bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrochromic Devices with Ionic Liquid Based Electrolyte By Room Temperature Process
Authors: Kim Haekyoung , Lee So Hee
Published: February 2020

Electrochromic devices (EC), which dynamically change colour under applied potential, are widely studied for use in energy-efficient smart windows. To improve the viability of smart windows, many researchers are utilizing nanomaterials, which can provide electrochromic devices with improved coloration efficiencies, faster switching times, longer cycle lives, and potentially reduced costs. The flexible electrochromic films are promising film for applications in automobiles, buildings, etc.

Here, we synthesized nanostructured tungsten trioxide (WO3) particles for electrochromic materials. The thin layers with nanostructured materials of WO3 inks were coated at room temperature, solution-processed method. For comparing the effects of electrolyte, electrochromic devices were fabricated with various kind of electrolyte, which can be optimized to obtain higher performances. Two types of polymer based electrolytes were fabricated and characterized. The operation voltages were controlled with electrolyte types and compositions. Ionic liquid based electrolyte showed higher ionic conductivity than liquid type or polymer type electrolyte. Also EC with the liquid electrolyte exhibited 40% of coloring/bleaching efficiencies and EC with the polymer gel electrolyte 60%. All solid EC could be fabricated with the polymer gel electrolyte, which exhibited the higher coloring / bleaching efficiencies than that with the liquid. The effects of composition and process variables will be discussed.
The Ionogel of N-Butyl-N-Methylpyrrolidinum Bis(trifluoromethanesulfonyl) Imide and Polyvinylidenefluoride-Co-Hexafluoropropylene for Flexible Lithium Ion Battery
Authors: Chen Hwang-Sheng , Chang Chien-Min , Lee Ching-Feng , Wang Pin-Han , Chen-Yang Yui Whei
Published: February 2020

Rechargeable lithium ion batteries (LIBs) have been applied in portable electronics and electricity powered transportation due to the high energy and power density. Unlike the traditional batteries packed in a cylindrical type, currently, most LIBs used in the consumer electronics (like smart phones and pads) are prismatic batteries. To meet the requirement of the electronics with particular shape such as wearable devices the flexible energy storage devices have been developed. For the safety concern, the solid electrolytes, such as polymer electrolyte, are developed to avoid leakage of liquid electrolyte. Nevertheless, the larger interfacial resistance between the solid electrolyte and electrodes and less flexibility reduced its application. Therefore, the gel-type electrolytes are favored because lithium ion is more easily to transport in gel electrolyte than solid electrolyte. Yet, as reported, certain amount of the organic solvents such as ethylene carbonate (EC), propylene carbonate (PC), dimethyl carbonate (DMC), and diethyl carbonate (DEC) have been usually used with polymers in the traditional gel electrolytes, causing the suspicion of solvent leakage. In this work, the solvent-free polymer-based ionogel electrolyte (IGE) composed of nonflammable and thermally stable N-butyl-N-methylpyrrolidinum bis(trifluorome­thanesulfonyl) imide (PYR14TFSI) room temperature ionic liquid and polyvinylidenefluoride-co-hexafluoropropylene (P(VdF-HFP)) are prepared by the solution casting method. The thermal and electrochemical properties are determined by the DSC and DMA measurements. The electrical properties are investigated by the linear sweep voltammetry, cyclic voltammetry and impedance spectroscopy. It is found that the as-prepared ionogel electrolytes are flexible self-standing films with wide electrochemical windows. The best conductivity obtained at room temperature is 6.0 × 10−4 S cm−1. The highest capacity of the half-cell (Li/IGE/LiFePO4) achieves 143 mA h g-1 at 0.2C rate. And even after 50 cycles, the capacity retains 135 mA h g-1at 0.2C. This study reveals that the ionogel electrolyte is a promising safe electrolyte for application in the flexible LIBs.

Acknowledge:

The authors gratefully acknowledge the Ministry of Science and Technology and Chung Yuan Christian University, Taiwan, R. O. C. for supporting this research work.
(Invited) Direct Comparison of Molecular and Metal Oxide Catalysts on Hematite for Photoelectrochemical Water Oxidation
Authors: Wang Dunwei
Published: February 2020

Photoelectrochemical (PEC) water splitting promises a direct route toward solar-to-chemical energy conversion.  To address the challenges associated with the slow kinetics of complex reactions such as water oxidation, catalysts have been applied onto photoelectrodes.  While PEC performance improvement is often reported, the detailed mechanisms underpinning the improvements are poorly understood.  In the case of heterogeneous oxide-based catalysts such as Co-phosphate, NiFeOx and IrOx, various electrochemical and spectroscopic studies have pointed to the slowdown of surface recombination as a key reason for the improvement.  Due to the complex chemistries involved by these heterogeneous catalysts, however, little is known about whether fast charge transfer plays a role.  Here we report a study that corrects this deficiency.  Our strategy is to directly compare two catalysts systems, heterogenized Ir-complex water oxidation catalysts (het-WOC) and heterogeneous IrOx catalysts, on hematite photoanode.  Using a combination of intensity modulated photocurrent spectroscopy (IMPS), photoelectrochemical impedance spectroscopy (PEIS) and kinetic isotope effect (KIE), we present compelling evidence that points the different functional mechanisms exhibited by the two different types of catalysts.  The het-WOC improves the performance of hematite by speeding up hole transfer for water oxidation.  The surface recombination rates remain unchanged.  The IrOx catalysts, on the other hand, slows down surface recombination.  New understandings of the photoelectrode|water interface are estabilished.
Splitting Water from Vapor Feeds: Towards Air-Based Solar-Hydrogen Generators
Authors: Modestino Miguel A. , Hashemi Mohammad H. , Gregory Daniel , Moser Christophe , Psaltis Demetri
Published: February 2020

