bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improvement of the Cycling Performance of Sulfur Cathode Active Materials By Dual-Conducting Polymer Coating
Authors: Lee Yoon-Sung , Jeong Tae-Gyung , Jung Hun-Gi , Chung Kyung-Yoon 
Published: February 2020

Lithium-ion batteries (LIBs) as highly efficient energy storage devices have been utilized as large capacity power sources in various devices. The conventional LIBs rely on intercalation compounds as cathode materials, which have limited specific energy density of 150-200 Wh kg-1. However, the advent of electric vehicles and other high energy density applications require vast improvement in the energy density of current LIBs, which led to the search for cathode materials based on non-intercalation chemistries. Sulfur cathode is quite attractive for high energy density applications due to its advantages such as high specific theoretical capacity of 1675 mAh g-1, low cost, natural abundance, and environmental friendliness. Therefore, sulfur is considered as a promising high energy density cathode material for the next generation lithium-ion batteries. However, the poor cycle life of lithium-sulfur (Li-S) batteries due to the critical problems such as large volumetric expansion of sulfur upon lithiation, low ionic and electronic (5×10-30 S cm-1) conductivities and dissolution of lithium polysulfide into the electrolyte has been a significant hindrance for their commercialization. Recently, significant efforts have been paid to improve the cycling performance of Li-S batteries by suppressing the dissolution of polysulfide from sulfur active material and preventing the shuttling of lithium polysulfides to the anode side. Moreover, lithium polysulfide leads to serious lithium anode corrosion resulting in low coulombic efficiency. To solve these problems, extensive studies have been carried out by surface coating of cathode active materials with conductive polymers such as poly(3,4-ethylenedioxythiophene) (PEDOT), polypyrrole (PPY), and polyaniline (PANI). Surface modification of cathode active materials with conductive polymers is easy and effective way to enhance their electronic conductivity, thermal stability and electrochemical properties. Recently, we demonstrated that the cathode material coated with dual-conductive polymer can exert a significant influence on the cycling performances of lithium-ion batteries [1,2]. In the current work, we report the enhanced cycling performance and high rate performance of sulfur active cathode materials by surface modification with dual-conductive polymeric materials. The presence of protective conductive layer formed on the cathode suppresses the dissolution of lithium polysulfides on the cathode side resulting in more stable cycling characteristics when compared with those of pristine cathode material. Detailed synthesis procedure, characterization of the materials and electrochemical performance will be presented.
References
[1] S. H. Ju, I. –S. Kang, Y. –S. Lee, W. K. Shin, S. Kim, K. Shin, D. -W. Kim, ACS Appl. Mater. Interfaces., 6, 2546-2552 (2014).
[2] Y. -S. Lee, J W. K. Shin, A. G. Kannan, S. M. Koo, D. -W. Kim, ACS Appl. Mater. Interfaces., 7, 13944-13951 (2015).
(Invited) Three Dimensional Microstructure Measurements of SOFCs: Electrode Microstructural Evolution and Long-Term Durability
Authors: Barnett Scott A , Kennouche David , Wang Hongqian 
Published: February 2020

Quantitative three-dimensional (3D) analysis of solid oxide fuel cell (SOFC) electrode microstructure has been shown to be a key means for connecting materials processing and electrochemical performance. In addition, 3D imaging is being used to help observe and understand degradation mechanisms, important for developing degradation models that can predict long-term cell stability. This paper will describe 3D electrode tomography measurements, of various electrodes including Ni-Y-stabilized Zirconia (Ni-YSZ), (La,Sr)MnO3-YSZ, and (La,Sr)(Fe,Co)O3 (LSCF), made using focused ion beam scanning electron microscopy and transmission x-ray microscopy. Results on electrode structural evolution, and how the microstructure impacts electrochemical performance, will be described. For the Ni-YSZ case, measured particle coarsening during high-temperature ageing is correlated with decreases in three-phase boundary density and increases in polarization resistance and a model developed to predict long-term degradation. For LSCF, depending on ageing time and temperature, either particle coarsening or SrO surface segregation can impact electrode performance degradation.
Infiltrated CsH2PO4-Carbon Nanotube Composites for High Performance Solid Acid Fuel Cathodes with Low Pt Loading
Authors: Papandrew Alexander B. , Elgammal Ramez Ahmed , Tian Mengkun , Dyck Ondrej , Tennyson Wesley Daniel , Armstrong Beth L , Duscher Gerd , Veith Gabriel M , Zawodzinski Thomas A. 
Published: February 2020

