bluuebunny/crossref_metadata_2025 huggingface dataset:
Developing of Novel Electrorefining Process of Titanium from Cuti Alloy in K-Free Molten Salt
Authors: Ri Vladislav Ernstovich , Lee Young-Jun , Yoo Bung-Uk , Nersisyan Hayk , Lee Jong-Hyeon
Published: February 2020

There are many researchers studied electrochemical behavior of Ti ions introduced by addition of K2TiF6, TiClx and TiFx in chloride and fluoride electrolytes, however, there is no research about BaTiF6. Thus, this research contains a novel process of usage of BaTiF6 as a solvent in fluoride molten salt at 750 ºC. There is also a novel process of Ti ingot preparation is described, where electrorefining of Ti from CuTi alloy is one of technological step (Fig. 1). Electrochemical behavior of Ti ions was investigated by cyclic voltammetry and anodic polarization measurement methods. Then Ti electrorefining process was investigated by chronopotentiometry method using CuTi rod as an anode (counter electrode). Electrolysis of Ti was performed at various conditions (current density, temperature) to study morphology of deposited Ti. SEM and EDS analyzes were used to investigate deposition properties and composition. ICP and FTIR analysis were applied to detect titanium concentration and determine titanium valence state in quenched salt samples at various conditions. The crystal size of Ti was up to 200 µm in most cases, what allowed successful separation of the deposit from salt, and then obtaining of Ti ingot by arc melting process.
Effect of Brightener Concentration on Recrystallization Process of Electroplated Cu
Authors: Yang Cheng-Hsien , Lee Yu-Wei , Lee Cheng-Yu , Huang Yu-Hsuan , Ho Cheng-En
Published: February 2020

It is well-known that self-annealing of as-electroplated Cu would cause remarkable microstructure transition in few hours, inducing grain growth accompanied by elimination of grain boundaries and crystallographic defects that determine the physical/chemical characteristics (e.g., resistivity, and hardness) of the Cu film. Organic additives (e.g., brightener, suppressor, and leveler) and current density are two important factors of Cu self-annealing. The brightener is an indispensable organic additive for the superfilling of Cu electroplating in blind-/through-hole structure. Hence, the focus of this study is to probe into the effect of brightener concentration (C
b) on the self-annealing behavior of electroplated Cu. The crystallographic evolution of electroplated Cu, including grain size distribution, crystallographic orientation, grain boundaries, and residual strain, were investigated by means of in-situ X-ray diffraction (XRD) and electron backscatter diffraction (EBSD). Additionally, the impurity distribution on the Cu film (e.g., C, O, S, and Cl) was investigated by a time of flight secondary ion mass spectrometer (TOF-SIMS). The research results indicated that the brightener concentration is a very important factor of Cu microstructure evolution and impurity distribution. The information advances our own knowledge of electrochemical metal recrystallization.

Figure 1
Fabrication of Localized Silicon-on-Insulator Based Rhombus-Shaped Channels in Silicon
Authors: Ogini Martins , Voyantzis Mitchell , Koech Philemon Kipsang , Alice Francis Aneeta , Mohan Susmitha , Deo Makarand , Albin Sacharia
Published: February 2020

Fabricating localized silicon-on-insulator (LSOI) on bulk silicon eliminates the need for using expensive SOI wafers for silicon waveguides and MEMS applications. One of the most important building blocks in silicon photonics is optical waveguide, which usually consists of silicon surrounded by silicon dioxide with refractive indices of 3.5 and 1.5, respectively. It was observed that the SOI wafer puts restrictions on the integration of electronics and photonics because the buried oxide is too thin for field confinement. Hence, fabrication of LSOI in standard silicon wafers is considered to have precise control of the oxide thickness which will lead to effective integration of electronic and photonic devices. We used rhombus-shaped channel method in the fabrication of LSOI structure that can be produced on any part of a bulk silicon wafer. The rhombus-shaped SOI is governed by three main parameters namely the width of silicon opening between two rhombic shapes (W), mask width (M), and depth of the trench (D) as shown in Figure 1a. This method uses CMOS-compatible processes such as photolithography, thermal oxidation, reactive-ion etching and orientation dependent wet etching. Unlike conventional methods, this method relies on fewer process steps by eliminating the need for deposition, too many oxidation, etching steps, and hydrogen annealing process to smoothen the surface. In this work, the starting material is a silicon wafer with a 500nm silicon nitride layer which serves as a mask during etching. The Si wafer is cleaned using RCA method. A mask with squares dimensions ranging from 100µm to 200µm is used to create patterns on the silicon nitride layer. Reactive ion etching is used to etch the exposed nitride layer and etched 3µm of silicon (D) to expose the <110> plane in the silicon wafer. Then orientation dependent etching is performed using Tetramethylammonium hydroxide (TMAH) with isopropyl alcohol (IPA) as an etchant to obtain the rhombus-shaped structure. It resulted in a Si structure with funnel width of 14µm ascertained from SEM image as shown in Figure 1b. Figure 2 shows an alternative fabrication process without the silicon nitride; it was simulated using Intellietch software giving an island of silicon after the final step of thermal oxidation. Further studies on the effects of etching, thermal oxidation time, and oxide thickness on the SOI funnel width FW and depth Pd will be presented.

