bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Impact of Sulphate Anions on the Catalyst Durability for PEMFC
Authors: Stamatin Serban Nicolae , Nørgaard Casper Frydendal , Andersen Shuang Ma , Skou Eivind Morten 
Published: February 2020

Platinum based nanoparticles supported on high surface area carbons still remain the most used reference for the activity and durability of fuel cell catalysts. Usually, a catalyst thin film supported on a rotating disk electrode in a liquid electrolyte is connected in a three electrode electrochemical cell setup. This has been proven to be the best technique to predict the activity and durability of a catalyst in real fuel cell [1]. It has been proven that there are differences in activity between perchloric acid and sulphuric acid [2]. Recently, it has been shown that the sulphate anions are poisoning the catalyst surface which can give rise to different degradation mechanisms then from the studies in perchloric acid [3].
Taking into consideration that different research groups are characterising catalysts in either sulphuric acid or perchloric acid and there is proof of the difference in activity, this work is focused on emphasizing the difference between durability studies in perchloric and sulphuric acid as revealed by Fig. 1. In order to determine the impact of anions on the overall degradation a series of experiments conducted in perchloric acid, sulphuric acid and half MEA have been conducted. As a measure of the durability, Pt dissolution has been monitored by AAS of the electrolyte.
Fig. 1 ESA loss vs number of cycles in 0.5 M perchloric acid (red line) and sulphuric acid (black line). The degradation took place in a two compartment - three electrode electrochemical cell and the electrode was cycled between 0.05-1.3 VRHE at 0.2 V s-1.

Acknowledgement

This work has been supported by the Danish PEMFC Catalysts for Boosted Activity and Enhanced Durability (Energinet. dk project no. 2011-1-10669).

References

[1] H. A. Gasteiger, D. R. Baker, R. N. C. Hydrogen Fuel Cells: Fundamentals and Applications; Wiley: Copenhagen, 2010
[2] Meier, J. C.; Galeano, C.; Katsounaros, I.; Topalov, A. A.; Kostka, A.; Schu, F.; Mayrhofer, K. J. J. ACS Catalysis 2012, 2, 832–843.
[3] K. Kodama, A. Shinohara, N. Hasegawa, K. Shinozaki, R. Jinnouchi, T. Suzuki, T. Hatanaka, Y. Morimoto ECS Transactions, 58 (1) 363-368 (2013)
Synthesis of 1,4-Bis(diaryl)-1,3-Butadiynes Bearing Two Amino Moieties by Electrochemical Reaction Site Switching and Their Solvatochromic Fluorescence
Authors: Mitsudo Koichi , Kamimoto Natsuyo , Nakamura Nariaki , Suga Seiji 
Published: February 2020

Recently, π-conjugated compounds have been on focus because they are known to be as key building blocks for pharmaceuticals and potent candidates for electrochemical and optical materials. While the optical and electrochemical properties of π-conjugated compounds highly depends on the structure, it has not been easy to predict these properties. It is the reason why facile and diversity-oriented methodologies to construct π-conjugated structure have been strongly required. From such a point of view, we have investigated electrochemically assisted coupling reactions for constructing π-conjugated compounds, and recently reported sequential coupling reactions which include Pd/Cu-catalyzed electro-oxidative homo-coupling of p-bromophenylacetylene to give 1,4-bis(p-bromophenyl)-1,3-diyne and subsequent Suzuki–Miyaura coupling with arylboronic acids leading to 1,4-bis(diaryl)-1,3-butadiynes.1 Two reaction sites of p-boromophenylacetylene, terminal alkyne and Br group, could be discriminated in a virtually complete manner by on/off application of electricity, and we called the strategy as “Electrochemical Reaction Site Switching (e-RSS)”. Several arylboronic acids could be applied to the reactions, and the reactions proceeded selectively to give 1,4-bis(diaryl)-1,3-butadiynes in good to excellent yields.
During the course of the investigation, we unexpectedly found that 1,4-bis(diaryl)-1,3-butadiyne bearing two dimethylamino groups at p-position exhibited solvatochromic fluorescence. To the best of our knowledge, while there have been many reports on the amines which exhibit solvatochromic fluorescence, there have been few reports on the solvatochromic fluorescence of diamines which have small dipole moment. Most of the amines exhibiting solvatochromic fluorescence so far have a strong acceptor moiety. This unexpected result prompted us to get deeper insight into this unusual phenomenon; however the poor solubility of diaminodiynes prevented us from further investigation. We therefore designed novel 1,4-bis(diaryl)-1,3-butadiynes bearing two dialkylamino or diphenylamino groups at p-position of the terminal benzene rings. The butadiynes could be easily synthesized by e-RSS with the corresponding p-aminoarylboronic acids. As expected, thus obtained diynes could be solved into several solvents and they exhibited solvatochromic fluorescence. We will discuss the detail of the synthesis of 1,4-bis(diaryl)-1,3-butadiynes bearing two dialkylamino or diphenylamino groups at p-position, and their unique optical properties.
(1) Mitsudo, K.; Kamimoto, N.; Murakami, H.; Mandai, H.; Wakamiya, A.; Murata, Y.; Suga, S. Org Biomol Chem
2012, 10, 9562-9569.
Structure and Electrochemistry of Cation Substituted "Layered-Layered Composite" Cathode Materials for Li-Ion Batteries
Authors: Lee Eungje , Long Brandon R. , Croy Jason R , Balasubramanian Mahalingam , Key Baris , Maroni Victor A. , Thackeray Michael M. , Johnson Christopher S. 
Published: February 2020

