bluuebunny/crossref_metadata_2025 huggingface dataset:
3D Printing of Functional Layers for Solid Oxide Fuel Cells and Electrolysers
Authors: Farandos Nick , Kleiminger Lisa , Hankin Anna , Ong Chin Kin , Kelsall Geoff H.
Published: February 2020

Energy conversion efficiencies of solid oxide fuel cells (SOFCs) and electrolysers (SOEs) can be increased, principally by increasing the density of triple phase boundaries (electrode | electrolyte | reactant gas in pores) where reactions occur. SOFCs and SOEs with infiltrated-scaffold composite electrode structures have been shown to have greater densities of triple phase boundaries (TPBs), and enhanced control of particle size and porosity compared with structures derived from powder mixing [
1
]. However, methods that fabricate reproducible and explicitly tailored scaffolds with micrometre length scales have yet to be reported. Hence, we are developing 3D inkjet printing, using a Ceradrop X-Series inkjet printer with three multi-nozzle print heads, to fabricate reproducible, structured ceramic frameworks with ca. 5 µm resolution, prior to sintering. Ultimately, this should enable fabrication of percolated (porous) cathode | (non-porous) electrolyte | (porous) anode structures much more reproducibly and with greater definition than hitherto, to achieve increased energy conversion performances. The reproducible geometries will also enable more facile comparison of experimental performance and model predictions [2].

One prerequisite is the development of stable dispersions (‘inks’) of sub-micrometre sized metal oxide particles (i.e. (ZrO2)0.92(Y2O3)0.08, NiO, La1-xSrxMnO3-δ) in liquid phases with suitable solids fractions and physical properties, for which results will be presented (Fig.1a). These inks have been used to print the functional layers of SOFCs/SOEs (Fig.1b). However, geometries of electrode | electrolyte structures are subject to limitations imposed by the requirement to minimise the spatial distributions of potential and current densities. Hence, results will also be presented for predictions (Fig.2) of those parameters, modelled using finite element software, and preliminary current density-potential difference data for a printed SOE.

Firstly, yttria-stabilized zirconia (YSZ) particles were deposited onto a planar YSZ | NiO substrate, as pre-cursors to a thin (ca. 10 µm), gas-tight electrolyte, formed by heating the green structure to ca. 500°C to burn out organics used to stabilise ink particles against aggregation, followed by sintering YSZ at ca. 1400°C. Subsequently, YSZ and NiO nanoparticles were co-printed with an organic polymer to fabricate porous electrode structures on non-porous YSZ electrolyte layers.

Reference

M. Kishimoto, M. Lomberg, E. Ruiz-Trejo, N.P. Brandon, Enhanced triple-phase boundary density in infiltrated electrodes for solid oxide fuel cells demonstrated by high-resolution tomography, J. Power Sources, 266 (2014) 291-5.

U. Doraswami, P. Shearing, N. Droushiotis, K. Li, N.P. Brandon and G.H. Kelsall, Modelling the Effects of Measured Anode Triple-Phase Boundary Densities on the Performance of Hollow Fiber SOFCs, Solid State Ionics, 192 (2011) 494–500.

Figure 1
Investigation of Time Stability of Sr-Doped Lanthanum Vanadium Oxide Anode and Sr-Doped Lanthanum Cobalt Oxide Cathode Based on SDC Electrolyte Using SIMS
Authors: Tamm Kadi , Möller Priit , Nurk Gunnar , Lust Enn
Published: February 2020

Ceramic materials with the perovskite structure are considered as promising alternatives to Ni-based SOFC anodes. In this study La0.7Sr0.3VO3–δ-Ce0.85Sm0.15O2–δ (SDC) anode and La0.8Sr0.2CoO3–δ-SDC cathode were fabricated by infiltration the porous SDC scaffold with an aqueous solution of corresponding nitrates. The time stability of the SOFC single cell has been studied at temperatures 600 and 700°C. As a fuel the mixture of humidified hydrogen (partial pressure 0.2) and argon (partial pressure 0.8) has been used. During 220 h of operating (at 0.6 V) the decrease in maximum power density values at both temperatures was approximately 1%. The microstructure of the single cells, mostly the mobility of Sr within the cell, before and after the time stability measurements have been analyzed using secondary ion mass spectrometry. No degradation was observed during the cell preparation process and only minor elemental mobility was seen after 24 h of operation time. However, noticeable Sr mobility was seen after 220 h operating at 700°C.
Electrochemical Model of a Triode Solid Oxide Fuel Cell
Authors: Caliandro Priscilla , Diethelm Stefan , Nakajo Arata , Van herle Jan
Published: February 2020

