bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Effect of Cr Concentration on Dissolution of (Mn,Cr)S Inclusions in Stainless Steel
Authors: Nishimoto Masashi , Muto Izumi , Sugawara Yu , Hara Nobuyoshi
Published: December 2020

The pit initiation sites for commercial stainless steels have been attributed to sulfide inclusions such as MnS. The chemical composition of the inclusions affects the pitting corrosion resistance of stainless steels. In general, MnS inclusions in stainless steels contain a small amount of Cr, and thus they are accurately written as (Mn,Cr)S inclusions. It has been reported that Cr in (Mn,Cr)S inclusions have an inhibitory effect on the dissolution of the inclusions. However, the extent to which the Cr concentration in the inclusions prevents the dissolution of the inclusions remains unclear. In this study, spark plasma sintering was used in the facile fabrication of stainless steel specimens containing artificial (Mn,Cr)S inclusions with different Cr concentrations.1 A microelectrochemical technique was applied to elucidate the effect of Cr concentration on the dissolution of the inclusions in stainless steel.

Type 304 stainless steel powders were mixed with either MnS or Cr2S3 powders to prepare sintered specimens containing 0.06 mass% S. The mixed powders were loaded into a cylindrical graphite die and subsequently compressed into a pellet. The pressed compact was sintered under vacuum conditions and uniaxial pressure in a spark plasma sintering system. The sintered specimens were ground with SiC papers and then polished with diamond pastes. Potentiodynamic polarization was conducted in naturally aerated 0.1 M NaCl (pH 5.5) at 298 K. The specimen surface was masked to make an electrode area of approximately 100 µm × 100 µm containing a single artificial inclusion. All the potentials reported in this study refer to the Ag/AgCl (3.33 M KCl) electrode (0.206 V vs. standard hydrogen electrode at 298 K). During polarization, the electrode area was observed using an in situ real-time optical microscopy system.2

The anodic polarization curves were measured to analyze the dissolution and pit initiation behavior of the artificial (Mn,Cr)S inclusions. The onset potential of inclusion dissolution and the pitting potential increased with increasing Cr concentration in the inclusions. The onset potential of inclusion dissolution reached approximately 0.7 V when the Cr/(Mn+Cr) atomic ratio in the inclusion was more than 0.5. This potential is almost the same as the transpassive region of Type 304 stainless steel. There was not much difference even if the Cr/(Mn+Cr) ratio of the inclusions was higher than 0.5. We concluded that the inhibitory effect of Cr on the dissolution of (Mn,Cr)S inclusions is most effective when the Cr/(Mn+Cr) ratio is 0.5.

References:

M. Nishimoto, I. Muto, Y. Sugawara, and N. Hara, ISIJ Int., 60, 196-198 (2020).

A. Chiba, I. Muto, Y. Sugawara, and N. Hara, J. Electrochem. Soc., 159, C341-C350 (2012).
(Invited) Rapid Photo-Charge Mapping of Stainless-Steel Under the Hydrogen Permeation
Authors: Azumi Kazuhisa , Masaki Hiroto , Baba Kazuhiko
Published: December 2020

Photocurrent techniques have been applied to analyze the properties of passive films on metals and their corrosion phenomena. Photocurrent mapping is also used to evaluate the inhomogeneity of, for example, non-uniform corrosion behavior by using a lock-in amplifier to detect a weak photocurrent signal combined with a laser light scanning. This method is, however, takes a long time to acquire a scanning image due to a rather slow time-constant of the lock-in amplifier measurement. In this work, a photo-charge mapping method is developed in which an intense UV laser pulse light (405 nm, 0.5 W in the present study) is focused on the specimen surface and a photo-charge evolved by a single laser pulse is evaluated by integrating the photocurrent using an electronic integrator, as shown in Fig. 1. An intense laser pulse provides a large photocurrent in some condition sufficiently for a single photocurrent pulse analysis. Fast scanning of the laser light is also achieved by using a galvano-scanner. Currently, a time required for one image acquisition is a few minutes which is limited due to the software execution time.

In this work, the spatial distribution of hydrogen permeation in a stainless-steel sheet (SUS304, 0.1 mm in thickness) placed in a Devanathan cell was traced under the tensile stress test. Hydrogen was introduced from the backside of the sheet by using the galvanostatic cathodic polarization at –1mA cm–2, and penetrated hydrogen to the front side was oxidized under the anodic polarization at +0.8 V vs. Ag-AgCl R.E. The passive film was pre-formed before the hydrogen penetration. Absorption of hydrogen into stainless steel caused a drastic increase of photocurrent on the n-type semiconductor passive film due to the photo-assisted oxidation of permeated hydrogen atom via a stainless-steel sheet, i.e., hydrogen atoms can be effectively oxidized by the holes generated by UV irradiation in the passive film. In the photo-charge image shown in Fig. 1, left half of the observed area (4mm x 4 mm, 40 x 40 pixel) was penetrated by hydrogen from the backside where the increase of photo-charge was observed.

