bluuebunny/crossref_metadata_2025 huggingface dataset:
(Invited) Nanogap Voltammetry of Clean Surface of Electron-Beam-Deposited Carbon
Authors: Amemiya Shigeru , Chen Ran , Najarian Amin , Balla Ryan , McCreery Richard Louis
Published: February 2020

Clean surfaces of conducting carbon materials are highly demanded for fundamental and applied electrochemistry to mechanistically understand and practically utilize their intrinsic reactivity. In this presentation, we will discuss about the nanoelectrochemical characterization of clean carbon surfaces to gain novel insights into heterogeneous electron-transfer (ET) mechanism with broad implications beyond carbon electrochemistry. Electron-beam deposited carbon (eC) is formed in high vacuum (<6 µtorr) and protected from adventitious contamination by a washable KCl layer deposited without breaking vacuum. Fast ET kinetics of exceedingly flat, clean eC surfaces is reliably measured in ultrapure water using nanogap voltammetry based on scanning electrochemical microscopy and compared quantitatively with Marcus and Frumkin theories. An outer-sphere ET mechanism, which is typically only presumed, is evidenced experimentally for (ferrocenylmethyl)trimethylammonium and tris(1,10-phenanthroline)cobalt(II) (Co(phen)3
2+) by excluding an inner-sphere mechanism. Indeed, the oxidation of Co(phen)3
2+ agrees unprecedentedly well with Marcus theory of adiabatic outer-sphere kinetics in comparison to any redox couple on carbon or metal electrodes reported previously. The coupled reduction of Co(phen)3
3+ deviates from Marcus theory to reveal a unique double-layer effect caused by the adsorption of a redox molecule itself, i.e. Co(phen)3
2+, which contrasts to the Frumkin effect based on the adsorption of inert electrolytes. Remarkably, the Ru(NH3)6
3+/2+ couple exceeds adiabatic limits not only at eC, but also at other carbons and metals, which we attribute to faster inner-sphere ET of adsorbed forms of this couple. In contrast, an inner-sphere pathway is not mediated by the adsorbed Fe(CN)6
3–/4– couple, which dramatically self-decelerates the outer-sphere pathway through a double-layer effect.
Automated and High-Throughput Reactive Accelerated Aging System to Evaluate Performance of Neural Implants
Authors: Street Matthew Grant , Caldwell Ryan , Warren David J. , Rieth Loren , Takmakov Pavel A
Published: February 2020

Explosive growth of therapeutic applications for neuromodulation is partly associated with miniaturization of neural implants. Miniaturization is implemented with novel fabrication techniques and novel materials that do not have a proven history of clinical use. Pilot clinical studies with these novel devices demonstrated that failure of the implants in the body and their poor lifetime presents a major bottleneck for this technology. Lifetime evaluation of different neural implants in animal models requires very long endpoints to establish their viability on clinically relevant timescales. To accelerate testing of innovative materials and potentially replace chronic animal testing, we developed reactive accelerated aging (RAA) that uses reactive oxygen species to simulate foreign body response. The first version of the RAA system accurately represented degradation mechanisms of these devices, but required daily monitoring and maintenance and experienced some variability in performance. To address these issues, we developed a new system that implements automation, modularity and multiplexing. First, we designed the RAA system to be scalable and modular to facilitate multiplexing for high-throughput testing. Second, we replaced the thermostats with mineral oil thermal transfer with electrical heating. Third, we implemented automatic control of hydrogen peroxide concentration using an in-line UV spectrophotometer. Fourth, through using a Raspberry Pi we are able to perform in situ optimization of operating parameters and increased control of the system. These improvements will enable us to perform experiments in parallel for a high-throughput approach to investigating optimal test conditions for different materials or device geometries. Lastly, we implemented automatic sampling and analysis of leachable compounds to establish and quantify neural implants failure modes. Through these improvements, we developed a cost-effective tool for rapid evaluation of durability of neural implants in vitro and provide the framework to improve the functional lifespan of these devices. Studies performed using this technique to rapidly age cortical implants has been compared to those performed in vivo in a feline model performed at University of Utah. Results of this comparison using scanning electron microscopy characterization show similarities between aging implants for 7 days in vitro (RAA) to aging implants for over 3 years in vivo (feline).
UV Coating Processes to Enhance Li Ion Battery Performance and Reduce Costs
Authors: Arnold John R , Voelker Gary
Published: February 2020

UV Curing is a process used in many industries to improve manufacturing reliability, minimize or eliminate solvents, reduce costs, and to achieve dramatic production increases. This presentation demonstrates performance of UV products and processes developed specifically for Lithium Ion Batteries. UV processes are a natural for coating separators. Examples will demonstrate three types of separator coatings designed to improve battery safety: ceramic coatings, shut down coatings, and grab coatings. UV products have also been developed for electrode coatings. Cathode coatings can be made without NMP. Electrochemical performance is demonstrated for coatings with coatings in the following composition range: 90-5-5, 90-7-3, 98.5-0.5-1 (NMC-C-UV binder).
Electrodeposition of Carbon from High Temperature Carbonate Melts
Authors: Hughes Matthew , Allen Jessica A , Donne Scott W
Published: February 2020

