bluuebunny/crossref_metadata_2025_split huggingface dataset:
High Tap Density MgO Doping Composite Composition 0.5Li2MnO3-0.5LiNi0.5Mn0.5O2 Cathode Material
Authors: Kumar Arun , Tomar Maharaj 
Published: February 2020

Introduction
Last decade Lithium-rich layered and spinal base oxide materials have been studied as a promising cathode material for using in the next generation high energy lithium-ion batteries for intensively pursued for electric and hybrid electric vehicle applications. Commercial lithium ion cells are currently made largely with the layered LiCoO2 cathode. However, only 50% of the theoretical capacity of LiCoO 2 can be utilized in practical cells due to the chemical and structural instabilities at deep charge as well as safety concerns. One of these layer materials composite , xLi2MnO3-(1-x)LiNi0.5Mn0.5O2 (0<x<1) has been widely studied since Thackeray et al. discovered it when they were researching the LiMnO2 layered material.1 This material shows capacities larger than 280 mAhg-1 and operating voltages larger than 4.5 V making it one of the cheapest high energy density material for Li-ion batteries. However, many challenges must be overcome in order to realize its commerciality, for example its poor capability and its voltage degradation during cycling.2

In this study, we are doping MgO with composite cathode. The effect of doping not only will provide stability in the composite structure in the lithiation and delithiation process, also improve electrochemical properties..
Experimental
0.5Li2MnO3-0.5LiNi0.5Mn0.5O2 has been synthesized using carbonate based co-precipitation method.
The structural and morphological features have been studied by powder X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Figure 1 shows the XRD patterns of as-synthesized LNMO powder. Results show the complete two phases formation of composite material corresponding to the two group space of R3m (LiNi0.5Mn0.5O2) and C2/m (Li2MnO3). This patterns were compare with JCPDS database, #84-1634 for Li2MnO3 and #09-0063 for LiNi0.5Mn0.5O2, which have been well indexed on the basis of LiNiO2 structure.1

SEM measurements show highly dense particle agglomerations, particle size lies to 0.5-2 μm, while agglomerations around 10-20 μm. Smaller particles are strongly related with a good electrochemical behavior.
Electrochemical properties will be study using cyclic Voltammetry, Charge-Discharge Curves, and Electrochemical Impedance spectroscopy (EIS). These measurements are still in progress.
Figure 1. XRD patterns of as prepared LNMO powder. Inset shows the small picks between 20-30 degrees related to the monoclinic Li2MnO3 structure,
References

[1] Haijin Yu et al., J.
Phys. Chem. Lett.,
4, 1269 (2013)
[2] Gurpreet Singh et al., J. Electrochem. Soc.,
159 (4), A3 (2012)
The Promise of Aqueous Chemistry Semi-Solid Flow Cells (SSFCs)
Authors: Davies Greg , Steingart Daniel A. 
Published: February 2020

For large scale energy storage and long distance transport applications it is necessary to decouple the power output and capacity of the energy storage device to reduce costs to viable levels. Traditional flow batteries offer this power/capacity decoupling, however, amongst other challenges, the typical energy densities are significantly lower than those available from standard closed cell battery designs.
More recently there has been interest in a new type of flow battery, the semi-solid flow cell (SSFC). This type of cell combines the advantages of both flowing and solid battery concepts: the ability to decouple power output and capacity while still maintaining good energy densities. Suggested SSFC electrochemistries to this point have been mostly based on Li-ion technology. We will present research based on an aqueous SSFC chemistry, which has the potential to be safer and cheaper than Li-ion technologies. The important features of the system, and the promise of this technology for future large scale energy storage or transport applications will be considered.
Coking Study in Anode Materials for SOFCs: Physicochemical Properties and Behavior of Mo-Containing Perovskites in CO and CH4 Fuels
Authors: Zheng Kun , Świerczek Konrad , Carcases Nahum Maso , Norby T. 
Published: February 2020