A Triode Solid Oxide Fuel Cell is a novel cell architecture that aims to control the electrocatalytic activity under low steam reforming conditions, or poisoning conditions. This fuel cell design introduces a third electrode (auxiliary electrode) of the same nature of the cathode while the anode is common between the two circuits (Figure 1). The auxiliary circuit, which electrically connects the anode with the auxiliary electrode, is operated in electrolysis mode while the fuel cell circuit runs in its conventional way. During the triode operation, performance enhancement is recorded especially when a significant electrode overpotential is presented; this can be the case for SOFC anode feeds with natural gas and gasoline fuels, or when it is being poisoned from impurities. A two-dimensional stationary isothermal model is developed and implemented in commercial software, COMSOL Multiphysics (version 4.3b). The model is based on composite electrodes, where the equations for mass, momentum and charge transport, along with electrochemical global kinetics (Butler-Volmer equation) and charge conservation are solved simultaneously. Exchange current densities are fitted from experimental data to reproduce the observed behavior of the cell. The model, able to predict conventional and triode operation, gives guidelines for the electrodes geometry design that needs to be adopted in order to favor the expected improvements. In particular, it is noted that the aspect ratio between the electrodes distance cathode-auxiliary and the electrolyte thickness is a key parameter. The interaction between the main and auxiliary circuits is then discussed in terms of equipotential and current lines in a cross section of the cell for two different geometries: anode and electrolyte supported cells. The improvements achievable in triode operation are also calculated in terms of electric current surplus that is possible to obtain in the fuel cell circuit while imposing an electrolysis voltage of 1.7 V in the auxiliary circuit.

Figure 1
Development of Electrochemical Methanation Reactor with Co-Electrolysis of Humidified CO2
Authors: Yamaguchi Toshiaki , Shimada Hiroyuki , Honda U , Kishimoto Haruo , Ishiyama Tomohiro , Fujishiro Yoshinobu
Published: February 2020

Solid oxide fuel cells (SOFCs) have received a great deal of attention recently, due to in part to their high energy conversion efficiency and environmental compatibility. Recently, an electrochemical cell with the same components as SOFCs has also been used as a solid oxide electrolysis cell (SOEC) for Power-to-Gas process. The use of alternative high performance electrolytes and electrodes materials means that the input power for electrolysis can be reduced. Co-electrolysis of CO2 and H2O with SOEC is considered to be one of the effective technologies to convert CO2 and H2O into CO and H2 gases [1]. Typical operation temperature of SOEC above 600ºC prevents further methanation reaction of CO and H2, while CO and H2 gases (syngas) are useful raw material for CH4 at lower reaction temperatures around 400ºC. Very recently, various researchers reported the excellent electrochemical performances and durability of heat-cycles for SOEC designs. Most of the cells are supported by a porous fuel-electrode tube. Therefore the tubular fuel-electrode support works as a current collector and gas diffusion layer as well as support medium of SOEC. Thus, the aim of this study is to realize the electrochemical reactor development with a reliable electrolyte layer on the excellent gas permeation, conductivity and mechanical strength for direct methanation process using co-electrolysis of CO2 and H2O at lower cell operation temperatures. In this presentation, we will report SOEC reactor fabrication technologies and the methanation properties.

This research is partially supported by CREST program of the Japan Science and Technology Agency (JST).

Ref 1. Energy and Environmental Science, 7 (2014) 4018-4022
Framework for Analysis of Irreversible Fuel Cell Heat Engine Hybrids
Authors: Williams Mark C. , Gemmen Randall , Gerdes Kirk
Published: February 2020

A thermodynamic and electrochemical framework for the analysis of the degrading fuel cell heat engine hybrid is developed and explored for various working reactions.  Fuel cell hybrids are a combination of energy conversion sub-systems – fuel cells and heat engines.  Fuel cell hybrids are important for the future for they are the most efficient devices when converting chemical energy of methane from natural gas and renewable fuels to electricity. While the perfect fuel cell would undergo no degradation, practical fuel cells with irreversibilities will degrade.   The common practice is to linearize degradation. However, experimental evidence shows that ASR(t) is commonly an ohmic parabolic function.   By the principle of superposition one can easily develop the equations for degrading hybrids from those developed for hybrids.  The path of maximum power can be developed for degrading hybrids as a function of ASR and temperature. The maximum power for a degrading fuel cell hybrid is given by the Gaussian hypergeometric function. The range of the operation of the SOFC is likely most conducive to hybrid operation for hydrogen oxidation as the working reaction. Each working reaction has a characteristic transition temperature and a characteristic optimal operating temperature.
Enhancing Performance of Stabilized Bismuth Oxide-Based Cathodes via Infiltration Process for LT-SOFCs
Authors: Park Jin Wan , Yun Byeong Hyeon , Joh Dong Woo , Lee Kang Taek
Published: February 2020

Solid oxide fuel cells (SOFCs) are the most efficient technology to directly convert chemical energy to electrical energy via electrochemical reactions. However, commercialization of SOFCs has been impeded due to the high cost associated with high temperature operation over 800 oC with conventional stabilized zirconia electrolytes. Thus, lowering the temperature of solid oxide fuel cells (SOFCs) is essential for the commercialization via availability to use cheap stainless steel interconnector, rapid start-up time, and higher mechanical and chemical stability, leading to significant reduction of system cost. To achieve this goal, at reduced temperatures the cathodic polarization mainly caused by oxygen reduction reaction at triple phase boundaries (TPBs) should be effectively reduced.

  At lower temperatures below 700 oC, however, the cathode polarization exponentially increases due to its thermally activated nature, thus dramatically decreasing the performance. Previously, stabilized bismuth oxide-based composite cathodes (ex: LSM-ESB) have been reported as promising cathodes for LT-SOFC applications with their low area specific resistance (ASR) at LT region. This high performance would be explained that LSM has low activation energy for dissociative adsorption of oxygen in ORR on its surface and that ESB has exceptionally high ionic conductivity as well as excellent surface exchange properties. Therefore, one can expect that the microstructural optimization of these cathode could further increase the cathode performance as well as enhance the their durability.

