bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Grain Size on the Corrosion Behavior of Mg-RE Alloy ZE10A
Authors: Shrestha Nikunja , Kersten Bethany R , Zillinger James , Utgikar Vivek , Raja Krishnan S.
Published: February 2020

Mg-RE alloy Electron717 (ZE10A, UNS M11600) has a nominal composition of 1.2wt % Zn, 0.25wt% Zr, <0.5%Zr, 0.007wt%Mn, 0.004wt %Fe,0.001wt%Ni and balanced Mg. Zirconium addition acts as a grain refiner, so it helps increase castability, mechanical properties and provide better corrosion resistance.1
ZE10A alloy may have better corrosion resistance than unalloyed Mg. Even though formation of Zn2Zr3 type precipitates has been suggested in this type of alloy, heat treatment in the temperature range of 200 – 300 ºC for different time periods did not show significant increase in the hardness. Therefore, this alloy is considered not age hardenable. Brady et.al showed that ZE10A alloy forms a dual layered passive film with inner layer rich in MgO and outer layer of Mg(OH)2.2 The formation of two layers make it more resistant to corrosion. This presentation will focus on the corrosion behavior of the ZE10A alloy as a function of grain size, and the hydrogen evolution behavior in different electrolytes.

The alloy was investigated in three different heat-treated condition such as (1) As received (grain size of 7.90 µm), (2) Solution treated at 525oC for 8 hours (grain size of 26.24 µm) and (3) Solution treated at 525oC for 24 hours (grain size of 41.37 µm). Anodic and cathodic polarizations were carried out in three different electrolytes (pH unadjusted) such as:

1) 0.6M NaCl

2) 0.5M NaNO3

3) 0.1 M Na2SO4

Table 1.0 Summary of anodic and cathodic polarization results of ZE10A alloy in different heat-treated conditions and in three different solutions.

Table 1 summarizes the polarization results. The polarization resistance decreased with increase in the grain size in all the electrolytes, in general. The corrosion current density increased with the grain size. Higher corrosion current densities were observed in the Na2SO4 solution than that in the other two electrolytes. The anodic Tafel slopes are found to be higher in the Na2SO4 solution than in NaCl and NaNO3, whereas, cathodic Tafel slopes did not reveal a clear trend of variation either with the grain size or type of electrolyte. The presentation will focus on how the microstructures in terms of grain size, and secondary phase distribution influence the corrosion behavior of the ZE10A alloy based on the experimental results and literature review.

[1] N.T. Kirkland et.al JOM, 2011, 63(6)28-40

[2] M.P.Brady et. al Scripta Met. 106(2015) 38-41

Figure 1
Electrochemical Investigation of the Role of Alkaline Pretreatment in Anticorrosion Performance of Silicone-Epoxy Coatings on 2024 Al-Alloy
Authors: Yuan Xin
Published: February 2020

The anticorrosion performance of the silicone-epoxy coatings on 2024 Al-alloy with different surface pretreatments were systematically evaluated in 3.5 wt.％ NaCl solution by potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electrochemical microscopy (SCEM), poll-off test and ultra-depth three-dimensional microscope (UTM). Based on hypothetical corrosion mechanism, electrical equivalent circuits (EECs) were developed and simulated to correspond to the experimental EIS data. The cross section and morphology of the Al-alloy subjected to different pretreatments and the coatings were characterized using UTM. The delaminated area and the roughness of the interfaces were discussed from their respective break-point frequency and fractal dimensions deduced from EIS data. The SCEM redox competition mode, in which smaller tip current reflects severer corrosion reaction at the defect, was used to monitor the local corrosion behavior of the Al-alloy substrate under the scribe. The average adhesion of the coatings on the samples were evaluated using pull-off adhesion tests before and after immersion in a NaCl solution. Based on the above test results, a specific alkaline pretreatment of the Al-alloy prior to the coating has been found to improve the corrosion resistance of the Al-alloy.
Long-Term Corrosion Testing of Inconel Alloy 625 in Molten LiCl-Li2O-Li
Authors: Phillips William , Chidambaram Dev
Published: February 2020

Introduction

In order to incorporate oxide based nuclear fuels from the current light water reactor fleet into a pyrometallurgical based fuel cycle, it is necessary to reduce the oxide fuel to a metallic form. This process is typically conducted electrolytically in a LiCl-Li2O electrolyte at 650°C. Due to the close reduction potentials of UO2 and Li2O, metallic Li is generated at the cathode and subsequently dissolves into the electrolyte, forming a tertiary LiCl-Li2O-Li solution. This study examines the long term corrosion behavior of Inconel 625 when exposed to LiCl-Li2O-Li solutions for 500 and 1000hr.

Experimental

Similar to our previous work on SS316, exposure testing was performed in LiCl with 1 or 2 wt%Li2O and 0, 0.3, 0.6 and 1.0wt%Li at 650°C for 500 and 1000 hours. I625 samples were polished to a 0.05μm surface finish prior to exposure. The salt solutions were replaced every 96 hours to make up for evaporation and reaction of Li and/or Li2O to ensure consistent solution chemistry. Following exposure, the samples were rinsed with methanol and analyzed using Raman spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and micro-Vickers hardness testing.