The Devanathan cell was combined with a tensile tester, and a photo-charge map was traced during the hydrogen loading under the loading condition until the notched sample was cleaved. The photo-charge intensity increased around the notch before cleavage, probably due to an increase of hydrogen concentration penetrated or thickening of the passive film.

Figure 1
(Invited) Surface Analysis of Corrosion Products Built up at Interfaces of Different Nuclear Waste Forms in Near-Field Environment
Authors: Guo Xiaolei , Gin Stephane , Lei Penghui , Yao Tiankai , Liu Hongshen , Schreiber Daniel , Ngo Dien , Viswanathan Gopal B , Li Tianshu , Kim Seong , Vienna John D. , Ryan Joseph V. , Du Jincheng , Lian Jie , Frankel Gerald S.
Published: December 2020

In this study, we applied a series of surface analysis techniques to explore the structure and chemistry of the corrosion products built up at the interface of different materials, which is relevant to the permanent disposal of world-wide high-level nuclear waste. Metallic alloys, amorphous glass, and crystalline ceramics are typical candidate nuclear waste forms planned for immobilizing and isolating the dangerous radionuclides enriched in the waste. The near-field corrosion interactions between these dissimilar materials are the focus of this study. The experiments were performed by corroding metallic alloys in intimate proximity to glass or ceramics in Cl--containing solutions at 90 oC. The exposed materials were subsequently subjected to comprehensive surface characterization using X-ray photoelectron spectroscopy, scanning transmission electron microscopy, energy dispersive spectroscopy, time-of-flight secondary ion mass spectrometry, and Raman/infrared spectroscopy analysis. The systematic study revealed localized damage on the alloy surface due to crevice corrosion. Interestingly, localized corrosion was also identified on the surface of some glasses and ceramics that were present nearby, while an inhibition effect was observed in other systems. These interactions were found to strongly depend on the type of materials and environment, which led to different corrosion phenomena.
(Invited) Radiolysis and Corrosion of Stainless Steel in High Temperature Water Environment
Authors: Feron Damien , Wang Mi , Corbel Catherine , Perrin Stephane
Published: December 2020

This paper focus on the corrosion behaviour of austenitic 316L stainless steel in PWR primary water under the influence of radiolysis, including experimental devices and main obtained results.

After a short overview of the literature in the field, the approach is described with the use of a high energy proton beam to control the production of radiolytic species at the interface between stainless steel (316L type) and PWR water solution in a high temperature and high pressure electrochemical cell working up to 300°C and 100 bar.

The corrosion potential of stainless steel was enhanced by the radiolysis causing by high energy proton beam. A high similarity of electrochemical behaviour was also observed under electron beam. The electrochemical oxidative response of the 316L/PWR solution interface under radiolysis is related to the surface characterization analysis (SEM, XPS, Raman spectroscopy, NRA...) on the oxide layers of 316L which are formed under or without irradiation. The radiolysis effect on the oxide film includes micron scale cavities which were observed in a highly irradiated oxide film. The observation of a-Fe2O3 hematite on the outer oxide film where cavities were formed is in accordance with the electrochemical oxidative response.

Radiolysis influences not only the electrochemical behaviour but also the oxide formation of stainless steel in high temperature water environments, like primary water of Pressurised Water Reactors (PWR).
(Invited) Admittance Analysis of Passive Film on Rebar in Solution Simulating Concrete Pore Water
Authors: Inohira Kanaho , Hoshi Yoshinao , Watanabe Hikari , Shitanda Isao , Itagaki Masayuki
Published: December 2020

Steel corrosion is suppressed in concrete because the passive film is formed on the steel surface of rebar owing to the strong alkaline environment inside the concrete. Dawson et al. [1] reported that the corrosion state of steel rebar in concrete can be evaluated by the charge transfer resistance, R
ct, estimated from impedance spectrum. In order to estimate R
ct from impedance spectrum, they [1] proposed an equivalent circuit which includes the solution resistance R
sol, R
ct, electric double layer capacitance C
dl, and Warburg impedance Z
w. An interfacial resistance at rebar/concrete interface was defined as R
ct in the report [1], whereas the authors consider that this interface resistance should be a passive film resistance R
f when passive film is formed on rebar and the interface resistance is very large. It is often difficult to estimate R
f under conditions where the passive film is formed on the rebar surface of the rebar because the impedance locus in the low frequency range does not converge to the real axis of Nyquist plane due to the large value of R
f. In this study, the precise determination method of R
f by the admittance is proposed.

The electrochemical impedance measurement was carried out by a three-electrode system. A rod of carbon steel was adopted as a working electrode. The carbon steel used in the present study has the same composition as rebar which is normally used in actual reinforced concrete structures in Japan. A platinum wire and a saturated KCl silver/silver chloride electrode were used as counter and reference electrodes, respectively. A potentio/galvanostat (Solartron, 1287) and a frequency response analyzer (Solartron, 1255B) were used as measuring devices. In the impedance measurement, the measurement frequency range was from 10 mHz to 10 kHz, the DC potential was corrosion potential, and the AC potential amplitude was 10 mV. A saturated calcium hydroxide solution was used for the test solution to simulate the concrete environment. The pH of test solution was about 12.5.

