bluuebunny/crossref_metadata_2025 huggingface dataset:
A Versatile Bioanode with Improved Current Density and the Coulombic Efficiency through a Cascade Reaction
Authors: Zafar Muhammad Nadeem , Aslam Iqra , Murtaza Shahzad , Ludwig Roland , Gorton Lo
Published: February 2020

To improve communications between enzymes and electrodes, many different methods were developed including the use of diffusional electron mediators, the “wiring” of enzymes through immobilization in redox polymers, the functionalization of enzymes with electron relays, and the use of nanomaterials. Recently a new promising strategy was reported, in which the glycoprotein glucose oxidase (GOx) was directly electrically contacted with the electrodes after removal of the glycosylating layer. Although a lot of advances in the electrical communication between enzymes and electrodes has made it possible to fabricate new biosensors and biofuel cells, the technologies still face challenging issues, such as development of long-term stable miniaturized implantable amperometric biosensors and biofuel cells.

Our approach to the development of a glucose biofuel cell anode is based on the combination of different redox enzymes with complementary oxidation positions thus forming a reaction cascade to oxidize the substrate at more than one position. Improvements in current density and coulombic efficiency of a glucose oxidizing electrode were realized by a combination of pyranose dehydrogenase from Agaricus meleagris (AmPDH) with either glucose dehydrogenase from Glomerella cingulata (GcGDH) or cellobiose dehydrogenase from Myriococcum thermophilum (MtCDH). The mixed enzyme electrode oxidizes glucose in several combinations at the C-1, C-2 and C-3 positions of the pyranose ring. This concerted action of enzymes increases (i) the coulombic efficiency by extracting more than 2 e- per substrate molecule and (ii) the current density of the electrode when the mass-transfer of substrates becomes rate limiting. The electrodes were investigated with flow injection analysis (FIA) using different substrates under physiological conditions (pH 7.4). These investigations showed that the product of one enzyme can be used as substrate for the other enzyme and maximally 6 e- can be gained from the oxidation of one glucose molecule using mixed enzyme electrodes like AmPDHb/GcGDH/Os-polymer 2 or the AmPDHa/MtCDH/Os-polymer 1. We propose a bioanode for use in biofuel cells with an increased current density and coulombic efficiency obtained by a cascade reaction catalyzed by redox enzymes with a different site-specificity for glucose.

Key words: Bio-anode, glucose dehydrogenase, Os-polymers, pyranose dehydrogenase, cellobiose dehydrogenase, coulombic efficiency
Exploiting the Reaction of Cytochrome C with Fructose Dehydrogenase for a Multilayer Electrode Construction
Authors: Lisdat Fred , Wettstein Christoph , Kano Kenji , Wollenberger Ulla
Published: February 2020

The creation of analytical electron transfer (ET) chains based on the defined arrangement of enzymes and the redox protein cytochrome c (cyt c) on electrode surfaces represents an emerging field in bioelectronics.1,2 In this study we investigate the ET reaction of the flavin-dependent enzyme fructose dehydrogenase (FDH) with the redox protein cyt c. Two different pH optima are identified for the reaction with both proteins in solution, at acidic and neutral pH. When one reaction partner - cyt c - is immobilized on a modified gold electrode surface, ET proceeds efficiently at neutral pH which can be concluded from well shaped catalytic currents obtained in cyclic voltammograms. In addition a defined dependence on the substrate concentration is observed. In acidic media the reaction can also be verified but appears to be less efficient. This indicates that two different ET pathways between the enzyme and immobilized cyt c occur. Moreover, it is demonstrated that both partners can be assembled in a stable multilayer architecture, using the biopolymer DNA as connecting polyelectrolyte. The defined layered deposition of DNA with co-immobilized FDH and cyt c is verified by surface plasmon resonance (SPR) measurements. Prepared on electrodes, substantial catalytic currents are recorded upon addition of fructose. The response is found to be dependent on the number of layers deposited on the surface. This shows that an artificial signal chain can be constructed through multiple protein layers.

Our results contribute to the better understanding of the ET-reaction between FDH and cyt c in a surface confined state, providing the basic knowledge which may be relevant for the creation of innovative fructose sensitive electrodes.

1.         Lisdat, F.; Dronov, R.; Moehwald, H.; Scheller, F. W.; Kurth, D. G., Chemical Communications 2009, 274-283.

2.         Feifel, S. C.; Kapp, A.; Lisdat, F., in Biosensors Based on Aptamers and Enzymes, Springer 2014, 140, 253-298.
The Study on the Synergistic Effect of Anti-Poisoning Electrocatalyst and Self-Humidifying Proton Exchange Membrane for Hydrogen Fuel Cell
Authors: Deng Ran , Sim Viola , Han Wei , Yeung King Lun , Martínez-Huerta Maria Victoria , Ouyang Xin
Published: February 2020

