bluuebunny/crossref_metadata_2025 huggingface dataset:
Microporous Polymer Membranes Tailored for Redox Flow Batteries
Authors: Helms Brett A. , Li Changyi , Ward Ashleigh , Doris Sean E. , Pascal Tod , Prendergast David
Published: February 2020

Redox flow batteries present unique opportunities for achieving multi-hour electrochemical energy storage at ultra-low cost. Too often, the barrier for implementing them is the unfettered migration redox active species across the ion-transporting membrane, which shorts the battery and exacerbates capacity fade. Here, we advance a new membrane platform with exceptional blocking ability for soluble polysulfides dissolved in flowable catholytes, at minimal impact to ionic conductivity. As a result, Li-S battery performance is dramatically improved, even when anode-protecting LiNO3 additives are absent.
Material Deposition into Porous Silicon Template
Authors: Harraz Farid A. , Ismail Adel A. , Al-Sayari Saleh A. , Al-Hajry Ali , Al-Assiri Mohammad S.
Published: February 2020

Porous silicon (PSi) is often fabricated by the electrochemical etching of silicon in a fluoride-based solution [1-4]. One of the unique properties of PSi layer is the ability to precisely tune the pore size and morphology through the variation of the silicon dopant type and level and controlling the applied anodic current and etching time. The compatibility of PSi with existing silicon processing technology adds another advantage. A wide range of materials including metals, conducting polymers, oxides, magnetic alloys and semiconductors can be deposited inside the pores of PSi templates by different techniques including; the electrochemical deposition, immersion plating and electroless deposition, sol-gel and chemical vapor deposition. Such deposition strategies would lead to various surface morphologies such as nanowires or nanorods, nanotubes, nanorings, nanodots and heterogeneous nano-macrostructures. The dimensions of as-formed hybrid structures can be controlled by regulating the shape and pore size of PSi template as well as the deposition conditions.

In this work, we used PSi as a template-directing synthesis of various metallic and polymeric nano-macrostructures. Firstly, preparation of various shapes and morphologies of PSi templates are given. Examples of chemical and electrochemical deposition of metals and conducting polymers are provided. We then focus on understanding of the mechanism of Cu deposition by the immersion plating method using the XPS sputter depth profiling into PSi template as a case study and discuss the processing issues associated with its deposition inside the nanoscale pores under the open-circuit condition.

Various pore diameters ranging from < 5 nm up to > 1 µm are accessible in PSi layers. Typical examples of SEM images of PSi templates, mainly ordered 5 µm macropores, 120 nm medium-sized pores and 20 nm mesopores are presented in Fig.1 [5]. Results of the synthesis and characterization of the obtained PSi-deposited materials will be presented and thoroughly discussed during the conference.

Keywords: Porous silicon; electrochemical deposition; immersion plating; Cu deposition; conducting polymer

References

F.A. Harraz, J. Sasano, T. Sakka, Y.H. Ogata, J. Electrochem. Soc., 149 (2002) C456.

F. A. Harraz, A. M. Salem, B. A. Mohamed, A. Kandil, I. A. Ibrahim. Appl. Surf. Sci., 264, (2013) 391.

F. A. Harraz. Appl. Sur. Sci., 287, (2013) 203.

F. A. Harraz, S. M. El-Sheikh, T. Sakka, Y. H. Ogata, Electrochim. Acta, 53, (2008) 6444.

K. Fukami, F. A. Harraz, T. Yamauchi, T. Sakka, Y. H. Ogata. Electrochem. Commun., 10, (2008) 56.

Figure 1
(Invited) Intrinsic Unipolar SiOx-Based Resistive Switching Memory: Characterization, Mechanism and Applications
Authors: Chang Yao-Feng , Fowler Burt , Zhou Fei , Lee Jack C.
Published: February 2020

We propose a research topic to comprehensively understand the intrinsic unipolar SiOx-based resistive-switching random-access memory (ReRAM) characteristics and mechanisms that can provide deep insights of device design and performance improvement for next-generation nonvolatile memory applications, as required for low-power portable electronics, highly-integrated of compact memory design, and other applications. Several main research targets will be pursued. Firstly, we will investigate device structures, material compositions and electrical characteristics to realize ReRAM cells with high ON/OFF ratio, low static power consumption, low switching power, and high readout-margin using CMOS compatible SiOx-based materials in both metal-insulator-semiconductor (MIS) and metal-insulator-metal (MIM), and one diode - one resistive switching element (1D-1R) architectures. These ideas will be combined with the use of horizontal and vertical device structure designs (active device size and thickness), composition optimization (SiOx, x < 2), electrical controlling (compliance current limitation, stopped voltage sweeping, and polarity effect) and external factors (series-resistance and ambient effects) for understanding and characterizations of resistive switching mechanism. Secondly, modeling of resistive switching mechanism, including temperature effect, pulse response and carrier transport behaviors will be performed, to develop a compact model in energy diagram, trap-level information, dipole polarization in SiOx resistive switching layer, even for computer-aided design (CAD) in very-large-scale integration (VLSI) design. Finally, for the first time, an intriguing non-Von Neumann computing architecture, named synapse-based neuromorphic system, will be demonstrated in SiOx-based ReRAM, combining with bio-inspiration and biomimetics process illustrations. The novel applications in the physiology and pathology discussions in reactive oxygen species (ROS) production and regulation processes will be clarified. This work will present the comprehensively investigation of SiOx-based resistive switching characteristics, mechanisms, applications for future post-CMOS devices era.
Development of Anolyte Materials for All-Organic Redox Flow Batteries
Authors: Huang Jinhua , Duan Wentao , Kowalski Jeffrey , Shkrob Ilya A , Brushett Fikile R. , Wei Xiaoliang , Zhang Lu
Published: February 2020

