bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling of Methanol-Fueled SOFC with Anode Offgas Recycling for Simplified System Design
Authors: Larose Sylvain , Labrecque Raynald , Mangin Patrice J.
Published: February 2020

Objective :

Methanol is a fuel that can be synthesized from either fossil fuel or biomass. Use of methanol as a fuel in SOFCs offers several advantages. A major advantage lies in its ease of storage, handling, distribution, and input, being found in liquid form under ambient conditions. Compared to most other fuels, methanol is rather easily produced, and is known to have a lesser tendency for carbon deposition when vaporized and heated at high temperature.

In this work, we conducted modeling and simulations of a methanol-fed SOFC system with anode gas recycling. Anode gas recycling provides water vapor in the fuel inlet, thus decreasing the tendency of the feed gas to form carbon deposits in the fuel cell stacks. This strategy also helps reduce thermal stresses in the stacks that would arise if the reforming was attempted in-situ with 100% water vapor originating from outside the SOFC system. The recycling also helps increase the fuel utilization. A thermodynamic analysis was conducted to calculate the energy generated, absorbed, or exchanged in the various blocks of the system, the expected system energy output, as well as conditions under which carbon deposition is prevented.

Results:

The model is based on an integrated energy process with anode gas recycling, a rated output electrical power of 100 kW, and an electrical efficiency of 50% to initiate simulations. Using the CHEMCAD software, equilibrium gaseous compositions were calculated. The oxygen flow rate and the cell temperature were set at five times the stoichiometric value and 800°C, respectively.

Thermodynamic calculations show that the gas mixture at the anode inlet will not lead to carbon deposition above 575°C. The energy generated in the cell by electrooxidation is calculated at 144.6 kW. 44.6 kW of thermal energy is thus generated at the stack level. This heat is removed by the anode and cathode outlet flows, as well as minor heat losses through the system walls. A mass recycle ratio of 1.47 was obtained. Energy involved in each of 9 system blocks was calculated. Overall system and electrical efficiencies of 75% and 57% were obtained from simulations based on lower heating value. A voltage ranging from 0.91 to 0.94 V across the cell stacks was obtained at a fuel utilization factor of 80% and a temperature of 800°C. Finally, simulation iterations lead to an output fuel cell power of 98.8 kW, which is close to the power value used as input at the start of simulations.

Conclusion:

The recycle ratio of 1.47 contributes to system efficiency. By contrast, it was reported that for propane, a fuel utilized in Northern Canada, a recycle ratio greater than 5 is required for reliable functioning of SOFC systems. Modeling and simulation results clearly showed that methanol has very little tendency to form carbon deposits during cracking in situ when used in a simple anode gas recycling system. A very good electrical efficiency is thus obtained.
In Situ Optical Investigations of Contaminants in Operating Solid Oxide Fuel Cells
Authors: Kirtley John D , Tsoi Stanislas , Qadri Syed Noorullah , Steinhurst Daniel A , Reeping Kyle W. , Walker Robert A , Owrutsky Jeffrey C.
Published: February 2020

Solid oxide fuel cells (SOFCs) can generate electricity efficiently and with broad fuel flexibility, but practical applications require them to be more durable and resistant to degradation when subjected to impurities. In order to better understand poisoning mechanisms and guide strategies for developing more durable materials and devices, we have used operando optical methods combined with electrochemical measurements and exhaust gas analysis to investigate the effects of chlorine and sulfur on Ni/YSZ anodes in high temperature (700 °C) SOFCs. The effects of chlorine contamination were found to be more severe for methane than hydrogen operation based on studies of anode-supported Ni/YSZ SOFCs with 100-300 ppm CH3Cl. Reduced anode activity was indicated by suppressed carbon formation from Raman measurements and fewer oxidation products from infrared emission results. Evidence regarding the degradation mechanism is provided by the differences in recovery for hydrogen and methane. The anode activity is also reduced for operation on methane in the presence of 170 ppm H2S during both electrochemical and stream removal of carbon. Changes in endothermic methane cracking reactions at the anode are monitored with near infrared thermal imaging while gas and surface species are observed with infrared emission spectroscopy, thereby providing some of the first operando studies of sulfur effects on SOFC anodes.
Chromate-Based Oxide Anodes for Low-Temperature Operating Solid Oxide Fuel Cells
Authors: Abdul Jabbar Mohammed Hussain , Robinson Ian , Pan Ke-Ji , Blackburn Bryan M. , Pellegrinelli Christopher , Huang Yi-Lin , Wachsman Eric D.
Published: February 2020

Doped-YCrO3 ceramic oxides were investigated as potential anode materials for low-temperature solid oxide fuel cells (LT-SOFC, 400-650°C). This material has shown orthorhombic symmetry with the space group pmmm. Electrical conductivity >1 S/cm at 650°C was measured under reducing gas conditions. The anode-supported SOFCs were prepared by laminating GDC and doped-YCrO3 tapes. A fired half-cell assembly was further deposited with a dense barrier layer made of electrolyte material. The function of the barrier layer at the interface of GDC electrolyte and anode was to prevent the interdiffusion of elements. Furthermore, the LSM/bismuth-based composite low-temperature cathode was deposited on the barrier layer and Ni-GDC precursor was infiltrated on the anode (to introduce catalytic activity for hydrogen oxidation). Peak power density of 700 mW/cm2 (at 2 A/cm2) was obtained at 650°C in H2/3% H2O.
Gallium Doped Sr(CoFe)O3 Perovskite as the Stable Electrodes of the Flexible SOFC and SOEC for Both Power Generation and Hydrogen Production
Authors: Xie Menghan , Meng Xiuxia , Yang Naitao , Shen Yichi , Meng Bo , Liu Shaomin , Tan Xiaoyao
Published: February 2020

Cobalt and ion based perovskite such as Sr(CoFe)O3, Ba0.5Sr0.5Co0.8Fe0.2O3-
δ and La0.6Sr0.4Co0.2Fe0.8O3-
δare considered as promising cathodes of SOFC or anodes of SOEC. However, cobalt and iron oxides are easily reacted with the gases such as H2, CH4, CO2and water steam at high temperature, causing the perovskite structure to be easily decomposed. To stabilize the perovskite structure of the electrodes is a serious challenge for the fabrication of the long-life SOFC or SOEC.

