bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling of the Thermal Behaviors of an Ultracapacitor and Comparison with Measurement Data
Authors: Koo Boram , Shin Chee Burm , Lee Ha-Young , Choi Jongrak 
Published: February 2020

Ultracapacitors (UCs), known by different names such as supercapacitors, electrochemical double-layer capacitors, double-layer capacitors or electrochemical capacitors, have the potential to meet the high pulse power capability of the energy-storage systems for automotive applications. The primary advantages of UCs are higher power density and longer shelf and cycle life as compared to those of batteries. In the high pulse power operations for automotive applications, a large amount of heat is produced inside a UC cell. Because the lifetime and performance of a UC depend strongly on temperature, it is important to predict accurately the thermal behaviors of a UC for the efficient and reliable systems integration from an application perspective.
In this work, a three-dimensional thermal model is presented to predict the thermal behaviors of the UC. Both of the irreversible and reversible heat generations inside the UC cell are considered. The effective density and specific heat capacity of the various compartments of the cell are estimated based on the mass fractions of the components of each cell compartment. The effective thermal conductivities of the various compartments of the cell are estimated based on the equivalent networks of parallel and series thermal resistances of the cell components. The validation of the three-dimensional thermal model is provided through the comparison of the modeling results with the experimental IR image at various charge/discharge currents.
Transition Metals Ion Behavior of Cathode Materials for Li Ion Battery By Electron Beam Irradiation in Scanning Transmission Electron Microscopy
Authors: Shim Jae-Hyun , Kim Young-Min 
Published: February 2020

Investigating the structural properties of Li-ion batteries (LIBs) and, if possible, determining the overall structure is important in understanding the physical and chemical properties. Understanding the structural properties and the electrochemical properties of the arranged atoms of cathode materials is therefore essential for new battery material design and system optimization. Particularly, cathode materials such as LiNixMnyCo1-x-yO2 (NMC), lithium-rich Li(LiyNix-yMnxCo1-2x)O2, lithium-rich / manganese-rich xLi2MnO3 (1-x)LiMO2 are analyzed by the scanning transmission electron microscopy (STEM) techniques to identify structural characteristics, leading to the conversion of the layer structure to the spinel and/or salt structure, leading to increased impedance, voltage reduction and capacity of the LIBs.
The atomic behavior of Li ion in the cathode materials that determines LiBs performance is hardly characterized by transmission electron microscopy (TEM) owing to its weak electron-scattering power. In this sense, annular bright-field (ABF) STEM, in which the contrast has a low scaling rate with the atomic number, has been proven to be a robust technique for simultaneous imaging of light and heavy elements. However, it is very important to understand the damage mechanism of cathode materials by electron-beam irradiation in STEM and to develop this technique. In this study, we investigated the effect of electron-beam irradiation damage on the surface reaction layer and LiNi0.6Co0.2Mn0.2O2 material during STEM data acquisition. This electron-beam irradiation damage process is similar to the lattice reconstruction and chemical evolution caused by the charge-discharge cycle. Furthermore, based on the phase transition phenomenon by the electron-beam irradiation, it is examined whether the electron beam irradiation damage in the lattice structure substituted by Al and Ti affects the phase transition phenomenon.
Structural Characterization of Anodic Porous Alumina Formed By Galvanostatic Anodizing in Etidronic Acid
Authors: Iwai Mana , Kikuchi Tatsuya , Suzuki Ryosuke O. , Natsui Shungo 
Published: February 2020

