bluuebunny/crossref_metadata_2025_split huggingface dataset:
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)
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.
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.
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.