Figure 1
Epitaxial Grown Ferroelectric Polymers on Graphene Layer for Non-Volatile Transistor Memory with Graphene Channel
Authors: Kim Kang Lib , Park Cheolmin
Published: February 2020

Controlling the crystal orientation is important to ferroelectric polymers to enhance ferroelectric properties. Here, we demonstrated non-volatile ferroelectric polymer memory with exfoliated monolayer graphene and epitaxial grown ferroelectric polymer. The mechanically exfoliated and transferred graphene was used as channel and epitaxial substrate for poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE). The epitaxial interaction between graphene and ferroelectric polymer results aligned chain-axis of polymer along the graphene’s 3-fold symmetry and provide improved remnant polarization and coercive field. Furthermore, the epitaxial grown ferroelectric polymer and monolayer graphene with Cr/Au source and drain electrode and few layer graphene for gate electrode demonstrated non-volatile graphene transistor memory with retention and endurance cycles more than 10,000 sec and 1,000 times, respectively.
Structural and Electronic Assessment of Heterogeneous PANI@UiO-66 Composite Photoelectrode Material
Authors: Shanahan Jordan James , Kissel Daniel S. , Sullivan Eirin
Published: February 2020

Global environmental and economic impact from carbon emission has sparked abundant interest in the development of renewable photocatalytic based energy sources. In the continued search for new and versatile photocatalytic materials, metal organic frameworks (MOFs) have emerged as highly promising prospects, consisting of metal ions or metal ion clusters bridged by organic linkers to form a porous 3-dimensional array. Attributes of MOFs include ease of tunability coupled with well defined surface areas and structural alignment. UiO-66, a Zr-bdc MOF, was chosen as the photocatalytic center for this study due to its unprecedented chemical and thermal stability while still lacking effective valence-conduction band alignment for visible light absorption or efficient charge transport. To address the latter, a conductive organic polymer [polyaniline (PANI)] was grown in-situ to produce a novel heterogeneous composite film. Pre-functionalized UiO-66-NH2 was also conceived for more direct interaction within the framework. Major effects in both electronic and structural properties were observed for both unfunctionalized and amine functionalized PANI@MOF composites. Structural attributes were determined using infrared spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy. Electronic properties were determined using four-point probe measurements, and diffuse reflectance UV-Vis Spectroscopy.
(Invited) Diamond Electrodes for Electro-Chemical Synthesis
Authors: Mollart Tim , Zarrin Hossein
Published: February 2020

Boron doped diamond (BDD) electrodes have remarkable electrochemical properties, they are enabling novel electrochemical processes, from advanced oxidation liquid waste treatment to new types of electrochemical sensors and emerging new environmental processes. As an allotrope of carbon the properties of diamond electrodes have been shown to be a function of their crystallinity, boron doping concentration and non diamond (graphitic) carbon content. Optimized solid free-standing (not a coating) electrodes with high crystallinity and heavily boron doped can have solvent windows > 4 V (versus SCE) combined with metal like conductivity.

Many industrial chemical processes can benefit from the ability of diamond electrodes to deliver high oxidation and reduction potentials while suppressing the electrolysis of water. In the anodic region due to their high physical, chemical and electrochemical stability the hydroxyl and sulfate radical can be formed enabling direct or indirect electrochemical oxidation of dissolved species in the electrolyte. At the anode species such as nitrates can be reduced to nitrogen and since water electrolysis is suppressed in some conditions these processes can be carried out at near 100% Faraday current efficiencies

Diamond electrodes are being used in electrochemical advanced oxidation processes (AOPs) for removal of recalcitrant organic pollutants in the industrial liquid wastes by mineralizing them to CO2 and H2. Hydroxyl radicals have a high oxidation potential (2.80V) when compared to ozone (2.08V) and hydrogen peroxide (1.27V) and since the formation takes place directly at the anode by electrochemical oxidation, these systems have been found to be highly effective and universally applicable.

In environmental processing and recycling electro oxidation is emerging as a way of making closed cycle chemical processes for e.g. materials recovery from wastes and regeneration of process effluents. Diamond electrodes can be used to simultaneously remove dissolved organics contaminants and restore the oxidation potential of a process effluent. Enables a reduction of the need for chemical dosing and the disposal of chemical wastes. In this talk we will explore some examples of these new electrochemical processes and discuss the potential for new processes that exploit the cathodic properties of diamond electrodes.
Quantitative Analysis Effect of the Cathode Catalyst Layer in PEMFC with Various Ionomer By Protonic Resistance
Authors: Xue Qiong , Yang Dai-jun , Li Bing , Zhang Cunman
Published: February 2020

Low efficiency of Polymer Electrolyte Membrane Fuel Cells (PEMFC) is one of the barriers for Fuel Cell Vehicles (FCV) to commercialize. Cathode catalyst layer (CCL) is responsible for main efficiency losses in PEMFC because of both insufficient oxygen reduction kinetics and proton conduction losses within the CCL. Therefore, quantitative analysis of the proton impedance of CCL and optimization of the structure of CCL are great significant to promoting the practical application. The optimized ionomer content of the CCL can effectively reduce the ionic resistance and boost mass transfer. In this work, preparing a series of membrane electrode assemblies by adjusting the ionomer content of the cathode catalytic layer, the protonic impedance of the corresponding CCL is estimated by electrochemical impedance spectroscopy (EIS) in absence of oxygen using a physical impedance model. The performance of the prepared CCLs are comprehensively evaluated by electrochemical techniques such as polarization curves, cyclic voltammetry (CV), and EIS in different gas supply conditions (H2/air, H2/N2). This method has demonstrated the quantitative effect on the performance and evaluated microstructure of CCL with different ionomer content. The hydrogen/nitrogen EIS method is used to quantitatively analyze the proton impedance of CCL with different ionomer content, and the effect on the performance of the membrane electrode assemblies, which could be contributed to construct composition and structure of CCL and improve the catalyst utilization rate of the CCL. It is of great significance to improve the performance and reduce costs of PEMFC.
Investigation of Cell Microenvironment Effect on Cell Behaviors Using Electrochemical Scanning Probe Microscopy
Authors: Li Fei
Published: February 2020

