bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling Transport Phenomena in Ammonia Fuel Cells
Authors: Suh Dongmyung , Botte Gerardine G , Daramola Damilola A. 
Published: February 2020

Introduction

Ammonia has been considered as a potential fuel for alkaline fuel cells. Ammonia can be produced at low cost, and inexpensive catalysts can be used in Ammonia Fuel Cells (AFC) [1, 2]. In AFC, ammonia is oxidized at the anode side and OH-, nitrogen and water are produced (1). OH- anion moves through membrane and reduced into water at the cathode side (2).
1/3 NH3 + OH- ↔ 1/6 N2 + H2O + e-, E0=0.40V ----- Eqn. 1
1/4 O2 + 1/2 H2O + e- ↔ OH-, E0=0.40V ----- Eqn. 2
The theoretical open-circuit voltage (OCV) of the AFC is 1.17 V at standard conditions. The value is less than that of Hydrogen Fuel Cells (HFC), but AFC has a higher energy efficiency, 88.7%, than HFC of 83% [1].
Performance and durability of hydrogen PEM fuel cells has been improved over the last decade by extensive experiments and computations. In particular, continuum modeling has been an important tool for understanding and insight into processes and phenomena, which cannot be captured through experiments [3].
Recently, AFCs have attracted the attention of fuel cell researchers due to its high potential for a clean future energy device. However, AFCs show some problems in related to mass transfer and fuel crossover in the membrane electrode assembly. In this study, transport phenomena in AFCs are analyzed using a computational model.

Objective

When the AFC is in operation, complex phenomena occur in the Membrane Electrode Assembly (MEA) including mass and heat transfer, electrochemical reactions, and charge (OH- and electron) transport (Fig.1). Therefore, a continuum model was developed to simulate the phenomena in MEA.

Figure 1. Illustration of Mass Transport in Membrane Electrode Assembly depicting individual layers and chemical components. cCL and aCL depict the cathode and anode catalyst layers respectively, while cGDL and aGDL depict the cathode and anode gas diffusion layers respectively.

Results

Using the model, potential and species distribution in MEA, and the extent of electrochemical reaction in catalyst layer were calculated. In addition, the effect of different operating conditions on these phenomena were analyzed. These results, along with the effect of water transfer and ammonia crossover on cell performance will be discussed. Detailed accounts of the governing equations and their numerical solving procedure will also be provided.

References

[1] R. Lan and S. W. Tao, "Direct
Ammonia Alkaline Anion-Exchange Membrane Fuel Cells," Electrochemical and solid State Letters, vol. 13, pp. B83-B86, 2010.
[2] M H. Assumpcao, S.G.Silva, and R. F. Souza, "Direct Ammonia Fuel Cell Performance using PTIR/C as anode electrocatalysts," Int. J. of Hydrogen Enrgy, vol. 39, pp.5148-5152, 2014.
[3] A. Z. Weber, R. L. Borup, "A Critical Review of Modeling Transport Phenomena in Polymer-Electrolyte Fuel Cells," J. of The Electrochemical Society, Vol 161, ppF1254-F1299, 2014

Figure 1
Nitrogen-Doped Graphene/Sulfur Composite As Cathode Material for Room-Temperature Sodium-Sulfur Battery Application
Authors: Hao Yong , Li Xifei , Wang Chunlei 
Published: February 2020

Sodium is a promising alternative anode material with advantages of high abundance, low cost, and suitable redox potential (~2.71 V). Sulfur, as one of the most abundant elements on earth, is considered as an attractive cathode material owing to its high theoretical capacity of 1675 mA h g-1 and high energy density of 2600 W h kg-1. It is well known that sodium-sulfur (Na-S) battery has been widely used for stationary energy storage, operating at a high temperature condition. In recent years, much effort has been devoted to develop Na-S batteries at ambient temperature to overcome the safety drawback [1-3]. However, more challenges exist in room temperature (RT) NaS batteries such as dissolution of intermediate polysulfides into the electrolyte, low utilization of active material, and poor cycle life. In this work, nitrogen-doped graphene nanosheets (NGNS) interlinked with sulfur has been used as an electrode material for RT Na-S batteries. This nanocomposite was synthesized via an chemical reaction-deposition and thermal treatment strategy. Two series samples with both high and low sulfur content levels in the nanocomposites have been developed. Characterizations testing such as SEM, XPS and XRD have been conducted and the results from electrochemical testing show that the first cycle discharge/charge capacities of the low loading sulfur-NGNS composite at 0.05C have been reached 212 mA h g-1 and 181 mA h g-1. The low loading sulfur-NGNS composite also presented notable cycling life with 300 cycles at 0.1C and the capacity remained at 55 mA h g-1, indicating good cyclic retention. Detailed discussion on the characterization and electrochemical performance of the synthesized NGNS/S nanocomposite will be presented in the meeting.