In this study, we employed the infiltration process to tailor the surface morphologies of stabilized bismuth oxide-based composite cathodes for enhancing surface activity and their stability to achieve higher SOFC performance. Through infiltration, for example, LSM was infiltrated on the porous ESB scaffold with different manners. The microstructural evolution and electrochemical performance was characterized and their cross-effect will be discussed.
Enhanced Chromium Tolerance of La0.6Sr0.4Co0.2Fe0.8O3-δ Cathode by BaO Infiltration
Authors: Chen Kongfa , Ai Na , Jiang San Ping
Published: February 2020

Chromium deposition and poisoning of cathodes is one of the most important degradation mechanisms of solid oxide fuel cell (SOFC). In this presentation, we will report the development of a BaO modified La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode with substantial chromium tolerance, using EIS, SEM-EDS, XRD, XPS and ToF-SIMS. The BaO infiltration dramatically enhances the performance stability of LSCF in the presence of Fe-Cr interconnect. The infiltrated BaO nanoparticles inhibit the formation of SrCrO4 by forming thermodynamically stable and conducive BaCrO4, preventing the extraction of Sr at the A-site of LSCF perovskite structure and thus successfully mitigating the poisoning effect of Cr on the electrocatalytic activity and electrical conductivity of LSCF. This study offers a new and effective strategy to develop highly tolerant and resistant cathodes towards Cr contaminant for SOFCs.
Dependence of Electrical Properties on Thermal Reduction of Protecting Oxides for SOFC Interconnect Applications
Authors: Tsai Shu-Yi , Fung Kuan-Zong , Ni Chung-Ta , Ho Hsin-Chia
Published: February 2020

In this study, plasma sprayed (Mn,Co)3O4 (MCO) coatings with spinel structure are used to form protective layer for metallic interconnects of solid oxide fuel cells.

The temperature during thermal spraying is high enough to change the crystal structure and conductivity of protective oxides. The structure change is caused by the removal of oxygen ions at higher temperature. This behavior is so-called thermal reduction. Furthermore, the transformation of MCO Spinel to a NaCl-type structure causes the degradation in its conductivity by several orders of magnitude. With better understanding and control of thermal reduction and/or phase transformation, it is believed that the proper heat treatment is an adequate method to obtain desired properties for protective oxide.

Thus, the objective of this study is (1) to investigate the influence of thermal reduction on the conductivity and crystal structure; (2) to improve the performance of interconnect through proper annealing at desired temperatures. XRD, SEM, and impedance spectroscopy are used to characterize the protective oxides before and after annealing and thermal reduction.
Hydrogen Generation Via Sodium Borohydride Hydrolysis Using the Graphene Supported Platinum-Ruthenium-Cobalt Catalysts Prepared By Microwave-Assisted Synthesis
Authors: Semasko Miroslav , Tamasauskaite-Tamasiunaite Loreta , Stalnioniene Irena , Zieliene Albina , Vaiciuniene Jurate , Simkunaite-Stanyniene Birute , Selskis Algirdas , Norkus Eugenijus
Published: February 2020

Sodium borohydride is of interest as a source for a hydrogen generation during its catalytic hydrolysis. Various catalysts have been developed for this purpose. In the present study the graphene supported platinum-ruthenium-cobalt catalysts (denoted as PtRuCo/GR) with the different Pt:Ru:Co molar ratios, prepared by means of microwave-assisted synthesis, were used as catalysts towards hydrogen generation via sodium borohydride hydrolysis. The morphology and composition of catalysts were examined using Field Emission Scanning Electron Microscopy and Inductively Coupled Plasma Optical Emission Spectroscopy. Catalytic activity of PtRuCo/GR with the different Pt:Ru:Co molar ratios was determined by measuring the amount of hydrogen generated directly from aqueous alkaline solutions of sodium borohydride and compared with that of Co/GR. The data on hydrogen generation volume with respect to time at different concentrations of sodium borohydride and different temperatures have been presented.

It has been determined that the PtRuCo/GR catalysts were synthesized with the Pt:Ru:Co molar ratios equal to 1:2:2, 1:1.7:5.6 and 3.5:1:23. The EDX spectra confirm the presence of Pt, Co and Ru nanoparticles in the investigated PtCoRu/GR catalysts.

It was found that the temperature and composition of catalysts have exceptional influence on the rate of hydrogen generation from alkaline sodium borohydride solutions. Significantly greater hydrogen generation rate is obtained at the synthesized PtRuCo/GR catalysts as compared with that at Co/GR. Highest rates of hydrogen generation were obtained at 60 oC and are 207.5, 82.8 and 53.1 L min-1 gMtotal
-1 for the PtRuCo/GR catalysts with the Pt:Ru:Co molar ratios equal to 1:2:2, 1:1.7:5.6 and 3.5:1:23, respectively. The activation energy (E
a), determined from the kinetic data, is 45.6, 55.9 and 50.2 kJ mol-1 for PtRuCo/GR with the above mentioned Pt:Ru:Co molar ratios, indicating a high catalytic activity of the synthesized catalysts towards hydrolysis of sodium borohydride.
Neutron Radiography of PEM Water Electrolysis Cells
Authors: Seweryn Jakub , Biesdorf Johannes , Boillat Pierre , Schmidt Thomas J.
Published: February 2020

In the past neutron radiography has been successfully applied to investigate the water transport behavior in polymer electrolyte fuel cells and its influence on overall cell performance [1-2]. The same technique can be also used to visualize the gas and water transport inside working polymer electrolyte membrane (PEM) electrolyzers.