Anodizing aluminum in etidronic acid (1-hydroxyethane-1,1-diphosphonic acid) causes the formation of porous alumina at higher voltage more than 200 V. Highly ordered porous alumina with a large-scale cell can be easily fabricated via two-step constant voltage anodizing in etidronic acid. However, extremely little has been reported on the growth behavior during galvanostatic anodizing in etidronic acid and its structural characterization. In the present investigation, we demonstrate the details of the anodizing behaviors and nanostructures of the porous alumina formed via galvanostatic anodizing in etidronic acid under various operating conditions.
High-purity aluminum plates were electrochemically polished, and then were anodized at a constant current density of 0.005-500 Am-2 in 0.03-3 M etidronic acid solutions (273-333 K). After anodizing, the specimens were immersed in a 0.20 M CrO3/0.51 M H3PO4 solution (353 K) to dissolve the porous alumina, and the aluminum dimple array was exposed to the surface. The surface and cross-section of the anodized specimens were examined by field-emission scanning electron microscopy (FE-SEM). The cell size (interpore distance) of the porous alumina was calculated using image analysis software.
As the electropolished aluminum specimens were anodized galvanostatically under various conditions, the voltage linearly increased, gradually decreased, and then reached plateau value (U
p). However, excess current density led to a burning phenomenon and the formation of non-uniform porous alumina. Figure 1 shows the changes in the plateau voltage, U
p, and the current density, i
a, during anodizing in a 0.3 M etidronic acid solution. The plateau voltage greatly increased with the current density at each temperature, and various porous alumina films were successfully fabricated by anodizing at a wide voltage range measuring 7-218 V. Figure 2 shows the relationship between the cell size, D
c and the anodizing voltage, U
a. The cell size linearly increased with the anodizing voltage at each solution temperature and current density. A linear proportional constant of 2.5 nmV-1 was obtained, which is similar to the self-ordering condition via constant voltage anodizing.

Figure 1
Alkaline Corrosion-Resistant Anodic Aluminum Oxide Formed By Etidronic Acid Anodizing
Authors: Suzuki Yusuke , Kawahara Kai , Kikuchi Tatsuya , Suzuki Ryosuke O. , Natsui Shungo 
Published: February 2020

A newly discovered electrolyte for anodizing aluminum, etidronic acid (CH3C(OH)[PO(OH)2]2), operates at high voltages of more than 200 V, and ordered porous alumina measuring 400-670 nm in cell diameter (interpore distance) can be fabricated via constant voltage anodizing. Because such porous alumina film formed at high voltages possesses a thick barrier layer, etidronic acid anodizing may be useful for corrosion protection of aluminum. Here, we describe the alkaline corrosion-resistant porous alumina formed by high voltage anodizing in an etidronic acid solution, and its hydration behavior in boiling water was investigated.
Highly pure aluminum plates (99.999 wt%) were anodized in 0.3 M sulfuric acid, 0.3 M oxalic acid, 0.3 M citric acid, and 0.3 M etidronic acid solutions (293 K) at a constant current density of 30 Am-2 or a constant voltage of 250 V. The anodized specimens were immersed in a 2.5 M NaOH solution (293 K). The nanostructural changes were examined by electrochemical impedance spectroscopy (EIS). The anodized specimens were immersed in boiling water to seal the pores in the porous alumina film. The surface and cross-section of the specimens were characterized by field-emission scanning electron microscopy (FE-SEM)
The plateau voltages during anodizing aluminum at a constant current density of 30 Am-2 in sulfuric and etidronic acid solutions exhibited approximately 16 V and 197 V, respectively. As the specimen anodized in sulfuric acid was immersed in a 2.5 M sodium hydroxide solution, H2 gas evolution was observed from the surface at the beginning of immersion, and the amount increased with the immersion time. In contrast, the specimen anodized in etidronic acid did not result in hydrogen gas evolution during immersion until 8 min. Here, the capacitance (Cb
) is inversely proportional to the thickness of the barrier layer. Figure 1 shows the changes in the reciprocal Cb
with the immersion time, ti
. Complete dissolution of porous alumina formed in etidronic acid takes 15 times longer than dissolution of the alumina formed by sulfuric acid anodizing due to the formation of a thick barrier layer.
As the porous alumina formed by etidronic acid anodizing is immersed in boiling water, plate-like hydroxides were formed at the bottom of the pores in the initial immersion stage. The thickness of the hydroxide layer increased with the immersion time, and the nanopores are completely sealed by long-term immersion.

Figure 1
(Invited) Stoner Ferromagnetism in Two-Dimensional Materials
Authors: Houssa Michel , Meng Ruishen , Iordanidou Konstantina , Pourtois Geoffrey , Afanas'ev Valery V. , Stesmans Andre 
Published: February 2020