Recently, Li- and Mn-rich ‘layered-layered’ composite materials have drawn much attention as possible high-energy cathode materials for next generation electric vehicles. However, continuous voltage fade (VF) during cycling has been observed with virtually all Ni-Mn-Co based compositions and understanding and arresting the VF is urgently required for its commercial application. The voltage fade is thought to be related to the instability of the composite ‘layered-layered’ structure. Such structural relaxation could be induced by oxygen loss during initial high voltage charging process and/or cation migration during cycling.
Cation substitution may be a way to retard VF of Li-rich layered cathode materials if the substituent can alter the path of structural degradation during the first charge in the parent phase. Our hypotheses for substitution study contain three criteria: (1) strong bonding with oxygen is required, (2) the oxidation state of the dopant can go higher than +4 and is stable (mitigate oxygen loss), and (3) it should form reversible dumbbell configuration with Litet during deep charge in order to maintain structural stability. Each substitution tried can fit into one of these classifications. This presentation will show the results from such substitutions and will describe the chemistry of these materials.
Synthesis and Understanding of Layered Li-Rich Nickel Manganese Oxides for High Voltage Lithium Ion Batteries
Authors: Boulineau Adrien , Simonin Loic , Colin Jean François , Peralta David , Feydi Pierre , Fabre Frederic , Chapuis-Rey Marlene , Daniel Lise , Martinet Sebastien , Patoux Sebastien 
Published: February 2020

In the search for high capacity cathode materials for Li-ion batteries, layered oxides with the general formula Li(LiXMnYMZ)O2 (M=Ni, Mn, Mg, ...) either described as xLi2MnO3 · yLiMO2 are receiving much attention. These oxides are characterised by the presence of lithium in the transition metal layers, and high Mn content, leading to high capacities up to 250mAh.g-1. However, upon cycling, they present complex structural changes that are still misunderstood.
In this context, our group worked jointly on synthesis development and understanding of the structure evolution occurring into the lithium rich layered cathode material Li1.2Mn0.61Ni0.18Mg0.01O2.
The first step was to study one material synthesized using a solid state route. 1st cycle characterization was investigated by XANES, in situ XRD and SQUID magnetic measurements. We showed that the main first-charge plateau is a twophase process where a new phase is created. This extra phase apparition was confirmed by Electron Energy Loss Spectroscopy (EELS) spectra interpretation. Therefore, Squid magnetic measurements allow a 1st cycle mechanism proposition.
Evolutions after cycling test (50 cycles) have also been investigated using advanced microscopy tools (High Resolution STEM EELS spectrum imaging). The stability of the spinel defect structure is pointed out to explain the material ageing and the electrochemical performances decrease on cycling.
Others synthesis routes were developed, especially solvothermal way enabling a better primary particles size, composition and morphology control. Higher performances and cycling behaviour have been obtained and further understanding studies are under progress to match with experimental observations.
Thin Film Silicon-Based Intermetallic Systems for Lithium Ion Battery Application
Authors: Schmuelling Guido , Renger Katrin , Reyes Jimenez Antonia , Meyer Hinrich Wilhelm , Winter Martin 
Published: February 2020

