bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards a Better Understanding of Aprotic Alkali-Oxygen Batteries
Authors: Nazar Linda F , Kundu Dipan , Xia Chun , Black Robert , Adams Brian , Fernandes Russel 
Published: February 2020

In the search for high density electrochemical energy storage, non-aqueous rechargeable metal-O2 batteries are very attractive owing to their reliance on molecular oxygen, which forms oxides on discharge that release oxygen reversibly on charge. Much work has focused on aprotic Li–O2 cells, but the aprotic Na-O2 system is of equal interest owing to its more reversible chemistry. In both cells, a chemically stable and conductive cathode interface is prerequisite for sustainable cell operation, along with a non-aqueous electrolyte that minimizes parasitic reactions at the electrode/electrolyte interface. Li-O2 cells (unlike their sodium counterparts), are also characterized by a high charge overpotential that must be overcome in order to increase round-trip efficiency. In the last year, much progress has been made towards achieving these goals owing to a better understanding of the cell chemistries. This presentation will focus on those topics, covering developments from our lab that include non-carbonaceous cathode hosts that possess stable conductive interfaces for reduced polarization on O2 evolution, and novel soluble oxidation catalysts capable of Li2O2 oxidation without direct electrical contact with the cathode. Characterization techniques ranging from electron microscopy, surface spectroscopy and operando electrochemical mass spectrometry have been applied to investigate the viability of various proposed systems. This has resulted a deeper understanding of the critical parameters for positive electrodes in aprotic A-O2 batteries, which will be presented in this talk.
Investigation of the Graphene Supported Platinum-Tungsten Catalysts Prepared By Microwave Synthesis As Electrocatalysts for Borohydride Oxidation
Authors: Kilmonis Teofilius , Tamasauskaite-Tamasiunaite Loreta , Balciunaite Aldona , Vaiciuniene Jurate , Norkus Eugenijus 
Published: February 2020

In the study presented herein a rapid microwave heating method was used to prepare the graphene supported platinum-tungsten catalysts (denoted as Pt-W/GR) with the different Pt:W molar ratios. The prepared catalysts were characterized by means of Transmission Electron Microscopy, X-ray diffraction and Inductively Coupled Plasma Optical Emission Spectroscopy. The electrocatalytic properties of the Pt-W/GR catalysts towards the oxidation of borohydride in an alkaline medium were investigated by means of cyclic voltammetry and chrono-techniques.
It was found that the graphene supported platinum-tungsten catalysts with the Pt:W molar ratios equal to 1.6:1, 2.4:7 and 7.1:1 were prepared by microwave-assisted heating of Pt(IV) and W(VI) salts in ethylene glycol solutions.
It has been determined that the synthesized Pt-W/GR catalysts with the different Pt:W molar ratios show an enhanced electrocatalytic activity towards the oxidation of H2 generated by catalytic hydrolysis of BH4
– and direct oxidation of BH4
– comparing with the graphene supported bare W catalyst. The Pt-W/GR catalyst having the Pt:W molar ratio equal to 7.1:1 exhibits the highest electrocatalytic activity for the both oxidation reactions of H2 and BH4
– ions as compared with that at the Pt-W/GR catalysts with the Pt:W molar ratios equal to 1.6:1 and 2.4:1.
Investigations on Oxygen Evolution Catalysts for PEM Electrolysis Cells
Authors: Waltar Kay Erik , Fabbri Emiliana , Schmidt Thomas J. 
Published: February 2020

