bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Pyrochlore and Perovskite Electrodes Towards the Oxygen Evolution in Alkaline Media
Authors: Abreu Sepulveda Maria Angelica , Trinh Phong , Malkhandi Souradip , Quesnel David J , Narayanan S. R. , Manivannan A. 
Published: February 2020

The identification of economically feasible and high efficient materials towards the oxygen evolution (OER) and reduction (ORR) reactions in alkaline media will constitute a major advancement in a variety of technologies such as water splitting, elctrowinning, fuel cells and metal-air batteries. OER and ORR have proven to be catalytic dependent electrochemical processes, and thus, the catalytic material at the oxygen electrode plays an important role in the performance of such technologies. Numerous research studies have been carried out on the synthesis of new electrode materials in order to reduce the voltage loss associated with the oxygen reactions.
In the present work, a comparison of OER behavior of a group of pyrochlore materials (A2B2O7-δ), and non-noble transition metal perovskites (ABO3) will be presented. The pyrochlore and perovskite structures were synthesized by a facile two-step combustion method yielding high purity phases with crystallite size in the vicinity of 20nm. The synthesized compounds include La1-xCaxFeO3, Pb2Ru2O7, and their substitutions, compared to un-supported RuO2 prepared by thermal decomposition of RuCl3. The catalysts powders were dispersed on a Nafion containing solution to form a catalyst ink [1]. The samples were tested in alkaline media in a traditional three-electrode system under continuous N2purging. Among the characteristics that make pyrochlores attractive for oxygen electrodes, is the unusual framework containing high density of oxygen vacancies and their apparent ordering which is believed to aid in the oxygen anion mobility [2]. Perovskite materials are attractive due to the wide range of substituting elements that can be employed to tune their electrocatalytic properties.
All the samples were characterized by XRD for phase analysis, XPS for valency, SEM for surface morphology. The OER electrochemical performance has been investigated by means of steady state current measurements. XRD spectra of selected samples and the OER activity are presented in Figure 1a and 1b, respectively. The effect of dopant concentration on the oxygen evolution activity will be discussed.
Acknowledgements

This work is supported by the IGERT-NSF fellowship and partially funded by the US Department of Energy/NETL, Oak Ridge Institute for Science and Education (ORISE) fellowship.

References

[1] Malkhandi, S., Yang, B., Manohar, A.K., Manivannan, A., Surya Prakash, G.K., and Narayan, S.R., J. Phys. Chem. Lett. 2012, 3, 967-972.
[2] Hyoung Oh, S., Black, R., Pomerantseva, E., Lee, J-H., and F. Nazar, L. Nat. Chem. 2012, 4, 1004-1010.

Figure 1
New High Energy Capacity VB2/TiB2 Composite Transition Metal Boride Air Battery
Authors: Stuart Jessica , Lefler Matthew J. , Rhodes Chris , Licht Stuart 
Published: February 2020

Transition metal borides, such as vanadium diboride (VB2) and titanium diboride (TiB2), are studied as alkaline battery anode materials both individually and as a composite anode for an air cathode battery. Composite batteries containing various amounts of VB2 and TiB2 show evidence of a synergistic enhancement of the cells both in their discharge voltage and in their efficiency. In alkaline media, VB2 and TiB2 individually electrochemically oxidize to yield 11 and 6 electrons per molecule, respectively. These anodes deliver an intrinsic gravimetric charge capacity of 4,060 mAh/g for VB2 and 2,314 mAh/g for TiB2, which is 3 to 5 fold higher than a typical zinc anode. High energy densities are obtained by using a cathode active material, oxygen, located outside the battery itself. The discharge of nanoscopic-VB2 shows a single voltage plateau of ~1V as a result of the simultaneous oxidation of all 11 electrons, though the coulombic efficiency (the actual charge capacity vs. the theoretical charge capacity) is greatly dependent upon the capacity of the anode; on the other hand, two distinct plateaus are reported for the macroscopic-TiB2 discharge curve (the first at ~1V, the second at ~0.85V), indicating the possibility of a two-step anodic oxidation occurring, but the coulombic efficiency of these cells remains constant despite changes in anode capacity.
Three-Dimensional Si-Based Composite Nanorods Array Applied in Energy Storage System
Authors: Li Jing , Yue Chuang , Yu Yingjian , Sun Shibo , He Xu 
Published: February 2020

