1/3Mn1/3)O2 powder is about 400 nm in diameter as observed by scanning electron microscopy. The first discharge capacity of Li(Ni1/3Co1/3Mn1/3)O2 electrode is 174.6 mA·h/g at 16 mA/g between 2.8 V and 4.5 V versus Li at room temperature,and the capacity retention is 95.2% of the initial discharge capacity after 50 cycles at 32 mA/g.

Nonlinear magneto-electric response of a giant magnetostrictive/piezoelectric composite cylinder

In this study, we investigate the nonlinear cou- pling magneto-electric （ME） effect of a giant magnetostric- tive/piezoelectric composite cylinder. The nonlinear consti- tutive relations of the ME material are taken into account, and the influences of the nonlinear material properties on the ME effect are investigated for the static and dynamic cases, respectively. The influences of different constraint conditions on the ME effect are discussed. In the dynamic case considering nonlinear material properties, the double frequency ME response （The response frequency is twice the applied magnetic frequency） is obtained and discussed, which can be used to explain the experiment phenomenon in which the input signal with frequency f is converted to the output signal with 2f in ME laminated structures. Some calculations on nonlinear ME effect are conducted. The obtained results indicate that the nonlinear material properties affect not only the magnitude of the ME effect in the static case but also the ME response frequency in the dynamic case

CHARACTERIZATION OF COBALT(Ⅱ)-PHTHALOCYANINE-METAL IRON COMPOSITES FOR MAGNETORHEOLOGICAL FLUIDS

Magnetorheological suspension based on 20 (v/V) % CoPc-iron composite particles dispersed in sili-cone oil have been obtained, which exhibited dynamic shear stress up to 2000Pa upon application of external magnetic field at 1300 Oe. The response is faster than 0. 15 -with superior reversibility of changes in viscosity induced by external magnetic field at above 12. 5℃. Further, it was found that the MR fluid is in possession of long-term stability a-gainst sedimentation.

CAVITATION BIFURCATION FOR COMPRESSIBLE ANISOTROPIC HYPERELASTIC MATERIALS

The e?ect of material anisotropy on the bifurcation for void formation in anisotropic compressible hyperelastic materials is examined. Numerical solutions are obtained in an anisotropic sphere, whose material is transversely isotropic in the radial direction. It is shown that the bifur- cation may occur either to the right or to the left, depending on the degree of material anisotropy. The deformation and stress contribution in the sphere before cavitation are di?erent from those after cavitation. The stability of solutions is discussed through a comparison of energy.

Synthesis and characterization of LiFePO_4/C composite used as lithium storage electrodes

LiFePO4/C composites with good rate capability and high energy density were prepared by adding sugar to the synthetic precursor. A significant improvement in electrode performance was achieved. The resulting carbon contents in the sample 1 and sample 2 are 3.06% and 4.95%（mass fraction）, respectively. It is believed that the synthesis of LiFePO4 with sugar added before heating is a good method because the synthesized particles having uniform small size are covered by carbon. The performance of the cathodes was evaluated using coin cells. The samples were characterized by X-ray diffraction and scanning electron microscope observation. The addition of carbon limits the particles size growth and enables high electron conductivity. The LiFePO4/C composites show very good electrochemical performance delivering about 142 mAh/g specific capacity when being cycled at the C/10 rate. The capacity fade upon cycling is very small.

Holographic alloy positioning design system and holographic network phase diagrams of Au-Cu system

Taking Au?Cu system as an example, three discoveries and two methods were presented. First, a new way for boosting sustainable progress of systematic metal materials science (SMMS) and alloy gene engineering (AGE) is to establish holographic alloy positioning design (HAPD) system, of which the base consists of measurement and calculation center, SMMS center, AGE center, HAPD information center and HAPD cybernation center; Second, the resonance activating-sychro alternating mechanism of atom movement may be divided into the located and oriented diffuse modes; Third, the equilibrium and subequilibrium holographic network phase diagrams are blueprints and operable platform for researchers to discover, design, manufacture and deploy advanced alloys, which are obtained respectively by the equilibrium lever numerical method and cross point numerical method of isothermal Gibbs energy curves. As clicking each network point, the holographic information of three structure levels for the designed alloy may be readily obtained: the phase constitution and fraction, phase arranging structure and properties of organization; the composition, alloy gene arranging structure and properties of each phase and the electronic structures and properties of alloy genes. It will create a new era for network designing advanced alloys.