In recent years, electricity-driven hydrogen production by electrochemical splitting of water (water electrolysis) has received particular attention because of its potential applicability in decentralized energy storage concepts. The electrolysis of water is nowadays mainly performed in alkaline or acidic electrolytes. The acidic polymer electrolyte electrolysis cell (PEEC) has distinct advantages over the alkaline liquid electrolyte devices. PEECs can rapidly respond to changes in the power input and operate at a larger partial load range. Furthermore, high voltage efficiencies and the possibility to be operated at high pressures > 100 bar favor its use. Nevertheless, the anodic oxygen evolution reaction (OER) is catalytically demanding, showing high overpotentials. Additionally, the strongly oxidizing environment reduces the set of applicable materials to a few noble transition metal (mixed-) oxides. Transition metal oxides based on ruthenium and iridium constitute the state of the art catalysts for the OER performing with high catalytic activity and sufficient stability1. The low availability of iridium raises its costs and new catalyst materials and/or surface morphologies have to be investigated to either replace or reduce the iridium content. For this purpose, a promising strategy is to develop catalyst materials as mixed oxides with non-noble substitutes and a high surface area. These new materials need to be characterized with respect to their performance and stability. Especially, at the high potentials which are needed to drive the oxygen evolution reaction, a thermodynamic instability of the catalysts lattice oxide anions may lead to an oxygen evolution from the lattice and concomitantly to an electrochemical corrosion of the material. Rotating ring-disc electrodes (RRDEs) enable the estimation of generated oxygen and thereby the determination of the catalysts current efficiency. Within this study the RRDE method will be applied to several promising OER catalysts to determine their current efficiencies. In addition, the materials stability with respect to its application in electrolysis cells facing intermittent power input will be investigated.
Financial support of this project by CCEM (RENERG2), the Commission for Technology and Innovation (CTI) and the Swiss Competence Center for Energy Research (SCCER) Heat & Electricity Storage is gratefully acknowledged.
1. Fabbri, E.; Habereder, A.; Waltar, K.; Kötz, R.; Schmidt, T. J., Developments and perspectives of oxide-based catalysts for the oxygen evolution reaction. Catalysis Science & Technology
2014, 4 (11), 3800-3821.
2. Kötz, R.; Stucki, S., Stabilization of RuO2 by IrO2 for anodic oxygen evolution in acid media. Electrochimica acta
1986, 31 (10), 1311-1316.
New Direct Alcohol and Hydrogen Fuel Cells for Naval and Aeronautical Applications (PILCONAER)
Authors: Mosa Jadra , del Rio Carmen , Morales Enrique , Raso Miguel A. , Leo Teresa J. , Maellas Jesús , Aparicio Mario , Moreno Berta , Chinarro Eva 
Published: February 2020

In the current context of demand for reliable, low cost and low environmental impact energy sources, many countries and companies are mostly focused on fuel cells (FC) in fields as transportation and stationary power generation and portable devices. Lately, FCs have begun to be applied in naval and aeronautical systems due to its high efficiency, low noise and environmental advantages. These applications could range from propulsion systems to auxiliary power units (APU). The main problems associated with the use of FCs in these areas are the current high cost due to the materials used, i.e. Nafion and Pt, the lack of durability testing in these specific conditions, security issues to flammability and high H2
pressures and low availability as a fuel, or the toxicity of methanol used as a fuel, and specific parameters such as weight in aircraft applications and volume in marine applications. Currently it is working on each of these issues, and at this point the ethanol as direct fuel is considered crucial. The use of ethanol as fuel has the advantage of easy transportation, storage and refueling, and is nontoxic. Bioethanol is a promising energy source, produced from raw materials containing sugar or starch. These raw materials exists in all parts of the world and is renewable, which involves the use of local energy sources contributing to the diversification of energy supply, reducing import dependence, increasing security of supply and generating new opportunities for agriculture.
The main objective of the proposal is the development of low power stacks (stacks) fed with methanol (DMFC) and ethanol (DEFC) based on the development of new catalysts and membranes. The materials are considered first from the point of view of application in FCs fed with H2 (PEMFC) to be optimized and used on FCs fed directly with alcohols. An important particular objective is the development of cells fed with ethanol in alkaline medium in order to eliminate the use of Pt as the catalyst and increase the efficiency of the electrochemical FC while cost is decreased. The proposed development of new FCs fed with alcohols, especially ethanol, is considered a technology of sustainable use, further commitment to the restoration of the natural environment and biodiversity conservation.
The consortium combines groups: skilled in synthesis and characterization of materials (CSIC); expert in the development and evaluation of FC stacks (UPM and INTA) and with the ability to develop physical and mathematical models to predict the behavior of the fuel cell equipped for the MEAs fabricated (UCM). Four companies have shown interest in the proposal, as well as participation according to preliminary results.
Comments on the Problem of Metal Ions Crossing through the Cations Membrane Electrolyte in Electrolysers and Redox Flow Cells
Authors: Reda Mahmoud R. 
Published: February 2020

