bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation into the Solvation of Lithium Anions and the Search for a Connection with Electrode Passivation Behavior
Authors: Cresce Arthur v. , Xu Kang , Russell Selena M. , Urban Nathaniel , Wikner Emily 
Published: February 2020

Abstract:
Recently published studies have shown that there is a complex relationship between a lithium ion and its solvent molecules in two-solvent electrolyte systems. Cyclic carbonates like ethylene carbonate are stable in the Li+ solvation sheath while linear carbonates like dimethyl carbonate move in and out frequently, reflecting a difference in coordinating stability with Li+. Because of this bias in Li+ coordinating ability, a correlation can be drawn between the composition of the Li+solvation sheath and the resulting composition of the passivating solid electrolyte interphase that forms on the graphitic anode of a Li-ion battery during the first charge.
We are investigating the solvation condition of the anion in the Li-ion electrolyte system with the goal of identifying a potential correlation between the solvation condition of the anion (including PF6
-, BF4
-, ClO4
-, and TFSI-) and the formation and composition of a cathode passivation layer.
Our previous work indicated that although typical electrolyte anions are poorly coordinated, both PF6
- and BF4
- showed a preference for the low-permittivity linear carbonate ethyl methyl carbonate over the high-permittivity solvent ethylene carbonate. The PF6
-results are summarized in Fig. 1. This result spurred further investigation into the solvation condition of the anion, accomplished using electrospray mass spectrometry, linear voltammetry, x-ray photoelectron spectroscopy, and density functional theory simulations of anion-solvent cluster stability.
We will attempt to show a correlation between the stability of anion-solvent clusters with the composition and formation of the cathode interphase layer.
Verification of O2
-• Formation during Oxygen Reduction Reaction in Li-O2 Batteries
Authors: Cao Ruiguo , Walter Eric , Xu Wu , Nasybulin Eduard , Zhang Ji-Guang 
Published: February 2020

Li-O2 battery has been regarded as one of the most promising energy storage systems for the next generation of electrical vehicles and large scale stationary applications.1 It has very high theoretical energy density compared to those of other rechargeable batteries. However, the research for Li-O2 batteries so far is still in its early stage. Significant problems on the stability of electrolyte, cathode and Li anode used in Li-O2 battery still need to be solved before its practical applications.2

In this regards, selection of stable electrolytes, substrates, and efficient catalysts are at the heart of all concerns, without which the rechargeable Li- O2 batteries will not be successful. In order to search stable electrolyte and develop highly efficient catalyst and consequently improve the cycle life of the Li-O2 battery, it is necessary to have a deep understanding on the mechanism of oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in non-aqueous electrolytes. The mechanism of ORR and OER greatly depends on the activity of catalysts and the types of electrolyte solution environments. Superoxide radical anion (O2
-•) has been proposed as an intermediate during the discharge process, followed by a disproportionation reaction. However, no direct evidence has been found to prove this mechanism because the lifetime of superoxide radical is extremely short at room temperature and it is difficult to visualize the existence of O2
-• by using spectroscopic techniques. Recently, we have studied ORR and OER mechanisms in a non-aqueous Li-O2 battery using ex-situ electron paramagnetic resonance (EPR) technique and have successfully detected the formation of O2
-• during the ORR process (Figure 1). In the charging process, nearly no formation of O2
-•has been found during the OER process. Details of the investigations will be reported and discussed in the presentation.

Acknowledgements

This work was supported by the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the Basic Energy Sciences, Office of Science of the U.S. DOE. The EPR measurements were performed in the Environmental Molecular Sciences Laboratory, a national scientific user facility sponsored by the DOE’s Office of Biological and Environmental Research and located at PNNL.
1. P. G. Bruce, S. A. Freunberger, L. J. Hardwick and J.-M. Tarascon, Nat Mater, 2012, 11, 19-29.
2. Y. Shao, F. Ding, J. Xiao, J. Zhang, W. Xu, S. Park, J.-G. Zhang, Y. Wang and J. Liu, Adv Funct Mater, 2013, 23, 987-1004.
Development of a High Temperature PEO-Based Li Air Battery
Authors: Balaish Moran , Ein-Eli Yair 
Published: February 2020