References

1. T.H. Hwang, D.S. Jung, J.S. Kim, B.G. Kim, J.W. Choi, Nano Lett., 13, 4532 (2013).
2. S. Xin, Y.X. Yin, Y.G. Guo, L.J. Wan, Adv. Mater., 26, 1261 (2014).
3. S. Zheng, P. Han, Z. Han, P. Li, H. Zhang, J. Yang, Adv. Energy Mater., 4 (2014).
(Invited) Advantages of the Chloride-Containing All Vanadium Redox Flow Battery System
Authors: Li Liyu 
Published: February 2020

In 2010, a novel all vanadium redox flow battery system was developed at the US Department of Energy’s (DOE) Pacific Northwest National Laboratory (PNNL), with the support of the US DOE Office of Electricity Delivery and Energy Reliability’s Grid Storage Program. This new system uses vanadium electrolyte with chloride-containing supporting solution, in which a stable complex between Cl- and V5+ forms. This new system was proved to have a much improved stability over the traditional sulfate based chemistry in small scales.
In the past three years, this advanced chloride-containin all vanadium redox flow battery system was extensively evaluated at UniEnergy Technologies, LLC (UET). The stability and cell performance of electrolyte solutions with different impurities were tested over a broad temperature window; the performance of kW-scale and large-scale stacks was tested for thousands of cycles under various operation conditions; different testing and prototype systems, from 1 kW, 30 kW, to 100 kW, were developed and thoroughly tested for different applications; etc.
In 2014, the first commercial product of UET, Uni.System™, which delivers 600kW power and 2.2MWh energy in a compact footprint of only five 20’ containers, was successfully developed. This system integrates the abuse tolerant mixed acid vanadium electrolyte; a state-of-the-art containerized design derived from multiple decades of design experience among the UET team; optimized power electronics and controls at each system level (from cell to site); and mature large-scale stacks with more than 7 years of field deployment and over a dozen systems in the field. In early 2015, a 1 MW-4 MWhr system, which consists of two Uni.SystemTM, was deployed in Pullman, WA by a utility company, Avista.
In this presentation, we will discuss what we’ve learned in the past three years about this advanced chloride-containing all vanadium redox flow battery system, especially the unique advantages of this system over the traditional sulfate system, and our understanding on the potential of this novel technology for various energy storage market applications.

Figure 1
Ionic Liquid Electrolytes for Rechargeable Aluminum Batteries
Authors: Wang Huali , Liu Gao , Bai Ying , Wu Chuan , Chen Shi , Wu Feng , Ling Min 
Published: February 2020

Rechargeable aluminum battery is considered as a promising battery system used in energy storage devices, due to its abundant natural resources and high capacity. However, fabrication of this battery working at room temperature didn’t succeed until haloaluminate contained ionic liquids were used as electrolytes. Therefore, electrolytes are expected to have a great effect on performance of rechargeable aluminum battery. For ionic liquid electrolytes, anions play a major role in its electrochemical properties. Anion-effect of haloaluminate contained ionic liquids prepared with different halogenated imidazole salt and AlCl3/imidazolium chloride mole ratio are studied. Electrochemical window is found narrowing with reducibility of halide ion and AlCl3 mole fraction. When used as electrolyte in rechargeable aluminum battery with V2O5 nanowire cathode, AlCl3/[BMIM]Cl ionic liquid with the mole ration of 1.1:1 shows the best performance. The as-assembled cell exhibits a high discharge voltage platform (1 V) and capacity (288 mAh/g) at the first cycle. Concentration of Al2Cl7
- is considered as a key factor in chloroaluminate ionic liquids when used as electrolyte.
A slightly corrosion is found on the surface of Al metal foil immerged in acid AlCl3/[BMIM]Cl ionic liquids after 24 h. It means this kind of ionic liquids may help to remove the oxide film on Al metal foil. The oxide film is considered as a mainly hinder to performance of aluminum battery. Performance of battery using ionic liquid with other anions (such as BF4
-, PF6
- and CF3SO3
-) has not been reported, which is probably due to the dense Al2O3 film formed on surface of Al anode. It prevents the oxidation of Al in discharge process of battery and causes a failure.