Proton exchange membrane fuel cell (PEMFC) is an attractive power source due to its high efficiency, low emission and portable properties. However, electrode catalyst is one of main obstacles for PEMFC commercialization because of high noble metal loading and poor anti impurity-poisoning activity of the common Pt/carbon electrocatalyst. Though high temperature operation is beneficial to improve electrocatalyst activity, low glass transition temperature of traditional perfluorosulfonic acid (PFSA) polymer-based proton exchange membrane limits the operating temperature of PEMFC below 80oC. In our previous works, we developed new high-temperature self-humidifying proton exchange membrane by confining PFSA polymer within zeolite-coated porous substrate, and new anti carbon monoxide-poisoning electrocatalyst based on Pt-supported titanium carbide and titanium nitride (Pt/TiCN). Herein we combine Pt/TiCN catalyst and confined PFSA-zeolite composite membrane to improve the performance of PEMFC under high temperature, dry feed and low-purity fuel conditions. The results show that PEMFC with confined PFSA-zeolite composite membrane and Pt/TiCN catalyst outputs 120% and 13 times higher maximum power density than PEMFC with confined PFSA-zeolite composite membrane and Pt/C catalyst and PEMFC with commercial Nafion 117 membrane and Pt/C catalyst without humidification, respectively. It is believed that accelerated catalytic process on Pt/TiCN electrocatalyst contributes to the generation of more water and water retention capability of confined PFSA-zeolite composite membrane lowers proton transport resistance, thus leading to obviously improved fuel cell performance.
Single-Point Impedance Diagnostic for Internal Temperature Monitoring of Commercial Lithium-Ion Batteries
Authors: Spinner Neil S , Love Corey T , Tuttle Steven G , Rose-Pehrsson Susan L
Published: February 2020

Temperature monitoring of commercial lithium-ion batteries is critical for maintaining safety.  Extreme temperatures can result in harmful reactions, such as SEI and/or electrode decomposition, potentially leading to catastrophic thermal runaway and total battery failure [1-3].  Measuring battery temperature is typically done on the cell surface; however, this can be inaccurate, particularly during rapid heating events where differences between surface and internal temperatures can be as high as 40-50°C [4,5].  Therefore, developing methods for accurately and rapidly determining the internal temperature of lithium-ion batteries is crucial for safe operation and possible mitigation of failure events.

One technique that has been used to instantaneously monitor the state of health and internal temperature of lithium-ion batteries is Electrochemical Impedance Spectroscopy (EIS) [6-8].  Although this method is extremely effective, one key limitation is that the maximum detectable temperature has only been shown to be around 60-65°C.  Considering that decomposition reactions typically begin around 100°C or higher, it is clear the temperature window for EIS internal temperature diagnostics will need to be expanded.

In this work, a single-point EIS diagnostic was developed using a correlation between the imaginary impedance and internal temperature of a commercial 18650 lithium-ion battery, as shown in Figure 1.  This correlation was tested via several temperature vs. time programs, and Figure 2 shows results demonstrating close agreement of fit and actual temperatures up to around 95°C.

Figure Captions:

Figure 1. EIS correlation with internal temperature, along with fit, for commercial 18650 lithium-ion battery.

Figure 2. Fit vs. actual temperatures using single-point EIS diagnostic for temperature vs. time experiment on commercial 18650 lithium-ion battery.

References:

N. S. Spinner, C. R. Field, M. H. Hammond, B. A. Williams, K. M. Myers, A. L. Lubrano, S. L. Rose-Pehrsson and S. G. Tuttle, J. Power Sources, 279, 713 (2015).

T. B. Bandhauer, S. Garimella and T. F. Fuller, J. Electrochem. Soc., 158, R1 (2011).

F. Larsson and B.-E. Mellander, J. Electrochem. Soc., 161, A1611 (2014).

D. Belov and M.-H. Yang, Solid State Ionics, 179, 1816 (2008).

R. A. Leising, M. J. Palazzo, E. S. Takeuchi and K. J. Takeuchi, J. Electrochem. Soc., 148, A838 (2001).

C. T. Love, M. B. V. Virji, R. E. Rocheleau and K. E. Swider-Lyons, J. Power Sources, 266, 512 (2014).

R. Srinivasan, B. G. Carkhuff, M. H. Butler and A. C. Baisden, Electrochim. Acta, 56, 6198 (2011).

N. S. Spinner, C. T. Love, S. L. Rose-Pehrsson and S. G. Tuttle, Electrochim. Acta, Submitted.

Figure 1
Quantifying the Impact of Overdischarge on Large Format Lithium Ion Cell Safety
Authors: Fuentevilla Daphne , Mansour Azzam , Hendricks Christopher
Published: February 2020

Lithium-ion battery safety has always been a concern; however, safety is becoming increasingly important due to the proliferation of high capacity, high power cells and modules utilized in electric vehicle, grid, aerospace, and military applications. While safety measures such as battery management algorithms, thermal management, fuses, and sensors can reduce the risk of catastrophic failure, not all of the risk can be managed while the battery is active.  Self-discharge of lithium ion cells below a zero state of charge voltage, overdischarge, is one such case.  Overdischarge has generally been considered more of a performance issue than a safety concern unless coupled with recharge.  However, with battery-powered devices potentially left for long periods of time in storage, DoD interest in extending the shelf life of devices in the field, and proliferation of battery packs composed of large numbers of cells, there is an increased interest in determining limits of low voltage recharge and developing a methodology for determining safety limits. Furthermore, overdischarge is a class of safety risk that is inherent to the cell and cannot be prevented with passive protection devices.  This talk will cover safety concerns associated with overdischarge of large format lithium-ion batteries including gas generation, copper dissolution at low voltage and precipitation upon recharge, and health of the Solid Electrolyte Interphase layer.  

While the gas generation behavior of lithium-ion cells has been studied extensively[1], a methodology for assessing the gas generation prior to full thermal runaway has not been developed.  It has been demonstrated that oxygen can be released from the electrode structure due to a destabilization of the crystal lattice.[2] Additionally, electrolyte decomposition, typically during charging, contributes to gas buildup within the cell that can eventually cause rupturing of the casing.[3] We discuss methods for assessing the amount of gas generated at intermediate stages of cell abuse. Finally, we present recent data on the safety implications of copper dissolution in overdischarged large format cells.