Li-air battery has the potential of becoming the ultimate power source among all electrochemical energy conversion and storage configurations derived from lithium chemistry. Unfortunately, current configurations, mostly based on a non-aqueous organic liquid electrolyte, suffer from numerous challenges, namely high electrolyte volatility, electrolyte decomposition, low cycle-life, low discharge rates and high discharge/charge over-potential. A very appealing Li-air configuration is obviously one which sees the use of a solid, solvent-free, electrolyte, such as those formed by combining poly(ethylene oxide), PEO, and a lithium salt. Polymer electrolytes are well known promising materials for high energy density rechargeable batteries. Polymer electrolytes poses several advantages over liquid based electrolytes systems, in terms of high chemical, thermal and electrochemical stabilities, all of those are important factors for batteries in number of applications, ranging from portable electronics to electric vehicles. However, wide use of solid polymer electrolyte is still prevented by the decay in ionic conductivity (10-7 to 10-5 S cm-1 at room temperature), resulting from low ionic mobility, high degree of polymer matrix crystallinity, and low degree of charge separation in addition to ion association. We hereby offer a new Li-air battery configuration, based on the well-investigated PEO- lithium salt electrolyte system. The Li-air battery will be comprised of a lithium metal anode, a highly Li+ conductive, oxygen permeable PEO-based, lithium polymer electrolyte and a high surface area carbon air cathode. As opposed to current lithium polymer electrolytes, which operate at room temperature and suffer from low ionic conductivity, the new proposed configuration will operate at a high temperature of 80°c. Above 70°c PEO predominantly exists in the amorphous state, thus a practically useful conductivity is easily achievable in the temperature range of 70-95°c. Our Li-air cell is discharged/ charged at high temperature, thus enabling better kinetics, resulting in high current densities and lower over-potential. The system is studied by electrochemical methods as well as spectroscopic ones.
The results of this work will contribute to the development of practically viable Li-air batteries.
Development of New Anode Composite Materials for Fluoride Ion Batteries
Authors: Rongeat Carine , Munnangi Anji Reddy , Fichtner Maximilian 
Published: February 2020

The increasing demand for high energy storage systems has prompted the interest to alternative chemistries for new battery systems, with better performances than currently used Li-ion batteries. Recently, the reversible charge and discharge of a battery based on a fluoride shuttle has been demonstrated [1]. Such a fluoride ion battery (FIB) can theoretically achieve a high energy density, i.e. above 5000 Wh.L-1 for some electrode combinations. This type of batteries is at an early stage of development and large improvements need to be done concerning the performance of the electrodes or of the electrolyte. In the first study, different types of metal fluorides were already tested as cathode (BiF3, CuF2, SnF2 or KBiF4) and Ce metal was used as anode. However, this material, as well as other potential anode materials like La, Ca, Li or Mg, is very sensitive to oxidation, even when stored under argon. We therefore decided to prepare electrode materials in the discharged state to investigate new anode materials, using Bi metal as cathode. We found that it was possible to obtain several cycles of charge/discharge using CeF3 or doped-CaF2 as anode but not when using MgF2. Moreover, the discharge capacities obtained after the initial charge were low. To ensure both electronic and ionic conductivity in the electrodes it is usually necessary to prepare a composite material. Here, only activated carbon was added to CeF3 and doped-CaF2 as these compounds are also good ionic conductors. In the case of MgF2, it was necessary to add also a certain amount of the electrolyte as MgF2 itself shows very poor ionic conductivity. The low performances obtained for this anode composite are thus most likely linked to interfaces issues between the different compounds of the electrode composite. In order to improve the reactivity of the interfaces, a new composite was prepared by adding Mg and MgF2 (the charge and discharge products) to the electrolyte and carbon in the anode composite. Using this new anode composite, it was possible to obtain much better cycling performances with higher charge/discharge capacities and lower polarization. Different characterization techniques were used to understand the reactions occurring when using the different anode material and understand the improvement observed when mixing Mg and MgF2.
[1] M. Anji Reddy & M. Fichtner – J. Mater. Chem. 43 (2011) 17059
Theoretical Study of the Morphological and Structural Characteristics of a Hydrated Anion Exchange Membrane Used in Alkaline Fuel Cells Using DFT
Authors: Castañeda Ramírez Sergio , Ribadeneira Paz Rafael Esteban 
Published: February 2020