In this work, gallium is used as a dopant to stabilize Sr(CoFe)O3, developing a SrCo0.8Fe0.1Ga0.1O3-δ(SCFG) perovskite material to work as the electrodes of flexible SOFC and SOEC with a microtubular structure.

SCFG show a high oxygen reducing performance when it is prepared into oxygen separation membrane, Obtaining an oxygen flux of 3~6 mL·min-1·cm-2 at the temperature of 800~950°C. Even under pure CO2, pure CH4 and H2(4vol%), SCFG membrane still works steadily for as long as 200 h with no decreasing.

A microtubular solid oxide cell in the configuration of Ni-YSZ|YSZ|GDC|SCFG is fabricated and tested in SOFC or SOEC modes from 550 to 850°C, using hydrogen as the fuel or as the product, respectively. Under SOFC mode, a maximum power density of 1044 mW cm-2 is obtained at 750°C. In the electrolysis mode, when the applied voltage is controlled at 2V, the electrolysis current density reaches 3.33A cm-2 at 850°C with the hydrogen production rate up to 22.9 mL min-1 cm-2
(STP). These results reveal that SCFG is a very promising oxygen electrode material for the application in both SOFC and SOEC.
Minimizing the Influence of Experimental Uncertainty for Delivered Methane/Steam Reforming Kinetic Equation by the Optimized Design of Experimentation
Authors: Sciazko Anna , Komatsu Yosuke , Brus Grzegorz Adam , Shikazono Naoki , Kimijima Shiniji , Szmyd Janusz S.
Published: February 2020

One of the important issues in the future development of Solid Oxide Fuel Cells (SOFC) is increasing the fuel flexibility of the commercially available units. In order to provide the accurate models for SOFC coupled with internal indirect reformer or with direct internal reforming reactions, it is necessary to provide the reliable description of the reaction kinetic of fuel reforming process. This research focuses on the methane/steam reforming process and method to develop effective experimental-calculation procedure to deliver the reliable kinetic reaction rate expression.

The experimental studies were conducted on the NiO:YSZ (60:40vol%) catalyst, one of the most typical materials, for Solid Oxide Fuel Cell anodes. The experimental conditions included various temperatures, methane flow, steam-to-carbon ratios and nitrogen-to-carbon ratios, which defines each of the measurement points. The goal of this study was to decrease the number of necessary experimental measurements for the calculations of the empirical parameters defining the kinetic of methane/steam reforming reaction. By the analysis with the Orthogonal Least Squares Method and an analysis of a-posteriori covariance matrix, the experimentation process has been optimized. The proposed systematic approach was applied to evaluate the minimal number of measurements required to achieve the assumed accuracy of final solution and to reveal the influence of distribution of experimental condition for the quality of final reaction kinetic equation.

It was proved that the number of experimental measurements can be reduced without significant deterioration in the quality of solution, if the dismissed measurements are properly chosen. In the paper the correlation between design experimental condition and quality of delivered model for the methane/steam reforming reaction is discussed. The proposed deliberation can be extended and provide useful strategy for the design of experimental procedures for the estimation of empirical reaction kinetic for various catalytic materials.
Electrochemical Properties of YSZ/GDC Bi-Layer Produced by One-Side Dip Coating Method for the Intermediate Temperature Solid Oxide Fuel Cell
Authors: Kim Sungmin , Jang Inyoung , Kim Chanho , Yoon Heesung , Paik Ungyu
Published: February 2020

The Gadolinium Doped Ceria (GDC) diffusion barrier layer was formed on the Yttrium Stabilized Zirconia (YSZ) electrolyte to apply La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) cathode system for lowering the operating temperature of Solid Oxide Fuel Cell. In this study, YSZ and GDC layers were coated by one-side dip coating method which possibly coat one-side of anode substrate. Cu(NO3)2 was infiltrated into pre-sintered substrate of anode and electrolyte as a sintering aid for lowering the co-firing temperature which was enough to produce dense electrolyte layer. LSCF-GDC cathode was coated on the GDC layer by screen printing method. The cells were operated at 600℃ and 650℃. The microstructures of the surface and cross-section were observed by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). The ohmic and polarization resistance were measured by the Electrochemical Impedance Spectroscopy (EIS).
Evaluation of Electrochemical Properties of La0.6Sr0.4Co0.2Fe0.8O3-δ Porous Electrode with Sulfur Poisoning
Authors: Budiman Riyan Achmad , Ishiyama Tomohiro , Bagarinao Katherine Develos- , Kishimoto Haruo , Yamaji Katsuhiko , Horita Teruhisa , Yokokawa Harumi
Published: February 2020