The impedance spectrum of rebar described a part of semicircle on Nyquist plane. Because the impedance locus in the low frequency range did not converge to the real axis, it is necessary to extrapolate a semicircle from the partial semicircle for the estimation of R
f. The plots of admittance showed a clear semicircle and converged to the real axis in the low frequency range. As high and low frequency limits of admittance correspond to 1 / R
sol and 1 / (R
sol + R
f), respectively, on the real axis of the complex plane, the R
f can be estimated directly from the plots of admittance on the complex plane. The present results suggested that the proposed method can be applied to estimate R
f of rebar in concrete more accurately.

Reference

[1] J. L. Dawson, L. M. Callow, K. Hladky, and J. A. Richardson, Proceedings of
NACE Corrosion/78, Paper No. 125 (1978).
Investigation of Electrochemical Corrosion of SS316L in Different Electrolyte
Authors: Masud Jahangir , Thakare Jivan , Martin Chris
Published: December 2020

Corrosion is defined as the destruction of metals and alloys by chemical or electrochemical reaction with its environment. The corrosion occurs because of the normal trend of metals to come back to their thermodynamically stable native state. Corrosion cannot be avoided, but it can be controlled and prevented by using suitable methods like cathodic protection, anodic protection, metallic coating, alloying and using inhibitors, etc. Of these, the application of inhibitors reduces the aggressiveness of the corrosive and unsafe aqueous surroundings and preventing the metal and alloy from corrosion by forming a protective layer over the metal surface. The corrosion behavior of stainless steel and other metals in seawater has been studied by many researchers [1-2]. Stainless steels (316L) have been used successfully in many applications in the marine environment. 316L is considered to be one of the most resistant of stainless steel under marine environments, and it has excellent mechanical properties at elevated temperatures and easy fabricability. It is an important structural material for many industrial units, especially the desalination plants. 316L is the most likely candidate for saline environment applications due to their excellent corrosion resistance.

The present work was undertaken to study the corrosion behavior of SS 316L metal in different mediums such as Seawater and calcium chloride (Fig. 1) solution by polarization study. The effect of oxygen or air in the electrolyte solution will also be investigated. Corrosion parameters such as corrosion potential, corrosion current, linear polarization resistance, and corrosion rate will be compared and presented in the meeting.

References

[1] Baoping Cai et al., Corrosion Science 52 (2010) 3235–3242

[2] Yong Cui et al., Water Research 88 (2016) 816-825

Figure 1
Influence of Thermomechanical Loads on the Corrosion Behavior of Metal-Polymer-Joints
Authors: Gundlach Christian , Stach Thomas , Menzel Marcus , Dilger Klaus , Hartwig Sven
Published: December 2020

Metal-polymer-joints can be found in multiple today’s major applications like in hybrid car parts in terms of lightweight construction or molded electrical contacts for high-voltage applications. Common to both is the harsh environment they are exposed to including elevated temperature changes inducing thermomechanical stresses based on the differences of the CTE values as well as corrosive media like salty water, solvents or electrolytes. Each promotes its own corrosion mechanism that in most cases comes along with a degradation of the material’s and therefore the part’s performance in service. Especially, two mechanisms have to be considered when dealing with corrosion of metal-polymer-joints. Firstly, corrosion processes of metal and polymer can influence each other as well as the metal-polymer interface layer depending on the material combination. Secondly, thermomechanical stress due to temperature changes can also have an effect on the material’s corrosion behavior. Studying both mechanisms would help to improve the service time of hybrid parts.

The work introduces a new method to investigate corrosion processes in metal-polymer-joints combining the influence of corrosive media and thermomechanical load. A hybrid specimen consisting of a specially formed metal inlay fully surrounded by a potting polymer is used for the measurements. When exposed to cyclic temperature load in a test chamber mechanical stress is induced in the polymer due to the different CTE of the materials. For the measurements typical material combinations used in lightweight construction and high-voltage applications are used. The hybrid specimens are exposed to thermal shocking cycles while being fully surrounded by corrosive media. Throughout the experiment, the specimens are constantly monitored using electrochemical impedance spectroscopy (EIS). In addition, a visual inspection of the specimens takes place after certain times to analyze the overall condition and possible cracks. As a reference, the same setup is applied only to the metal inlays used in the hybrid specimens. By interpreting the results of the EIS measurements, possible corrosion processes of metal and polymer as well as their correlation can be characterized in detail. Additionally, the comparison of hybrid specimens and raw metal inlays reveals the influence of the thermomechanical load on the corrosion process. The experimental part is supported by FE-simulations, which are also supplementary presented in this investigation.
Corrosion Inhibition of AA2024-T3 By Smart Polyelectrolyte Coacervates Responsive to Both Acidic and Alkaline Environments
Authors: Li Chao , Guo Xiaolei , Frankel Gerald S.
Published: December 2020