Anion-exchange membrane fuel cells (AEMFC) have great potential of commercialization at low cost for their use in automotive transportation, portable batteries and power generators with respect to similar technologies as the proton-exchange membrane fuel cells (PEMFC) due to: a) better kinetic characteristics both for the oxygen reduction reaction as for the hydrocarbon oxidation reducing costs of catalysts, b) lower fuel crossover from anode to the rest of the device, c) simpler water management and d) reduced degree of corrosion [1–3].
Despite the mentioned advantages, the polymeric materials used as electrolytes show low conductivity and chemical stability values, which limit respectively the efficiency and durability of the fuel cell, and as experimentally these factors have not been optimized yet, it is important to understand the related physicochemical phenomena, being the anion transport primordial [1,2,4,5]. Nevertheless, the characteristics of the mechanisms associated with that process are not well known, particularly the Grotthuss mechanism, that is considered to contribute mostly to the hydroxyl ion mobility [1,4].
In order to understand this mechanism and to improve the description of the ion mobility in AEMFCs is mandatory to carry out a rigorous theoretical study, for which the first step is to describe the appropriate structure of a particular anion exchange membrane. So, the aim of the present research is study the morphological and structural characteristics of the quaternized polystyrene-block-poly(ethylene-ran-butylene)-block-polystyrene homogeneous membrane synthetized by Qing Hua Zeng and co-workers [6] for different humidification values by means of density functional theory (DFT) techniques, considered the most suitable in terms of prediction and accuracy since there are not almost theoretical studies about structural and morphological characteristics of anion exchange materials used in AEMFC.
With the results obtained, the idea is evaluate the potentiality of DFT techniques to obtain accurate structures for polymeric membranes and use the one generated for future investigations about the physicochemical characteristics of the Grotthuss mechanism for hydroxyl ions in membranes used in AEMFCs, in order to determine the best morphological and structural characteristics of this type of materials from a theoretical approach.
References:
[1] G. Merle, M. Wessling, K. Nijmeijer, J. Memb. Sci. 377 (2011) 1.
[2] E. Antolini, E.R. Gonzalez, J. Power Sources 195 (2010) 3431.
[3] R. Slade, J. Varcoe, Solid State Ionics 176 (2005) 585.
[4] K.N. Grew, W.K.S. Chiu, J. Electrochem. Soc. 157 (2010) B327.
[5] B. Pivovar, 2011 Alkaline Membrane Fuel Cell Workshop Final Report, 2012.
[6] Q.H. Zeng, Q.L. Liu, I. Broadwell, A.M. Zhu, Y. Xiong, X.P. Tu, J. Memb. Sci. 349 (2010) 237.
Li Diffusion in Rare-Earth Metal Doped Battery Materials
Authors: Grosse Frank 
Published: February 2020

One of the key elements determining the performance in Li-ion batteries is the diffusion. All solid-state batteries require fast ionic diffusion in the electrolyte but equally important in the anode and cathode. The electrolyte is required to be electronically non-conducting, the opposite is true for anode and cathode. Various compounds are currently investigated.
It is intuitively clear that by widening the Li-ion diffusion channels the activation barrier will be reduced leading to faster diffusion. The lattice parameter can be increased by partially replacing host atoms by impurities with a larger atomic radius. With this strategy in mind, I) the influence of the diffusivity on the lattice parameter is studied employing density functional theory. II) The thermodynamic stability of rare-earth metal atoms as impurities in existing battery materials is calculated in conjunction with the Li diffusion.
I) The influence on the lattice parameter is evaluated in two ways. Changing the lattice parameter by introducing impurities or alloying similar materials not only changes the lattice parameter but simultaneously introduces disorder along the Li-ion diffusion pathways. Therefore, changing only the lattice parameter artificially by applying an external strain allows disentangling the contributions from the lattice expansion vs. the disorder effect. At the example of Li diffusion in rare-earth oxides it is shown that the activation energy can be reduced by increasing the lattice parameter in agreement with experiments [1].
II) The thermodynamic stability of rare-earth metal atoms in materials suggested as cathode materials like spinel LiMn2O4 and LiCoO2 is calculated. The influence on the Li diffusion due to the introduced lattice distortion and reduced symmetry is discussed. A coarse-grained diffusion model on the basis of the DFT data is introduced containing the relevant changes in the local activation energies due to the presence of the rare-earth metal impurities. The numerical evaluation of the diffusion is carried out by kinetic Monte Carlo simulations.