Results

The primary corrosion products detected via Raman spectroscopy, XPS, and EDS on samples exposed to LiCl-Li2O solutions in the absence of Li were lithium chromite, nickel-iron-chromium spinel oxides, and lithium chromate. XRD confirmed the presence of lithium chromite on these samples. In the presence of Li, these surface layers were destabilized and the surface of the samples were free of any significant oxide film, while titanium oxynitride films of nm thickness were observed via XPS. The surface morphology of the samples was observed via SEM to undergo increased degradation with higher concentrations of Li.

Acknowledgements: This work was performed under the auspices of the Department of Energy (DOE) under contracts DE-NE0008262 and DE-NE0008236, and the US Nuclear Regulatory Commission (NRC) under contracts NRCHQ-11-G-38-0039 and NRC-HQ-13-G-38-0027. W.P. acknowledges the Fellowship Award from the NRC. Dr. Kenny Osborne serves as the program manager for the DOE award and Ms. Nancy Hebron-Isreal serves as the grants program officer for the NRC awards.
The Influence of Aluminum Nitrate Pre-Treatment on High Temperature Oxidation Resistance of Dip-Coated Silica Coating on Galvanized Steel
Authors: Yang Tzu-Chin , Chang Jun-Kai , Lin Chao-Sung
Published: February 2020

Hot-dip galvanization is one of the common methods for anti-corrosion treatments on steels nowadays. Zinc coating on galvanized steel enhances the corrosion resistance of the steel substrate through barrier protection and sacrificial protection. However, its application on press hardening steel (PHS) is facing some challenges. During the austenitization treatment of PHS, the use of zinc coating results in severe liquid metal induced embrittlement and high temperature oxidation.

This present study focused on the effect of aluminum nitrate pre-treatment on the properties of the subsequent silica coating, including the adhesion and high temperature oxidation resistance of the coating. Aluminum nitrate pre-treatment was employed to precipitate aluminum oxide and hydroxide on the substrate in order to provide a homogenous surface and improve the oxidation resistance. The silica coating was synthesized by a sol-gel method from tetraethoxysilane (TEOS) and 3-glicidoxipropyl-trimetoxisilano (GPTMS) precursor solution. The silica coating was applied via dip coating on a commercial hot-dip galvanized steel received from the China Steel Corporation, Kaohsiung, Taiwan, and was subsequently cured to confer high temperature oxidation resistance. The high temperature oxidation resistance was evaluated using the thermal gravimetric analysis (TGA, TA Q50) and the microstructural evolution during austenitization. Experimental results showed that the silica coating with pre-treatment had better high temperature oxidation resistance and hindered the liquid phase evaporation. Therefore, it is evident that the aluminum nitrate pre-treatment had positive effects to suppress high temperature oxidation. The Auger spectroscopy analysis further revealed that the surface of the hot-dip Zn coating became chemically homogeneous after the aluminum nitrate pre-treatment, signifying the necessity of a homogeneous aluminum hydroxide surface layer to enhance the adhesion and oxidation resistance of the silica coating on hot-dip galvanized steel during austenitization.

Keywords: Press hardening steel; Hot-dip galvanized steel; Silanes; Sol-Gel; Pre-treatment
(Invited) Chain Length Variation to Probe Mechanism of Accelerator Additives in Copper Electrodeposition
Authors: Gewirth Andrew A , Schmidt Ralf , Schmitt Kevin Gary , Rooney Ryan
Published: February 2020

We evaluate the mechanism of Cu deposition in the presence of additives of different chain lengths to provide design guidelines for electroplating additives in the specific context of Cu electroplating. The effects of chloride and a series of sulfonic acid additives were assessed using a combination of electrochemical and Raman spectroscopic methods. Rotating disk linear sweep voltammetry revealed the influence of these additives on the bulk concentration of Cu+ and on the exchange current densities of the reduction of Cu2+/Cu+ and Cu+/Cu. We then used in situ shell-isolated, nanoparticle-enhanced Raman spectroscopy to correlate the additives’ effects on deposition kinetics with their chemical structures at the electrode surface. The combination of these methods suggests that effective Cu electrodeposition acceleration processes require: 1) direct tethering of mercaptoalkylsulfonate species to the electrode, 2) partial desolvation of Cu2+ by the sulfonate group to minimize its solvent reorganization energy, and 3) stabilization of Cu+ adjacent to the electrode surface by addition of halide.
CuNi Alloy Electrodeposition for Microbumps Using Benzotriazole
Authors: Haesevoets Karel P , Radisic Aleksandar , Vereecken Philippe M.
Published: February 2020

A pressing issue in flip-chip and stacked integrated circuit (SIC) technology is the breakdown of microbumps over time. These microbumps are the physical and electrical connections between the chips. They consist out of Cu stages on both chips which are typically soldered together by Sn. Due to diffusion and electromigration, Cu and Sn form two intermetallic phases of which Cu3Sn induces microvoids at the Cu3Sn/Cu interface causing in turn breakdown of the microbump. Chemical modelling shows that a CuNi alloy, with an approximate 9:1 Cu:Ni ratio, together with Sn doesn’t form the Cu3Sn intermetallic compound thus tremendously improving the stability of the microbumps, and therefore the chip. By far the most feasible method to manufacture microbumps is galvanostatic electrochemical deposition. However, electrochemical CuNi co-deposition from a single deposition bath requires current densities higher than the limiting current density of copper causing rough, uncontrolled dendritical growth of Cu. Existing CuNi baths are citrate based but citrates can corrupt other features of the chip manufacturing process.