[1] E. Roth, C. Crafts, D. Doughty, and J. McBreen, “Advanced technology development program for lithium-ion batteries: thermal abuse performance of 18650 li-ion cells,” Sandia National Laboratory Report, SAND2004-0584, 2004

[2] W. Kong, H. Li, X. Huang, and L. Chen, “Gas evolution behaviors for several cathode materials in lithium-ion batteries,” Journal of Power Sources Vol. 142, 2005, pp. 285-291.

[3] K. Kumai, H. Miyashiro, Y. Kobayashi, K. Takei, and R. Ishikawa, “Gas generation mechanism due to electrolyte decomposition in commercial lithium-ion cell,” Journal of Power Sources Vol. 81-82, 1999, pp. 715-719.
(Invited) Tailoring Polymer Structure and Composition for High-Power and High-Charge Capacity Redox Electrodes
Authors: Roberts Mark E.
Published: February 2020

Conventional batteries are efficient at delivering a continuous supply of power; however, limited discharge rates prevent their use in high power applications. Many energy systems require sources that can repetitively supply high power bursts, which include electric transportation, utilization of renewable energy sources, and portable electronics. This demand can be addressed using advanced Li-ion batteries and supercapacitors, devices that combine the high power, rapid switching, and exceptional cycle life of a capacitor with the high energy density of a battery. Electroactive conducting polymers are suitable candidates for high-power energy storage, but they are currently limited by i) the lack of nano/micro-structure control over large areas, ii) relatively low charge-capacity, and iii) material stability.

In this presentation, we will discuss our group’s recent progress on engineering high-energy and high-power electrode materials for energy storage, including scalable synthesis of nano/micro-structured polymer electrodes and integrating high-charge capacity redox polymers. To increase power, redox polymer microtubes with nanometer thickness are synthesized on large area substrates by controlling gas nucleation density, which guides to formation of nanostructured electrodes. Nanostructured electrodes exhibit superior performance at high charge/discharge rates relative to planar electrodes. To increase electrode charge capacity, redox molecules and polymer are incorporated into conducting polymer electrodes during electrochemical synthesis. The capacitance of polypyrrole electrodes can be increased from 249 F/g to 550 F/g using hydroquinone dopants, and up to 400 F/g using naturally abundant Alkali lignin. We show that the conditions for electrode synthesis, along with the type (and molecular composition) of lignin, exhibit strong correlations with electrode performance.
(Invited) Electrically Switchable Surface Properties Using End-Charged Polymers and pH-Responsive Swelling of Polymer Brushes Via Self-Consistent Field Theory
Authors: Wu David , Hu Renfeng
Published: February 2020

As electroactive or stimuli-responsive materials, polymers offer advantages related to the variety, complexity and control of the molecular structure possible with well-developed modern synthesis methods.  Choice of monomer and sequence allows coupling of response to electric fields or pH to the molecular nanostructure of the polymer chains.  We discuss two such representative materials as modeled using Self-Consistent Field Theory (SCFT). The first is an electroactive polymer brush layer composed of surface-grafted chains with a terminal charge that can fold back in response to an applied field.  We show that by judicious design of the chain sequence as a diblock copolymer with unequal block lengths, the chain folding can create a change in the apparent surface properties due to switching of the exposed block.  The second is a pH-responsive polymer brush that swells as the polymer is increasingly protonated with decreasing pH.  We show that the maximum responsiveness in swelling occurs at a pH that is shifted from the intrinsic pKa of the constituent monomers.
Development of Screen Printed Electrodes Chemically Modified with Schiff Base Films for Application in Forensic Chemistry
Authors: de Oliveira Marcelo Firmino
Published: February 2020

Electrochemical techniques have often been used to analyze a broad range of substances of forensic importance. These techniques can offer certain operational advantages such as ease of automation, potential for field use and the capability of in vivo analysis. They can also furnish information about reaction mechanisms. Additionally, chemical modification of conventional electrode surface is commonly employed for increasing specificity or selectivity in drug analysis. In the case of cocaine, for example, a variety of modifiers have been used, including polymers, Schiff bases, and biological materials.

In this work, chemically modified screen printed electrodes (CM-SPE) using different Schiff base films were employed in the voltammetric investigation of cocaine, 3,4 - methylenedioxymethanphetamine (MDMA), and morphine. Dip coating process was chosen for the surface chemical modification. Three different electrode plateforms were employed: carbon, gold, and platinum.  with methanolic solution containing different Schiff base complexes with subsequent drying step at room temperature. The voltammetric measurements were carried out in 50:50 v/v methanol:water solution containing 0.05 mol L-1 KCl and 0.1 mol L-1 LiCl as a supporting electrolyte without oxygen elimination by inert gas flow. The best results were obtained with carbon electrodes. Cocaine exhibits a well defined irreversible anodic peak current (ipa) at a potential (Epa) of 0.85V vs Ag/AgCl.

Voltammetric parameters such as Eprec, v, and tprec were optimized in this study, being obtained the values of -0.80V (vs Ag/AgCl), 120 s, and 100 mV s-1, respectively. The optimized amount of the chemical modifier was found to be 30 mg per electrode. Detection and quantification limits were obtained in 110 and 390 mmol L-1, respectively. Additionally, intra and inter-day repeatability of 2.61% and 3.77%, were obtained for cocaine determination.  It was possible to obtain a transductor for cocaine in presence of morphine and MDMA with high specificity in trace levels.

