bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on Aqueous Redox Flow Batteries Based on Water-Soluble Quinone Redox Couples
Authors: Yang Bo , Hoober-Burkhardt Lena , Krishnamoorthy Sankarganesh , Prakash G. K. Surya , Narayan S. R. 
Published: February 2020

Abstract

Organic Redox Flow Batteries (ORBAT) based on aqueous electrolyte present a promising solution for grid-scale and distributed electrical energy storage direly needed for integrating the intermittent renewable energy sources because the proposed materials are potentially low cost, eco-friendly, and sustainable [1]. In ORBAT, water-soluble organic redox couples such as benzoquinone and anthraquinone derivatives can be used as both the positive and negative materials. These materials are exhibit fast kinetics of electron transfer and high charge capacity. The use of water as the solvent lowers the cost and makes the system safe and eco-friendly. In addition, ORBAT does not use any heavy metals. Researchers at Harvard have also been working on similar systems using bromine as the positive electrode material [2]. Thus, the overall cost can be low enough to achieve the DOE-specified target of $100/kWh for the entire battery system.
In our previous study [1], we have constructed redox flow cells based on quinone compounds, such as 4,5-Dihydroxy-1,3-benzenedisulfonic acid (DSQ) and Anthraquinone-2,6-disulfonic acid (AQDS) and measured the rechargeability and current-voltage characteristics. Since then we have conducted further cycling of these cells. No significant loss of capacity was observed over at least a 100 cycles (Figure 1 a).
However, the charge-discharge efficiency is low initially (Figure 1 b), and this is now understood to arise from the conversion of the oxidation product of DSQ by the Michael Addition reaction to the 2,4,5- trihydroxybenzene-1,3-disulfonic acid [3]. We will describe the polarization characteristics and the mechanism of this reactant transformation as studied by electrochemical methods, NMR, and UV spectroscopy. These studies offer insights into the requirements for the design of new molecules.

Acknowledgement

The work presented here was funded by ARPA-E (Open FOA DE-AR0000353) and the Loker Hydrocarbon Institute of University of Southern California.

Figure 1. Cycling experiment of 1M DSQ, 1M AQDS, 1M sulfuric acid. Charge and discharge at 80mA/cm2. a) Charge-discharge capacity. b) Charge-discharge efficiency.

References

1. Bo Yang, Lena Hoober-Burkhardt, Fang Wang, G. K. Surya Prakash, and S. R. NarayananJ. Electrochem. Soc. 2014, 161(9).
2. Brian Huskinson, Michael P. Marshak, Changwon Suh, Machael J. Aziz, etc. Nature 505 195-198 January, 2014.
3. Xu, Y.; Wen, Y.; Cheng, J.; Yanga, Y.; Xie, Z.; Cao, G. WNWEC, Nanjing, China, Sept 24-26, 2009.Volume:

Figure 1
Towards Long Cycle Life of Soluble Lead-Acid Redox Flow Batteries
Authors: Chen Hsun-Yi , Chang Chih-Wei 
Published: February 2020

A redox flow battery (RFB), with the freedom to design its power and energy capacity separately, is one of the most promising candidates for grid power management. The soluble lead acid RFB, which possesses characteristics of simple structure and inexpensive comprising materials, stands out for large-scale stationary storage. However, state-of-the-art lead-acid RFBs have limited cycle life and are not applicable to power grid applications. This study focuses on developing a single-flow, membrane-less, soluble lead acid RFB for grid-scale energy storage.
First, a pilot RFB based on soluble lead-acid chemistry and with a 2 cm2 electrode area is designed and constructed. A parasitic pump with controllable pumping rate is utilized to circulate the electrolyte through the cell. Composite electrodes comprised of carbon and adhesive polymers are fabricated through hot pressing and slurry drying techniques. Different routes have been tried to prepare methanesulfonic acid solution, which serves to dissolve lead, to achieve desired concentrations. Various materials, including 316 stainless steel and graphite, are tested for their long-term stability when they serve as positive and negative current collectors. The performance of lead-acid RFBs with different combination of components is compared. We have achieved voltage efficiency and columbic efficiency both of over 80%, and energy efficiency of over 60% for over 100 cycles of deep charge and discharge.
In addition, activation of electrodes at low current density before cycling is found to be necessary for higher charge efficiency and longer cycle life. Although the mechanism is not completely understood, we find that the activation procedure able to enhance the attachment of lead dioxide on the positive electrode surface, which in turn leads to improved electrode stability. Electrochemical impedance spectroscopy is conducted and the charge transfer resistance after activation is found to be significantly reduced. Other pertinent thermophysical properties are acquired through electrochemical measurements.
Based on our optimization experience of the pilot cell, a scaled-up, soluble lead acid RFB with a 36 cm2 area electrode is built. A magnetic drive pump is used to circulate the electrolyte through the electrolyte storage tank and the battery. The attached figure demonstrates the performance of lead acid redox flow battery with a 36cm2 of electrode area, under an operation current density of 12mA/cm2. New challenges facing scaled up lead-acid RFBs are investigated. For example, after the scaled-up lead-acid RFB is cycled for a long time, we often find certain yellow color byproduct resides at the corner of the electrode, which was rarely seen in the 2 cm2 pilot cell. We believe the byproduct is induced by non-uniform current density distribution in a larger cell. Other factors that could facilitate extension of cycle life and improvement of charge/discharge efficiency will be discussed.