Among several issues in the degradation of the cathode performance of solid oxide fuel cells (SOFC), sulfur poisoning is one of the most studied so far. Several experiments on the cell performance have been performed to understand the poisoning mechanism on SOFC cathodes. In this study, the performance of La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) porous cathode on Ce0.9Gd0.1O1.95 (GDC) electrolyte was evaluated at 0.01 ppm SO2 gas. The evaluation was carried out at various temperatures as function of temperature and poisoning time under -0.3 A of dc bias. The 0.01 ppm SO2 gas was feed into the measurement chamber after stable condition was achieved during I-V test. A large degradation was observed at low operation temperature (823 K). In contrast at high operation temperature (1023 K) degradation was hardly observed. These results are in good agreement with the evaluation of the surface oxygen exchange coefficient, k*, by Adler – Lane – Steele model. The k* which was determined for the sample operated at low operation temperature showed larger degradation over poisoning time compared to that at high temperature. This indicates that the surface of LSCF was largely affected by sulfur poisoning. The evaluation of poisoning mechanism and compositional change of LSCF cathode during sulfur poisoning will be discussed in this presentation.
Effect of Deposition Temperature on the Microstructure and Performance of Vacuum Cold Sprayed Nano-Structured LSCF Cathodes for Solid Oxide Fuel Cells
Authors: Zhang Shan-Lin , Shang Yuan-Bo , Li Cheng-Xin , Li Chang-Jiu
Published: February 2020

Here, we investigate the feasibility of using vacuum cold spray process as a novel method for the cost effective fabrication of a nano-structured La0.4Sr0.6Co0.2Fe0.8O3 (LSCF) as a high-performance cathode for low-temperature solid oxide fuel cells (LT-SOFCs). Nano sized LSCF particles were used as feedstock. The effects of deposition temperature and particle size on the phase composition, microstructure, and electrochemical performance of the resulting cathodes were studied. The results indicate that 10~20 μm nano-structured porous LSCF cathodes can be successfully prepared by vacuum cold spray process. However, the deposition temperature shows significant influence on the microstructure. When the cathode was deposited at room temperature, there were many unbonded interfaces between the cathode and electrolyte. With the increase of deposition temperature, the interface bonding was improved. At a deposition temperature of 300 °C, it can be found that the cathode and electrolyte were bonded well. Besides, the results indicate that the cathode polarization resistance decreased significantly with the decrease of spray particle size. When particle size decreased from 150 nm to 50 nm, the cathode polarization resistance decreased from 11 Ωcm2 to 1.5 Ωcm 2 at 450 °C. Our results suggest that vacuum cold spray has potential to be a low-cost and flexible process suitable for the fabrication of nano-structured cathodes for LT-SOFCs.
Preparation, Characterization and Oxygen Storage Capacity Analysis of La1-XSrXAlO3 Perovskite Materials as Promising Anode for SOFC
Authors: Dasari Harshini , Yaranal Naveen kumar , Neelapala Satya Deepika
Published: February 2020

The Perovskite materials of structure ABO3 are of great interest because their properties can easily be tailored by partial substitution at the A-site, the B-site, or at both A- and B-sites [1]. The partial substitutions at A- and B-sites create structural defects such as oxygen vacancies, which greatly affect properties like electrical conductivity and thermal stability under oxidizing and reducing conditions [2,3,4]. Recent studies have shown that perovskite-like oxides can serve as possible replacements for Ni-based anode materials [5,6], primarily due to their reported coking resistance which is attributed to their high oxygen storage capacity.

To develop efficient materials possessing high oxygen storage capacity (OSC) for a number of catalytic applications, and also as anodes for SOFC, A series of Strontium doped LaAlO3 perovskites with formula La1-XSrXAlO3
−
δ (x=0–0.10) were prepared by precipitation of nitrate precursors followed by calcination at 800 °C in air for 24h. The material properties of the substituted perovskites were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) analyses, Raman Spectroscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The doped materials exhibited a single perovskite phase in air up to the Sr doping of 0.4 mole % which was revealed from XRD and Raman analysis. The redoxability and size of the dopants were proposed to play a pivotal role in enhancing the OSC of the as-prepared materials. In this context, the oxidation state of a dopant located at the surface was determined by XPS, Soot oxidation experiments were further performed to examine the relative OSC of the La1-XSrXAlO3
−
δ based solid solutions and revealed that soot oxidation activities increased till the Sr doping of .05 mole% when compared to undoped LaAlO3. These results clearly shows that La1-XSrXAlO3
−
δ materials can be used as anode for SOFC.

References

M.A. Pena, J.L.G. Fierro, Chem. Rev. 101 (2001) 1981.

Y. Itagaki, M. Mori, Y. Hosoya, H. Aono, Y. Sadaoka, Sens. Actuators, B 122 (2007) 315.

Q.T. Wei, R.S. Guo, F.H. Wang, H.L. Li, J. Mater. Sci. 40 (2005) 1317.

H. Ulmann, N. Trofimenko, F. Tietz, D. Stover, A. Ahmad-Khanlou, Solid State Ion. 138 (2000) 79.

S.P. Jiang, X.J. Chen, S.H. Chan, J.T. Kwok, J. Electrochem. Soc. 153 (2006) A580.