Cell microenvironment (chemical, mechanical, electric) directly effects cell functions and behaviors (biology, mechanics, electrophysiology). Study of cell microenvironment effect on cell functions and behaviors is important for understanding the pathological mechanism of diseases (heart disease, cancer). Different kinds of hydrogels, which is an ideal material to mimic 3D extracellular matrix (ECM) of cell, have been developed and used to construct 3D cell microenvironment in vitro. To understand the effect of cell microenvironment constructed by hydrogels on cell behaviors, the technique which can characterize both the property of hydrogels and the topography and multi-behaviors of cells at mm/nm scale in an in-situ, non-damage way is needed. Scanning electrochemical microscopy (SECM) and scanning ion conductance microscopy (SICM) are two kinds of electrochemical scanning probe microscopy with the capability of providing morphology and performing chemical analyses of cells in an in situ, reversible and non-destructive way.

In our work, we firstly constructed cell microenvironment based on three kinds of functional hydrogels (i.e., self-healing hydrogels, magnetic hydrogels and hydrogel microwell arrays). Then SECM was applied to in-situ track the self-healing process of hydrogel, the H2O2 consumption across magnetic hydrogel nanocomposites and the oxygen permeability across hydrogel microwell arrays. The effect of mechanical microenvironment on the redox state of cardiomyocytes and cardiac fibroblasts was also characterized by SECM. To further characterize the cell morphology at nm-scale, we also home built our SICM system and used it to characterize the cell morphology and cell volume on hydrogels with different stuffiness.

Figure 1
Ex Situ and Operando Characterization of Energy Storage Materials By Benchtop XAFS and XES
Authors: Jahrman Evan , Ditter Alex , Holden William , Pellerin Lisa , Seidler Gerald T. , Bradshaw Liam , Polzin Bryant J. , Fister Timothy T
Published: February 2020

Advanced x-ray spectroscopies permit the interrogation of a material’s local electronic structure in an element-specific manner. In particular, these techniques reveal the speciation and ligand environment of an electroactive element and can provide direct insight into the state-of-charge and state-of-health of a battery. Despite their utility, the scientific impact of advanced x-ray spectroscopies is necessarily constrained by the availability of instrumentation. For x-ray absorption fine structure (XAFS) and x-ray emission spectroscopy (XES), studies are traditionally performed at synchrotron x-ray facilities. These facilities frequently serve to push the forefront of science and, as a result, necessarily operate under an access model which excludes projects which require routine analytical characterization, rapid feedback, or regular access.

Over the last four years, our group at the University of Washington has developed several families of laboratory-based instruments to expand the accessibility of advanced x-ray spectroscopies. For the study of transition metal chemistry, we have constructed two Rowland circle spectrometers based upon related designs. Both spectrometers provide energy resolutions comparable to that observed at a synchrotron endstation. Their designs are also highly efficient, allowing studies to be completed with commercial x-ray tube sources in time scales relevant for materials research programs. For many such studies, the instrumentation can generate satisfactory spectra in a matter of minutes, permitting operando studies of battery materials at charge rates in excess of 1C.

From the standpoint of instrumentation, a brief review of the present designs is presented with emphasis on recent advances in extended-XAFS capabilities. Differences between the spectrometer designs and the advantages of each will also be highlighted. Regarding materials inquiry, a survey of the above instrument’s application to energy storage research is provided. This will include XAFS analyses of two systems of nanoparticle compounds which were engineered to be catalysts or pseudocapacitors. These results will facilitate a review of the information attainable from the underlying technique. The rich electronic structure of vanadyl phosphate cathode materials, as well a suite of vanadium oxides, is probed via valence-to-core XES (VTC-XES). Finally, operando x-ray absorption near-edge structure (XANES) results obtained from a pouch cell containing a nickel-rich NMC cathode at a variety of charge rates are presented.
Operando SANS and Synchrotron Radiography Characterization of the Carbon Cathode from Lithium Sulfur Batteries
Authors: Jafta Charl J , Risse Sebastian , Prévost Sylvain , Trapp Marcus , Dai Sheng , Ballauff Matthias
Published: February 2020

In recent years lithium sulfur (Li-S) battery research became an important route to go beyond traditional lithium ion batteries. Among various battery systems, Li-S batteries have comparatively high theoretical energy density and lower cost, making Li-S batteries very promising for next generation secondary batteries. However, the current energy density achieved, and significant capacity decay with cycling, do not fulfill the needs for industrialization. To overcome the drawbacks of Li-S batteries and improve their performance, better understanding of the reaction mechanism and how this relates to capacity decay is necessary. A great deal of ex-situ characterization research has been conducted that has shed light on the working mechanism. Considering the complexity of the solution and interfacial chemistry, with multiple intermediate lithium polysulfides and the inherent multi-electron reaction pathways, we developed advanced operando techniques to provide new information on the dynamic processes occurring at the electrode interface.

