bluuebunny/crossref_metadata_2025_split huggingface dataset:
Elucidating Electrodeposition Mechanisms in Li-Ion Battery Anodes
Authors: Hao Feng , Mukherjee Partha P. 
Published: February 2020

Metal plating and dendrite are widely observed in the electrochemical processes, such as electrodeposition and Li-ion battery charging cycles. In this work, a mesoscale modeling approach is developed for investigating the mechanisms of Li plating and dendrite on Li-ion battery anode surface. We explore the possible origins and the kinetics of these phenomena. Specifically, we investigate the effects of the anode surface wetting, Li surface self-diffusion, local overpotential, surface geometry, and temperature on the formation mechanisms of Li plating and dendrite. More importantly, we explicitly clarify the competition between these factors and quantify their contributions to the final Li morphology. From this study, we aim to shed light on the Li deposition behaviors on the anode surface and provide guidance for facilitating Li plating and avoiding Li dendrite.
Figure. Li deposition morphologies: (a) dendrite and (b) layered by layered film.

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Effect of Halide Doping on the Structure and Properties of Na3SbS4 Solid Electrolyte
Authors: Wang Hui , Schultze Trevor M , Kang Luhao , Dewees Rachel , Hood Zachary D. 
Published: February 2020

Compared to Li-ion batteries, rechargeable sodium (Na) batteries hold much promise for medium and large-scale energy storage systems due to the decreased price, natural abundance and suitable electrochemical window of Na metal. In addition to Na-S and ZEBRA batteries, solid-state Na batteries that operate at room temperature are highly desirable. To realize this target, solid electrolytes with highly ionic conductivities are necessitated. Na3SbS4 is a newly discovered Na-ion conductor [1] and exhibits an excellent ionic conductivity of 1 mS cm-1. To further improve its performance in solid-state Na batteries, faster Na-ion transportation through Na3SbS4 is expected. In this report, we introduced halide ions into Na3SbS4 solid electrolyte and studied doping effect on the crystal structure and conductive properties of Na3SbS4. It was found that the iodide (I-) doping expanded the lattice structure of Na3SbS4 without generating a new phase. Tuning the dopant concentration led to an overall higher ionic conductivity in doped Na3SbS4. The enhancement of ionic conductivity is explained by the creation of vacancies due to alivolent anion substitution.
Reference
[1] Wang, H., Chen, Y., Hood, Z.D., Sahu, G., Pandian, A.S., Keum, J.K., An, K. and Liang, C., An Air‐Stable Na3SbS4 Superionic Conductor Prepared by a Rapid and Economic Synthetic Procedure. Angewandte Chemie International Edition, 2016, 55(30), pp.8551-8555.
Imaging of Representative Volumes in Battery Electrodes and Direct Visualization of Lithium Atoms: Recent Advances in Electron Microscopy
Authors: Lemmens Herman 
Published: February 2020

There are different ways to create a 3D image of the battery electrodes.
MicroCT uses the absorption of X-rays to create a 3D reconstruction. The Field of View is large enough to be representative with regard to the grain sizes (1). However, the submicron porosity in the electrodes is typically not well captured by microCT because of its limited resolution.
The FIBSEM technique which uses a Galium ion beam for sectioning and an electron beam for imaging has high enough resolution to resolve all porosity. However, the Field of View is typically of the order of 10 micrometer; which is not big enough to create a representative model of the pore space.
In this study we have used a plasmabeam for sectioning and an electron beam for imaging. The plasmabeam typically removes a layer of 100 nm followed by imaging by the electron beam. The material removal rate with the plasmabeam is magnitudes higher than with the Ga focused ion beam, allowing to expand the field of view to hundreds of micrometers.
A 3D reconstruction of the anode (Field of View 200micrometer) and the cathode (Field of View 100 micrometer) make it possible to calculate parameters such as the tortuosity on a representative volume.
Segmentation of the pore space is not straightforward due to minimal grey level differences between the different phases. Also, it is not uncommon to see details from layer N+1 through the pores in layer N. This so-called pore-back effect must be taken into account otherwise the permeability will be greatly underestimated.
Direct imaging of light elements such as lithium in the crystal structure of a compound by Transmission Electron Microscopy is typically a difficult task. In most cases the position of the light elements is deduced from image simulations using different defocus and thickness values.
Starting from the theory of scanning transmission electron microscopy imaging we have proven that it is possible to image the phase of a thin sample directly and linearly when use is made of the center of mass (COM) movement of the convergent beam electron diffraction pattern. Integrating the two components of the COM image gives an image which is directly proportional to the phase shift caused by the sample.
Experiments show that both light and heavy elements are visible and that low frequency information is fully transferred. Examples are shown where lithium is directly visualized in the structure of a typical cathode active material.