Energy storage systems for solar and wind power are expected to play a central role in addressing the global energy crisis and climate change concerns. Among the various strategies deployed, redox flow batteries (RFBs) are regarded as one of the most promising technologies for integration of intermittent and capricious energy resources. Unlike the traditional secondary batteries, the energy and power of RFBs are decoupled which offers remarkable flexibility as both of them can be independently scaled for different applications by controlling the size of the storage tank and/or the cell stack. Material development of redox active molecules, especially redox active organic molecules is crucial to enable the extensive deployment of this energy storage technology. Unlike the catholyte (high potential) materials that have been extensively investigated, the anolyte (low potential) molecules are still less tapped. In this presentation, our approach to the development of aromatic heterocycle based anolyte materials will be reported. The radical anion generation, the supporting electrolyte effect on the ion-pairing of the radical anion and its corresponding stability, as well as its coupling with catholyte material for an all-organic redox flow battery will be covered.
A Biomolecular Eco-Friendly Catalyst for Lithium-Oxygen Batteries
Authors: Ryu Won-Hee , Gittleson Forrest S , Taylor André D.
Published: February 2020

In recent years lithium-oxygen (Li-O2) batteries have drawn much attention due to their exceptionally high energy density, which could exceed the capable value of conventional Li-ion batteries.1, 2 Li-O2 batteries operate via surface reactions that form (discharging) and evolve (charging) solid oxide products.3, 4 To facilitate reaction reversibility, the oxygen electrode for Li-O2 cells often requires an efficient catalyst. Yet insulating solid products formed during discharging often deactivate the catalyst surface, making product evolution difficult.5 Soluble catalysts have recently been shown to improve charge transfer with isolated or poorly conductive products near the electrode/electrolyte interface.6 Choosing proper catalytic molecules is essential to reduce the barrier to oxygen evolution in the Li-O2 cell. The redox molecules directly transport the generated electrons to/from the electrode substrate, consequently lowering overpotential. While a few redox molecules (e.g. Li iodide (LiI), tetrathiafulvalene (TTF), iron phthalocyanine (FePc), and 2,2,6,6-tetramethylpinperdinyloxyl (TEMPO)) have been investigated so far,6-9 seeking a low cost and environmentally friendly alternative is desirable.

In this presentation, we report the use of a common biomolecule as a soluble, eco-friendly catalyst to promote Li-O2 reactions with reduced overpotentials. We also elucidate the chemical reaction mechanism of its operation during oxide formation and evolution. In situ observations of chemical structure in the redox molecule are essential to establish the catalytic function and further design molecules for high performance Li-O2 battery systems. Here, we discuss the catalytic effects of the redox biomolecule on the significantly improved electrochemical characteristics of a practical Li-O2 battery.

1.   D. G. Kwabi, N. Ortiz-Vitoriano, S. A. Freunberger, Y. Chen, N. Imanishi, P. G. Bruce and Y. Shao-Horn, Mrs Bull, 2014, 39, 443-452.

2.   K. G. Gallagher, S. Goebel, T. Greszler, M. Mathias, W. Oelerich, D. Eroglu and V. Srinivasan, Energy & Environmental Science, 2014, 7, 1555-1563.

3.   W. H. Ryu, F. S. Gittleson, M. Schwab, T. Goh and A. D. Taylor, Nano Lett, 2015, 15, 434-441.

4.   W. H. Ryu, T. H. Yoon, S. H. Song, S. Jeon, Y. J. Park and I. D. Kim, Nano Lett, 2013, 13, 4190-4197.

5.   F. S. Gittleson, W. H. Ryu and A. D. Taylor, ACS Appl Mater Interfaces, 2014, 6, 19017-19025.

6.   Y. H. Chen, S. A. Freunberger, Z. Q. Peng, O. Fontaine and P. G. Bruce, Nat Chem, 2013, 5, 489-494.

7.   H. D. Lim, H. Song, J. Kim, H. Gwon, Y. Bae, K. Y. Park, J. Hong, H. Kim, T. Kim, Y. H. Kim, X. Lepro, R. Ovalle-Robles, R. H. Baughman and K. Kang, Angew Chem Int Edit, 2014, 53, 3926-3931.

8.   B. J. Bergner, A. Schurmann, K. Peppler, A. Garsuch and J. Janek, J Am Chem Soc, 2014, 136, 15054-15064.

9.   D. Sun, Y. Shen, W. Zhang, L. Yu, Z. Q. Yi, W. Yin, D. Wang, Y. H. Huang, J. Wang, D. L. Wang and J. B. Goodenough, Journal of the American Chemical Society, 2014, 136, 8941-8946.
Limiting Current Densities Based on Permeability of Porous Transport Layers of PEM Fuel Cells Using a Pore Network Model
Authors: Konduru Vinaykumar , Medici Ezequiel , Allen Jeffrey S
Published: February 2020