Figure 1
Self-Sacrifice Template Formation of Hollow Hetero-Ni7S6/Co3S4 Nanoboxes with Intriguing Pseudo-Capacitance for High-Performance Supercapacitors
Authors: Hua Hui , Chen Qiuliu , Chen Zhiyi , Hou Linrui , Yuan Changzhou 
Published: February 2020

Herein, we report a simple yet efficient self-sacrifice template protocol to smartly fabricate hollow hetero-Ni7S6/Co3S4 nanoboxes (Ni-Co-S NBs). Uniform nickel cobalt carbonate nanocubes are first synthesized as the precursor via solvothermal strategy, and subsequently chemically sulfidized into hollow heter-Ni-Co-S NBs through anion-exchange process. When evaluated as electrodes for electrochemical capacitors (ECs), the resultant hetero-Ni-Co-S NBs visually exhibit attractive pesudo-capacitance in KOH just after contineously cyclic voltammetry (CV) scanning for 100 times. New insights into the underlying energy-storage mechanism of the hollow hetero-Ni-Co-S electrode, based on physicochemical characterizations and electrochemical evaluation, are first put forward that the electrochemically induced phase transformation gradually occurrs during CV sweep from the hetero-Ni-Co-S to bi-component-active NiOOH and CoOOH, which are the intrinsic charge-storage phases for the appealing Faradaic capacitance of hollow Ni-Co-S NBs at high rates (~677 F g-1 at 4 A g-1) after cycling. When further coupled with negative activated carbon (AC), the AC//hetero-Ni-Co-S asymmetric device with extended electrochemical window of 1.5 V demonstrates high specific energy density of ~31 Wh kg-1. Of significance, we strongly envision that hollow design concept and new findings here hold great promise for enriching synthetic chemistry and electrochemistry of complex metal sulfides for next-generation ECs.
Effect of Morphology on the Electrochemical Properties of Lithium Titanate Anode Materials
Authors: Li Jianling 
Published: February 2020

Effect of morphology on the electrochemical properties of lithium titanate anode materials
Zhanyu Lia, Jianling Lia*, Yuguang Zhaoa, Kai Yangb, Fei Gaob

a State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, No. 30 College Road, Beijing 100083, China

b China electric power research institute, Beijing 100085, P. R. China)
* Corresponding author. Tel/ Fax: +86 10 6233 2651
Email Address: lijianling@ustb.edu.cn(J.Li)
In recent years, Lithiumion batteries (LIBs) are popular electrochemical devices. In case of the anode, carbonaceous materials have been used as the most common commercial anode materials for LIBs. However, carbonaceous materials as anode material have a lot of problems in the safety and life. Therefore, there is an urgency to develop the LIBs with high power density, good cyclic stability and low cost. Recently, Li4Ti5O12 (LTO) has attracted much interest due to its potential application as an anode material for high-power LIBs.[1-3]
In this work, two different morphologies of lithium titanate were synthesized by solid-state method and liquid phase method (as shown in Fig.1). It can be seen from Fig. 1 that the SEM image of LTO was synthesized liquid phase method (Fig.1b) shows uniform spheres morphology distributed, but LTO was synthesized solid-state method (Fig.1a) shows a little agglomeration. Fig.2 shows the rate capacity of LTO samples at different rates of 0.2 C, 0.5 C, 1 C, 2 C, 5 C and 10 C. It can be seen that the rate capacity of LTO obtained by liquid phase method is better than that of LTO synthesized by solid-state method. It may be attributed to the deagglomeration and uniform LTO crystallites that were generated by liquid phase method. Therefore, different morphologies have great influence on the electrochemical performance of LTO.
Fig.1. SEM image of Li4Ti5O12were synthesized by solid-state method (a) and liquid phase method (b)
Fig.2. Rate performances of LTO samples
Reference

Dunn B, Kamath H, Tarascon JM (2011) Electrical energy storage for the grid: a battery of choices. Science, 334: 928-935

Ying Y, Hao WY, Lai QY, Lu JZ, Chen YD, Ji XY (2008) A new composite material Li4Ti5O12-SnO2 for lithium-ion batteries. Ionics, 14:85-88

Zhou TP, Feng XY, Guo X, Wu WW, Cheng S, Xiang HF (2015) Solid-state synthesis and electrochemical performance of Ce-doped Li4Ti5O12 anode materials for lithium-ion batteries. Electrochim Acta, 174:369-374

Acknowledgments
The work was financially by the science and technology project of State Grid Corporation of china (DG71-15-042).