Cai et al, Electrochimica Acta 56 (2011) 5804–5814
Surface Functionalization of Silicon Nanoparticles with Citric Acid for Enhanced Performance As Lithium Ion Battery Anodes
Authors: Lucht Brett L , Chandrasiri Dilni Kaveendi , Jurng Sunhyung , Subramanian Parimalam Bharathy , Nguyen Cao Cuong , Young Benjamin , Heskett David 
Published: February 2020

Among advanced materials studied to enhance the performance and energy storage of Li ion batteries, silicon nanoparticles have shown great potential as an anode material with its high theoretical gravimetric capacity of approximately 4200 mAh/g which is ~10 times higher than that of the commercially used anode material graphite. Nevertheless, the volume expansion of ~400% during the lithiation causes the electrode to suffer from rapid degradation, thus leading to poor cycle life. In this study we discuss the surface modification of silicon nanoparticles with citric acid for better cycling performance and capacity retention of silicon based electrodes. The objective of the study is to form a protective layer on silicon nanoparticles that will reduce the strain caused by volume variation due to lithiation and delithiation in the cycling process.
Cycling performance studies have been conducted on 50% silicon containing electrodes as well as graphite silicon composite electrode (70:15 weight % respectively). Both types of electrodes have shown promising cycling performance data when the surface of was functionalized with citric acid. The results indicate good capacity retention of ~60% after 50 cycles from surface modified silicon electrodes as opposed to 45% with the surface unmodified electrode. Chemical and surface analytical techniques such as Fourier transformation infrared spectroscopy(FTIR), Xray photoelectron spectroscopy (XPS), hard x-ray photoelectron spectroscopy (HAXPES), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), electrochemical impedance spectroscopy was used to analyze the nanoparticle surface as well as the solid electrolyte interphase formed on the electrodes to further understand how this protective layer improve the performance and the results of this study will be discussed.

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Engineering Novel Fiber Structures As Wearable Supercapacitors
Authors: Gao Wei 
Published: February 2020

Recently, fiber/yarn-based energy-storage systems have attracted enormous attention due to their remarkable promises in smart textiles and high-tech sportswear etc., mainly as more pliable energy-storage units being truly “wearable”. Scalable, inexpensive manufacturing processes that produce yarns capable of storing energy are required for new breakthroughs within the wearable electronics sector. For example, US Army is looking for the manufacturing processes capable of producing kilometers of energy-storage yarns that retain desirable mechanical attributes and can be knitted or woven into wearable fabrics. However, so far such processes are still missing. Current technologies include modified textile yarns, composite yarns containing metal wires, polymers, carbon nanotubes (CNTs), metal oxides, and conductive carbon yarns etc. However, several issues exist in current systems, including the biosafety of CNTs, the weight and corrosion of metal wires, and long-term stability of conductive polymers. These issues need to be addressed before they can be employed for practical use.
Here we introduce a unique process of making graphitic yarns (yarns made of graphitic carbon flakes) that has attracted enormous attention internationally. Yarns made of graphite flakes are lighter and more corrosion-resistive than metal wires, and more stable in electrical conductivity than polymers. More importantly, graphite flakes are generally considered to be biofriendly, since they have been used as the major component in pencils for decades. Furthermore, the process of making graphite fibers has several advantages: 1) large-scale availability of the wet-spinning dope, which is graphite oxide dispersions in water; 2) fiber/yarn precursors labile for various chemical/physical modifications; 3) graphite used as the major precursor, which is low cost and abundant in nature; 4) several prototypes have been demonstrated. This talk will introduce our recent research on process engineering and chemical modification of the detailed yarn structures for high energy density and mechanical flexibility.
Determining Electro-Osmotic Drag of Water in Anion Exchange Membrane Fuel Cells
Authors: Roy Asa Logan , Peng Jing , Zawodzinski Thomas A. 
Published: February 2020

