Material Utilization Ratio Research Articles

Large-area thin film deposition technologies for fabricating hybrid perovskite solar cells

Organic-inorganic hybrid perovskite solar cells have attracted tremendous research interests due to their amazing light to electric power conversion efficiencies (PCEs). In the past four years, the PCE of perovskite solar cells has significantly increased up to 22.1%, which outperforms several other types of third-generation solar cells and becomes the most promising candidate to compete with the traditional silicon-based solar cells. This result is mainly owing to some excellent properties of the hybrid perovskite active layer, such as a high absorption coefficient, an appropriate band gap and a long carrier diffusion length. Nevertheless, most of the reported high efficiencies were only achieved with very small active areas in the range of 0.03 to 0.2cm2, which is likely to cause measurement errors. What is worse, the material utilization ratio is only 1% during film deposition, hindering the industrial production of perovskite solar cells in the future. Therefore, a large-scale production process has become a big challenge to realize the purpose of commercial applications. To date, the best certified PCE of 19.6% has been obtained with an active area exceeding 1cm2. The most important aspect is fabricating large-area uniform, pinhole-free and large crystal grain perovskite thin films for scaling up high PCE perovskite solar cells. To realize the purpose of large-area, high-quality perovskite film fabrication, a range of thin film fabrication techniques have been proposed, including spin-coating, vacuum flash-assisted solution process (VASP), doctor blading, slot-die coating, inkjet printing, spray coating, vapor assisted deposition and soft-cover deposition. This review aims at giving an overview of these thin film deposition techniques for the processing of perovskite thin film fabrication. By comparing the film quality and material utilization ratio corresponding to different film deposition methods, the studies on perovskite thin film fabrication techniques are summarized. Among these techniques, spin-coating has been widely used in laboratory for perovskite film fabrication, but the material utilization ratio is usually less than 1%, hindering the fabrication of perovskite film with large-area. Spin-coating combined with VASP exhibits an amazing result for high-quality perovskite film fabrication, but it still has a low material utilization ratio in spin-coating process. Other techniques, like doctor blading, slot-die coating and inkjet printing are suitable for large-area perovskite film fabrication with high material utilization ratio. Spray coating and soft-cover deposition also have shown great potential for large-area perovskite film fabrication. The PCEs of perovskite solar cells have reached 13% and 17% with an active area exceeding 1cm2, respectively. Particularly, a high-quality perovskite film with a large-area of 51cm2 was obtained by soft-cover deposition, which made this technique more promising for the development of perovskite solar cells in the future. Based on this review, we suggest that VASP is a suitable technique for depositing high-quality large-area perovskite film. It would be a promising technique to combine VSAP with other techniques, such as doctor blading, inkjet printing, etc., to enhance material utilization ratio for large-scale perovskite solar cells. In addition, some simpler and lower-cost techniques should be developed for the fabrication of perovskite solar cells in the future.

An efficient α-MnO2 nanorods forests electrode for electrochemical capacitors with neutral aqueous electrolytes

In this work, a facile and novel approach is presented to maintain stoichiometry, to achieve stable nanostructure and high surface area manganese oxide (α-MnO2). The synthesis of α-MnO2 nanorods forest has been carried out using reactive DC magnetron sputtering technique without use of surfactant/wet chemical procedure. The structural parameters, vibrational response and surface morphology of the α-MnO2 nanorods are characterized using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform Infrared spectroscopy (FT-IR), X-ray Photoluminescence spectroscopy (XPS), Field emission scanning electron microscopy (FE-SEM), Transmission electron miscopy (TEM) and BET surface area. The α-MnO2 nanorods have smooth surface and uniform diameters. The high surface area with lower lattice energy of poly nano-crystalline structure is expected to enhance the utilization ratio of electrode materials and facile de-intercalation process. The Mn-O-Mn bonded, MnO6 octahedral based and the well-developed tetragonal α-MnO2 with (2×2) tunnel is obtained. The mesopores in α-MnO2 provide wide channels, which is extremely suitable to transport ions into micropores present in α-MnO2. The electrochemical measurements are performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD) techniques. The MnO2 electrode exhibits high specific capacitance (346Fg−1 at 0.71Ag−1 in 1M aqueous Na2SO4) and good cycling stability (86.6% retention after 1500 cycles). The present approach opens a new avenue to design an efficient chemical reaction free nanorods.