In this presentation operando small angle neutron scattering (SANS) results will be shown, specifically shedding light on the precipitation process of S8 and Li2S as a function of state of charge. We address the question of whether precipitation of S8 and Li2S in the charged and discharged states, respectively, occurs in the pore or on the surface of the carbon cathode. This is a question that enjoyed very little discussion, due to the challenges in directly measuring the precipitation. Operando radiographic evidence will also be shown regarding the distribution of precipitates in the electrode. These results will increase the understanding of the charge / discharge mechanism of Li-S batteries and will contribute to the advancement of this battery chemistry.
Multi-Physics Computational Model for Lithium-Ion Batteries Under Mechanical Abusive Loading
Authors: Xu Jun , Liu Binghe
Published: February 2020

Lithium-ion batteries (LIBs) have been regarded as one of the most promising alternative energy sources in the automotive industry. Extreme conditions, such as mechanical abuse, thermal abuse, and charging/discharging abuse can lead to irreversible and catastrophic consequences (e.g., fires or explosions). Thus, LIB safety has received extensive attention, particularly for hazardous consequences caused by mechanical abusive loading during inevitable vehicle accidents. Given their complicated multi-physics nature, modeling LIB behavior subject to mechanical abusive loading is considered difficult. Therefore, models for mechanical abuse conditions have been gradually developed in the past several years. Typical behavior of LIB cells subject to compression mainly include mechanical deformation, triggering of an internal short circuit, and leading of the thermal runaway in time sequence. Five sub models (i.e., 1D battery, short circuit, thermal, thermal runaway, and mechanical models) are included in the integrated model. Mechanical and thermal models can be coupled through the deformation and temperature. Mechanical and short circuit models are one-way coupled through the stress state. The short circuit, thermal runaway, and 1D battery models are coupled with the thermal model through temperature and heat. 1D battery and short circuit models models are coupled with voltage and current Compression experiments were designed and conducted to calibrate the model, and the load–time, voltage–time, temperature–time, and deformation morphology are suitably matched in the computation and experiments. Finally, three governing factors in mechanical abuse loading (SOC value, compression speed, and compression displacement) are discussed utilizing this model to reveal the underpinned mechanisms. These studies reveal the underlying mechanism for the mechanical abuse safety of LIBs. This model can lay a solid foundation to understand LIB electrochemical and mechanical integrity, as well as provide critical guidance for battery safety designs.

Keywords: Lithium-ion battery; Multi-physics model; Mechanical abuse; Short circuit; Thermal runaway
Thermally Stable Aramid Nanofiber Separators for Energy Storage
Authors: Patel Anish , Wilcox Kathryn , George Ian , Juneja Rishabh , Lutkenhaus Jodie L.
Published: February 2020

A battery separator prevents internal short circuiting while also allowing ion transport between the two electrodes. Catastrophic battery failure, which can lead to economic costs in damages and serious injuries, can result from a failed separator due to shrinkage or puncture. Two major causes of this can be lithium dendrite formation and mechanical deformation. This is a major issue preventing the advancement of safe energy storage technologies. Mechanically and thermally robust separators offer an alternative approach for preventing battery failure under extreme conditions such as high loads and temperatures. Unfortunately, a robust separator must also maintain adequate ion transport properties and, in order to be a feasible replacement for commercial energy storage separators, be easily processed. Recently, aramid nanofibers (ANFs), a novel nanoscale building block derived from Kevlar® fibers, have been successfully used as a mechanical reinforcement filler for composite materials and show promise as battery separators. Here, we fabricate pure ANF separators through the dissolution of bulk Kevlar® fibers and vacuum-assisted self-assembly. We investigate the thermal behavior and degradation of ANF separators at high temperatures as well as mechanical properties of the separator at elevated temperatures. We also characterize ion transport properties and electrochemical performance of a Li-ion battery utilizing the ANF separator. Finally, we compare the pure ANF separator to common commercially available separators. ANF separators may allow for safer batteries under extreme conditions while being easily processable. In particular, ANF separators show excellent thermal stability by exhibiting no thermal events or mechanical deformation up to 400 oC.
Triangular Carbon Quantum Dots with Narrow Bandwith Emission for Leds
Authors: Fan Louzhen
Published: February 2020

Carbon quantum dots (CQDs) have emerged as promising materials for optoelectronic applications on account of carbon’s intrinsic merits of high stability, low cost and environment-friendliness. However, the CQDs usually give broad emission with full width at half maximum exceeding 80 nm, which fundamentally limit its display applications. We demonstrate multicolored narrow bandwidth emission (full width at half maximum of 29 to 30 nm) from triangular CQDs with a quantum yield up to 54 to 72%. Detailed structural and optical characterizations together with theoretical calculations revealed that the molecular purity and crystalline perfection of the triangular CQDs are key to the high color-purity. Moreover, multicolored light-emitting diodes based on these CQDs displayed good stability, high color-purity and high-performance with maximum luminance of 1882 to 4762 cd m-2 and current efficiency of 1.22 to 5.11 cd A-1. This work will set the stage for developing next-generation high-performance CQDs-based light-emitting diodes.
Recent Mechanistic Understanding of Oxygen Reduction Reaction over Pt-Supported 3D Carbon Nanofiber Catalysts
Authors: Liu Bin , Xu Jiayi , Elangovan Ayyappan , Li Jun
Published: February 2020

For both proton exchange membrane and direct methanol fuel cells, oxygen reduction reaction (ORR) is a performance-determining step. While Pt has been established as a standard bearer in ORR catalyst development, practical long-term applications require continuing effort to pursue active, stable, as well as affordable materials as alternatives to precious metals.