In an effort to reduce the cost of proton exchange membrane fuel cells (PEMFCs), a significant amount of research into non-precious metal (NPM) oxygen reduction catalysts has been conducted in recent decades. Despite this effort, platinum remains the only material with suitable stability and activity for use in the harsh environment of PEMFCs. Anion exchange membrane fuel cells (AEMFCs) have been gaining increased attention in recent years, providing advantages of higher stability and activity of NPM catalysts in alkaline environments.
Unfortunately, the relevant properties, e.g. conductivity and mechanical & chemical stability, of anion exchange membranes (AEMs) are inferior to their proton conducting counterparts. Many studies have been conducted which focus on improving membrane properties such as swelling ratio, conductivity, and stability. In comparison, relatively little attention has been paid to studying ion and water transport in anion exchange membranes.
Previous work conducted in our group has indicated that the majority of AEMFC polarization arises from the anode. The performance is relatively insensitive to catalyst loading and initial results indicate that electrode flooding is the primary cause of poor performance. To improve the performance of AEMFCs and better design AEMs, it is therefore important to study the transport of water and ions within AEMs. One key parameter which has received very little attention in the literature is the electro-osmotic transport of water due to the conduction of anions from the cathode to the anode.
In this work, we study the electro-osmotic drag (EOD) in anion exchange membranes. The cell design and concept for electro-osmotic drag coefficient (ε) measurements in this work follow from the work of Fuller and Newman as adapted by others1–3. Analysis is conducted on the membranes in pure hydroxide form and carbonate form. The conductivity, water uptake and water mobility of the membranes is also studied over a wide range of relative humidities and temperatures.
Better understanding of the transport of water and ions within anion exchange membranes will facilitate the development of models for AEMFC behavior and offer insight for future AEM production.
Figure 1: Effect of water activity on the EOD coefficient (ε) and water content (λ) in Tokuyama A201.

T. F. Fuller and J. Newman, J. Electrochem. Soc., 139, 1332–1337 (1992).

T. A. Zawodzinski, J. Davey, J. A. Valerio, and S. Gottesfeld, Electrochim. Acta, 40, 297–302 (1995).

X. Wang, J. P. Mcclure, and P. S. Fedkiw, Electrochim. Acta, 79, 126–132 (2012) http://dx.doi.org/10.1016/j.electacta.2012.06.098.

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Miniature Fuel Cell with Monolithically Fabricated Si Electrodes - Application of a Polymer Electrolyte Membrane with Adapted Shape
Authors: Kushida Yuta , Sawada Asuka , Kono Koichi , Oshiba Yuhei , Yamaguchi Takeo , Hayase Masanori 
Published: February 2020