The demand for high energy lithium-ion battery systems has increased tremendously in the last few decades.[1] The most common anode material nowadays is graphitic carbon due to its long cycle life, low cost and abundant availability. Its drawback comes within a rather low specific capacity of 372 mAh/g. [2] To meet the requirements of next generation lithium ion batteries, new anode systems with a higher theoretical capacity are needed. A promising candidate to replace graphite is silicon, as it offers a capacity exceeding 3500 mAh/g at room temperature, while still being environmentally friendly and easily available. The main challenge before implementing Si as anode material is its enormous volume expansion upon lithiation causing the electrode material to collapse, thus resulting in a short cycle life. [3]
One approach to address this issue is the use of a stabilizing matrix, in which silicon is embedded. Therefore, several different alloy or intermetallic phase systems consisting of Cr, Ni, Ti or Mg in combination with Si are investigated on their use as a stabilizing matrix for Si based anode systems. Thin films of the binary systems are obtained via a co-magnetron sputter deposition process, in which we are able to steer the composition of the system by varying different parameters like the applied RF power during deposition. The as prepared thin films are electrochemically characterized by galvanostatic cycling as well as cyclic voltammetry. Embedding silicon in different alloys or intermetallic phases drastically changes the electrochemical performance, increasing capacity retention and cycle life of the anode system in lithium ion battery application.

References:

[1] J.B. Goodenough, Accounts Chem Res, (2012).
[2] M. Winter, Chem Unserer Zeit, 33 (1999) 320.
[3] U. Kasavajjula, C.S. Wang, A.J. Appleby, J Power Sources, 163 (2007) 1003-1039.
Mesoporous Carbon-Sulfur Composite Microspheres with Multiscale Morphology Control to Achieve High Areal Capacity for Lithium-Sulfur Battery Cathodes
Authors: Xu Terrence , Song Jiangxuan , Wang Donghai 
Published: February 2020

Lithium-sulfur (Li-S) batteries are widely regarded as the next-generation energy storage technology, due to their high potential in energy density and a low projected cost. Practical applications of such batteries are plagued with radical challenges that mainly stem from two factors. First, both sulfur and its final lithiation product, Li2S, are insulating. Thus, the reaction kinetics is slow and often leads to a low attainable capacity. Second, active material dissolve in the electrolyte in the form of lithium polysulfides. This dissolution causes a series of problems, including loss of cathode materials by diffusion away from the cathode, collapse of the cathode structure, and the polysulfide shuttle effect. As a result, Li-S batteries commonly show fast capacity decay and low coulombic efficiency.
Herein, we report the exceptional battery performance of porous carbon-sulfur composite microspheres, PSC-S, that benefited from simultaneous control of nanostructure and microscale particle morphology. The porous carbon microspheres (PSC) was synthesized as the sulfur host,by combining emulsion polymerization and evaporation-induced self-assembly (EISA) process, with a good control of both pore structure and microscale particle morphology. Such material not only demonstrated superioty in attainable capacity, but also in several other critical parameters for the development of high-energy Li-S batteries. PSC-S composite boasts a high tap density of 1.08 g/ml and contains 75 wt.% sulfur embedded into the mesopores of its carbon framework. At a high sulfur loading of 5 mg-S/cm2 and 60wt.% sulfur content in the electrode, this material delivers both high gravimetric and high volumetric capacity with excellent retention. Carbon nanotubes (CNTs) can also be readily incorporated into the microspherical structure in the synthesis process to form a porous spherical carbon-carbon nanotube-sulfur composite (PSC-CNT-S). CNT incorporation effectively raises the conductivity of the composite, and thus significantly improves its high-rate performance. At a high current density of 2.8 mA/cm2, an initial capacity of 1100 mAh/g and a reversible capacity of 700 mAh/g after 200 cycles were achieved in PSC-CNT-S. The resultant areal capacity of over 3.5 mAh/cm2 is much higher than in previous reports of Li-S cathodes fabricated using coating techniques.
Electrochemical Characteristics of PEO-Based Ternary Polymer Electrolyte for Lithium-Oxygen Batteries
Authors: Kim Yong-Han , Jadhav Harsharaj S. , Kalubarme Ramchandra S. , Park Chan-Jin 
Published: February 2020