The storage and release of electrical energy is vital to the functioning of many necessities of modern life including portable electronic devices, power tools, and automobiles. In the face of our ever-increasing need for better energy storage devices, it is desirable that we continue to investigate superior materials for use in battery and supercapacitor devices. It has long been known that carbons may be produced through the electrolytic reduction of molten carbonates, with the mechanism of this reduction being thought to proceed by way of Eqn 1 [1], i.e.;

CO3
2- + 4e- ---> C+3O2- …(1)

For this research carbons were prepared by varying the electrodeposition parameters around a standard set of conditions (Li2CO3-Na2CO3-K2CO3 electrolyte, 0.25 A/cm2 current density, graphite substrate, 600°C). The research of this group indicates at this point that there exist reproducible patterns in the properties of our carbons based on most of these variables, with the primary result of the research linking decreased current densities, decreased temperatures, and every electrolyte except Li2CO3-Na2CO3, but not substrate to any major degree, to increased capacitive performance.

1. Le Van, K., et al., Electrochemical formation of carbon nano-powders with various porosities in molten alkali carbonates. Electrochimica Acta, 2009. 54(19): p. 4566-4573.
Influence of Calcination Treatments on the Formation of N-Doped Carbon Nanofibers and Their Electrochemical Properties
Authors: Ojeda-López Reyna , Ramos-Sánchez Guadalupe , Esparza-Schulz Juan Marcos , Pérez-Hermosillo Isaac Jhonnatan , Domínguez-Ortiz Armando , González I.
Published: February 2020

Carbon nanofibers (CNFs) are materials with potential applications as electrode supports for fuel cells, mainly due to their interesting characteristics: i) high surface area, ii) controlled chemical properties, and iii) high electric conductivity. CNFs can be modified by nitrogen doping; this procedure allows the formation of specific sites on the nanofibers surface which, when used as support, lead to controlled size and dispersion of the active material; moreover, the presence of N atoms as dopant causes the modification of the electronic density close to the doping site, specially diminishing the electron density in neighboring C atoms which also catalyze the fuel cell reactions.

In this work we propose a different alternative, the production of the support with the intrinsic formation of dopants in CNFs. N-doped carbon nanofibers were synthetized by electrospinning of polyacrylonitrile (PAN) followed by a two-step calcination process: stabilization and carbonization, the first was carried out under air atmosphere at 553 K while carbonization was conducted in inert atmosphere at five different temperatures, 873, 973, 1073, 1173 and 1273 K. X-ray Photoelectron spectroscopy experiments indicate that depending on the carbonization temperature this process produces different amounts of nitrogen species in the materials. For carbonization temperatures of 873 and 973 K, nitrogen species are mainly found in N-6 form (piridinic) while a small amount of nitrile groups is still present. For the materials with temperature treatment above 1073 K, N-Q (quaternary or graphitic nitrogen) becomes the most abundant nitrogen species, this indicate than the formed N-Q is much more stable than N-6 at higher temperatures.

The stability of the material was evaluated by cyclic voltammetry in acid media in anodic direction. The results indicate that all CNFs present a less positive oxidation onset potential in comparison to carbon Vulcan. This result agrees with thermogravimetric analysis in which N doped CNF decomposition (CO2 formation) is obtained at higher temperatures than commercial supports. Moreover, the CNFs were also evaluated as electrocatalysts for the oxygen reduction reaction (ORR) in alkaline conditions. The preliminary results show that as the quantity of N-Q augments, the catalytic activity concomitantly increases as well, i.e. the onset potential for oxygen reduction increases.
Imaging Space Charge Regions in Sm-Doped Ceria Using Strain-Based Scanning Probe Techniques
Authors: Adler Stuart B. , Gerwe Brian S , Esfahani Ehsan N , Wang Peiqi , Chen Qian Nataly , Li Jiangyu
Published: February 2020

Scanning probe methods have long been employed to conduct local electrochemistry. However, connecting these measurements to macroscopic electrochemical performance of an electrode can be challenging. Workers have recently begun exploring strain-based methods sensitive to local defect concentrations in materials. These include electrochemical strain microscopy (ESM) and more recently scanning thermo-ionic microscopy (STIM). The basis for these techniques will be discussed, with examples involving Li battery materials and the study of grain boundaries in rare-earth doped ceria. Also discussed will be the possible application of these techniques as local witnesses of defect concentrations in complex electrode structures during impedance or other transient measurements.
Measurement and Numerical Simulation of Temperature Distributions of a Micro-Tubular SOEC during H2O/CO2 Co-Electrolysis
Authors: Maeda Atsushi , Watanabe Kentaro , Araki Takuto , Mori Masashi
Published: February 2020

Power to gas(PtG) has been payed attention as one of the ways to promote introduction of renewable energy. Solid oxide electrolysis cells(SOECs) are one of the electrolysis devices in the PtG. Because of its low electrolysis voltage and high utilization of generated heat, SOECs are expected to be the most attractive electrolysis cell from the viewpoint of energy conversion efficiency. In addition, since SOECs can electrolyze CO2 into CO, which is used as a raw material of alkane, it attracts attention as technique of the recycling of CO2. Thus, in recent years there has been growing interest in developing a co-electrolysis system. Because SOECs are constructed mainly on brittleness ceramics, a detailed understanding of temperature distribution in the cell is important for reducing thermal stress. Although the electrolysis reaction is endothermic, overpotentials and electrical resistivity of cell are factors of heat generation in the cell. Thus, the temperature distribution in SOECs is very complicated.