Sucrose pyrolysis assembling carbon nanotubes on graphite felt using for vanadium redox flow battery positive electrode

In the present paper, multi-walled carbon nanotubes（MWCNTs） are successfully assembled on graphite felt（GF） using sucrose pyrolysis method for the first time. The in situ formed pyrolytic carbon is chosen as the binder because it is essentially carbon materials as well as CNTs and GF which has a natural tendency to achieve high bonding strength and low contact resistance. The MWCNTs/GF electrode is demonstrated to increase surface area, reduce polarization, lower charge transfer resistance and improve energy conversion efficiency comparing with GF. This excellent electrochemical performance is mainly ascribed to the high electro-catalytic activity of MWCNTs and increasing surface area.

Mesoporous composite of LiFePO_4 and carbon microspheres as positive-electrode materials for lithium-ion batteries

Mesoporous LiFePO4/C microspheres consisting of LiFePO4 nanoparticles are successfully fabricated by an eco-friendly hydrothermal approach combined with high-temperature calcinations using cost-effective LiOH and Fe3＋ salts as raw materials.In this strategy,pure mesoporous LiFePO4 microspheres,which are composed of LiFePO4 nanoparticles,were uniformly coated with carbon（1.5nm）.Benefiting from this unique architecture,these mesoporous LiFePO4/C microspheres can be closely packed,having high tap density.The initial discharge capacity of LiFePO4/C microspheres as positive-electrode materials for lithium-ion batteries could reach 165.3 mAh/g at 0.1 C rate,which is notably close to the theoretical capacity of LiFePO4 due to the large BET surface area,which provides for a large electrochemically available surface for the active material and electrolyte.The material also exhibits high rate capability（100 mAh/g at 8 C） and good cycling stability（capacity retention of 92.2%after 400 cycles at 8 C rate）.

Positive temperature coefficient of resistivity effects of semiconducting (Bi(1/2)Na(1/2)) TiO_3-CaTiO_3-BaTiO_3 ceramics sintered in air atmosphere

Y^3＋-doped （Bi 1/2 Na 1/2） TiO 3-CaTiO 3-BaTiO 3 （BNCBT） positive temperature coefficient of resistivity （PTCR） ceramics sintered in air atmosphere were investigated in this study. （Bi 1/2 Na 1/2） TiO 3 （BNT） component can remarkably increase the onset temperature T c of PTCR ceramics with the expense of the resistivity R 25 increase. CaTiO 3 （9–27 mol%） component can decrease the resistivity, and adjust the effects of BNT phase on the T c point. For the sample containing 3 mol% CaTiO 3 , T c raises from 122 ℃ to 153 ℃ when only 0.6 mol% BNT added, while for the ones with higher CaTiO 3 content （9–27 mol%）, T c is only increased by a rate of 8–9℃/1.0 mol% BNT. The effects of BNT and CaTiO 3 components on R25/Rmin （negative temperature coefficient effect） are also discussed.