In this work the possibility of smooth, solid solution electrodeposition of CuNi in a 9:1 ratio using benzotriazole (BTA) is investigated. Benzotriazole is a well-known corrosion inhibitor for copper. Here we show that BTA has a tremendous potential for suppressing Cu2+ reduction and limiting the uncontrolled mass-transfer limited Cu growth. First we demonstrate with a RDE voltammetric investigation, together with viscosimetry, the effects of the combination of an existing CuSO4 and a NiSO4 bath on Cu2+ reduction. Then, we introduce BTA and show the large difference between the working of BTA in the combined bath and in a CuSO4 only bath. Later, we improve the working of BTA by increasing the pH thus defining a parameter window for which we’re able to deposit CuNi with a maximum suppressing effect of BTA. CuNi deposits on metal pellets with a Cu substrate layer are investigated by SEM and EDX to evaluate the morphology and elemental composition of the deposit. We were able to demonstrate the change in CuNi morphology upon increasing the BTA concentration from 0 to 1000 ppm. No distinction could be made in Cu or Ni rich areas over different deposit areas indicating that we’re able to deposit CuNi as a solid solution.

Figure 1
Multi-Scale Modeling for Redox Flow Battery Electrode
Authors: Wang Wei , Bao Jie
Published: February 2020

For redox flow batteries, the reaction distribution in macro or device-scale has been studied, however the reaction distribution in pore-scale is not well understood. Moreover, the understanding on how the reaction distribution in pore-scale impact the overall flow battery performance is lacking. This study introduces a framework that can provide the multi-scale path that help researchers understand the relationship between pore-scale electrode structure reaction and the device-scale electrochemical reaction uniformity for the redox flow batteries. A reduced model is build based on the 128 pore-scale simulations, which provide a quantitative relationship between the battery operation conditions (inlet velocity, current density, inlet concentration) and the surface reaction uniformity for the pore-scale sample. The multi-scale framework upscale the pore-scale surface reaction uniformity to device-scale combine uniformity. The inlet velocity can be optimized based on this multi-scale framework, and a time-varying inlet velocity can be derived for an example flow battery setup. It shows that keeping a constant inlet flow rate for the entire charging period waste much pump power comparing to the optimized time-vary inlet flow rate. Figure 1 shows the optimized flow rate and inlet concentration evolution with color lines represent various flow rate for different target normalized standard deviation of surface reaction rate.

Figure 1
Leveraging Nano-Confinement Properties of Room Temperature Ionic Liquids for Sensitive Detection of Biomolecules in Complex Biological Buffers
Authors: Jagannath Badrinath , Muthukumar Sriram , Prasad Shalini
Published: February 2020

The analytical sensor performance metrics for biomolecular interactions are dependent on the charge-screening effects of the buffer at the electrode/solution interface. High ionic nature of buffers may reduce sensitivity due to increased charge-screening. Typically, for biosensing using non-faradaic electrochemical systems, charge-screening needs to be avoided at the electrode/solution interface for reliable detection of affinity based biomolecular detection. Room temperature ionic liquids (RTIL) consist of charged moieties that form compact electrical double layer (EDL) around the capture probe antibody in an affinity based immunoassay, providing enhanced stability. Further, RTIL moieties also provide nano-confinement of the biomolecular capture probes, thus, enhancing the sensitivity in detection of target analyte. However, the biosensor performance metrics may vary upon interaction with various biological buffers such as serum, saliva, sweat. In this work, we investigated the impact on biosensor metrics due to interaction between RTIL moieties and biological buffers (serum, saliva and sweat). Zeta potential measurements were used to characterize the interaction between capture probe in RTIL and complex biological buffers. The surface charge properties of biomolecules using zeta potential measurements indicated no-charge screening effects of the biomolecules in the presence of RTIL moieties with serum, saliva and sweat buffer. This is primarily due to the formation of compact EDL around the biomolecular capture probe. This property was used to leverage a highly sensitive affinity based biosensor for the detection of interleukin-6 in human serum, saliva and sweat on a nanoporous membrane using non-faradaic electrochemical impedance spectroscopy.
(Invited) Soft Electronic Devices for Noninvasive Health Monitoring: From the Skin to the Deep Tissues
Authors: Xu Sheng
Published: February 2020

Soft electronic devices that are capable of acquiring multichannel human body physiological signals noninvasively represent an important trend for healthcare monitoring. Combined strategies of materials design and advanced microfabrication on the system level present unique opportunities. In this presentation, I will discuss a rationally designed “island-bridge” matrix that allows hybridizing general classes of materials with soft substrates. Specifically, the hard components are integrated on the predefined distributed islands, and the wavy bridges will deform to absorb the externally applied stress. The results are fully functional systems that are rigid locally in the islands, but soft globally that places minimal constraint on the human body. Demonstrated prototypes include a multichannel health monitor that can sense local field potentials, temperature, strain, acceleration, and blood pressure in central arteries and veins. Integrate radios allow wirelessly transmitting the acquired data to the backend receiver. This platform technology holds profound implications for integrating a broad range of sensors, actuators, and circuit components, for monitoring, diagnosing, and even treating a broad range of health conditions.
(Invited) Two-Dimensional Materials for Wearable Electronics
Authors: Gao Wei
Published: February 2020

The term “smart-clothes” has been applied over the past few years referring to the attachment of commercial (rigid) electronic devices to an article of clothing with applications mostly in performance sports or futuristic fashion shows. An actual smart fabric comprising the seamless integration of soft (flexible) electronics within the textile itself is still mainly in the R&D stages at prohibitively high manufacturing costs.