In this study, the temperature distribution in the micro-tubular cell was measured by thermocouples and a thermal imaging camera. The micro-tubular cell consists of (ZrO2)0.92(Y2O3)0.08 (YSZ)/ YSZ / La0.8Sr0.2MnO3 (LSM). The current collection of air electrode area was performed using Pt paste and wires. During the electrolysis process, the temperature change in the cell was small around gas inlet, and the difference of temperature along a tube length direction to gas outlet increased. Around Pt wire on the surface of the air electrode, the temperature change was maximum. Furthermore, the temperature change around gas outlet increased because of current collector was attached to the edge of fuel electrode at the side of gas outlet. Compared to steam electrolysis, the temperature change during the co-electrolysis process was smaller.
Co-Electrolysis, Quo Vadis?
Authors: Foit Severin Robert , Dittrich Lucy , Vibhu Vaibhav , Vinke Izaak C. , Eichel Rüdiger-Albert , de Haart L.G.J.
Published: February 2020

Co-electrolysis, the electrochemical conversion of steam and carbon dioxide with the use of renewably generated electricity to produce syngas, can be regarded as the enabling step to the sustainable production of synfuels and high-value chemicals. This advantageous method of beneficial CO2-valorization is predetermined to couple energy-intense sectors such as “traffic and transportation” and “chemical industry”. The needed products for these markets presuppose different syngas compositions through their production routes and according to that determine the applied technology of syngas generation by its achievable H2:CO ratio. The concept of high-temperature co-electrolysis offers both an efficient electrochemical conversion and accessibility to H2:CO distributions from 1:1 to 3:1 by a given set of parameters (temperature, current density, material,…). Though, this is yet to be shown as research has been focused on electrochemical analysis of materials, cells and stacks rather than on product distribution depending on operating parameters and an all-embracing quantitative product analysis[1].

Herein, we examine the possibilities and variety on syngas production with focus on (electrochemical) performance and syngas yield and composition under different conditions, e.g. temperature, current density, substrate composition. The experiments were executed on a cathode supported cell (CeramTec) composed of an LSCF anode, a CGO barrier-layer, an 8YSZ electrolyte and a Ni/8YSZ cathode. The testing took place in the temperature range of 750 to 900 °C with preset cell voltages up to 1.4 V. The ratios of water vapor to carbon dioxide have been set to 3:1, 2:1 and 1:1. Furthermore, the cells have been tested with a 50% water – 50% hydrogen mixture for comparison. I/V-measurements and electrochemical impedance spectroscopy have been conducted under the combinations of mentioned conditions. In addition, a full spectrum analysis of the product gases has been performed, i. e. water was not condensed from the product stream prior to the mass spectrometer. Current densities of up to over 1.7 A·cm-2 with polarization resistances of 24 mΩ·cm-2 have been obtained at 900 °C and a cell voltage of 1.4 V with a 9 nl·h-1 flow of 40% water, 40% CO2 and 20% H2 used. I/V-curves decrease in slope and increase in current density with increasing temperature (figure 1). Further investigation is ongoing and the electrochemical performance and efficiency of syngas production will be presented and discussed in detail.

[1] S. Foit, I. C. Vinke, L. G. J. de Haart, R.-A. Eichel, Angewandte Chemie International Edition
2016, DOI: 10.1002/anie.201607552

Figure 1: I/V characteristics of a Ni/YSZ//YSZ//CGO//LSCF single cell during co-electrolysis of different H2/CO2 mixtures in dependence of temperature

Figure 1
Development of an Advanced Flexible Solid Oxide Fuel Cell Stack Concept
Authors: Minh Nguyen
Published: February 2020

An advanced flexible solid oxide fuel cell (SOFC) stack concept with the potential for increased reliability, better performance and lower cost is being developed. This stack concept integrates prime-surface interconnects and single cells into a lightweight and compact structure with reliable gas seals for efficient operation at different temperatures depending on selected materials. The concept has several attractive features icluding reduced stack weight and volume, decreased performance losses in stacking, improved sealing, versatility in incorporation of different types of cell construction (for example, conventional sintered cells or thin-film metal supported cells) and flexibility in gas flow configuration. The prime-surface interconnect is a one-piece metal sheet that incorporates both fuel and oxidant flow fields with peaks o one side of the interconnect serving as flow channels (valleys) on the other side; for exampe, the egg-carton shaped prime-surface flow field. The design of the prime-surface interconnect including the key factors impacting on pressure drop, flow uniformity and formability is being evaluated. Hydroforming has been identified as the forming appoach for prime-surface interconnects. Development of metal-supported cells has been initiated. A fabrication process based on sputtering is being developed for producing cells on metal supports for this stack concept.
Numerical Investigation for 1kW-Class FT-SOFC System to Evaluate the Compact Size Integrated Hotbox Design
Authors: Rashid Kashif , Dong Sang Keun , Mehran Muhammad Taqi
Published: February 2020