Previously reported pH-responsive corrosion-protective coatings based on the layer-by-layer assembled polyelectrolytes responded to either a pH increase or decrease caused by cathodic or anodic reactions in corrosion, respectively, but not to both. The layer-by-layer technique, which is the standard method to prepare these coatings, requires dozens of layers to make the coatings useful for corrosion protection by safely enclosing corrosion inhibitors. In this study, polyacrylic acid was directly added into polyethylenimine to make polyelectrolyte coacervates via electrostatic interactions. The coating consisting of polyelectrolyte coacervates was capable of entrapping the SrCrO4 inhibitor and releasing the inhibitor at both acidic and alkaline pH. The concentration of released SrCrO4 exceeded the threshold for the corrosion protection of AA2024-T3 and the corrosion resistance of AA2024-T3 was improved, as evidenced by electrochemical methods including cyclic potentiodynamic polarization and electrochemical impedance spectroscopy. The developed polyelectrolyte coacervates open a pathway for creating a dual-pH release system in a facile and fast way, which can be applied as main components in active corrosion-protective coatings for Al alloys.
Thermal Isotropic Atomic Layer Etching of Metallic Molybdenum
Authors: Fischer Andreas , Routzahn Aaron , Lill Thorsten
Published: December 2020

In high aspect ratio structures such as 3D NAND stacks, high-k oxides or certain metals need to be removed from sidewalls and even non-line-of-site locations where access via reactive ion etching would be challenging or impossible. To achieve etching in these locations, thermal processes need to be applied that lack any intrinsic directionality and are therefore isotropic. Thermal Atomic Layer Etching is one option to facilitate this kind of process. Therefore, it has gathered significant attention recently and is now being explored in academia and industry.

In this work, we demonstrate isotropic Atomic Layer Etching on metallic molybdenum using a three-step process that involves oxygenation of the metal surface, a conversion reaction using boron-trichloride followed by a hydrogen-fluoride clean step. We measured the etch rate per cycle to be around 10 Å with low temperature dependence in the range between 150°C and 250°C.

Furthermore, we examined the effectiveness of various oxygenation methods on the surface of metallic molybdenum films. These methods included thermal oxygenation as a function of temperature, oxygenation by a remote plasma and in-situ plasma fluorination. We established that an oxygenation level of more than 70% as measured with XPS is needed in order for the ALE process to work. Levels in this range could be achieved via in-situ plasma oxygenation as well as with a remote plasma. Thermal oxygenation, on the other hand, required substrate temperatures in access of 400°C to oxygenate at the 70% level.

In this study we also show an example of molybdenum ALE in an application that involved the removal of this metal from a 50:1 aspect ratio 3D NAND structure. We measured etch rates on vertical and horizontal surfaces as well as the depth dependence in removal rate of molybdenum.
The Metal Gate Cut Process Development
Authors: Ji Shi-liang , Han Qiu-Hua , Zhang Hai-Yang
Published: December 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 only 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 20nm, the height is over 100nm, 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 conduction will greatly increase the plasma induce damage risk, which needs to be controlled by properly selecting photo and etching conditions.

We will start a study on the above issues and discuss the development direction and research ideas in each aspect. This manuscript will focus on plasma etching development during metal gate cut process. The CD shrinkage is very critical process 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. Another part will focus on metal cut etching process, cycle model is benefit to so many kinks of materials. Vertical profile show trade-off and ILD loss, we found the different design and requirement need to adopt different ILD remaining approach. At the same time, low Te etch process is key to avoid plasma induce damage.
In Situ Deposition of Platinum-Group Metals for Electrocatalytic Hydrogen Peroxide Production By Oxygen Reduction
Authors: Wang Yu Lei , Gurses Sadi , Felvey Noah , Bayoglu Ozge , Kronawitter Coleman X
Published: December 2020

Hydrogen peroxide (H2O2) is a valuable commodity chemical that serves as a disinfectant for a number of important chemical end-use applications and as an oxidant for a several emerging technologies for oxidative chemical transformations. Recently there has been a resurgence of interest in the electrocatalytic production of H2O2 by oxygen reduction because it has been recognized to be compatible with the general concept of distributed chemical manufacturing, which in many cases presents strategic advantages over conventional operations based on centralized, large-scale systems. When compared with conventional synthesis technologies, electrocatalytic production of H2O2 – which uses only air, water, and electricity as inputs – is amenable to greater geographic distribution and shows strong potential to be cleaner and more sustainable.