Two-dimensional materials, such as graphene and Mxene, have demonstrated attractive electrical and electrochemical properties for flexible electronic applications. However, their direct incorporation into textile structures for truly "wearable" applications have rarely been investigated or demonstrated. In this talk, we will introduce the recent progress of our research group on relevant topics, namely 1) 2D-material based hybrid yarns as supercapacitors via industrialized wet-spinning processes, and 2) wearable microsupercapacitors on various textile structures (PET or Cotton fabrics, and PP or nylon nonwovens) with good washfastness and high flexibility. We will focus on the fundamental aspects and major technological obstacles of the integration of novel functional materials with traditional textile processings and products.
(Invited) Fully Formed Reverse Fabrication Techniques for Flexible Electronics
Authors: Yu Ki Jun
Published: February 2020

Recent progress in the development of the flexible and stretchable systems with various materials strategies establishes a fundamental basis for a high-performance electronics on the soft and ultrathin bendable elastomeric deformable substrates. The resulting enabled type of functionality cannot be reproduced using conventional wafer-based technologies. These types of electronics on the unusual soft substrates relies on the techniques of either top-down approaches or bottom-up approaches. These approaches allow assemblies of ultra-thin electronics onto various curvilinear shapes, with linear elastic mechanical responses to large strain deformations. However, such electronic devices fabricated using these techniques suffers from the poor device performances compared to that of the conventional rigid substrate based electronics. Here, we report a new technology in flexible electronics based on a new fabrication technique called, “Fully Formed Reverse Device Fabrication.” The key fabrication strategies and examples of various device characteristic allow integration of high-performance electronics with ultra-thin flexible substrates.
Earth Abundant Transition-Metal Based High Entropy Alloys (HEAs) Nanorod Arrays Prepared By Glancing Angle Deposition System (GLAD) Toward High Performance Electrocatalysts for Water Oxidation Reaction
Authors: Wu Shu-Chi , Tseng Ko-Kai , Ai Yuanfei , Wang Kuangye , Manikandan Arumugam , Chen Yu-Ze , Chen Hsuan-Chu , Yeh Jien-Wei , Chueh Yu-Lun
Published: February 2020

High-entropy alloys (HEAs) have recently aroused increasing research enthusiasm due to their attractive properties, such as easy formation of nano-size precipitates, high hardness, good fatigue with fracture resistance, good thermal stability, excellent corrosion resistance and tendency to form simple solid solutions with face-centered cubic (FCC) and body-centered cubic (BCC) crystal structure. However, to the best of our knowledge, the growth of HEAs nanostructures and its electrocatalytic properties have not yet been reported. Herein, we demonstrate for the first time, HEAs nanorod arrays on stainless steel by glancing angle deposition system (GLAD) as electrocatalysts for oxygen evolution reaction (OER). This electrocatalysts exhibited excellent OER activity and durability. Specifically, a low overpotential of 302 mV can be achieved at a current density of 10 mA cm−2, yielding a Tafel slope of ~28 mV dec-1 in 1 M KOH. Moreover, it can be operated more than 500 cycles of a linear voltammetry (LSV) scan at a scan rate of 5 mV/s. The outstanding performances is attributed to the high surface area of nanorod arrays. This work opens up new great potential in the field of energy based application such as batteries, supercapacitors, and electrocatalytic applications.
(Invited) Plant Wearable for Enhanced Agricultural Productivity
Authors: Nassar Joanna M , Khan Sherjeel M , Nour Maha , Almuslem Amani , Hussain Muhammad M.
Published: February 2020

With increased global population, it is important to ensure their basic need: food. While eighty percent of the world's population depend on five agricultural products: rice, wheat, corn, barley, sugar cane, only in 20% areas they can be grown. Often, due to uncertain climatic condition, soil condition, excessive rain, and other natural uncertainties, the agricultural productivity is compromised and often not optimally controlled. Although, with digitization, this unfortunate situation is changing, due to high price, need for constant seamless connectivity and precision and fast data analytics, such digitization is not proliferating at the rate it is required. Finally, naturally most plants have different "skins", shapes, sizes and sensitivities. Here we show, low-cost, standalone, seamlessly connected plant wearable which can conform to sensitive plant sides and can monitor the surrounding micro-climate and plants botanical condition. We use heterogeneous integration of hybrid materials, devices and processes to achieve such ultra-light weight and low-cost disposable systems which potentially change our perspective about traditional ICs and their integration in our daily life.

Figure 1
Applying Battery Tuning Method on Metal Oxide for Highly Selective CO2 Reduction
Authors: Jiang Kun , Wang Haotian
Published: February 2020

Engineering active grain boundaries (GBs) in oxide-derived (OD) electrocatalysts is critical to improve the selectivity in CO2 reduction reaction (CO2RR), which is becoming an increasingly important pathway for renewable energy storage and usage. Different from traditional in situ electrochemical reduction under CO2RR conditions, where some metal oxides are converted into active metallic phases but with decreased GB densities, here we introduce the Li electrochemical tuning (LiET) method to controllably reduce the oxide precursors into interconnected ultrasmall metal nanoparticles with enriched GBs.