In the present work, comprehensive CFD and experiment investigations are performed on the integrated hot box components to determine the optimal operating conditions for 1 kW-class SOFC stack system fueled with natural gas. In the first part, CFD models are implemented on the standalone reformer to make different reformate compositions to determine which composition can provide best stack performance keeping in mind fuel/air utilizations, thermal gradients effect on the stack cells due to internal steam reforming and the parasitic excess air for stack cooling. The parameters that are studied in the simulation includes steam to carbon ratio, the temperature of the reforming tube, effectiveness factors, and methane conversion. The validation and calibration of the numerical model are accomplished through comparison with experiment (also performed on standalone reformer placed in the furnace) reformate compositions and conversion. In the second step, simulations using validated model have also performed on the real-scale integrated hot box components (steam generating tube, reformer, and combustor) to ascertain the performance and effectiveness of this design. Anode and cathode off-gases are burnt in the combustor to provide the necessary energy to execute the methane steam reforming process. The waste heat recovery and compactness due the reformer combustor integration increase the system efficiency. Numerical calculations on different heat exchanger (HX) designs installed around the cells are also performed separately by fixing the boundary conditions obtained from experiments. From the numerical calculations on the full-scale system, it is found that for the SOFC operating temperature of 750°C, combine mole fraction of H2 and CO is ~0.79 for effectiveness factor of 0.02, s/c of 2.5 and methane conversion of 76% which is comparable to the electrically-heated reformer.

Figure 1
Anodic Layers Based on Doped-Ceria/Ni Cermet for Direct Ethanol Fuel Cells
Authors: da Silva Andressa A. A. , Tabuti Francisco N. , Matos Lisiane V. , Steil Marlu C. , Noronha Fabio B. , Fonseca Fabio C
Published: February 2020

Latest generation of solid oxide fuel cells (SOFCs) is a multilayer device in which several functional layers were incorporated to the anode/electrolyte/cathode configuration. Therefore, using an active layer that enables the fuel cell to run using a renewable fuel such as bioethanol is a reasonable strategy. Separating the catalytic and electrochemical reactions in different anodic layers has two main advantages: keeping the high-performance YSZ/Ni cermet and allowing an active and stable catalyst for ethanol reforming. Doped-cerium oxide is an attractive ceramic material for solid oxide fuel cells (SOFCs) because of the excellent electrochemical and catalytic properties and good compatibility with remaining cell components. In the present study, we have investigated the effect of different dopants on the properties of doped-ceria in Ni cermets aiming at using such cermets as the catalyst for ethanol internal reforming in SOFCs. High surface area ceria doped (10 mol%) with Gd, Y, Zr, and Nb were prepared by an hydrothermal method. The ceria-based solid solutions were mixed with Ni by a wet impregnation method to obtain 18 wt.% Ni relative fraction. Such relatively low Ni volume fraction (~15 vol.%) aims at minimizing coke formation while promoting electronic conductivity. The catalyst materials were deposited onto the anode of standard electrolyte-supported cells [(La,Sr)xMnO3 / YSZ / YSZ/Ni] and tested on dry ethanol. The fuel cell tests results were analysed along with data of both steam reforming and decomposition catalytic reactions for ethanol. Post-test analyses evidenced that water electrochemically generatedpromotes ethanol reforming, in agreement with catalytic tests in which doped-ceria/Ni showed no evidence of carbon deposits in the steam reforming reaction. On the other hand, analyses on spent catalysts of ethanol decomposition revealed carbon deposits. Nevertheless, no significant differences were observed for the studied dopants with the notable exception of niobium, which has a limited solubility in the ceria matrix. The experimental results confirm that upon fuel cell operation, ceria-Ni based catalysts promote alcohol steam reforming resulting in stable direct ethanol SOFCs.
Effect of Oxygen Depletion to the Cathode on the Working of Solid Oxide Fuel Cells
Authors: Thambiraj Nelson , Suciu Crina , Waernhus Ivar , Vik Arild , Hoffmann Alex C.
Published: February 2020

During the recent years, SOFC research has mainly been aimed at reducing the capital cost to effectively compete with other power generation technologies. CMR Prototech, Norway is a provider of technical solutions, product designs and tools for various application areas. Currently, CMR Prototech is planning to develop 2 MW modular fuel cell systems for subsea operation. Each module consists of 200 stacks, each stack producing 10kW. In order to address the technical challenges faced during this development and to make SOFC technology feasible for offshore applications more research on fuel cells in marine environment is necessary. This research was aimed at determining the effects of a) reducing partial pressure of oxygen and b) NaCl contamination on the performance of the SOFC cathode of a single SOFC cell. This present paper focuses on the effect of oxygen partial pressure. Single cell tests were performed in a versatile test station, fully automated and controlled using LabVIEW programming. The fluid handling system with mass flow controllers and four-points measurement probes along with field-point connections were installed in the test station. A set of experiments were conducted, reducing the partial pressure of oxygen supplied to the cathode stopwise (at thre relevant temperatures, namely 800, 850 and 900oC). All the cells were characterized and analyzed by I-V curves. The grain structures of the cells were characterized by scanning electron microscopy (SEM) before and after the experiments.
Electrochemical Fabrication of Nanostructured Thin-Film for Renewable Energy Applications
Authors: Yang Yang
Published: February 2020