Thermal and mass transport in the porous transport layers (PTL) of polymer electrolyte fuel cells (PEMFC) is studied using a pore network model. The pore network consists of coupled pore phase and solid phase model. The characteristics pore size distributions for the PTLs are obtained from porosimetry. At lower operating temperatures, flooding of the PTL can occur if the generated water if not removed at a suitable rate. This results in the restriction of reactant gases to the reaction site thereby reducing operational performance. In this paper the maximum current densities at which the PTL flooding occurs at different operating conditions are estimated using the calculated permeability of different PTLs. This can be used to study the relative performance of different PTLs under different operational parameters.
Various Scales of Aging Heterogeneities upon PEMFC Operation – A Link between Local MEA Materials Degradation and the Cell Performance
Authors: Dubau Laetitia , Durst Julien , Castanheira Luis , Maillard Frederic , Lamibrac Adrien , Dillet Jérôme , Maranzana Gaël , Lottin Olivier , El Kaddouri Assma , De Moor Gilles , Bas Corine , Flandin Lionel , Rossinot Elisabeth , Caqué Nicolas , Chatenet Marian
Published: February 2020

It is no secret that PEMFC performances decay upon operation, owing to the degradation of their core materials 1. Refining the data obtained from several experimental campaigns made in close collaboration between Axane and academic laboratories, it soon appeared that the materials degradations were not homogeneous within a PEMFC, whatever its operating conditions (stationary on the field or accelerated stress test at the laboratory scale) and their constitutive materials.

If one limits to the cathode active layer, there are three distinct levels of degradation heterogeneities. (i) At the scale of the MEA, the degradations are neither homogeneous along the gas channels of the bipolar plates (BP, from the inlet to the outlet, Figure 1) 2, nor along the active layer thickness (from the membrane interface to the diffusion layer interface) 2,3. (ii) The BP geometry also matters, since in the particular case of repeated start/stop and associated fuel-starvation events, harsher degradation was observed for the cathode regions facing the anode regions located under the land of the BP (Figure 2) 4. (iii) Finally, not all the cells operate and age in the same manner at the stack level (Figure 3) 5.

In any case, the degradations are strongly linked to the materials composing the MEA, but also depend on the fluidics of the cell (e.g. design of the bipolar plates and stack), which renders difficult any generalization of the conclusions obtained for a particular test.

References

                (1)           Gasteiger, H. A.; Vielstich, W.; Yokokawa, H. Handbook of Fuel Cells; John Wiley & Sons Ltd: Chichester, 2009; Vol. 5-6.

                (2)           Dubau, L.; Durst, J.; Maillard, F.; Chatenet, M.; Guétaz, L.; André, J.; Rossinot, E. Fuel Cells
2012, 12, 188.

                (3)           Ferreira, P. J.; la O', G. J.; Shao-Horn, Y.; Morgan, D.; Makharia, R.; Kocha, S.; Gasteiger, H. A. J. Electrochem. Soc.
2005, 152, A2256.

                (4)           Durst, J.; Lamibrac, A.; Charlot, F.; Dillet, J.; Castanheira, L. F.; Maranzana, G.; Dubau, L.; Maillard, F.; Chatenet, M.; Lottin, O. Appl. Catal. B: Environmental
2013, 138-139, 416.

                (5)           Dubau, L.; Castanheira, L.; Maillard, F.; Chatenet, M.; Lottin, O.; Maranzana, G.; Dillet, J.; ElKaddouri, A.; Basu, S.; De Moor, G.; Flandin, L.; Caqué, N. Int. J. Hydrogen Energy
2014, 39 21902

Figure 1
Effects of Repeated Feed-Gas Exchange Processes on Degradation Processes of Pt-Based PEFC Cathode Catalysts Studied by In-situ XAFS, STEM-EDS and Electrochemical Methods
Authors: Samjeské Gabor , Higashi Kotaro , Takao Shinobu , Sekizawa Oki , Kaneko Takuma , Nagamatsu Shinichi , Nagasawa Kensaku , Uruga Tomoya , Iwasawa Yasuhiro
Published: February 2020

Start-up/shut-down procedures of polymer electrolyte fuel cells (PEFCs) result in temporal intermediate states of the anode Pt/C catalyst at the partial surface by exposing to both hydrogen and oxygen (air) in the feed-gas exchange processes of either air or H2 into the anode compartment. The inhomogeneous gas mixing in the anode leads to oxygen reduction reaction (ORR) at a part of the anode surfaces, which causes the corresponding cathode potential to spike up to about 1.6 V and hence carbon corrosion and Pt dissolution to deteriorate MEA performances. Recently, we reported the behavior of Pt/C cathode catalysts in MEAs during anode gas exchange cycles (AGEX )1,2 and cathode gas exchange cycles (CGEX)2 as characterized by in-situ time-resolved XAFS and STEM-EDS. Further investigations in this study have been done with an MEA Pt3Co/C cathode catalyst.

The Pt3Co/C cathode catalyst gave different results from those for the Pt/C cathode catalyst under both AGEX and CGEX conditions. While both performance and ECSA of the Pt/C cathode decreased with increasing AGEX cycles, only the performance decreased with the Pt3Co/C cathode. In the degradation process by the CGEX cycles neither performance nor ECSA decreased with the Pt3Co/C, while only the ECSA decreased with the Pt/C. Pt LIII-edge white line peak intensities for the Pt3Co/C showed a larger decrease under the AGEX conditions, but less under the CGEX conditions, comparable to the results obtained for the Pt/C as shown in Figure 1.

Figure1. Mass-activities (left axis) and averaged Pt LIII WL peak heights (right axis) for Pt/C (black) and Pt3Co/C (orange and green) during AGEX (left figure) and CGEX (right figure). The in-situ XAFS were measured at top (squares, open star for Pt3Co/C), middle (triangle), and bottom (circle) positions of the MEA.