By using ZnO as a case study,1 we demonstrate that the LiET-Zn with freshly exposed GBs exhibits a CO2-to-CO partial current of ∼23 mA cm–2 at an overpotential of −948 mV, representing a 5-fold improvement from the OD-Zn with GBs eliminated during the in situ electro-reduction process. Another representative study is on Cu2O,2 we report the tuning of facet exposure on Cu foil through battery cycling which gives a 6-fold improvement in C2+ to C1 product ratio as compared to polished Cu foil with a maxima C2+ Faradaic efficiency over 60 % and H2 below 20 %. Detailed mechanism study is carried out using density functional theory calculations to shed light on the energetics of the initial C-C coupling steps, while dynamic catalyst surface structure evolution and relevant reactive intermediates are monitored by in situ spectroelectrochemical techniques including Raman scattering and surface enhanced IR spectroscopy.

References:

(1) Jiang, K., Wang, H., Cai, W.B. & Wang, H. ACS Nano
11, 6451-6458 (2017).

(2) Jiang, K., Sandberg, R.B., Akey, A.J., Liu, X., Bell, D.C., Nørskov, J.K., Chan, K. & Wang, H. Nat. Catal. in press (2018).
The Effect of Membrane and Catalyst for Cell Polarization of PEM Water Electrolysis
Authors: Ban Hee-Jung , Kim Min-Young , Kim Yoong-Ahm , Kim Ho-Sung
Published: February 2020

Commercial proton ion exchange membranes (Nafion 117, Dufont, USA) are generally supplied in the form of Na+ to storage. Pretreatment accelerate the ionic conductivity of membrane by converting the surface of the membrane into the functional group (-SO3H) having the form of proton ion. The pretreatment process may cause a significant increase in the total cost of water electrolysis and sometimes the expected results, i.e. reduction of membrane fouling, may not be achieved. In this study, we investigated the electrochemical characteristics of MEA according to the treatment condition of membrane and the type of catalyst such as Iridium black and Iridium oxide. Electrochemical and surface morphology of MEA were studied by I-V curves, electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM).
Effect of Alloying on Electrodeposited Ni Electrocatalyst for Oxygen Evolution Reaction
Authors: Kim Jae Jeong , Kim Byung Keun , Kim Soo-Kil , Cho Sung Ki
Published: February 2020

Since the global energy demand shows rapid expansion from last several decades, coping with serious environmental pollution and searching for renewable energy sources have been the pan-international problems. Among the various renewable energy sources, hydrogen is considered as a noticeable candidate, since hydrogen combustion does not discharge any air-pollutant.

There are still many obstacles for hydrogen to alternate the existing fuels, however, mainly due to its difficulties in large-scale production. Indebted with this, electrochemical water splitting attracted a great attention since it shows excellent efficiency to obtain hydrogen from water. Among the all sorts of electrocatalysts, iridium oxide and ruthenium oxide are ranked as the uppermost standard for the oxygen evolution reaction (OER). These catalysts have ultimate disadvantages; nevertheless, extremely high prices limit their usage on the mass production of hydrogen.

Recently, many researches were focused on transition-metal-based catalysts because of their low cost, good stability and high catalytic activity on OER. Not only transition metals, but also many derivatives such as phosphorous-alloy-based have been suggested. These alloy catalysts often deliver higher catalytic activity than separated single-metal-based ones, due to synergetic effects induced by transition of valence state and enhanced electrical conductivity.

In this study, we discovered the effect of alloying another element on the Ni OER catalyst. Phosphorous, which is known as good alloying element for improvement of OER activity, was directly incorporated via electrodeposition method. Electroplating enables facile synthesis of the electrocatalyst layer in wet condition without any high temperature process. Furthermore, we introduced Cu as another alloying element and confirmed its catalytic behavior toward OER, compared to conventional Ni phosphorous electrocatalyst.
Degradation of IrOx Nanoparticles Supported Onto Sb-Doped SnO2 Aerogel Monitored By Dynamic Electrochemical Impedance Spectroscopy and Identical-Location TEM
Authors: Claudel Fabien , Dubau Laetitia , Sunde Svein , Ozouf Guillaume , Beauger Christian , Piccolo Laurent , Maillard Frederic
Published: February 2020

Supporting metal nanoparticles is a common approach in heterogeneous gas-phase catalysis to decrease the metal loading, prevent agglomeration and thus minimize the cost of a catalytic conversion. This approach proved particularly successful in proton-exchange membrane fuel cells (PEMFC) where the replacement of Pt-blacks (used in early PEMFCs) by carbon-supported Pt nanoparticles has significantly improved the Pt specific power density. Using the same material’s concepts in proton-exchange membrane water electrolysers (PEMWE) could minimize the noble metal loading especially at the anode where the oxygen evolution reaction (OER) takes place. However, high-surface area carbon supports are rapidly degraded in the operating conditions of a PEMWE anode (E > 1.6 V vs. the reversible hydrogen electrode, T = 80 °C) calling for alternative support materials. In this contribution, IrOx nanoparticles were synthesized using the polyol method and deposited onto antimony doped tin dioxide aerogel (ATO) or Vulcan XC-72 (as a reference), and tested as OER electrocatalysts. By combining classical electrochemical techniques, dynamic Electrochemical Impedance Spectroscopy (dEIS) and Identical-Location Transmission Electron Microscopy (IL-TEM), we gained some insights into the mechanisms leading to loss of OER activity. IL-TEM images (Figure 1) provide strong evidence that the activation step was detrimental to the ATO support while no major degradation was observed at higher voltages (OER region). Approximately 73 % of the initial activity was lost for IrOx/ Vulcan XC-72 after 4,000 potential cycles between 1.2 and 1.6 V vs. the reversible hydrogen electrode (RHE) compared to 16 % for IrOx/ATO. The polarization resistance measured in the OER region by dEIS remains roughly the same for IrOx/ATO while a large increase was observed for IrOx/Vulcan XC-72.