                While it is obvious that under operating conditions, a two phase flow of water and its gaseous splitting products occurs inside the porous layers and the flow channels, it is not clear to what extent this can influence overall electrolysis cell performance. In theory gas bubble formation can block the catalyst surface on the anode, decreasing the overall efficiency In addition, the resulting inhomogeneity of the current density over the active area can lead to a local overheating and membrane damage. Strong attenuation of the neutron beam inside liquid water, as compared to typical electrolyzer materials like steel and titanium, makes neutron radiography a perfect technique to investigate these phenomena.

                Neutron radiograms of PEM electrolysis cells (1 cm2 active area) were obtained at varying working parameters. Our experimental setup is designed to provide maximal imaging capabilities at simulated local conditions which can occur in real scale devices. Special attention will be put to the water – gas transport perpendicular to the porous layer. Figure 1 shows the typical patterns with gradients of water thickness being little dependent on the operating conditions.

                This presentation is intended to provide the fundamentals about both the experimental possibilities as well as the water/gas transport behavior during PEM electrolysis cell operation, stimulating the development of numerical models describing this complex system.

References

[1] P. Boillat, P. Oberholzer, A. Kaestner, R. Siegrist, E.  H. Lehmann, G. G. Scherer and A. Wokaun, J. Electrochem. Soc.
159, F210-F218 (2012).

[2] P. Boillat, G. Frei, E.H. Lehmann, G.G. Scherer,  A. Wokaun, Electrochem. Solid-State Lett.
13(3), B25-B27 (2010).

Figure 1. Image recorded for the dry cell (section A) and the cell with flooded anode (section B). The difference in horizontal and vertical scales results from the use of a tilted detector setup [1].

Section C shows images of cells taken at increasing current density (denoted in bottom - right corner [A cm-2]) with the same configuration as in section A and B. The pixel values have been divided by reference values of the cell with flooded anode – white pixels on anode side corresponds to gas, while black on the cathode side to water.

Figure 1
Redox Flow Battery Membranes with Improved Vanadium-Ion Barrier Properties
Authors: Gubler Lorenz , Nibel Olga , Bonorand Lukas , Schmidt Thomas J.
Published: February 2020

The crossover of active redox species in flow batteries leads to a decrease in the faradaic efficiency and, in case of cells with different species on the positive and negative side, to cross-contamination of the electrolyte solutions. In the all-vanadium redox flow battery (VRB) typically vanadium sulfate in a background electrolyte of sulfuric acid is used as electrolyte. In case of commonly used proton exchange membranes, vanadium species can pass through the electrolyte more or less easily.

In this contribution, an approach to improve the vanadium-ion barrier properties of a membrane is presented, while largely maintaining its area resistance [1]. Ethylene tetrafluoroethylene (ETFE) films of 25 µm thickness were grafted with styrene and acrylonitrile (AN) using the radiation-induced grafting technique. Subsequently, the grafted AN units were amidoximated using hydroxylamine. Amidoxime groups are metal-ion complexing agents. The styrene units were sulfonated to introduce cation exchange sites. The composition of the obtained membranes was analyzed by FT-IR spectroscopy and the elemental distribution by energy-dispersive x-ray spectroscopy (EDX) coupled with scanning electron microscopy (SEM). The key properties of the membranes for the application in the redox flow cell, i.e., vanadium ion permeability and area resistance, were investigated. It was found that the permeability of vanadium ions was effectively reduced by increasing the amount of amidoxime groups in the membrane, while the area resistance, measured in a redox flow cell setup, did not considerably increase.

In this contribution, the key polymer design aspects to tune the ohmic resistance and vanadium barrier properties of the membrane are highlighted, relevant ex situproperties of membranes discussed, and redox cell test data presented to demonstrate the features of the grafted amidoxime membranes compared to Nafion 212.

[1] L. Gubler, O. Nibel, L. Bonorand, European Patent Application EP15154151, Paul Scherrer Institut, 2015

Figure 1
Localised Electrochemical Impedance Measurement Using an Innovative Reference Electrode Array
Authors: Brightman Edward , Engebretsen Erik , Lyu Chao , Hinds Gareth
Published: February 2020

Electrochemical impedance spectroscopy (EIS) is an increasingly popular diagnostic tool for polymer electrolyte membrane fuel cells (PEMFCs) and other electrochemical energy conversion devices. Data are commonly fitted to an equivalent circuit model enabling empirical determination of overpotentials, double layer capacitance, and other key parameters. However, conventional experimental configurations are limited to two-electrode measurements, which rely on the assumption that the anode contribution to impedance is negligible. An additional limitation is that an average response for the whole cell is obtained, whereas it is generally accepted that local inhomogeneity in reactant concentration, water distribution and catalyst utilisation is a significant factor affecting fuel cell durability. The use of segmented cells to obtain a functional map of fuel cell performance is well established, but their application to impedance spectroscopy requires complicated equipment and expensive hardware.