This presentation will describe efforts to utilize platinum-group metals as electrocatalysts for the cathodic reduction of O2 to H2O2 in water. Platinum-group metals are prototypical fuel cell catalysts and generally regarded to be non-selective to H2O2. The presented results will show that in certain electrodeposition synthesis conditions, these metals can form the basis of engineered electrodes that are both highly selective and active for cathodic H2O2 production by oxygen reduction. The use of these metals presents an engineering advantage because they are acid-stable, and therefore (1) compatible with existing PEM fuel cell cathode environments and (2) produce H2O2 in the low-pH environment where its stability is maximized. This presentation will discuss the physical, structure, and chemical properties of electrocatalysts that correlate with high H2O2 selectivity, and the fundamentals of the electrodeposition technique by which they are synthesized.
(Invited) Power-to-Value: Metal Foam Catalysts for the Electrochemical Conversion of CO2
Authors: Dutta Abhijit , Rahaman Motiar , Kiran Kiran , Zelocualtecatl Montiel Ivan , Cedeño López Alena , Moreno-García Pavel , Broekmann Peter
Published: December 2020

The electrochemical conversion of CO2 (denoted as CO2RR) has attained significant interest in the catalysis research worldwide over the recent years as it provides means of transforming an environmentally harmful molecule back into products of higher value (e.g. high energy density fuels, chemical feedstock and useful commodity chemicals such as carbon monoxide). This process becomes particularly sustainable when using the surplus of electric power produced from renewable hydro, wind or solar sources (power-to-value concept). Substantial progresses have already been made during the last decade in the tailored design of novel catalyst materials needed to increase the energy efficiency of the CO2/water co-electrolysis and to guide the product distribution reaction into the desired direction. These progresses remained, however, restricted to the fundamental research whereas no technologically and economically feasible process could be established on an industrial scale so far. One key challenge left is related to the particular stability of the catalyst materials, a crucial pre-requisite for any industrial application of catalytic processes.

In this contribution, concepts for the design of monometallic and bimetallic CO2RR catalysts will be discussed that are based on the additive-assisted electroplating of high-surface area metal foams. Main target products of the CO2RR addressed herein are formate (Bi foams), syngas (Ag foams; see Figure below) as valuable chemical feedstock for a subsequent non-electrochemical conversion process (Fischer-Tropsch, Rheticus process/Siemens-Evonik), and high energy density fuels (e.g. ethanol, n-propanol; bimetallic AgCu foams and co-alloed PdCu foams). Advanced operando Raman spectroscopy will be demonstrated to be highly useful for the identification of active catalyst species under CO2 electrolysis conditions.

Figure 1
(Invited) Electrodeposition for Metals Extraction and Recycling
Authors: Allanore Antoine
Published: December 2020

A sustainable energy future is metal-based, being directly supported by structural metals (Fe, Al) or by products of metal extraction and mining (Cu, Ni, Co, precious metals,Rare-earth). We herein discuss how electrodeposition, as an engineering practice, has a role in supporting such future, being in the context of primary metal extraction or recycling. Informed by chemical thermodynamics realities and engineering challenges such as productivity, it is proposed to discuss how the issue of selectivity coupled with transport phenomena is in need of attention if considering possible application of electrodeposition. Some recent developments in electrochemical methods to investigate electrodeposition as well as insights from metal separation challenges will be used as supporting examples.
Controllable Electrodeposition of Co-Ni-S on Carbon Paper for Electrocatalytic Hydrogen Evolution Reaction
Authors: Guo Wen Wu , Ahn Sang Hyun
Published: December 2020

Development of highly active catalyst for hydrogen evolution reaction (HER) is an urgent research to realize the energy consumption transformation from fossil flue to clean and renewable hydrogen energy and alleviate the energy crisis and. Electrochemical water splitting offers an ideal approach for hydrogen production with ultrahigh purity, which need a cost-effective electrocatalyst to drive the HER. Until now, Pt-group metals have been proved to be the best electrocatalysts for HER due to the extraordinary low overpotential near the thermodynamic potential of HER, but their widespread commercial application on a large scale is hampered by the prohibitive cost and scarcity.

In this study, we reported amorphous Co-Ni-S catalysts fabricated on carbon paper by a simple one-step electrodeposition. By varying the deposition potential/time and concentration of sulfur source, the morphologies and compositions of Co-Ni-S were controlled, and optimal condition for synthesis was obtained. The structure, surface morphology and composition of deposits were characterized in detail. And the electrochemical performance and stability of catalysts were tested in alkaline media by directly using the as obtained Co-Ni-S/Carbon Paper as a cathode. The characterization results showed Co-Ni-S was amorphous and uniformly deposited on carbon paper. And the electrochemical test indicated that Co-Ni-S/Carbon Paper has acceptable performance with low overpotentials of 99mV at 10mA/cm2, Tafel slop of 85mV/dec and long-tern durability. Moreover, the double-layer capacitance (Cdl) result indicated that Ni−Co−S catalyst possesses high electrochemical surface area (ECSA), which could provide abundant active sites for electrocatalytic reaction
Ultrathin RF-Sputtered Lipon Layers for Conformal Lithium Deposition
Authors: Wodarz Siggi , Kee Yongho , Cotte Stéphane , Mees Maarten , Barde Fanny , Vereecken Philippe M.
Published: December 2020