Figure 1
Amorphous Cobalt Phyllosilicate with Layered Crystalline Motifs As Water Oxidation Catalyst
Authors: Kang Kisuk , Kim Ju Seong , Park Inchul , Jeong eun-Suk , Jin Kyoungsuk , Seong won Mo , Yoon Gabin , Kim Hyunah , Kim Byounghoon
Published: February 2020

The development of a high-performance oxygen evolution reaction (OER) catalyst is pivotal for the practical realization of a water-splitting system. Although an extensive search for OER catalysts has been performed in the past decades, cost-effective catalysts remain elusive. Herein, an amorphous cobalt phyllosilicate (ACP) with layered crystalline motif prepared by a roomtemperature precipitation is introduced as a new OER catalyst; this material exhibits a remarkably low overpotential (η ≈ 367 mV for a current density of 10 mA cm−2). A structural investigation using X-ray absorption spectroscopy reveals that the amorphous structure contains layered motifs similar to the structure of CoOOH, which is demonstrated to be responsible for the OER catalysis based on density functional theory calculations. However, the calculations also reveal that the local environment of the active site in the layered

crystalline motif in the ACP is significantly modulated by the silicate, leading to a substantial reduction of η of the OER compared with that of CoOOH. This work proposes amorphous phyllosilicates as a new group of efficient OER catalysts and suggests that tuning of the catalytic activity by introducing redox-inert groups may be a new unexplored avenue for the design of novel high-performance catalysts.
(Invited) Active and Stable Metal Supported Thin Film Metal (Hydroxy-) Oxides for Oxygen Reduction/Evolution Reactions
Authors: Back Seoin , Siahrostami Samira , Nørskov Jens
Published: February 2020

A successful commercialization of fuel cell and water electrolyzer is currently limited by a lack of cost-effective and highly active electrocatalysts for a cathode reaction (oxygen reduction reaction, ORR) in fuel cells and anode reaction (oxygen evolution reaction, OER) in water electrolyzer, respectively. As a promising catalyst candidate for electrochemical reactions, partially oxidized ultrathin metal film supported on transition metal substrates have been investigated recently. Previous theoretical results by Greeley et al.1 showed that partially oxidized metals can be stabilized by the presence of metal substrates, altering the stability of metal (hydroxyl-)oxide compared to the bulk counterparts. They also applied metal-supported thin films toward alkaline hydrogen evolution reaction, and calculations demonstrated its high potential to lower the reaction kinetic barriers.

In this talk, I will discuss the stability of various thin film metal (hydroxy-) oxides on various metal substrates. Cost-effective metal (hydroxy-) oxides on four face centered cubic (fcc) metal supports were considered. The density functional theory results show that most of metal (hydroxy-) oxide thin films are stabilized on metal supports (up to 1.5 eV per formula unit), implying a possibility of metal-supported thin films to survive in ORR/OER conditions. I will also discuss the applicability of these materials as ORR/OER catalysts.

1Z. Zeng, K. Chang, J. Kubal, N. Markovic and J. Greeley, Nature Energy
2, Article number: 17070 (2017)
Facile Deposition of Transition Metal Phosphides into Mesoprous Carbon: Iron’s Role in Oxygen Evolution Catalysis
Authors: Leonard Daniel Philip , Stickle William F. , Ji Xiulei
Published: February 2020

Alkaline water splitting has long been seen as a potential source of renewable hydrogen. However, the sluggish kinetics of the oxygen evolution reaction (OER) limits efficiency of such systems. Herein we report on a simple, general method for the deposition of transition metal oxides into mesoporous carbon carbon substrates and their conversion to highly active transition metal phosphides (TMP). We investigated the activity of these catalyst constructs in the presence and absence of iron impurities. The highest activity catalyst requiring an overpotential of 310 mV and a Tafel slope of 42mV/dec was our iron phosphide catalyst. We also show that the activity of the TMP construct is directly related to the presence of iron either in the catalyst itself, or as an impurity in the electrolyte.
Engineering Surface-Binder Interactions in High Energy Density Nanowire Conversion Electrodes for Improved Cycle Life without Fluorinated Additives
Authors: Pandres Elena P. , Olson Jarred Z. , Schlenker Cody W. , Holmberg Vincent C.
Published: February 2020

High capacity conversion electrode materials – like silicon and germanium – that undergo a large volume change upon lithiation and delithiation, require the formation of a robust solid-electrolyte interphase (SEI) layer, which is critically important to mitigate deleterious irreversible reactions that occur at the electrode-electrolyte interface. Over time, these irreversible reactions at the electrode surface result in capacity fade by decreasing the number of mobile lithium ions within the cell and by creating a more hindered diffusion path for lithium ions as they travel toward the electrode. To combat the recurrence of these irreversible reactions in high-capacity conversion electrode systems, the addition of electrolyte additives, such as fluoroethylene carbonate (FEC), is typically deemed necessary to promote stable cycling and improve capacity retention. The observed improvements associated with the inclusion of these virtually universally employed additives have been previously attributed to fluorinated reductive decomposition products that enable the formation of a robust SEI layer.