Electrochemical water-splitting devices can contribute to increase the share of renewable sources in today’s energy landscape. Simplifying the operation of state-of-the-art electrolysis systems could help drive their large scale deployment. One alternative for the simplification of electrolyzers is the implementation of systems that can operate directly with water vapor feeds. Operation under vapor conditions brings with it several advantages: a reduced water-splitting potential, the elimination of catalysis limitations from bubble formation, and a slow-down of the degradation processes of the materials involved in the water-splitting process. In this study, we introduce a microstructured device that can produce hydrogen from humid ambient air streams.1 The device is composed of interdigitated microelectrodes that are covered by a thin ionomer film (Nafion®) (< 1 µm). Water diffuses through this film and is oxidized at the anode interface to generate oxygen and protons. Protons then migrate through the film towards the cathode side and are reduced to produce hydrogen. This presentation will provide insights into the multiple transport and electrochemical processes taking place inside of the ionomer and that affect the overall device performance. The effects of parameters such as electrodes dimensions, interelectrode separation, electrocatalysts selection and ionomer processing were studied, and their effects in the operation of the device will be discussed. We demonstrate that large ionic resistances in the devices limit the current densities achievable, and that minimizing the pathways for proton transport can result in current densities higher than 10 mA/cm2at 1.8 V. Lastly, strategies towards the integration of these air-based electrolysis components into solar-hydrogen generators will be presented. 

1. M. A. Modestino, M. Dumortier, M. Hashemi, S. Haussener, C. Moser and D. Psaltis, Lab on a Chip, 2015, 15, 2287-2296.

Figure 1
Bipolar Electrodeposition: A Wireless Method for Deposition of Electrocatalysts Onto Semiconducting Particles
Authors: Gaieck William , Tkacz Kevin , Yaghoubi Houman , Ardo Shane
Published: February 2020

Global climate change due to combustion of fossil fuels and a lack of grid-scale energy storage will continue to negatively affect our environment and impede our ability to diversify energy sources and increase energy independence. However, if we can harness the power of the Sun, much like plants, then we can achieve a sustainable, net carbon neutral future with inherent energy storage capacity in chemical bonds.

Solar photoelectrochemical water splitting produces H2, which can be used as a fuel. Proposed technologies to achieve this photochemistry typically use either a separate photovoltaic and electrolyzer, or an integrated wafer-based system. Unfortunately, these systems are costly, relying on relatively large quantities of precious metal electrocatalysts and intensive fabrication/processing methods. In contrast to these designs is the particle slurry reactor where the hydrogen evolution reaction and the oxygen evolution reaction are separated into different compartments, connected ionically and electronically via a solution redox shuttle, and stacked optically in series. This design is predicted to be cost-competitive with hydrogen produced from fossil fuels on an energy equivalent basis.    

Herein, we report on the reductive and oxidative depositions of electrocatalysts (e.g. Pt, Au, CoOPi, NiMo, and NiFe(O)OH) on state-of-the-art semiconducting nanoparticles (e.g. TiO2, WO3, and BiVO4). The unique aspect of this work is that this deposition occurs in the bulk without physically contacting the particles with electrodes. Instead, bipolar electrochemistry is used to electrodeposit these catalysts, which is a wireless, non-contact technique. After deposition, the composite materials were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and x-ray diffraction (XRD) to determine the efficiency of the deposition process. Using a variety of electrochemistry techniques, electrodes of these materials will be fabricated and evaluated for the efficiency for either the hydrogen or oxygen evolution reaction. Deposition of electrocatalysts was controlled by changing the particle and electrolyte concentrations, the solution viscosity, and the applied bias. We show that these controls allow tuning of the morphology, geometry, and material deposition of the electrocatalysts. This work expands on the robustness of bipolar electrochemical techniques and suggests that a flowable bipolar electrochemical system may allow more control and flexibility of electrocatalyst deposition than other bulk deposition methods. This work was supported by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Incubator Program under Award No. DE-EE0006963.
(Invited) Applications of Multivariate Methods in the Study of Ionomer Properties
Authors: Korzeniewski Carol , Zhang Pei , Liang Ying
Published: February 2020

Multivariate data analysis methods are being applied in conjunction with vibrational spectroscopic measurements to gain insights into structure and physical properties of ionomer materials.  Infrared and confocal Raman spectroscopy techniques are being adapted to investigate (i) fluorinated ionomer standards that span a range of equivalent weight and (ii) membrane samples with varying tensile properties.  Partial least squares (PLS) modeling applied to mid-infrared spectral data sets measured using the attenuated total reflection (ATR) technique is robust in predicting ionomer equivalent weight from measurements on calibration samples.  The experimental approach, statistical uncertainties and extension to confocal Raman experiments will be discussed.  

In relation to membrane structural and tensile properties, vibrational spectra that follow transitions between dispersion, gel and solid membrane ionomer forms are being scrutinized.  Least-squares modeling and principal component analysis (PCA) used in combination enhances the ability to resolve spectral features associated with molecular components of the sample that evolve during processing (Figure 1) and to quantitatively track changes in composition over time.  Figure 1 shows results from confocal Raman tracking of aqueous Nafion ionomer dispersion through a gel phase.  PCA and least-squares modeling were applied to data within the shaded region to extract the indicated spectral components.  For membrane processed under different thermal treatments, PLS regression is being applied to examine the correlation between tensile strength and molecular scale structure probed by vibrational spectra.