S. Tao, J.T.S. Irvine, Chem. Rec. 4 (2004) 83.
Microtubular SOFC (mSOFC) System in Mobile Robot Applications
Authors: Kendall Kevin , Liang B , Kendall Michaela
Published: February 2020

The weak link in mobile robots at present is the battery. A typical robotic device for consumer applications contains a 1kWh battery which runs down with time. Also, the battery requires swapping or lengthy recharging after each shift. The purpose of this paper is to discuss battery extension by adding an mSOFC generator running on propane. This keeps the battery at a high voltage, removing deep discharge problems, while giving a factor 10 longer running time with rapid turnaround because the on-board propane tank can be swapped in 1 minute. An international research project was initiated in 2016 to develop these ideas under the heading PERT (PODS: Extending Robot Traction). This paper describes results from the first 12 months of the project and shows that mSOFCs operating on small mobile robots can give substantial benefits in several applications. The alternative is to stack several batteries on the robot. This paper shows that extra battery weight increases the energy expenditure in a predictable way, demonstrating that the battery hybridised with lightweight fuel cell plus fuel is beneficial.
NMR Transport Study of LiPF6 and NaPF6 in Glymes for Use in Supercapacitors
Authors: Morales Daniel Jaime , Gobet Mallory , Greenbaum Steven , Ruther Rose E. , Nanda Jagjit
Published: February 2020

Electric double-layer capacitors (EDLC) store ionic charge electrostatically at the interface of high surface area electrodes such as carbon in a liquid electrolyte. Despite significant improvements in electrode and materials design, virtually all state-of-the-art nonaqueous electrochemical capacitors use the same electrolyte: tetraethylammonium tetrafluoroborate (TEABF4) in acetonitrile (ACN). This electrolyte has an exceptionally high conductivity which minimizes resistive losses and enables capacitors to operate at very high power. However, this electrolyte has a practical voltage window around only 2.7 V, beyond which the capacitor lifetime is significantly shortened. Since the energy stored in a capacitor increases quadratically with voltage, extending this electrochemical window could significantly improve the energy density. In this study we report on electrolytes consisting of LiPF6 or NaPF6 in tetraethylene glycol dimethyl ether (TEGDME or tetraglyme or G4), bis(2-methoxyethyl) ether (diglyme, or G2) and dimethoxyethane (DME or G1) which clearly show a 4 V electrochemical window. The extended voltage window doubles the energy density that can be achieved with any given capacitor electrode. Electrolyte conductivities range from 1-10 mS/cm, which are comparable to ionic liquids and adequate for moderate power applications. Futhermore, glyme-based electrolytes have good chemical stability and low flammability. Importantly, all salts and solvents are commercially available, which should enable these electrolytes to be as cost-effective and scalable as the current generation of commercial supercapacitor electrolytes.

NMR experiments were performed on 0.1m LiPF6 and 0.1m/0.8m NaPF6, each dissolved in G1, G2, and G4. Using Pulsed Field Gradient (PFG) NMR, the solvent and ionic self-diffusion coefficients, D, of 1H, 7Li, 19F, and 23Na were measured, at both 25°C and 60°C. As NMR does not distinguish between the movement of single ions and ion pairs, it can be difficult to accurately determine the true conductivity of the material. However, the diffusion measurements were used to find the limiting conductivity, σNMR
, of each material via the Nernst-Einstein equation:

σNMR = F2[C]/(RT)*(Dcation+Danion)

Direct comparison with conductivity values obtained by electrochemical impedance spectroscopy measurements yields the degree of ion association, α:

α = 1 - (σdirect/σNMR)

Both diffusion and conductivity decrease with increasing solvent size, primarily attributed to viscosity effects. However the degree of ion association is significant, determined to be 85% for both 0.1m LiPF6 and 0.1m NaPF6 in G2. In glyme solvents, ion association tends to decrease with increasing solvent molecular mass, and increase with increasing temperature. These results will be discussed in the context of practical use of glyme-based electrolytes for electrochemical capacitors.
In Operando Cell Diagnostics with MRI
Authors: Mohammadi Mohaddese , Ilott Andrew , Silletta Emilia , Ganter Matthew J. , Schauerman Christopher , Jerschow Alexej
Published: February 2020

We are presenting battery assessment technology based on non-destructive Magnetic Resonance Imaging (MRI) techniques. The approach works on rechargeable batteries (for example, Li-ion batteries), even when the cells are encased in conductive material. For example, even commercial-type cell-phone batteries can be analyzed with this method. The technique is based on the measurement of magnetic susceptibility changes within cells, as well as, the measurement of current distributions. With this technique, hence, it is possible to diagnose the state of charge (SOC) and state of health (SOH) of cells. The measurement is fast (a couple of seconds), and could be adapted to a range of cell types. We demonstrate the technique with a selection of cell types, defects, cell chemistries, and form factors. The Figure shows the a schematic of the setup and examples of images of different cells which are used to diagnose the SOC/SOH. The technique represents a new opportunity for nondestructive cell diagnostics, and hence could be of great help in the development of next-generation batteries. We demonstrate the identification of defects, state of charge, and classification of cells based on different types of features.

Figure 1
Role of Transition Metal Identity in Suppression of Interlayer Migration in Layered Cathode Materials
Authors: Vinckeviciute Julija , Radin Maxwell , Van der Ven Anton
Published: February 2020

As Li-ion batteries continue to dominate in the portable electronics and electric car industries we look to increase capacity by cycling the batteries at higher voltages. Alloying transition metals and dopants to cathode materials can aid in pushing the voltage limit beyond current capabilities. However, at higher voltages, problems like interlayer dopant migration become a serious detriment that result in phase transformations and material break down. Using first-principles methods, we have unraveled the electronic structure that depresses interlayer atom migration. Surprisingly, this electronic structure is largely a contribution of the local environment around the dopant and not simply a function of the dopant’s identity. Using this understanding, we propose design principles for managing interlayer atom migration in cathode materials, with specific implications for NCA, NMC, and Li-excess cathodes.