Figure 1
Silver Modified MnO2 As an Electro-Catalyst for Oxygen Reduction Reaction in Alkaline Fuel-Cell and Battery Applications
Authors: Velraj Samgopiraj , Beverage Kevin , Wang Yuxuan , Li Zhe-Fei , Botte Gerardine G 
Published: February 2020

The commercial viability of alkaline fuel cells and metal-air batteries as future energy applications hinges to a large extent on the development of highly efficient catalysts for the oxygen reduction reaction (ORR). Currently, platinum nanoparticles are the de facto cathode electrode materials to catalyze the sluggish ORR [1]. However, the scarcity of Pt metal coupled with their ever-growing demand are key obstacles for the broad deployment of this precious metal in all commercial technologies [2]. The logical solution to this persistent problem is an alternate catalyst with good ORR capabilities and durability at a reduced cost.
Several metals, metal-oxides, and non-metal based catalyst are being studied as alternate ORR catalysts with limited success [3]. Among metal-oxides, manganese oxide (MnO2) has gathered enormous interest due to their ability to catalyze the disproportionation reaction of HO2
- to H2O and catalyze 4-electron reduction of oxygen in combination with another material (usually carbon) active for 2-electron reduction of oxygen to peroxide [4]. Another method to improve ORR capabilities is to incorporate a small amount of noble metals in to the metal-oxide catalyst structure. It is expected that modifying catalysts with an inexpensive noble-metal such as silver would result in an improvement in the electrochemical performance of the cathode without significantly increasing catalyst cost. Additionally, the high activity of silver for oxygen reduction [5] and their superior electrical conductivity probably have additional synergy effect on the catalysts as shown for other bi-functional catalyst [6].
The objectives of this study are as follows: (i) synthesis and evaluation of MnO2 nanoparticles structure/morphology with and without silver, (ii) characterization of the synthesized catalyst materials using RDE to determine the effect of silver addition on the ORR kinetics, and, (iii) long-term durability testing of the cathodes prepared with different catalysts at higher current density to ensure their feasibility as ORR cathodes in alkaline media.
Fig. 1. shows the TEM and XRD of the MnO2 catalyst synthesized using the hydrothermal method. The XRD peaks of the catalyst powder as shown in Fig. 1a were identified as MnO2, while the TEM image shows a flake-like structure. Long-term durability testing of the MnO2-based cathode was performed using the three electrode cell design.
Fig. 2 shows the voltage measured at the cathode maintained at a constant current density of -150 mA.cm-2in 6 M KOH. Clearly, no noticeable drop in voltage was observed for 200 hr indicating good stability of the cathode for ORR over extended periods.
-

Figure 1
A Versatile Measuring Setup for the Electrochemical Characterization of Materials Developed for Energy Storage Devices
Authors: Vyas Ritesh , Kubicsko Michael , Huber Benedikt , Drüschler Marcel 
Published: February 2020

Recent development in the fields of energy storage and energy conversion has rapidly gained a fascinating momentum. A central aspect is the search for methods to enhance the safety, efficiency and durability of energy storage devices like lithium ion batteries. Particularly, the performance of the different components of such devices, like the electrodes, the electrolyte and the separator, as well as the interplay among them, has to be improved. Thus to characterize the properties of modified and novel materials, there is a need not only for measuring devices but also for measuring setups.
The Microcell HC setup offers different types of measuring cells which are suitable for the electrochemical characterization of liquids, gels, and polymers with a low to high viscosity as well as the characterization of solid samples [1]. Depending on the measuring cell, the measurements can be performed in both a two- and three-electrode setup. During measurements the temperature of the sample can be controlled quickly and precisely. Only a small sample volume (milligram range) is required, which allows for electrochemical analyses of substances that are only available in small amounts and/or extremely expensive.
Already established applications of the setup are the measurement of the conductivity of ionic liquids, polyelectrolytes [2], and polymer electrolytes, electrochemical impedance spectroscopy for the characterization of the interface ionic liquid/electrode [3], and cyclic voltammetry for a large variety of electrochemical systems [4]. Especially cyclic voltammetry experiments, but also measurements utilizing a three-electrode setup, require a reference electrode. For electrochemical measurements on ionic liquids or carbonate based electrolytes, a microreference electrode can be used [5].
Literature:
[1] B. Huber, M. Drüschler, B. Roling, Nachrichten aus der Chemie
2012, 60, 1213- 1214. [2] B. Huber, L. Rossrucker, J. Sundermeyer, B. Roling, Solid State Ionics
2013, 247-248, 15-21. [3] J. Wallauer, M. Drüschler, B. Huber, B. Roling, Z. Naturforsch.
2013, 68b, 1143-1153. [4] J. Schwaben, N. Münster, T. Breuer, M. Klues, K. Harms, G. Witte, U. Koert, Eur. J. Org. Chem.
2013, 2013, 1639-1643. [5] B. Huber, B. Roling, Electrochim. Acta
2011, 56, 6569-6572.
Aqueous Ion Intercalation in Hydrous Oxides
Authors: Lo William , Wang Ruocun , Augustyn Veronica 
Published: February 2020