The transformation from liquid-based Li-ion batteries to solid-state Li-metal batteries is a necessary step to achieve beyond energy densities of 1000 Wh/L. However, the commercial widespread application of the solid-state Li-metal batteries has been hindered by several electrolyte constraints, among which narrow electrochemical window and low compatibility against metallic lithium as negative electrode. Among the various solid-state electrolytes, nitrogen doped lithium phosphate glass or LiPON is a well-known material with an excellent electrochemical stability above 5 V and a good compatibility against metallic lithium [1]. However, owing to its low ionic conductivity (~10-6 S/cm), application of LiPON is limited for thin-film batteries in medical implants and various sensor systems. For thin-film batteries, because the path length for Li+ ion diffusion is in the order of few 100 nm or less, low conductivity of LiPON is enough for application. LiPON has also been evaluated as solid-electrolyte coatings on electrode particles as buffer layer between active material and the bulk electrolyte. In a thin-film stack, it is an ideal model system for electrochemical study.

Previously, we investigated detailed electrochemistry of RF-sputtered LiPON thin films with different thickness [2]. We demonstrated formation of an electronically insulating LiPON films down to 15 nm with a maximum conductivity of 1×10-6 S/cm. We have also formulated a breakdown mechanism for LiPON layer based on experimental measurements and thermodynamic considerations. In the present work, we investigated LiPON thin-films as artificial solid-electrolyte interphase for lithium plating and stripping on copper current collectors. The stability of 100 nm down to 10 nm LiPON thin-films was evaluated by electrochemical galvanostatic cycling test of Li plating/stripping with carbonate-based electrolyte. The LiPON thin-film with 100 nm showed reversible plating/stripping of Li with an overpotential of only ~40 mV for current density of 0.1 mA/cm2 for over 100 cycles, indicating formation of a uniform Li layer in-between substrate and LiPON without breaking of LiPON layer during the cycles. Furthermore, even with the thickness of only 10 nm, LiPON thin-film demonstrated significant improvement of coulombic efficiency of Li plating/stripping compared to without LiPON layer. In the presentation, thickness-dependence of LiPON on growth behavior of Li will be further discussed.

Reference

[1] X. Yu, J. B. Bates, G. E. Jellison, Jr., and F. X. Hart, J. Electrochem. Soc., 144 (1997) 524-532.

[2] B. Put; P.M. Vereecken; J. Meersschaut; A. Sepúlveda; A. Stesmans, ACS Appl. Mater. Interfaces., 8 (2016) 7060-7069.
Novel One-Step Electrophoretic Deposition of Membrane-Electrode Assembly for Flexible Batteries Application
Authors: Golodnitsky Diana , Cohen Elazar , Lifshitz Moran , Gladkikh Alexander , Kamir Yosef , Ben Barak Ido
Published: December 2020

The focus on shifting towards miniaturized products coupled with the booming demand for consumer electronics are some of the key-driving factors behind the flexible-battery market. In the development of innovative power sources, freeing from design limitation along with the synthesis of reliable electrochemical materials with well-tuned features, is considered to be the most important technical prerequisite.

In the current research we present for the first time, a unique, single-step method for the preparation of a membrane-electrode assembly for flexible-batteries application. Concurrent electrophoretic deposition (EPD) of positive and negative battery electrodes (LFP and LTO) on opposite sides of a commercial nanoporous membrane (Celgard 2325) results in the formation of a three-layer-battery structure. The cell comprising this electrophoretically deposited structure ran for more than 150 cycles with 125-140mAh/g capacity, which approaches the theoretical value of lithium iron phosphate. The electrodes can be deposited either cathodically or anodically by replacing the interchangeable charging agents, like polyethyleneimine and polyacrylic acid. These polyelectrolytes, when adsorbed on the particles of the active material, serve also as the binders. The simultaneous EPD, which we developed, can be used for the simple and low-cost manufacturing of a variety of cathode and anode materials on nanoporous polymer- and ceramic ion-conducting membranes for energy storage devices
Silicon-Graphite Anode with High-Areal Capacity for Li-Ion Battery
Authors: Li Peng , Han Geumjae , Sun Yang-Kook
Published: December 2020

Nowadays, researchers are increasingly interested in silicon active material for lithium-ion batteries, which could meet the ever-increasing demand for high energy density owing to their satisfactory theoretical capacity (~4200 mAh g-1). Nevertheless, replacing the commercial graphite totally with silicon is still insurmountable due to bottlenecks such as low loading level and unsatisfactory areal capacity. Therefore, in this work, we turned eyes back on improved graphite anode with modified silicon cooperation through a facile blending process. The nano/microporous silicon active mateiral with boron doping and carbon nanotube wedging (B-Si/CNT) exhibits stable electrochemical performance (88.2% retention after 200 cycles at 2000 mA g-1) and high reversible capacity (ca. 2400 mAh g-1). After graphite cooperation, the resultant B-Si/CNT-graphite composite could illustrate an areal capacity of 5.2 mAh cm-2 with a high mass loading (11.2 mg cm-2). Besides, the enhanced anode also demonstrates acceptable utilization in lithium ion full battery with 2 mol% Al-doped full concentration gradient Li[Ni0.76Co0.09Mn0.15]O2 as cathode, showing a good energy density of ca. 8.0 mWh cm-2. Furthermore, considering that low initial coulombic efficiency (ICE) of silicon is another drawback for its industrial application, tough graphite framework and optimized lithium polyacrylate binder could be applied to increase the ICE effectively.