In this talk, carbon-based vertically aligned carbon nanofibers (VACNFs), essentially a stack of conical graphitic structures, will be discussed as highly promising ORR catalysts. In an alkaline medium, at -0.4 V applied potential, the current density measured on VACNF cathode is twice more than that measured with commercial Pt catalyst (Pt/C). Molecular insights have been gained through the use of Density functional theory (DFT) calculations to: (1) reveal interactions of ORR intermediate species at the catalytically active sites; and (2) elucidate the origin of catalytic activities of VACNF under reaction conditions. Specifically, semi-periodic fishbone-like stacked graphene sheets, bare or terminated with H and OH, have been employed to understand the impact on ORR mechanism and corresponding reactivities. Bindings of O2, O, and OH at various configurations obtained from DFT are then used as descriptors to assess catalyst performance against simple Pt (111) and Pt (211) surfaces.

In addition, Pt nanocatalysts supported on VACNF (Pt/VACNF), which can push the ORR current density even higher, will be discussed as well. Again, with DFT, a model with Pt anchored at the VACNF edges was proposed to investigate the functionalities of Pt/VACNF for alkaline ORR reactions. In this talk, both associative and dissociative ORR pathways will be analyzed based on the established models. In particular, the overall computed ORR thermodynamics are shown to be favored toward Pt/VACNF than Pt (111), consistent with experimental results. Nevertheless, the unique interactions of ORR intermediates such as O*, OOH*, and OH* with catalytic active VACNF edge sites, revealed by DFT calculations, suggest intriguing but also complex electrochemistries.
(Invited) Encapsulating Various Sulfur Allotropes Within Graphene Nanocages for Long-Lasting Lithium Storage
Authors: Lu Jun
Published: February 2020

The encapsulation of sulfur within carbon matrices is widely utilized in the cathode of a rechargeable lithium-sulfur battery, whose energy density largely depends on the design of the carbon structure. Here we report an advanced graphene nanocage structure with the capability of hosting both cyclo-S8 and smaller sulfur molecules (S2-4). The cage inner cavity is partially filled with S8 to form a yolk-shell structure that enables free volumetric variation of S8 during (de)lithiation. In the graphene shell of the cage, S8 are downsized to S2-4 to activate extra sulfur loading sites within graphene layers. Importantly, the graphene shell exhibits inward volumetric variation upon (de)lithiation of the loaded S2-4, and the overall electrode strain is thus minimized. This prototyped design promises an ultimate solution to maximize sulfur loading in carbon matrices as well as to circumvent the polysulfide dissolution problem and boost the commercialization of lithium-sulfur batteries in the future.
Influence of Ionic Liquid Electrolyte on Carbon Nanofibres Derived from Oxygen-Functionalized-Graphene for Novel Supercapacitors Electrode
Authors: Oyedotun Kabir Oyeniran , Masikhwa Tshifhiwa Moureen , Lindberg Simon , Matic Aleksandar , Johansson Patrik , Manyala Ncholu
Published: February 2020

A facial force-driven reflux technique was used to develop fibre-like carbon material from freeze-dried reduced graphene oxide (RGO) firstly prepared by using a modified Hummers method. Extensive characterization of the as-synthesized nanofibres material was achieved by various analytical techniques. The carbon nanofibres displayed a high specific surface area with good pore size distributions, which could be beneficial for energy storage applications. Electrochemical measurements of the carbon nanofibre electrodes in a symmetric configuration with aqueous (1 M Na2SO4, 6 M KOH), and protic ionic liquid (1-ethylimidazolium bis (trifluoromethanesulfonly) imide) electrolytes (ILE) displayed excellent electrochemical performance with the dominant electric double layer capacitor (EDLC) behaviour. The fabricated device shows higher electrochemical performance in the ILE due to its larger cell operating potential (3.0 V) as compared with the aqueous electrolytes (0.8 V). The optimized electrochemical properties especially in terms of higher specific energy and superior stability, suggest the material’s potential applications as electrode for supercapacitors.
(Invited) Step-Wise Molecular Self-Assembly on Single-Wall Carbon Nanotube Networks: Towards Development of Delivery Systems of Highly Potent but Difficult to Administer Drugs
Authors: Islam Mohammad F.
Published: February 2020