Transition metal oxides are often the materials of choice for energy storage and conversion applications due to their numerous oxidation states, mixed electronic/ionic conductivity, and structural variability. Here, we describe the electrochemical behavior of hydrous hexavalent tungsten and molybdenum oxides (WO3 and MoO3, respectively) as model material systems for investigating aqueous intercalation mechanisms. These oxides offer the benefits of multi-valent transition metal redox, diversity of crystal structure, hydrated polymorphs, and a variety of synthesis techniques that yield bulk powders, nanomaterials, and nanosheets. The mechanism of ion intercalation is dependent upon two different regions of the material: the internal structure, or the solid-state environment that controls the ion diffusion and favorable storage sites, and the external surface, or the nature of the electrochemical interface which controls the charge-transfer step of the intercalation reaction as well as stability. We characterize the behavior of these oxides in a variety of aqueous electrolytes in order to understand the effect of electrolyte ion size, charge, and hydration on the intercalation mechanism. We find that the presence of structural water and the nature of the intercalating ion both result in significant effects on the aqueous intercalation mechanism in tungsten and molybdenum oxides.
Transparent and Flexible Energy Storage Using Pseudocapacitive Ni(OH)2 coated Cu Nanowires By Solution-Processes
Authors: Thostenson James O. , Cordova Isvar A. , Stewart Ian E. , Amsden Jason J. , Parker Charles B. , Liu Jie , Wiley Benjamin J. , Glass Jeffrey T. 
Published: February 2020

Realization of cost-effective energy storage that is both safe and scalable relies on the ease with which it can be integrated into existing manufacturing technology. Roll-to-roll and solution-based processes are two such technologies that offer the ability to deposit flexible films of controlled thickness for a low cost device. Our work uses one such approach to build a transparent and flexible pseudocapacitive electrode using earth-abundant and low cost materials. The electrode is comprised of a core/shell Cu/Ni(OH)2 structure of nanowires (NWs) on a glass slide. In order to understand the effects of both NW network density and the thickness of the Ni(OH)2 shell, we utilize Meyer rod and electroless plating techniques to control the network density and shell thickness, respectively. Our study uses NW networks with resistance of <50 Ω/sq. and >60% transmittance to investigate the performance of Ni(OH)2shells with 20, 30, and 40 mol% Ni, with respect to the conductive Cu core.
Controlling the Cu NW density and Ni(OH)2 shell thickness yields capacitances of 800 F/g and 2550 μF/cm2 at 0.02 mA/cm2 charge-discharge current density with >70% transmittance. The 30 mol% Ni on Cu NW structure exhibits higher gravimetric capacitances than the 20 and 40 mol% Ni structures. We propose that these differences are due to diffusion limitations limiting the amount of electrochemically active material and to the density of active NWs, which impacts the sheet resistance of the underlying conductive NW network. In addition, the quasi-1D Ni(OH)2 structure of our NW devices enabled highly reversible pseudocapacitive intercalation and remarkably stable performance under fast charge-discharge rates, exhibiting coulombic efficiencies of >90% with only a 13% decrease in capacitance after 10,000 cycles for the thicker 40 mol% Ni(OH)2 shell.
Our continuing and future work in exploring the Cu/Ni(OH)2 NW material is to further stabilize and improve both areal and gravimetric capacitance while we investigate the use of a flexible polypropylene (PPE) substrate. Preliminary results show that the electrode can be bent at a 90° angle and retain capacitive behavior beyond 12 hrs in solution. Additionally, we seek to match our electrode’s characteristics with a suitable counter electrode and solid-state electrolyte to construct a fully flexible, hybrid supercapacitor device.

Figure 1