Miniature fuel cells have attracted attention as an ultimate portable power source, and we have developed monolithically fabricated Si electrodes for the miniature fuel cells [1]. In the fuel cells, two Si electrodes with porous Pt catalyst layer are pressed onto either side of a PEM (polymer electrolyte membrane) , and the prototype fuel cells showed promising performances of over 500mW/cm2 output at 313K with H2-O2. However, the high output was obtained with only 1 mm2 reaction area. Along with enhancement of the reaction area, the performance dropped. We assumed that the performance drop is caused by poor adhesion between Si electrodes, because the porous Pt layer becomes depressed several micrometers from the substrate surface during the formation process using anodized porous Si and voids appears at interface between electrodes and PEMs as shown in figure 1(a).
In this study, we attempted to adapt PEM shape to the depression of the porous Pt catalyst layer as shown in figure 1(b). Generally, swelling of PEM caused serious damages to miniature fuel cells because of their fragile nature of porous-Pt and we have employed pore-filling membranes to avoid the swelling in our fuel cells. The pore-filling membrane has two components: a porous polymer substrate to provide mechanical strength and an electrolyte polymer in the pores for proton conductivity. In order to machine the PEM to fit the depression, we decided to apply O2 plasma etching to the porous polymer substrate and fill electrolyte polymer into the substrate after the shaping, because damage to electrolyte with long O2 plasma irradiation was a concern. To protect the central area of the porous polymer substrate from the plasma, circular copper plate was used as a mask and was put on the substrate in the process chamber. Plasma etching was applied on both side of the substrate. Figure 2 shows the porous polymer membrane after the plasma etching. As we expected, the substrate has circular thick area. Gas permeability of the porous polymer substrate did not change even after the several micrometers etching, and it was assumed that porous structure was maintained at plasma irradiated area. After the shaping, 2-acrylamido-2-methylpropan sulfonic acid (AMPS) was filled in to the substrate and the monomer was polymerized by heating [2]. Prototype cells with 4mm2 reaction area with the proposed adapted shape PEM and conventional flat PEM were made and power generation tests were performed. With the adapted shape PEM prototypes, 780 mW/cm2 at average and max. of 1050 mW/cm2 outputs were obtained, which is the best among our results. While with conventional PEMs, average output was 320 mW/cm2 and even maximum was 420 mW/cm2.

References

[1] M. Kobayashi, T. Suzuki, M. Hayase, Journal of Power Sources, 267, 622-628 (2014).
[2] T. Yamaguchi et al., Journal of Membrane Science, 214, 283-292(2013).

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Rational Design of Ir-M Nanoalloy for PEMFC Cathode Application: Combined Computational and Experimental Study
Authors: Cho Jinwon , Jang Injoon , Park Hyun-Seo , Choi Sun Hee , Jang Jong Hyun , Kim Hyoung-Juhn , Yoon Sung Pil , Yoo Sung Jong , Ham Hyung Chul 
Published: February 2020

Despite recent efforts on replacing a noble Pt to less expensive catalysts for improving oxygen reduction reaction (ORR) for PEMFC (polymer electrolyte membrane fuel cell) application, the performance and stability of a noble Pt catalyst remains superior. In this presentation, we have systematically designed the novel Ir-based ORR catalyst for the PEMFC application via the combined density functional theory (DFT) and experimental approach.
First, we computationally screened the potential M element and near-surface composition in Ir3M nanoalloy (M = 3d, 4d, 5d metals) for the purpose of enhancing the activity and durability of catalyst in ORR by considering Gibbs free energy change for alloy formation process, oxygen binding energy and segregation energy of inside M element toward surface layer under vacuum and oxygen environment. Our DFT-based screening identified the pure Ir monolayer on the top of Ir3­Cr, Ir3­V, Ir3­Re, and Ir3­Tc alloy cores as the promising candidates for improving ORR activity and durability.
Next, a pure Ir monolayer on the top of Ir3­Cr core (which was expected to show the most enhanced ORR activity among the computationally-screened candidates) was experimentally prepared via physical vapor deposition method (PVD) and electrochemically evaluated for confirming our DFT prediction. We successfully synthesized a 3nm Ir-covered (Ir skinlayer) Ir3­Cr nanoparticle whose surface lattice distance was contracted by 1.03% compared to the pure Ir case. The specific activity (at 0.7 V vs RHE) of a Ir skinlayer/Ir3Cr catalyst with the very high durability (showing only 0.05 % decrease from the initial activity after 3000 potential cycles) was 12.3 times higher than a Ir catalyst. The detail mechanism on the enhanced activity in Ir-M alloy was also examined.
Our theoretical and experimental study highlight the general methodology for designing metal-based alloy catalysts for the application to ORR in PEMFC and such method can be further extended to the development of the next-level electrocatalyst for energy conversion.
Current and Temperature Distribution Measurement in a Polymer Electrolyte Membrane Water Electrolyzer Cell
Authors: Zhou Fan , Al Shakhshir Saher , Kær Søren Knudsen 
Published: February 2020