Recent research trend on Solid Oxide Fuel Cells is aimed at utilizing non-hydrogen fuels [1-4]. When SOFC is running on syngas, methane and/or other hydrocarbons, on the typical Ni-YSZ anode carbon deposition occurs, which consequently significantly decreases SOFC cell performance, due to a decrease of the triple phase boundary catalytic sites, which are blocked by coking [1, 2]. Among candidate anode material for usage with such fuels, A2MMoO6-δ(A: Sr, Ba; M: 3d metals) ordered perovskites seem to be particularly interesting [3, 4]. However, the coking mechanism in such compounds is still under intensive research, due to a fact that carbon deposition process is affected with many factors, such as operation temperature, water content, etc. [1, 2].
In this study, B-site modified double perovskites with Sr2Fe1.5-xMnxMo0.5O6 formula were investigated as candidate anode materials for SOFCs operating with syngas and/or methane, in terms of their crystal structure, oxygen nonstoichiometry, chemical stability, their electrochemical properties, and carbon deposition tolerance in CO and/or CH4 gases. The coking effect on the electrical conductivity and SOFC performance was studied at different temperatures. Deposited carbon morphology, as well as degradation of microstructure of the materials were investigated by SEM. It was found that carbon deposition is significantly dependent on the operation temperature and annealing time. Elucidation of the coking mechanism on Sr2Fe1.5-xMnxMo0.5O6-based anodes is given.

Acknowledgments

The project was funded by the National Science Centre Poland (NCN) on the basis of the decision number DEC-2011/03/N/ST5/04785.
One of the authors (K. Zheng) acknowledges financial support from the National Science Centre Poland (NCN) under the ETIUDA doctoral scholarship on the basis of the decision number DEC-2013/08/T/ST5/00100.

References

1. X. Ge, S. Chan, Q. Liu, Q. Sun, Adv. Energy Mater. 2 (2012) 1156-1181.
2. T. Chen, W. Wang, H. Miao, T. Li, C. Xu, J. Power Sources 196 (2011) 2461-2468.
3. Y.H. Huang, R.I. Dass, Z.L. Xing, J.B. Goodenough, Science 312 (2006) 254-257.
4. K. Zheng, K. Świerczek, W. Zając, A. Klimkowicz, Solid State Ionics 257 (2014) 9-16.
Study on the Oxygen Bonding Energy to Pt by Valence Band DOS Measurement of Pt Nano-Particle Catalysts
Authors: Hidai Shoichi , Ishii Kenji , Matsumura Daiju , Niwa Hideharu , Miyawaki Jun , Aoki Tsutomu , Oshima Masaharu , Harada Yoshihisa 
Published: February 2020

In order to improve the catalytic activity and durability of PEFC cathode Pt catalysts the particle size and ligand effects on the oxygen bonding energy of a Pt nano-particle catalyst were evaluated from the valence band DOS of Pt by using resonant inelastic X-ray scattering (RIXS). The RIXS measurement is suitable to probe changes of the valence band states by oxygen adsorption because it is element specific and compatible with ambient pressure. A hard X-ray whose photon energy is slightly lower than the Pt L
3 absorption edge was introduced on the sample to eliminate fluorescence component and subsequent emission by transition from the Pt valence states to the 2p core hole was detected as a function of energy transfer as shown in Fig. 1.
The RIXS spectra of Pt nano-particle catalysts measured by 11.563 keV excitation are shown in Fig. 2. The mean particle diameters are evaluated from TEM images to be from 1.6 to 3.9 nm. The main peaks in the region between 2 and 4 eV can be assigned as X-ray Raman peak which comes from the bonding between platinum and oxygen. The X-ray Raman peak position decreases with increasing mean particle diameter as shown in Fig. 2.
The energy transfer value of X-ray Raman peak position can be closely related to the oxygen bonding energy with Pt. Therefore Figure 2 suggests that the oxygen bonding energy to Pt decreases with the Pt particle size. Strong bonding between oxygen and Pt might reduce the catalytic activity and the durability of Pt nano-particles with diameters less than 3 nm. Alloying with transition metals also changes the bonding energy of oxygen to Pt. Based on these results, relationship between electronic structure and catalytic activity will be discussed.

Acknowledgement

This work was supported by New Energy and Industrial Technology Development Organization (NEDO). The RIXS experiments were approved by the Japan Atomic Energy Agency (JAEA) Proposal Review Committee (Proposal No. 2010B3575, 2011A3574 and 2013A3514).
PVA/Polyelectrolyte Bipolar Membranes for Fuel Cell Applications
Authors: Staser John A , Movil-Cabrera Omar , Frank Logan 
Published: February 2020