Clearly, careful control over interfacial chemistry and surface reactions are critical for the design of robust electrochemical systems; however, the surface chemistry of the active material is typically ignored prior to electrode formulation. In most studies of high capacity conversion electrode materials, the surfaces remained unmodified, and the active material is incorporated irrespective of what uncontrolled – potentially oxidized – surfaces happen to be present in the native state. Herein, we systematically investigate the electrochemical cycling of germanium nanowire composite conversion electrodes with controlled surface chemistry, formulated with an array of polymeric binders, both in the presence and in the absence of fluorinated electrolyte additives. We observe that controlled modification of the nanowire electrode surface, when paired with certain binders, dramatically improved germanium nanowire-based electrode cycling retention and longevity. In fact, some of these pairings exhibit improved capacity retention in the absence of the fluorinated additives typically deemed necessary for stable cycling, whereas the addition of the fluorinated additive caused the cell capacity to fade more rapidly. Finally, through careful control of surface chemistry and strategic choice of binder material, we show that germanium nanowire-based conversion electrodes can maintain capacity retention in the complete absence of fluorinated additives, fluorinated electrolytes, and fluorinated binders.
Structure and Voltage Recovery Driven by Defects Elimination in Li-Rich Layered Oxide Cathode Materials
Authors: Zhang Minghao , Liu Haodong , Meng Ying Shirley
Published: February 2020

Lithium-ion batteries (LIBs) are ubiquitous in a wide range of technologies, including cell phones, electric vehicles, and energy grid, and are indispensable in the transition toward sustainable energy technology. The battery performance is inherently connected to the capability of lithium ions to reversibly intercalate with the electrodes. The capacity of classical layered transition metal (TM) oxides, the primary commercial cathode materials, is limited to cationic redox activity. Anionic redox has thus emerged as a new paradigm for designing novel cathodes for next generation LIBs. It is recently confirmed oxygen redox in lithium-rich layered oxides (LRLO) with composition xLi2MnO3∙(1-x)LiTMO2, which enables this group of materials exhibit reversible capacities exceeding 280 mAh g-1.

Unfortunately, this material undergoes voltage fading and instability that is rooted in irreversible structural transformation in terms of defects formation including lithium and oxygen vacancies, lithium tetrahedron, TM migration, edge dislocations, stacking fault, and local strain. Modification methods including morphology control, composition gradient, surface treatment, foreign elements doping, etc., have been proposed in the literatures to mitigate the defects formation and maintain the structure reversibility. Despite their improvement, the intrinsic voltage fading is still inevitable and remains a challenge that will require considerable effort to overcome.

In this work, we demonstrate a path to recover the layer structure and working voltage through high-temperature annealing. The treatment at high temperature recovers the local Li-excess environments around oxygen, oxygen stacking sequence, and eliminates microstrain associated with different defects. As a result, the voltage profile once more shows plateau region during charge and the average discharge voltage is restored of the cycled cathode after heat treatment. Both theoretical calculations and experimental characterizations illustrate the mechanisms underlying the heating induced recovery. The structure metastability and defects removal are decisive in structure and voltage recovery of LRLO cathode material.
(A03 Best Poster Winner) In Situ Study of the Reaction Mechanisms of Tmspi and Tmspa Additives in Lithium Ion Batteries By Online Electrochemical Mass Spectrometry
Authors: Bolli Christoph , Guéguen Aurélie , Mendez Manuel , Berg Erik J.
Published: February 2020

Electrolytes in modern lithium ion batteries (LIBs) mostly consist of a mixture of a linear and a cyclic organic carbonate, a conducting salt and several electrolyte additives. The latter fulfill a variety of different roles in LIBs. They are for example used to form a more stable SEI on the anode, they can act as flame retardant or redox shuttle to improve the safety of the battery, they can be used as sacrificial components which are oxidized at high cell voltages before the regular electrolyte and they can be applied to scavenge molecules which are detrimental to performance of LIBs, such as HF.(1)

Tristrimethylsilylphosphite (TMSPi) and Tristrimethylsilylphosphate (TMSPa) have gained increasing interest as electrolyte additives in recent years. Both are known to improve the performance of LIBs and it was shown that both act as HF scavengers.(2) However, also other roles such as their oxidation and formation of a protective interphase on the cathode (3) or the complexation of transition metals on the surface of the cathode (4) have been described.

Online electrochemical mass spectrometry (OEMS) was previously shown to be a valuable tool to monitor the gas evolution in LIBs. It allows to study processes in the electrolyte such as solvent decomposition processes (5) or the hydrolysis of the conducting salt,(6) as well gas release resulting from structural changes in the active material as shown for the surface reconstruction of Ni-rich NCM cathodes(7).

In this contribution the effect of TMSPa and TMSPi on the gassing of HENCM/graphite full cells as well as cells with carbon model electrodes is presented. According to our results, the formation of a protective surface layer or complexation of surface transition metal centers are secondary effects in these systems, we rather show that these TMS based compounds act mainly as scavenging agents for harmful reaction intermediates such as HF and LiF. This leads to increased electrolyte stability and improved cycling performance.

(1) A. M. Haregewoin, A. S. Wotango, B.-J. Hwang, Energ. Environ. Sci. 9, 1955-1988 (2016).

(2) J.-G. Han, S. J. Lee, J. Lee, J.-S. Kim, K. T. Lee, N.-S. Choi, ACS Appl. Mater. Interfaces 7, 8319−8329 (2015).

(3) S. Mai, M. Xu, X. Liao, J. Hu, H. Lin, L. Xing, Y. Liao, X. Li, W. Li, Electrochim. Acta 147, 565-571 (2014).

