bluuebunny/crossref_metadata_2025 huggingface dataset:
Cylindrical Graphene Nanomaterials for Disease Assessment and Drug Development
Authors: Heller Daniel A , Budhathoki-Uprety Januka , Frederiksen Rune , Galassi Thomas Vito , Harvey Jackson Dean , Horoszko Christopher Peter , Jena Prakrit Vaibhav , Langenbacher Rachel E , Roxbury Daniel , Shah Janki , Shamay Yosef , Williams Ryan M.
Published: February 2020

The real-time and spatially-resolved detection and identification of analytes present important goals for next-generation nanoscale sensors. Low-dimensional nanomaterials may improve the detection of molecular binding phenomena and result in better quantification of disease biomarkers and other bioanalytes. Cylindrical graphene provides a non-degradable, luminescent material for bioanalytical measurements which exhibits minimal toxicity. We developed hybrid polymer and biopolymer/cylindrical graphene nanomaterials to quantify bioanalytes in live cells, tissues, and organisms for studies in disease biology and for assays to facilitate drug development.
(Invited) Tungsten-Based Intermetallic Compound As Catalyst for Structure-Specific Growth of Single-Walled Carbon Nanotubes
Authors: Li Yan , Yang Feng
Published: February 2020

Different from the conventional mono-metal catalysts, tungsten-cobalt intermetallic compound W6Co7, which belongs to monoclinic crystal system, presents lower structural symmetry and a very unique atomic arrangement. Therefore, W6Co7 exhibits specific geometry match towards the end structures of single-walled carbon nanotubes (SWNTs). This kind of one-by-one recognition between a crystal plane to a certain chirality of SWNTs enables this tungsten-based intermetallic compound an efficient template for structure-specified growth of SWNTs. This idea was revealed by both DFT simulation and the result of chemical vapor deposition growth of SWNTs. The manipulation of the structures of the W6Co7 catalysts was also performed to meet the requirements of the selective growth of SWNTs with different chiralities.
Displacement Kinetics of Single-Stranded DNA Wrapped Around Carbon Nanotubes
Authors: Zheng Yu , Bachilo Sergei M. , Sanchez Stephen R. , Weisman R. Bruce
Published: February 2020

Surface coatings on single-walled carbon nanotubes (SWCNTs) play key roles in their properties and applications. One of the most intriguing coatings is single-stranded DNA, which is known to helically wrap individual nanotubes with affinities that depend on oligonucleotide sequence and SWCNT structure. To better understand such selective interactions, we use fluorescence spectroscopy to monitor the kinetics of ssDNA displacement by sodium deoxycholate (SDC), a common surfactant. This displacement causes distinct changes in the wavelength and intensity of structure-specific SWCNT near-IR emission peaks. By quantifying the kinetics of these changes as a function of oligonucleotide sequence, oligonucleotide length, SWCNT structure, sample temperature, and SDC concentration, we have extracted sets of values for the activation enthalpy ∆H≠, activation entropy ∆S≠, and activation Gibbs free energy ∆G≠ for displacement of d(GT)
n
, with n ranging from 15 to 30. We find that rates of displacement decrease for longer oligonucleotides and drop sharply as nanotube diameter increases from 0.75 to 0.97 nm. These increases in ∆G≠ are attributed to increases in -T∆S≠ that exceed the decreases in ∆H≠ over this range. Remarkably, the kinetics also reveal a strong power-law dependence (up to 6th order) in SDC concentration, indicating a highly cooperative process for ssDNA displacement. We will present experimental results and a proposed mechanistic interpretation.
(Invited) Modification and Analysis of Carbon Based Structures By Metal Nanoparticulate Ions
Authors: Schultz John Albert , Hauge Robert , Adams W. Wade , Brinson Bruce E , Kim Nam Dong , McCully Michael , Lewis Ernest , Barbacci Damon , Balaban Carey , Muller Ludovic , Jackson Shelley , Woods Amina
Published: February 2020

Our collaborative work to create and soft land ionized gas phase single crystalline metal nanoparticulate ions onto substrates was motivated by Robert Hauge’s wish to produce templates for carbon nanotube carpet growth. Ionwerks created a machine to do this but, as is often the case, funding was found first for alternative applications.

One such has been low energy (500 eV) injection of 8 nm silver nanoparticulate ions (AgNP-) into the near surface of bio-polymers. A uniform layer (70 e15 Ag atoms/cm2) of these implanted particles serve to assist the laser desorption of intact biomolecules from a brain tissue sample into the gas phase. Some of these desorbed molecules are ionized and can be transported into a mass spectrometer and uniquely identified by their exact mass to charge (m/z). By scanning a 50 micron focused laser across the surface of an AgNP implanted rat brain tissue sections, a complete mass spectrum can be acquired at each of several hundred thousand laser locations. Images of specific biomolecules can be derived from these spectra. Putative molecular biomarkers can then be identified by inter-comparing the numerous molecular images from each animal grouping within an animal study. Images from the same brain levels between injured (or diseased) and uninjured rats define histological micro domains in which elevated or decreased molecular ion intensities correlate with other measures of injury/disease state severity. Imaging of these biomarker ions is becoming useful in preclinical screening of drug candidates and should ultimately enter clinical settings.

The AgNP enhanced mass spectral imaging has been also applied to the surface analysis of synthetic polymers, fullerenes, and nanotubes.

A third application uses 30 keV, 15 nm AgNP ion impacts to form otherwise unattainable controlled nano-sized holes in graphene—especially “rebar” graphene. Alternatively, low energy soft landing at lower energy can form nanostructures upon the graphene which have implications for device formation.