In the last few years, direct borohydride/hydrogen peroxide fuel cells (DB/HPFC) have attracted considerable attention due to their potential use as air-independent power sources in undersea vehicles. In general, a DB/HPFC system can be built using either a cation exchange membrane (CEM) or an anion exchange membrane (AEM) as a polymer electrolyte. Unfortunately, to date, these systems exhibited low efficiency, mainly due to some problems related to the intrinsic properties of the polymer electrolyte themselves. Bipolar membranes are promising candidates to improve the efficiency of DB/HPFC systems, since these incorporate advantageous features of both AEM and CEM, and also mitigate the loss of fuel.
The present work focuses on the fabrication and characterization of a novel bipolar membrane for DB/HPFC applications. The first goal is to fabricate water-soluble PVA-based AEM and CEM with both high ionic conductivity and excellent mechanical stability. For this purpose, a variety of AEMs are prepared via polymer blending of PVA and poly(diallyldimethylammonium chloride) (PDDA) or poly(acrylamide-co-diallyldimethylammonium chloride) (PACoDDA). Similarly, CEMs are fabricated via polymer blending of PVA and acid polymer ((poly (styrene sulfonic acid) (PSSA) or poly (acrylic acid) (PAA)). Subsequently, the membranes are cross-linked using a chemical or physical method. The chemical cross-linking is performed at different concentrations of glutaraldehyde (GA), whereas the physical cross-linking is performed at different temperatures. The electrical, mechanical and morphological properties of these membranes are evaluated as a function of PVA content and cross-linking process conditions. Some of the material characterization techniques used in this study include, but are not limited to: Fourier transform infrared spectroscopy (FTIR), four-electrode impendence measurement, transmission electron microscopy (TEM), and tensile tests. Preliminary results indicate that PVA-PDDA and PVA-PSS membranes have excellent mechanical and alkaline stability. Also, the maximum OH− conductivity of 8.57E-3 S cm−1 was achieved for physically cross-linked PVA/PDDA membrane with a polymer composition of 70/30 as shown in Figure 1a. In the case of CEM, the high H+ conductivity of 1.77E-2 S cm−1 corresponds to the chemically cross-linked PVA-PSS membrane with a polymer composition of 70:30 (see Fig. 1b).

Figure 1. Ionic conductivity as a function of PVA content for (a) PVA/PDDA membranes and (b) PVA/PSS membranes.
MEA Pt/C Cathode Catalyst Degradation during Repeated Anode Gas Exchange Cycles: In-Situ XAFS, STEM-EDS and Electrochemical Analysis
Authors: Samjeské Gabor , Higashi Kotaro , Takao Shinobu , Nagamatsu Kenichi , Nagasawa Kensaku , Sekizawa Oki , Kaneko Takuma , Uruga Tomoya , Iwasawa Yasuhiro 
Published: February 2020

The start-up and shut-down processes in polymer electrolyte fuel cell (PEFC) operations involve anode gas (fuel) mixing with air, which may diffuse into the Pt/C anode from either the anode gas outlet or the Pt/C cathode through the Nafion membrane. This causes a transient, short-lived anode-condition, in which a part of the anode catalyst layer is exposed to hydrogen while another is exposed to oxygen (air). The resulting mixed gas-condition leads to oxygen reduction reaction (ORR) at the oxygen-covered area of the anode, while hydrogen oxidation reaction takes place at the hydrogen-covered area of the anode, by the so called reverse current decay mechanism./1/

The electrolyte potential (potential of the Nafion layer) is drawn to negative values in the air-covered regions to facilitate the ORR on the anode, thus causing the potential difference between the Nafion layer and cathode catalyst layer on the corresponding areas of the cathode to increase up to 1.6 V. At the high potentials not only dissolution of Pt from the cathode catalyst but also oxidative corrosion of the carbon support take place.
We have measured the Pt/C cathode catalyst in PEFC during repeated fast anode-gas exchanges (AGEX) cycles by means of in-situ time-resolved XAFS, to study the structural and electronic transformations of Pt nanoparticles at the cathode caused by the AGEX cycles. The in situ XAFS and time-resolved XAFS techniques together with STEM-EDS provided new insights into the origin and mechanism for the Pt/C cathode catalyst degradation by the AGEX cycles.