取代基位置对2,4-二苯基吡啶类铱磷光配合物光物理性能的影响

铱磷光配合物具有高的发光效率、良好的热稳定性和发光颜色容易调节等优势,在有机发光二极管(OLED)、电化学发光池(LEC)、光催化、肿瘤诊断和传感器等领域有着重要的应用前景,是综合性能最优的电致磷光配合物。其颜色调控主要通过改变主配体和辅助配体的化学结构来实现,如通过改变配体的共轭程度、在配体上引入具有不同供/吸电子能力的取代基、在不同位置引入相同的取代基等方式可以实现发光颜色的调节,其中取代基的位置对铱磷光配合物光物理性能影响的研究较少。研究甲基处于不同取代位置对铱磷光配合物光物理性能的影响,以甲基处于2位和4位或3位和5位的2,4-二苯基吡啶为主配体、2,2,6,6-四甲基庚二酮为辅助配体,合成出2个新的铱磷光配合物(2,4-2Me-dppy)_(2)Ir(tmd)和(3,5-2Me-dppy)_(2)Ir(tmd)。通过元素分析、核磁共振谱和单晶X射线衍射等测试了配合物的组成和空间结构,两个配合物均呈稍微扭曲的八面体构型,空间群分别为C 12/c 1和P-1,晶系分别为单斜和三斜;通过热重分析研究了配合物的热稳定性,两个配合物均具有较好的热稳定性,热分解温度分别为307和318℃;通过紫外可见光谱和光致发光光谱研究了配合物的光物理性能,两个配合物在溶液中发射波长分别为545和572 nm,溶液中量子产率分别为70%和92%。进一步探讨了取代基位置对铱磷光配合物光物理性能的影响,研究发现:甲基所处的位置对2,4-二苯基吡啶类铱磷光配合物的发光颜色和发射波长有着显著的影响。与甲基处于2位和4位得到的铱磷光配合物相比,甲基处于3位和5位时得到的铱配合物的发射波长产生了明显的红移,为纯正的黄光发射,是一种潜在的黄光材料,并有望在OLED照明中得到应用。

主动悬架直线电机温升-电磁特性分析与优化设计

为了提高主动悬架系统中直线电机的工作性能,以一种圆筒型永磁同步直线电机为研究对象,对其进行特性分析与结构优化。以某SUV为例,构建了其主动悬架系统的多体动力学模型,仿真确定了电机的总体设计指标与初始结构。采用有限元方法建立了考虑材料热属性变化的直线电机温升模型,分析了不同行驶车速下的温升分布及其对直线电机电磁特性的影响。结果发现:电机温升直接影响输出推力与绕组损耗,抑制温升有助于减小绕组损耗,但推力波动会随之上升。根据磁-热耦合特性分析结果,以空载定位力和绕组温升为优化目标,进行了参数敏感度分析,并采用响应面法对直线电机结构参数进行多目标优化。结果表明:优化后直线电机的空载定位力减小了7.5%,绕组损耗降低了17.5%,绕组温升降低了11.02%,电机工作性能显著提升。试制了永磁同步直线电机样机,并进行了台架测试,实验与仿真误差均在5%以内,验证了结构和优化方案的有效性。

自动钻铆末端双目高精定位系统设计

设计了基于自动钻铆末端的双目高精定位系统。首先对视觉定位需求进行分析,设计双目视觉系统结构参数,基于视觉光源去除复合材料背景纹理;其次对轮廓进行提取拟合,预处理标定后结合ESPCN和Canny算子进行亚像素边缘提取,利用改进最小二乘法拟合计算圆心坐标;最后对视觉定位系统进行精度验证。结果表明:平面定位误差小于0.02mm,深度定位误差小于0.04mm,满足钻铆机器人的视觉测量要求。

优化类型定位背景下高职新型教材开发的实践样态与框架优化

新型教材建设是现阶段撬动职业教育课程与教学改革、实现优质资源共享、提升人才培养质量、推动高质量发展的重要基础。当前高职院校的新型教材开发实践初见成效,但在概念认知力、开发能力、开发规范性、改革可持续性等方面存在问题。职业教育的类型属性是新型教材开发的逻辑起点,开发高质量的新型教材是现阶段优化职业教育类型定位的应有之义。类型属性下的高职新型教材开发应注重模式应用的适切性,内容选择的职业性、实践性、先进性与思想性,内容组织的重构逻辑、工作逻辑与整合逻辑,以及呈现方式的纸数融合化。基于实然性问题样态与应然性基本遵循,可从健全工作机制、改进技术路径、细化管理策略等维度探索优化高职新型教材开发的实践框架。