Reference
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1. U.-H. Kim, S.-T. Myung, C. S. Yoon and Y.-K. Sun, ACS Energy Lett.
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2. J. H. Lee, C. S. Yoon, J.-Y. Hwang, S.-J. Kim, F. Maglia, P. Lamp, S.-T. Myung and Y.-K. Sun, Energy Environ. Sci., 2016,
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3. P. Li, J.-Y. Hwang and Y.-K. Sun, ACS Nano,
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Figure 1
Alloy-Composite Electrodeposition with a Rotating Hull Cell
Authors: Podlaha Elizabeth J. , Zhang Yujia
Published: December 2020

A Hull cell is a convenient tool to quickly survey resulting deposit compositions with current density – a tool used for alloy deposition by Nobe years ago. The Hull cell can also be used to provide information to better understand the deposition mechanism and kinetic-transport behavior. Together with linear sweep voltammetry, rotating Hull cell data was used to determine the partial current densities of Ni and W metal ion reduction to examine induced codeposition during the co-deposition of metal-titania composites. The Ni-W-TiO2 system is of interest as an electrocatalyst for the hydrogen evolution reaction (HER) from water reduction in alkaline electrolytes. The results indicated that the amount of titania nanoparticles incorporated into electrodeposited Ni-W-TiO2 influenced the metal ion reduction behavior favoring the nickel ion reduction rate at large applied potentials where the hydrogen evolution side reaction was significant. In this region the particles also increased the hydrogen evolution side reaction rate. Not only was the HER enhanced during the deposition electrolyte in the presence of titania particles, the HER in 1 M NaOH was also enhanced when the particles were embedded in Ni-W-TiO2.
Molecularly Imprinted Polymer for Selective Electrosynthesis of Biphenols
Authors: Sudagar Alcina Johnson , Borowicz Pawel , Asztemborska Monika , Kutner Wlodzimierz , Noworyta Krzysztof R.
Published: December 2020

Molecularly imprinted polymers (MIPs) have been widely studied for sensing and separation of compounds selectively. These artificial biomimicking recognition units are highly sensitive and selective to target analytes. Electrochemical preparation of MIPs offers advantages including ease of preparation as well as control over the polymer nucleation and growth, thickness, and film morphology. Moreover, it is possible to follow the formation of cavities electrochemically through the gate effect. Few reports have focussed on selective catalysis by using MIPs. However, the application of these MIPs in the field of electrocatalysis remains unexplored and, therefore, there is a large research scope in this domain.

Biphenols are structural motifs of several molecules in nature and for many drugs. They are efficient ligands for catalytic systems and are highly stable under electrochemical condition. In particular, 3,3,5,5-tetramethyl-2,2-biphenol acts as a significant backbone in phosphorus-based ligand systems for calatysis. The oxidation of 2,4-dimethylphenol yields several different products including polycyclic compounds formed by C-H bond activation (Scheme 1). Therefore, designing a scalable process, in which the desired biphenol is selectively produced, is challenging.

In the present work, we aim to develop MIPs that can be applied for selective electrosynthesis of the desired C-C coupled biphenol through electro-oxidation of the corresponding phenol. For this purpose, the functional monomer was selected based on the Gibbs free energy of its interaction with the target biphenol template in density functional theory (DFT) simulations. Complexation of the functional monomer with the template was confirmed by spectroscopic titrations. Electroactive monomers can polymerize to form either conducting or nonconducting polymers. In our system, a conductive MIP film was prepared using derivatized thiophene functional monomers. Then, the template extraction process was optimized. Electro-oxidation of 2,4-dimethyl phenol was studied in detail to reach as high yield as possible of the desired biphenol product at a bare platinum electrode. HPLC-MS was used to identify the substrate and products of the electrosynthesis. Then, selectivity of the electrosynthesis study was performed for the MIP film-coated electrode in comparison to a non-imprinted polymer (NIP) film-coated electrode, and a bare electrode.

Figure 1
Electrospun Nanofibers for Applications in Energy Harvesting and Generation
Authors: Yu Sooyoun , Chen Qi , Yang Steve , Chen Wilfred , Myung Nosang Vincent
Published: December 2020

Nanofibers have long been exploited as a versatile, attractive material compared to their bulk counterparts due to their exceptionally high specific surface area and aspect ratio, highly porous structure, and wide range of materials that can be used for synthesis. Such unique properties helped exhibit their potential in a variety of applications in areas of energy, healthcare, and environment. Applications in energy are widely studied especially because of the global need for a source of energy and method of energy production that is alternative to the combustion of fossil fuels, as it presents many environmental drawbacks, which ultimately lead to adverse health effects on humans. To bypass the use of fossil fuels, renewable sources such as wind, hydro, geothermal, and solar energy have been introduced; devices that take advantage of alternative sources of energy such as nanogenerators, fuel cells, and thermoelectric generators have been developed.