Two dimensional (2D) materials are currently attracting considerable interest due to their promising applications in future nanoelectronic devices. Ferromagnetic 2D materials are also gaining attention, for their possible use in novel spintronic devices [1]. Hole-doping in monolayers of GaX, InX (X=S or Se) and SnO has been recently predicted to induce a paramagnetic to ferromagnetic phase transition in these 2D materials, for typical hole densities in the range of 1013-1014/cm2 [2-6]. Ferromagnetism in these materials arises from an exchange splitting of electronic states at the top of the valence band, where the density of states exhibits a sharp van Hove singularity, resulting in a so-called Stoner (magnetic) instability; this behavior is typical of materials with “Mexican-hat” energy band edges, as predicted in GaX, InX and SnO monolayers.
In this talk, the results from first-principles simulations of the hole-doping induced Stoner ferromagnetism in various 2D materials will be discussed. The possibility to dope these materials with holes, either by intrinsic or extrinsic defects, will be considered. The possible Stoner ferromagnetism in other 2D metal oxides will also be highlighted.
[1] W. Han, APL Mater. 4, 032401 (2016).
[2] T. Cao et al., Phys. Rev. Lett. 114, 236602 (2015).
[3] L. Seixas et al., Phys. Rev. Lett. 116, 206803 (2016).
[4] M. Houssa et al., ECS Trans. 80, 339 (2017).
[5] M. Houssa et al., AIP Adv. 8, 055010 (2018).
[6] K. Iordanidou et al., ACS Appl. Nano Mater. 1, 6656 (2018).
The Metal Gate Cut Process(Part I): Plasma Assistant CD Shrinkage
Authors: Ji Shi-liang , Liu Shaoxiong , Zhang Haiyang 
Published: February 2020

The technology of FinFET has led to the continuity of device scaling and enabled the prolongation of Moore’s Law towards the 7 nm and beyond nodes. The gate cut last has been widely adopted since it can provide better SiP/SiGe growth environment, hence yielding the better electrical performance. However, this approach requires more complex process engineering at 3D structure. Both perfect physical structure and good electronic performance are challenging for gate cut last process.
As is well known, the metal gate cut process is the inevitable choice of 5nm FinFET and GAA FinFET, which directly determines the performance of FinFET. At present, the metal gate cut process has suffer the following difficulties: the Critical Dimension of the metal gate is only about ten nanometers, the height is about one hundred nanometers, and the aspect ratio has exceeded the limit of the most advanced etching tool; the metal gate complex composition, including more than 10 kinds of metal and insulation materials; the cut CD is very small, but the profile requirement is very challenging, all the metal layers are vertical, and the same CD is maintained from top to bottom. The bigger challenge is that the line end of metal gate cut is very close to germanium silicon or phosphor silicon. On the other hand, the metal's easy collection of charge and easy conduction will greatly increase the plasma induce damage risk, which needs to be controlled by properly selecting etching conditions.
We will start a series of studies on the above issues and discuss the development direction and research ideas in each aspect. This manuscript will focus on how to use plasma etching technology to shrink CD in the soft mask etching process so as to break through the exposure limit of the immersion lithography. In general, immersion lithography with negative photoresist can not complete less than 40 nm CD, but gate cut, especially metal gate cut CD need as small as 20 nm. This puts forward very high requirements for soft mask etching. On the one hand, etch stop or defect cannot be caused with the large CD shrinkage; on the other hand, the CD should meet the design requirements and the patterning should be complete. We use the CxHyFz as etching gas with the advanced coupled plasma etching tool.We found the high/low bias pulsing scheme can reach balance on all sides, as the CD shrinkage, defect control, pattern transfer, line width roughness, the optimum process window.
Application of Broadband Microwave Metrology to Emerging Integrated Circuit Device Reliability Analyses
Authors: Obeng Yaw S. , Amoah Papa K. 
Published: February 2020