However, before departure, Bob made it clear that we needed to get back to carpet growth and other ideas which he outlined in extensive and explicit discussions—mostly at outdoor cafes and coffee shops. His dictates and imprimatur remain.
(Invited) Functionalization and Environmental Dependent Emission Properties of Photoluminescent Defect States in Carbon Nanotubes
Authors: Doorn Stephen K. , He Xiaowei , Hartmann Nicolai F. , Gifford Brendan , Tretiak Sergei , Htoon Han , Bullad George , Olivier Jean-Hubert , Therien Michael J.
Published: February 2020

Red-shifted emitting states in carbon nanotubes, introduced by chemically stable and tunable covalently-bound dopants,1,2 are gaining attention for their potential to boost photoluminescence quantum yields,1,2 add new functionality,3,4 and serve as single photon emitters.5 These sites present a rich array of new photophysics, with dependences on specific functionalization chemistry and environmental interactions. As examples, we will present low-T photoluminescence (PL) probes of defect-state electronic structure for sp
3 defects introduced by aryl functionalization and compare to quantum chemical theory and to earlier studies on oxygen-introduced defects.6 Environmental effects on both low-T spectroscopy and ensemble-level relaxation dynamics7 will also be presented. In particular, dielectric environment is found to significantly impact PL relaxation times in contrasting ways, enabling further understanding of relaxation mechanisms and how they relate to spectroscopic observables. Finally, control over chemical functionality and dielectric environment will be shown as routes for optimizing single photon emission behaviors, in agreement with earlier theoretical results.8

References

1. Ghosh, S. et al., Science, 330, 1656 (2010).

2. Piao, Y. et al., Nature Chem., 5, 840 (2013).

3. Kwon, H. et al., J. Phys. Chem. C, 119, 3733 (2015).

4. Akizuki, N. et al., Nature Comm., 6, 8920 (2015).

5. Ma, X. et al., Nature Nanotech., 10, 671 (2015).

6. Ma, X. et al., ACS Nano, 8, 10782 (2014).

7. Hartmann, N. et al., ACS Nano, 10, 8355 (2016).

8. Hartmann, N. et al., Nanoscale, 7, 20521 (2015).
(Invited) Electronic Measurements of Single- and Multi-Walled Carbon Nanotubes: Evidence for Unusual Behavior at Nanotube-Nanotube Junctions
Authors: Barron Andrew R , Barnett Chris , Gowenlock Cathren
Published: February 2020

The use of a UHV nanoprobe allows for simultaneous electrical measurements of individual and bundles of carbon nanotubes while performing STM, SEM and Auger. The Four probe tips can be accurately positioned on to a one-dimensional nanostructure such as a nanotube to perform measurements of resistivity and electrical transport properties at low temperatures, while their exact position can be determined. Multi-walled carbon nanotubes (MWNTs) and single-walled carbon nanotubes (SWNTs) have been investigated. In particular, the effects of conductivity as a function of the presence or absence of a junction have been investigated. The effects of probe pressure and thermal annealing have been measured, as has the application of pressure to the nanotube. For MWNTs a resistance per unit distance of 4 kΩ/μm has been determined that matches theoretical models. Interestingly, resistance is independent of path at a MWCNT-MWCNT junction; however, there is a 100x increase in resistance at the point of the junction.
Synthesis of Carbon Nanostructures over Catalytically Active Nanoporous Gold and Cu Foams
Authors: Dervishi Enkeleda , Tappan Bryce , Boncher William L
Published: February 2020

Although nanoporous gold has been shown to be a promising catalytic material, few methods for preparing monolithic nanoporous Au foams, especially of metallically pure Au, exist. Here we present combustion synthesis of ultralow density, metallically pure gold nanofoams with bulk densities of less than 0.1 g/cm3 and surface areas as high as 10.9 m2/g. To our knowledge, these nanofoams represent one of the lowest density and highest surface area coherent forms of gold produced to date. The nanofoams were found to be highly catalytically active towards chemical vapor deposition synthesis of carbon nanotubes. For the first time, we report the growth of carbon nanotubes on Au nanoporous foams utilizing methane as the hydrocarbon source and demonstrating a novel method for a direct nanotube synthesis on conductive substrates. We found that by varying the synthesis conditions (hydrocarbon source and concentration), we were able to synthesize various 1D and 2D nanomaterials. Interestingly, Cu foams were found to be catalytically inactive in generation of any graphitic structures, under the same synthesis conditions as Au foams. We can tune and modify the morphological properties of the nanofoams, to generate graphitic nanostructures with specific electrical and mechanical properties.
Optical Properties of a-Sexithiophene Dyes Aggregated inside Carbon and Boron Nitride Nanotubes
Authors: Gaufres Etienne , Allard Charlotte , Tang Nathalie , Fossard Frederic , Schué Leonard , Barjon Julien , Martel Richard , Loiseau Annick
Published: February 2020

The inner cavity of nanotubes attracted a lot of interest as template for the encapsulation of elongated dyes molecules, such as polythiophenes. Indeed, the 1D confinement drives the stacking of the molecules inside and enables original aggregation effects on their optical properties (1,2). When encapsulated inside carbon nanotube, the 6T exhibits for example a strong and specific Raman scattering but its luminescence is efficiently quenched by the nanotube (3). Here we show that the same dye, when encapsulated inside boron nitride (6T@BNNT) exhibits strong luminescence with signature of inter-molecules coupling (4). Photoluminescence imaging experiments on individualized 6T@BNNT deposited on substrate show that the encapsulation also prevents the bleaching of the molecules under strong photoexcitation, harsh oxidizing exposure and annealing in air up to 350°C.