Figure 1
Electrochemical Thermoelectric Coefficient of Prussian Blue Analogues
Authors: Fukuzumi Yuya , Kobayashi Wataru , Niwa Hideharu , Moritomo Yutaka
Published: February 2020

The electrochemical thermoelectric coefficient (S
EC = dV/dT, where V and T are the redox potential and temperature, respectively) is a significant material parameter, which enables thermal power generation with use of thermocell during heat cycles. Recently, the thermal power generation has been demonstrated using two kinds of Prussian blue analogues (PBAs) with different S
EC
[1]. To realize the thermocell with high efficiency, the S
EC values are systematically investigated for three PBAs, Na
x
Co[Fe(CN)6]0.71 (NCF71), Na
x
Co[Fe(CN)6]0.90 (NCF90), and Na
x
Mn[Fe(CN)6]0.83 (NMF83) against sodium concentration (x).

The figure shows the discharge curve (the black solid line) and S
EC against x (the orange closed circles) of NCF90. The discharge curve shows two plateaus regions (plateaus II and III) around 3.8 and 3.2 V. Plateau II is ascribed to the reaction [2]: Co3+[Fe3+(CN)6]0.6[Fe2+(CN)6]0.3+ 0.6Na+ → Na0.6Co3+[Fe2+(CN)6]0.9. Plateau III is ascribed to the reaction[2]: Na0.6Co3+[Fe2+(CN)6]0.9 + Na+ → Na1.6Co2+[Fe2+(CN)6]0.9. Thus the plateau II (the plateau III) on the discharge curve means reduction process of Fe3+ (Co3+)[2]. On the other hand, S
EC distributes around 0.4 mV K-1 (1.4 mV K-1) in the plateau II (the plateau III). Therefore, it is suggested that S
EC significantly depend on the redox site. In the presentation, we also report S
EC of NCF71 and NMF83 and discuss the material and redox site dependences of S
EC by using ionic model (point charge model) approach.

[1] T. Shibata, Y. Fukuzumi, W. Kobayashi, Y. Moritomo, submitted.

[2] R. L. Magnússon, W. Kobayashi, M. Takachi Y. Moritomo, AIP adv. 7 045002 (2017).

Figure 1
Yolk-Shell Structured Sb@C Anodes for High Energy Na-Ion Batteries
Authors: Song Junhua , Yan Pengfei , Luo Langli , Wang Chongmin , Lin Yuehe , Li Xiaolin
Published: February 2020

Na-ion batteries (NIBs), as the analogy to Li-ion batteries, are regarded as one of the most promising technologies to satisfy the request on both performance and cost for grid energy storage. To further boost the specific energy and power of the state-of-the-art NIB, an anode material with comparable capacity and long-term stability to graphite anodes in lithium-ion batteries (LIBs) is highly desired. Antimony (Sb) has a theoretical capacity of 660 mAh g−1 upon full sodiation and hence holds great promises as the good anode candidate for high energy Na-ion batteries.

A low cost and scalable approach of annealing poly-dopamine (PDA) coated Sb2O3 was used to prepare the yolk-shell structured Sb@C nanocomposite for high performance Na-ion battery anodes. Controlled reduction reaction and selective removal of Sb2O3 by acid etching generate the promised void space to accommodate the volume expansion of Sb while carbonization of the PDA forms highly conductive carbon shells. The by-product from the etching, SbCl3, can be reused rendering the approach a scalable and economic one. The yolk-shell Sb@C anode exhibits excellent electrochemical performance in terms of specific capacity, rate capability and cycling stability. The reversible phase transformation of crystalline Sb during charge/discharge was observed by the in-situ XRD for the first time. The designed composite with Sb: C of 70: 30 delivers almost theoretical capacity of ~ 554 mAh g−1. The specific capacity is still ~ 315 mhA g−1 at the current density of 5 A g−1 (10 C rate). The O3-Na0.9[Cu0.22Fe0.30Mn0.48]O2 (cathode)-Sb@C-hard carbon (anode) full-cell shows high specific energy of ~ 130 Wh kg−1 (based on the total weight of cathode and anode) in the voltage range of 2.0–4.0 V in NaClO4 electrolyte with 10 wt% fluoroethylene carbonate (FEC) additive. It is ~ 1.5 times energy of the full-cells with similar design using hard carbon anodes (~ 84 Wh kg−1).

Figure 1
Cycling Performance of Sodium Ion Battery Comprised of Naphthalene Based Polyimide/MWCNT Composite Cathode and Highly Porous Polyvinylidene Fluoride Separator Membrane
Authors: Manuel James , Ramasamy Ramaraja P.
Published: February 2020

Large scale energy storage is the key to incorporating renewable resources like wind, tidal, and solar into power grid allowing us to use these resources when power is needed. High cost and less availability of lithium metal hampers the usage of the present reigning energy storage champion-lithium ion batteries (LIBs) in large scale applications. Sodium ion batteries (NIBs) could provide an alternative solution for expensive LIBs because sodium is the 4th most abundant metal on earth and has worldwide availability. The energy density is not crucial issue in the field of large scale energy storage systems and therefore low cost of NIBs surpasses the lower gravimetric and volumetric densities of NIBs than LIBs1. Currently electrochemists are involved in the hunting for highly efficient electrode materials for NIBs. Advantages like stability, insolubility in electrolytes, and a high theoretical capacity with its two available anhydride groups attached to the stable aromatic ring makes the polyimide (PI) as a preeminent candidate for cathode active material for NIBs2.