Redox flow Cells and hydrogen produced electrolysers are important green source of energy of the future. These cells can be activated to store energy (redox flow cells) and produce CO free hydrogen (electrolysers) by solar, wind or sea wave’s energy. In this Redox flow batteries and electrolysers a cations exchange membrane (e.g. Nafion from Du Point a cations exchange membrane selective to cations only) is used to separate the anodic regions from the cathodic regions. It is observed experimentally that during operations of these cells metal ions crosses from one region of the cell to the other which greatly lowers the efficiency of the process (irreversible capacity loss). This problem was partially solved in the case of Fe (II)/Fe(III) and Cr(II)/Cr(III) redox flow battery by utilizing the condition of electro-neutrality[1,2].The idea of mixed electrolyte introduced by Hagedorn [1] from NASA is based is using mixed cations in both anodic and cathodic regions so that during operation of the Fe (II)/Fe(III) and Cr(II)/Cr(III) redox flow cells the cations get reduced or oxidized instead of crossing the membrane and the condition of electro-neutrality is satisfied. The purpose of this publication is to generalize the application of the condition of electro-neutrality to other redox flow batteries and electrolysers and to give simple mathematical modeling of this effect [3].
[1] Introduction of mixed reactants, elevated temperatures and additive electrocatalysts NASA TM-83401.
[2] Gahn, R. ; Hagedorn, N.; and Ling, J. S.: Single Cell Performance Studies on the Fe/Cr Redox Energy Storage System Using Mixed Reactant Solutions at Elevated Temperature. Proceedings of the Eighteenth Intersociety Energy Conversion Engineering Conference, AIChE, 1983, pp. 1647-1652.
[3] Rakib et al., Journal of Applied Electrochemistry 29: 1439, 1999.
Fuel Cell Diagnostics through Neutron Imaging
Authors: Boillat Pierre , Oberholzer Pierre , Biesdorf Johannes , Schmidt Thomas J. 
Published: February 2020

The operation of polymer electrolyte fuel cells (PEFC) at high current density is of high importance in order to minimize the total stack area – an in consequence the system cost – for a given output power. At high current density, mass transport losses can become an important limitation, in particular in relation with the accumulation of water in the fuel cell porous layers. In this context, the visualization of liquid water in operating fuel cells has been extensively applied (e.g. (1-7)) in the last decade. Among the different visualization methods available, neutron imaging features the unique combination of being non-invasive (due to the transparency of fuel cell materials and the absence of radiation damage to the cell) and providing an excellent contrast for liquid water. However, unravelling the relation between water accumulation and mass transport losses cannot be done without combining visualization with advanced electrochemical characterization methods.
In a first part, the recent advances at PSI in neutron imaging and combined diagnostics methods will be presented. The advantages and limitations of mass transport characterization methods such as electrochemical impedance spectroscopy (EIS), limiting current density and our recently developed pulsed gas analysis (PGA) (5) will be presented. Additionally, the choice of test cell hardware and its impact on results from these methods will be discussed.
In a second part, a selection of experimental results will show how the combination of imaging and advanced electrochemical characterization can bring a new understanding to the mass transport limiting processes. A particular attention will be given to the choice of gas diffusion layer (GDL) material characteristics such as the amount of hydrophobic coating and the presence of a microporous layer (MPL).
1. R. Satija, D. L. Jacobson, M. Arif and S. A. Werner, J Power Sources 129, 238 (2004).
2. J. P. Owejan, J. J. Gagliardo, J. M. Sergi, S. G. Kandlikar and T. A. Trabold, Int J Hydrogen Energ, 34 3436 (2009).
3. D. Kramer, J. B. Zhang, R. Shimoi, E. Lehmann, A. Wokaun, K. Shinohara and G. G. Scherer, Electrochim Acta 50, 2603 (2005).
4. A. B. Geiger, A. Tsukada, E. Lehmann, P. Vontobel, A. Wokaun and G. G. Scherer, Fuel Cells 2, 92 (2003).
5. P. Boillat, P. Oberholzer, A. Kaestner, R. Siegrist, E. H. Lehmann, G. G. Scherer and A. Wokaun, J Electrochemical Soc 159, F210 (2012).
6. P. Oberholzer, P. Boillat, R. Siegrist, R. Perego, A. Kastner, E. Lehmann, G. G. Scherer and A. Wokaun, J Electrochemical Soc 159, B235 (2012).
7. J. Biesdorf, P. Oberholzer, F. Bernauer, A. Kaestner, P. Vontobel, E. H. Lehmann, T. J. Schmidt and P. Boillat, Phys Rev Lett 112, 248301 (2014).
Figure caption:

Figure 1 – Top: Neutron radiograms of a differential fuel cell operating at 1 A/cm2 with different humidities. Bottom: corresponding transport losses measured using our PGA method. Reproduced from ref. (5).

Figure 1
Production of Hydrogen and Chemicals from the Electroreforming of Renewable Alcohols
Authors: Miller Hamish Andrew , Vizza Francesco , Bevilacqua Manuela , Lavacchi Alessandro , Bellini Marco , Chen Yanxin , Wang Lianqin 
Published: February 2020

The exploitation of hydrogen in fuel cells is widely advocated as the ideal solution for an energetically and environmentally sustainable future for transportation. An essential part of such a solution will be the use of renewable energy resources (photovoltaics, wind, wave power etc.) in conjunction with water electrolysis to provide a “zero emission” source of hydrogen. Water electrolysis is a well-established commercial technology; nevertheless its practical application for the mass production of hydrogen is still limited mainly due to costly electrical energy consumption.
Both Alkaline and PEM electrolyzers exploit water splitting, evolving hydrogen at the cathode and oxygen at the anode. The standard reaction potential for this process is 1.23 V, meaning that water splitting is a strongly uphill reaction. In practice to get current densities in the range of 1 A cm-2 the cell potential usually ranges between 1.6 and 2 V. Considering 1.8 V as a reasonable average, we conclude that 68.3% of the energy input is consumed by thermodynamics, while kinetic factors account for only 31.7%.
Replacing anodic oxygen evolution with the oxidation of much more readily oxidizable species leads to a significant reduction of the potential required to produce hydrogen. Following this strategy compounds such as ammonia, methanol, ethanol, glycerol and urea have been tested. These electrolytic processes that lead also to the concomitant generation of chemicals at the anode and hydrogen at the cathode are often indicated as “Electrochemical Reforming”.
While undoubtedly promising, these approaches suffer the limitation of delivering current densities well below 1 A cm-2, and as such are unpractical for technological exploitation. Here we propose to overcome such limitations using a range of nanostructured anode electrocatalysts which combine fast electrode kinetics for alcohol electrooxidation with tunable selectivity for the formation of partially oxidised intermediates of industrial interest. We demonstrate that electrochemical reforming can occur at current densities comparable to that of state of the art PEM water electrolysis. Furthermore we report a net energy analysis of hydrogen production by bio-ethanol electrochemical reforming. Particularly, we define the energy cost break-even point, expressed in terms of the Energy Return of the Invested Energy of bio-ethanol production, at which electrochemical reforming becomes more energy efficient than water electrolysis.
Modelling of Proton Density Distribution in Active Nanopores of Fuel Cell Catalyst Layers
Authors: Muzaffar Tasleem Ahmad , Eikerling Michael 
Published: February 2020

Proton density and mobility in porous electrodes determine the proton conductivity as well as the rates of interfacial electrochemical processes. In the case of polymer electrolyte fuel cells (PEFCs), the foremost practical objective is to design porous electrodes or catalyst layers with high performance at markedly reduced platinum loading. Achieving this objective demands an understanding of the impact of composition and porous structure as well as surface structure and charging properties of pore walls on the proton density distribution
1
. In the presented work, we consider simple pore geometries to study the concerted effects of ionomer structure and metal charging properties on proton density in nanopores. The approach employs Poisson-Nernst-Planck theory
2, 3
. The basic model system is a cylindrical pore confined by an ionomer shell. The core to consist of a solid metal rod and the gap space between the core and the ionomer shell is filled with water. The set of ordinary differential equations for proton density and reaction in these model structures is formulated and solved. Solutions are analysed by comparing potential and proton density distributions for varying pore geometries and charging properties at interfaces. The effectiveness factor of catalyst utilization is calculated to evaluate the electrocatalytic performance at the pore level
4, 5
.
References