(1) E. Gaufrès et al Nature Photon. (2014)

(2) S. Cambré et al Nature Nano. (2015)

(3) E. Gaufrès et al ACS Nano (2016)

(4) E. Gaufrès et al (submitted)
Variance Spectroscopy Monitors the Sonication-Induced Cutting and Debundling of Single-Walled Carbon Nanotubes
Authors: Sanchez Stephen R. , Bachilo Sergei M. , Zheng Yu , Streit Jason K. , Weisman R. Bruce
Published: February 2020

It is well known that ultrasonic processing is a crucial step for preparing suspensions of individualized single-walled carbon nanotubes (SWCNTs). Sonication disaggregates nanotube bundles but can also cut long nanotubes into shorter segments and introduce defect sites that degrade optical properties. To study these processes in detail, we have applied the newly developed method of variance spectroscopy.1 In this technique, we analyze fluorescence spectra from many different small regions of a dilute SWCNT sample to determine the variations in emission brought about by statistical changes in composition. By analyzing the first and second moments of the intensity distributions at each wavelength, we construct the mean and variance spectra. Simple analysis of these spectra then reveals the number of particles per unit volume of different (n,m) species present within the mixed sample and the average emission per particle for various (n,m) species. Deeper data analysis gives covariance plots, showing aggregation between different species, and third moment (skew) spectra, showing aggregation of individual species.

Starting with a sample of relatively long SWCNTs that had been dispersed in surfactant solution by high shear mixing, we measured variance spectra as a function of sonication time and power. We found that the number density values for every (n,m) species increased with sonication time, reflecting initial further disaggregation and a slower cutting process. These rates of number density increase showed no apparent dependence on nanotube diameter or chiral angle. To confirm the changes in SWCNT length caused by cutting, we also measured full length distributions using the diffusion-based LAND method.2 Findings from these length distributions were compared to the change in number density values in order to disentangle the effects of debundling and cutting. We believe that this is the first study to separately observe these effects. Damage to SWCNTs during continued sonication was monitored through decreases in the values of emission per particle, as determined from variance spectra. We also introduce here the use of skew analysis to obtain a quantitative index of self-aggregation. The experimental results will be compared to findings from a numerical model constructed to represent the main processes occurring during sonication. Our study should allow the optimized preparation of SWCNT dispersions.

1. J. K. Streit, S. M. Bachilo, S. R. Sanchez, C.-W. Lin, and R. B. Weisman, J. Phys. Chem. Lett., 3976-3981 (2015).

2. J. K. Streit, S. M. Bachilo, A. V. Naumov, C. Khripin, M. Zheng, and R. B. Weisman, ACS Nano,
6 (9), 8424-8431 (2012).
(Invited) Waveguide Integrated Electrically Driven Carbon Nanotube Light Sources
Authors: Krupke Ralph
Published: February 2020

I will report on our recent success in fabricating waveguide-integrated carbon nanotube light sources with superconducting single photon detectors. This complete quantum photonic circuit allows for on-chip correlation experiments to explore non-classical light emission. I will furthermore explain how the photonic environment can be used to tailor the emission wavelength and linewidth of a nanotube emitter and the feasibility of carbon nanotube transducers for fast signal processing.

[1] F. Pyatkov et al., Nature Photonics 10 (2016), pp. 420.

[2] S. Khasminskaya et al., Nature Photonics 10 (2016), pp. 727.

Figure 1
(Invited) Non-Markovian Decoherence and Purcell Effect: How to Enlarge the Bandwidth of a Carbon Nanotube Based Single-Photon Source
Authors: Jeantet Adrien , Chassagneux Yannick , Lauret Jean-Sébastien , Claude Théo , Reichel Jakob , Voisin Christophe
Published: February 2020

Carbon nanotubes have recently proven to be promising nano-emitters for future single-photon sources in the telecom wavelengths [1,2,3]. Coupling the nanotube to a micro-cavity brings a invaluable handle to control single-photon emission, regarding the rate, the yield, the directionnality and the extraction. All those features are related to the so-called Purcell effect that results from the interaction of a quasi-two-level system with a high Q and low mode-volume optical cavity. In carbon nanotubes though, the situation is slightly more complex due to the intimate coupling of the excitonic levels with the acoustic phonon bath, resulting in the well-known phonon wings [4]. This additional degree of freedom brings a very rich physics that can be exploited to enlarge the bandwidth of the source in view of multiplexing. A consequence of the non-Markovian decoherence induced by the phonon bath is the asymetry between the phonon-assisted absorption and emission processes. Using those transitions in the Purcell regime can lead to an enhanced single-photon efficiency above the standard limit imposed by the emitter and cavity intrinsic losses. We developped a widely tunable cavity technique, based on laser-engineered optical fibers to investigate this effect. We measure the single-photon emission properties both in the cw and time-resolved modes and explain the strong asymetry of the efficiency with respect to the detuning.

