bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study on the Conductivity and Selectivity of Lithiated Nafion Membranes in Non-Aqueous Electrolytes
Authors: Su Liang , Darling Robert M. , Gallagher Kevin G. , Xie Wei , Thelen Jacob L. , Balsara Nitash P. , Brushett Fikile R. 
Published: February 2020

ABSTRACT
In a range of electrical energy storage technologies, redox flow batteries (RFBs), which reversibly convert chemical energy to electrical energy, have shown a favorable balance of cost, safety, and performance for stationary applications. Shifting from aqueous to non-aqueous electrolytes may promise a higher cell voltage due to the extended electrochemically stable window (~ 4 V) and an enriched selection of redox materials due to the broader variety of organic solvents [1]. As a key component in RFBs, an ideal membrane should have negligible electronic conductivity, high ionic conductivity, good chemical stability and mechanical strength, and low active species crossover. However, to date, no non-aqueous membrane has been identified that simultaneously fulfills these requirements, especially high ionic conductivity and low crossover rate.
To meet aggressive established cost targets ($120/kWh), our recent work suggests the maximum area-specific resistance for non-aqueous RFBs is 2.3 Ω ∙ cm2, which corresponds to the ionic conductivity of 1.1 mS/cm and 7.7 mS/cm for a membrane with a thickness of 25.4 µm (such as Nafion® 211) and 177.8 µm (such as Nafion® 117), respectively [2]. However, there is little data on the effectiveness of successful aqueous membranes under non-aqueous conditions. To this end, we explore the performance of lithiated Nafion 117 (Li N117) in non-aqueous electrolytes with a focus on the relationships between ionic conductivity, species selectivity, and membrane microstructure. Key membrane properties and performance metrics are quantified in electrolytes consisting of different salt and solvent combinations. Species crossover is studied using model compounds with positive, neutral, and negative charge. Membrane microstructure is probed using Small Angle X-ray Scattering and solvent permeability measurements. Results indicate a critical relationship between pore size, ionic conductivity and species selectivity and provide guidance for future research directions in non-aqueous separations.
ACKNOWLEDGEMENTS
This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.
REFERENCES
[1]. R. Darling, K. Gallagher, J. Kowalski, S. Ha and F. Brushett. Energy & Environmental Science, vol. 7, no. 11, pp. 3459-3477, 2014.
[2]. R. Darling, K. Gallagher, W. Xie, L. Su and F. Brushett. submitted manuscript
Pseudocapacitive Carbon Nanofibers Using Sodium Chloride (a.k.a common salt)
Authors: Singhal Richa , Kalra Vibha 
Published: February 2020

Pseudocapacitors have gained attention due to their higher achievable energy densities than electric double layer capacitors. The most studied pseudocapacitive materials are transition metal oxides such as RuO2, MnO2, etc. and conducting polymers such as polyaniline and polypyrrole. However, these materials present some important drawbacks such as they are expensive, operate in a low voltage window, cause decomposition of the electrolyte, or have poor stability. An alternative approach is the surface modification of carbon materials to include functional groups, which can participate in pseudofaradaic charge transfer reactions and maintain the high cyclability of supercapacitors.
A novel and simple method of incorporating pseudocapacitive surface functionalities on free-standing carbon nanofibers using common salt (sodium chloride (NaCl)) is presented. NaCl enhances capacitance by modifying carbon surface functionalities, while still keeping intact the free-standing matrix of carbon nanofibers. The blend of sodium chloride and polyacrylonitrile is electrospun together, followed by pyrolysis and mild acid treatment to obtain functionalized free-standing (binder-free) carbon nanofibers. The synthesized materials have a low surface area of only 24 m2 g-1, however the electrochemical studies show a five-fold increase in specific capacitance on incorporation of NaCl (CNF-13) compared to that without NaCl (CNF-0) (Fig.1). The XPS characterization demonstrates that the presence of NaCl leads to enhanced oxygen on the surface of carbon nanofibers, particularly in the form of carboxyl groups. These carboxyl groups then facilitate the adsorption of sulfur functional groups on acid treatment. A high specific capacitance of 204 F g-1, areal capacitance of 1.15 F cm-2, and volumetric capacitance of 63 F cm-3 in 1 M H2SO4 are obtained, which are attributed to the surface functional groups participating in the pseudocapacitive redox reactions. The fabricated nanofibers demonstrate good capacitance retention at high current densities (57% at 20 A g-1) and high cyclability.
Fig. 1 Cyclic voltammograms of the treated carbon nanofibers in 1 M H2SO4 using a two-electrode test cell at a scan rate of 5 mV s-1.
References:

R. Singhal and V. Kalra, J. Mater. Chem. A, 2015, 3, 377–385.

Figure 1
Probing the Mechanical Deformation of 2D Titanium Carbide (MXene) upon Cation Intercalation at the Nanoscale
Authors: Come Jeremy , Black Jennifer , Naguib Michael , Lukatskaya Maria R. , Beidaghi Majid , Gogotsi Yury , Kalinin Sergei V. , Balke Nina 
Published: February 2020

The titanium carbide Ti3C2
Tx
(where Tx
stands for termination functions at the surface such as –OH, =O, and –F) is a member of the recently discovered family of two-dimensional (2D) materials known as MXenes. This material demonstrates a high intercalation capacitance related to the rapid transport of ions within the structure, making this a promising electrode material for supercapacitors.[1] To date however, the intercalation mechanism is poorly understood and other techniques able to probe the dynamics are required. In this work, in-situ Atomic Force Microscopy is used to monitor the strain developed in a Ti3C2
Tx
electrode during intercalation/extraction of monovalent and divalent cations in a variety of aqueous electrolytes. Interestingly, the electrode undergoes a large contraction during Li+, Na+ or Mg2+ intercalation, differentiating the MXene paper from conventional electrodes where redox intercalation of ions (e.g. Li+) into the bulk phase (e.g. graphite, silicon) results in volumetric expansion. The relative deformation amplitude strongly depends on the cation radius and electric charge ranging from almost no change to over 15% of shrinkage.[2] This feature may explain the excellent rate performance and cyclability reported for MXenes.The unique mechanical changes induced by the presence of cations between the layers were investigated by Contact Resonance Piezoresponse Force Microscopy. Spatial mapping of the resonance frequency with high resolution showed that the elastic modulus of the carbide increases when Li+ ions are intercalated, in good agreement with the strong interactions between MXene sheets that leads to contraction. Furthermore, it revealed that the cation intercalation preferentially occurs at the shallow sites of the MXene flakes.
These results are exciting because they shed light on the intricate interplay of the MXene mechanical properties with the electrochemical performance. Moreover, they show that the cation dynamics in the confined 2D spaces can be efficiently probed with in-situ AFM techniques.

References

[1] M. Ghidiu et al., Conductive Two-Dimensional Titanium Carbide ‘Clay’ with High Volumetric Capacitance, Nature, 2014, 516, 78-82

[2] J. Come et al., Controlling the Actuation Properties of MXene Paper Electrodes upon Cation Intercalation, Nano Energy, under review.
Unveiling the Pseudocapacitance of Ti2C Monolayer for High Performance Electrochemical Capacitor: a First-Principles Study
Authors: Ji Xiao , Jiang Jianjun 
Published: February 2020

Two-dimensional (2D) transition-metal (TM) compound nanomaterials have been widely investigated for electrochemical capacitor due to their high-surface-area and large potential of providing pseudocapacitance. Very recently, a new family of 2D materials called MXenes were synthesized and have been considered as one of the most promising pseudocapacitor electrode materials with respect to both power density and energy density. In this work, we employ first-principles calculations to study the electronic structures and redox potential and diffusion of Li on Ti2C monolayer, a representative MXene, based on density functional theory (DFT). The electronic structures indicate a significant redox pseudocapacitance characteristics as an anode with the redox potential at about 0.25 V and 0.75 V refer to the standard hydrogen electrode. Moreover, the calculated metallic behavior and low Li ions diffusion barriers suggest that Ti2C monolayer would manifest a low resistance in charging/discharging process. Our findings provide an evidence that the Ti2C monolayer is a promising electrochemical capacitor electrode material.
Figure a shows the crystal structure of Ti2C monolayer in the top view and side view. The Ti and C are revealed by yellow and blue spheres, respectively. On the top view, the lighter yellow spheres consist of the first layer with the third layer formed by dim ones. Relative dispositions of PDOS and Integral DOS of d-orbitals of Ti atoms in Ti2C monolayers are shown in Figure b both on the vacuum scale and with respect to the SHE reference. The dot dashed red lines indicate the Fermi level positions of Ti2C monolayer. The light blue region represents the electrolyte window. To deliberate the diffusion of Ti2C monolayer, three pathways (Figure c) and corresponding energy barriers (Figure d) are considered.