[1] A.Weber et al., J. Electrochem. Soc. 161(12), (2014), F1254-F1299
[2] R.Coalson and M.Kurnikova, Biological membrane Ion channels, Chap 13, Springer, NewYork (2001)
[3] K.Chan and M.Eikerling, J. Electrochem. Soc. 158(1), (2011), B18-B28.
[4] K.Chan and M.Eikerling, J. Electrochem. Soc. 159(2), (2012), B155-B164
[5] A.Bonnefont, F.Argoul, and M.Z.Bazant, J. Electroanal. Chem., 500, 52, (2011
Understanding the Limitations of Solid-State Lithium Batteries for Electric Vehicles
Authors: Ji Yan , Srinivasan Venkat 
Published: February 2020

The market penetration of electric vehicles is hindered by their safety issues and limited driving range, due to the intrinsic instability of liquid electrolytes as well as the low capacity of insertion materials used in lithium-ion technology. Solid electrolyte, including solid polymer electrolyte, inorganic solid electrolyte as well as hybrid electrolytes, provide a solution to these barriers owing to the promise of better safety and the compatibility with Li metal (higher energy density).
In the past several decades, tremendous efforts have been made to increase the ionic conductivity of the solid electrolytes. However, it is still not clear if the properties of presently available solid electrolytes are sufficient to meet the targets for electric vehicle batteries. Therefore, there is a need to correlate the electrolyte properties at the material level to battery targets at the cell and system level.
In this study, we present a material-to-cell level analysis of solid electrolytes. Continuum electrochemical models are used to project energy and power capabilities of solid-state cells based on their material properties. The models use appropriate material properties, where available, and compared to experimental data to ensure validity. The validated model is then used to estimate the cell-level energy and power capability following the testing protocols targeting electric vehicles application. This analysis helps to identify existing challenges and provides guidelines for research at both material and cell levels for this promising class of next-generation batteries.
Systematic Analysis on Ionic Conductivity of LiBH4 Infiltrated into Mesoporous Scaffolds
Authors: Choi Yong Seok , Oh Kyu Hwan , Cho Young Whan , Lee Young-Su 
Published: February 2020

It has been known that LiBH4 has a hexagonal crystal structure with a high ionic conductivity (~ 10-3 S/cm) above ~ 110 ℃, although it undergoes a reversible phase transformation to an orthorhombic crystal structure with a low ionic conductivity (~ 10-8 S/cm) below the phase transition temperature. So, many researchers attempted to extend the stability region of the high temperature phase up to room temperature by making a solid solution of LiBH4 and lithium halides. Another route to increase the ionic conductivity of LiBH4 is nanoconfinement. The confinement of LiBH4 in the mesoporous scaffolds amorphizes the structure raising the ionic conductivity as high as ~ 10-4 S/cm even at room temperature. However, it is still unclear which mechanism, i.e. nanoconfinement or generation of interface between LiBH4 and SiO2, governs the ionic conductivity enhancement of infiltrated LiBH4.
We therefore systematically investigate the ionic conductivity of LiBH4 and a mesoporous silica (here MCM-41) composite system. In order to separate the effect coming from nanoconfinement and interface, as-purchased MCM-41 was hand-mixed with LiBH4 in one case while in the other case mesopores of MCM-41 was intentionally destroyed by high-energy ball-milling. Interestingly, ionic conductivity of ball milled LiBH4 – MCM-41 mixture turned out to be ~ 10-5 S/cm, which is smaller than that of LiBH4 infiltrated into MCM-41 but it is 1000 times higher than that of pure LiBH4. The result highlights the importance of interface effect and indicates that significant enhancement in ionic conductivity can be achieved through interface engineering. To further exploit the interface effect, volume fraction of LiBH4 was systematically varied, and other kinds of compounds were tested. We believe that such approach can be useful for designing a fast ionic conductor for lithium ion battery.