Fuel cells based on the inorganic proton conductor CsH2PO4 (CDP)1 have the potential to be efficient devices for intermediate-temperature (230-260 °C) distributed generation applications2. Realizing this potential is contingent on the development of next-generation electrodes with significantly higher activity and lower precious metal content than the state of the art.
Current SAFC electrodes are based on a porous framework of the CDP electrolyte functionalized with an interconnected film of platinum nanoparticles that serves as both the ORR catalyst and the electronic conductor3. The activity of these electrodes scales with the surface area of the electrolyte in the electrode2, but the requirement of a percolating Pt network also unfavorably scales the precious metal content of these high surface area electrodes.
We have addressed this problem by developing a new electrode concept based on a multi-step, multiphase infiltration strategy. The CDP electrolyte is first infiltrated in the liquid phase into chemically-treated multi-walled carbon nanotube (MWNT) bundles, followed by vapor-phase Pt deposition on the nanocomposite structure. In addition to exerting a structural templating influence on the solid electrolyte, the role of electronic conduction is assumed by the MWNTs, allowing for much greater tri-phase boundary densities to be obtained at lower Pt content.
Cathodes formed from these nanocomposite materials can exceed the activity of the state-of-the-art cathode (2.8 mgPt/cm2) at a fraction of the Pt content (0.7 mgPt/cm2) (see Figure 1a). Pt utilization is increased at lower Pt loadings, with Pt mass-specific activity greater than 1 A/mgPt at 0.5 V possible at 0.35 mgPt/cm2 (Figure 1b). Cells based on this architecture are stable for greater than 150 hours at 0.6 V and 250 °C.
Acknowledgments
This work is supported by ARPA-E via cooperative agreement DE-AR0000499.
References

1 S.M. Haile, C.R.I. Chisholm, K. Sasaki, D.A. Boysen, and T. Uda, Faraday Discuss. 134, 17 (2007).

2 C. R. I. Chisholm, D. A. Boysen, A. B. Papandrew, S. K. Zecevic, S. Cha, K. A. Sasaki, Á. Varga, K. P. Giapis, and S.M. Haile, Electrochem. Soc. Interface 18, 53–59 (2009).

3 A. B. Papandrew, C. R.I. Chisholm, R. A. Elgammal, M. M. Özer, and S. K. Zecevic, Chem. Mater. 23, 1659–1667 (2011).

Figure 1
Non-PGM ORR Catalysts Based on Transition Metals Alternative to Iron
Authors: Martinez Ulises , Holby Edward F. , Dumont Joseph H , Chung Hoon T , Zelenay Piotr 
Published: February 2020

Non-platinum group metal (non-PGM) catalysts with high volumetric activity and low hydrogen peroxide yields are potential replacements for platinum-based catalysts for the oxygen reduction reaction (ORR). State-of-the-art non-PGM ORR catalyst synthesized from dual nitrogen precursors (cyanamide and polyaniline) have been presented before by our group [1]. These complex heterogeneous catalyst systems are formed from high-temperature synthesis of nitrogen, carbon, and transition metal precursors. Although Fe-N-C catalysts have demonstrated high ORR activity and low peroxide yields, Fenton (Fe2+/H2O2) and Fenton-like (Fe3+/H2O2) reactions generating hydroxyl radicals are a great concern for the durability of polymer electrolyte fuel cells due to membrane degradation. In an effort to mitigate these risks, development of iron-free non-PGM catalysts with similar ORR activity to the Fe-N-C system but enhanced durability, alternative transition metal precursors are being pursued. In this presentation, we will present further development of the dual nitrogen precursor synthesis approach replacing Fe with precursors of alternative transition metals: Co, Mn, and Ni. A systematic approach to compare structural and electrochemical characterization of all Me-N-C systems (Me = Fe, Co, Mn, Ni) will be developed for better understanding and further optimization of alternative-metal non-PGM ORR catalysts.
Furthermore, atomic-scale structures of simplified Me-Nx active site(s), obtained from density functional theory (DFT), aiding in the synthesis of non-PGM catalysts with high concentration of active site (those with simultaneously high ORR activity and practical stability), will be presented. Relative formation energies serving as descriptors of active-site structure stability will be calculated via DFT with uniform atomic reference states. Previously, O-binding had been utilized as an activity descriptor for ORR catalysts [2], but for non-PGM catalysts, OH-binding is often the potential determining step in the ORR reaction pathway. Thus, this study will present the ORR activity of simplified Me-Nx structures on zig-zag edge of graphene nanoribbons, providing a comparison of both *OH-coordinated and uncoordinated structures and predicting the ORR activity trends from such alternative metal sites to those of iron.