Here we report the first localised EIS measurements in a single cell PEMFC using an innovative reference electrode array developed at NPL. By making contact directly with the electrode of interest using a Nafion tube salt bridge inserted through the end plates of the cell, the NPL reference electrode gives an iR-free, localised potential measurement, with the advantage that commercial MEAs can be tested directly with minimal modification to cell hardware. An array of reference electrodes is used to measure the spatial variation in impedance across the active area of the cell under a range of operating conditions, before and after accelerated aging of a commercial MEA. The advantages and disadvantages of this technique and the implications for modelling and optimisation of fuel cell design are discussed.
Use of Hybrid Cathodes to Reduce Platinum Content in High Temperature Proton Exchange Membrane Fuel Cells (HT-PEMFCs)
Authors: Pavlicek Ryan , Strickland Kara , Mukerjee Sanjeev
Published: February 2020

An investigation into the development and use of hybrid cathodes in high temperature proton exchange membrane fuel cells was undertaken.  Previously, non-pgm materials had been developed for use as oxygen reduction catalysts in proton exchange membrane fuel cells[1, 2].  Compared to platinum, long term durability of these non-pgm materials at the elevated temperatures associated with high temperature fuel cells is negatively impacted by the low active site density.  In this work, these non-pgm materials are combined with low platinum loadings in order to take advantage of the high activity of the non-pgms as well as the high active site density of platinum.  This reduction of platinum content allows for a drastic reduction in the price of membrane electrode assemblies (MEAs).  Additionally, these non-pgm materials have shown very high tolerance towards phosphate poisoning (Figure 1) when compared to platinum[3].  Hybrid cathodes were fabricated and used in conjunction with proprietary membranes (TPS Membrane, Advent Technologies) and operated between 160°C and 180°C in order to evaluate performance and stability.

Acknowledgment:

The authors gratefully acknowledge the financial support from the Department of Energy-Energy Efficiency and Renewable Energy, Fuel Cell Technology Office under an Incubator grant (DE-EE0006965).  Use of the Stanford Synchrotron Radiation Light source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Use of Beamline 2-2 at SSRL was partially supported by the National Synchrotron Light Source II, Brookhaven National Laboratory, under U.S. Department of Energy Contract No. DE-SC0012704. Use of the beamline 9-BM in Advanced Photon Source, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357. MRCAT operations are supported by the Department of Energy and the MRCAT member institutions. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

References

1.            Strickland, K., et al., Highly active oxygen reduction non-platinum group metal electrocatalyst without direct metal-nitrogen coordination. Nat Commun, 2015. 6.

2.            Serov, A., K. Artyushkova, and P. Atanassov, Fe-N-C Oxygen Reduction Fuel Cell Catalyst Derived from Carbendazim: Synthesis, Structure, and Reactivity. Advanced Energy Materials, 2014. 4(10): p. n/a-n/a.

3.            He, Q., et al., Mitigating Phosphate Anion Poisoning of Cathodic Pt/C Catalysts in Phosphoric Acid Fuel Cells. The Journal of Physical Chemistry C, 2013. 117(10): p. 4877-4887.

Figure 1
Supercapacitive Properties of Composite Electrode Consisting of Activated Carbon and Di(1-aminopyrene)Quinone
Authors: Kim Kwang Man , Yoon Choong Sup , Park Jeong Ho , Ko Jang Myoun
Published: February 2020

Di(1-aminopyrene)quinone (DAQ) as a quinone-containing conducting additive was synthesized from a solution reaction of 1-aminopyrene and hydroquinone. To utilize the conductive property of DAQ and its compatibility with activated carbon, a composite electrode for a supercapacitor was also prepared by blending activated carbon and DAQ (3:1 w/w), and its supercapacitive properties were characterized based on the cyclic voltammetry and galvanostatic charge-discharge. As a result, a composite electrode adopting DAQ exhibits superior electrochemical properties such as a higher specific capacitance of up to 160 F g-1 at 100 mV s-1, an excellent high-rate capability of up to 1000 mV s-1, and a higher cycling stability with a capacitance retention ratio of 82% for the 1,000th cycle.
Single-Ion-Conducting Glass-Polymer Hybrid Electrolytes for Lithium Batteries
Authors: Villaluenga Irune , Wujcik Kevin , Tong Wei , Devaux Didier , Wong Dominica H.C. , DeSimone Joseph M. , Balsara Nitash P
Published: February 2020

Electrolytes used in lithium-ion batteries that power personal electronic devices and electric vehicles comprise lithium salts dissolved in flammable organic liquids. Catastrophic battery failure often begins with the electrolyte decomposition and combustion. Mixtures of liquids and salts have additional limitations. The passage of current results in an accumulation of salt in the vicinity of one electrode and depletion close to the other electrode, because only the cation participates in the electrochemical reactions. These effects are minimized in the case of single-ion-conducting-solid electrolytes due to the absent of concentration polarization and the limited solubility and slow diffusion (1). Therefore, non-flammable single-ion-conducting solid electrolytes have the potential to dramatically improve safety and performance of lithium batteries (2,3). Solid electrolytes such as inorganic sulfide glasses (Li2S–P2S5) are single-ion-conductors with high shear moduli (18-25 GPa) and high ionic conductivity (over 10−4S/cm) at room temperature (4,5). However, these materials, on their own, cannot serve as efficient electrolytes as they cannot adhere to moving boundaries of the active particles in the battery electrode as they are charged and discharged.

In this study, we describe hybrid single-ion-conducting electrolytes based on inorganic sulfide glasses and perfluoropolyether polymers for lithium batteries. Herein, it is demonstrated that hybrid electrolytes provide a compelling alternative to the traditional glass, ceramic, or polymer battery electrolytes. These electrolytes present high transference numbers, unprecedented ionic conductivities at room temperature, excellent electrochemical stability, and limit the dissolution of lithium polysulfides. The results in this work represent a significant step toward addressing the challenges of enabling the next generation cathodes such as lithium nickel manganese cobalt oxide and sulfur.