Figure 1
(Invited) Metal Hydride-Air Batteries for Large-Scale Energy Storage Systems
Authors: Bugga Ratnakumar V , Fultz Brent , Addison Dan
Published: February 2020

The poor safety behavior of Li-ion batteries necessitates complex charge electronics, elaborate thermal management and suitable mechanical reinforcements.  These would result in reduced system-level energy densities, compared to the cell-level values, and also higher battery costs.  In contrast, the aqueous systems, especially the metal-air systems that can provide high specific energies and energy densities look more appealing due to their inherent safety. Under an ARPA-E sponsored program, we (JPL, Caltech and Liox) are developing low cost and safe rechargeable metal-hydride/air batteries with high energy densities (200 Wh/kg and 400 Wh/l at cell level) for electric vehicle applications.  Our effort is focused on developing: i) new metal hydride alloys with higher hydrogen absorption capacities, ii) stable low-cost electro-catalysts for air cathodes, iii) new cell and stack designs and iv) simpler water management schemes.

We have been developing metal hydride alloys of vanadium-based quaternary BCC alloys (Ti-V-Ni-Cr) as anode materials, low-cost perovskite-based and Ni-Fe-Co layered double hydroxide catalysts for oxygen electrodes, and cell and system designs that minimize thermal and concentration gradients.  In this paper, we will describe some of our recent results on this technology.
Vanadium Sulfate As New Electrode Material for Na Ion Batteries
Authors: Pralong Valerie , Gnanavel Muthaiyan , Caignaert Vincent , Raveau Bernard , Lebedev Oleg
Published: February 2020

The design of new materials that provide high energy densities and long cycle life together with being economic and environmental benign is crucial for the energy storage. Therefore, the soft chemistry used to prepare the original frameworks, new structures is in perfect appropriateness with such a target. Our research is focused on the synthesis by soft chemistry of new “metastable” frameworks with large tunnels or layered structures at low temperature. We will discuss on our strategies to generate original framework showing ionic conductivity. The first approach is based on topotactic reactions starting from existing ionic conductors with a compact anionic framework [1]. In this case, we will show that the lithium/sodium insertion leads to new rock salt type structure. The second approach is related to polyanionic frameworks [2]. In order to favor reactivity, we are using protonic materials containing transition elements with adequate redox potential (Fe, Mn). We will show for example that lithium or sodium insertion into the jarosite hydroxysulfate phase NaFe3(SO4)2(OH)6 leads to an amorphous phase Na3Fe3(SO4)2(OH)6 which exhibits a reversible electrochemical sodium intercalation/deintercalation through a solid solution-like process, leading back to the jarosite NaFe3(SO4)2(OH)6, at  2.72V and a capacity of 100 mAh/g at C/20. This unique topotactic reaction between an amorphous and a well crystallized phase is interpreted on the basis of the formation of an inorganic polymer and will be discuss in the presentation.

V. Pralong, V. Gopal, V. Caignaert, et al., Chem. Mat. Com., 2012, 24, 12; V. Pralong, Progress in Solid State Chem., 2009, 37, 4, 262-277; V. Gopal, V. Pralong, et al., Electrochem. Com., 40, 100-102, 2014; V. Pralong et al., Inorg. Chem., 53, 522, 2014

M. A. Reddy, V. Pralong, V. Caignaert, et al., Electrochem. Com., 2009, 11 1807; V. Pralong, V. Caignaert, B. Raveau, J. Mater. Chem., 2011, 21, 12188; M. Gnanavel et al., Chem Mater., 26, 4521, 2014
Low-Cost Organic Redox Materials for Safe Energy Storage
Authors: Yao Yan , Liang Yanliang , Jing Yan , Gheytani Saman , Lee Kuan-Yi
Published: February 2020

We report the first successful demonstration of a “π-conjugated redox polymer” simultaneously featuring a π- conjugated backbone and integrated redox sites, which can be stably and reversibly n-doped to a high doping level of 2.0 with significantly enhanced electronic conductivity. When evaluated as a charge storage material for rechargeable Li batteries, P(NDI2OD-T2) delivers 95% of its theoretical capacity at a high rate of 100C (72 s per charge−discharge cycle) under practical measurement conditions as well as 96% capacity retention after 3000 cycles of deep discharge−charge. Electrochemical, impedance, and charge-transport measurements unambiguously demonstrate that the ultrafast electrode kinetics of P(NDI2OD-T2) are attributed to the high electronic conductivity of the polymer in the heavily n-doped state.  We will also discuss its application as the active electrode material in aqueous batteries.
Study of Electrodeposited Zinc Morphology in Rechargeable Alkaline Batteries
Authors: Wei Xia , Couzis Alexander , Banerjee Sanjoy
Published: February 2020

Rechargeable zinc-nickel flow-assisted batteries are attractive in applications like frequency regulations, UPS inverters and hybrid electrical vehicles, etc[1] due to their advantages, such as, being cheap, capable of rapid charging and discharging and high energy density. However, the challenge that rechargeable zinc-anode batteries are facing is short lifespan time due to non-uniform morphology of zinc deposition during charging, hydrogen evolution that compromises energy efficiency and zinc corrosion during battery resting, which leads to further capacity loss[2].