Acknowledgement

Financial support for this research by DOE-EERE through Fuel Cell Technologies Office is gratefully acknowledged.
[1] Chung, H.T., Holby, E.F., Purdy, G.M., Babu, S.K., Litster, S., Cullen, D.A. More, K.L., Zelenay, P. (2015). “Combining Nitrogen Precursors in Synthesis of Non-Precious Metal ORR Catalysts with Improved Fuel Cell Performance.” ECS Meeting Abstracts, MA2015-02 (37), 1278.
[2] Norskov, J.K., Rossmeisl, J., Logadottir, A., Lindqvist, L., Kitchin, J.R., Bligaard, T, Jónsson, H. (2004). “Origin of the Overpotential for Oxygen Reduction at a Fuel-Cell Cathode.” The Journal of Physical Chemistry B, 108 (46), 17886-17892.
Electrochemical Conversion of Cis,Trans-muconic Acid to Trans,Trans-muconic Acid and Trans-3-Hexenedioic Acid for Bio-Based Polymer Production
Authors: Matthiesen John Edward , Carraher Jack M , Vasiliu Monica , Dixon David A , Tessonnier Jean-Philippe 
Published: February 2020

The production of biorenewable chemicals has significantly evolved over the past years and numerous processes either have reached commercial stage or are close to commercialization.1 Recently, the biological synthesis of diacids has been receiving greater attention for the manufacture of green polyesters and polyamides.2 Muconic acid, an unsaturated C6 diacid, is quickly evolving as a high interest intermediate for the production of a wide variety of renewable chemicals from biomass (Fig. 1). The increased interest is due to the increasing market size of adipic acid and the need for greener synthesis.
Electrocatalytic hydrogenation (ECH) represents a promising approach to combine the fermentative synthesis of muconic acid with its chemical catalytic diversification to produce these value-added chemicals. ECH typically proceed by applying a -0.3 to -1.8 V potential vs. Ag/AgCl on a transition metal electrode. In contrast to high pressure hydrogenations using noble metals, the electrocatalytic hydrogenation of muconic acid is facilitated through the reduction of protons on the surface of base metal catalysts, yielding interesting selectivities and conversion rates. We demonstrate that the use of Earth-abundant catalysts such as Pb also mitigate the necessity to separate amino acids from the fermentation broth that have been shown to readily poison archetypical hydrogenation catalysts such as Ni, Pd, and Pt3.
Herein we screen a wide variety of early, late, and post transition metal catalysts in an attempt to identify key parameters that govern ECH selectivity and faradaic efficiency. In particular, we differentiate the selected transition metals based on the free energy of hydrogen absorption ΔGH on ECH performance (Fig. 2). Our studies detail the synthesis of trans,trans-muconic acid and trans-3-hexenedoic acid, two bio-based intermediates for the production of polyamides and polyesters, using low hydrogen overpotential metal catalysts. In contrast, high hydrogen overpotential metals produced trans-3-hexenedioic acid with high yield and faradaic efficiency. Conversion and selectivities after 1 h reaction durations for two particular electrocatalysts are displayed in table 1. In all cases, the need to identify binding strengths of the organic reactant will necessitate further correlations that determine hydrogenation product selectivity.

References

1. Choi, S.; Song, C. W.; Shin, J. H.; Lee, S. Y. Metab. Eng.
2015,28, 223-239.
2. Becker, J.; Lange, A.; Fabarius, J.; Wittmann, C. Curr. Opin. Biotechnol.
2015,36, 168-175.
3. Schwartz, T.; Brentzel, Z.; Dumesic, J. Catal Lett
2015,145, 15-22.
4. Greeley, J.; Jaramillo, T. F.; Bonde, J.; Chorkendorff, I.; Norskov, J. K. Nat. Mater.
2006,5, 909-913.
5. Trasatti, S. J. Electroanal. Chem. Interfacial Electrochem.
1972, 39, 163-184.