Acknowledgements: This work was supported by the Leibniz-Gemeinschaft under the project No. SAW-2011-PDI-230.
[1] S. Tamura, A. Mori and N. Imanaka (2006). Solid State Ionics, 177(26-32), 2727–2730.
Dynamics of Deposited Li2O2 Clusters on Cathode Surface in Li-O2 Battery Investigated By First-Principles Molecular Dynamics
Authors: Yamamoto Wataru , Alam Md. Khorshed , Takaba HIromitsu 
Published: February 2020

In recent years, Li-O2 battery has received a great attention as a battery with high capacity and energy density. However, further studies are needed for the use of practical application to solve the issues must be overcome, such as lithium dendrites, side reactions of electrolyte, a blocking effect of diffusion path of oxygen and a corrosion of carbon. In this study we focus on, among from these issues, a blocking effect of diffusion path of oxygen in the cathode, which is the most important issue to realized the high capacity. Discharge products would inhibit oxygen diffusion in a cathode. Main discharge product is Li2O2. In this study we also focus on a dynamics of Li2O2. Li2O2 is generated from electrochemical reaction and will cover with the surface of the cathode resulting in the termination of further electrochemical reaction. Thus, the elucidation of dynamics of Li2O2 cluster on cathode surface is a key problem for the better understand of the life time of battery and the theoretical design of more improved Li-O2 battery.
The electrical conductivity of Li2O2 is also influenced on the life time of the battery. There has been reported that a hole forming by the defect of Li palys a important role in the electrical conductivity of Li2O2. In this study, we model the formation of deposited Li2O2 layer as well as the forming process of the crystal defect, from the point of view of diffusion of Li2O2 cluster on the cathode surface. We calculate the sintering and diffusion processes of the discharge product Li2O2 on the carbon surface using a first-principles molecular dynamics method. We also examine how Li2O2 is deposited on the carbon surface. As a result, it deposited on the cluster shape up to the thickness of 3 " at 300 K. It is observed that the band gap of the Li2O2 is related to the thickness and it rapidly increases when it exceeds the 8 ". Diffusivity decreases in proportion to the increase in the size of Li2O2 cluster. Calculated diffusion coefficient of Li2O2 is revealed to the effect on the electrical conductivity of Li2O2. From these results, we investigate the effect of electrical conductivity of Li2O2 on the discharge curve analyzing by a numerical simulation. Conductivity shows little effect on the discharge curve. Therefore, It is concluded that a pore blocking is major factor of capacity of Li-O2 battery. This is the first study will be able to provide a breakthrough for the development of better Li-O2 battery.
Performance of MIEC Cathodes in SOFC Stacks Evaluated by Means of FEM Modeling
Authors: Geisler Helge , Kromp Alexander , Weber André , Ivers-Tiffée Ellen 
Published: February 2020

Solid oxide fuel cells (SOFC) are connected in series to stacks by metal interconnectors (MIC). Hereby, the potentially high performance of anode-supported cells (ASC) is significantly reduced. [1,2]. Conclusively, gas diffusion polarisation at the mixed conducting cathode contributes close to the sum of all ohmic losses to the overall polarization, both controlling stack performance.
In order to investigate the matter further, a 2D FEM repeat unit model was developed, which accounts to ohmic and polarisation loss on a stack level [3]. In the model the physical processes i) gas diffusion in the porous electrodes, ii) electric /ionic conduction in the electrodes and electrolyte as well as iii) the electrochemical electrode reactions are incorporated. Electrode microstructure is implemented via 3D reconstruction of FIB-tomography images [5,6]. Electrode kinetic parameters are determined via EIS evaluations [4]. Performance predicted by the model was validated with the help of current/voltage-characteristics measured on high performance anode supported cells.
The model calculations demonstrate the interdependence of cathode material parameters (thickness, porosity, conductivity, electrode kinetics) and MIC-design, and widen the understanding on their influence on stack performance. The results show i) that an optimal MIC-design depends on the cathode material parameters and ii) a well-chosen cathode thickness increases the overall power output.
[1] L. Blum, W. A. Meulenberg, H. Nabielek, R. Steinberger-Wilckens, Worldwide SOFC Technology Overview and Benchmark, International Journal of Applied Ceramic Technology2 pp. 482-492 (2005).
[2] M. Kornely, A. Leonide, A. Weber, E. Ivers-Tiffée, Journal of Power Sources
196 (17), pp. 7209-7216 (2011).
[3] H. Geisler, M. Kornely, A. Weber, E. Ivers-Tiffée, ECS Trans.
57, pp. 2871-2881 (2013).
[4] A. Leonide, Y. Apel, E. Ivers-Tiffée, ECS Trans.
19, pp. 81-109 (2009)
[5] J. Joos, T. Carraro, A. Weber, E. Ivers-Tiffée, J. Power Sources
196, pp. 7302-7307 (2011).
[6] J. Joos, M. Ender, I. Rotscholl, N. H. Menzler, E. Ivers-Tiffée, J. Power Sources
246, pp.819-830 (2014)
Proton-Conducting Ce0.9Mn0.1P2O7 Composite Electrolytes for Low Temperature Ceramic Electrolyte Fuel Cells
Authors: Singh Bhupendra , Kim Ji-Hye , Jeon Sang-Yun , Park Jun-Young , Song Sun-Ju 
Published: February 2020