(1)     G. Samjeské et al., ECS Transactions,
64, 113-119 (2014)

(2)     G. Samjeské et al., ChemElectroChem, DOI: 10.1002/celc.201500099

Figure 1
Impact of Cell Compression on Resistance, Mass Transport, and Ultimate PEMFC Performance
Authors: Sassin Megan B. , Garsany Yannick , Gould Benjamin D. , Swider-Lyons Karen
Published: February 2020

The gas diffusion layer (GDL) plays multiple roles in the performance of a PEMFC: it provides pathways for fuel transport to and water away from the catalyst layer via the tortuous void/pore structure and it  ensures a good electronic contact between the catalyst layer and the current collector of the PEMFC stack.  A balancing act in cell assembly must be struck for the GDL to simultaneously offer the best transport pathways and electronic contact; different PEMFC operating conditions can require different assembly in terms of compression.  To gain a better understanding of this balancing act and to optimize the performance of the PEMFC, we systematically varied the compression of a single cell PEMFC and evaluated it under different operating conditions to extract the impact on contact resistance and mass transport.  Scanning electron microscopy of the GDL and catalyst layers post mortem reveal changes in the overall pore/void structure and provide further clues on the implications of compression on performance.
Silicon-Indium Tin Oxide Schottky Junction with Nickel Oxide Catalyst for Water Oxidation
Authors: Yoon Sanghwa , Lim Jae-Hong , Yoo Bongyoung
Published: February 2020

The sunlight assisted water splitting using a photoelectrochemical (PEC) cell is an attractive approach to generate pure H2 and O2 without environmental pollution. The products by PEC solar fuel conversion can be separated, stored and transported, easily. To achieve high performance of PEC cell, the photoelectrode has several considerations such as efficient light absorption, catalysts and stability under aqueous solution. While hydrogen evolution reaction is simple electrochemical reaction and fast, oxygen evolution reaction (OER) is kinetically sluggish and includes multistep proton-coupled electron transfer.1-3 Therefore, effective catalysts are vital to be high efficiency of photoanode with OER. Recently, nickel oxide (NiO) receives attention as alternative OER catalyst of RuO2 or IrO2, because of low cost and high activity. Silicon (Si) with 1.1eV band gap and wide light absorption of the solar specturm is promising materials for water splitting. However, in alkaline electrolyte, the long-term stability of Si without passivation layer is poor and there cannot be formed photovoltage between Si and electrolyte. For effective PEC water oxidation of Si, it is necessary to select suitable protection layer, effective catalyst and generate large photovoltage.4

In this research, schottky junction between n-Si and ultrathin indium tin oxide (ITO) with high work function was fabricated for water oxidation by sputtering of ITO and the NiO nanoparticles were deposited by spray deposition method at relative low temperature of 260oC.  A photocurrent density of 27.4mA/cm2 at 1.23V vs RHE, saturation current density of 37mA/cm2, and photovoltage as high as 545mV were achieved under solar illumination with 100mW/cm2(Fig. 1). In the high pH (1M KOH) electrolyte, the long-term stability of PEC water oxidation at 1.23V vs REH was observed with degradation of 34.23% for 96 hrs (Fig. 2). This work suggests the great approach to generate high voltage without n-p junction using doping process of Si and improve the performance and stability of Si photoanodes.

Reference

M. W. Kanan and D. G. Nocera, Science, 2008, 321, 1072-1075

M. Gratzel, Nature, 2001, 414, 338-344

O. Khaselev and J. A. Turner, Science, 1998, 280

J. Yang, K. Walczak, E. Anzenberg, F. M. Toma, G. Yuan, J. Beeman, A. Schwartzberg, Y. Lin, M. Hettick, A. Javey, J. W. Ager, J. Yano, H. Frei and I. D. Sharp, J. Am. Chem. Soc., 2014, 136, 6191-6194

Figure 1
Spray Pyrolyzed TiO2 / Sol Gel Dip Coated NiO Dye Sensitized Solar Cells
Authors: Murali Kollegal Ramakrishna
Published: February 2020

TiO2 films were deposited on ITO coated glass substrates using spray pyrolysis technique. 0.1 M of Ti(acac) was dissolved in ethanol and sprayed onto indium tin oxide (ITO) substrates with dimensions of 75x25 mm2 at different substrate temperatures (T=375, 400, 425 and 450ºC) and annealed at 500 ºC for 1h in air. The substrates were first cleaned with water, followed by dipping in con.HCl, acetone and ethanol successively. Finally the substrates were rinsed in deionised water and allowed to dry in a hot air oven. NiO films of different thickness were deposited by sol gel dip coating adopting the following procedure. 20 ml of  0.1 M of nickel nitrate was taken in a beaker, to this acrylamide, n,n, bis acrylamide solution was added. The pH was adjusted to 9 and a few drops of ammonium persulphate was added, just before gellation, ITO substrate coated with TiO2 films were immersed in the above mixture and withdrawn at a slow rate. The coated film was dried for 15 min and then post heat vtreated in air at different temperatures ( T = 475,500 and 525°C) for 1 hour. For characterization of the films, individual films of TiO2 and NiO films deposited under identical conditions and of the same thickness were used. With increase of heat treatment temperature, the thickness decreased and the crystallinity improved.

The XRD profiles of the annealed TiO2 film is polycrystalline in nature and oriented along A (101) and A (200) planes, A (101) being the predominant peak. The films exhibited tetragonal crystal structure and the peak intensities are in agreement with the JCPDS data (No. 21-1272). The heat treatment NiO films indicated that the patterns show (1 1 1), (2 0 0) and (2 2 0) crystal planes of bulk NiO. For dense films obtained from Et/Bu, all peaks exhibit only cubic NiO structure from JCPDS 04-0835 with (1 1 1) preferential orientation.