[1] A. Jeantet et al., Phys. Rev. Lett. 116, 247402 (2016)

[2] S. Khasminskaya et al., Nat. Phot. 10, 727 (2016)

[3] X. Ma, et al., Nat. Mat. 10, 671 (2015)

[4] F. Vialla et al., Phys. Rev. Lett. 113, 057402 (2013)
(Invited) Sensitizing Carbon Nanotube Transistors for Single Molecule Sensor Applications
Authors: Collins Philip G.
Published: February 2020

Recent work has demonstrated single-electron sensitivity in carbon nanotube transistors under a variety of conditions, including room temperature. In noncovalent cases like charged adsorbates or SiO2 imperfections, two-level fluctuators near the nanotube perturb the current electrostatically. In other cases, a sidewall defect or other covalent modification directly on the nanotube sidewall sensitizes a particular site. Comparative research has helped reveal differences in the transduction mechanisms of the two cases and provides design rules for maximizing reliable signals for electronic sensing. For example, noncovalent sensitization generally produces a smaller signal amplitude in a background of low-energy fluctuators at varying distances from the nanotube. Covalent modifications are far more sensitive than noncovalent perturbations, but the new degrees of freedom that accompany covalent disorder often have energy scales similar to the signal of interest, leading to multiple independent fluctuations that degrade the overall signal-to-noise for sensing. An outstanding compromise involves short, noncovalent linkers, which can produce highly predictable signal amplitudes without degradation of the device characteristics. Furthermore, noncovalent fabrication methods are scalable, so that wafer-scale arrays of molecular sensors are most likely to follow this path.
Study of Transport in a Novel, Heteropoly Acid Hybrid Polymer Membrane Designed for Use in Flow Batteries
Authors: Motz Andrew R , Kuo Mei-Chen , Kusoglu Ahmet , Tucker Michael C , Weber Adam Z. , Haugen Gregory M , Herring Andrew M
Published: February 2020

The energy storage and power density are decoupled for flow batteries, therefore they may be tailored to specific applications and offer promising potential for grid scale energy storage.1 For this new technology to make an impact on our energy landscape, cost must be reduced. Some suggested design criteria for the separator to reduce capital costs requirements an area specific resistance <0.3 ohm/cm2 and low parasitic crossover.2One mechanism of parasitic crossover is through diffusion within extensive water channels, a drawback to perfluorinated sulfonic acids. This research works at minimizing unwanted crossover through reduction of water channels. The approach taken is to use heteropoly acid (HPA) to crosslink a fluoroelastomer. When films are crosslinked, they are more restricted and less able to swell, thus reducing the channels for crossover to occur. The reason for using HPA it is has proven to have great conductivity with low water content.3

 We will report on transport of a verity of species in different electrolyte environments and discuss how film synthesis and processing can lead to more selective separators with better power and selectivity than Nafion.

References

[1] Perry, M. L.; Weber, A. Z., Advanced Redox-Flow Batteries: A Perspective. Journal of The Electrochemical Society
2015, 163, A5064-A5067.

[2] Darling, R.; Gallagher, K.; Xie, W.; Su, L.; Brushett, F., Transport Property Requirements for Flow Battery Separators. Journal of The Electrochemical Society
2015, 163, A5029-A5040.

[3] Horan, J. L.; Lingutla, A.; Ren, H.; Kuo, M. C.; Sachdeva, S.; Yang, Y.; Seifert, S.; Greenlee, L. F.; Yandrasits, M. A.; Hamrock, S. J.; Frey, M. H.; Herring, A. M., Fast Proton Conduction Facilitated by Minimum Water in a Series of Divinylsilyl-11-silicotungstic. Acid-co-Butyl Acrylate-co-Hexanediol Diacrylate Polymers. Journal of Physical Chemistry C
2014, 118, 135-144.
Development of a Li-Ion Electrochemical Platform for in-Situ TEM of Solid State Electrode/Electrolyte Interfaces
Authors: Wang Ruocun , Daubert James S. , Ning Mingqiang , Yang Yuan , Liu Yang , Parsons Gregory N. , Dickey Elizabeth C. , Augustyn Veronica
Published: February 2020

The interface of electrode materials in contact with solid-state electrolytes is of current interest for the development of devices with high energy density and good safety. In-situ transmission electron microscopy (TEM) of energy storage materials allows for the detailed study of structure-property relationships near solid interfaces during electrochemical charge and discharge. Here, we will describe the design of an in-situ TEM platform to investigate the structure-property relationship of a model energy storage oxide, V2O5, in contact with a state-of-the-art solid-state electrolyte Li7La3Zr2O12 (LLZO). The cell was fabricated by the atomic layer deposition (ALD) of V2O5 (~ 50 nm thick) onto the electrolyte and subsequent focused ion beam (FIB) milling and lift-out of a micron-long electrode/electrolyte architecture. The lithium metal anode was electrochemically deposited directly onto the gold electrode of an in-situ TEM chip. Assembly of the electrochemical cell was performed in a scanning electron microscope using a micromanipulator. Bright-field TEM and electron energy loss spectroscopy (EELS) showed that the deposited V2O5 layer formed a well-defined interface with LLZO and this allowed for the determination of the vanadium oxidation state. This work demonstrates the fabrication of a platform for the in-situ TEM study of materials at electrode/solid-state electrolyte interfaces that can readily be adapted to other types of solid state battery chemistries.
Three-Dimensional Holey-Graphene/Niobia Composite Architectures for Ultrahigh-Rate Energy Storage
Authors: Sun Hongtao , Dunn Bruce S. , Huang Yu , Duan Xiangfeng
Published: February 2020