The uniform distribution of the current and temperature under the normal operating conditions of the polymer electrolyte membrane water electrolyzer (PEMWE) cell is important to ensure its high efficiency and durability. In this work, a segmented sensor plate S++ is inserted between the flow field plate and current distributor plate at the cathode side of a single PEMWE cell to measure the local current and temperature distribution under different water flow configurations of the anode and cathode side and various current loads of PEMWE. The active area of the single PEMWE cell is 50 cm2. One hundred segments in the segmented sensor plate provide high resolution in the current and temperature distribution measurement. The current and temperature distribution are measured under co-flow and counter-flow of water recirculation between anode and cathode and under different current loads from 10A to 70A. Besides, the polarization curve and electrometrical impedance spectrum are measured under different water flow configurations.
Initial results reveal that when operated with co-flow of water re-circulation in anode and cathode, the cell shows better performance. With co-flow configuration, the charge transfer for hydrogen evolution and oxygen evolution reaction is larger compared with counter-flow configuration. The current shows similar distribution pattern under different water flow configuration and different current loads. However, uniformity in current distribution becomes better with lower current. The temperature distribution is not significantly influenced by the current load, while the counter-flow of water re-circulation results in more uniform temperature distribution.

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Neutron Radiographic Investigations on the Effect of Hydrophobicity Gradients within MPL and MEA on Liquid Water Distribution and Transport in PEMFCs
Authors: Mohseninia Arezou , Kartouzian Dena , Markötter Henning , Ince Utku U. , Scholta Joachim , Manke Ingo 
Published: February 2020

Neutron radiography imaging is employed to investigate the effect of hydrophobicity gradients between the membrane electrode assembly (MEA) and microporous layer (MPL) of a low-temperature polymer electrolyte membrane fuel cell (PEMFC) on the water distribution and transport in operating cells. Single cells specially developed for neutron imaging experiments with an active area of 8 cm² are equipped with in-house made MEAs and MPLs featuring different degrees of wettability. Imaging is performed with a pixel size of 13 µm and the cells are operated at two different current densities of 1 and 0.75 A cm-2 and a relative humidity of RH=70% and RH=120% at a temperature of 55°C. A first quantitative analysis of the water thickness in electrodes and gas diffusion layers (GDLs) of 3 cells at RH=120% and i=1 A cm-2 as well as an exemplary radiogram for the water distribution inside one of the cells is shown in figure 1.
It is observed that the implementation of both a more hydrophobic MEA and MPL results in an increase of overall water content inside the cell. Nevertheless, the effect of a more hydrophobic MPL on the increase of the water content of the cell, under the operating conditions investigated here, is apparently more significant compared to the effect of a more hydrophobic MEA. As expected, the amount of water found on the cathode side is higher than on the anode side for all components of the cell. The sudden accumulation of water on anode side which is appearing in periodic peaks with equal time intervals is associated to an increased rate of back diffusion mechanisms. The cell with a more hydrophobic MEA has decreased the magnitude of these fluctuation peaks by 30%, whereas this reduction ratio is 60% for the cell with more hydrophobic MPL, resulting to a more balanced water profile across the membrane. In this presentation, we will show further morphological and wetting property characterization results of various MEAs and MPLs and analyze the effect of hydrophobicity on the dynamical changes of water distribution and transport at different operating conditions.

Figure 1