In this work we have synthesized naphthalene tetracarboxylic dianhydride (NTCDA) based polyimide/multi-walled carbon nanotube (PI/MWCNT) composite for use as a cathode active material for high performance NIB. PI/MWCNT composite was synthesized in a two-step process and was characterized using field emission scanning electron microscopy (FE-SEM) and Fourier Transform infrared spectroscopy (FTIR). Three-dimensional network of MWCNT inside and between PI particles enhances the conductivity and thereby electrochemical performance of PI/MWCNT composite electrode. A highly porous polyvinylidene fluoride (PVdF) membrane made by phase inversion method was used as the separator for NIB. The electrochemical performance of cells based on PI/MWCNT composite cathode with PVdF membrane delivered high capacity and cycle capability at different C-rates.

Fig. 1: SEM image of cross section of PVdF membrane.

References:

1. Ong, S. P.; Chevrier, V. L.; Hautier, G.; Jain, A.; Moore, C.; Kim, S.; Ma, X.; Ceder, G., Voltage, stability and diffusion barrier differences between sodium-ion and lithiuim-ion intercalation materials. Energy & Environmental Science
201
1, 4, 3680-3688.

2. Mazur, S.; Lugg, P. S.; Yarnitzky, C., Electrochemistry of aromatic polyimides. Journal of Electrochemistry (1987), 134, 346-353.

Figure 1
Theoretical Understanding and Experimental Suppression of the Capacity Degradation of Ni-Rich Layered Oxide Cathode Materials for Li Ion Battery
Authors: Kong Fantai , Liang Chaoping , Longo Roberto C , Zheng Yongping , Wheeler Virginia D. , Wollmershauser James , Feigelson Boris , Cho Kyeongjae
Published: February 2020

Ni-rich layered oxides LiNi1-x
M
x
O2 (x = 0.1-0.2, M = Ni, Co, Mn, Al, etc.) have been widely viewed as the next generation cathode materials for Li ion battery, due to their high capacities (>200 Ah/kg), high energy densities (>800 Wh/kg), high ionic diffusivity (10-8 cm2/s) and high electronic conductivity (10-1 S/cm).[1] However, these oxides have faced a big challenge of severe structural instability. Depending on different particle sizes, morphologies and doping/alloying treatments, the materials normally have 40%-80% capacity degradation after ~100 charging/discharging cycles. Based on traditional understanding of layered oxides, three main hypothesis[2-3] have been proposed within battery research community: 1) surface phase transition and interaction, 2) bulk phase transformation, and 3) mechanical degradation involving inter-grain crack formation. However, it is still not clear which mechanism is playing the dominating role during degradation of Ni-rich layered oxides. Unfortunately, due to lack of systematic theoretical study on the thermodynamic and kinetic process of degradation upon delithiation, the fundamental driving forces and the relative kinetics are poorly understood. Therefore, in this work, we report our recent results from atomic scale Density Functional Theory modeling, which carefully simulates the processes relevant to degradation of Ni-rich layered oxides, from which we have delivered significant theoretical understanding of the above mentioned three hypothesis.

Furthermore, based on these theoretical understandings, we have performed experiments to validate the proposed surface modifications through both conventional wet chemistry coating and advanced particle Atomic Layer Deposition (ALD). These computational and experimental combined studies could provide us deeper understanding of degradation of Ni-rich layered oxides, and shed light on the future direction towards stabilized high energy cathode materials.

[1] J. Xu, F. Lin, M. M. Doeff, W. Tong, J. Mater. Chem. A, 2017, 5, 874

[2] M. D. Radin, Y. S. Meng, A. Van der Ven, etc., Adv. Energy Mater. 2017, 1602888

[3] W. Li, B. Song, A. Manthiram, Chem. Soc. Rev., 2017, 46, 3006
Modeling the Effect of Aging on the Performance Decay of a Lithium-Ion Battery during Charge-Discharge Cycling
Authors: Cho Jaeseong , Lee Myoung Kyou , Koo Boram , Shin Chee Burm
Published: February 2020

The lithium-ion battery (LIB) is the primary choice for electric vehicle (EV) applications due to its high energy density, high voltage and low self-discharge rate. The service life of LIB for EV applications is generally limited by aging and the aging of LIB depends strongly on the thermal history during usage. In order to secure the resilience of LIB for the EV applications, it is essential to develop a modelling tool that has a capability to account for the relationship between the aging and thermal history of LIB to design an optimal battery management system.

In this work, a modeling is performed to predict the effect of aging on the performance decay an LIB as well as variation of thermal behaviours during cycling for a long time. The validation of the modeling approach is provided through the comparison of the modeling results for a 14.6Ah LIB cell from LG Chem. with the experimental measurement data obtained from the cycling tests. The cycling tests were performed under the protocol of the constant-current charge and the constant-current discharge.

In Fig. 1, the discharge capacities measured at every thousand cycles for discharge rates of 1C, 3C, and 5C were compared with those calculated from the modeling. The modeling results and the experimental data on the capacity fade of the aged LIB cell are in good agreement in Fig. 1. Fig. 2 shows the temperature distributions from the experimental IR image and the modeling for the LIB at an environmental temperature of 25 ˚C at times of 240, 480, and 636 s during the CC discharge with a rate of 5C after 1000 cycles. Model predictions reasonably reproduce the experimental data.