The rapid development of the integrated circuit (IC) and Micro/Nano-Electro Mechanical System (M/NEMS) technologies are promoting the continued emergence or commercialization of the miniaturized autonomous devices such as wireless sensor networks (WSN) in smart grid.[1-4] In order to operate independently, the micro/nano autonomous electronic devices must have on-board power supply. However, the battery miniaturization still can not keep pace with the size scaling-down of the CMOS electronic technologies, due to the poor electrochemical performance of the micro/nano batteries or the un-compatible battery fabrication process with the IC technologies. Currently, the transition from two dimensional (2D) to 3D rechargeable LIBs with better electrochemical properties in a small areal footprint was found to cope well with state-of-the-art semiconductor technologies conceptually providing new opportunities for micro/nano power systems in the future. [5-7]
In this work, the electrochemical performances of 3D hexagonal match-like Si/Ge nanorod (NR) arrays buffered by TiN/Ti interlayer, which were fabricated by a cost-effective, wafer scale and Si-compatible process, were demonstrated and systematically investigated as the anode in rechargeable batteries. The optimized Si/TiN/Ti/Ge composite NR array anode displays superior areal/specific capacities and cycling stability by reason of their favourable 3D nanostructures and the effective conductive layers of TiN/Ti thin films. Lithium/Sodium ion insertion behaviors were experimentally investigated in post-morphologies and elemental information of the cycled composite anode, and theoretically studied by the first principles calculation upon the adsorption and diffusion energies of sodium in Ge unit cell. The preferential diffusion of Lithium/sodium in Ge structure over in Si lattice was evidently proved.

References:

[1]. Scott E. Thompson and Srivatsan Parthasarathy, materialstoday, 2006, 9, 20-25.

[2]. Yunhao Liu, Yuan He, Mo Li, IEEE TRANSACTIONS ON PARALLEL AND DISTRIBUTED SYSTEMS, 24, OCTOBER 2013.
[3]. Jeffrey W. Long, Bruce Dunn, Debra R. Rolison, and Henry S. White, Chem. Rev., 2004, 104, 4463-4492
[4]. Timothy S. Arthur, Daniel J. Bates, Nicolas Cirigliano, Derek C. Johnson , Peter Malati, James M. Mosby, Emilie Perre, Matthew T. Rawls, Amy L. Prieto, and Bruce Dunn, MRS Bull., 2011, 36, 523-531.
[5]. Loïc Baggetto, Harm C. M. Knoops, Rogier A. H. Niessen, Wilhelmus M. M. Kessels, and Peter H. L. Notten, J. Mater. Chem.,2010, 20, 3703-3708.
[6]. Alireza Kohandehghan, Peter Kalisvaart, Kai Cui, Martin Kupsta, Elmira Memarzadeha, and David Mitlin, J. Mater. Chem. A, 2013, 1, 12850-12861.
[7]. Peter H.L. Notten, Fred Roozeboom, Rogier A.H. Niessen, and Loïc Baggetto, Adv. Mater., 2007, 19, 4564-4567.
The Role of Modified Graphene in Cathode Formulations for Lithium-Ion Batteries
Authors: Arbizzani Catia , Da Col Luca , De Giorgio Francesca , Mastragostino Marina , Soavi Francesca 
Published: February 2020

One of the main challenges in the development of lithium-ion batteries is to increase their specific energy by the use of high-voltage and high-capacity cathode materials. LiNi0.5Mn1.5O4 (LNMO) is one of the most promising materials with a theoretical specific capacity of 147 mAh/g and a Li+ deinsertion/insertion potential of 4.7-4.8 V vs Li+/Li. However, the use of LNMO raises the question of electrolyte decomposition at such a high potential with the consequent formation of a surface layer that affects the cathode and, hence, the cell performance. Interface stability issues are overcome by LiMxM1-xPO4 (LMP, with M=Fe, Mn) and Li3V2(PO4)3 (LVP) olivines, with Li+ deinsertion/insertion at potential ranging from 3.4 V to 4.5 V vs Li+/Li, that are widely investigated for their high specific capacity, near 170 mAh/g, and their intrinsic safety and environmental compatibility. However, the electronic and ionic conductivity of olivines need improvements.
We explored the effect of partially reduced graphene oxide on LNMO performance in conventional electrolyte [1] and here we investigate the role of modified graphene in LNMO- and LMP/LVP-composite materials. Morphological and structural characterization of the cathode materials and electrochemical tests of the corresponding electrodes will be reported and discussed.
[1] S. Monaco, F. De Giorgio, L. Da Col, M. Riché, C. Arbizzani, M. Mastragostino, J. Power Sources, submitted