Metrology is needed to characterize structure and composition in emerging integrated circuits at the nano-scale. Interconnect technology has been identified as the largest single factor limiting both performance, power, and reliability of emerging devices. The artifacts of interest may be exposed or embedded and may occur at any stage of device fabrication. We are particularly interested in metrology for the accurate understanding and quantification of the reliability issues associated with interconnect metallization in emerging nanoelectronic devices. In this regard, we have developed a suite of broadband microwave (RF)-based metrology techniques to non-destructively identify, measure, and characterize performance-limiting defects in emerging nanoelectronic devices. These RF based metrology tools offer several advantages over the traditional techniques and are uniquely suitable for studying the kinds of problems we are interested in. For example, the traditional low-frequency resistance (RDC) measurements, commonly used for electromigration, are based on changes in the resistance of conductive pathways. So long as there are contiguous electrical paths, the devices under test will not fail the RDC test. In contrast, changes in RF insertion losses offer early prognostics.
In this talk, we describe the application of a suite of broadband microwave-based techniques to the interconnect reliability assessment of integrated circuits. We discuss how microwave propagation characteristics have been used to study the impact of thermal aging on phenomena such as stress-induced failures, electromigration, and corrosion of the interconnects in 3D-ICs. We will also compare the mechanistic insights obtained from the traditional resistance increases in low-frequency direct current to those from high-frequency measurements.
Electrodeposition and Characterization of Ultra-Thin Films As Model Systems for Electrocatalysis
Authors: Berretti Enrico , Giaccherini Andrea , Di Benedetto Francesco , Montegrossi Giordano , Lepore Giovanni Orazio , Puri Alessandro , D'acapito Francesco , Dell'Aquila Vincenzo , Lavacchi Alessandro 
Published: February 2020

Platinum is nowadays considered the best catalyst for many anodic and cathodic reactions in fuel cells. However, its low abundance poses a limit for its usage in such devices. In recent years, much effort has been done to substitute this metal whit more abundant ones, in particular concerning the alcohol electrooxidation process in direct alkaline alcohol fuel cells (DAFC).In this respect, palladium (which shares with platinum a similar catalytic activity towards alcohol electrooxidation) may represent a viable substitute for the anodic compartment in DAFC, but its main limit resides in the deactivation process (oxidation of the metal) that occurs during the cell duty cycle.
Aiming to study this phenomenon, different catalytically active bimetallic Au-Pd electrodes were prepared
by combined Under-Potential Deposition (UPD) of copper and Surface Limited Redox Replacement (SLRR) with Pd, exploiting homemade Au (111) polycrystalline surfaces. This catalytic ultra-thin layers (with different Pd coverages above Au) proved to be robust and reproducible, both morphologically and electrochemically. Moreover, this method enabled the preparation of large, flat and homogeneous surfaces, enabling their use as model surfaces in synchrotron light experiments (performed at the BM-08 line of the ESRF in Grenoble), where a blend between the Grazing Incidence X-ray Absorption Spectroscopy (GIXAS) and the Fixed Energy X-Ray Absorption Spectroscopy (FEXRAV) was exploited. This novel experimental set-up, a grazing Incidence FEXRAV technique (GI-FEXRAV), allowed to follow in operando changes in the speciation of the Pd during voltammetric scans, and thus to disclose its deactivation/dissolution in systems with a very low catalytical load. Finally, with this novel set-up we just sampled the topmost catalytic layer, thus greatly enhancing the capability to study small modifications of the surface.
Enhancing the Hydrogen Evolution Reaction Using Oxide Nanoparticles: Electrodeposited Ni-W-TiO2
Authors: Zhang Yujia , Podlaha Elizabeth J. 
Published: February 2020

Electrodeposited tungsten alloys containing nickel are well-known electrocatalysts for the hydrogen evolution reaction (HER), with the added benefit of being corrosion resistant.1 The addition of nano-scale, solid oxide particles in the deposit could serve as a potential strategy to further improve the electrocatalytic properties. In the present study, Ni-W-TiO2 composites were fabricated by electrodeposition with different loadings of TiO2 nanoparticles in the electrolyte. The influence of (1) the titania particles in the electrodeposition electrolyte on the hydrogen evolution side reaction and the metal partial current densities are assessed, and (2) the embedded titania particles in Ni-W on the HER kinetics in an alkaline electrolyte are also examined.

Electrodeposition

A citrate-boric acid electrolyte was used to deposit Ni-W alloys and Ni-W-TiO2 composites onto rotating cylinder electrodes, at a pH of 8. The partial current density ratio of Ni/W was affected by the amount of particles in the electrolyte, explained, in part, by differences in adsorption that governs the metal ion induced codeposition mechanism. The hydrogen evolution side reaction was enhanced during deposition when particles were present.