The author acknowledges FAPESP (2013/17630-7) and CAPES (25/2014 Pro-Forenses) for financial suport.
The Suppression Effect of 830nm Laser Irradiation on Porous Silicon Formation
Authors: Chiang C. -C. , Huang Y.-C , Juan P.- C. , Lo F. -S. , Lee T. -H.
Published: February 2020

The suppression effect of 830nm laser irradiation is fuond on the formation of fine porous silicon, which used hydrofluoric acid (HF) containing electrolyte for electrochemical etching. The photoluminescence (PL) profile shows a single peak at 1.94 eV corresponding to red emission at room temperature. On the laser-irradiated surface, the suppression/etching rate was changed by the laser power. Our study shows that the suppression effect of laser irradiation on the porous silicon layer be considered to a feasible technology for fabricating a uniform sub-5 nm thick porous layer.The thickness of porous layer can be precisely controled by the intensity of laser power and etching time with a tolerance in minutes.

In the study, we used 5×5 cm2, boron-doped, 1 to10 Ωcm, (100) Si specimens and the laser with wavelength of 830nm at maximum power of 5.0mW with beam size of 1.0mm. The laser institutional platform was added the polarizer to control the power of the laser beam.

The power of laser was adjusted to1.0mW, 2.0mW, 3.0mW, 4.0mW, and 5.0mW in air at room temperature. In Fig. a and b, the pictures show the suppression of formation of porous silicon by the 830nm laser at 3.0mW after electrochemical etching in HF solution with current of 100mA for 10 minutes. The thickness of porous silicon varies of  the outer region of laser-irradiated area could be observed by Field Emission Scanning Electron Microscope (FE-SEM).  A straight-line slope of a porous silicon layer between the laser irradiation and non-laser irradiation that confirms the size of Gaussian beam with the suppression phenomenon of porous silicon. We called the propagating out profie of a Gaussian beam in the laser irradiation is the transition zone of porous silicon formation (TZPS).

Figure 1
Chemical Deposition of Vanadium Oxide Electrode for Electrochemical Capacitors
Authors: Wu Haoran , Lian Keryn
Published: February 2020

INTRODUCTION

Vanadium oxides have been investigated as pseudocapacitive electrode material because of their low cost, abundance in nature and high energy capacity [1-2]. The performance of the electrodes strongly depends on the fabrication methods. However, a technique that can produce vanadium oxide with high performance, low cost and ready to scale up is yet to be developed. In this work, we demonstrate a novel and simple chemical method to deposit vanadium oxides with potential applications in electrochemical capacitors.

EXPERIMENTAL

A thin Titanium foil was ultrasonically cleaned by acetone and immersed in a 20ml 0.5M VOSO4solution. 0.3ml 1M NaOH was added to initiate a chemical precipitation process. The titanium substrate was left un-stirred in the solution for 5 days until the surface was covered by a greenish film.

Scanning electron microscopy (SEM) images were taken to examine the surface morphology. Cyclic voltammetry (CV) was used to characterize the electrochemical performance of the samples in 1 M LiCl solution.

RESULTS AND DISCUSSION

The SEM image of the surface, illustrated in Fig. 1, showed the chemical deposited vanadium oxide had layered structure with a denser layer at the bottom and a sparser and island-like layer on the top. Yet two layers are highly porous with meso- and macro- porosity, suggesting the chemical deposition enabled a large surface area that might contribute to a high capacitance. It was found the entire surface was covered by the porous vanadium oxide, showing the chemical deposition is evenly distributed on the substrate.

The cycle life of vanadium oxide electrode was shown in Fig.2, where the CV of the 1st cycle, 1000th cycle, 2000th cycle and 3000th cycle were compared. The result depicted a very rectangular and ideal capacitive behavior, suggesting the deposited vanadium oxide is suitable in electrochemical capacitors application. As a comparison, the CV of the Ti substrate showed very little capacitance. Moreover, it showed little change in CV profile from 1st to 3000thcycle, indicating that the electrode was stable for long time cycling in 1 M LiCl. There was a slight decrease in capacitance after 3000 cycle (ca. 10%), likely due to the some degradation on the surface. However, since vanadium oxide was usually reported to have poor stability due to pulverization and dissolution [1], the results in Fig. 2 is still very promising.

In addition to the morphology and electrochemical characterizations, the composition and crystal structures of the produced vanadium oxide were also investigated. These results will be presented as well.

REFERENCES

[1] G. Wang, X. Lu, Y. Ling, T. Zhai, H. Wang, Y. Tong, Y. Li, ACS Nano, 6, 10296 (2012)

[2] I.-H. Kim, J.-H. Kim, B.-W. Cho, K.-B. Kim, Journal of The Electrochemical Society, 153, A1451 (2006)

Figure 1
Inter-Particle Aggregation and Breakage in Taylor-Reactor Using CFD
Authors: Lee Hyeon-Kwon , Jeon Dong Hyup , Hong Jong-Pal , Song Jung-Hoon
Published: February 2020

Taylor reactor is composed of two co-axial cylinders where the outer one is stationary and the inner one is rotating. Recently, Taylor reactor is applied on the lithium ion battery to produce cathode material. In the reactor, complex chemical reactions and particle growth occur. The particle size and distribution have significant impact on the performance of cathode material. This study simulates inter-particle aggregation and breakage in Taylor reactor and predicts particle size and distribution. The simulated results are compared with experiment. The quadrature method of moments (QMOM) is implemented to solve a population balance equation (PBE). For the aggregation kernel, the sum of turbulence kernel and Brownian aggregation kernel is considered. The power-law kernel is taken as a breakage kernel. The mixture model is used to describe the interaction between continuous phase and dispersed phase. The effect of internal flow on the dispersed phase (i.e. particle) is investigated by changing rpm.
Studies of Mass Transport in Semiconducting Thin Film Electrodes
Authors: Parr Daniel , Meunier Carl , Roberts Ethan , Remsen Edward E. , Haverhals Luke M.
Published: February 2020