Freestanding and robust thin-film electrodes are the basis for future renewable energy technology owing to their unique merits: i) additive-free features enable facile fabrication route and long lifetime; ii) can be easily recycled; iii) significant reduce the weight and volume of the energy devices, especially for batteries and supercapacitors; iv) can be integrated into wearable electronic systems. However, previous efforts fail to make significant progress in freestanding metal compound thin-films due to a lack of fundamental understanding and technical breakthrough in freestanding metal compound thin-films. In this work, transformative thin-film nanomanufacturing technology has been developed to fabricate freestanding metal compound thin-films using a facile and scalable electrochemical route. Both experimental and computational studies indicate that a supreme electrochemical performance can be achieved by tuning the microstructure and composition of thin-films. Outstanding energy storage and hydrogen generation properties are therefore obtained by directly using these advanced thin-films as electrodes.
Cost-Effective PEM Electrolysis: The Quest to Achieve Superior Efficiencies with Reduced Investment
Authors: Friedrich Kaspar Andreas , Lettenmeier Philipp , Stiber Svenja , Ansar Asif Syed , Wang Li , Gago Aldo Saul
Published: February 2020

Hydrogen is expected to play an important role as a crosslinking technology between power generation on one hand and transport and industry on the other hand. It can directly replace fossil fuels in transport and industry when produced by water electrolysis with renewable energies such as solar or wind. The relevant technologies are either the mature alkaline electrolysis or the newer proton exchange membrane (PEM) water electrolysis. For PEM electrolysis in particular, key components that determine the stack cost are the titanium-based contact elements, such as the bipolar plates (BPP) and the current collectors (CC), and the high iridium loading of electrocatalyst for the OER in state of art membrane electrode assemblies (MEA). However, the cost structure depends on the specific design of the electrolyser.

This presentation will discuss strategies for cost reduction by synthesizing novel electrocatalyst with the aim of lowering the high Ir loading. Our concept can be applied to supported and alloy electrocatalysts. The supports need to be highly stable and exhibit sufficient electronic conductivity. The enhancement of activity achieved with improved electrocatalyst reaches a factor of about 15 with respect to the best commercially available electrocatalyst.

Additionally, the cost reduction achieved by a titanium coating for stainless steel BPPs or CCs for PEM electrolysis will be discussed. We use vacuum plasma spraying (VPS) to coat either dense coatings for corrosion protection of stainless steel components or build up titanium diffusion layers with defined porosity as contact elements for the MEA. The conductivity of the titanium coating can be improved by well-known Pt or Au additions; however, we have also developed promising non-noble conductivity enhancement elements. Furthermore, the VPS coating and production procedure is adaptable to large-scale industrial production.

Acknowledgements

The research leading to these results has received funding from the European Union’s Seventh Framework Program (FP7/ 2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant n° 621237, “ INSIDE- In -situ Diagnostics in Water Electrolyzers“ and from national projects “LastElSys” and “WESpe” by Federal Ministry for Economic Affairs and Energy.

Figure 1
Nickel Vanadium Layered Double Hydroxides Nanostructures for High-Performance Flexible Supercapacitor Applications
Authors: Tyagi Ankit , Gupta Raju Kumar
Published: February 2020

In recent times, demand for portable electronic devices like mobile phones, cameras and laptops etc. is increasing day by day. Energy storage devices such as batteries and supercapacitors have significant importance because of their high energy density and high power density, respectively.1 Supercapacitor is gaining great amount of attention because it uses less toxic material, offers high power density, excellent electrochemical stability, wide range of operating temperatures and durability. A facile fabrication of low cost, efficient, stable, eco-friendly and earth-abundant electrode materials for supercapacitors is critical.2 Layered double hydroxide (LDH) is new class of material having positively charged hydrotalcite-like layers, weakly bound, intercalating charge compensating anions and water molecules, has showed enormous supercapacitive performance.3 In this work, an ionic lamellar, two-dimensional (2D) nickel-vanadium layered double hydroxide (NiV LDH) nanosheets have been synthesized via facile, cost effective and potentially scalable hydrothermal method. The as-prepared 2D NiV LDH nanosheets coated on Ni foam (NF/NiV LDH) was used as supercapacitor electrode. The electrochemical characterization techniques such as cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS) were used to characterize the material for its electrochemical properties, while SEM, TEM, XRD, BET, and XPS etc. techniques have been used for their morphological, structural and physical characterization. High specific capacitance of ~1581 F g-1 at the current density of 1 A g-1 was observed in three-electrode system using KOH as electrolyte, which remained quite high at increased current density of 10 A g-1. This work demonstrates great potential for NiV LDH nanosheets as electrode material for supercapacitor applications.

References

[1] A. Tyagi, K. M. Tripathi, R. K. Gupta, J. Mater. Chem. A 3, (2015) 22507-22541.

[2] A. Tyagi, R. K. Gupta, Nanomaterials: A guide to fabrication and applications, (CRC Press), 261 (2015).