Figure 1
Facile Hydrothermal Synthesis of Feather-like Nickel Phosphite As Cathode Materials for Supercapacitors
Authors: Ruan Yunjun , Jiang Jianjun , Wan Houzhao 
Published: February 2020

Recently, supercapacitors have attracted plenty of attentions, due to its high power density, long cycling lifespan and excellent stability. According to the charge storage mechanism, supercapacitors can be divided into double layer capacitors and pseudocapacitors. Moreover, the pseudocapacitors depend on faradic reaction and can result in much higher specific capacitance than double layer capacitors. For instance, nickel-based compounds exhibit outstanding performance reported in many literatures.
In this work, we successfully synthesize the feather-like nickel phosphite via a facile hydrothermal route at 200 ℃ for 24 h, employing Ni(NO3)2 as nickel source, sodium pyrophosphate as phosphorus source and the mixture of deionized water and glycol as solvent. The diffraction peaks of the product are well matched with the standard diffraction patterns of the orthorhombic Ni(HPO3) (H2O) (JCPDS NO. 01-082-0075) as shown in Figure 1a. The SEM image in Figure 1b reveals the morphology of the sample is feather-like structure.
Figure 2a exhibits cyclic voltammetry curves of the nickel phosphite in 6 M KOH electrolyte at different scan rate from 1 to 50 mV s-1, which indicates the electrode is highly reversible with excellent electrochemical capability and redox processes. The galvanostatic charge-discharge curves measured at different current densities are shown in Figure 2b. The corresponding specific capacitance values of the nickel phosphite are calculated from the discharge curves as shown in Figure 2c. Figure 2d shows the Nyquist plots of the nickel phosphite. Therefore, the nickel phosphite were good candidates for high performance energy storage.

Figure 1
Possibility of Methane Production from Steam and Carbon Dioxide by Using Solid Oxide Electrolysis Cells
Authors: Kato Tohru , Nagata Susumu , Honda Takeo , Negishi Akira , Tanaka Yohei , Momma Akihiko 
Published: February 2020

To overcome global warming issue and energy shortage problem, economical hydrogen production technologies from renewable energy or unused fossil fuel with carbon capture technology are being developed all over the world. However it becomes the large problem that it is necessary to reconstruct energy infrastructures for production, transportation and usage of hydrogen and to entail a vast cost.
Against this problem, for effectively utilizing existing energy infrastructures, we are developing a methane producing technique from water and carbon dioxide by using renewable electricity instead of hydrogen production. Specifically, solid oxide electrolysis cell (SOEC) technology for producing syn-gas with high efficiency has been developed and we have succeeded in trial manufacture tubular SOECs whose sin-gas production rate is more than 3.5 sccm/cm2 at the operating temperature of 750 oC and electrolytic voltage of 1.35V.
Therefore, in this paper, the numerical models of an SOEC methane production system and a conventional methane production system were made in reference to performance of the tubular SOECs and dependence of performance of the each system on operating conditions, such as operating temperature, feed gas composition, is analyzed and compared with each other.
The methane producing system which combined a water electrolysis system with a high temperature water-gas shift reactor was considered as a conventional system.
From the result of the analysis, advantage of SOEC methane production system is clarified.
Influence of La/Pr Ratio on the Ageing Properties of La2-X
Pr
x
NiO4+δ as Cathodes in IT-SOFCs
Authors: Vibhu Vaibhav , Bassat Jean-Marc , Flura Aurélien , Nicollet Clément , Grenier Jean-Claude , Rougier Aline 
Published: February 2020