Nanostructured electrode materials have shown considerable promise for electrochemical energy storage with ultrahigh energy density or powder density. However, such performance was often achieved in electrodes with rather low mass loading (e.g., ~1 mg cm-2 or less), which cannot be readily scaled to electrodes having practical levels of mass loading (e.g., > 10 mg cm-2) due to ion diffusion limitations in thicker electrodes. As a result, the scaled areal capacity or current density of these nanostructured electrodes rarely exceeds those of today’s Li-ion batteries. To sustain the same gravimetric capacity and current density in thicker electrodes with 10 times greater mass loading (e.g., 10 vs. 1 mg cm-2) requires to deliver 10 times more charges over 10 times longer distance, which represents a fundamental scientific challenge in electrode architecture design rather than a simple engineering scaling matter. Herein we report the design of a three-dimensional (3D) holey-graphene/niobia (Nb2O5) composite for ultrahigh-rate energy storage at practical levels of mass loading (>10 mg cm-2). The highly interconnected graphene network in the 3D architecture provides excellent electron transport properties, while its hierarchical porous structure facilitates rapid ion transport. By systematically tailoring the porosity in the holey graphene backbone, charge transport in the composite architecture is optimized to deliver high areal capacity and high-rate capability at high mass loading, which represents a critical step forward towards practical applications.
Optimizing the Design of Redox Flow Battery Electrodes Using Impedance Measurements
Authors: Murali Advaith , Yang Bo , Narayanan S. R.
Published: February 2020

The reactions in redox flow batteries are not usually limited by electron transfer. Hence, the power density and efficiency are largely determined by mass transport and ohmic limitations. Consequently, electrode structure and flow field designs are important in optimizing efficiency. Therefore, assessment of various types of flow fields in combination with porous electrodes has been the subject of simulations and analysis by several developers of redox flow batteries. [1-3] The studies show the impact of flow field design on cell performance, simulated effects of channel design, and pressure drops across the electrode when used in combination with porous carbon paper. These studies highlight the importance of such analysis for the development of the redox flow batteries as a viable energy storage solution. Our focus on improving the performance of the aqueous organic redox flow battery has led us to qualify modified graphite felt structures in combination with flow-through, interdigitated flow fields and columnar flow fields. To this end, we have characterized the cell performance using highly reversible redox couples such as ferrocyanide/ferricyanide. Specifically, the measurements include the current-voltage curves under potentiostatic conditions at various flow rates to determine the limiting current, and electrochemical impedance spectroscopy over the range of 10 mHz to 10 kHz to determine mass transport parameters and surface area of the electrode.

We have observed that the flow-through flow field configuration exhibited the lowest mass-transport resistance, highest limiting current, and the lowest electrical contact resistance with the electrode (Figure 1). However, the flow-through designs entail high pressure drop across the electrode compared to the columnar and interdigitated designs. For a given electrode structure, the diffusion layer thickness at the surface of the electrode was dependent on the flow configurations. The porosity and surface area of the electrode structures was modified by incorporation of nano-structured carbon coatings. An optimal design combines an electrode with the highest available surface area, low pressure drop, and minimal diffusion layer thickness. The rational design of such an optimal combination of electrode and flow properties is rendered possible by the measurements and mathematical analysis carried out in this study.

Acknowledgement

The Authors acknowledge the financial support for this research from ARPA-E Open-FOA program (DE-AR0000337), the University of Southern California, and the Loker Hydrocarbon Research Institute.

1. C. R. Dennison, E. Agar, B. Akuzum, and E. C. Kumbur, J. Electrochem. Soc. , 163, A5163–A5169 (2016) http://jes.ecsdl.org/content/163/1/A5163.abstract.

2. M. Skyllas-Kazacos, M. H. Chakrabarti, S. a. Hajimolana, F. S. Mjalli, and M. Saleem, J. Electrochem. Soc., 158, R55 (2011) http://jes.ecsdl.org/cgi/doi/10.1149/1.3599565.

3. C. Yin, Y. Gao, S. Guo, and H. Tang, Energy, 74, 886–895 (2014).

Figure 1
2D Electrode Materials for Energy Storage
Authors: Yan Qingyu
Published: February 2020

Li ion/Na batteries has shown great promises in various energy related applications. The performance of these energy storage devices can improved with strategized design and preparation of the electrode materials. We carried out works on growth of 2D structured cathode/anode material, including LiMPO4 (M=Fe, Ni, Co, Mn) and MPO4, and few layered black phosphorus by wet chemical processes. This type of materials is typical thin sheet structure with thickness of 2-5 nm and show promising Li/Na storage properties. For Olivine-type LiMPO4 (M = Fe, Mn, Co, Ni), we develop a liquid-phase exfoliation approach combined with solvothermal lithiation process in high-pressure high-temperature (HPHT) supercritical fluids for the fabrication of ultrathin LiMPO4 nanosheets (thickness: 3.7-4.6 nm) with exposed (010) surface facets. The diffusion of Li along [010] direction is particularly tuned through the thickness of the nanosheet due to the crystal orientation, which fasten the diffusion process. [1] For MPO4, we prepared ultra-thin two-dimensional (2D) nanoflakes, including FePO4, Mn3(PO4)2 and Co3(PO4)2, with highly ordered mesoporous structures in non-polar solvent. It is found that the as-obtained nanoflakes with thickness of ~3.7 nm are constructed from a single layer of parallel-packed pore channels. When tested as cathodes for lithium ion battery, they exhibits excellent stability and high rate capabilities. [2]. We also synthesis of few layered black phosphorus nanosheets through diferent methods and study their Li/Na storage properties. Especially, we try to improve their chemical stability by forming composite structures with the aid of spark plasma sintering (SPS) process. It shows that excellent air stabilityof SPS-processed black phosphorus can be achieved over the 60 days observation in maintaining its high Li storage properties. [3]

References:

[1] Xianhong Rui, Xiaoxu Zhao, Ziyang, Lu, Huiteng Tan, Daohao Sim, Huey Hoon Hng, Rachid Yazami, Tuti Mariana Lim, Qingyu Yan*, “Olivine-Type Nanosheets for Lithium Ion Battery Cathodes”, ACS NANO 7 (6), (2013), p5637-5646

[2] Dan Yang, Ziyang Lu, Xianhong Rui, Xiao Huang, Hai Li, Jixin Zhu, Wenyu Zhang, Yeng Ming Lam, Huey Hoon Hng, Hua Zhang,* Qingyu Yan*, “Synthesis of two-dimensional transition metal phosphates with highly ordered mesoporous structures for lithium-ion battery application”, Angewandte Chemie 53 (35), (2014), p9352-9355

[3] Yu Zhang, Huanwen Wang, Zhongzhen Luo, Hui Teng Tan, Bing Li, Shengnan Sun, Zhong Li, Yun Zong, Zhichuan J. Xu, Yanhui Yang, Khiam Aik Khor, Qingyu Yan*, “An air-stable densely packed phosphorene-graphene composite towards advanced lithium storage properties”, Advanced Energy Materials 6 (12), (2016), p1600453.
ALD-Coated Graphite Anode Materials for Improved Cycle Life, Calendar Life, and Safety of Li-Ion Cells
Authors: Dahlberg Kevin , Trevey James E , Dameron Arrelaine , Meyer Harry M , Ruther Rose Emily , Wood David L , Stevenson Lisa , Townsend Dennis
Published: February 2020

Lithium-ion battery-based energy storage is widely regarded as the best technology to realize affordable electrification of automobiles (hybrids and EVs), buses, and ships. However strategies to realize higher energy density and lower cost come at the expense of cell lifetime and safety. Extensive effort has been devoted to studying the effects of ALD coatings on cathode materials, with varying reports of the impact on cycle life of full cells. However, ALD coatings on graphite anode materials have received relatively little attention, despite the role of the negative electrode in predominant energy loss mechanisms in graphite-based full cells. In this work we studied the effects of ALD coatings of Al2O3 and other chemistries on graphite active material powders, in full 95mm x 64mm pouch cells considering cycle life, calendar life, and thermal stability via ARC. We further studied the effects of different voltage windows including “high voltage” 4.4V charge limit. We found that the chemistry of the negative electrode was fundamentally altered, including SEI chemistry, growth, and resistance; and capacity slippage electrode misalignment. FTIR spectroscopy and depth-profiling XPS confirmed changes in graphite surface and SEI chemistry with ALD coatings. The result in full cells was a more stable SEI that gave significantly longer cell lifetimes and enhanced safety under conditions of high-temperature cycling, high-temperature storage, and high-voltage cycling. Moreover, we found the effects of ALD coatings on cathodes were enhanced in “Dual ALD” cells combining ALD-coated cathode materials and ALD-coated anode materials.
Microstructural Limits and Extensions of Porous Electrode Theory
Authors: Campos Juan Alfonso , Battiato Ilenia , García R. Edwin
Published: February 2020

Newman-type models, are the most widely used implementation of porous electrode theory to simulate Li-Ion batteries by both industry and academia [1]. These models show great robustness, fidelity, and for most applications they require to fit ~80 material parameters to match the measured experimental data. While it is always possible to match the experimental results with these models, a methodology to quantify their veracity and identify the regions of validity remains unavailable. In general, it is necessary to identify the conditions under which the micro and macroscopic scales are decoupled, and conditions where the assumptions associated to using average microstructural properties remain enforced. In this paper, the effect of the microstructure in the modeling and validity of Newman-type models is described by extending the analytical method proposed by Battiato and coworkers [2], based on the formal application of upscaling techniques, with the use of microstructurally averaged properties, e.g., [3]. Comparisons against microstructurally resolved models are made.

[1] J. Newman and W. Tiedemann. “Porous-electrode theory with battery applications." AIChE J., 21, 25-41, 1975.

[2] Harikesh Arunachalam, Simona Onori, and Ilenia Battiato. “On Veracity of Macroscopic Lithium-Ion Battery Models" J. Electrochem Soc, 162 (10), A1940-A1951, 2015.

[3] R. García-García, and R.E. García. “Microstructural Effects on the Average Properties in Porous Battery Electrodes" Journal of Power Sources 309, 11-16, 2016.
Toward Soluble, Stable Organic Electroactive Materials for Non-Aqueous Redox Flow Batteries
Authors: Odom Susan A , Kaur Aman Preet , Attanayake Harsha A , Casselman Matthew D , Milshtein Jarrod David , Kowalski Jeffrey A , Elliott Corrine F , Parkin S R , Risko Chad , Anthony John , Brushett Fikile R.
Published: February 2020