Figure 1
Mushroom-Derived Flow Battery Electrolytes
Authors: Cappillino Patrick J , Huang Haobo , Wheeler Joseph , Howland Rachael 
Published: February 2020

There is a strong and growing need for reliable, cost-effective grid storage to support a transition from fossil fuels. Non-aqueous redox-flow batteries (NRFB) are a promising technology to meet this need but they are currently limited by poor stability of solution-phase, charge-carrying metal complexes. A major mechanism of decomposition of these redox electrolytes is substitution of ligands that have weak interactions with substitution-labile metal ions. Presented herein is an approach to mitigate these thermodynamic and kinetic challenges with a naturally occurring compound that is produced biologically. Mushrooms of the genus Amanita synthesize a molecule known as Amavadin, in which a vanadium ion is tightly coordinated by a pair of 2,2’-(hydroxyimino)dipropionic acid (HIDPA) ligands. Millions of generations of evolution have optimized the stability of this molecule. As a result, under physiological conditions in which most vanadium compounds would decompose, ligand substitution is suppressed.
The electrochemical properties of redox molecules based on Amavadin as NRFB electrolytes will be presented. This will include data on electrochemical reversibility and stability to deep redox-cycling under various conditions. In addition, we will present the results of computational investigations that have guided ligand-design efforts. These are focused on optimization of the properties of Amavadin-based compounds for application in energy storage devices without losing their extraordinary ability to bind metal ions.
(Invited) Α-Mn2O3 Electrodes for the Oxygen Evolution Reaction - Catalytic Activity As a Function of Electrode Preparation
Authors: Fiechter Sebastian , Kölbach Moritz , Kratzig Andreas , Hillebrand Philipp , Ramirez-Caro Alejandra , Ellmer Klaus , Bogdanoff Peter 
Published: February 2020

In photosynthesis nature uses transition metal complexes as catalysts to evolve oxygen and hydrogen from water. In this process the catalytic centers are separated from the light capturing and absorbing co-factors in photosystem I and II integrated in the thylakoid membrane. To develop bio-inspired catalysts and to mimic e.g. the Mn3CaO3MnO complex in PSII, different manganese oxides as well as alkaline metal and earth alkali metal manganates were investigated with respect to the oxygen evolution reaction (OER) in the process of water oxidation. In this contribution special attention will be turned to the structure - morphology– function relationship of these materials.
Manganese oxide electrodes have been prepared by reactive magnetron sputtering from a Mn target in an Ar/O2 atmosphere as well as by anodic electrodeposition and a subsequent annealing step. Besides amorphous MnOx obtained at low temperatures, crystallized oxides, such as γ-MnO2 and α-Mn2O3, were tested as electrocatalysts. Thin (60-70 nm) and dense layers were deposited by reactive magnetron sputtering using conductive glass (FTO) slides as substrates. Cross section transmission electron micrograph (Figure 1a) clearly revealed that the sputtered α-Mn2O3 layers consist of nanocrystals of
10 - 20 nm edge length. These layers show current densities of 10 mA/cm-2 at an overpotential of 370 mV (pH 13.8). Similar overvoltages were also obtained with electrodeposited α-Mn2O3 layers (10mA/cm-2 at 340 mV overvoltage). In contrast, the electrochemically deposited α-Mn2O3 layers are several 100 nm thick and appear highly porous (Figure 1b). Obviously, the specific activity related to the active surface area of the sputtered material is about one order of magnitude higher than the one of the electrodeposited samples. Nevertheless, higher current densities can be achieved with the electrodeposited material because high electrochemically active surface areas can be provided.
This behavior will be discussed as a function of defect chemistry and will be compared with the structure – function relationship of other OER electrocatalysts.
References
[1] A. Ramírez, P. Hillebrand, D. Stellmach, M. May, P. Bogdanoff, S. Fiechter; J. Phys Chem. C, 118 (2014) 14073-14081 and SI.
[2] M.M. Najafpour, T. Ehrenberg, M. Wiechen, P. Kurz; Angew. Chem. Int. Ed., 49 (2010) 2233-2237.
Figure 1: α-Mn2O3 deposited a) by reactive magnetron sputtering and b) by electrochemical deposition.