Novel 6/7 Stator/Rotor Hybrid Excitation Doubly Salient Permanent Magnet Machine

One novel 6/7 stator/rotor hybrid excitation-biased flux permanent magnet machine (HE-BFPMM) is proposed in this paper. First, it discusses the new structure and operation principle in detail. Then, one improved design optimization technique is proposed to refine the HE-BFPMM based on a 2-D finite-element algorithm. Afterward, a comprehensive electromagnetic performance comparison between HE-BFPMM and original 6/7 stator/rotor BFPMM (ORI-BFPMM) has been made quantitatively by the premise of constant out radius and axial length. It indicates that, compared with ORI-BFPMM, the HE-BFPMM can demonstrate much higher no-load back electromotive force, lower torque ripple, higher PM material utilization ratio, and stronger flux-weakening capability.

3D Simulation on the Internal Distributed Properties of Lithium-Ionbattery with Planar Tabbed Configuration

Lithium-ion batteries have promoted the rapid developments of hybrid and electric vehicles due to their high energy, power density, and long lifetime [1]. Meanwhile, advanced hybrid and electric vehicles accelerate lithium-ion cells to be large sized [2].With the increase of battery cell size, the inhomogeneity of battery also increases, which exists not only between the batteries, but also inside a single battery. The inhomogeneity between batteries mainly refers to the difference in the battery pack. The main indicators are inconsistent battery voltage, internal resistance, capacity, and state of charge [3]. This inhomogeneity will lead certain cells to be the state of long-term over-charged or over-discharged, thus not only shortening the battery life, but also even leading to the combustion or explosion of batteries. The inhomogeneity inside a single battery mainly refers to the non-uniform distribution of the electrochemical reaction rate, current density, active material utilization ratio, and the electrolyte concentration in the electrode plate. The main damage of this inhomogeneity is the inhomogeneity of physicochemical properties such as stress gradient on the electrode plate [4]. In long cycling process, large gradient may lead to high diffusion induced stress (DIS), cause particle fracture and reduce battery capacity [5]. The inhomogeneity between batteries can be reduced or eliminated by the automatic production of battery and equalization module of battery management system (BMS). However, the inhomogeneity inside a single battery is difficult to be characterized or measured because of the sealed battery packaging. In this paper, a validated three-dimensional (3D) model on the electrode plate level of a lithium-ion battery was developed for a commercial type LP12100115 prismatic power LiFePO4/graphite battery (10 Ah) by coupling mass, charge, and energy conservations, as well as electrochemical kinetics. This model can intuitively show the space and time distribution characteristics of the internal electrochemical properties of the lithium-ion battery such as the transient distribution of electric potential, over-potential, state of charge, current density and lithium-ion concentration. The extraction of these distribution characteristics can significantly affect the design and optimization of large lithium-ion batteries.

Laser fabrication nanocrystalline coatings using simultaneous powders/wire feed

Laser melting deposition (LMD) fabrication is used to investigate feasibilty of simultaneously feeding TC17 wire and the Stellite 20–Si3N4–TiC–Sb mixed powders in order to increase the utilization ratio of materials and also quality of LMD composite coatings on the TA1 substrate. SEM images indicated that such LMD coating with metallurgical joint to substrate was formed free of the obvious defects. Lots of the ultrafine nanocrystals (UNs) were produced, which distributed uniformly in some coating matrix location, retarding growth of the ceramics in a certain extent; UNs were intertwined with amorphous, leading the yarn-shape materials to be produced. Compared with substrate, an improvement of wear resistance was achieved for such LMD coating.

자유단조공법을 통한 중공형 메인샤프트 제조공정에 관한 연구

The main shaft is one of the key components connecting the rotor hub and gear box of a wind power generator. Typically, main shafts are manufactured by open die forging method. However, the main shaft for large MW class wind generators is designed to be hollow in order to reduce the weight. Additionally, the main shafts are manufactured by a casting process. This study aims to develop a manufacturing process for hollow main shafts by the open die forging method. The design of a forging process for a solid main shaft and hollow shaft was prepared by an open die forging process design scheme. Finite element analyses were performed to obtain the flow stress by a hot compression test at different temperature and strain rates. The control parameters of each forging process, such as temperature and effective strain, were obtained and compared to predict the suitability of the hollow main shaft forging process. Finally, high productivity reflecting material utilization ratio, internal quality, shape, and dimension was verified by the prototypes manufactured by the proposed forging process for hollow main shafts.