Single-walled carbon nanotubes (SWCNTs) are increasingly being investigated for biomedical imaging, sensing, and drug delivery. Individual dispersion and coating with biocompatible molecules of SWCNTs are essential to avoid triggering cytotoxicity and to realize these applications. Perhaps the most common method for generating SWCNT-based drug delivery systems involves individually dispersing SWCNTs in water with various biocompatible molecules such as DNA, biopolymers and proteins followed by linking drugs and targeting moieties to the biocompatible coating. Another relatively less frequently exploited approach entails first attaching drugs to SWCNTs and then dispersing with biocompatible molecules, which may also be targetable. Unfortunately, both approaches suffer from low SWCNT dispersion yield and inadequate control of drug loading process, particularly if the drugs are highly potent and difficult to administer. We have developed an extremely facile scheme to generate SWCNT-based drug delivery systems by controllably depositing biocompatible molecules and drugs on preformed SWCNT hydrogels. We first individually dispersed SWCNTs in water using suitable surfactant molecules, concentrated the dispersion to form freestanding hydrogels, and then removed the surfactant from the hydrogel. These surfactant-free SWCNT hydrogels comprise of three-dimensional, isotropic network of individual nanotubes held together via van der Waals interactions the junctions between nanotubes, and have >99% porosity, which allows unimpeded transport of biocompatible molecules and drugs. Furthermore, since many potent drugs are only soluble in non-aqueous solvents, water in the hydrogel can be easily exchanged with other suitable solvents to facilitate drug loading. As a proof-of-concept, we coated SWCNTs within the hydrogels first with drugs such as Doxorubicin, Bleomycin, and Digoxin, then with proteins such as albumins, and lastly dispersed in water through gentle 5 minutes sonication with little or no loss of SWCNT yield. Optical characterizations and imaging show that the albumin/drug/SWCNTs complexes are individually dispersed that the cells readily uptake. To demonstrate robustness of this approach, we coated SWCNTs with polymers prior to decorating with biomolecules/drug layers; the polymer coating was chosen to assist in rapid drug release after cell uptake. Overall, this approach allows precisely controlled, step-wise molecular self-assembly on SWCNTs of any drug and biomolecule combinations, suggesting high potential for development of multifunctional drug delivery platforms utilizing SWCNTs.
(Invited) Sequence-Dependent Stability and Fate of DNA-Wrapped Single-Walled Carbon Nanotubes in Mammalian Cells
Authors: Gravely Mitchell , Safaee Mohammad Moein , Roxbury Daniel
Published: February 2020

The intrinsic fluorescence of single-walled carbon nanotubes (SWCNTs), which exhibits exceptional photostability, near-infrared (NIR) tissue-penetrating emission, and microenvironmental sensitivity, makes them ideal candidates for a variety of biomedical imaging and sensing applications. Single-stranded DNA was found to disperse SWCNTs in water and enable their uptake into mammalian cells through an energy-dependent endocytosis mechanism. Here, we show that the NIR fluorescence behavior and subsequent stability of DNA-wrapped SWCNTs are dictated by the DNA sequence upon entry to cells. We further show that these effects are highly cell-type dependent. Future work includes the development of a cellular uptake and expulsion model that accounts for the sequence-dependent aggregation of SWCNTs.
(Nanocarbons Division Richard E. Smalley Research Award Address) Multifunctional Hybrid Carbon Interfaces
Authors: Prato Maurizio
Published: February 2020

Carbon nanomaterials, including nanotubes and graphene, are particularly well suited for the design and construction of functional interfaces. This is mainly due to the extraordinary properties of these novel materials, which combine mechanical strength, thermal and electrical conductivity.

Our group has been involved in the organic functionalization of various types of nanocarbons, including carbon nanotubes, fullerenes and, more recently, graphene. The organic functionalization offers the great advantage of producing soluble and easy-to-handle materials. As a consequence, since biocompatibility is expected to improve upon functionalization, many modified carbon nanomaterials may be useful in the field of nanomedicine.

During this talk, we will show the latest and most exciting results obtained in our laboratories for applications of carbon nanomaterials in biology, medicine and energy.
Fabrication and Characterization of Microtubular Solid Oxide Cell Supported with Nanostructured Mixed Conducting Perovskite Fuel Electrode
Authors: Gan Yun , Ren Chunlei , Lee Myongjin , Yang Chunyang , Xue Xingjian
Published: February 2020

Mixed ionic and electronic conducting (MIEC) perovskites demonstrate advantages over Ni-cermet as fuel electrode materials for solid oxide cells (SOCs). However, SOCs are primarily electrolyte-supported planar designs in literature when MIEC perovskite fuel electrodes are employed, which are relatively easy to fabricate but usually have high electrolyte ohmic resistance. Perovskite fuel electrode-supported designs are rarely studied particularly for microtubular SOCs. In this research, (La0.3Sr0.7)0.9Ti0.9Ni0.1O3-δ-Sm0.2Ce0.8O1.9 (LSTN-SDC) electrode-supported microtubular cell LSTN-SDC/YSZ/(La0.8Sr0.2)0.95MnO3-δ is fabricated and characterized. The LSTN-SDC microtubular substrate is prepared using an in-house built spinneret extrusion system in combination with modified phase inversion method, featuring radially well-aligned microchannels open at the inner surface. A thin YSZ electrolyte of ~15 μm and (La0.8Sr0.2)0.95MnO3-δ electrode of ~25 μm are then fabricated on the substrate, respectively. Upon reducing treatment, nickel is exsolved from LSTN grains and uniformly decorated onto grain surface as Ni nanoparticles, and therefore on inner surface of microchannels in the substrate. With CO/CO2 gas mixture as the fuel, the complicated electro-/chemical reactions are identified in the substrate electrode. The electrolysis process in combination with surface catalytic process of nanostructured electrode substrate leads to highly efficient CO production from CO2 with conversion efficiencies of well above 100%. The electrolysis also facilitates to regenerate surface catalytic functionality of nanostructured electrode substrate. The redox stability advantages of the cell are demonstrated in both alternative reduction (CO)/oxidation (air) atmospheric conditions and reversible operating mode.
Modeling the Charge and Discharge Behaviors of an AGM Lead-Acid Battery
Authors: Lee Jaewoo , Koo Boram , Shin Chee Burm
Published: February 2020