Figure 1
Low Temperature Preparation and Electrochemical Properties of LiFeSi2O6
Authors: Zhou Shiliang , King Graham , Scanlon David , Sougrati Moulay-Tahar , Melot Brent 
Published: February 2020

The growing demand for Li-ion batteries requires the development of inexpensive materials that can be made in a sustainable fashion. Here we report a new low-temperature preparation for and the first electrochemical characterization of LiFeSi2O6, a hugely Earth-abundant, rock-forming mineral. We have found that LiFeSi2O6 undergoes a reversible electrochemical reaction against Li centered around 2 V with capacities near 60% of the theoretical maximum.
However, an extremely slow rate of cycling (C/200) or small particle size of LiFeSi2O6 is required to obtain a reasonable capacity, which indicates that Li+-(de)insertion in LiFeSi2O6 is kinetically hindered. To understand the origin of this kinetic hindering, we conducted Ritveld refinement of the atomic displacement parameters of LiFeSi2O6 against the neutron diffraction data obtained from the HIPD beamline at Los Alamos National Laboratory. The results not only allowed us to clarify the preferred diffusion pathway for Li+ ions in LiFeSi2O6, but also enabled us to link the kinetic hindering in the material to its structural rigidity, which is indicated by the flat-shaped atomic displacement sphere of oxygen atoms along the polyhedra linkages in the LiFeSi2O6 structure.
(Invited) Ultrasensitive Electroanalytical Detection and Study of Single Nanoparticle Catalysts
Authors: Stevenson Keith J 
Published: February 2020

The continued interest in nanoparticles (NPs) is due to their numerous properties such as active components in sensors, optics, energy conversion and energy storage applications. The development of new analytical tools for characterizing NP properties in a fast and reproducible manner is sorely needed. Especially for those to correlate structure-function relationships of NPs and optimize NPs activity for in homogeneous and heterogeneous catalysis. The precise characterization of individual NPs in terms of their size, shape and composition would faciliate better fundamental understanding. The development of "electrocatalytic amplification" is one such method where single NPs are detected by measuring electrocatalytic current (or potential) due to the electrochemical processes (oxidation/reduction of the species present in solution) occurring on the surface of the NP whenever a NP collides with an inert UME (gold, platinum, platinum oxide and carbon) which otherwise cannot catalyze the reaction.
Here we report the application of electrocatalytic amplification method employing inert (non-catalytic) UMEs (Hg, Bi, Ga) as electrodes for evaluating the catalytic activity of Pt NPs of different shapes (hexagones and cubes) for hydrazine oxidation. To precisely correlate structure function relationship of Pt NPs, Pt NPs without ligands referred as "naked Pt NPs" were used in this study. "Naked Pt NPs" were obtained by following the procedure reported previously where polyacrylate capped Pt NPs were synthesized first followed by a strong base treatment (potassium hydroxide) to remove the ligand (polyacrylate) off the NP's surface. From TEM the average size of polyacrlylate capped hexagonal and cubic Pt NPs was found to be 11.2 ± 2.8 nm and 11.8 ± 1.7 nm respectively. Hexagonal Pt NPs possess (100) and (111) facets where cubic Pt NPs possess (111) planes as preferential surface facets. Complete removal of polyacrylate ligand from the Pt NP's surface was confirmed by obtaining CVs, TGA and IR spectra of polyacrylate capped Pt NPs before and after KOH treatment. Also, Pt NPs retained their size and structure after base treatment. The integrated charge passed per spike during single NP collision for polyacrylate capped hexagonal and cubic Pt NPs concentrated over a range of (120-210) and (40-100) pC respectively. Whereas, for naked hexagonal and cubic Pt NPs the integrated charge passed per spike during single NP collision concentrated over a range of (180-400) and (60- 180) respectively. Naked Pt NPs displayed higher catalytic activity for hydrazine oxidation compared to polyacrylate capped Pt NPs of similar size and size.
Improving Seebeck Coefficient of Thermogalvanic Cells Using Polyelectrolytes
Authors: Gunawan Andrey , Tarakeshwar Pilarisetty , Buttry Daniel A. , Mujica Vladimiro , Phelan Patrick E 
Published: February 2020