Applications of novel thin film electrodes are enabling the development of new commercial products ranging from in vivo biosensors, solar cells, and lithium-ion energy storage.  A critical consideration that enables informed engineering of working devices is mass transport of electro-active species (EAS) and electrolytes within porous thin film electrodes.  Initially we focus on the fabrication and characterization of transport within thin film electrodes fabricated from titanium dioxide, hydrogen titantate nanotubes, and zinc oxide via a sol-gel method. Characterization data for films deposited on indium tin oxide coated glass slides by doctor blade techniques are also discussed and include bright field microscopy, powder x-ray diffraction and, mass transport properties as investigated by cyclic voltammetry. Additionally we will discuss the creation and characterization of graphene nanosheets via the reduction of graphite oxide.
Electrochemical Synthezis of Co-Rh Alloys
Authors: Mech Krzysztof , Zabinski Piotr , Kowalik Remigiusz , Wojnicki Marek
Published: February 2020

Rhodium is a very important element due to a wide range of its applications in electronic devices, jewellery and catalysis. Rhodium like other platinum group metals (PGMs) presents a high catalytic activity for many chemical and electrochemical reactions. The position of rhodium on –logi0 - DGM-H plot shows its high catalytic activity for hydrogen evolution reaction (HER) [1]. The mentioned dependency may result in a conclusion that also alloys obtained through combination of elements from the transition group can demonstrate properties interesting from the point of view of catalytic activity for HER.

The present work shows results of tests over electrochemical synthesis of Co-Rh alloys from acid chloride electrolytes. Particular attention was devoted to the influence of electrolysis parameters on properties of the deposited alloys, such as the composition, structure and their morphology. The work elaborates also the mechanism responsible for formation of Co-Rh alloys through electroreduction of aquachloro- complexes of Co(II) and Rh(III) in acid environment. The identification of electrode reactions was performed based on voltammetric and electrogravimetric tests. Also, current efficiency of electrolysis was assessed. The electrolyte stability was tested with the use of UV-Vis spectrometry. The potentials range enabling the alloys synthesis was selected based on electrochemical tests. The tests included influence of concentration of Σ[CoClx(H2O)6-x]2-x (x = 0, 1, 2) and Σ[RhCly(H2O)6-y]3-y (y = 4, 5, 6), working electrode potential, electrolyte pH and temperature on the composition, structure and morphology of Co-Rh alloys deposited at potentiostatic conditions. The conducted tests indicate a possibility of alloys synthesis of a wide range of elemental composition and diversified morphology. The performed structural analysis showed a high influence of the synthesis conditions on the structure of the synthesized alloys.

[1] N. Pentland, J.O. Bockris, E. Sheldon, Hydrogen Evolution Reaction on Copper, Gold, Molybdenum, Palladium, Rhodium, and Iron - Mechanism and Measurement Technique under High Purity Conditions, J Electrochem Soc 104 (1957) 182-94.
High-Voltage, Lithium-Ion Research for Transportation Applications
Authors: Croy Jason R. , Gallagher Kevin G. , Rinaldo Steven G. , Long Brandon R. , Balasubramanian Mahalingam , Park Joong Sun , Dogan Fulya , Yang Zhenzhen , Lee Eungje , Burrell Anthony K.
Published: February 2020

An obvious way to increase the energy output of current lithium-ion chemistries is to increase the upper cutoff voltage to which cells are charged. Typical, layered NMC-based cathodes can generally cycle about ~60% of their theoretical capacity, leaving substantial stores of lithium, and energy, untapped. This limit (~60%) is due in part to the demanding cycle-life requirements of certain applications (e.g., transportation) where degradation mechanisms can prove too severe at high voltages and high states of delithiation for acceptable cell ageing. Argonne National Laboratory is conducting an extensive study into the degradation mechanisms at play when lithium-ion cells are operated at high voltages (e.g., ≥4.4 V vs. graphite). Key questions of interest focus on the role of surface vs. bulk effects, cycle-performance in full-cell systems, and the proper analysis of data to ensure meaningful and reliable results. This presentation will discuss the process and protocols of the project, some initial results, and future directions of research.
Effects of Transiotion Metal Co-Doping on the Electrochemical Properties of Li3V2-2xFexMnx(PO4)3/Graphene Cathode Material for Lithium Secondary Battery
Authors: Kim Hyun-Soo , Jeong Minchan , Jin Bong-Soo
Published: February 2020

A series of Fe and Mn co-doped Li3V2–2xFexMnx(PO4)3/graphene (x = 0, 0.005, 0.010, 0.015, 0.020, and 0.025) samples have been fabricated via a sol-gel assisted microwave synthesis method. The crystal structure and morphology of the synthesized Li3V2–2xFexMnx(PO4)3/graphene was investigated using an X-ray diffraction (XRD) and a scanning electron microscopy (SEM) systematically. Electrochemical measurement results prove that the Li3V1.98Fe0.01Mn0.01(PO4)3/graphene sample presents the best electrochemical performance as the cathode material for lithium ion batteries among the as-prepared samples in the potential ranges of 3.0–4.8 V. The resulting Li3V1.98Fe0.01Mn0.01(PO4)3/graphene cathode has an excellent specific capacity of 184.4 mAh g−1 at 0.1C rate, and even at 10C rate, it still delivers the specific capacity of 110.5 mAh g−1. The substitution of V3+ with an appropriate amount of Fe2+ and Mn4+ increases the Li+ diffusion coefficient assuming from the electrochemical impedance spectroscopy results, which is mainly responsible for the excellent electrochemical performance.