Acknowledgments
The authors wish to thank ENEA and Italy’s Ministero dello Sviluppo Economico for financial support under the Program 2013 “Ricerca di sistema elettrico, Materiali catodici per batterie litio ione ad elevata energia”.
Constructing Anhydrous Hydrogen-Bonding Network in a Sulfonated Polymer Based Membrane for High Temperature Fuel Cell Applications
Authors: Li Yan , Wang Zhiyong , Hu Xiaohong , Chen George Zheng , Dai Sheng , Jin Xianbo 
Published: February 2020

Proton exchange membrane fuel cells (PEMFCs) are most promising clean powers for vehicles.1 Current PEMFCs relying on Nafion with water necessary for proton conduction can only work below 363 K owing to that Nafion loses its conductivity quickly in response to the inevitable evaporation of water at elevated temperatures. However, PEMFCs operating at temperatures higher than 423 K are highly desired to overcome many obstacles of present PEMFCs, such as slow reaction kinetics, CO poisoning of the electrode catalysts, and the complexity of water and heat managements.2-4 Great efforts have been paid to develop anhydrous PEMs for these high-temperature FCs, particularly, those based on inorganic acids possessing intrinsic high proton conductivities at above 423K have been extensively studied.3,4 Intermingling sulfonated polymers (SPs, such as Nafion) with non-volatile, thermally stable (up to 573 K) ionic liquids (ILs) for anhydrous PEMs has also attracted numerous attention, and ionic conductivities exceeding 10-2 S cm-1 have been reached. However, these PEMs often suffer from low proton transfer numbers (0.5~0.6), poor mechanical performanc, and the assembed H2-O2 FCs with these ILs based PEMs were often poor in performance at intermediate temperatures.5,6

Here we report an anhydrous hydrogen-bond fusing strategy for high-performance PEMs by introducing hydroxyl functionalized IL (IL-OH) into the SPs. The IL-OHs selected as both proton donators and acceptors, that are evidenced to be strongly hydrogen-bonded with both Nafion and some nano-inorganic matters. Consequently, an effective interconnected hydrogen-bond network forms in a HFIL/SP based hybrid membrane, endowing the PEM with robust mechanical and thermal stability. At temperatures >430K , the anhydrous ionic conductivity of this kind of PEM can reach higher than 50 mS cm-1 with a large proton transfer number close to 1. And the initial high performance of the assembled intermediate-temperature H2-O2 FCs showed promising applications of this new generation HFIL/SP PEMs.

References
[1] M. Z. Jacobson, W. G. Colella, D. M. Golden, Science 2005, 308, 1901.
[2] Q. F. Li, C. Pan, J. O. Jensen, P. Noyé, N. J. Bjerrum, Chem Mater, 2007, 19, 350.
[3] J. A. Asensio, E. M. Sanchez, P. Gomez-Romero, Chem. Soc. Rev. 2010, 39, 3210.
[4] D. A. Boysen, T. Uda, C. R. I. Chisholm, S. M. Haile, Science 2003, 303, 68.
[5] M. Martinez, Y. Molmeret, L. Cointeaux, C. Iojoiu, J.-C. Leprêtre, N. El Kissi, P. Judeinstein, J.-Y. Sanchez, J. Power Sources
2010,195, 5829-5839;
[6] S. Y. Lee, A. Ogawa, M. Kanno, H. Nakamoto, T. Yasuda, M. Watanabe, J. Am. Chem. Soc. 2010, 132, 9764-9773
Corrosion Behavior of Stainless Steel Coated Graphene Layers for Polymer Electrolyte Membrane Fuel Cell Bipolar Plates
Authors: Lee Seokhee , Park Hyejin , Chung Yoonsung , Lee Eunji , Ahn Soohyun , Kim Dong-Joo 
Published: February 2020