Thermogalvanic cells, also known as thermoelectrochemical cells or simply as thermocells, have recently attracted a lot of attention because of their immense potential in converting low-grade thermal energy to electricity. The thermal temperature coefficient of electrode potential (α) in a thermogalvanic cell is directly proportional to the change in entropy (ΔS) of the redox reaction in the cell through the relation (α = ∂E/∂T = ΔS/nF), where E is the cell potential, T the temperature, n the number of electrons involved in the reaction, and F the Faraday’s constant. Although the nature of effects are different, α is often referred to as the Seebeck coefficient. In an ideal thermogalvanic cell, one therefore prefers to employ a redox couple exhibiting the largest α. Therefore, in the current study we discuss an alternate method to enhance ΔS for the electron transfer process. Thus, by coupling a redox process to solution phase complexation, we show that there is marked increase in both the change in entropy and the resulting α. While the change in entropy was calculated using quantum-chemical methods, α was experimentally measured for a Cu/Cu2+ thermogalvanic cell. The results indicate that a complexation of the Cu2+ species with a dissolved polymer, such as poly(acrylic acid) (PAA) or ethylenediaminetetraacetic acid (EDTA), dramatically improve α by up to 75%. We believe, that this novel approach to enhance α, would prove to be useful in the development of thermodynamically more efficient thermogalvanic cells.
Modification of Sacrificial Polymers for Low-Cost MEMS Packaging
Authors: Phillips Oluwadamilola , Kohl Paul A 
Published: February 2020

Packaging of microelectromechanical systems (MEMS) is vital to maintaining device performance and minimizing the impact of environmental threats. Packaging accounts for a substantial portion of the total cost of the MEMS device. In the approach taken here, the movable MEMS component is encapsulated by a sacrificial polymer in order to protect the device during processing. The component is then packaged in a traditional way, such as by overmolding on a substrate or lead-frame packaging. Thermal decomposition of the sacrificial polymer releases the MEMS device either during or after component packaging. A thermally decomposable sacrificial material, polypropylene carbonate (PPC) and overcoat material BCB (benzocyclobutene) was used for protection of the MEMS device during packaging. PPC decomposition products permeate through the overcoat to leave an air cavity. Control of the thermal decomposition of polypropylene carbonate is an integral part of the process because the MEMS device needs to be released at a critical point in the process.
In this study, the thermal decomposition temperature of the PPC was modified by kinetically inhibiting the thermal decomposition via end-capping. Reacting the hydroxyl-end group of polypropylene carbonate with chemical moieties such as organohalides and mono/difunctional acids alters the thermal stability of these materials. Furthermore, additives such as metal halides and multifunctional alcohols can also alter the thermal decomposition PPC. In this presentation, the status of these modified polymers in this cavity-forming MEMS packaging process will be discussed.
The Electrodeposition of Crystalline Gallium Antimonide Using Electrochemical Liquid-Liquid Solid Deposition (ec-LLS)
Authors: DeMuth Joshua James , Maldonado Stephen 
Published: February 2020

The growth of crystalline III-V semiconductor material from aqueous solutions has maintained a challenging task in the field of semiconductor electrodeposition. Electrochemical liquid-liquid solid deposition (ec-LLS) is a method in which an applied potential is used to grow crystalline semiconductors from a liquid metal electrode/solvent.1 In this study crystalline gallium antimonide (c-GaSb) films were electrodeposited from both Sb­2O3 and SbCl3 precursors in aqueous electrolyte via ec-LLS at mild temperatures (40o-90oC) and ambient pressure. The electrodeposition of c-GaSb films has been previously attempted2,3 but the deposits contained large amounts of excess antimony and required post-deposition annealing steps. However, in the present study c-GaSb films with stoichiometric amounts of Ga and Sb were obtained without any post-deposition annealing. In addition, the growth conditions were varied and the effects on the grain size, texture and composition of the resultant films were examined using X-ray diffraction, energy-dispersive X-ray spectroscopy and Raman spectroscopy. The results showed that the temperature, precursor concentration and pH were the most significant parameters that influenced the crystalline quality and composition of the as-grown films.