[3] K. Fan, H. Chen, Y. Ji, H. Huang, P. M. Claesson, Q. Daniel, B. Philippe, H. Rensmo, F. Li, Y. Luo, and L. Sun, Nat. commun. 7 (2016) 11981.
Defect Chemistry and Lithium Transport in ANTI-Perovksite Superionic Conductors
Authors: Ciucci Francesco , Lu Ziheng
Published: February 2020

Solid state electrolyte with fast lithium conduction is the core of the all-solid-state Li battery technology. By substituting the organic electrolyte with a piece of non-flammable ceramic material, we can achieve a better safety, a higher specific capacity and a higher energy density. To date, the major bottle neck for this technology is the slow bulk diffusion of solid state electrolyte and the interfacial incompatibility between the electrolyte and electrodes. To resolve these issues, several families of fast ionic conductors have been developed. The understanding of Li diffusion in these materials is essential to the development of novel family fast ionic conductors. In this sense, atomistic modeling provides us with a unique tool to obtain comprehensive information on the atom motion which is so far hard to access with experimental techniques. In this work, we use density functional theory (DFT) calculations as well as large scale classical molecular dynamics (MD) simulations to simulate the Li diffusion in a novel family of superionic conductor, lithium-rich anti-perovskites and provide an understanding of the Li diffusion behavior.

Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10−3 S cm−1 at room temperature, among the highest reported values to date. We investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using DFT calculations and classical MD simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.
High-Performance Solid-State Battery Enabled By a Stablized Plastic-Crystal Interlayer
Authors: Lu Ziheng , Ciucci Francesco
Published: February 2020

Lithium-ion batteries (LIBs) are key devices for energy storage in modern day life. However, conventional LIBs suffer from several safety issues caused by the organic liquid electrolytes. Replacing the organic component with a piece of lithium-ion conductive ceramic, i.e., solid electrolyte, can in general solve the problem. Garnet-based oxide Li7La3Zr2O12(LLZO) is known to have good conductivity and stability when doped with proper dopants such as Ta, making it a promising solid electrolyte. However, due to the solid-solid contact problem with electrodes, the performance of solid-state batteries are not satisfactory.

We developed a modified plastic-crystal material based on succinonitrile that could be used as a deformable interlayer between electrodes and the solid electrolyte. The high lithium conductivity and the plasticity of the interlayer enables a good performance of the solid-state Li|LLZO|LiFePO4 battery even at room temperature. By adding a stabilizer to succinonitrile, we were able to use the interlayer at both LiFePO4|LLZO and Li|LLZO interface. The battery could be stably cycled at room temperature with a capacity of 140mAh/g.
Lattice Templating and Galvanic Coupling Effects on the Electrochemical Performance of Core/Shell Battery Materials
Authors: Moazzen Elahe , Timofeeva Elena V. , Segre Carlo U.
Published: February 2020

β-Ni(OH)2 is commonly used as the cathodic material in rechargeable aqueous battery systems due to its well-defined electrochemical redox activity, high electric potential, high theoretical specific capacity (289 mAh/g) and relatively low cost. However, β-Ni(OH)2/β-NiOOH cathodes are also known to have inherently low electrical conductivity, which often results in incomplete discharge, low Coulombic efficiency and slow rates of charge and especially discharge. In this study, Ni(OH)2 nanoparticles (100x20 nm platelets) were synthesized and coated with epitaxial Co(OH)2 shells and a series of Ni(OH)2/Co(OH)2 core/shell nanoplatelets with varying shell thickness (0.5 to 4.1 nm) were systematically investigated with a combination of scanning electron microscopy (SEM) with energy dispersive x-ray analysis (EDX), x-ray diffraction (XRD), in situ and ex situ x-ray absorption fine structure spectroscopy (XAFS), and electrochemical tests. Structure-property correlations revealed that electrochemical behavior and reversibility of Co(OH)2 redox conversion depends non-linearly on the shell thickness, with the best performance (99.6% of theoretical capacity of the composite material, 10% improvement over the performance of pristine Ni(OH)2 nanoparticles) achieved at shell thickness of 1.9±0.3 nm. We suggest that in addition to the improvement in electrical conductivity, such thickness dependent Co(OH)2 shell behavior and the superior performance are due to a lattice templating effect, and the galvanic coupling of core and shell materials. Homogeneous deposition of the shell is confirmed with XRD, SEM and EDX, while lattice templating effect was suggested from XAFS results showing that Co-M and Co-O distances are close to those of the Ni(OH)2 lattice in thin shells and shift gradually towards values of bulk Co(OH)2 as the shell thickness increases. From a combination of electrochemical and structural characterization of these composite nanomaterials, including in situ XAFS, galvanic coupling between the shell and core is proposed as a material activation mechanism, which explains the limited reversibility of the Co(II)/Co(III) oxidation in some cases. The prospect of applying this nanostructuring to other combinations of materials such as MnO2/Fe2O3 and Fe2O3/MnO2 will also be discussed.
Texture in Conversion Reaction and Electrochemical Properties of Nanoparticle Clusters
Authors: Tran Nam Xuan , Leban Levon A , Thomas Milana Cherie , Yang Yiqun , Meda Lamartine
Published: February 2020