We developed an indicator that monitors the transition of zinc morphology during battery charging[3]. Zincate concentration in the electrolyte, flow velocity and current density were varied over a wide range in the experiments. The results from SEM and 3D X-ray computer tomography (figure 1) show that the ratio between the effective current density and the limiting current density (current density ratio), which is directly related to the zincate concentration at the electrode surface, determines the zinc morphology. 

Furthermore, we investigated the causes of transition of zinc morphology. Compact zinc deposits are found to have a fine-grained, bright finish and the highest anodic efficiency (figure 2)[4]. Electrochemical impedance spectroscopy (EIS) proves that compact zinc corresponds to the minimum in the half-cell resistance, indicating it is kinetically preferred for compact zinc to form. Preferred crystal orientations of compact zinc depositions make good agreement with the EIS results.

Anode substrate is a parameter that also influences the zinc morphology. We studied the effects of various novel metal substrates on zinc morphology over battery cycling. Results from electrochemical techniques, chemical characterization and cell cycling showed that Cu and Bi are promising anode substrates.

In order to alleviate the corrosion rate and increase the lifespan of zinc-anode batteries, we investigated the impacts of additives on zinc morphology and cell performance. Lab-scale cells have demonstrated more than 2000 cycles and large-scale cells (113Ah) have demonstrated more than 200 cycles (figure 4 and figure 5). The results indicate that the morphologies of zinc deposition with the presence of additives are finer and the battery performance is improved as well.

References:

[1]       D.E. Turney, M. Shmukler, K. Galloway, M. Klein, Y. Ito, T. Sholklapper, J.W. Gallaway, M. Nyce, S. Banerjee, J. Power Sources 264 (2014) 49–58.

[2]       Y. Ito, M. Nyce, R. Plivelich, M. Klein, D. Steingart, S. Banerjee, J. Power Sources 196 (2011) 2340–2345.

[3]       Y. Ito, X. Wei, D. Desai, D. Steingart, S. Banerjee, J. Power Sources 211 (2012) 119–128.

[4]       D. Desai, X. Wei, D.A. Steingart, S. Banerjee, J. Power Sources 256 (2014) 145–152.

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Flexible and Stretchable Supercapacitors from Carbon Materials
Authors: Zhou Yihao , Cao Changyong , Ubnoske Stephen , Henry Philemon A. , Parker Charles B. , Franklin Aaron , Glass Jeffrey T.
Published: February 2020

Flexible and stretchable electronics have attracted increasing attention over the past decade. Compared with traditional electronics, which based on rigid silicon chips, flexible and stretchable electronics can conform to complex surfaces and sustain large deformations without sacrificing their performance. An important component of flexible or stretchable electronics is energy storage, such as supercapacitors or batteries. Existing stretchable supercapacitors are characterized by complicated fabrication processes, low stretchability and high cost, constraining their potential applications. Due to their electrical characteristics and large surface areas, carbon materials, such as activated carbon, carbon nanotubes, and graphene, have been investigated for supercapacitor applications. In this work, we report two new kinds of flexible and stretchable supercapacitors made from carbon nanotube and hybrid carbon materials using a facile and low-cost method.

Stretchable electrodes were developed using vertically aligned carbon nanotube (CNT) forests grown on a silicon substrate by PECVD. The CNT forests were transferred to a prestretched elastomer substrate using a dry-transfer method. The CNT electrodes can be biaxially stretched up to 300% while maintaining good electrochemical performance. The area specific capacitance is enhanced almost 10x to more than 20mF/cm2. CNT forests can form novel micro- and nano- patterns under uniaxial or biaxial prestrains, making it possible to use them as conductive hierarchical scaffolds for functionalization with pseudocapacitive materials, such as MnO2 for better performance.

Aerosol jet printing and self-organized origami were used to fabricate a stretchable RGO/CNT/PEDOT: PSS supercapacitor. The unique direct-printing method gives the supercapacitor outstanding mechanical properties. No delamination was observed at the interface between the printed film and the substrate during the large deformation process.  The composite electrodes exhibited highly porous structures and high conductivity, which leads to good electrochemical performance: a large specific capacitance (150F/g), high rate capability (>95% at 5A/g compared to 0.1A/g), and high cyclability. Further, there was little performance degradation after hundreds of stretch-release cycles, indicating the excellent reliability of the stretchable devices.

Our designs and methods open a new way for fabricating future energy storage devices with high deformability, high performance and low cost.
Studies of Fundamental Charge Transfer Processes in Organic Radical-Containing Polymer Films Using Spectroelectrochemical Techniques
Authors: Hughes Barbara Katherine , Braunecker Wade A. , Johnson Justin C. , Ihly Rachelle , Gennett Thomas
Published: February 2020

The electrochemical redox reaction of stable organic polymer materials with unpaired electrons is a relatively new and exciting area of battery research.  Specifically, stable nitroxyl radical-containing polymers have displayed excellent characteristics as the cathode-active material and have presented themselves as a low-cost and environmentally friendly alternative to the current Li-ion battery technologies. However, with the advancement of organic-radical battery technology there is a lack of fundamental understanding of the dynamics of charge transfer processes, electronic and ionic, within organic radical-containing polymers.  In order to elucidate these mechanisms further, we have conducted extensive spectroscopic and spectroelectrochemical investigations of macromolecular systems containing nitroxide radicals.