The present study is focused on alternative oxygen electrodes for Intermediate Temperature Solid Oxide Fuel Cells (IT-SOFCs) using Metal Supported Cells (MSCs) conditions. To prevent detrimental oxidation of the metal support, sintering of the cell components at high temperature under low pO2 is required. Ln2NiO4+δ (Ln = La, Pr) compounds with the K2NiF4-type structure act as cathode materials for IT-SOFC due to their mixed ionic and electronic conductivity (i.e. MIEC properties). Pr2NiO4+δ shows excellent electrochemical properties at intermediate temperature (i.e. low polarization resistance Rp
value, Rp
= 0.03 Ω.cm² at 700 °C), while La2NiO4+δ exhibits higher chemical stability. Thus, the properties of La2
-x
Pr
x
NiO4+δ mixed nickelates were investigated with the aim to find best compromise between chemical stability and electrochemical performances.
Herein, the chemical stability of the nickelates under air at operating temperatures as well as the evolution of the polarization resistances during ageing (recorded under air at idc
= 0 and idc
≠ 0 conditions) were studied for duration up to one month. La2NiO4+δ is chemically stable whereas Pr2NiO4+δ dissociates after 1 month at 600, 700 and 800 °C. At idc
= 0 condition, the ageing of the half cells during 1 month under air shows no change in Rp
, despite their various degrees of chemical stability. A different behavior is observed under idc
≠ 0 conditions with a large increase in Rp
for Pr-rich phases in SOFC mode while interestingly, Rp
remain stable in SOEC mode. In this presentation, the electrochemical properties of La2
-x
Pr
x
NiO4+δ under ageing and postmortem analysis will be discussed in details.
Microtubular SOFC (mSOFC) System in Truck APU Application
Authors: Kendall Kevin , Newton Jill , Kendall Michaela 
Published: February 2020

One of the most sought after applications for small-scale SOFCs has been the Auxiliary Power Unit (APU) for trucks. A mSOFC could provide heat for the cab whilst powering the electrical loads required when the engine is shut down. Significant development efforts have been made by several large companies including Delphi, AVL and Volvo, all using planar configurations with diesel as the fuel. However the planar construction is prone to damage via cracking and use of diesel fuel is known to require problematic reforming. Despite large research funding from SECA and other sources, directed especially toward the 5kWe unit since 2000, there is still no commercial product in the market. The purpose of this paper is to discuss three novel ideas applied to this attractive market area:-

Replacing the planar stacks with mSOFCs to give greater robustness

Downsizing to 100We to allow more rapid evolution

Focusing on dual fuel trucks using LNG as clean fuel for the SOFC

An EU project was initiated in 2014 to develop these ideas under the heading SAFARI (SOFC APUs For Auxiliary Road-truck Installations) funded by FCH-JU with 6 partners in the UK, Spain, Poland and Switzerland. This paper describes results from the first 18 months of the project and shows that mSOFCs operating on LNG can give significant impact in the marketplace.
Direct Ethanol Anode-Supported Solid Oxide Fuel Cell
Authors: Nóbrega Shayenne D. , Steil M. C. , Georges Samuel , Uhlenbruck Sven , Fonseca Fabio C. 
Published: February 2020