The optical transmittance of NiO films increased with annealing temperature due to the increase in crystallite size and decrease in defects. At a wavelength of 550 nm. The Eg
value reduced from 3.76 to 3.56 eV with increasing heat treatment temperature. Band gap of the TiO2 films was calculated from the Tauc’s plot, the band gap decreased from 3.45 eV to 3.20 eV with increase of substrate temperature.

TiO2 and TiO2/NiO electrodes were immersed in an N719 solution for 24 h to adsorb sufficient dye. Pt was used as the cathode of the DSSC, and clamped together with the TiO2/NiO anode for cell testing. The electrolyte solution was dropped between the electrodes. The I-V characteristics was measured at 100 mW cm-2
illumination.  LiI and Iodine was used as electrolyte. Bare TiO2 based DSSC cells exhibited a Voc of 450 mV and Jsc of 3.2 mA cm-2, these values increased to 690 mV and 7.0 mA cm-2 for the TiO2/NiO electrode post heat treated at 525°C. For the TiO2/NiO electrodes post heat treated at lower temperatures the values decreased.
Doped ZnO Nanorod Array for Ultra Low NO2 Sensing
Authors: Jain Rishabh , Manthina Venkata , Maric Radenka
Published: February 2020

NO2 is an important marker in the human breath for asthma whose concentration is proportional to the amount of inflammation in the lungs caused by infections. NO2 is also present in the exhaust of the vehicles and the OSHA recommends no more than 5 ppm NO2 in air. Currently 235 million people are suffering from asthma worldwide and the number is expected to increase drastically owing to the increase in global pollution level and dependence on fossil fuel. Metal oxide semiconductors such ZnO have remarkable sensing properties for, NO2. Sensor response (S) is a function of the resistance of the ZnO on inter-digitated Au electrodes which is given by the following equation:

S = Rair/Rgas , where, Rgas is the resistance of the film in presence of testing analyte and Rair is the resistance of the film in air. The gas detection occurs because of the reaction on the ZnO surface in presence of the NO2 molecule which causes a reduction in electron concentration and hence fluctuation in electrical resistance. This can be explained by the following equation:

NO2 + e- = NO+ + O-
ads

Here we report synthesis of TiO2 coated ZnO, Mg, Co, and Ag doped as well as undoped thin ZnO nanorod array directly on Au interdigitated electrodes using a low cost, environmentally friendly and large area application two-step chemical bath deposition (CBD) technique [1, 2] for selective detection of ultralow (0.1 ppm) NO2 in humid air at 280 °C. The structure and morphology of the ZnO films prepared by CBD has been probed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and high resolution transmission electron microscopy (HRTEM). The as-prepared doped and undoped ZnO sensors were tested for the detection of NO2 (0.1-5 ppm in simulated breath) in the temperature range of 50-280 ˚C as shown in the figure 1. Characteristics such as sensitivity, selectivity, limit of detection, reproducibility, and stability will be reported. Role of dopants in enhancing the selectivity will be explained. The selectivity for the interfering analytes such as humidity, CO2, NO2, H2 and ammonia will also be investigated. Finally the sensing mechanism will be discussed in detail. 

References:

[1] V. Manthina, T. Patel, A.G. Agrios, Number Density and Diameter Control of Chemical Bath Deposition of ZnO Nanorods on FTO by Forced Hydrolysis of Seed Crystals, Journal of the American Ceramic Society, 97 (2014) 1028-1034. 

[2] V. Manthina, J.P. Correa Baena, G. Liu, A.G. Agrios, ZnO–TiO2 Nanocomposite Films for High Light Harvesting Efficiency and Fast Electron Transport in Dye-Sensitized Solar Cells, The Journal of Physical Chemistry C, 116 (2012) 23864-23870.

Figure 1
Real-Time Detection of Salmonella on Fresh Apples Using Magnetoelastic Biosensors Operating Under Multi-Harmonic Resonance Modes
Authors: Du Songtao , Horikawa Shin , Hu Jiajia , Wang Fengen , Liu Yuzhe , Chin Bryan A
Published: February 2020