We have employed spectroelectrochemical experiments for our study of stable radical polymer systems whereby, kinetic information was determined, specifically rates of charge transfer and ion diffusion within our polymer systems. A key factor determining the success of such experiments is that the material of interest exhibits a strong absorption coefficient and allows for measurement in the concentration regime conducive for electrochemical studies (typically up to 10 mM).  For this reason, of the available stable nitroxyl radical systems, we have chosen first to study the oxidation of a nitronyl nitroxide derivative. To simulate an electrode architecture, spectroelectrochemical studies were performed in the solid state, and the efficacy of charge transfer was investigated as a function of film thickness, counter-ion size, and radical polymer composition in “neat” polymer films. The addition of semiconducting carbon nanotubes at various loadings was also explored as changes to film conductivity has significant implications for rates of ion transport.
Influence of Nanostructured Carbon Supports on Nanocatalysts Towards Electrooxidation of Formic Acid for Direct Formic Acid Fuel Cells
Authors: Shanta Tamanna Ferdous , Miao Wujian
Published: February 2020

Direct formic acid fuel cells (DFAFCs) have been reported as a prominent source of alternative green energy and solution to imminent energy crisis for the last two decades. The challenge to commercialize DFAFCs is mainly the utilization of cost effective, high performance and durable anodic catalyst for electrooxidation of formic acid (HCOOH). Low metal loading, high surface area, good electrical conductivity, excellent stability in acidic and alkaline media, and easy availability make nanostructured carbon supports attractive for fuel cell applications. We report here the comparative studies of three different carbon based support materials and their influence on catalytic activities towards the electrochemical oxidation of HCOOH using mono (20 wt% Pd) and ternary (10 wt% Pd-Ni-Co) composite nano-catalysts with commercial 20 wt% Pd/C (activated carbon, ~500 m2g-1). The nano-catalysts were synthesized using Pd2+, Ni2+ and Co2+ precursors using Vulcan-XC72 (250 m2g-1, <50 nm), Ketjen Black (1400 m2g-1) and graphite nano-particles (GNP) (~10 nm) support materials and NaBH4 as reducing agent. The electrochemical oxidation of HCOOH was conducted at a glassy carbon disk electrode (GCE, 3 mm diameter) pre-casted with 9 µL of each catalyst ink covered with 3 µL Nafion® polymer (5 wt%) in 0.50 M HCOOH-0.10 M H2SO4. The catalytic oxidation behavior of HCOOH of all the catalysts was compared using cyclic voltammetry. Multi-potential step chronoamperometry (CA) was utilized for stability tests. The catalytic behavior of all the ternary nano-catalysts is believed to be ascribed to the direct oxidation pathway of HCOOH as indicated by the oxidation peak potential of ~ -0.2 V vs Hg/Hg2SO4 (satd. K2SO4) reference electrode. In contrast, the synthesized mono catalysts and commercial Pd/C showed both direct and indirect oxidation pathways. The use of Ni and Co also showed synergistic effect as the HCOOH oxidation peak potential was shifted negatively by ~200 mV with respect to that of the commercial catalyst containing even doubled amounts of Pd. Furthermore, CA data showed that GNP and Ketjen Black supported catalysts were almost as stable as the commercial Pd/C, although the electrooxidation current at the Vulcan-XC72 based catalysts decreased by ~50% within about 20 min. On the other hand, Vulcan-XC72 supported catalysts showed the highest HCOOH oxidation current and the rest were in close proximity to one another. Finally, morphology and elemental analyses employing scanning electron microscope and energy dispersive X-ray spectroscopy revealed the different catalytic activity on various support materials were concordant with the electrochemical data as the turbostratic substrates contributed better metal dispersion and uniform size distribution.

Financial support from the CAREER Award (CHE-0955878) is gratefully acknowledged.
(Invited) Resolution of Carbon Nanotube Enantiomers By DNA
Authors: Zheng Ming
Published: February 2020

Single-stranded DNA (ssDNA) has been used to sort single-wall carbon nanotubes (SWCNTs) by their chiralities. The DNA-based SWCNT sorting is proposed to be based on ordered structure formation of specific DNA sequences on particular SWCNT structures. This implies that DNA-based sorting method should be able to separate nanotube enantiomers. In this work, we show that indeed single chirality (n,m) species purified by the DNA method through aqueous two-phase extraction are also highly enriched in one of the (n,m) enantiomers. We will discuss physical mechanisms behind the enantiomer resolution, and DNA sequence code for the recognition of different (n,m) species.
(Invited) Using Variance Spectroscopy to Measure Single-Walled Carbon Nanotube Absorption Cross Sections
Authors: Weisman R. Bruce , Sanchez Stephen R. , Bachilo Sergei M. , Kadria-Vili Yara , Lin Ching-Wei
Published: February 2020