废旧锂离子电池正极材料有价金属回收研究现状

近年来,随着“碳达峰”、“碳中和”等目标的提出,新能源电动汽车发展迅速,锂离子电池的需求量也随之剧增,而大量锂离子电池的使用也必将迎来锂离子电池爆发式退役,从而大量的废旧锂离子电池有待回收。锂电池大致可分为三元锂电池、磷酸铁锂电池、钴酸锂电池、锰酸锂电池四大类,目前主要的回收方法有火法冶金技术、湿法冶金技术。本文叙述了近年来上述四大类锂离子电池正极目标金属的回收研究现状,从流程的难易程度、目标金属的提取效率以及对环境是否产生污染性气体或废液等多个方面来分析各项工艺。最后,对不同冶金工艺的优缺点进行总结以及未来的前景进行展望。

氟化碳(CF_(x))材料在锂原电池中的研究进展与应用

CF_(x)作为一种重要的正极材料,在锂原电池中具有高能量密度、长贮存寿命和优异的安全性等优点。近年来,研究人员通过研究Li/CF_(x)的工作机理,揭示了CF_(x)材料目前存在的问题,并针对这些问题进行了一系列的改性处理,如等离子体处理、表面包覆、原子掺杂等。此外,研究人员还通过表面脱氟、纳米尺度工程等手段,改变表面结构从而提升导电性和锂离子传输速率,进一步提高了其能量密度。这些研究成果为CF_(x)在锂原电池中的应用提供了新的思路和途径。主要介绍了Li/CF_(x)电池的工作机理及CF_(x)材料目前存在的问题,针对CF_(x)材料的改性方法做了总结分析,并对Li/CF_(x)电池在航空航天、国防军事等领域的应用做了详细介绍和展望。

面向欧盟《电池和废电池法规》动力电池碳足迹的减排路径与情景

2023年8月17日,欧盟《电池和废电池法规》(简称新《电池法》)在欧盟正式生效,并引入电池护照概念。根据该法规,从2025年2月18日起,动力电池需提供电池的碳足迹信息,以突破欧盟贸易壁垒,促进国内动力电池的出口。本文以NCM三元5系电池为研究对象,对动力电池的碳足迹进行了梳理与分析,同时按照欧盟新《电池法》的要求,分析了在不同情景模式下电池的碳足迹减排情况。结果发现:①动力电池的碳排放减排关键在于正极材料,其碳排放占电芯原材料总碳排放的58%,其中正极前驱体在正极材料碳排放中的占比高达85%,其次是能耗碳排放,占电芯总碳排放的20%;②在使用可再生能源的情况下,5系电芯产品的碳足迹排放最低可以减少2.73%,最高可减少13.69%,其次仅使用正极再生材料减排,则5系电芯产品的碳足迹排放最低可减少1.81%,最高可减少7.86%;③在正极再生材料与可再生能源结合使用的情况下,5系电芯产品的碳足迹排放最低可减少4.55%,最高可减少21.55%。

锌离子电容器正极材料设计策略与研究进展

锌离子电容器是一种由电池型负极和电容型正极组成的混合型超级电容器,具有高能量密度、高功率密度、高安全性、低成本等优点。锌离子电容器能量密度仍受限于正极材料的储能能力,因此,如何设计高比电容的正极材料是提高其能量密度的关键。本文首先对锌离子电容器的发展历程、结构和原理进行了概述,并分析了限制锌离子电容器应用的原因;其次,系统归纳了典型碳基材料和赝电容材料作为正极材料的器件性能及其优点与不足;再次,选取代表性研究工作重点总结了纳米结构设计、复合材料构建、杂原子掺杂三种正极材料设计策略及研究进展;最后,对正极材料的发展前景进行了展望,具体指出深入研究和发现新的电化学机理、开发新型高性能正极材料、探索有效的碳材料改性策略和研制功能性(如柔性)电极材料等研究方向,为制备出具有优异电化学性能的正极材料提供重要思路。