MEASUREMENT OF ANODIC OVERVOLTAGE BY AMODIFIED CURRENT INTERRUPTION METHOD IN CRYOLITE-ALUMINA MELTS

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Different surface modification methods and coating materials of zinc metal anode

Rechargeable aqueous Zn-ion batteries(AZIBs)are one of the most promising energy storage devices for large-scale energy storage owing to their high specific capacity,eco-friendliness,low cost and high safety.Nevertheless,zinc metal anodes suffer from severe dendrite growth and side reactions,resulting in the inferior electrochemical performance of AZIBs.To address these problems,surface modification of zinc metal anodes is a facile and effective method to regulate the interaction between the zinc anode and an electrolyte.In this review,the current challenges and strategies for zinc metal anodes are presented.Furthermore,recent advances in surface modification strategies to improve their electrochemical performance are concluded and discussed.Finally,challenges and prospects for future development of zinc metal anodes are proposed.We hope this review will be useful for designing and fabricating highperformance AZIBs and boosting their practical applications.

Temperature-dependent photoluminescence on organic inorganic metal halide perovskite CH_3NH_3Pb I_(3-)Cl_ prepared on ZnO/FTO substrates using a two-step method

Temperature-dependent photoluminescence characteristics of organic-inorganic halide perovskite CH3NH3Pb I3-xClx films prepared using a two-step method on ZnO/FTO substrates were investigated. Surface morphology and absorption characteristics of the films were also studied. Scanning electron microscopy revealed large crystals and substrate coverage. The orthorhombic-to-tetragonal phase transition temperature was-140 K. The films＇ exciton binding energy was 77.6 ± 10.9 meV and the energy of optical phonons was 38.8 ± 2.5 meV. These results suggest that perovskite CH3NH3Pb I（3-x）Clx films have excellent optoelectronic characteristics which further suggests their potential usage in perovskitebased optoelectronic devices.

Applying the Dynamic Two-Step Method to Forecast Remaining Oil Distribution of Lower Series ,Xiaermen Oilfield

The distribution of remaining oil is often described qualitatively. The remaining oil distributed in the whole reservoir is calculated according to the characteristics of the space distribution of the saturation of remaining oil. Logging data are required to accomplish this. However, many such projects cannot be completed. Since the old study of remaining oil distribution could not be quantified efficiently, the ＂dynamic two-step method＂ is presented. Firstly, the water cut of every flow unit in one well at one time is calculated according to the comprehensive water cut of a single well at one time. Secondly, the remaining oil saturation of the flow unit of the well at one time is calculated based on the water cut of the flow unit at a given time. The results show that ＂dynamic two-step method＂ has characteristics of simplicity and convenience, and is especially suitable for the study of remaining oil distribution at high water-cut stage. The distribution of remaining oil presented banding and potato form, remaining oil was relatively concentrated in faultage neighborhood and imperfect well netting position, and the net thickness of the place was great. This proposal can provide an effective way to forecast remaining oil distribution and enhance oil recovery, especially applied at the high water-cut stage.

Yttrium-Doped SnO_2 Prepared by Co-Precipitation Method for Lithium-Ion Battery Anodes

SnO2 doped with Y were prepared by co-precipitation method and tested in lithium-ion cells. The structure and morphology of the materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD patterns presented that the all the as-prepared materials had tetragonal rutile structure but a second phase (Y2O3) was observed when Y content reached 4%. TEM micrograph indicated that Y doped SnO2 had a small particle size ranging from 20 to 25 nm. The electrochemical properties for an anode active material in lithium-ion batteries were investigated at room temperature, including the observed capacity involved in the first-discharge and the reversible capacity values during subsequent charge-discharge cycles. The as-prepared Y-doped SnO2 exhibited promising electrochemical properties as anodes for lithium-ion batteries.

The convergence ball and error analysis of the two-step Secant method

Under the assumption that the nonlinear operator has Lipschitz continuous divided differences for the first order,we obtain an estimate of the radius of the convergence ball for the two-step secant method.Moreover,we also provide an error estimate that matches the convergence order of the two-step secant method.At last,we give an application of the proposed theorem.