The biggest advantage of metal-air batteries is their high theoretical energy density. Furthermore, they use oxygen from nature and exhibit eco-friendly characteristics. Lithium-air battery is recognized as a potential candidate for the application in EV. In particular, lithium-air battery shows a similar theoretical energy density (11,140 wh/kg) to that of gasoline (13,000 wh/kg). However, its performance has still been limited by problems such as the stability of lithium metal. In practical applications for electric vehicles, air containing moisture should be used. The exclusion of water from air is difficult using a conventional filter, hence lithium metal can react vigorously with the water from moisture and make the battery unsafe for use. Thus, the protection of Li-metal from water is the critical problem for rechargeable Li-air batteries. The other prominent problem for rechargeable lithium-air batteries is the lithium dendrite formation during repeated charge and discharge cycles; the dendritic Li-metal causes an internal short circuit. To overcome this problem, the key component of aqueous type lithium-air batteries is the water stable LISICON type lithium conducting solid electrolyte, since lithium metal reacts severely with water. However, the LISICON type solid electrolytes are not stable in contact with Li-metal. Thus, interlayers are needed between the solid electrolyte and Li-metal, which must be chemically stable in contact with Li-metal during operation and should have high lithium ion conductivity. PEO-based polymer electrolytes are best candidates as an interlayer. However, conductivity of PEO-based electrolytes is still much lower compared to that of liquid and inorganic solid electrolytes. The PEO-LiTFSI electrolyte has the ionic conductivity of the order 10-6 S×cm-1 at room temperature. In order to use PEO-LiTFSI as an interlayer, its ionic conductivity needs to be improved. In the present study, an ionic liquid has been added to PEO-based polymer electrolyte to increase its ionic conductivity.
The ionically conducting polymer membrane was prepared by casting technique. Microstructure and morphology of surface were obtained by FE-SEM and optical microscope. The samples were obtained by optimizing the ratio of PEO, Li salt and ionic liquid. The ac impedance of symmetric cells were measured in frequency range of 1 Hz ~ 1 MHz. The stability test indicates that the PEO based polymer electrolyte improves the stability between the Li-metal and solid electrolyte with improved conductivity. The ac impedance and charge discharge performance measurements for Li-O2 cell employing the polymer and LAGP solid electrolyte layers for the protected lithium electrode were also carried out. The Li-O2 cell with the developed polymer electrolyte exhibited a favorable discharge-charge performance.
Magnesiothermic Reduction of Structured Silica As Anode for Lithium Ion Batteries
Authors: Schrandt Matthew , Smirnova Alevtina , Cook Rob , Rhine Wendell , Kolla Praveen 
Published: February 2020