Manganese oxide (MnO) nanoparticle clusters embedded in a carbon matrix were deposited using one-step chemical vapor synthesis method for application in lithium ion battery. High resolution transmission electron microscope (HRTEM) and x-ray diffraction show the nanoparticles are polycrystalline with particle size ranging from 5 to 20 nm. EDAX, HRTEM, and X-ray photoelectron spectroscopy (XPS) revealed the presence of carbon in the sample matrix. Galvanostatic discharge-charge (GDC) experiments were performed on the clusters between 3.0 and 0.05 V vs. Li/Li+ at C/2, C/3 and C/5 rates. During the first discharge at C/3 rate, a semi-plateau is observed at ~1.0 V which is corroborated by cyclic voltammetry (CV) and delivered ~100 mAh/g. Then a plateau at 0.5 V yields ~500 mAh/g. An additional 200 mAh/g is obtained from the slopping region from 0.5 to 0.1 V, which the due to the pseudo-capacitance. The initial reversible capacity is ~800 mAh/g at C/3. The first charge curve has two plateaus at ~1.3 V and ~1.5 V corresponds to the oxidation of Mn0 to Mn+2 and Mn+2 to Mn+3/+4, respectively. All subsequent curves show similar pattern. The capacity increases as the cycle number increases for both the discharge and charge. Ex-situ analyses of four identical samples cycled in the CV were carried in the at different cut-off voltages of 0.92 V and 0.28 V during reduction and 1.31 V and 2.13 V during oxidation. Interestingly, all four samples were still polycrystalline. XRD and HRTEM showed that the sample that was stopped 0.28 V (reduction) has the smallest particle size whereas the sample stopped at 2.13 V (oxidation) has the bigger grain size. The (111) reflection of the MnO nanoclusters was always present irrespective of the voltage cut-off. The (200) and (220) reflections of the (MnO) vanished during reduction and reemerged during oxidation and increased in intensity as the voltage increased. HRTEM revealed that carbon was present throughout the GDC and played a key role in the cyclibility of the MnO clusters by improving electronic conductivity.

Figure 1
(Invited) Advances in 2D Materials Production; From R&D to Commercialization
Authors: Wiper Paul , Gonçalves Gonçalo , Chen Bingan , Jouvray Alex , Teo Ken
Published: February 2020

Over the past decade there has been considerable research focus on 2D materials. In particular, graphene, hexagonal boron nitride (hBN) and the family of transition metal dichalcogenides (TMDs), to name a few, exhibit unique electronic, optical and physical properties which can be exploited within various technologies and new application areas.

Besides the extraordinary advances in 2D materials research, their commercialization still remains challenging, especially for applications like electronic/optoelectronics, advanced coatings and energy-storage systems, where high quality, large scales, high throughput and reproducibility are required. From the available growth techniques, which play an important role on the materials properties, chemical vapour deposition (CVD) has proved to meet the aforementioned requirements.

In this presentation an overview of our technology capabilities and CVD graphene systems are reported with an emphasis on which market these tools can penetrate. We introduce our roll-to-roll system which can produce continuous monolayer or multilayer graphene coatings onto a variety of substrates. Finally, we introduce our systems for 2D growth highlighting the benefits and versatility of the systems.
(Invited) Improving Conducting and Insulating Interfaces to 2D Materials
Authors: Franklin Aaron D
Published: February 2020

Silicon-based electronics remain the backbone of the ongoing digital revolution and continue to enhance the computational ability and accessibility of data. However, as the range of possible applications for electronics grows, so does the realization that there are distinct limits to what silicon can do. 2D layered materials, including graphene and transition metal dichalcogenides (TMDs), present nearly limitless possibilities for new electronic devices. While these materials are very encouraging based on their intrinsic properties, establishing conducting and insulating interfaces (needed to form useful 2D electronic devices) compromises the desirable intrinsic behavior. In this talk, recent advances in establishing scalable, high-performance conducting interfaces to semiconducting 2D materials will be presented. This includes the use of an in situ ion beam source to modify 2D materials during the deposition of contact metals in 2D field-effect transistors. The establishment of pure edge contacts using this approach is able to yield devices with ultimate scalability. In addition to the improvement of conducting interfaces, the ability to nucleate ultrathin insulating materials on the inert surface of various 2D materials will also be discussed. Using plasma-enhanced atomic layer deposition, sub-5 nm films can be realized without modification of the 2D crystal lattice or inclusion of a buffer layer. In some cases, the electronic properties of the 2D material are preserved and even enhanced at the device-level. Improvement of these critical conducting and insulating interfaces to 2D materials has wide-ranging value for their integration into new electronic and optoelectronic devices.
(Invited) Precision Synthesis of Subnanoparticles Using a Dendrimer Reactor
Authors: Yamamoto Kimihisa
Published: February 2020

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. Organic inorganic hybrid versions have also been produced, by trapping metal ions or metal clusters within the voids of the dendrimers. Their unusual, tree-like topology endows these nanometer-sized macromolecules with a gradient in branch density from the interior to the exterior, which can be exploited to direct the transfer of charge and energy from the dendrimer periphery to its core.