Cerium pyrophosphate based solid state proton conducting materials with ionic conductivity >10-2 S cm-1 in 100-250 oC range have immense importance in fuel cells.1-5 In this work, Ce1-xMnxP2O7 (CMP) (x=0.05, 0.075, 0.1, 0.125 and 0.15) composite electrolytes are synthesized by two-step slow digestion method with different P/(Ce+Mn) molar ratio.4 The CMP samples with high phosphate content become denser on sintering. The variation of ionic conductivity with temperature is studied in dry and humidified air for the potential application of CMPs as electrolytes in proton-conducting ceramic electrolyte fuel cells. Among various CMP samples, CMP-100-2.7P (i.e. Ce0.9Mn0.1P2O7 with P/(Ce+Mn)=2.7) shows maximum conductivity of 6.54X10-6 S cm-1 at 450 oC in dry air and 1.78X10-2 S cm-1 at 170 oC in humidified air (pH2O= 0.12 atm). The ionic conductivity of CMPs increases with the increasing pH2O and CMP-100-2.7P shows maximum conductivity of 2.24X10-2 S cm-1 at 170 oC in pH2O=0.16 atm.
Figure. (a) SEM images of fractured section of 400 oC sintered pellets of Ce0.9Mn0.1P2O7 samples with different initial P/(Ce+Mn) ratio; Temperature dependence of ionic conductivity of various CMP samples with different dopant concentration in (b) dry air and (c) humidified air (pH2O =0.12 atm) condition.

References

B. Singh, H. N. Im, J. Y. Park, and S. J. Song, J. Electrochem. Soc.,
159, F819 (2012).

B. Singh, H. N. Im, J. Y. Park, and S. J. Song, J. Phys. Chem. C,
117,2653 (2013).

B. Singh, H. N. Im, J. Y. Park, and S. J. Song, J.
Alloys Compd.,
578, 279 (2013).

B. Singh, S. Y. Jeon, J. H. Kim, J. Y. Park, and S. J. Song, (Submitted in J. Electrochem. Soc.).

C. Chatzichristodoulou, J. Hallinder, A. Lapina, P. Holtappels, and M. Mogensen, J. Electrochem. Soc., 160, F798 (2013).
Carbonate Fuel Cell Anode: A Review
Authors: Hilmi Abdelkader , Yuh Chao-Yi , Farooque Mohammad 
Published: February 2020

Introduction
The molten carbonate fuel cell (MCFC) has emerged as one of the leading devices to convert chemical energy into power. To date 1.9 GWh of electricity has been produced commercially using this new technology. The molten carbonate fuel cell uses a mixture of alkali carbonates as the electrolyte and operates in the temperature range of 550-650°C. The high operating temperature dramatically improves the reaction kinetics and eliminates the need for a noble metal catalyst. During cell operation, hydrogen is oxidized at the anode and oxygen is reduced at the cathode, equations (1) and (2)
H2 + CO3
2- → H2O + CO2 + 2e- (1)
1/2O2 + CO2 + 2 e- → CO3
2- (2)
The current carbonate fuel cell design (illustrated in figure 1) has evolved over many years from extensive research conducted in fifteen companies and many prestigious laboratories. The cell hardware is made from stainless steel, the electrodes are nickel based, and the separator called matrix is a porous ceramic. The anode design is an important consideration from both performance and cost considerations.
The state of the art MCFC anode is a porous Ni electrode stabilized against sintering by Cr and/or Al additives. Typical anodes have porosities of 40-60% and 3-6 µm as average pore diameters. To ensure long-term stability against creep, corrosion and oxidation, major considerations need to be taken into account in material selection. Mechanical and chemical stability as well as the electrochemical activity for anode are key factors for performance and life stability.
Accelerated lab-scale technology stacks (30kW) and long-term field tests have shown that the current anode materials have the desired performance and stability of the useful life of >5-7 years. As shown in figure 2, anode maintains stable pore structure and morphology over long-term operation. Parameters such as conductivity, pore size distribution, wetting and electrolyte fill level affect anode performance and its stability. To achieve an