A well known challenge in nanotube research is that typical SWCNT samples contain a wide range of diameters, roll-up angles, metallicities, lengths, and defect states. This structural heterogeneity leads to complex superpositions of spectral features and complicates efforts to determine fundamental and useful properties such as absorption cross sections of specific (n,m) species. We report here 11 new absolute E11 cross section values measured with our recently developed method of variance spectroscopy. This method analyzes the minor variations in fluorescence spectra captured from different small regions of dilute bulk samples. These variations reflect random changes in local compositions resulting from the limited number of nanoparticles within each probed volume. The variations among a set of ca. 2000 independent spectra are analyzed at each emission wavelength to provide spectrally resolved information, in contrast to familiar fluorescence fluctuation techniques such as FCS. This analysis let us obtain the particle concentrations of specific (n,m) species within a sample. Through combined variance and absorption analysis, we have thereby been able to determine the peak and integrated E11 absorption cross sections for the (6,4), (9,1), (8,3), (7,3), (7,5), (7,6), (10,2), (9,4), (8,6), (9,5), and (8,7) species calibrated against our previously reported (6,5) value. These measured cross sections are found to increase substantially with decreasing nanotube diameter and to be systematically larger for mod 1 than for mod 2 structures. We believe that these results will allow absolute, structure-specific SWCNT concentrations to be easily determined in basic and applied nanotube laboratories. In addition, the use of variance spectroscopy provides a promising new tool for extending such fundamental cross section measurements to additional (n,m) species.
(Invited) Organic Functionalization of Lithium-Ion-Endohedral Fullerenes
Authors: Matsuo Yutaka
Published: February 2020

Lithium-ion-containing fullerene Li+@C60 has very high electron affinity and low-lying LUMO level at -4.3 eV due to encapsulated positive charged lithium ion in the fullerene cage. Because of this property, reactivity of Li+@C60 on organic functionalization is very different from empty fullerene. In this presentation we will show the synthesis of lithium-ion-containing PCBM ([6,6]-phenyl-C61-butyric acid methyl ester) (Li+@PCBM). The [5,6]- and [6,6]-isomers of [Li+@PCBM]PF6
– were successfully prepared, and the structure of [6,6]-[Li+@PCBM]PF6
– was elucidated by X-ray crystallography. In addition, we will discuss reactivity of the Diels-Alder reaction on Li+@C60. The Diels–Alder (DA) reaction of fullerene is one of the most important reaction in the fullerene chemistry. We studied the reaction of Li+@C60 with cyclopentadiene, which were chosen as an diene, and found that this reaction was highly efficient, with an equilibrium constant that was more than 1000-fold that for the reaction with empty C60. The DA reaction of [Li+@C60](PF6
–) with 1,3-cyclohexadiene was also kinetically and computationally investigated to precisely determine the kinetic parameters. Compared with empty C60, Li+@C60 reacted 2400-fold faster at 303 K. The result was well explained by DFT calculation at the M06-2X/6-31G(d) level of theory considering the reactant complex with dispersion corrections as well as by the frontier molecular orbital theory.

Figure 1
(Invited) Aromaticity, Cage Structure, and Relative Abundancy of Endohedral Metallofullerenes
Authors: Luis Josep M , Garcia-Borràs Marc , Osuna Sílvia , Solà Miquel
Published: February 2020

The synthesis of endohedral metallofullerenes (EMFs) from a carbon soot sample of an arc discharge leads to a variety of EMFs that are obtained in different relative abundances. Several different guiding principles as the relative size of the metallic cluster respect to fullerene cage, the number of electrons that are formally transferred from the metallic cluster to the fullerene cage and electrostatic repulsion between charged five-carbon rings have been used to explain the choice of the EMF most stable cages.1 However, no single factor was capable to predict the most stable isomer for all EMFs. Our group has proposed that maximum aromaticity is the driving force that determines the most suitable hosting carbon cage for a given metallic cluster.2 The most stable anionic fullerene isomer is the one whose total aromaticity is maximized. Our results show that maximum aromaticity criterion (MARC) successfully predicts the most suitable C2n cage isomer for the endohedral metallofullerenes with carbon cages from C66 to C104. Furthermore, we have used electronic-based aromaticity measures to show that relative abundances of Sc3N-based EMFs correlate with the aromaticity measures. Our results show that, for the Sc3N-based EMFs, the most abundant EMFs are the most aromatic. This result reinforces the idea that aromaticity plays a key role in determining the stability of EMFs.

1. Garcia-Borras, M.; Osuna, S.; Luis, J. M.; Swart, M.; Sola, M. Chem-ical Society Reviews 2014, 43, 5089.

2. M. GarciaBorràs, S. Osuna, M. Swart, J.M. Luis, and M. Solà, Angew. Chem. Int. Ed. 2013, 52, 9275.

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(Invited) Graphene Nanoribbons through Directed Molecular Assembly and Stitching
Authors: Jordan Robert , Wang Yue , Khan Saeed I. , Kaner Richard B. , Rubin Yves
Published: February 2020

We have exploited a crystal engineering approach for generating polydiacetylenes (PDAs) with pendent aromatic groups, which are designed as straighforward precursors of graphene nanoribbons with narrow width. Their conversion to graphene-like structures at modest temperatures will be described, as well as the similar conversion and reaction mechanisms of model compounds for the PDAs.
The Effect of Transition Metal(Al, Co) Ions Doping in α-MnO2 Materials As the Rechargeable Zinc Ion Battery
Authors: Jo Jae Hyeon , Myung Seung-Taek
Published: February 2020

Lithium-ion batteries (LIBs) have been drawn significant attention as energy storage devices with high energy density and high power. However, nowadays, the attention of many researchers has been focused on exploration of new battery systems. The promising battery systems are sodium ion battery, all-solid state battery, zinc ion battery and so on. In this study, we report a zinc ion battery system which uses MnO2 materials as the cathode, because zinc metal have advantages such as natural abundancy, safety, un-poisonous, low cost and easy handling in open air. Also, manganese dioxide (MnO2) has been widely investigated as electrode materials owing to high natural abundance, low cost and non-toxicity. This MnO2 appears in various crystallographic polymorphs such as α-, β-, γ-, δ-, and ε-MnO2. Among these materials, α-MnO2 is comprised of the basic MnO6 octahedral units which are linked through edges and/or corners to forms crystallographic structures that correspond to different type of polymorphs. However, α-MnO2/Zn ion battery has drawbacks such as the formation of by-product, poor electric conductivity and capacity retention during cycling. To improve the some properties, we conducted the doping of Al, Co ion in the α-MnO2 structure and we anticipate that the doped transition metal Al and Co ions would affect not only electrochemical property but also structural stabilization. Therefore, we report on the effect of transition metal (Al, Co) doping in α-MnO2 materials on structure and electrochemistry.