HER Electrocatalysis

HER kinetic parameters of the electrodeposited Ni-W-TiO2 composites and their alloy counterparts, were examined in 1 M NaOH. The embedded TiO2 improved the HER Tafel slope of the electrocatalyst. To compare the overpotential and the exchange current density the electroactive surface area was characterized using a ferricyanide electrolyte with cyclic voltammetry. Under comparable surface areas and metal composition ratio, there was an improvement in lowering the overpotential with the composites but there was no change in the exchange current density. The addition of TiO2 to a Ni-W matrix to enhance HER serves as a model system that can be adapted to other alloy electrocatalysts.
In both electrodeposition and electrocatalysis, the TiO2 is suspected of altering the adsorption of reaction intermediates.

Reference

Tsyntsaru, H. Cesiulis, M. Donten, J. Sorte, E. Pellicer, and E. J. Podlaha-Murphy, Surface Engineering and Applied Electrochemistry, 48 491 (2012).
(Invited) Electrodeposition As a Versatile Method to Prepare Materials for the Storage and Conversion of Sustainable Energy
Authors: Ispas Adriana , Borisenko Natalia , Wang Dong , Fritz Mathias , Kurniawan Mario , Ivanov Svetlozar , Bund Andreas 
Published: February 2020

Sustainable energy carriers such as sun light, wind or biomass will play a crucial role in our future. After converting the energy, one should be able to store it and transport it to places where it is needed most. Therefore, the research on materials for storage systems, such as batteries, supercapacitors and fuel cells is an important aspect. Electrodeposition is a powerful technique for the preparation of such materials.
As industry strives to produce smaller portable devices, one needs also smaller and lighter batteries with a high storage capacity per gram of active material. The commercial graphite anodes are limited to ca. 370 mAh/g, but silicon and C-Si composites have a theoretical storage capacity beyond 1000 mAh/g. Thus, nanostructured Si, such as nanoporous Si layers, ordered arrays of Si (porous) nanopillars produced by using a combination of nanoimprint lithography and metal-assisted chemical etching or silicon thin films deposited from ionic liquids could be used as high-capacity anodes in Li-ions batteries.
Another interesting semiconductor material besides Si is Cu2O. Photo-cathodes from Cu2O can be used to produce hydrogen as a chemical fuel by utilizing direct solar energy and its narrow bandgap of 2.0-2.2 eV that can lead to the theoretical value of solar-to-hydrogen efficiency of 18 %. One can fabricate Cu/Cu2O porous electrodes using the hydrogen bubbles as a dynamic and effective template by electrochemical deposition. These foam electrodes can then be used as photocathodes for water electrolysis under visible light irradiation.
This contribution will discuss recent results from the authors’ labs on developing new anode materials for Li-ion batteries (Si based), new electrodes for electrochemical water splitting (Cu2O based) and for electrocatalysis. Further, approaches using light induced plating for electrical front side contacts of solar cells will be presented.
Investigation of the Electrochemical Kinetics of Aluminum Deposition from Ionic Liquids
Authors: Böttcher René , Ispas Adriana , Bund Andreas 
Published: February 2020

The electrochemical deposition of a number of reactive metals such as Al, Ta and Nb from ionic liquids (ILs) generated high interest during the last decades. Their deposition from aqueous solutions is not possible since these metals have a rather negative Nernst potential. Non-aqueous media have a broader electrochemical window (> 3 V) and offer new possibilities for industrial applications by electrochemical plating of highly reactive metals.
Due to its excellent properties such as high conductivity and the formation of a dense oxide film, the possible applications of aluminum range from electronics and optics all the way to coatings for corrosion protection and decorative purposes. The negative standard potential of aluminum (-1.66 V vs. SHE) led to the development of non-aqueous electrolytes used in industrial processes (e.g. SIGAL process), which are often based on highly flammable and/or volatile chemicals, leading to high costs and risks for the operator. ILs are non-flammable, have a high solubility for metal salts and there is no hydrogen embrittlement due to their aprotic nature. Furthermore, continuously decreasing prices for ILs make them more interesting for industrial processes.
Aluminum was one of the first metals electrochemically deposited from ILs. There are a lot of reports about the pure metal and its alloys. However, there are some basic knowledge gaps about the electrochemical kinetics of the aluminum deposition from ILs.
This paper will discuss recent results from the authors’ lab on the electrochemical kinetics of the deposition of aluminium from 1-ethyl-3-methyl-imidazolium based ILs. A number of high and low amplitude step experiments completed by cyclic voltammetry and conductivity measurements were employed to shed light on the diffusion, nucleation and charge transfer mechanism of the aluminium deposition.