An absorbent glass mat (AGM) lead-acid battery is a type of valve-regulated lead-acid (VRLA) battery. An AGM lead-acid battery differs from a flooded lead-acid battery in that the sulfuric acid is absorbed in a very fine fiberglass mat, making the battery spill-proof. The leading advantages of AGM type are a higher specific power, lower internal resistance, five times faster charge speed than the flooded version, and the ability to deep cycle. AGM lead-acid batteries are found in high-end vehicles equipped with more electronic devices and making inroads into the start-stop function of cars. A validated mathematical model for the accurate prediction of the charge and discharge behaviors of an AGM lead-acid battery in real-world driving conditions is necessary to ensure that the battery can provide enough power for the rising number of electrical components.

In this work, a method of modeling the charge and discharge behaviors of an AGM lead-acid battery under various operating conditions is presented. This work adopts a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. By not computing the potential distribution of electrolyte phase and the transport phenomena of ionic species, the modeling method in this work cuts down considerable computation time in comparison with rigorous electrochemical models. The model is validated by comparing the modeling results with the experimental measurements.
Simulations of a New Flow Channel Design of Bipolar Plates for a Fuel Cell Type PEM By CFD
Authors: Castañeda Ulloa Locksley Fabiàn , Nava José Luis , Pérez-Segura Tzayam , Romero Tatiana
Published: February 2020

Nowadays, there is an increasing tendency towards renewable energy due to the limitation and pollution of fossil fuel. Among these energies, the fuel cell is a suitable technology with its high-power density converting chemical energy to electricity. Fuel cells are a highly efficient, environmentally friendly power source with broad applications in many industries including transportation as well as portable and stationary power generation, which will translate the chemical energy stored directly in the fuel and oxidizer into electrical energy. The proton exchange membrane fuel cell (PEMFC) is a useful type of fuel cell due to its high efficiency, high energy densities and low corrosion [1]. Other advantages of PEMFCs are their low operating temperature (40-90°) and planar geometry which allows many cells to be stacked together in order to obtain an appropriate size. Manufacturing and operating costs of this type of fuel cell can be reduced by optimizing the efficiency of fuel cells through detailed analysis of complex electrochemical and mass transport phenomena that occur within the cells [2]. It is very well known that the bipolar plate is an important component of the fuel cell, the design of the fuel cell is largely bipolar plate design, and especially the design of the flow field is a top priority [3]. In this context, this work deals with the simulation of a complete PEM fuel cell, emphasizing the novel design of the flow channels of the bipolar plates. The simulation was performed in a single cell configuration using the Navier-Stokes equations for the flow channels, the Brinkman equation for the gas diffusion layer, and for the mass transport the Maxwell-Stefan equations. Finally, for the simulation of the current distribution in the catalytic layer, the Butler-Volmer equation was adapted to the mass transport. The new design allowed a better dispersion of the gases inside the channels, avoiding water stagnation and increasing the efficiency of the fuel cell.

References

[1] Caglayan D.G., Sezgin B., Devrim Y., Eroglu I. Three-dimensional modeling of a high temperature polymer electrolyte membrane cell at different operation temperatures. Int. J. Hyd. Ener. 41 (2016) 10060-10070.

[2] Haghayegh M., Eikani M., Rowshanzamir S. Modeling and simulation of a proton exchange membrane fuel cell using computational fluid dynamics. Int. J. Hyd. Ener. 42 (2017) 21944-21954.

[3] Hermann A., Chaudhuri T., Spagnol P. Bipolar plates for PEM fuel cells: A review. Int. J. Hyd. Ener. 30 (2005) 1297-1302.
A New Developed Fluorinated Electrolyte for Anode-Free Lithium Metal Battery
Authors: Hagos Tesfaye Teka , Su Wei -Nien , Hwang Bing-Joe
Published: February 2020

Abstract

The glob is in need of efficient energy storage materials with an affordable cost, better energy density, safe and extended cycle life. To this end, scholars are investigating an alternative idea to boost the energy density, safety and minimize cost to satisfy the need of the society. One of the new ideas is the use of alternative design such as anode-free rechargeable lithium metal battery. In anode-free, the absence of Li+ host anode material reduces the cell weight and space required for the anode as a result; energy density of the cell will therefore be, significantly larger compared to the conventional Li-ion batteries. Nevertheless, realizing this anode-free battery in practical applications is still handicapped. The major reason for the failure of this system is depletion of the active Li and consumption of electrolyte solvents during repair of the solid electrolyte interphase. To mitigate this issue developing a functional electrolyte is therefore the key solution to bring it into practical application. Therefore, here we developed cost effective, highly fluorinated interphases forming new electrolyte solution of carbonate-ether mixed fluorinated electrolyte design with the standardized commercial salt LiPF6 which is stable at wider potential (2.5-4.5 V). The designed electrolyte suppresses dendrite growth, form conductive and stable LiF dominated solid electrolyte interface (SEI) for anode-free lithium metal battery using Cu‖LiNi0.3Mn0.3Co0.3O2. It shows stable cyclic performance with high average Coulombic efficiency > 98.7 % and high retention capacity for long cycles with 0.5 mA/cm2 current density both in the anode free system and NMC/MCMB full cell. The enhanced cycle life and well retained in capacity using the as-prepared electrolyte is mainly because of the synergistic effect of the partially fluorinated carbonated and ether based functional groups in which on contributes to the higher voltage and the other contributes to the higher efficiency. This is electrolyte combination is new and the best electrolyte ever reported for anode-free lithium metal battery to our knowledge.