Soft-cover deposition of scaling-up uniform perovskite thin films for high cost-performance solar cells

A large area perovskite film with less structural defects and a high material utilization ratio was formed by a continuous solution processing method, soft-cover deposition.

Determination of localized stresses in the shell above anchor bolt chairs attachments of anchored storage tanks

Anchor bolt chairs are attachments widely used to control the overturning stability of storage tanks subjected to external and internal forces. This paper discusses three different procedures based on mathematical equations, stress linearization and stress extrapolation to determine the localized stresses occurring in the shell above the chairs due to wind load. Several finite element models were built to study the effect of four different parameters such as the tank height, the tank diameter, the shell thickness and the anchor chair height. The results of the three methods are compared in terms of the localized stresses obtained from each one as well as in terms of the utilization ratio of the shell material.

열간자유단조와 링롤링공법을 이용한 풍력발전기용 도아프레임 개발

The mechanical components for wind turbines are mainly manufactured using open-die forging. This research introduces an advanced forging method to produce the door frame of the tubular wind turbine tower. The advantages of this new forging method are an increase in the raw material utilization ratio and a reduction in energy cost. In the conventional method, the door frame is hot forged with a hydraulic press and amounts of material are machined out because of the shape difference between the forged and final machine products. The proposed forging method is composed of hot forging and ring rolling processes to increase the material utilization ratio. The effectiveness of this new forging method is deeply related to the ring rolled blank dimension before the final forging. To get the optimal ring rolled blank, forged shape prediction using the finite element analysis method was applied. The forged dimensions produced by the new forging method were verified through the first article production.

An optimizing model to solve the nesting problem of rectangle pieces based on genetic algorithm

In the process of cement equipment manufacturing, the demand of rectangle pieces of steel structure is very large. The traditional manual nesting, which is simply cutting by hand-making according to the arrangement of the number and size, causes the low efficiency and material wasting. To solve the problem above, this paper proposes an optimizing model for nesting problem of rectangle pieces. Firstly, with the aim of the maximum utilization ratio of the sheet, the optimization mathematical model for nesting problem of rectangle pieces is established. The lowest horizontal line searching algorithm is described in detail. Secondly, the mathematical model is solved to get the optimal solution by the combination of genetic algorithm and the lowest horizontal line searching algorithm. In the solution process, this paper presents the methods of gene encoding and decoding, definition of fitness function, the design of genetic operators and the design of algorithm operating parameters. Finally, we use one sheet as an example to illustrate the proposed model and algorithm process. Experimental results have shown that the proposed approach is able to achieve rectangle pieces nesting with the maximum material utilization ratio.

Effect of dodecyl sulfate anions on the electrochemical performances of Zinc-Aluminum-hydrotalcite as anode material for Zinc/Nickel secondary batteries

Zn-Al-CO3 layer double hydroxides (LDHs) are synthesized by a simple hydrothermal method, followed by the anion-exchange processes to intercalate dodecyl sulfate (DS) anions into LDHs interlayer. The structures and morphologies of the as-prepared samples are characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results illustrate all samples have typical layer structure of LDHs, and the LDHs intercalated with dodecyl sulfate (LDH-DS) has better crystallization and smoother surface compares to conventional LDHs. Subsequently, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), Tafel and galvanostatic charge/discharge tests on LDH-DS electrode are performed. The results demonstrate that the exchanged sample has superior electrochemical performances in comparison with LDH-CO3, such as superior cycle stability, higher specific discharge capacity and utilization ratio of the active material. The specific discharge capacity of the LDH-DS electrode reaches 375mAhg−1 and exhibits excellent stability after 150 cycles.