/1/
Carl A. Reiser et al.; Electrochem. Solid-State Lett.; 2005 (6) A273
Cathode Design of Non PGM Catalysts for Anion Exchange Membrane Fuel Cells
Authors: Asazawa Koichiro , Nishino Eriko , Kishi Hirofumi , Miyake Junpei , Uchida Makoto , Miyatake Kenji , Watanabe Masahiro 
Published: February 2020

An anion exchange membrane fuel cell (AEMFC) using hydrazine hydrate liquid fuel has been developed1 and the concept vehicle powered by Precious Metal free Liquid Feed Fuel Cell (PMfLFC) was exhibited at the 42nd and 43rd Tokyo Motor Show. For the improvement of the AEMFCs, technological breakthrough is necessary for anion exchange membranes. Especially, it is important to overcome the counteracting relationship of high ion conductance and low fuel permeability. And also, technology to control triple-phase interface formed by catalyst and ionomer is important to improve the performance. Our approach to develop the advanced AEMFC is using anion conductive quaternized aromatic multiblock copolymers, poly(arylene ether)s (QPEs)2 and control the interface and non platinum group metal (PGM) catalysts both for anode and cathode. Even for state-of-the-art proton exchange membrane fuel cell electrode that consists of Pt catalysts and perfluorinated ionomer, triple-phase interface has not been optimized and the catalyst utilization is still insufficient. This is also the case for non PGM catalyst and anion exchange ionomer. In this paper, for the preliminary study we focus on electrode design for cathode and evaluated pore size of non PGM catalyst and distribution of catalyst in the ionomer solution. The non PGM catalysts formed meso pores (10-100nm) with the mixture of carbon materials. There are two different types of pores, one is inside of the catalyst itself and the other one is outside pores between the catalysts. Mixture of non PGM catalyst and carbon materials are increased meso pores. Oxygen reduction reaction (ORR) activity of the non-PGM catalysts was evaluated in 1M KOH aq using rotating ring disk electrode (RRDE). The Fe-N-C non-PGM catalyst showed comparable ORR performance to platinum/carbon catalyst (TEV10V60E). The half wave potentials were 0.886V and 0.849V, respectively. MEA consists of the QPE membranes and ionomers were fabricated with non-PGM catalysts and subjected to performance evaluation. The MEA performance of direct hydrazine fuel cells will be shown and discussed in the meeting.
References
[1] K. Asazawa, H. Tanaka, U. Martinez, B. Halevi, A. Serov, K. Artyushkova, P. Atanassov, and B. Kiefer, Abstract #1610, Honolulu PRiME 2012
[2] M. Tanaka, K. Fukasawa, E. Nishino, S. Yamaguchi, K. Yamada, H. Tanaka, B. Bae, K. Miyatake, and M. Watanabe, J. Am. Chem. Soc. 2011, 133, 10646–10654
The Effect of Cathode Pressure Perturbations on the Voltage Stability of a Simulated Fuel Cell Stack
Authors: Burkholder Michael , Litster Shawn 
Published: February 2020

During polymer electrolyte fuel cell (PEFC) operation, proper water management is necessary to optimize performance [1]. It is desirable to have enough water to fully hydrate the electrolyte membrane with no excess liquid water to interfere with the transport of oxygen to the cathode, causing power loss. However, the air flow rate and pressure drop used to remove liquid water from the cathode and maintain power can cause large parasitic power losses. Low cathode pressure drops that are parasitically inexpensive to maintain lead to voltage instability and loss [2], while high flow rates and pressure drops stabilize voltage at the cost of a higher parasitic load on the PEFC and lower system efficiency.
In this work, we perform experiments on a simulated fuel cell stack that consists of a constant hydraulic resistance bypass around the cathode, allowing air flow to the cathode to divert through the parallel bypass as the cathode's hydraulic resistance changes in the presence of liquid water. This bypass can be used to simulate a stack of unflooded cells in parallel with the experimental cell [2]. Downstream of the simulated stack we placed a solenoid valve followed by a pressure regulator to apply controlled pressure perturbations to the simulated stack. The perturbations consist of a short (< 1 second) reduction in backpressure followed by backpressure recovery. The PEFC cathode was also equipped with a differential pressure transducer to measure the pressure drop across the flow field. We formulated reduced order nonlinear statistics based on chaotic invariants (the Lyapunov exponent of the voltage return map, λ) to quantify the level of instability in the PEFC and implemented a computer program to monitor the PEFC stability in real time.
Using the simulated stack under galvanotstatic operation, we recorded the PEFC voltage, cathode differential pressure (ΔPc), and λ responses to varying magnitudes of pressure perturbations during operation in an unstable regime (low current density, low air flow rate). We found that the pressure perturbations stabilized the voltage, Fig. 1, while allowing for a reduced pressure drop. We then implemented a control scheme that monitors the Lyapunov exponent for values above a threshold and applies a corrective pressure perturbation when this occurs. As Fig. 2 shows, this control scheme recovered lost power, stabilized voltage, and reduced cathode pressure drop with minimal energetic expense.
References
[1] N. Yousfi-Steiner et al., Journal of Power Sources 183 (1) (2008) 260-274.
[2] J.P. Owejan et al., Journal of Power Sources 171 (2) (2007) 626-633.
Investigation of Performance and Durability of MEAs at Higher Temperature
Authors: Kitamura Masahiko , Minamida Yasuto , Zhao Xiaojing , Noda Zhiyun , Hayashi Akari , Sasaki Kazunari 
Published: February 2020