Keywords: SEI
;
anode-free Lithium metal battery
;
carbonate-ether mixed solvent
; copper foil, Fluorinated Interphase
Exploring the Effect of Strong Complexing Agents As Electrolyte Additives on Anode Performance in Mg-Air Primary Batteries
Authors: Vaghefinazari Bahram , Hoeche Daniel , Lamaka Sviatlana V , Snihirova Darya , Wang Linqian , Deng Min , Zheludkevich Mikhail L
Published: February 2020

Mg-air primary batteries have drawn increasing attention recently due to their low cost, safety, and high theoretical specific power density. However, high self-corrosion rate and anode fouling during discharge (mainly due to the formation of Mg(OH)2/MgO) lead to particularly lower delivered voltage and utilization efficiency. Modification of the battery electrolyte chemistry plays a crucial role in tackling these shortcomings and improving battery performance. Remarkable enhancements to the Mg anode’s performance by addition of group of organic complexing agents in the Mg-air battery electrolyte has recently been reported [1]. In this study, the effect of two strong organic complexing agents (i.e. disodium 4,5-dihydroxy-1,3-benzenedisulfonate(Tiron) and Nitrilotriacetic acid(NTA)) as additives to the Mg-air battery electrolyte was investigated. Commercially pure magnesium with relatively high Fe impurity level (i.e. 220ppm) has been chosen as the anode material in order to have a better understanding of the interaction of the complexing agents with pure Mg and the common Fe impurity.

Half-cell measurements were conducted to evaluate the discharge performance of the anode in the presence of the complexing agents. The electrochemical and corrosion behavior were studied by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curve. The morphology of the anode surface after discharge was investigated by scanning electron microscope (SEM).

The results indicate that strong complexing agents can remarkably improve the discharge potential by activating the Mg anode surface and mitigating the high cathodic activity stemmed from Fe impurities. A possible downside of adding strong complexing agents is the tendency to accelerate the corrosion rate of the Mg anode. However, tuning the complexing agent concentration in the electrolyte can significantly improve the utilization efficiency at the expense of a slight decrease in the battery delivered voltage.

[1] D. Höche, S.V. Lamaka, B. Vaghefinazari, T. Braun, R.P. Petrauskas, M. Fichtner, M.L. Zheludkevich, Performance boost for primary magnesium cells using iron complexing agents as electrolyte additives, Scientific Reports, 8 (2018).
Plastic Crystal Polymer Electrolytes with Anion-Trapping Boron Moieties for Room Temperature All-Solid-State Sodium Batteries
Authors: Chen Suli , Che Haiying , Feng Fan , Yin Yimei , Ma Zi-Feng
Published: February 2020

Sodium-ion batteries (SIBs) have been considered as promising alternatives to lithium-ion batteries (LIBs) particularly in large scale electric energy storage applications for renewable energy and grid due to low cost and the huge abundance of sodium resources. However, increasing safety issues caused by the use of conventional organic liquid electrolytes (LEs) greatly hinder the commercial application of SIBs in electric vehicles or hybrid electric vehicles [1]. Replacing LEs with solid electrolytes (SEs) can inherently address such safety problems. However, it is a compelling challenge to develop SEs with superior room-temperature ionic conductivity, high ion transference number, considerable mechanical property, and low electrolyte/electrode interfacial resistance [2]. Recently, we developed a new type of nonwoven supported plastic crystal polymer electrolyte containing anion-trapping boron moieties (B-PCPE), which prepared by in situ growth method using UV-curing technique. In addition, the plastic crystal electrolyte modified electrodes were also designed to reduce interfacial resistance. The B-PCPE shows excellent room temperature ionic conductivity (0.36 mS/cm) and greatly enhanced sodium transference number (0.62) due to the presence of anion-trapping boron moieties. All-solid-state SIB assembled using the B-PCPE with anion acceptor exhibits excellent cycle performance and rate capability at room temperature. The cell delivers first discharge capacity of 104.8 mAh/g with Coulombic efficiency of 94.1% and the capacity retention is about 80.1% after 120 cycles at 0.1 C. We believe this B-PCPE is a promising candidate for practical application and our work provides a new perspective to design high-performance solid electrolyte for ambient-temperature all-solid-state batteries with exceptional rate capability and cycle stability.

References

[1] H. Che, S Chen, Y. Xie, H. Wang, K. Amine, X. Liao, Z-F. Ma, Energ. Environ. Sci., 10, 1075(2017)

[2] Z. Y. Lin, X. Y. Guo, H. J. Yu, Nano Energy, 41, 646( 2017)