Metallic materials such as stainless steel are considering as a bipolar plate for polymer electrolyte membrane fuel cells (PEMFCs) due to their low bulk electrical resistivity, high heat conductivity, high mechanical strength, gas impermeability, low cost, and ability to produce thin sheets or foil (0.1 - 1 mm thick) form to achieve high power densities [1]. However, its corrosion resistance in working conditions of PEMFCs is still far from satisfaction. In addition, metal ions produced during the corrosion process decrease the ionic conductivity of Nafion®membrane and reduce the overall efficiency of a cell due to contamination of the catalysts [2]. Various coating materials such as ceramic-like nitride, carbides, conducting polymers, and surface modification of a substrate using thermal nitridation have been investigated to satisfy the requirements for bipolar plates [3]. Especially, carbon coating materials have received significant attention, because such materials supply excellent corrosion resistance, electrical conductivity and chemical stability in working conditions of PEMFCs [4]. In this study, carbon layers were coated on the surface of stainless steel plates to be used as bipolar plates in PEMFCs by spin coating system. Graphene oxide composite suspensions were used as coating materials. The graphene oxide layers were thermally reduced to increase the electrical conductivity. Microstructural analysis of the reduced graphene oxide layers were investigated by means of Raman spectroscopy, field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). For in-depth analysis of the corrosion properties, the electrochemical performance of the graphene coating layers was evaluated by the poteniodynamic method under simulated working conditions of PEMFCs, and the mechanism on corrosion resistance is discussed in detail.
References
[1] S.H. Lee, T.H. Tang, S.H. Hyun, Y.S. Yoon, Corros. Sci., 58 (2012) 79-85.
[2] S.H. Lee, V.E. Pukhac, V.E. Vinogradovc, N. Kakatia, S.H. Jee, S.B. Cho, Y.S. Yoon, Int. J. Hydrogen Energy, 38 (2013) 14284-14294.
[3] R. Taherian, J. Power Sources 265 (2014) 370-390.
[4] K. Feng, Z. Li, F. Lu, J. Huang, X. Cai, Y, Wu, J. Power Sources 249 (2014) 299-305.
Thin Film Electrodes and Electrochemical Reactions at Three-Phase Boundary in Alkaline Media: A DFT Approach
Authors: Kubal Joseph , Zeng Zhenhua , Greeley Jeff 
Published: February 2020

With increased energy demands, fuel cells offer a viable solution due to their efficient conversion of energy from various fuels. Switching to a basic electrolyte, many metals that would be susceptible to corrosion in an acidic environment become stable in an alkaline one. This allows for the inclusion of non-precious metals in the electrodes. However, the kinetics in an alkaline environment tend to be sluggish; this must be overcome for alkaline fuel cells to become commercially realizable. While many model electrodes have been investigated for possibility to improve the kinetics in alkaline fuel cells, this work focuses on thin film electrodes and reactions happening at the interphase between the substrate and the film. The introduction of three-phase boundaries can allow the various reaction intermediates to preferentially bind to different locations, thus possibly allowing one to break away from scaling relationships. This could ideally enable the catalyst to reach higher catalytic activity [1].
To determine the effectiveness of these electrodes, density functional theory (DFT) is employed. Before work was done to model the interphases, extensive work was done examining various moiré patterns for various oxidation states of transition metal films, with a focus on FeOxHy films. In this work, the stability of a variety of transition metal (hydr)oxide thin films on Pt and Au are first examined for stability for their future prospects of viable catalysts for fuel cell applications. In addition, phase diagrams are constructed to determine the state of the film at a given voltage, something crucial for designing optimal catalysts. A DFT + U scheme is employed to model the thin films, where U values are fitted by correcting the formation energies.
While the oxidation state and strain of the film are predicted from the full film phase diagrams, the nature of the interphase needed to be determined. The focus , hydrogen evolution and CO oxidation at these interphases with each reaction occurring at a different equilibrium potentials. This knowledge necessitated the creation of phase diagrams for the interfaces, to identify the most stable oxidation state the edge may take. With these phase diagrams, the thermodynamics and kinetics for the two reactions could be calculated with DFT along with nudged elastic band (NEB) calculations to calculate the activation barriers. These results are then compared with those on a clean Pt surface.
[1] R. Subbaraman, D. Tripkovic, K. Chang, D. Strmcnik, A. P. Paulikas, P. Hirunsit, M. Chan, J. Greeley, V. Stamenkovic, N. M. Markovic. Nature Materials. 11, 550 (2012)
Synthesis, Pore and PTFE Distribution Studies of Monolithic Gas Diffusion Media for PEMFC By Varying Solvent
Authors: Kattamanchi Sruthi , Prathap Haridoss 
Published: February 2020