High-stable and High-capacity Sn/SnO_(2)@C as Anode of Lithium-ion Batteries

We synthesized size-controllable nanoparticles with homogeneous distribution of carbon and Sn/SnO_(2)by a solvothermal method.The effects of different carbon content and hydrothermal time on the composition,morphology and electrochemical properties of the materials were investigated.Compared with bulk materials,nanoparticles materials not only have high specific surface area,but also can provide abundant reaction sites,thus enhancing the electrochemical activity of electrode materials.More importantly,the optimized microspheres Sn/8C-24 delivers a superior electrochemical performance,achieving a specific discharge capacity of 700.4 mAh·g^(-1)after 150 cycles at 0.5 A·g^(-1),and the Coulomb efficiency reaches 98.65%,which is promising for anode of LIBs.

A new two-step variational model for multiplicative noise removal with applications to texture images

Multiplicative noise removal problems have attracted much attention in recent years.Unlike additive noise,multiplicative noise destroys almost all information of the original image,especially for texture images.Motivated by the TV-Stokes model,we propose a new two-step variational model to denoise the texture images corrupted by multiplicative noise with a good geometry explanation in this paper.In the first step,we convert the multiplicative denoising problem into an additive one by the logarithm transform and propagate the isophote directions in the tangential field smoothing.Once the isophote directions are constructed,an image is restored to fit the constructed directions in the second step.The existence and uniqueness of the solution to the variational problems are proved.In these two steps,we use the gradient descent method and construct finite difference schemes to solve the problems.Especially,the augmented Lagrangian method and the fast Fourier transform are adopted to accelerate the calculation.Experimental results show that the proposed model can remove the multiplicative noise efficiently and protect the texture well.

Solution of Nonlinear Integro Differential Equations by Two-Step Adomian Decomposition Method (TSAM)

The Adomian decomposition method (ADM) can be used to solve a wide range of problems and usually gets the solution in a series form. In this paper, we propose two-step Adomian Decomposition Method (TSAM) for nonlinear integro-differential equations that will facilitate the calculations. In this modification, compared to the standard Adomian decomposition method, the size of calculations was reduced. This modification also avoids computing Adomian polynomials. Numerical results are given to show the efficiency and performance of this method.

Lattice Boltzmann simulation study of anode degradation in solid oxide fuel cells during the initial aging process

For present solid oxide fuel cells(SOFCs),rapid performance degradation is observed in the initial aging process,and the dis-cussion of the degradation mechanism necessitates quantitative analysis.Herein,focused ion beam-scanning electron microscopy was em-ployed to characterize and reconstruct the ceramic microstructures of SOFC anodes.The lattice Boltzmann method(LBM)simulation of multiphysical and electrochemical processes in the reconstructed models was performed.Two samples collected from industrial-size cells were characterized,including a reduced reference cell and a cell with an initial aging process.Statistical parameters of the reconstructed microstructures revealed a significant decrease in the active triple-phase boundary and Ni connectivity in the aged cell compared with the reference cell.The LBM simulation revealed that activity degradation is dominant compared with microstructural degradation during the initial aging process,and the electrochemical reactions spread to the support layer in the aged cell.The microstructural and activity de-gradations are attributed to Ni migration and coarsening.

Sol-gel synthesis of nanometer silicon/silicon suboxide/carbon anode material

A stacked Si/SiO_(x)/C composite anode material with carbon-coated structure was prepared by sol-gel method combined with carbothermal reduction using organic silicon.The results of X-ray diffractometry, scanning electron microscopy, and elemental analysis show that the Si/SiO_(x)/C material is a secondary particle with a porous micronanostructure, and the presence of nanometer silicon does not affect the carbothermal reduction and carbon coating.Electrochemical test results indicate that the specific capacity and first coulombic efficiency of SiO_(x)/C composite with nanometer silicon can be increased to 1 946.05 mAh/g and 76.49%,respectively.The reversible specific capacity of Si/SiO_(x)/C material blended with graphite is 749.69 mAh/g after 100 cycles at a current density of 0.1 C,and the capacity retention rate is up to 89.03%.Therefore, the composite has excellent electrochemical cycle stability.