References:

(1) Fahrenkrug, E.; Gu, J.; Maldonado, S. J. Am. Chem. Soc.,2013,
135
, 330-339
(2) McChesney, J et al., Optical Materials, 1996, 6, 63-67

(3) Musiani, M et al., J. Appl. Electrochem., 1989, 20, 868-873
Solid Polymer Electrolytes Based on Chitosan and Europium Triflate
Authors: Silva M. M. , Alves R. , Donoso J. P. , Magon C. J. , Silva I. D. a. , Pawlicka Agnieszka 
Published: February 2020

The solid polymer electrolytes (SPEs) have been extensively studied since the pioneering work of Wright and Armand et al[1, 2]. Previous studies were focused on poly(ethylene oxide) (PEO) and lithium salts [3]. However recent research aimed at developing SPE based on natural polymers, which are interesting due to their natural abundance, low price and environmentally friendly nature [4].
Chitosan is a natural polymer obtained from chitin and it has been largely investigated due to its biodegradability, non-toxicity, absorption properties and biocompatibility.
In this presentation are described the preparation and characterization of novel systems from chitosan and europium (III) trifluoromethanesulfonate salt. The transparent samples were characterized by thermal analysis (DSC and TGA), impedance spectroscopy and electron paramagnetic resonance (EPR). The Chitosan55.04%Eu(Trif)3 sample showed the best ionic conductivity of 1.52×10-6 and 7.66×10-5 S∙cm-1 at 25ºC and 80ºC, respectively. The thermal analysis revealed that the degradation started at around 120 - 145ºC and the weight loss ranged from 15 to 40%. The EPR analysis showed a broadening of the EPR resonance lines with increasing europium contents in the chitosan membranes due to the magnetic dipole–dipole coupling and spin-spin exchange between the Eu2+ions.

ACKNOWLEDGEMENTS

We are grateful to the Fundação para a Ciência e Tecnologia (PestC/QUI/UI0686/2013, POPH/FSE for a grant SFRH/BD/97232/2013 (R. Alves)) for financial support of this work. The authors are also grateful to, FAPESP, CNPq and CAPES for financial support. M. M. Silva acknowledges CNPq, for the mobility grant provided by this institution.

REFERENCES

[1] P. V. Wright, British Polymer Journal 7 (1975) 319.
[2] M. B. Armand. J. M. Chabagno, M. J. Duclot, In Fast Ion Transport in Solids; Vashishta, P., Mundy, J. N., Shenoy, G. K., Eds.; North-Holland: Amsterdam, The Netherlands, 1979, p 131.
[3] P. K. Varshney, S. Gupta, Ionics 17 (2011) 479-483.
[4] I. S. M. Noor, S. R. Majid, A. K. Arof, D. Djurado, S. C. Neto, A. Pawlicka, Solid State Ionics 225 (2012) 649-653.
Oligothiophene-Graphene Ensembles
Authors: Tagmatarchis Nikos 
Published: February 2020