_______________________

[1] J.M. Tarascon, M. Armand, Nature, 414 (2001) 359-367.

[2] R. Bouchet, et al., Nature Materials, 12 (2013) 452-457.

[3] N. Kamaya, et al., Nature Materials, 10 (2011) 682-686.

[4] Z. Liu, et al., Journal of the American Chemical Society, 135 (2013) 975-978.

[5] A. Sakuda, A. Hayashi, Y. Takigawa, K. Higashi, M. Tatsumisago, Journal of the Ceramic Society of Japan, 121 (2013) 946-949.
Thermal Analysis and Modeling of an Ultracapacitor Module
Authors: Koo Boram , Park Sung June , Yi Jaeshin , Shin Chee Burm , Choi Jongrak , Lee Ha-Young
Published: February 2020

Electricity generated from renewable sources such as wind and solar power is intermittent. Electrical energy storage devices are therefore critical for effectively leveling the intermittent nature of renewable energy sources. Ultracapacitors (UCs), also known as supercapacitors, have the potential to meet the power requirements for the grid-scale renewable energy storage systems. As compared to batteries, UCs offer a higher power density, higher efficiency, and longer shelf and cycle life. Because the performance of UC depends on temperature, it is important to calculate accurately the thermal behaviors of an individual UC cell in the module composed of multiple UC cells for the efficient and reliable systems integration of UC in grid applications.

In this work, modeling is performed to study the thermal behaviors of the module composed of 18 UC cells. The thermal behaviors of the ultracapacitor cells in the module are measured during the charge/discharge cycling of the ultracapacitor module with constant-current. The charge/discharge current values examined are 50, 100, 150, and 200 A. The validation of the modeling approach is provided through the comparison of the modeling results with the experimental measurements.

Fig. 1 shows the schematic diagram of the ultracapacitor module composed of the 18 ultracapacitor cells (3.7V/3000F) from LS Mtron Ltd. (Anyang, Republic of Korea). The red dots with numbers in Fig. 1 indicate the positions for thermocouple measurement. In Fig. 2, the variations of surface temperature with time from the modeling are compared with those from the experiment during the charge-discharge cycles with the constant current of 200 A. The modeling results shown in Fig. 2 are in good agreement with the experimental measurements.

Figure 1
Synthesis and Characterization of Cross-Linked Anion Exchange Membrane Materials Based on Poly(p-phenylene)s for Redox Flow Battery Applications
Authors: Lee Jang Yong , Cha Min Suc , Kim Tae-Ho , Yoon Sangjun , Hong Young Taik
Published: February 2020

Recently, the most commonly used membrane in vanadium redox flow battery(VRFB) are ion exchange membrane, especially, cation exchange membrane. The state-of-the-art perfluorosulfonic acid polymers, Nation®, are widely used because of their outstanding ion conductivity and chemical stability. However, high cost and vanadium crossover have limited the commercialization of VRFB technology.

Dislike cation exchange membrane, anion exchange membrane has been widely investigated because it could fundamentally decrease permeability of vanadium ions. Nevertheless, the high level of difficulty and low mechanical property have been considered as major obstacles to the practical use of AEM in RFB applications.

In this study, we synthesized hydrocarbon-based AEM materials by Ni(0)-catalyzed coupling polymerization. In addition, synthesized polymers were simply crosslinked by diamine-based cross-linker in order to improve their physical property. We have investigated their physical properties, vanadium crossover and VRFB performance.
Novel Electrolytes for Low-Temperature Electrochemical Energy Storage Devices
Authors: Meng Ying Shirley , Rustomji Cyrus Sam , Yang Yangyuchen , Kim Taekyoung , Caldwell Elizabeth , Yoon Hyojung
Published: February 2020

There are numerous markets (Aerospace, High-Atmosphere and Automotive) requiring energy storage devices with high performance at low-temperatures. Performance of conventional devices (i.e. Li-Ion Batteries, Electrochemical Capacitors) is currently limited at low-temperatures primarily due to the electrolyte. Current Li-Ion technology necessitates the use of particular electrolyte solvents which are highly viscous and have relatively low electrolytic conductivity, preventing high performance below -20 °C. Further, Electrochemical Capacitors commonly use a highly flammable and toxic electrolyte for performance down to -40 °C and a replacement electrolyte is highly sought. Using novel solvents for Low-Temperature electrochemical energy storage devices, high performance of both Li-Ion Batteries and Electrochemical Capacitors at temperatures as low as -60 °C and -75 °C, respectively, has been demonstrated. Novel mechanisms for the superior ionic conductivity in these solvents has been studied as well as the electrochemical stability at high potentials, possibly increasing the energy density of devices. Lastly, these novel solvents are non-toxic and have low flammability, improving the safety aspects of electrochemical energy storage devices.
Improved Electrochemical Performance of Lithium-Sulfur Batteries Using a Modified Separator Coated with Ca(OH)2 and Acetylene Black
Authors: Shao Hongyuan , Huang Yaqin
Published: February 2020

Abstract

Lithium-sulfur (Li-S) batteries have been considered as a promising candidate for next-generation energy storage devices, owing to the extremely high theoretical specific capacity and energy density of sulfur. However, the shuttle effect of lithium polysulfide hampered its commercial application. Recently, more and more attentions have been focused on designing the modified separator with physical and chemical absorption of polysulfide.