Arrhenius relationship and two-step scheme in AF hyperdynamics simulation of diffusion of Mg/Zn interface

The accelerating factor （AF） method is a simple and appropriate way to investigate the atomic long-time deep diffusion at solid-solid interface. In the framework of AF hyperdynamics （HD） simulation, the relationship between the diffusion coefficient along the direction of z-axis which is normal to the Mg/Zn interface and temperature was investigated, and the AF＇s impact on the diffusion constant （D0） and activation energy （Q^＊） was studied. Then, two steps were taken to simulate the atomic diffusion process and the formation of new phases： one for acceleration and the other for equilibration. The results show that： the Arrhenius equation works well for the description of Dz with different accelerating factors; the AF has no effect on the diffusion constant Do in the case of no phase transition; and the relationship between Q＊ and Q conforms to Q^＊=Q/A. Then, the new Arrhenius equation for AFHD is successfully constructed as Dz=Doexp[-Q/（ART）]. Meanwhile, the authentic equilibrium conformations at any dynamic moment can only be reproduced by the equilibration simulation of the HD-simulated configurations. Key words： accelerating factor method; Arrhenius equation; two-steps scheme; Mg/Zn interface; hyperdynamic simulation

Fabrication and characterization of anodic oxide films on a Ti-10V-2Fe-3Al titanium alloy

Anodic oxide films of the titanium alloy Ti-10V-2Fe-3Al in ammonium tartrate electrolyte without hydrofluoric acid or fluoride were fabricated. The morphology, components, and microstructure of the films were characterized by scanning electron microscopy （SEM）, X-ray photoelectron spectroscopy （XPS）, X-ray diffraction （XRD）, and Raman spectroscopy. The results showed that the films were thick, uniform, and nontransparent. Such films exhibited sedimentary morphology, with a thickness of about 3 μm, and the pore diameters of the deposits ranged from several hundred nanometers to 1.5 μm. The films were mainly titanium dioxide. Some coke-like deposits, which may contain or be changed by OH, NH, C-C, C-O, and C=O groups, were doped in the films. The films were mainly amorphous with a small amount of anatase and rutile phase.

Fabrication and characterization of highly ordered Ni_(0.5)Zn_(0.5)Fe_2O_4 nanowire/tube arrays by sol-gel template method

Highly ordered nanowire/tube arrays of Ni0.5Zn0.5Fe2O4were fabricated by the sol-gel method in the pores of anodic alumina membrane （AAM）. Whether nanowires or nanotubes were fabricated depends on immersion time. The immersion time was 15- 40 s for nanotubes and over 60 s for nanowires. The topography and crystalline structure of the nanowire arrays were characterized by scanning electron microscopy （SEM）, transmission electron microscopy （TEM）, and X-ray diffraction （XRD）. It was found that the length and diameter of the Ni0.5Zn0.5Fe2O4 nanowires are related to the thickness of the AAM and the diameter of the pores. The results indicated that the Ni0.5Zn0.5Fe2O4 nanowires are uniform and parallel to each other.

Interconnected sandwich structure carbon/Si-SiO_2/carbon nanospheres composite as high performance anode material for lithium-ion batteries

In the present work,an interconnected sandwich carbon/Si-SiO2/carbon nanospheres composite was prepared by template method and carbon thermal vapor deposition（TVD）.The carbon conductive layer can not only efficiently improve the electronic conductivity of Si-based anode,but also play a key role in alleviating the negative effect from huge volume expansion over discharge/charge of Si-based anode.The resulting material delivered a reversible capacity of 1094 mAh/g,and exhibited excellent cycling stability.It kept a reversible capacity of 1050 mAh/g over 200 cycles with a capacity retention of 96%.