(4) C. Peebles, R. Sahore, J. A. Gilbert, J. C. Garcia, A. Tornheim, J. Bareño, H. Iddir, C. Liao, D. P. Abraham, J. Electrochem. Soc. 164, A1579-A1586 (2017).

(5) D. Streich, A. Guéguen, M. Mendez, F. Chesneau, P. Novák, E. J. Berg, J. Electrochem. Soc. 163, A964-A970 (2016).

(6) A. Guéguen, D. Streich, M. He, M. Mendez, F. F. Chesneau, P. Novák, E. J. Berg, J. Electrochem. Soc. 163 A1095-A1100 (2016).

(7) D. Streich, C. Erk, A. Guéguen, P. Müller, F. Chesneau, E. J. Berg, J. Phys. Chem. C 121, 13481-13486 (2017).
Towards Finding Cathode Materials for Aluminum Batteries: Kinetics and Thermodynamics of Al Ion Intercalation into Mxenes
Authors: VahidMohammadi Armin , Beidaghi Majid
Published: February 2020

Batteries based on multivalent ions such as Mg2+, Ca2+, and Al3+ can be cheaper and safer alternatives to Lithium-ion batteries (LIBs). However, the development of multivalent-ion batteries has been hindered by the lack of appropriate electrolytes and cathode materials for these new battery chemistries. Understanding the kinetics and thermodynamics of multivalent ion intercalation into structure of materials is essential for designing cathode materials for these systems. Recently, we have reported on high-performance cathode materials for rechargeable aluminum batteries based on two-dimensional (2D) vanadium carbide MXene (V2C).[1] MXenes are a family of 2D transition metal carbides, nitrides, and/or carbonitrides with a general formula of Mn+1Xn (n=1,2, and 3, M is a transition metal, and X is carbon and/or nitrogen), that are produced by selective etching of the A layer elements (i.e. Al) from MAX phases (i.e. V2AlC), a large group of layered ternary carbides, nitrides, and carbonitrides.[2] In this presentation, we report our recent findings on kinetics and thermodynamics of Al ion intercalation into MXenes. Using various electroanalytical and spectroscopic techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), galvanostatic intermittent titration technique (GITT) and electrochemical impedance spectroscopy (EIS) we have shed light on the intercalation mechanism and kinetics of intercalation of Al ions into MXene structures. Our results show that interlayer expansion of MXenes can significantly decrease the diffusion coefficient of ions and improve their performance of the cathode materials. These findings can potentially lead to development of a group of cathode materials for high performance Al-batteries

References

VahidMohammadi, A. Hadjikhani, S. Shahbazmohamadi, and M. Beidaghi, Two-Dimensional Vanadium Carbide (MXene) as a High-Capacity Cathode Material for Rechargeable Aluminum Batteries, ACS Nano, 2017, 10.1021/acsnano.7b05350.

2D metal carbides and nitrides (MXenes) for energy storage, B. Anasori, M. R. Lukatskaya, and Y. Gogotsi, Nature Energy, 2017, 10.1038/natrevmats.2016.98.
Electrochemical Performance of Dry Battery Electrode
Authors: Shin Joon , Duong Hieu
Published: February 2020

Li ion battery has been a key research and development topic in energy storage industry in past decade because of considerable consumer demand and market growth including consumer electronics and transportation. A significant effort is focused on development of new chemistry of battery materials such as nickel-rich layered cathode and high capacity silicon anode.

Unlike recently reported solvent-free electrode manufacturing variants such as electrostatic spray coating1, dry powder painting2 and isothermal hot-pressing3, Maxwell Technologies unique heritage solvent-free dry electrode process4 used to commercialized Ultracapacitor electrodes can be adapted to existing lithium ion battery chemistries and advanced materials. Maxwell dry electrode manufacturing demonstrative benefits over conventional slurry wet coating process includes, (i)environmentally benign due to elimination of toxic solvent, (ii) lower cost by reducing capital and operating expenditures, resulting from elimination of solvent recovery and recycling system, (iii) improved energy and power density afforded by unique dense high loading electrode microstructures.

Maxwell Technologies has applied its proprietary dry electrode process to produced lithium ion battery cathode and anode electrode with unparalleled energy density and enhance cycle life over conventional wet coated electrodes. We have demonstrated dry robust process capability, incorporating current and advanced chemistries such as graphite, silicon, metal alloy, and nickel-rich layered transition metal oxides. In addition, we have demonstrated roll-to-roll dry process scalability using common and advanced battery material chemistries.

This paper presents physical properties of self-supporting dry electrode film and electrochemical performance of dry battery electrode in half cell and full cell. We will share electrochemical performance of dry battery electrode produced at the lab-level and pilot-level in single layer pouch cell as well as multilayer stacked pouch cell platform with capacity raging from about 200mAh to about 15Ah.

References:

Al-Shroofy, M.; Zhang, Q.; Xu, J.; Chen, T. Kaur, A.P.; Cheng, Y., J. Power Sources, 2017, 352, 187-193

Ludwig, B.; Zheng, Z.; Shou, W.; Wang, Y.; Pan, H., Scientific Reports, 2016, 1-10

Park, D., Ca~nas, N.A.; Wagner, N.; Friedrich, K.A., J. Power Sources, 2016, 306, 758-763

Duong, H.; Suszko, A.; Feigenbaum, H., 229th ECS meeting, May 29-June 6, 2016, Abstr. #475