The rise of graphite exfoliation pumping up graphene’s chemistry brings significant impact towards the preparation of novel hybrid materials combining the exceptional mechanical and electronic properties of graphene sheets with those of photoinduced charge transfer from organic chromophores interacting with the carbon nanostructure. Applications including charge transfer processes demand both defect-free graphene sheets and robust chemical procedures for the chemical or supramolecular grafting of the desired organic molecules onto the sp2-honeycomb lattice of graphene. Covalent chemistry of graphene leads to strong interactions between the organic material and the graphitic skeleton, however, introduces defects at the anchoring sites, thus acting as insulators. On the other hand, when supramolecular interactions are utilized to integrate organic moieties to graphene, the resulted hybrids although may suffer from the weaker π-π interactions and the subsequent release part of the organic units to the solution, the extended aromatic lattice of graphene sheets remains intact and undisrupted, as no bond formation takes place, thus allowing for ballistic transport of charges with negligible loss of energy.
Oligothiophenes in general and terthiophenes in particular, are readily accessible organic chromophores with interesting electronic properties. The stiff skeleton of oligothiophenes and the presence of the sulfur atom generate a stable π-conjugated chain, which can interact through multiple π-π stacking forces with the sp2 graphene lattice.
In this frame, the ease of oligothiophenes chemical manipulation allows the preparation of oligothiophene-graphene ensembles showing enhanced solubility in organic solvents. The latter is justified due to the insertion of alkyl groups at 3' and 4' position of the thiophenes ring. Herein, the preparation of oligothiophene-graphene ensembles will be presented, followed by their full characterization through Raman and IR spectroscopy, TEM imaging and TGA analysis. Notably, our first data from the newly formed materials, based on electronic absorption, photoluminescence and electrochemistry, indicate the interaction of the organic units and the carbon allotrope under light irradiation.
Partial financial support from GSRT/NSRF 2007-2013 through action “Postdoctoral support” project GRAPHCELL PE5(2126) is acknowledged.
Functionalized Multi-Walled Carbon Nanotubes As Supporting Matrix for Enhancement Oxidation of Fucose on Gold Nanoparticle-Based Catalyst
Authors: Huong VU THI , Yoshikawa Hiroyuki , Hoa Le Quynh , Toake Hitoshi , Tamiya Eiichi 
Published: February 2020

Biomass extracted from brown macro-algae promises as a future renewable energy because of non-toxicity, natural availability, greenhouse gas free, and do not interfere with the human food chain. Here, we first present the extraction of energy from brown macro-algae via direct oxidation of fucose using anodic catalytic composite material of gold nanoparticles (AuNPs) sintered on functionalized multi-walled carbon nanotubes (f-MWCNTs). The combination of AuNPs/f-MWCNTs showed super catalytic activity on fucose oxidation in compare to AuNPs and f-MWCNTs only. The oxidation peak of fucose shifted to more negative peak by using AuNPs/f-MWCNT/C in compare to Au/C electrode only, while almost there is no peak can be observed in the case of f-MWCNT/C electrode. The direct fucose fuel cell performance by using AuNPs/f-MWCNT/C electrode as the anode resulted in power density of 1.923 mW cm-2, is much more higher than 0.658 mW cm-2 of AuNPs/C and 0.028 mW cm-2 of f-MWCNT/C. A small air - fucose fuel cell using 1 cm2 anode can run a LED lamp. Furthermore, a fuel cell using 16 cm2 anodic electrode modified by AuNPs/f-MWCNT with 3 mL fuel solution can keep a small fan running for at least 3 hours. The results from this research open possibility for practical application of our fuel cell with high efficiency on conversion of energy from brown macro-algae biomasses.
High Energy Density Capacitor By Plasma-Treated ALD BaTiO3 Thin Films
Authors: An Jihwan , Prinz Fritz B. 
Published: February 2020

Atomic layer deposition (ALD) is a modified chemical vapor (CVD) deposition tool, which is suitable for depositing high quality thin films or locally modifying the surface properties. Due to its advantages such as conformality, low pin-hole density, and the easiness of composition/doping control, ALD can used for engineering wide variety of thin film devices.
Crystallizing and densifying thin films to increase their relative permittivities are critical issues in fabricating high information density dynamic random access memory (DRAM) capacitors. The high process temperature (> 600 ° C) is usually necessary for thin film crystallization and densification, which could be detrimental to other components of DRAM. In this manuscript, we report a simple and novel method to simultaneously increase the dielectric constant and decrease the leakage current density of atomic layer deposited BaTiO3 thin films using post-deposition remote oxygen plasma treatment while keeping the process temperature low (250 °C). The dielectric constant increases from 53 (as-deposited) to 122 (plasma-treated) and the leakage current density decreases by one order of magnitude. The dielectric constant of the plasma-treated BaTiO3 film is one of the highest values ever reported for ultra-thin (5 nm thick) films. We ascribe such improvements to the crystallization and densification of the film induced by high-energy ion bombardments on the film surface during the plasma treatment. We think that plasma-induced crystallization presented in this work may have an immediate impact on fabricating and manufacturing DRAM capacitors due to its simplicity and compatibility with industrial standard thin film processes [1].

Acknowledgment

We thank Manufacturing Technology Center, Samsung Electronics for financial support

References

[1] J. An, et al., ACS Appl. Mater. Inter. 6 (13), pp 10656–10660 (2014)