 The Al∙Co-α-MnO2 nanorods was synthesized via hydrothermal method and the Al and Co source was added in molar ratios (5%, 15%, and 25%) to obtain Al∙ Co-α-MnO2 with various doping levels. The crystalline phase of the synthesized products was characterized by powder XRD using Cu-Kα radiation. Using these XRD data, lattice parameters were performed to identify the variation of a-,c- axis and volume. Also, ICP-AES was carried to measure the amount of Al and Co ion in the MnO2 structure. Also, SEM and TEM were employed to observe the surface and morphology of particle. The electrochemical tests were performed in coin type zinc cell. The used electrolyte solution was 1 M ZnSO4 (pH 4.0). The coin cells were charged and discharged between 1.0 and 1.8 V at room temperature.

The XRD patterns of bare α-MnO2 and doped α-MnO2 obvious appeared single phase with I4/m space group and the XRD data of the Al, Co-doped α-MnO2 exhibited peak shift. The result of lattice parameter appeared change in values of a-, c-axis and volume. According to ICP-AES results, we could identify the amount of doped Al and Co ions. The electrochemical performances of the bare and Al, Co doped MnO2 electrode were tested in the voltage range of 1.0 – 1.8 V. Details will be discussed in the conference site.

Figure 1
Characterization of Carbon Materials for Redox Flow Battery Electrodes By Potential-Step Coulometry
Authors: Sato Yukari , Narita Ayumi , Kaneko Yuji , Negishi Akira , Nozaki Ken , Kato Tohru
Published: February 2020

Redox-flow batteries, which are using organic compounds, aqueous solution, and new Ti/Mn redox systems, have been actively investigated [1,2,3]. Non-metal redox-flow batteries are strongly expected by the increasing in needs for low-cost, safe, and trusted energy storage applications. Both of redox active materials and cell systems of redox-flow batteries have made rapid and great progress in recent years. Redox-flow batteries are investigated frequently, and are now in a transition stage.

We evaluated the electrode performance of three different kind of carbon electrode materials with vanadium electrolyte solution by using potential-step coulometry measurement. Different kind of electrolyte solutions were also evaluated with similar system.

Figure 1 showed model of the half cell. In this experiment, electrolyte solution was stopped and charging and discharging current and coulomb number were measured. Figure 2 showed results of the voltage-step coulometry for two typical carbon electrodes (set voltages are 1.50 V for charging and 0.80 V for discharging). Electrochemical property of cathode and anode electrodes are also investigated individually.

References:

[1] B. Huskinson, M. P. Marshak, C. Suh, S. Er, M. R. Gerhardt, C. J. Galvin, X. Chen, A. Aspuru-Guzik, R. G. Gordon and M. J. Aziz, Nature, 505, 195 (2014).

[2] Y. -R. Dong, H. Kaku, K. Hanafusa, K. Moriuchi, and T. Shigematsu, ECS Trans., 69 (18), 59 (2015)

[3] S.-E. Chun, B. Evanko, X. Wang, D. Vonlanthen, X. Ji, G. D. Stucky and S. W. Boettcher, Nature Communications
6, 7818 (2015).

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The Influence of Flow Field and Electrode Design on Crossover of Ions in All-Vanadium Redox Flow Batteries
Authors: Ashraf Gandomi Yasser , Houser Jacob , Aaron Douglas , Mench Matthew M.
Published: February 2020

Among the many types of redox flow batteries (RFBs), the all-vanadium redox flow battery (VRFB) is one of the most viable chemistries for commercialization 1. One of the key factors obstructing the commercialization process of VRFBs is the high cost of these systems, resulting from relatively poor performance 2. Flow field and electrode design are considered to be key optimization factors in VRFBs that can enable high battery performance and resultant market competitiveness 3. The flow field and electrode designs are known to directly affect the mass transport, performance, capacity utilization, and parasitic pressure losses 4. Much experimental and modeling work has been done to understand the combined effect of flow field design and electrodes on mass transport behavior and performance of VRFBs 5 and other electrochemical systems 6. However, neither modeling nor experimental approaches targeting the direct effect of flow fields and electrodes on vanadium crossover has been reported.

In this work, we will present experimental data in which different flow fields, along with different electrode materials, have been tested from multiple perspectives including overall cell performance, pressure drop and vanadium crossover. A UV-Vis spectroscopy setup has been implemented to quantify vanadium crossover under different operating conditions. The results of this study should provide more in-depth insight to optimize VRFBs for enhanced performance and reduced vanadium crossover and pressure drop.