Heat treated stone artifacts at Shuidonggou, Northwest China and their archaeological implications

Artifacts from the Shuidonggou (SDG) site complex in Ningxia province provide extensive information and insights regarding the activities of early modern humans in China. Based on a series of experiments and physical analyses, it appears that the stone artifacts from SDG Locality 2 and Locality 12 have undergone heat treatment that enhanced the utilization ratio and knapping properties of the lithic raw material from which they were made. In order to investigate the mechanisms involved, compression tests and XRD (X-ray Diffraction) examinations were conducted on lithic raw materials collected surround the SDG sites. The results indicate that the heated stones present lower compression strength and better ductility, and the raw material becomes more homogeneous as well. The process of crack propagation also becomes easier to control, thereby reducing knapping difficulties. The application of heat treatment technology at SDG reflects the production capacities and risk management strategies of the SDG inhabitants and provides evidence for the level of understanding associated with early modern human behavior. This discovery confirms the appearance of this technology in the East Asia around 32 ka BP (which lasts to 11 ka BP), providing new evidence for the spread and distribution of heat treatment technology.

Improvement in Cycle-Stability of Naphthoquinone-Based Rechargeable Organic Batteries By Polymerization

Using redox active organic materials, which contain no scarce metal resources, as a positive-electrode active material instead of conventionally used rare-metal oxides can be a solution to the resource problem of the current rechargeable lithium batteries. We have focused our attention on the redox active quinone-based materials which can lead to a high discharge capacity due to their multi-electron redox reactions and found that certain low-molecular-weight crystalline quinone derivatives exhibit high discharge capacities [1]. However, their discharge capacities tend to decrease upon cycling resulting from the loss of the active materials from the electrodes by the dissolution of the quinone molecules in the electrolyte solutions. To suppress the dissolution level of the quinone skeleton, we examined the polymerization of a quinone skeleton. In this paper, polymeric compounds were synthesized from 5,8-dihydroxy-1,4-naphthoquinone (DHNQ) (Fig. 1a) and their cycle-life performances were compared to that of the monomer.Polymers including the DHNQ skeleton (PDNQs) were synthesized by the condensation reaction between DHNQ and formaldehyde in an acidic media condition at the temperatures of 90, 100, and 150 oC. The obtained materials were characterized by the 1H-NMR, FT-IR spectroscopies, and the gel permeation chromatography (GPC). The positive-electrode was prepared by applying a composite sheet composed of the powder of the organic active material, acetylene black, and polytetrafluoroethylene in the weight ratio of 4:5:1 to a mesh-type aluminum current collector. The prepared positive-electrode was evaluated by making a coin-type half cell.The solubility of the quinone-based materials in the ordinary organic solvents was successfully decreased by polymerization. Fig. 1b compares the cycle-life performance of the prepared materials (PDNQs) to that of monomer (DHNQ). The electrodes using DHNQ showed a discharge capacity of 110 mAh g−1 in the first cycle. The obtained value is less than one fourth of the theoretical value based on the assumption of the four-electron redox reaction per molecule. The discharge capacity decreased rapidly upon cycling. On the other hand, the electrodes using PDNQs showed larger capacities than that of monomer at the first cycle. The obtained capacities are about 240-290 mAh g−1, and the utilization ratio of these polymeric materials were improved to 45 to 55 %. Furthermore, the stabilities were better than that of the monomer.There is a report about the charge/discharge behavior of a naphthoquinone polymer which was synthesized in a different way [2]. The previously reported polymer only showed a discharge capacity of about 60 mAh g−1 during cycling although its cycle-life was fair. On the other hand, our samples in this study showed relatively large capacities. We also performed another polymerization on the DHNQ moiety with sulfur. While the cycle-stability of the sulfur-containing polymer was also good, the capacity was not large enough during initial cycles. These results indicate that polymerization can be effective to improve the cycle-life performance of naphthoquinone-based active materials; however the synthesis method has a profound effect on their discharge capacities. Further optimization in the synthesis condition is considered to improve the discharge property.[1] M. Yao et al., J. Power Sources, 195 (2010) 8336.[2] A. Kassam et al., Electrochem. Solid-State Lett., 14, (2011) A22.