In this work, hybrid nanofibers were fabricated with precise control of the working parameters to fine tune their properties for various applications, including piezoelectrics and enzymatic fuel cell electrodes. Pure polyacrylonitrile (PAN) nanofibers were first electrospun based on a series of design of experiments to minimize both the diameter and beading. By correlating the solution, electrospinning, and environmental conditions to the resulting solution and nanofiber properties, it was found that not only physical properties such as electrical conductivity but also electrochemical properties of the nanofibers could be controlled. Physical and electrochemical properties of porous carbonaceous nanofibers derived from PAN, zinc acetate and multi-walled carbon nanotubes were studied with SEM, 4-point probe measurement, CV, LSV, and EIS. Based on the electroanalytical methods, the best nanofiber mats were chosen and used as electrodes to immobilize multienzyme cascade systems, a concept of which was demonstrated with a glucose oxidase-BglA bienzymatic system on a customized DNA scaffold as the anodic biocatalyst.
Microstructure-Tailored Ni-Rich NCA Cathode for Next Electric Vehicles
Authors: Ryu HoonHee , Sun Yang-Kook
Published: December 2020

Li[NixCoyAl1-x-y]O2 (NCA) cathodes have been adapted for the current fleet of electric vehicles, which still have unsatisfactory performances. To further increase the driving range, the Ni content in NCA cathodes should be progressively increased so that the energy density of the lithium-ion batteries is increased. However, an inherent trade-off relation between delivered capacity and cycling stability is clearly observed in Ni-rich NCA cathodes: the capacity gain from Ni enrichment is negated by the rapid capacity fading. The most dominant mechanism for the rapid fading is the microcrack formation of the cathode particles.1,2 Microcracks undermine the mechanical integrity of the Ni-rich NCA cathodes and allow the electrolyte to penetrate the particle interior, thus leading to parasitic surface reactions. Although various attempts, such as optimizing transition metal composition, finding effective doping or coating agents, have been proposed to improve the cycling stability of Ni-rich cathodes, these approaches are not a fundamental solution to the formation of microcracks on the particle.

Recent researches provided valuable insights into a way to suppress microcrack formation.3 Because microcracks nucleate from the abrupt lattice contraction caused by the multiple phase transition during the electrochemical reaction, it is necessary to minimize the local strain build-up for particle integrity. Although intrinsic lattice volume changes are unavoidable during electrochemical reactions, the structural integrity of Ni-rich cathodes can be preserved by engineering the microstructure of cathode particles such that the strain distribution is delocalized.4 In this presentation, we propose boron-doped Li[Ni0.878Co0.097Al0.015 B0.01]O2 (B-NCA88) which have obviously different morphologies compared to a typical NCA cathode. To highlight the dramatic microstructure change caused by boron doping, B-NCA88 and typical Li[Ni0.885Co0.1Al0.015]O2 cathodes are extensively investigated by comparing their electrochemical properties, microcracking behavior, and structural stability.

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K.-J. Park, J.-Y. Hwang, H.-H. Ryu, F. Maglia, S.-J. Kim, P. Lamp, C. S. Yoon and Y.-K. Sun, ACS Energy Lett.
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Electroless Deposition of Ni-P Composite and Multilayer Coatings: Applications and Perspectives
Authors: Magagnin Luca
Published: December 2020

Considerable economic losses occur every year due to erosion-corrosion in parts of machines and equipment during service. In order to reduce this loss, properties of the surface of the materials should be improved. Among the various surface processes, electroless plating is one of the appropriate methods to deposit coatings on metals without applying an external electrical voltage, which provides coatings with uniform thickness, crack free nature, appropriate adhesion to the substrate, high hardness, and high wear resistance. The electroless deposition is a promising method to prepare durable metal films on both conducting and non-conducting substrates of different geometries. In the present study, Ni-P composite coatings were successfully electroless plated on mild carbon steel from acidic baths reinforced with ceramic and polymeric micro and nano-particles, as single and multilayer deposits. The effect of the electrolyte composition as well as the nature of the dispersed phase on the phosphorus co-deposition, particles incorporation, surface morphology and structure of the deposits have been investigated and evaluated. The use of multilayer or hybrid techniques in surface engineering has often been cited as the way to improve the mechanical, tribological and electrochemical properties of coatings. Especially, the multilayer coating with layers having different corrosion potential Ecorr was an effective solution to improve the corrosion-resistance of the no-sacrificial coatings. Multilayered coatings were produced by stacking layers of different composition by successive electroless plating with rinsing steps in between. This study will discuss new applications and perspectives of these coatings as anti erosion-corrosion surface treatments. The impact of the plating approach on the microstructure of the coatings as well as on their mechanical properties and corrosion resistance is presented.