Commercial redox flow batteries (RFBs) contain highly acidic and corrosive electrolytes, a cause for concern with widespread use to due concerns about safety and environmental contamination. Replacing these electrolytes with non-aqueous equivalents allows for a safer storage medium. Additionally, utilization of organic electroactive materials may lead to more scalable technologies that do not rely on mined materials such as vanadium and lithium. Furthermore, non-aqueous electrolytes could enable a 2- to 3-fold increase in operating voltage due to the wider operating voltage of non-aqueous systems. Despite the promise for a safer, scalable, higher energy system, the number of organic compounds reported in non-aqueous flow battery systems has been limited to a few classes of compounds, many of which suffer from instability and/or insolubility, especially in charged states. Our recent efforts have focused on the development of organic electron donors and acceptors with stable oxidized and reduced states. This presentation will focus on design strategies utilized to increase molecular stability and solubility in all relevant states of oxidation while keeping syntheses short, high yielding, and scalable. In particular, we highlight the design, synthesis, and electrochemical analysis of new phenothiazine and napthoquinone derivatives designed to serve as one- or two-electron donors. We show that tactical placement of substituents leads to improved stability and increased solubility. Additionally, a new approach to modification of redox potentials using strategic substituent placement will be presented.
Ambient Temperature Aqueous Sulfur Batteries for Ultralow Cost Grid Storage
Authors: Li Zheng , Pan Menghsuan , Su Liang , Tsai Ping-chun , Valle Joseph M. , Badel Andres F , Eiler Stephanie L. , Brushett Fikile R. , Chiang Yet-Ming
Published: February 2020

Sulfur is an attractive reactant for such concepts due to its exceptionally low cost, high natural abundance, and high specific and volumetric capacity owing to its two-electron reaction. Taking the cost-per-capacity (e.g., in US$/Ah) as a metric, sulfur has the lowest cost of any known electrode-active compound with the exception of water and air. However, in order to take advantage of sulfur’s low-cost potential, all other components must also have low cost.

Towards enabling ultralow cost grid storage, we demonstrate an ambient-temperature aqueous rechargeable flow battery that uses low-cost polysulfide chemistry in conjunction with lithium or sodium as the working ion, and an air-breathing cathode. Four different laboratory cell constructions are used to test the half-cell and full-cell reactions, including a pumped air-breathing cell that exhibits stable room-temperature cycling over 960h with a lithium polysulfide anolyte and dissolved lithium sulfate catholyte. In this approach the solution energy density is 30-150 Wh/L, which exceeds current solution-based flow batteries, and the chemical cost of stored energy is exceptionally low, especially when using sodium polysulfide (~1 US$/kWh). Results of techno-economic modeling are also presented, which show that when projected to full system-level, this new approach has energy and power costs that are comparable to those of pumped hydroelectric storage (PHS) and underground compressed air energy storage (CAES), but without their geographical and environmental constraints.

This work was supported as part of the Joint Center for Energy Storage Research, an Energy Innovation Hub funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences.
Hydrogen-Vanadium Reversible Fuel Cell Crossover Study
Authors: Dowd Regis Paul , Powers Devon , Wycisk Ryszard , Pintauro Peter N. , Nguyen Trung Van
Published: February 2020

For vanadium-based redox flow battery systems, vanadium crossover occurs through the ion exchange membrane, which results in self discharge and variations in electrolyte concentration. VO2
+ crossover rate through various Nafion membranes was measured directly with a hydrogen-vanadium reversible fuel cell. Measuring crossover of electrolyte species directly with a fuel cell vice an idealized dual-chamber system, allows for determining diffusivity under actual fuel cell testing conditions. The crossover rate in an actual fuel cell is expected to be different due to the migrational effect across the membrane, the reduction in the membrane area due to the solid phase of the electrodes, the compressive forces exerted on the membrane during fuel cell assembly, the effect of the membrane electrode assembly hot pressing technique on membrane thickness and surface chemistry, and the fuel cell operating conditions (i.e. electrolyte flow and pressure on each side of the membrane). This new in-situ technique for measuring crossover with an actual fuel cell is shown to be reliable and easy to use. Electrospun Nafion/PVDF single-fiber blend membranes were also fabricated and tested in the hydrogen-vanadium reversible fuel cell. The electrospun membranes led to lower crossover rates and high fuel cell performance.
(Invited) Highly Proton Conducting Membranes for Electrochemical Energy Conversion Applications
Authors: Herring Andrew M , Motz Andrew R , Kuo Mei-Chen , Nguyen Vinh
Published: February 2020

There is still a need for membranes that operate in proton exchange membrane (PEM) fuel cells at hotter and drier conditions than can be achieved with current materials, >100°C and <50%RH. One approach pursued by us is the use of inorganic super acids as the heteropoly acids (HPAs) r zirconium phosphonates. HPAs are a sub group of the large class of metal oxygen clusters known as polyoxometalates in which a central heteroatom is surrounded by a number of W or Mo oxygen octahedra. For proton conductivity it is desirable that a strong negative charge be delocalized across the whole anion so that the proton will be as dissociated as possible. This limits the choice of HPA to the spherical tungsten based Keggin anion with as light as possible a heteroatom. This limit is reached with Si as the P based HPA is known to decompose in the presence of peroxide and the electron deficient nature of B renders the spherical Keggin anion unstable. Many fundamental studies have been undertaken on solid state HPA systems. These studies indicated that despite the original report in the early 80’s that HPA had the highest proton conductivity reported at that time, that when dry there proton conductivity was disappointingly low at moderate temperatures.