Figure 1
CVD MoS2 Transistor Circuit for Organic Light-Emitting Diode
Authors: Kwon Hyeokjae , Lee Han Sol , Im Seongil
Published: February 2020

Like graphene, 2D semiconductors are formed by mechanical exfoliation using scotch tapes in general. Among many nanosheet materials, molybdenum disulfide (MoS2) semiconductor has been the most extensively studied, since it has displayed excellent carrier mobility, high on/off current ratio, and good subthreshold swing in a field-effect transistor (FET) form with n-type conduction. However, fabricating 2D MoS2 by the mechanical exfoliation limits the length scale only to a few micrometers. So, one of the remaining important issues is how to fabricate such 2D MoS2 in a large scale, which would open the gate toward more practical applications enabling photolithographic device/circuit patterning. Several research groups have thus recognized the issue, studying and reporting on the chemical vapor deposition (CVD) of large scale MoS2 2D sheets. Yet, only a few studies of full photolithographic patterning and integration for polygrain 2D MoS2-based devices in large scale on glass have been reported.

We demonstrate CVD-grown large scale polygrain MoS2 nanosheets and related field effect transistor (FET) circuits, which were patterned and integrated by photolithography on glass substrate. CVD MoS2 nanosheet transistors are applied to demonstrate their possibility as switching/driving elements for the pixel of organic light-emitting diode (OLED) display. The maximum mobility of MoS2 FETs either as switch or as driver was ~1 and 7 cm2/Vs at VD=1 V

Figure 1
Polypeptides As Complexing Units
Authors: Solladie Nathalie
Published: February 2020

One of our research field concerns porphyrin-functionalized a-polypeptides to control the spatial organization of the chromophores and enable exciton migration through the pool of porphyrins to mimic the light harvesting antennae of the photosynthetic system.1

In the photosynthetic system, the solar energy is collected by pigment molecules attached to the light harvesting complexes, in which the chlorophylls are held in a parallel orientation by fairly short a-helical polypeptides. When a photon hits one of the chlorophylls, the absorbed energy spreads extremely rapidly to the others until the reaction center is reached.1 Succeeding in organizing the porphyrins in a similar way as nature does should provide information about the relation existing between the orientation of the chlorophylls and the efficiency of nature in transferring an excited state over a very long distance and with minimal loss of energy.

The right-handed 310 helical conformation adopted by our poly-L-lysine functionalized with eight porphyrins induces an overlap of the chromophores (studies realized in collaboration with Prof. T. Keiderling, University of Chicago, US), which thus present sufficient electronic coupling to promote a good exciton migration within the molecular wire.

The properties of our peptides with pendant porphyrins were studied extensively in collaboration with with Professor S. Fukuzumi (Univeristy of Osaka, Japan) and applications were found as organic photovoltaic cells,2 multiple photosynthetic reaction centers3 and for the successful purification of Single-Walled Carbon Nanotubes.4

Acknowledgements

This work was supported by the CNRS and the French Ministry of Research.

References

W. Kühlbrandt, Nature
1995, 374, 497-498.

T. Hasobe, K. Saito, P. V. Kamat, V. Troiani, H. Qiu, N. Solladié, K. S. Kim, J. K. Park, D. Kim, F. D'Souza, S. Fukuzumi, J. Mater.
Chem.
2007, 39, 4160-4170.

S. Fukuzumi, K. Saito, K. Ohkubo, V. Troiani, H. Qiu, S. Gadde, F. D’Souza and N. Solladié, Phys.
Chem. Chem. Phys.
2011, 13, 17019-17022.

Kenji Saito, Vincent Troiani, Hongjin Qiu, Nathalie Solladié, Takao Sakata, Hirotaro Mori, Mitsuo Ohama, Shunichi Fukuzumi, J. Phys. Chem. C
2007, 111, 1194-1199.

Figure 1
Tetrapyrrolic Surface Coatings for Applications in Photoelectrosynthetic Fuel Production
Authors: Moore Gary F. , Beiler Anna M. , Khusnutdinova Diana , Wadsworth Brian L.
Published: February 2020

Hybrid materials capable of linking light capture and conversion technologies with the ability to drive reductive chemical transformations are attractive as components in photoelectrosynthetic cells. [1] We have recently reported methods of applying molecular surface coatings composed of metalloporphyrin redox catalysts onto solid-state substrates that are either conductive or semi-conductive. [2-5] The metalloporphyrin catalysts used in this work are capable of activating electrochemical transformations including the conversion of protons to hydrogen and carbon dioxide to carbon monoxide. In one approach, metalloporphyrin precursors are prepared via a novel synthetic strategy to yield a macrocycle with a pendent 4-vinylphenyl surface attachment group at the beta-position of the porphyrin ring structure. [2] This modification allows use of a photo-induced immobilization chemistry to attach intact metalloporphyrins to a range of (semi)conducting surfaces. In addition, we have shown that initial application of thin-film polymer surface coatings can provide a molecular interface for assembling metalloporphyrin catalysts in a subsequent wet chemical treatment step. [3] In this presentation, spectroscopic characterization of these materials coupled with electrochemical analysis will be presented. These findings offer an improved understanding of the structure and function relationships governing this class of materials.