We show that tinchloride, SnCl2 and FeCl3 complexes to the imines groups of a spherical polyphenylazomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By attaching an electron-withdrawing group to the dendrimer core, we are able to change the complexation pattern, so that the core imines are complexed last. By further extending this strategy, it should be possible to control the number and location of metal ions incorporated into dendrimer structures, which might and uses as tailored catalysts, building blocks, or fine-controlled clusters for advanced materials.　The metal-assembly in a discrete molecule can be converted to a size-regulated metal particle with a size smaller than 1 nm as a molecular reactor. Due to the well-defined number of metal particles in the subnanometer size region, its property is much different from that of bulk or general metal nanoparticles.
Electrophoretic Co-Deposition of Graphene/Metal Oxide Platelets for Composite Electrode Fabrication
Authors: Rashti Ali , Oh Tae-Sik
Published: February 2020

Graphene-metal oxide composites have been recently introduced as promising materials for energy storage and heterogeneous catalysis. The synergy between graphene and metal oxide enhances the performance of these composite materials in comparison to their individual components.1 Improved electrochemical properties such as high capacity and cycling stability makes graphene-NiCo2O4 composite a promising supercapacitor electrode.2 In this work, we assemble the composite electrode by electrophoresis on graphite electrode. We firstly disperse graphene sheets in the electrolyte solution by electrochemical exfoliation3 of the graphite electrode. NiCo2O4 platelets, separately prepared from Ni and Co salts by chemical synthesis route4, were then added into the electrolyte solution to form graphene sheet-NiCo2O4 platelet mixture suspension. Finally, graphene sheets and NiCo2O4 platelets are assembled on the exfoliated surface of the original graphite electrode in one electrophoretic deposition step. Deposition parameter-composite microstructure relationship was studied in detail. Controlled parameters include nominal input mass ratio of the two components, magnitude of the electrical field, and electrolyte solution composition. The final composite electrode were characterized using cyclic voltammetry and electrochemical impedance spectroscopy to estimate its functionality for supercapacitor application.

Wu, Zhong-Shuai et al., Nano Energy
1, 107 (2012).

Wang, Huanlei et al., Nano Research
5, 605 (2012).

Parvez, Khaled et al., J. Am. Chem. Soc.
136, 6083 (2014).

Joshi, Nirav et al., RSC Advances
6, 92655 (2016).
Anticorrosive Coating Based on Glycerol and Polyurethane Organic-Inorganic Hybrids
Authors: Braz Álvaro Guimarães , Pulcinelli Sandra Helena , Santilli Celso Valentim
Published: February 2020

The corrosion of metallic materials is one of the most common natural problems encountered in the different fields of engineering. To delay the corrosion effects, some kinds of organic inorganic hybrid (OIH) coatings were tested as protective barrier. In this work we proposed the use of glycerol as a renewable source reagent for the development of a sol-gel green-coating based on polyurethane (PU) and siloxane (PU-Sil). The PU was synthesized from diisocyanate, MDI (4,4'-methylenebis (phenyl isocyanate)) and glycerol and the effect of the ratio of APTES ((3-aminopropyl) triethoxysilane) and MDI in the properties and structure of the PU-Sil material evaluated. The FTIR characterization showed that the OIH material has carbamate groups in the polymer chain that are related to PU formation and urea groups due to the formation of the link between free NCO groups and the siloxane. 13C and 29Si NMR/MAS spectra showed characteristic bands of the PU chain and siloxane polycondensation degree of about 80%, respectively. From the thermogravimetric analysis was possible to demonstrate the effect of APTES on the thermal stability of the material. The electrochemical impedance spectroscopy measurements performed on the PU-Sil coated carbon steel demonstrated the effect of the amount of siloxane in the corrosion protection performance in saline solution. Lifetimes longer than 125 days were verified from impedance over 106 Ohm.cm2 observed for PU-Sil coated carbon steel. The developed green sol-gel route allowed producing an OIH material of low cost, formed by cross-linked polymer chains with good performance for steel corrosion protection.

Keywords: green-coating, corrosion protection, polyurethane – siloxane.
The Effect of Nickel Alloy Chromium Content in Indirect-Fired CO2 Power Cycle Environments
Authors: Holcomb Gordon R. , Oleksak Richard P. , Carney Casey S. , Tylczak Joseph H. , Doğan Ömer N.
Published: February 2020

Power cycles in the fossil energy, nuclear, and concentrated solar industries, using pure supercritical CO2 (sCO2) as the working fluid, have been proposed that offer significantly improved conversion efficiency and lower levelized cost of electricity over current power systems. High creep strength nickel-base alloys are proposed for use at the higher temperature portions of the power cycles. In this study a series of Ni-xCr model alloys (where x = 5, 12, 14, 16, 18, 20, 22, 24) were exposed to both sCO2 at 700°C/200 bar for 1500 h and atmospheric pressure CO2 at 700°C for over 5000 h. In both tests, all Ni-Cr alloys, even the low-chrome Ni5Cr alloy, maintained low oxidation rates and chromia scales. For CO2+H2O+O2 mixtures at 750°C/1 bar, all alloys except Ni5Cr exhibited low oxidation rates and chromia scales. However, in other environments (air at 700°C/1 bar and steam at 700°C/200 bar) more Cr was needed to maintain low oxidation rates and chromia scales. This result shows that Ni-Cr alloys appear to be quite robust with respect to oxidation resistance in the pure and predominantly CO2 environments found in sCO2 power cycles.