In this work, Ca(OH)2 and acetylene black (AB) had been successfully used to design a functional separator for Li-S batteries. The results indicated that Ca(OH)2-AB coated separator could effectively constrain the shuttle effect of polysulfides. In Figure 1, the first upper plateau discharge capacity is 410 mA h g-1 approaching 97.8% of the theoretical value (419 mA h g-1) after coating Ca(OH)2 and AB into common separator, indicating that the polysulfide diffusion is effectively limited. After 100 cycles, the batteries with Ca(OH)2-AB coated separator remains 82.3% of the theoretical value, while the batteries with AB coated and common separators only retain 65.6% and 38.7%. The enhanced upper plateau capacity demonstrates that Ca(OH)2 can effectively trap the polysufides and inhabit the shuttle effect.

Acknowledgements

Financial support from the National Science Foundation of China (No. 51272017) is gratefully appreciated.

Notes

a

State Key Laboratory of Chemical Resource Engineering, Beijing Laboratory of Biomedical Materials, Beijing University of Chemical University of Chemical Technology, Beijing 100029,
People’s Republic of China.

* E-mail: huangyq@mail.buct.edu.cn; Fax: +86 10 6443 8266; Tel: +86 10 6443 8266.

Figure 1. Upper plateau discharge capacities of batteries employing different separators.

Figure 1
Effect of Aging on the Mechanical Properties of Li-Ion Cell Components
Authors: Cao Lei , Zhang Chao , Santhanagopalan Shriram , Pesaran Ahmad
Published: February 2020

Lithium-ion batteries have been widely used as excellent energy storage devices for many applications, recently in development of electric vehicles (EVs). Challenges in both material and mechanical stability inside battery cells/packs have to be overcome to meet an expected EV lifetime of 10-15 years, which requires up to 3000 deep cycles for battery cells and packs, in addition to the safety requirements.[1] Here we present the results from a systematic investigation combining experimental and modeling approaches to compare mechanical integrity of fresh and aged cell components. Samples were collected from two identical commercial cells containing graphite anode and lithium-nickel-cobalt-manganese oxide cathode, with and without 3000 1C/1C cycles at 45 oC. Mechanical response was measured for the anode, cathode and separator using tensile and compression tests. This data set was used to extract constitutive properties of the individual layers, using an approach we published recently.[2] Implications for electrochemical performance of the cell will be discussed.

References:

1. T. Nagaura, K. Tozawa, Progress in Batteries and Solar Cells 9 (1990) 209-217.

2. C. Zhang, S. Santhanagopalan, M.A. Sprague, A. Pesaran, J. Power Sources 290 (2015) 102-113.
A Realistic Model of Mediator Supercapacitors in Micrometer Level
Authors: Wang Yuchen , Zhou Xiangyang , Zhang Chen , Qiao Xiaoyao , Karkkainen Ryan L , Robertson James , Jorge Kevin
Published: February 2020

Solid-state Mediator supercapacitors (SCs) are supposed to provide a high specific energy (25-30 Wh/kg) and high specific power (10-25 kW/kg). In addition, they are shape-flexible, hazard-free, and temperature insensitive. Mediator supercapacitors can be made into dual functional structural materials that store energy and endure mechanical loads. It is thus sensible to research the response of electrochemical processes to mechanical load and vice versa the response of mechanical properties to electrochemical processes. In the present research, a realistic model in the micrometer level is created with realistic geometries of the components including carbon fibers, carbon powders, solid polymer electrolyte, and mediator particles. The 3D model is shown as Figure 1. The realistic model is solved using COMSOL Multiphysics. The simulation describes the equilibrium process of the potential difference between the electrode phase and electrolyte phase under pressure. The total current of mediator supercapacitor increases with increasing pressures due to the increase of ionic conductivity of the electrolyte. The total current of mediator supercapacitor becomes constant at extremely high pressure because the supercapacitor is short circuit. Figure 2 is the design of the system which is used for evaluating the response of electrochemical properties of mediator supercapacitor to mechanical load. Through plane electrochemical impedance spectroscopy (EIS) analysis under different pressures is carried out. The experimental data show that the resistance dependence on the pressure agrees well with the modeling results. As such, the model can be used to design structural supercapacitors as structural components in an engineering system and predict the performance the structural supercapacitors under mechanical loading.

Figure 1
Electrochemical Deposition of MoS2 Thin Films for Energy Storage Applications
Authors: Falola Bamidele Daniel , Suni Ian Ivar
Published: February 2020

Energy storage addresses the problem of sustainability for renewable but intermittent energy sources like solar, wave and wind power. Electrochemical supercapacitors represent a new technology that helps meet the demands for high power and energy density for the optimal storage of renewable but intermittent energy sources. For inclusion in supercapacitors, transition metal oxide and sulfide electrodes such as RuO2, IrO2, TiS2, and MoS2 exhibit rapid faradaic electron–transfer reactions combined with low resistance.

The pseudocapacitance of RuO2 is about 720 F/g and is 100 times greater than the double-layer capacitance of activated carbon electrodes. However syntheses of these oxide and sulfide electrode materials can be expensive and are not presently in commercial use. We report cathodic electrodeposition of molybdenum disulfide onto glassy carbon electrodes from electrolytes containing 10 mM (NH4)2MoS4 and 0.2 M KCl. Four minutes of electrodeposition yields compact 1 µm thick MoS2 film deposit, as confirmed by SEM/EDX analysis, whereas longer deposition times yields much thicker MoS2 film but with nanoscale cracks.