This paper investigates real-time detection of Salmonella on fresh apples using phage-coated magnetoelastic (ME) biosensors that operate under multi-harmonic resonance modes. The ME biosensor is a class of mass-sensitive biosensors that is being developed for rapid, on-site pathogen detection in the food system. The ME biosensor used in this work consists of a freestanding, strip-shaped ME resonator (1 mm x 0.2 mm x 30 um) as the signal transducer and E2-phage that specifically binds with the pathogen of interest. The ME resonator is made of an amorphous, ferromagnetic alloy with magnetostrictive properties and hence can be placed into mechanical resonance by an externally applied time-varying magnetic field. When this phage-coated ME biosensor comes into contact and binds specifically with the target pathogen, the mass of the biosensor increases, resulting in a decrease in the biosensor's resonant frequency. The conventional theory describes that the mass sensitivity of the ME biosensor (i.e., the ratio of the resonant frequency change to the mass change) is proportional to the harmonic, n, defined as an integer multiple of the fundamental resonant frequency (n = 1, 2, 3, ···). Hence, improved mass sensitivity can be obtained by measuring resonant frequency changes of higher harmonic modes. Additionally, measuring and analyzing multi-harmonic resonant frequencies can reduce possible false negative detection resulting from the Salmonella that are attached to the nodes of the vibrating sensors. As a proof-in-concept experiment, in-situ Salmonella detection on fresh apples was conducted. Both measurement (with phage) and control (without phage) sensors were prepared and placed directly on apples spiked with Salmonella. The sensors’ resonant frequency shifts were then measured in situ using a surface-scanning coil detector as a function of time. While the resonant frequency shifts of the control sensors remained negligible, those of the measurement sensors decreased largely as time progressed, indicating that specific binding of the Salmonella on the measurement sensors had occurred. In addition, the mass sensitivity was found to improve for higher harmonic modes (the 2nd and 3rd longitudinal modes) compared to the fundamental mode. False negative detection was also reduced, which was confirmed by inspecting the sensor surface using SEM and comparing the number of bound Salmonella to the measured frequency shift data. Hence, enhanced detection of Salmonella has been demonstrated using ME biosensors operating in multi-harmonic resonance modes.
Li4MeWO6 (Me=Ni, Mn, Co) As Positive Electrode Materials for Li-Ion Batteries
Authors: Kumakura Shinichi , Komaba Shinichi , Kubota Kei
Published: February 2020

Li-rich layered oxides, Li2MO3 (M = a variety of tetravalent metal(s), typically Mn), have been widely studied as next generation cathode materials for Li ion batteries. Recently, Li4NiTeO6 was reported as a cathode material with 1.5 Li reversible reaction.[1] It has honeycomb structure with ordered arrangement of Te and Ni similar to that of Mn and Li in Li2MO3. The hexavalent Te stabilizes divalent state of Ni ions in the structure. A reversible electrochemical performance based on the redox reaction of Ni2+/Ni4+ was observed. Here, we tried to replace Te for W in Li4NiTeO6. Tungsten is often used as a dopant for positive electrode materials to improve rate performance of Li ion batteries etc. but not popular as a main element building framework because of its heaviness, cost and electrochemical inactivity. In order to understand the influence on the structure and electrochemical properties, we synthesized mainly tungsten-containing materials, Li4MeWO6 (Me=Ni, Mn, Co) expecting hexavalent W6+ ions to stabilize the crystal structure with divalent ions and to improve the diffusion of Li ions during charge and discharge.

Li4MeWO6 was obtained by a conventional solid state reaction with heating and grinding several times. Me used was Ni, Mn, and Co to prepare Li4NiWO6, Li4MnWO6 and Li4Ni0.6Mn0.2Co0.2O6, respectively. XRD pattern of the Li4MeWO6 samples showed a single phase and clear diffraction peaks attributed to honeycomb ordering of Li, Me and W ions in the slab. The electrochemical properties for the Li4MeWO6 materials with different Me composition, were examined using coin-type lithium cells with electrolyte solution of 1M LiPF6/ EC:DMC (1:1).

Figure 1 shows charge/discharge curves of Li4NiWO6, measured with different voltage window at a constant current of 13 mA g-1. In the voltage range of 4.1 - 3.0 V, initial discharge capacity of 83 mAh g-1, corresponding to 1.1 Li extraction from Li4NiWO6 is delivered. Reversible discharge curve and good cycle stability with low polarization are observed in the voltage range, probably on the basis of Ni redox reaction. On the other hand, charging up to 4.9 V results in more than 250 mAh g-1 of charge capacity equal to 3.4 Li extraction suggesting more than 2 electron reaction of Ni2/4+couple. In addition, the polarization is getting increased by increasing upper cut-off charge voltage.

The detailed structural change during charge/discharge and the correlation between Me composition and the electrochemical performance of Li4MeWO6as positive electrode materials in Li cells will be presented.

Reference

[1] M. Sathiya, J. M. Tarascon et al., Chem. Commun, 49, 11376 (2013).

Figure 1
Effect of Glass Transition Temperature on the Energy Storage Properties of Nitroxide Radical Containing Polymers
Authors: Braunecker Wade A. , Hughes Barbara Katherine , Bobela David C. , Gennett Thomas
Published: February 2020

Stable nitroxide radical bearing polymers are attracting much attention for their application as electrode materials in organic radical batteries. These unique redox-active polymeric materials have unusually rapid rates of electron-transfer for non-conjugated polymer systems. This behavior results in unique applications in batteries because of enhanced charging capability and excellent cycling stability of the nitroxide radical functionality. A greater understanding of the inherent charge transfer limitations in such systems, particularly with respect to the relationship between performance and structure of the radical bearing polymer, are paramount to further advancements in the field. While ion transport through neutral polymer networks has been well-studied for solid polymer electrolytes consisting of charged salts incorporated inside a neutral cross-linked polymer matrix, nitroxide radical materials differ dramatically in complexity from typical solid polymer electrolytes. It has been observed that ionic motion in the former systems is coupled with segmental motion of the polymer matrix; hence, ion transport can be correlated with a polymer’s glass transition temperature (T
g). However, the T
g of radical containing polymers is expected to change dramatically and reversibly upon charging and discharging between neutral and cationic states. Therefore, it is essential to evaluate how charge transfer is affected by changes in the energetics of molecular motion. In this work, we conducted a systematic study of a class of nitroxide radical polymers for which the T
g of the materials are systematically tuned either by incorporating butyl acrylate comonomers into the backbone or by incorporating the nitroxide functionality at the terminus of a long alkyl chain. Preliminary synthesis, characterization, spectroscopic, and electrochemical data will be presented.
Novel Asymmetric Capacitors Using Intercalated Metal-Organic Framework Negative Electrodes
Authors: Ogihara Nobuhiro , Ozawa Yuka , Hiruta Osamu , Okuda Chikaaki , Kishida Yoshihiro , Ohba Nobuko
Published: February 2020

We propose a novel intercalated metal–organic framework (iMOF) electrode material, 2,6-naphthalene dicarboxylate dilithium (2,6-Naph(COOLi)2) as a next-generation negative electrode material for advanced lithium-ion batteries or asymmetric capacitors.