Figure 1
Electrochemical Characterization of Li4Ti5O12 By Single Particle Measurements Using a Particle - Current Collector Integrated Microelectrode
Authors: Sakurai Yoji , Kawashiri Shuhei , Utagawa Masahiro , Tsuda Takao , Tojo Tomohiro , Inada Ryoji
Published: February 2020

A single particle measurement is known as a characterization method of electrode material [1]. In a conventional single particle measurement, electrical contact between a microelectrode and an electrode particle is made while observing with an optical microscope.

Although the conventional single particle measurement can be electrochemically performed under an optical microscope by contacting the single active material particle with a Pt microfilament, the applicability of this technique is limited with respect to the size and shape of particles. Recently, we overcame the problem by using “a particle - current collector integrated microelectrode” , in which the single active material particle was directly-bonded on the tip of the microelectrode [2]. In this study, new measurement systems were constructed using the integrated microelectrode embedded in a three-electrode flange cell and a constant temperature bath in order to evaluate the electrochemical properties of Li4Ti5O12 (LTO) single particle, which includes the temperature dependency of the electrode kinetics.

Particle - current collector integrated microelectrodes were prepared as follows using a focused ion beam process unit (FIB): After attaching a tungsten probe coated with fluorinated resin to a manipulator in the FIB, the tip of the probe was cut off to expose the inner conductive probe. An ionic beam of platinum was positioned and deposited on contact between the top of the cut probe and a single LTO particle. The particle - current collector integrated microelectrode as the working electrode was assembled in a three-electrode flange cell with Li metals as the counter and reference electrodes. The electrolyte employed was 1mol/L Li(TFSI)/EC+PC(1:1 v/v%). Electrochemical measurements of the LTO single particle were carried out at 10 oC -40 oC.

Cyclic voltammograms of LTO single particle exhibited the well-defined reversible redox peaks at around 1.55V vs. Li/Li+ when the scan was initiated from reduction direction. The obtained phenomenon, higher anodic peak current than cathodic peak current, is indicative of faster reaction during Li+ extraction (i.e. discharge) than Li+ insertion (i.e. charge). At 40 oC, single LTO particle was found to deliver its 95% capacity upon discharge at 1000C. On the contrary, the capacity retention upon charge at 1000C retained only 37%. These tendencies in charge/discharge were also confirmed at all temperatures tested.

In this presentation, the peculiar reaction behavior mentioned above will be discussed in terms of reaction kinetics of LTO with lithium, through electrochemical impedance spectroscopies at various temperatures.

References

[1] I. Uchida et al., J. Power Sources, 68, 139 (1997) .

[2] Y. Sakurai et al., 65th Annual ISE Meeting, Mon S05, Lausanne, Switzerland (2014).
FeSn5@Graphene Anodes for Li-Ion and Na-Ion Batteries
Authors: Han Weiqiang , Xin Fengxia , Tian Huajun
Published: February 2020

Intermetallic FeSn5 new phase has emerged as promising alternative material for application in lithium ion batteries (LIBs) due to its highest theoretical capacity of 929 mAh g−1 for the reported M(electrochemically inactive)-Sn intermetallic anodes. However, the cycling life and rate capacity of FeSn5 electrode materials still remains a great challenge. Herein, we report for the first time a facile strategy to synthesize such well-organized composite of nano-sized FeSn5 anchored on conducting graphene sheets as an advanced anode material for Li-ion and Na-ion batteries. The in situ synthesized FeSn5@graphene composite exhibits excellent cyclic stability and good rate capability which was ascribed to the structure of homogeneous distribution of FeSn5 nanospheres on graphene sheets that can improve electrical conductivity and accommodate structural stress due to its good conductivity, high surface area and mechanical flexibility. Further, the higher capacities of FeSn5@graphene composites in LIBs than that in SIBs is ascribed to the large Na-ion radius, resulting in slow Na-ion diffusion and large volume change upon sodium insertion/extraction reactions in SIBs. For comparison, bare graphene and FeSn5 nanocrystals were also prepared and investigated in detail.
Nanoporous Structure Formatioon in Dealloying of Li Alloys
Authors: Chen Qing , Geng Ke , Sieradzki Karl
Published: February 2020

Structural instability during cycling has long been a roadblock to the path of fulfilling Li alloys’ promise as high energy-density anodes for Li-ion batteries. While most investigations into this issue deal with mechanical fracturing, we focus our discussion on morphology evolution during the discharge process1. Bi-continuous porous structures that are often associated with noble metal alloy dealloying also evolve during de-lithiation. An important issue in dealloying of Li that is inconsequential for noble metal dealloying is that of bulk diffusion of the electroactive component, which adds new complexity to this problem.  The interplay of bulk solid-state diffusion with percolation dissolution results in a variety of alternative morphologies including nonporous and core-shell particles. We use Li-Sn alloys as an exemplary system to illustrate how these factors impact the resulting dealloyed structures by investigating effects of alloy composition, dealloying rate and particle size. Our results have important implications for designing nanoporous materials from a variety of different parent-phase materials2,3.

References:

1.      Chen, Q. & Sieradzki, K. Spontaneous evolution of bicontinuous nanostructures in dealloyed Li-based systems. Nat. Mater.
12, 1102–1106 (2013).