We have doped both PFSA and PBI polymers with HPA and shown that both approaches lead to membrnes with much improved properties for proton cnduction under higher an drier conditions. The HPA/PBI/phosphorics acid system that we have developed may be used to investigate direct fuel cells with a number of fuels beyond hydrogen as the membranes can opearte at temperatues >160°C. Our most ambitious approach is to make monomers from HPA and immobilize the HPA by polymerization into hybrid systems. In order to functionalize the Keggin anion one W oxygen octahedra is removed and a Si or P based organic functionality introduced that may be a monomer or a tether to a functionalized polymer backbone. Our first generation materials based on divinyl functionalized HPA and acrylate chemistry produced films with impressive conductivities, >100 mS cm-1 T >80°C and 50% RH. This model system contained ester linkages that we think may be hydrolysed under the harsh conditions of fuel cell operation and so we attached HPA via phosphonate linkages to perfluorinated polymers. Very recently we have fully perfected this chemistry and can now produce large area thin high loaded HPA films that have demonstrated high performance fuel cell operation. We will show performance data in both hot and dry fuel cell operation and also durability data that shows the materials pass the DOE tests. These membranes are currently being investigated as seperators in redox flow batteries using a large number of redox couples.
Pore Level Liquid Protrusion Under Mixed Wetting and Geometry
Authors: Herescu Alexandru
Published: February 2020

This study provides insight into liquid percolation through the pores of a porous medium such as the Gas Diffusion Layer of a PEM fuel cell. The variety of pore sizes and geometries corroborated with mixed wetting properties contribute to complex transport features which are only marginally understood and controlled. The percolation pressure required for liquid protrusion through a pore is a strong function of geometry and pinning characteristics, as evidenced by numerical simulations of the process. These results show an alternative view to the capillary tube model and sheds light onto the evolution of the gas-liquid interface as the liquid passes through the pore. Geometrical and pinning features need to be included in an accurate pore model, a better understanding in this direction can aid in the development and characterization of porous materials for energy applications and beyond.
One-Step Synthesis of Nanostructured Co3O4 Film on Nickel Foam As Electrode for Supercapacitor Application
Authors: Wang Yang , Roller Justin , Maric Radenka
Published: February 2020

In recent years, supercapacitors have drawn considerable interest from researchers as an alternative energy storage device to secondary batteries. They offer advantages such as high power density, high columbic efficiency and long cycling life [1, 2]. Among the transition metal oxides investigated for redox reaction based supercapacitors (pseudocapacitors), Co3O4 is of special interest due to its high theoretical specific capacitance (up to 3560 F g-1) and relatively low cost [3, 4]. However, low rate capability and poor cycling performance as a result of relatively low electrical conductivity limits its practical application in supercapacitors. Development of nanostructured Co3O4 materials offers a promising solution to this challenge as the transport pathways of electrons and ions are inherently short.

Nanostructured Co3O4 film deposited on nickel foam has been prepared by an economical and scalable flame combustion method in one step, namely reactive spray deposition technology (RSDT). The microstructure of the electrode is investigated by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The nanostructured electrode provides high specific surface area and improves the kinetics of redox reaction [5]. The porous structure facilities the penetration of electrolyte and shortens the diffusion path of ions [6]. Electrochemical performance of the as-prepared Co3O4/Ni electrodes is evaluated by cyclic voltammetry, galvanostatic charge-discharge cycling and electrochemical impedance spectroscopy in coin-type (CR2032) half-cells.

References:

X. Xia, Y. Zhang, D. Chao, C. Guan, Y. Zhang, L. Li, X. Ge, I.M. Bacho, J. Tu, H.J. Fan, Nanoscale, 6 (2014) 5008.

Z. Yu, L. Tetard, L. Zhai, J. Thomas, Energy Environ. Sci., 8 (2015) 702–730.

C.Z. Yuan, L. Yang, L. Hou, L. Shen, F. Zhang, D. Li, X. Zhang, J. Mater. Chem., 21 (2011) 18183–18185.

X.X. Qing, S.Q. Liu, K.L. Huang, Y.P. Yang, Z.G. Lu, D. Fang, X.X. Liang, Electrochim. Acta, 56 (2011) 4985–4991.

G. Wang, L. Zhang, J. Zhang, Chem. Soc. Rev., 41 (2012) 797–828.

C.Z. Yuan, J.Y. Li, L.R. Hou, X.G. Zhang, L.F. Shen, X.W. Lou, Adv. Funct. Mater., 22 (2012) 4592.
Beyond the Hour and the Day: The Need and Technologies for Long-Duration Electrical Storage
Authors: Manser Joseph S. , Spangher Lucas , Heffner Reid R. , Babinec Susan J. , Albertus Paul S.
Published: February 2020

As California, Hawaii, Vermont, and New York implement renewable portfolio standards of 50% and higher, long-duration electrical storage is one option that could play a key role in balancing intermittent renewable output. Long-duration storage serves the purpose of both supplementing intermittent renewable generation and replacing traditional fossil-fuel-powered peaker plants and, for the purpose of this talk, will be defined as a duration of 8 to 50 hours, or even longer. A recent NREL analysis of California’s future grid estimated that 15-28 GW of storage with an 8-h duration would be needed in order to maintain electricity prices at affordable levels if 50% of the state’s electricity was generated from solar PV. But these long-duration systems will be adopted only if they are safe, durable, and capable of storing energy at capital costs far lower than the 150 $/kWh (installed) that is targeted for approximately 5-hour systems. This presentation will help define a new long duration application area for electrochemical engineers and cover the following aspects of the concept: (i) What storage duration is required in a geographical region given various capacity values of renewable generators and degrees of renewable penetration? (ii) What system attributes are needed for long-duration storage? What are the appropriate approaches to balance capital cost, lifetime, energy density, and round-trip efficiency? (iii) What electrochemical storage technologies are most promising for long duration storage? Can lithium-ion serve these applications, or will new and unique battery and flow battery systems provide performance and cost advantages? (iv) How can various system design paradigms minimize balance of plant costs and the levelized cost of storage? (v) What is the broader set of technologies (other than batteries) that can address long duration storage for high renewables penetration (e.g., hydrogen storage, other electrical storage technologies, carbon capture and storage) of which electrochemical researchers should be aware?