The film capacitance is studied as a function of bulk film thickness and crystallinity. X-ray diffraction analysis demonstrates crystallization of MoS2 after annealing in Ar at 600°C for 1 hr. The electrochemical performance of both amorphous and crystalline MoS2 films is studied in 1 M TEA-BF4 in acetonitrile by electrochemical impedance spectroscopy, cyclic voltammetry and chronocoulometry. The films demonstrate stable pseudocapacitive behavior; for both the amorphous and annealed films, with specific capacitances of 40 F/g and 300 F/g, respectively. Studies as a function of MoS2 thickness demonstrate that the capacitance eventually plateaus’, suggesting that only the near-surface region is available for charge storage. Results will also be presented for electrochemical impedance spectroscopy and atomic force microscopy of these films before and after capacitance cycling.
Incremental Impedance Technique for Determining Optimal Capacity Control Limits in C-Si Composite Batteries
Authors: Blaser Rachel , Murray Daniel , Karulkar Mohan
Published: February 2020

It is well known that limiting the cycling SOC of a battery material leads to improved cycle life.1  Determining optimal cycling limits, however, can be an expensive trial-and-error process. Candidate voltage or capacity limits must be proposed and tested, with tests consisting of capacity face measurements over large numbers of cycles, perhaps even at various cycling rates. A more efficient method is to identify a quantifiable phenomenon that manifests early in a cell’s cycle life, and which accurately indicates an SOC range for optimal cycling.  In the current work, we use an Incremental Impedance technique to identify critical impedance jumps that serve as markers for optimal SOC limits, detectable from a cell’s very first post-break-in cycle.

To determine an optimal SOC (“Capacity Control”) range for cycling, a five-cycle Incremental Impedance scan was conducted on in-house C-Si anodes, formulation A (PVDF binder, 5 mg/cm2 loading). Figure 1 shows a distinct jump in impedance was observed at 70% SOC during lithiation, and indicates 0-70% as a promising SOC range for cycling.

Based on the Incremental Impedance analysis,  cycling was done with SOC cutoffs of 60, 80, and 100%, to probe around the 70% point. Figure 2 shows a 60% SOC cutoff improves cycle life over 80%, while 80% and 100% (full cycling) display similar fade characteristics. 70% SOC is thus a key “point of no return” for SOC limiting.

The technique was repeated for formulation B (CMC/SBR binder, 2 mg/cm2 loading). Results in Figure 3 show that both produce the same sharp increase  in impedance at 70%, independent of binder type and loading.

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1Mohan Karulkar, Rachel Blaser, Bob Kudla, Automotive assessment of carbon–silicon composite anodes and methods of fabrication, Journal of Power Sources, Volume 273, 1 January 2015, Pages 1194-1201

Figure 1
The Effect of a-Site and B-Site Substitution on BaFeO3-δ: An Investigation As a Cathode Material for Intermediate-Temperature Solid Oxide Fuel Cells
Authors: Wang Jian , Ciucci Francesco
Published: February 2020

Solid oxide fuel cells (SOFCs) are widely thought to be among the most promising energy conversion devices due to their low environmental impact, high efficiency and fuel flexibility. BaFeO3-δ
(BFO) stands out as one of the most electrochemically active iron-based SOFC cathodes. This work systematically investigates the effects of single A-site dopant (5 mol% La3+, Sm3+ and Gd3+) and single B-site dopant (5 mol% Zr4+ and Ce4+) on the structure and oxygen reduction reaction of BFO used as a cathode for SOFCs. The materials are prepared by solid-state method and their structural, electronic, electrocatalytic properties are characterized and compared. X-ray diffraction reveals 5 mol% A-site or B-site dopant is sufficient to stabilize the cubic phase of BFO, as predicted by the lattice calculation. X-ray photoelectron spectroscopy and iodometric titration demonstrates that neither of the two doping sites has obvious advantage over the other towards the formation of additional oxygen vacancies. B-site doped BFO shows a lower electrical conductivity than A-site doped ones, however, they have much quicker response to electrical conductivity relaxation, likely originating from the expanded lattice size. With the largest oxygen vacancy concentrations, Ba0.95La0.05FeO3-δ and BaFe0.95Zr0.05O3-δ stand out from the A-site and B-site doped BFO, respectively, and polarization resistances of 0.029 Ω cm2 and 0.020 Ω cm2 are achieved at 700 °C, . With a similar amount of oxygen vacancies, B-site doping is more advantageous for enhancing oxygen bulk diffusion kinetics, and thus ORR activity.
(Invited) Electrochemical Synthesis of Multiadducts from [60]Fulleroindolines
Authors: Wang Guan-Wu
Published: February 2020

[60]Fulleroindolines can accept two electrons to form the corresponding dianions, which involve the heterolytic cleavage of the C60－N bond. The ring-opened structures are perfect building block for the further functionalizations. The synthesis of both tetrafunctionalized and hexafunctionalized products with unusual addition patterns have been achieved.[1]

References

[1]. Xiao, Y.; Zhu, S.-E; Liu, D.-J.; Suzuki, M.; Lu, X.; Wang, G.-W. Angew. Chem. Int. Ed.
2014, 53, 3006-3010.