Long term durability was demonstrated on high-performance direct ethanol solid oxide fuel cell operating in gradual internal reforming. Anode supported single cells, fabricated at Forschungszentrum Jülich, composed of (La,Sr)MnO3 cathode, 8 mol% yttria-stabilized zirconia (YSZ) electrolyte, and YSZ-Ni anode were used for long term testing on anhydrous (direct) ethanol. Gadolinia-doped ceria (CGO), with 0.1 wt.% of Ir, catalyst was produced by the impregnation of Ir salt in commercial CGO (Praxair) and mixed with organic additives. The CGO-Ir suspension was deposited onto the surface of the YSZ-Ni anode support with an air brush. Such a catalytic layer acts both as a physical barrier to avoid direct contact of the fuel with Ni-based anode and to promote the gradual internal reforming of ethanol. The CGO-Ir catalyst was designed for the reforming of the main compounds resulting from the thermal decomposition of ethanol at high temperature and to inhibit the formation of ethylene, which is a known source of carbon deposits. After deposition the sample was heated at 850ºC in inert atmosphere to ensure good adhesion between the catalytic layer and the anode. Gold grid and paint were used as current collectors in both cathode and anode sides. The single fuel cells were mounted in the test apparatus, sealed with gold rings and alumina cement and heated to the measuring temperature (850°C) under inert atmosphere. After gas tightness was checked by flowing air on the cathode side and argon on the anode side, the anode was reduced under hydrogen. The fuel cell was kept at 0.6 V while monitoring the current drained from the cell at 850 °C. Samples were initially operated in hydrogen for a few hours and fuel was switched to dry ethanol, carried by nitrogen. It is important to mention that no oxidizing agent was added to the fuel and that water produced by the electrochemical reaction of hydrogen at the anode promoted the reforming of the ethanol in the CGO-based layer, in the so-called gradual internal reforming. In such conditions the current output was recorded and observed to not be significantly different form that under hydrogen. Moreover, the direct ethanol fuel cell was continuously operated for 650 hours without major losses due to carbon formation. The experimental results demonstrate that the water released by the electrochemical oxidation of reformate hydrogen at the electrolyte/anode active interfaces is sufficient for the reforming of the primary fuel in the catalytic layer, provided that a minimum fuel utilization is respected. After the durability tests, energy dispersive X-ray spectroscopy and scanning electron microscopy analyses of the samples revealed no carbon deposit formation in the anode. The experimental results provided compelling evidence for the viability of gradual internal reforming of ethanol in high performance solid oxide fuel cells.
The Effect of Mn Co-doping on the Electrochemical Properties of Gd0.2Ce0.8O1.9-
d/Pt Model-composite Electrodes
Authors: Velicsanyi Peter , Gerstl Matthias , Nenning Andreas , Hutter Herbert , Fleig Jürgen , Opitz Alexander Karl 
Published: February 2020

For solid oxide fuel cells (SOFCs) to reach widespread commercial distribution several obstacles still have to be overcome. Material-wise one of the main problems remains the optimization of the anode for use in harsh environments or operation conditions.
The still prevalent anodes based on Ni/YSZ cermets offer excellent catalytic properties for hydrogen oxidation and reformation of hydrocarbon fuels. Nevertheless, when feeding a fuel containing hydrogen sulphide impurities to an SOFC, a dramatic drop in the anode performance is the consequence. Therefore, work is in progress to identify the causes of this sulphur triggered polarization resistance increase, which is partially explained by sulphur adsorption. The hope is that a more complete understanding in this degradation will help to formulate mitigation strategies as a way to prolong the life of an SOFC.
In this contribution alternative SOFC anode materials are being surveyed and compared to the classic Ni/YSZ cermet. By exchanging the ionically conductive YSZ phase with e.g. gadolinium doped ceria (GDC) and/or the electronically conducting nickel with e.g. donor doped strontium titanate, formulations may be found, which increase the sulphur tolerance of an SOFC anode. Moreover, a fully oxidic anode may offer a significantly higher redox cycling stability than the conventional Ni/YSZ cermet.
By using impedance spectroscopy on geometrically well-defined model-composite electrodes of alternative SOFC anode materials, we are able to separate elementary processes such as ionic and electronic conductivity as well as the chemical capacitance and the surface reaction resistance. By introducing H2S in the feed gas system the effects of sulphur poisoning on these parameters can be studied. This way a fair comparison of alternative SOFC anode materials to Ni/YSZ is possible.
Simulation of Interfacial Cracking of the Joint between Glass-Ceramic Sealant and Metallic Interconnect in a Planar Solid Oxide Fuel Cell Stack
Authors: Lin Chih-Kuang , Shiu Wei-Hong , Wu Si-Han , Lee Ruey-Yi 
Published: February 2020

Interfacial cracking in the joint between a glass-ceramic sealant and a metallic interconnect under thermal stresses is characterized for a prototypical planar solid oxide fuel cell (pSOFC) stack, using finite element analysis (FEA). A three dimensional FEA model is constructed for a multiple-cell stack to perform thermal stress analysis at both steady operation and shutdown stages and to locate the highly stressed region in each component. Stress intensity factor and energy release rate for fracture are calculated at the crack front of a crack placed at the highly stressed interfacial region between a glass-ceramic sealant and a metallic interconnect in the given pSOFC stack for each stage. The critical crack or defect size at the interface of the joint of glass-ceramic sealant and metallic interconnect in the given pSOFC stack is determined by comparing the calculated energy release rates with the experimental measurements of interfacial fracture energy of the glass-ceramic/metallic interconnect joint.