2.      Chen, Q. Bi-Continuous Nanoporous Structure Formation via Compound Decomposition. J. Electrochem. Soc.
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Figure 1
Gradient Anode Functional Layer for Thin Y:BaZrxCe1-XO3 Electrolyte in Low-Temperature Solid Oxide Fuel Cells
Authors: Bae Kiho , Lee Sewook , Jang Dong Young , Kim Hyun Joong , Lee Hunhyeong , Shin Dongwook , Son Ji-Won , Shim Joon Hyung
Published: February 2020

Many studies have shown the great potential of proton-conducting yttrium-doped barium cerate (BCY) as a next-generation ceramic electrolyte for low-temperature solid oxide fuel cells (LT-SOFCs), but BCY’s poor chemical stability has limited its practical use. Research has confirmed that yttrium-doped barium cerate-zirconate (BCZY), substituting Zr in the B-site of BCY, can significantly mitigate the degradation of the material with little sacrifice of electrical and electrochemical performances. For successful operation of LT-SOFCs with BCZY electrolytes, the deposition of the material as a thin film and the reduction of ohmic overpotential from ion transport are necessary. In this work, we propose a novel anode design suitable for thin BCZY electrolytes (thickness < 2 μm) with a continuously gradient anode functional layer (AFL). The base BCZY powder was synthesized by the citric-nitrate method with a composition of BaCe0.5Zr0.35Y0.15O3-δ. Electrostatic slurry spray deposition (ESSD) was used to form the gradient AFL on a porous anode support and co-sintered at 1500°C. A thin, dense BCZY electrolyte was fabricated on the sintered AFL by pulsed laser deposition (PLD) at 700°C. As the cathode, porous La0.6Sr0.4CoO3-δ was deposited by PLD at room temperature. Fuel cell tests were conducted and the maximum power output of 180‒580 mW/cm2 at 450‒600°C was identified. The performance and electrochemical characteristics of the BCZY-SOFCs will be discussed in greater depth at the conference.
An Accurate and Reliable Computational Approach for the Mechanical Stress Analysis of Planar SOFC Stack
Authors: Fang Xiurong , Li Ang , Lin Zijing
Published: February 2020

Mechanical damage induced by operation under high stress conditions is one of the major factors limiting the long-term stability of SOFCs. Stress analysis is therefore important for the development the SOFC technology. To date, it is a common practice to focus the stress analysis at some interested component of an SOFC stack, e.g., PEN, glass-ceramic sealant, interconnector plate, etc. This approach is questionable as it is very difficult or even impossible to properly define the boundary conditions for the isolated component. To conduct a reliable stress analysis, it is desirable to carry out the stress computation on the entire stack. For that purpose, it is important to devise algorithm that confines the computational resource requirement at an affordable level. Here we report a grid matching method that enables the stress evaluation of the whole multi-cell SOFC stack. The basic idea of the grid matching scheme is to assign adequately fine grids for the interested stack components and their neighboring materials, while distant material components are assigned with coarse grids to reduce the computational burden. With appropriate free stress temperatures of materials, initial state of stress, material properties, boundary conditions and temperature profile of the SOFC stack, stress distributions inside the interested stack components can be calculated by solving the elastic matrix.

The method is tested with a 5-cell planar stack. The 5-cell stack is chosen so that the stress analysis with fine grids for all stack components is also affordable. The stack is of practical dimensions and material components such as the cells, frame, interconnects and glass-ceramic sealants, etc. For typical material combinations of SOFC stack and operation conditions, the stack temperature profiles were generated by a high resolution multi-physics numerical model. The test shows that the error for the maximal stress using coarse grids is limited to the order of 10% in comparison with that with fine grids for all stack components. In other words, the grid matching scheme is confirmed to be a computationally efficient and satisfactorily accurate method for the stress analysis. However, the maximal stress of a stack component evaluated with the commonly adopted method using a free boundary condition for the interested component is one order of magnitude smaller than the correct result. On the other hand, the stress of a stack component evaluated with a stiff boundary condition can be a few orders of magnitude higher than the true result. Clearly, the conventional stress analyzing approach with isolated stack components is prone to produce misleading results.

The proposed stress analysis method is valuable for reliably identifying stack components susceptible to mechanical damage. It can be used to improve the design of SOFC stack and to make informed selections of operating conditions.
Study of Water Gas Shift Reaction over Ceria Based Catalysts in Solid Oxide Fuel Cells
Authors: Tepamatr Pannipa , Buarod Eumporn , Laosiripojana Navadol , Charojrochkul Sumittra
Published: February 2020

The production of hydrogen with low CO concentration from ethanol steam reforming for use in solid oxide fuel cell has been studied. The performance of tubular SOFC with internal reforming of ethanol in the anode side integrated with water gas shift reaction which is situated at low temperature side of tubular SOFC is studied to compare with a conventional tubular SOFC. The preparation method of Ni supported ceria based catalysts SOFC anode is also taken into consideration. The structural properties, particle size changes and the microstructure of the anodes are investigated using X-ray diffraction and scanning electron microscopy as well as the performance investigation. The Thermogravimetric and SEM analyses are employed to mainly characterize the carbonaceous deposits formed.
Performance Characteristics of a Micro-tubular Solid Oxide Fuel Cell Operated with a Fuel-rich Methane Flame
Authors: Wang Yuqing , Shi Yixiang , Cai Ningsheng , Ye Xiaofeng , Wang Shaorong
Published: February 2020