Polymer electrolyte fuel cells (PEFCs) recently attract more attention because fuel cell vehicles (FCVs) are commercially available from 2015. Even though the technology for the first generation FCVs has been mainly established, for the next generation FCVs, the operation at high temperature is desired in order to improve the power generation efficiency and durability. The target operating temperature is about 120 °C for FCVs. Since there are still technological problems for electrolyte membranes over 100 °C, almost no report is found about either performance or durability under such a condition at present. Here, the objective of our study is to extract the problems on the catalytic degradation at higher temperature. In this study, we have evaluated performance and durability of MEAs under higher temperature like 105 °C and low humidity such as RH57%.
MEAs were manufactured using a standard Pt/Ketjen black catalyst (TEC10E50E, TKK Corp.) and Nafion. Then, their IV characteristics were examined. Regarding to the durability evaluation, two protocols[1] recommended by Fuel Cell Commercialization of Japan (FCCJ), “load cycles” and “start-stop cycles”, were in use. Three different conditions of operation temperature and humidity (80 °C/RH100%, 105 °C/RH57%, and 80 °C/RH57%) were applied. Then, the effects of such conditions on both performance and durability of MEAs were evaluated.
On evaluation of IV performance in three different conditions before and after the load cycle durability tests, the operation at 105 °C greatly deteriorated the performance than at 80 °C. Also, by comparing two different humidity conditions at 80 °C, the lower humidity led to the smaller degradation. Moreover, the change in electrochemical surface area (ECSA) was examined at the same time, and then the retention of ECSA was lower under both higher temperature and higher humidity, likewise. In addition, SEM observations were performed to see the change in Pt particle size. As a result, Pt grain growth was confirmed after the load cycle durability tests. The average particle size became larger at both higher temperature and higher humidity. In other words, a similar trend to the deterioration of IV performance was obtained. Here, we believe that one possible reason why the deterioration was suppressed at lower humidity comes from the existence of less water relating to the diffusion of Pt ions. Similarly, the examination on the start-stop cycle durability tests will also be reported.
Reference
[1] A. Ohma et al., ECS Trans, 41 (2011) 755.
Tolerance of Impurities in Bio-Ethanol on Pd/C Catalyst Toward the Ethanol Oxidation Reaction in Alkaline Media
Authors: Chen Rongrong , Qi Jing 
Published: February 2020

In the recent years, bio-ethanol could be produced massively from various sources and has attracted great interests as an alternative fuel source in low temperature fuel cells. However, the bio-ethanol may contain some impurities, such as lactic acid, acetic acid, glucose, glycerol, maltose, fructose and so on, to contaminate the catalysts in the fuel cells. The objective of this work is to investigate the effects of impurities in bio-ethanol on the performance of Pd/C catalyst for the ethanol electro-oxidation reaction (EOR) in alkaline media.
The electrocatalytic activities of Pd/C toward EOR with the addition of 0.01 M of various organic compounds were tested by cyclic voltammetry (CV). By comparing the EOR current at the corresponding potential, the presence of lactic acid and acetic acid was found to have little effects on the electrocatalytic activity of Pd/C toward EOR; however, the performance of Pd/C toward EOR get worse with the presence of glucose, glycerol, maltose, and fructose.
The quasi-steady state current for EOR on the Pd/C catalyst was also measured by chronoamperometry (CA) measurements. The EOR current of the Pd/C decayed slowly with time. The steady currents at 0.5 V for EOR on Pd/C catalyst exhibit the order of EOR » EOR+0.01 M lactic acid > EOR+0.01 M acetic acid > EOR+0.01 M glucose > EOR+0.01 M glycerol > EOR+0.01 M maltose » EOR+0.01 M fructose. This trend is consistent with the CV test results.
The tolerance of impurities in bio-ethanol on other catalysts toward the ethanol oxidation reaction in alkaline media will be also studied and discussed.