A Novel Method of Fabricating a Well-Faceted Large-Crystal Diamond Through MPCVD

A novel method was developed to deposit a large crystal diamond with good facets up to 1000 μm on a tungsten substrate using a microwave plasma enhanced chemical vapor deposition （MPCVD）. This method consists of two steps, namely single-crystal nucleation and growth. Prior to the fabrication of the well-faceted, large crystal diamond, an investigation was made into the nucleation and growth of the diamond which were affected by the O2 concentration and substrate temperature. Deposited diamond crystals were characterized by scanning electron microscopy and micro-Raman spectroscopy. The results showed that the conditions of single-crystal nucleation were appropriate when the ratio of H2/CH4/O2 was about 200/7.0/2.0, while the sub- strate temperature Ts of 1000℃ to 1050℃ was the appropriate range for single-crystal diamond growth. Under the optimum parameters, a well-faeeted large crystal diamond was obtained.

The Research on Biogas Power Generation by Two Step Method

The paper aims to demonstrate the system of SANYI biogas power generation by two-step method which can produce methane and generate electricity effectively and stably.So it can be stable synchronization meshwork energy source establishment and provide references to develop an effective and stable project of producing methane and generating electricity.

Nitrogen-doped lignin based carbon microspheres as anode material for high performance sodium ion batteries

Nitrogen-doped lignin-based carbon microspheres are synthesized using 3-aminophenol as a nitrogen source by the hydrothermal method.The structural change and the effect on the electrochemical properties are systematically investigated. Nitrogen-doped lignin-based carbon microspheres represent well-developed spherical morphology with many active sites, ultramicroporous(< 0.7 nm) structure, and large interlayer spacing. Consistent with the obtained physical structures and properties, the nitrogen-doped carbon microspheres exhibit fast sodium ion adsorption/intercalation kinetic process and excellent electrochemical performance. For example, a reversible specific capacity of 374 m Ah g^(-1) at 25 m A g^(-1) with high initial coulombic efficiency of 85% and high capacitance retention of 90% after 300 cycles at 100 m A g^(-1) and stable charge/discharge behavior at different current density is obtained. The additional defects and abundant ultramicroporous structure can enhance sloping capacity, and large interlayer spacing is considered to be the reason for improving plateau capacity.

Graphite Anode for Potassium Ion Batteries: Current Status and Perspective

With the increased demand from the storage of renewable energy sources,some safe and inexpensive energy storage technologies instead of Li-ion batteries become urgently needed.Therefore,K-ion batteries(KIBs)have attracted much attention and evolved significant development because of the low price,safety,and similar property compared with Li-ion batteries.Due to the high reversibility,stability,and low potential plateau,graphite becomes a current research focus and is regarded as one of the most promising KIB’s anode materials.In this review,we mainly discuss the electrochemical reaction mechanism of graphite during potassiation-depotassiation process and analyze the effects of electrode/electrolyte interface on graphite for Kion storage.Besides,we summarize several kinds of methods to improve the performance of graphite for KIBs,including the design of graphite structure,selection of appropriate binder,solvent chemistry,and salt chemistry.Meanwhile,a concept of“relative energy density”is raised,which can be more accurate to evaluate the genuine electrochemical performance of graphite anode involving the specific capacity and potential.In addition,we also summarize the considerable challenges to current graphite anode in KIBs and we believe our work will offer alterative solutions to further explore high-performance graphite anode of K-ion storage.

Electroanalytical Study of Electrode Processes on Carbon Anode in Lithium Fluoride and Neodymium Fluoride Melt

The anode processes of carbon electrode in LiF-70%NdF3 melt were studied by electroanalytical techniques, including cyclic voltammetry(CV) and chronoamperometry(CA). Anode gases were analyzed by gas chromatography(GC) on-line during controlled-potential electrolysis. Two anode peaks were observed. The first process starting at 2.0 V vs Li+/Li was corresponded to the discharge of residual oxide ions, with the generation of CO and CO2. The discharge of fluoride ions occurred at the potentials higher than 4.3 V vs Li+/Li, with the generation of a small amount of CF4 and C2F6, accompanied by a sudden drop in current, marking the onset of the anode effect. The second process occurred when the potential exceeded 5.5 V vs Li+/Li, with the generation of a large amount of CF4 and C2F6. When the temperature was changed from 1173 to 1273 K, the current of the second process decreased, leading to a stable anode effect.