A. M. Beiler, D. Khusnutdinova, S. I. Jacob, G. F. Moore, Ind. & Eng. Chem. Research
,
55
, 5306-5314 (2016); DOI: 10.1021/acs.iecr.6b00478

D. Khusnutdinova, A. M. Beiler, B. L. Wadsworth, S. I. Jacob, G. F. Moore, Chem. Sci., 8, 253-259 (2017); DOI: 10.1039/c6sc02664h

A. M. Beiler, D. Khusnutdinova, B. L. Wadsworth, G. F. Moore, Inorg. Chem.
,
56, 12178 (2017); DOI: 10.1021/acs.inorgchem.7b01509

A. M. Beiler, D. Khusnutdinova, S. I. Jacob, G. F. Moore, ACS Appl. Mater. Interfaces
,
8, 10038-10043 (2016); DOI: 10.1021/acsami.6b01557

B. L. Wadsworth, A. M. Beiler, D. Khusnutdinova, S. I. Jacob, G. F. Moore, ACS Catal.
6, 8048-8057 (2016); DOI: 10.1021/acscatal.6b02194

Figure 1
Fabrication of SU-8 Based Three-Dimensional Carbon Microelectrodes Array As Anode Material for Lithium Ion Batteries
Authors: Suresh Mamidi , Kakunuri Manohar , Sharma Chandra Shekhar
Published: February 2020

Introduction

The development of three-dimensional (3D) microelectrodes is essential not only to achieve high energy and power density Li-ion batteries but also to minimize the ohmic losses and therefore achieve better performance. In this work, we used SU-8, an epoxy based negative photoresist which yields hard carbon upon pyrolysis for fabricating 3D micro-post arrays as electrodes1. The SU-8 derived 3D carbon microelectrodes on Silicon (Si) wafer has been reported earlier in literature, however the capacity values were quite moderate2. This is due to the high resistance offered by Si wafer used as a collector. Our group reported recently that the gravimetric reversible capacity value may be almost doubled when SU-8 derived carbon film was prepared on stainless steel (SS) wafer as compared to Si wafer. This inspires us further to fabricate 3D carbon microelectrodes array on SS wafer and to test their electrochemical performance.

Experimental

SU-8 2100 was spin coated on cleaned SS wafer. Prebaking, UV exposure and post-exposure baking conditions were optimized to prepare SU-8 based 3D micropillars with an aspect ratio of 2 (50µm height and 25µm diameter), and 35µm spacing using photolithography. As-obtained micropillars were then pyrolysed under the controlled N2 atmosphere in a tubular furnace at 900ºC to obtain 3D carbon microelectrode arrays. As-fabricated, 3D carbon microelectrode array on SS wafer was used as working electrode while lithium foil as the counter electrode in Swagelok half-cell assembly to test their electrochemical performance using potentiostat/galvanostat.

Results and discussions

Figure 1a shows the optical profiler image of SU-8 derived 3D carbon microelectrode array. It was observed that the 3D cylindrical morphology was retained after carbonization however there was nearly 50% shrinkage. As-obtained 3D carbon microelectrode arrays were found to have 26µm height, 16µm diameter, and 40µm spacing. Galvanostatic charge-discharge experiments were carried out at 37.2 mA/g current density. These 3D carbon microelectrode arrays have shown a high discharge capacity (~600 mAh/g) even after 165 continuous charge/discharge cycles (Figure 1b). This is significantly higher than the reported values for 3D carbon micropillars on Si wafer2. A comparison of volumetric capacity was also made. Further detailed characterization of these carbon microelectrodes and their electrochemical performance with cyclic voltammetry results will be presented during the conference.

References:

Kakunuri, M. & Sharma, C. S. Photoresist Derived Carbon Films as High Capacity Anodes for Lithium Ion Battery. ECS Trans.
61, 37–43 (2014).

Teixidor, G. T., Zaouk, R. B., Park, B. Y. & Madou, M. J. Fabrication and characterization of three-dimensional carbon electrodes for lithium-ion batteries. J. Power Sources
183, 730–740 (2008).

Figure 1
Enhanced Bioelectrocatalytic Reduction of O2 By Laccase Using an Ethanol-Induced Immobilization on Nitrogen-Rich Carbon Nanofibers
Authors: Cho EunByul , Holmberg Sunshine , Ghazinejad Maziar , Rostro Magdalena , Parra Roberto , Madou Marc J
Published: February 2020

The use of carbon nanomaterials as potential alternative materials suitable for energy storage and for applications in metal-free catalytical fuel cells have been studied significantly. This has led to the development of various enzymatic catalysts for bioelectrocatalytic oxygen reduction reaction (ORR) on carbon nanomaterials to enhance their electrochemical properties. The selection of catalytic enzymes and electrodes, and immobilization of enzymes to allow direct electron transfer (DET) are highly desirable for achieving effective enzymatic biofuel cells (BFCs).

Laccases, multicopper oxidoreductases, are suitable for such needs in biofuel cells due to its thermostability, substrates-versatility, and high redox potential that can employ direct electron transfer, thus, improving bioelectrocatalytic reactions. Recent studies have revealed that electrocatalysis with laccase can be enhanced by selectively orienting laccase active sites near the electrode, promoting fast and direct electron transfer to allow high current density reached at high redox potential.

Here, we present a simple technique of immobilizing laccase on our nitrogen-rich graphitic carbon nanofibers by regulating the enzyme orientation with ethanol treatment. The effect of ethanol on laccase for electrocatalysis has been investigated electrochemically on nitrogen-rich graphitic carbon nanofibers synthesized via a stress-induced pyrolysis. Its performance is also compared to that of glass-like carbon nanofibers, glassy carbon and Toray carbon papers. Our findings show a cost-effective and time-efficient fabrication approach for enhancing bioelectrocatalytic oxygen reduction of laccase using ethanol treatment and the incorporated electrocatalytic effect of graphitic and pyridinic nitrogen groups in pyrolytic carbon nanofibers.