Electrochemical Performance of Quinone-Based Positive Electrodes for Lithium Secondary Battery

Quinone-based organic materials have reversal multielectron redox reactions. Cations in electrolytes are withdrawn or released by reduced quinone-based materials. Lithium ions being adopted, quinone-based materials are applied as an active material for lithium secondary battery. Due to their multielectron redox reactions, organic materials have an energy density even equal to inorganic materials. Inorganic materials must keep their crystal structure during cell operation, relating to reversibility of charge-discharge capacity, and the lithium conducting path in their crystal structure limit the mobility of lithium. On the other hand, organic materials do not need to keep their crystal structure owing to redox reaction within a molecule. Their electrochemical performances are not controlled by the lithium mobility in the lithium conducting path as in the case of inorganic materials. In addition, organic materials are relatively low-cost due to no metal elements and can be easily designed to fabricate their organic structure. However, their high solubility to electrolytes gives a large capacity loss, and their insulating properties lead directly to poor electron conduction during their redox reaction. These properties limit the rate performance and utilization ratio of organic materials. In this study, several organic materials, anthraquinone (AQ), 9,10-phenanthrenequinone (PQ), 1,10-phenanthroline-5,6-dione (N2PQ), and so on, were supported as much as possible on the surface of activated carbon (Maxsorb®) with nano-sized pores as a current collector for compensating their insulating properties. The organic materials-supported activated carbon was covered by a lithium conductive polymer (polyethyleneoxide, PEO) in order to restrict a dissolution of organic materials to electrolytes. The effect of organic structures on the electrochemical performance as positive electrodes was discussed. Discharge curves of positive electrodes using AQ, PQ, and N2PQ at 0.2 C show that two clear plateaus are detected for PQ (2.7 and 2.3 V) and N2PQ (2.9 and 2.5 V), respectively, and one plateau is detected for AQ (2.1 V). When two ketone groups in PQ and N2PQ are adjacent, radical anions reduced from neutral molecules through one electron redox reaction could exist stably by coordinating a lithium ion for a bridge formation. The coexistence regions of neutral molecules-radical anions and of radical anions-divalent anions result in two plateaus in the charge-discharge test of PQ and N2PQ. Redox potentials of PQ are higher than those of AQ because 1,2-diketone compound (PQ) receives a repulsion of two dipoles from each ketone, leading to a destabilization of neutral molecules and to easily reduction at the higher potential than 1,4-diketone compound (AQ). Heterocyclic compound (N2PQ) offers higher redox potential than PQ. In the field of complex chemistry, N2PQ behaves as a ligand for chelation. A resonance form of reduced N2PQ gives a negative charge to nitrogen atoms, and lithium ions are possibly withdrawn not only at oxygen atoms but also at nitrogen atoms. This coordinating ability of nitrogen atoms stabilizes the reduced form of N2PQ more than that of non-heterocyclic compound (PQ), reflecting higher redox potentials of N2PQ. Low polarization and high redox potentials in the charge-discharge test for N2PQ gives a high energy density of about 600 mWh g-1 when an electric double layer capacitance obtained from the activated carbon was removed. This value is comparable to inorganic active materials. A charge-discharge curve for N2PQ at 1.0 C shows two plateaus at 2.8 and 2.4 V. Discharge capacity in the 5th cycle at 0.2 and 1.0 C was 226 and 194 mAh g-1, respectively, and their utilization ratios of N2PQ (theoretical discharge capacity: 255 mAh g-1) were 89 and 76 %. The redox reaction of N2PQ through stable radical anion occurs smoothly to offer highly discharge capacity and rate performance.

Anode performances of mixed LiMn2O4 and carbon black toward lithium-ion battery

The mixed LiMn 2 O 4 and carbon black were served as anodes for lithium-ion batteries and the samples with high active material utilization ratio showed the highest capacity and cycling retention of 407.0 mAh/g after 50 charge/discharge cycles. The galvanostatic cycling and electrochemical impedance measurements were used to study their electrochemical performances. The commercial carbon black showed higher cycling retention, 162.0 mAh/g after 50 charge/discharge cycles. The present results confirmed that the capacity and cycling retention of LiMn 2 O 4 anodes can be improved by the increase of conductivity in lithium-ion batteries, which can increase the utilization ratio of active materials.