This iMOF material exhibits an operating potential of 0.8 V (vs. Li/Li+) between those of graphitic carbon, operating at 0.1 V, and Li4Ti5O12, operating at 1.55 V. Given the risks of an internal short circuit because of lithium metal deposition in the case of graphitic carbon electrodes and cell-voltage reduction in the case of high-operating-potential Li4Ti5O12 electrodes, this iMOF material possibly represents an advantageous battery design. In addition, because Al can be used as a current collector for this iMOF negative electrode material, whose operating potential is more positive than the potential of the Li–Al alloy reaction (0.4 V), it can potentially be used as a negative electrode material in high-voltage bipolar batteries using only Al current collector.

The proposed electrode material has an organic-inorganic layered structure of p-stacked naphthalene and tetrahedral LiO4 units (Figure 1(a)), and shows a reversible two-electron-transfer Li intercalation (220 mAh g-1) at a flat potential of 0.8 V vs. Li/Li+ with a small polarization (Figure 1(b)). 1, 2 Detailed crystal structure analysis during Li intercalation of this material shows the layered framework to be maintained and its volume change is only 0.33%. This value is much lower than that of the conventional Li-intercalated electrode materials such as graphite (ca. 10%) and Li transition metal oxides (~ 10%). Furthermore, the proposed material exhibits improved regularity of p-stacked packing via self-organization induced by heat treatment under inert atmosphere; this improved packing led to an improvement of reversible capacity as well as to a reduction of internal resistance.3

We examined the device performance of novel asymmetric capacitors comprising the iMOF negative and activated carbon positive electrodes. In this presentation, the possibility of the iMOF as the negative electrodes for asymmetric capacitors will be discussed.

References

1.           N. Ogihara, Y. Kishida, T. Ohsuna, K. Miyamoto and N. Ohba, in Meeting Abstracts of 17th International Meeting on Lithium Batteries, p. 320 (2014).

2.           N. Ogihara, T. Yasuda, Y. Kishida, T. Ohsuna, K. Miyamoto and N. Ohba, Angew. Chem. Int. Ed., 53, 11467 (2014).

3.           T. Yasuda and N. Ogihara, Chem. Commun., 50, 11565 (2014).

Figure 1
Current Status of National SOFC Projects in Japan
Authors: Kadowaki Masataka
Published: February 2020

The New Energy and Industrial Technology Development Organization (NEDO) has been conducting technology development and demonstrative research programs related to SOFC, as one of the most important and promising technologies for CO2 reduction and realizing dispersed power sources.  One of their achievements was the-first-in-the-world commercialization of SOFC-based combined heat and power (CHP) system “ENE-FARM type S” in 2011.  

In June 2014, the Ministry of Economy, Trade and Industry (METI) has compiled a Strategic Road Map for Hydrogen and Fuel Cells.  It was established, releasing fuel cells for commercial and industrial use onto the market in 2017 as one of the processes of expanding the use of fuel cell technology.  NEDO’s activities on SOFC, including a program “Technology development for promoting SOFC commercialization” , will be overviewed.
Modelling and Prediction of Deformation during Sintering of a Metal Foam Based SOFC (EVOLVE)
Authors: Xu Meng , Masson David , Ryckelynck David , Chesnaud Anthony , Thorel Alain
Published: February 2020

Stacking of cells in a SOFC stack requires that each element be perfectly flat and deprived, as much as possible, of internal stresses while maintaining their electrochemical capabilities. The EVOLVE concept introduces a metal foam based anode in which the foam plays the role of current collector, gas diffuser and thermo-mechanical deformation buffer. In addition, it means to combine all attractive features of an Electrolyte Supported Cell (ESC), i.e. the flexibility and robustness, with the advantage of an Anode Supported Cell (ASC), the electrical power supplied, in addition to the electrochemical stability under redox cycle in temperature of a Metal Supported Cell (MSC). The use of such innovative anode architecture represents a strategy to improve performances, reliability and durability of SOFCs, along with their tolerance regarding sulphur.

Owing to the very different nature and morphology of the anode components, the deformation during sintering cannot be readily anticipated. Therefore, the global deformation of the cell was modelled and simulated by Finite Element in order to optimize the shaping process. The modelling was achieved considering a phenomenological approach of the anisotropic sintering. Calculations of the deformation include morphological and mechanical characteristics of each layer as well as the dimension of the cell to anticipate any scale effects. The thermo-mechanical parameters of each component were determined experimentally by dilatometry and three-point bending tests operated under conditions identical to those of the sintering. Results provide relevant indications on components composition and morphology, and on the sintering conditions for producing flat and stackable cells.
Steam and Co-Electrolysis Sensitivity Analysis on Ni-YSZ Supported Cells
Authors: Rinaldi Giorgio , Diethelm Stefan , Van herle Jan
Published: February 2020

The present paper investigates the variation in performances in co-electrolysis of steam/CO2 on SOEC single cells caused by the progressive increase of CO2 inlet concentration and current density.