A micro-tubular solid oxide fuel cell (SOFC) is directly combined with a fuel-rich methane flame in a simple, "no-chamber" setup. The multi-element diffusion flat flame burner (MEDB) is served as a fuel reformer and implements the quick starting process for the flame fuel cell. Experiments are performed based on novel anode supported micro-tubular SOFC cells and a multi-element diffusion flame burner for various equivalence ratios and flow rates. The SOFC is directly heated up by the flame from room temperature to operating temperature in less than 120 s. The maximum power generated by the fuel cell reached 0.45 W at the equivalence ratio of 1.2. The cell was operated for 8 hours at the equivalence ratio of 1.2 at a fixed voltage of 0.45 V without significant performance degradation. A transient two-dimensional SOFC model is developed to analyze the transient temperature field and the associated thermal stresses of the SOFC when the cell is suddenly exposed to a high temperature flame. The thermal shock resistance of the direct flame micro-tubular SOFC is analyzed and the result shows the excellent performance characteristics of the micro-tubular cell in the aspect of thermal shock resistance.

Figure 1
Investigation of 2R-Cell Degradation under Thermal Cycling and RedOx Cycling Conditions by Electrochemical Impedance Spectroscopy
Authors: Diethelm Stefan , Singh Vaibhav , Van herle Jan
Published: February 2020

The prevalent anode supported thin electrolyte solid oxide fuel cells (ASC) used today are highly susceptible to failure under redox conditions. The expansion caused during the oxidation of Ni to NiO can destroy the support, leading to irreversible cell damage. To counter this problem, Fiaxell SOFC Technologies (Switzerland) has engineered the microstructure of their cells, to confer added redox stability to their anode supported cell (2R-cell™). This commercial cell was investigated within the Eurostars-Roxsolidcell project against thermal and redox cycling.

A 2R-cell with a 10cm2 active area LSCF cathode on a CGO buffer layer, was placed between alumina felts, mounted inside a seal-less open flange setup kept in an oven, and operated at a temperature of 780°C. A nickel foam and a gold grid were used for the current collection at the anode and cathode respectively. Dry hydrogen (180 Nml/min) was fed to the anode and air (500 Nml/min) to the cathode. 20 thermal cycles were performed between 780 and 100°C, using 200°C/h heating ramps and natural cooling, followed by 20 redox cycles, during which air was fed to the anode for 1 hour at 780°C, causing the cell potential to drop to zero.

V-i polarisation curves and electrochemical impedance spectroscopy (EIS) measurements were performed before and after each consecutive cycle in order to monitor the performance losses. The OCV remained stable during the whole test whereas the area specific resistance (ASR) measured at 0.5 A/cm2 increased by +1.3 mΩcm2 per thermal cycle and by +1.8 mΩcm2per redox cycle. The EIS measurements showed that the degradation during the thermal cycling was mainly due to an increase of the ohmic losses. In the case of the redox-cycling, the cell degradation after stabilisation principally came from high frequency polarisation losses (cf. Figure), which were attributed to changes in the anode functional layer microstructure.

The cell was examined after the test by scanning electron microscopy (SEM). No delamination of the cathode was observed, however, fragmentation of the anode active layer was apparent.

Figure 1
Elaboration and Electrochemical Characterizations of up-Scaled Protonic Ceramic Cells
Authors: Dailly Julian , Ancelin Marie , Marrony Mathieu
Published: February 2020

Protonic Ceramic Cell in fuel cell mode (PCFC) is benefit to produce water at the air electrode side, avoiding the dilution of the fuel. Moreover, co-generation of heat and electricity is possible in this temperature range and ageing and reactivity of materials should be less critical than these observed at higher temperature. Proton Conducting Ceramic Cell is now widely investigated for a variety of applications, in particular fuel cell, steam electrolysis and hydrogen separation but such technology has to face to a low industrial scale maturity.

In the frame of METPROCELL project supported by European Community’s 7thFramework Programme (FP7/2011-2014) for the Fuel Cells and Hydrogen Joint Technology Initiative and coordinated by TECNALIA (SP), up-scaled anode-supported cells (ASC) have been elaborated by wet chemical routes. ASC requires the use of tape-casting method in order to manufacture the support. Then, both electrolyte and cathode are screen-printed on the NiO-electrolyte substrate (cf. Figure 1).

Based on previous works [1-3], promising performances (170 mW/cm² at 0.7V, 600°C, cf. Figure 2) and long term testing (thousand hours) have been measured on middle-scaled protonic cells (20 cm²). Microstructure evidenced by SEM analysis and electrochemical performances (IV-curves, Impedance Spectroscopy measurement) as well as durability measurement will be presented and discussed.

[1] Taillades G., Dailly J., Taillades-Jacquin M., Mauvy F., Essouhmi A., Marrony M., Lalanne C., Fourcade S., Jones D.J., Grenier J.-C., Rozière J., “Intermediate temprerature anode-supported fuel cell based on BaCe0,9Y0,1O3-
d electrolyte with novel Pr2NiO4 cathode”, Fuel Cells (10), 2010, 166

[2] Dailly J., Marrony M., Taillades G., Taillades-Jacquin M., Grimaud A., Mauvy F., Louradour E., Salmi J., “Evaluation of proton conducting BCY10-based anode supported cells by co-pressing method: Up-scaling, performances and durability”, Journal of Power Sources (255), 2014, 302-307

[3] Dailly J., Marrony M., “BCY-based proton conducting ceramic cell: 1000 h of long term testing in fuel cell application”, Journal of Power Sources (240), 2013, 323-327

Figure 1