Proton Exchange Membrane Fuel cells (PEMFC) are the focus of research internationally, due to their potential in solving energy problems by enabling energy conversion in a clean manner. Gas Diffusion Medium (GDM) is a vital component of a PEMFC which controls the transport of gas and water molecules. The performance of a fuel cell is impacted by mass transport losses. Existing GDMs are based on carbon paper and carbon cloth structures that are commercially available and have specific structures. These commercially available starting materials therefore restrict the overall design of the GDM to work within the constraints of their structure.
In the present work the focus is to make a combined porous self standing GDM constituting meso and macro pores using Carbon black (CB) and PTFE. PTFE content as well as its distribution play a prominent role in wicking out water from the reaction site. Method for preparation of the self standing GDM is tailored with starting materials such as CB, Graphite, and Teflon. Factors affecting the uniform distribution of PTFE are identified. Pore size, uniformity and pore distribution obtained through the use of four different solvents – IsoPropylAlcohol (IPA), Glycerol, Ethanol, and Water, are studied. The GDMs prepared are characterized using SEM and Mercury Intrusion Porosimetry. Pore distribution, sizes and composition are examined using SEM images and composition maps on a comparative basis. Optimization of conductivity, hydrophobicity and water transport is carried out. The results obtained are presented and discussed and compared. The advantages a particular solvent and factor contributing an uniform PTFE distribution is recognized as a part of this approach.
Controlling Polysulfide Shuttling in Lithium-Sulfur Batteries
Authors: Pathak Manan , Suthar Bharatkumar , Subramanian Venkat 
Published: February 2020

Most electric cars run on rechargeable lithium-ion batteries, a pricey technology that accounts for more than half of the vehicle's total cost [1]. The development of renewable, low cost, high performance energy technologies is a key scientific challenge. Active research is being pursued to develop a new technology that can replace Li-ion batteries. One promising alternative is the lithium-sulfur battery, which can theoretically store five times more energy at a much lower cost [2].
The major drawback of a lithium-sulfur battery is the polysulfide shuttling [3, 4] between anode and cathode, which induces low Coulombic efficiency, low utilization of the sulfur cathode, and severe degradation of cycle life. In this work, an electrochemical engineering model [2, 5, 8, 9] is used to understand the shuttling mechanism. In particular, the electrochemical engineering model will be reformulated for improved computational efficiency to enable real-time simulation and model based control [6, 7]. The control of polysulfide shuttle across the electrodes will be explored by obtaining optimal charging profiles. Controlling the polysulfide shuttling would ensure a longer battery life for the lithium-sulfur battery [10].

Acknowledgements

The work presented herein was funded in part by the Clean Energy Institute at the University of Washington, Seattle.

References

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M. R. Busche, P. Adelhelm, H. Sommer, H. Schneider, K. Leitner and J. Janek, Journal of Power Sources, 259, 289-299, 2014.

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Increased Conductivity of Li2xMg1-Xo/Nanostructured Carbon Composites
Authors: Chayed Nor Fadilah , Kamarulzaman Norlida , Rusdi Roshidah , Abdul Aziz Nor Diyana 
Published: February 2020

Lithium conducting ceramics are important for applications in thin film batteries. In this work, novel Li2xMg1-xO materials were synthesized by the sol-gel method. Optimization of the synthesis method showed that annealing at 950 oC gave pure, single phase materials of cubic crystal structure. Conductivity studies, using a.c. impedance showed that incorporating nanostructured carbon enhances the conductivities of the composite materials. The nanostructured carbon acted like a bridge connecting the voids between the crystals and improved the electronic and Li+ ionic diffusion through the materials.