Die Design and Numerical Simulation for the Die Forging Forming of Shifting Fork

At present, the domestic most use the traditional machining methods of production, such as general milling, drill, ground, etc. But the traditional processing method is low material utilization ratio, time-consuming power consumption, and low production efficiency. as the same time the product quality is difficult to meet the requirement of high strength. In contrast, shifting fork forming die forging can improve labor productivity, and can obtain the ideal parts surface roughness and size accuracy. And with the forming of die forging the variable speed fork general rarely cutting processing, just in require special high points will has fine grinding. This design has completed the variable speed fork of die forging shape of mold design giving the design plan and design process. This topic is about the design of the numerical simulation, getting the expected of the press one.

Intrinsic Kinetics of Hydrorefining Catalyst in <i>Ex</i>-<i>Situ</i> Presulfurization

The intrinsic kinetics of hydrorefining catalyst in ex-situ presulfurization was investigated using a fixed-bed penetrating method. A mathematical model was built to express the intrinsic kinetics of presulfurization using an unreacted shrinking core model for catalyst grains and one-dimension unhomogeneous model for beds, and then the significance of the new model was tested. Results show that the presulfurization with hydrorefining catalyst was a nonstationary process, as the reaction rate changed with time, and this first-order reaction displayed high activation energy. In this dynamic mathematical model, a correction coefficient f0 was introduced into the common power-function-formed rate equation, which indicated the effects of solid diffusion on reaction. The model with high significance was able to improve the presulfurization rate and the raw material utilization ratio, thus providing theoretical guidance for achieving high presulfurization effects.

Chemical synthesis of PbO2 particles with multiple morphologies and phases and their electrochemical performance as the positive active material

In order to explore how to improve the electrochemical performance of the lead-acid battery positive active material, PbO2 particles with multiple morphologies and phases including urchin-like and ball-like β-PbO2 particles with size of 0.5–1 μm, flower-like α-PbO2 particles with size of 1–2 μm are chemically synthesized. These samples are composed of different smaller nanoparticles. The electrode made with urchin-like β-PbO2 and flower-like α-PbO2 in the ratio of 1:1 can deliver a discharge capacity of 183 mA h g−1 at 0.1 C after 100 cycles, and subsequent rate performance test shows that a discharge capacity of 97.2 mA h g−1 can be obtained even at 1 C. Moreover, this kind of electrode pretreated in 1 M H2SO4 solution displays improved stability of cycle, a capacity of 146.7 mA h g−1 can be obtained after 100 cycles, and its corresponding active material utilization ratio can reach 65%.

The Flow Field Distribution of Subsurface Flow Constructed Wetlands

this paper reviewed the progress of flow field distribution in subsurface flow constructed wetlands (SSF), generalized the theoretical basis for numerical simulation of flow field distribution and the application of computer software in subsurface flow constructed wetlands. At the same time, analysed the relationship of flow field distribution with the bed body of aspect ratio, substrate thickness, material properties of matrix and the way of filling, found that the appropriate aspect ratio, substrate thickness and scientific way of filling could improve the flow field distribution, which was an effective way to improve the utilization rate of substrate. In addition, summarized the plant roots system and microbe growth effect on the flow field distribution. Therefore, the flow field distribution was directly effected of utilization ratio of matrix material, and living environmental condition of microbe, thus the flow field distribution as a parameter for design would be a kind of scientific method. Finally, proposed the corresponding research methods, and discussed how to improve the flow field distribution uniform, for improving the design level of subsurface flow constructed wetlands.

Heat treatment and associated early modern human behaviors in the Late Paleolithic at the Shuidonggou site

Unearthed artifacts and cultural relics from the Shuidonggou site revealed extensive information and insights regarding the activities of early modern humans. A series of experimental research and physical analysis suggest that stone artifacts from Locality 2 and Locality 12 have undergone heat treatment. The utilization ratio and knapping properties of raw materials were consequently enhanced. Heat treatment technology reflects the production capacities and the survival strategies in the Upper Paleolithic period. This discovery indicates the earliest existence of this technology in the East Asia and thus confirms a wider geographic distribution of this technology which provides new perspectives and evidence for understanding the associated early modern human behaviors.