Fig.1 : The effect of the different flow plate design on the VRFB systems

(a) Performance

(b) Image of the solution at the end of experiment for different cell configurations

References:

1. M. Skyllas-Kazacos, M. Chakrabarti, S. Hajimolana, F. Mjalli, and M. Saleem, Journal of the Electrochemical Society, 158 (8), R55-R79 (2011).

2. D.S. Aaron, Q. Liu, Z. Tang, G.M. Grim, A.B. Papandrew, A. Turhan, T.A. Zawodzinski, M.M. Mench, Journal of Power Sources, 206 450-453 (2012).

3- J. Houser, J. Clement, A. Pezeshki, and M. M. Mench, Journal of Power Sources, 302 369-377 (2016).

4. Y. A. Gandomi, T. A. Zawodzinski, and M. M. Mench, ECS Transactions, 61 (13), 23-32 (2014).

5. Y. A. Gandomi, D. Aaron, T. Zawodzinski, and M. Mench, Journal of The Electrochemical Society, 163 (1), A5188-A5201 (2016).

6. Y. A. Gandomi and M. M. Mench, ECS Transactions, 58 (1), 1375-1382 (2013).

Figure 1
Pre-Treated Carbide-Derived Carbon for Enhanced Electrode Performance
Authors: Yeon Sun-Hwa , Lee Sang-Ho , Kim Dong-Ha , Park Se-Kook , Shin Kyoung-Hee , Jin Chang-Soo
Published: February 2020

Various kinds of carbonaceous materials have been extensively studied for use as the electrodes in energy storage devices for transportation and renewable energy storage applications. Capacitive electrodes (CEs) are used in a broad range of systems related to both energy and water infrastructures across the globe. Carbide-derived Carbon (CDC), a suitable carbon material for supercapacitor applications, has been presented due to its simple preparation and easy control of structures and properties such as graphitization and porosity. CDCs produced by binary and ternary carbides showed significantly improved electrochemical capacity as various electrodes for supercapacitor and lithium ion battery.

In this work, we demonstrate significantly improved electrochemical capacitance of a CDC by controlling pore texture and crystallization through the introduction of pre-treatment at high temperature for supercapacitor application. By tailoring the pore texture and graphitic structure of CDCs as pre-vacuum treatment from carbide, the electrode showed a high increase of capacitance under wide range of various scan rates from 2 mV/s ~ 100 mV/s.
A Flame Spray Process for Cathode Materials Manufacturing for Lithium Ion Batteries
Authors: Liao Jinyun , Rana Jatinkumar , Hamad Khaleel , Smith Taylor , Xing Yangchuan
Published: February 2020

The EV Everywhere Blueprint of DOE has a goal to cut lithium ion battery costs from their current $500/kWh to $125/kWh. This 75% reduction can only be achieved with an array of technological innovations and process integrations. One major factor in the battery cost is the positive electrode, which is made of complex metal oxide powders, such as Li(Ni1/3Mn1/3Co1/3)O2. Therefore, reducing the cathode materials cost has been a major effort in the battery cost reduction endeavor.

Flame (combustion) processes are the most economic ones to produce fine powders and have been used to produce pigment titanium oxide and fused silica in large volumes. In this work a flame spray pyrolysis (FSP) process has been developed to make metal oxide powders for the positive electrode materials at low cost. In particular, the work was focused on making metal oxides of NMC materials with stoichiometric compositions and desired morphologies, as shown in Fig. 1. Our FSP is a green chemical process employing low cost biomass precursors for the battery material manufacturing. The detailed results of the synthesis, characterization, and battery testing of the NMC powder materials will be presented.

Fig. 1. Produced NMC powder from the FSP process and its elemental distribution of Ni, Mn, and Co uniformly distributed throughout the powder.

Figure 1
(Invited) Understanding the Role of Al3+ in Accelerated Testing and Its Impact on the Protective Oxide Film of AA2060
Authors: Kelly Robert G. , Parker Mary Elizabeth
Published: February 2020

In accelerated corrosion testing of aluminum-alloys, the stability of the protective oxide layer has a significant impact on corrosion rate and morphology. Many times the oxide layer is intentionally weakened during accelerated tests. An acidic solution pH can increase the general corrosion rate by uniformly thinning the oxide film, and a high chloride concentration can increase localized corrosion rates. Recent work has suggested that other chemical species may also impact the oxide film of aluminum during accelerated testing.

In this study, aluminum-lithium alloy 2060 was tested in solutions of 1 M sodium chloride (NaCl) and 0.1 M potassium sulfate (K2S2O8) with and without the addition of a small amount (0.022 M) of aluminum chloride (AlCl3). The K2S2O8 was an oxidizing agent added to provide a fast cathodic reaction during corrosion. It was found that even a small amount of Al3+ could dramatically increase the frequency of attack for AA2060 as shown in Figure 1. Linear polarization was used to compare electrochemical kinetics with and without added Al3+, and samples that were tested with 0.022 M AlCl3 had a significantly higher diffusion limiting current (ilim) and consequently, a higher corrosion rate. For the near peak-aged AA2060-T86 temper, ilim was twenty-eight times higher with 0.022 M AlCl3 than without. The impact on the under-aged AA2060-T36 temper was smaller, but still significant at over three times higher ilim with added Al3+. The concentration of oxidizing agent was the same in tests with and without added Al3+, so these results suggest that the increase in i­lim may be due to increased diffusion through the protective oxide film. To further investigate this phenomenon, electrochemical impedance measurements will be used to study the oxide film of AA2060 in solution with and without added Al3+.

Figure 1