Steam electrolysis and co-electrolysis were investigated on circular Ni-YSZ supported cells produced by SOLIDpower (“ASC-700” type cells). The thin film electrolyte is constituted by YSZ and the oxygen electrode by LSCF-GDC. The active area corresponds to 12.56 cm2 (2 cm of radius).

The cells were fed with different H2O/CO2 mixtures, while keeping 10% H2 of the inlet molar flow in order to avoid re-oxidation of the Ni-YSZ support.

A sensitivity analysis was performed looking in particular at the effects of inlet gas composition, gas flows and temperature on the performances. I-V characterization and EIS measurements at different current densities were carried out for each sequence.

In steam electrolysis mode, the reference inlet molar flow was equal to 150 Nml/min (90% H20, 10% H2), at 750°C.  The I-V curve showed a voltage of 0.861V at OCV, 1.049V at 0.5 A/cm2 and 1.253V at 1 A/cm2. A sensitivity analysis was performed varying the temperature (700°C, 750°C and 800°C), the inlet air flow (100 Nml/min, 300 Nml/min and 500 Nml/min) and the total inlet fuel flow (from 8 to 16 Nml/min/cm2). In this case, the steam conversion factor was kept constant equal to 50% (adjusting the current imposed).

EIS analysis exhibits that ohmic and polarization resistances decrease with current densities lower than 0.4 A/cm2 and then rise with higher values. As expected, the increase of temperature has a positive impact on the performances, while the change of air and fuel flow slightly affects them.

In co-electrolysis mode the CO2 and H2O content was varied, keeping constant the total molar flow and the hydrogen fraction as explained before. As shown in the enclosed image, the area specific resistance (ASR) increases with the CO2 concentration in the mixture and gas transport limitation occurs at lower current densities.

Also in this case a sensitivity analysis was conducted changing the temperature (from 700°C to 800°C) and the resulting EIS plots demonstrate different ongoing processes favored at high current densities. In particular, the reverse water-gas-shift reaction plays an important role on the overall balance of the gas species, and it directly depends on temperature and inlet fuel composition.

Figure 1
Low Temperature Aqueous Precipitation Synthesis of LiMnPO4 Nano Particles for Li Ion Battery Cathodes
Authors: Vranken Thomas , Damm Hanne , D'Haen Jan , Van Bael Marlies K , Hardy An
Published: February 2020

LiMnPO4 (LMP) is regarded as a promising material for improved Li ion batteries. It is, like the already commercially applied LiFePO4 (LFP), an olivine cathode material. The main advantage is its higher potential (4.1V vs. 3.5V for LFP, with respect to Li+/Li), resulting in an energy density, about 20% higher than for LFP. The main drawbacks are its low electronic and ionic conductivities (compared to LFP). This results in reduced experimental capacities, especially at elevated (dis)charging rates1. This drawback can be circumvented, by reducing particle sizes to nano dimensions, resulting in shorter Li ion diffusion distances.

Here, we describe an optimized LMP low temperature (100°C) aqueous precipitation synthesis method2, resulting in nanoparticles (NP), with typical sizes of 50-200 nm, of which the reaction time could be significantly reduced, by modifying the base, used for inducing the precipitation. By an in-depth study of several synthesis parameters such as the flow rate, reaction time, temperature, base, … the complexity of this thermodynamically and even kinetically fragile system is emphasized. Our results show that phase pure LMP NP are only obtained in a particular small subset of these parameter values. Outside this range, secondary phases (like Li3PO4, MnHPO4 hydrate and Mn5(HPO4)2(PO4)2.4H2O (hureaulite)) are formed, or LMP is even completely absent.

The figure shows a TEM image of the LMP NP as synthesized after 24 hours at 100°C.

T. Vranken is a Ph.D. fellow of the Research Foundation – Flanders (FWO).

References

(1)         Wang, H.; Yang, Y.; Liang, Y.; Cui, L.-F.; Casalongue, H. S.; Li, Y.; Hong, G.; Cui, Y.; Dai, H. Angew. Chemie Int. Ed.
2011, 50, 7364–7368.

(2)         Delacourt, C.; Poizot, P.; Morcrette, M.; Tarascon, J.-M.; Masquelier, C. Chem. Mater.
2004, 16, 93–99.

Figure 1
Novel Silicon Nanowires-Based 3D Anodes for High-Capacity Lithium Ion Batteries
Authors: Peled Emanuel , Patolsky Fernando , Golodnitsky Diana , Freedman Kathrin , Davidi Guy , Schneier Dan
Published: February 2020

Here, we report on the scalable synthesis and characterization of novel architecture three-dimensional high-capacity amorphous SiNWs-based anodes, with focus on studying their electrochemical degradation mechanisms. We achieved an unprecedented combination of remarkable performance characteristics, high loadings of 3-15 mAh/cm2, a very low irreversible capacity (10% for the 3-4 mAh/cm2 anodes), current efficiency greater than 99.5%, cycle stability both in half cells and a LiFePO4 battery, a total capacity of 457mAh/cm2 over 204 cycles and fast charge–discharge rates (up to 2.7C at 20mA/cm2). These SiNWs-based binder-free 3D anodes have been cycled for over 200 cycles, exhibiting a stable cycle life. Notably, it was found that the growth of the continuous SEI layer thickness, and its concomitant increase in resistivity, represents the major reason for the observed capacity loss of the SiNWs-based anodes. Importantly, these SiNWs-based anodes of novel architecture meet the requirements of lithium batteries for future portable, and electric-vehicle, applications.