Figure 1
Experimental Analysis of Thermal Runaway in 18650 Cylindrical Li-Ion Cells Using an Accelerating Rate Calorimeter
Authors: Lei Boxia , Ziebert Carlos , Zhao Wenjiao , Melcher Andreas Markus , Rohde Magnus , Seifert Hans Jürgen 
Published: February 2020

In this work commercial 18650 lithium ion cells with LiCoO2 and LiMn2O4 cathodes were exposed to external heating in an Accelerating Rate Calorimeter (es-ARC, THT Company) in order to investigate the thermal behavior under abuse conditions.
During the experiments the temperature and the internal pressure changes of the cells were measured in the ARC. Furthermore, external pressure changes were measured in order to detect venting of the cells. Before the measurement the cells were fully charged and the so-called Heat-Wait-Seek method was applied. This procedure starts by heating the sample in small incremental steps. At the end of each step the calorimeter “waits” if the battery is generating heat that can be measured by a temperature rise (so called "seek" step). When self-heating of the cell is detected, the ARC switches to the adiabatic mode in which the temperature of the calorimeter follows instantaneously the surface temperature of the cell, i.e. the cell cannot exchange heat with the surroundings anymore. This procedure is repeated until a thermal runaway occurs. For the external pressure measurements, the cell was placed in a gas-tight cylindrical compartment inside the calorimeter chamber. This compartment was equipped with an outlet where a pressure line is connected with a pressure sensor. In contrast to the external pressure measurement for internal pressure measurements this pressure line was directly inserted into the cell. Therefore, a suitable place had to be found by using images from X-Ray Tomography. In a second experiment a current profile was applied to the cell with maximal C-rate and cycled until a thermal runaway occurs. During these experiments again the internal and external pressure was measured as well as the cell temperature. In addition the heat capacity was measured to calculate the heat of reaction.
From the results of the thermal runaway experiments, three stages (low rate reactions stage, medium rate reactions stage and high rate reactions stage) have been observed. Both pressure and temperature change indicated different stages of exothermic reactions, which would produce gases or/and heat. The onset temperature of thermal runaway was estimated according to temperature and pressure changes in the measurements. Moreover, the different activation energies for the exothermic reactions could be derived from Arrhenius plots.
Finally, the experimental data were compared with the results of numerical simulations based on an electrochemical-thermal model which was extended with additional source terms in order to describe the exothermic reactions inside the cell during thermal runaway. The experimentally determined activation energies have been used as input parameters for these simulations. It could be shown that the above mentioned reactions stages can also be found in the simulations.
Electrochemical Studies of Halogens at Carbon Graphite Electrode in Aqueous Solutions
Authors: Quintero Pulido Diego Fernando , Ten Kortenaar Marnix Victor , Hurink Johann , Smit Gerard 
Published: February 2020

Abstract
The electrochemical behaviour of halogens redox couples is studied on carbon graphite electrode by voltammetry under different conditions (pH, Concentration, Cation and Temperature). It is found that there is a large difference in current density behaviour between the different halogen electrolytes at a concentration of 2M (I- 400mA/cm2 and Br- 250mA/cm2 oxidation peak at 1.5V) as shown in Figure 1. Besides this, it is found that changing the cation salt (e.g. NaBr and ZnBr2) affected the current density to a great extent, the effect is observed more clear when the concentration of the electrolytes are changed from 3M to 8M. This effect may be related to pH changes caused by the identity of the cation (Na and Zn). In general, the pH is found to affect oxidation of halogens substantially at pH lower than 5. In line with these results, the diffusion coefficient increases when acid is added to the electrolytes. As expected, the current density increased when temperature is raised and the activation energy have a value of 45kj/mol for the Br- oxidation at carbon graphite. Finally, It is found with UV-Vis experiments that halogen oxidation at carbon graphite shifts to a lower peak wavelength when cation is change and differs from pure halogen spectra.
Key words: Halogens, Voltammetry, graphite

Figure 1