In lithium ion batteries, Si-based anodes possess the highest specific capacity from four to 10 times greater than graphite [1, 2]. However, up to 400% volume expansion of Si during lithiation results in anode pulverization due to mechanical stresses. To avoid mechanical degradation of silicon, the critical value of the silicon particle size/wall thickness should be below the required threshold of <50nm [3,4]. Thus, it is crucial to maintain the silicon particle size in this range. The second major requirement for silicon anode in lithium ion batteries is to have the second conductive phase, e.g. graphite or graphene, in the form of a flexible coating that can withstand lithiation-delithiation without deterioration of the carbon phase. The goal is to develop a silicon-based anode that can withstand lithiation-delithiation cycles without mechanical degradation.
Through using structured silica precursors, the goal is to reduce the silica to silicon while maintaining its structure and porosity and thus mitigate the degradation during cycling. Two types of silicon oxide precursor materials that meet these requirements have been evaluated, among them hollow silica microspheres from 3M and silica aerogel from Aspen Aerogels. The major steps including silica synthesis and magnesium vapor reduction will be discussed.
Preparation of Si precursor materials has been performed by magnesium reduction followed by the removal of unnecessary impurities such as magnesium oxide and silica by washing the material in 1M HCl followed by 1% HF. Preliminary data from XRD confirms Si formation from the magnesiothermic reduction. SEM, TEM, EDS, BET, XRD, and Raman spectroscopy will be presented to analyze the structure and morphology of the materials. Structure dependent electrochemical properties such as cyclic voltammetry, cycleability, galvanostatic discharge, and cycle stability will be discussed.
Fig. 1: (A) TGA for 3M silica microspheres (iM30K) and (B) TGA for Aspen Aerogels’ SiO2 aerogel with Mg with the corresponding SEM images (C) 3M microspheres and (D) Silica aerogel precursors. (E) XRD for reduced SiO2 aerogel: top profile is fully washed reduced Si, middle profile is after reduction but before washing, and bottom profile is for a Si nanopowder reference to vindicate successful Si reduction from SiO2.
References:
[1] A. Kraytsberg, Y. Ein-Eli, J. of Power Sources, 196 (2011) 886.
[2] W. J. Zhang, J. of Power Sources, 196 (2011) 13.
[3] X. H. Liu, L. Zhong , S. Huang, S. X. Mao, T. Zhu, J. Y. Huang, ACS Nano, 6 (2012) 1522.
[4] U. Kasavajjula, C. S. Wang, A. J. Appleby, J. of Power Sources, 163 (2007) 1003.
Nb2O5 anchored-Graphene Hybrid Nanocomposites As High Performance Anode for Lithium Ion Batteries
Authors: Arunkumar P , Ashish A. G , Sarang Som , Abhin S , Shaijumon Manikoth M 
Published: February 2020

With the ever-increasing demand for energy storage, lithium ion battery has been an attractive technology, which has revolutionized the portable electronic industry and has recently become popular in the electric vehicle market, due to their superior energy density [1]. Innovative materials chemistry has been the key to various advancements in lithium rechargeable battery [2]. Various transition metal oxides have been widely studied as electrode materials for rechargeable lithium-ion batteries because of their high theoretical capacity, safety, environmental benignity and low cost [3]. Recently, there is great interest in developing graphene-based nanocomposites as high performance electrodes, owing to the multifunctional attributes of such electrodes [4]. Such materials designs are expected to offer marked improvements in energy and power densities.
Here, we present the synthesis of Nb2O5 anchored graphene hybrid nanocomposites through simple hydrothermal method and their application as high performance anodes for lithium ion battery. Self-supported nanostructured electrode with graphene as support and with homogenously anchored Nb2O5 nanoparticles has been obtained as shown in Figure 1a. Nanostructured hybrid electrodes have been characterized by X-ray diffraction (XRD), Scanning and Transmission Electron Microscopy (SEM/TEM). Cyclic voltammetry and Galvanostatic charge-discharge cycling measurements have been performed using hybrid nanocomposites as positive electrodes in 1 M LiPF6 –EC/DMC electrolyte vs.Li metal negative electrodes. Electrochemical studies of these hybrid electrodes show improved reversible capacities and power capabilities.
Conducting graphene sheets improves the kinetics of the lithium ion and electron transport, and conductivity of the metal oxide by the enhanced particle-particle contact and buffering action during lithiation. Synergistic effect of both Nb2O5 nanocrystals anchored onto conducting graphene layers showed reversible capacity of 192 mAhg-1 up to 50 cycles with C/10 rate, indicating two electron transfer process in LixNb2O5
(Figure 1b). Nb2O5anchored graphene sheets with superior electrochemical performance of high reversible capacity, enhanced rate capability, including an improved electronic and ionic conductivity, can be ideal anodes for high performance lithium ion battery.

Figure1: (a) TEM image of Nb2O5-anchored graphene nanocomposites; (b) Charge-discharge galvanostatic curves for Nb2O5-anchored graphene electrtodes cycled at a rate of C/10 versus Li and using a charge cut off voltage of 1 V.

References

J. -M. Tarascon, M. Armand, Nature, 414 (2001), 359.

P. G. Bruce, B. Scrosati, J. -M. Tarascon, Angewandte Chemie International Edition, 47, (2008), 2930.

P. Poizot, S. Laruelle, S. Grugeon, L. Dupont & J-M. Tarascon, Nature 407, (2000), 496.

Z.-S. Wu, W. Ren, L. Xu, F. Li, H.-M. Cheng, ACS Nano 5, (2011), 5463.