bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of Internal Structural of 3D Printed Shape Memory Gels
Authors: Shiblee MD Nahin Islam , Rahman MD Sazzadur , Ahmed Kumkum , Kabir M. Hasnat , Khosla Ajit , Furukawa Hidemitsu
Published: February 2020

Understanding the internal structure of the gels is important to comprehend their physico-chemical properties and propose better utilization in practical application. The scanning microscopic light scattering (SMILS) is one of the powerful tools to nondestructively characterize the internal structure of gels. The SMILS is a typical dynamic light scattering (DLS) system, which can be used to characterize the internal structure of gels by observing the diffusion process [1]. In our previous study we studied internal structures of Poly (N-N-dimethylacrylamide (PDMAAm) gels and different inter-crosslinking network (ICN) gels and compared their crosslinking density with ionic gels [2]. We also determined the soft to hard transition temperature of PDMAAm-co Stearyl acrylate (SA) shape memory gels SMGs prepared by mold techniques by carrying out temperature dependent SMILS measurements [3].

In this work, we present the structural analysis of 3D printed transparent SMGs containing two different hydrophobic crystalline monomers SA and Lauryl acrylate (LA) fabricated by optical stereolithography technique. By SMILS we can obtain a time- and space-averaged correlation function i.e., an ensemble-averaged correlation function to overcome the inhomogeneous media. For each sample, the time-averaged homodyne correlation functions g(2)(q,τ) were determined at several points, where q is scattering vector and τ is correlation time. Then the ensemble-averaged correlation function g(1)(q,τ) was calculated. Thus, the characteristic size of diffusing objects (mesh size) ξ can be estimated from the Einstein-Stokes formula. In the measurement of the SMGs, we controlled the angle of PMT and relaxation time distribution was calculated for every angle. We have correlated their internal structures with mechanical properties to understand their internal structures and made justified assumption on their structural homogeneities.

H., Horie, K., Nozaki, R., Okada, M. Phys Rev E 68:031406-1-14 (2003)

Ahmed, K., Watanabe, Y., Higashihara, T. Arafune, H. Kamijo, T., Morinaga, T. Sato, T., Makino, M. Kawakami, M., Furukawa, H. Microsyst Technol., 22, 17 (2016)

Kabir, M., H., Gong, J., Watanabe, Y., Makino, M., Furukawa, H.

Lett., 108, 239–242 (2013)
Hydrogel Adhesion Utilizing Stimuli-Responsive Wrinkling Films
Authors: Kato Masatoshi , Asoh Taka-Aki , Uyama Hiroshi
Published: February 2020

Wrinkle structures are often observed at the surface and/or interface of materials and have a role for gaining surface area. Recently, we have found that wrinkle structure at the adhesive interface of gels strengthen the adhesion strength. Then we hypothesize that adhesion can be controlled by formation and deformation of wrinkle structures. We fabricated a stimuli-responsive wrinkling films by using thremoresponsive polymers. Adhesion and detachment of hydrogels can be regulated by formation/deformation of wrinkle structure in response to temperatures.
(Keynote) Shear-Thinning and Self-Assembling Polymer Hydrogels for Drug-Induced Tissue Regeneration
Authors: Messersmith Phillip
Published: February 2020

While amphibians regenerate lost appendages spontaneously, mammals generally scar over the injury site via wound repair. Inspired by the spontaneous healing trait of amphibians, we are developing self-assembling polymer prodrugs for delivery of a HIF1a agonist. The polymers self-assemble into filament-like nanostructures as determined by small-angle x-ray scattering (SAXS), driven by the hydrophobic nature of the conjugated drug. Entanglement of nanofibrils result in a viscoelastic, shear-thinning material, suitable for liquifying during passage through a needle. Subcutaneous injection of drug-hydrogel resulted in enhanced regenerative wound healing in non-regenerative mice, in a manner that emulates the basic elements of amphibian regeneration. These approaches offer new opportunities for delivery of tissue regenerative therapeutic drugs.
TEM Observation of Nano-Scale Hydrogel Network Structure
Authors: Kiyama Ryuji , Nonoyama Takayuki , Nakajima Tasuku , Kurokawa Takayuki , Gong Jian Ping
Published: February 2020

Hydrogel, containing large amount of water inside its polymer network, is one of the most attractive biomaterials, because of its similarities with living tissues such as, high water content, low friction and flexibility. These unique features come from complicated polymer network structure, and until now great effort have been put in to clarify nano scale structure of hydrogel. Especially, many researchers tried to investigate by using scattering techniques. However, scattering data just presents limited information in reciprocal space and “real” polymer network structure is still not well understood due to difficulty on direct observation of hydrogel polymer.

In this study, we adopt an idea to stain polymer network by using inhomogeneous nucleation, nucleation starts from the functional group of additive. If we carried out inhomogeneous nucleation in the hydrogel, mineral crystals easily forms complex with hydrogel network and this mineral distribution should represent the original polymer structure. Therefore, the purpose of this study is to stain hydrogel polymer network with mineral and to observe its nano-scale structure by using transmission electron microscope (TEM).

　Double network hydrogel was synthesized by two step UV radical polymerization.1 2-acrylamido-2-methyl propanesulfonic acid (AMPS), which contains sulfonic functional group, was used for 1st polymer network. Then, mineral bernalite (Fe(OH)3), whose nucleation accelerates by sulfonic group, was mineralized into DN gel. Fig.1 shows TEM image of mineralized DN gel and its schematic image. Nano scale hydrogel polymer network structure was successfully observed and this structure well agreed with previous prediction from neutron scattering method. This is the world’s first direct observation of polymer network. Mineralized crystal size was several nm in diameter, which is same scale of polymer blob. It indicates that we observed mineral crystals surrounded by individual polymer blobs. The detailed results will be presented in conference. In conclusion, we succeeded direct observation of hydrogel polymer network using TEM. This is a very challenging study not only for understanding hydrogel, but also for visualization polymer network, which is one of biggest dream of polymer scientists.

References

[1] J.P. Gong et al., Advanced Materials, 2003, 15, 1155–1158.

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Synthesis and Multi Stimuli-Responsive Properties of Amino Acid-Based Nanoparticles with Fluorescent Cross-Linked Cores
Authors: Kataoka Keita , Chen-Tsyr Lo , Nakabayashi Kazuhiro , Mori Hideharu
Published: February 2020

Stimuli-responsive nanoparticles with fluorescent cross-linked cores were prepared by in-situ Suzuki-coupling reactions of amino acid-based block copolymers using dithiophene- and fluorene-based diboronic acids. Block copolymers synthesized by RAFT polymerization of threonine-containing monomer and 4-bromophenyl vinyl sulfide were used for the self-assembly in a selective solvent and subsequent cross-linking reactions. The formation of stable core cross-linked nanoparticles with stimuli-responsive shell derived from threonine was confirmed by DLS, UV-vis, fluorescence, and CD measurements. Multi stimuli-responsive photophysical properties, depending on pH, salt, urea, and metal species, were evaluated in various organic and aqueous solvents.

Figure 1
(Invited) Flexible and Printed Electronics Technology/Market Trends
Authors: Shepherd Clay
Published: February 2020

This presentation will review the more significant domestic and overseas trends in flexible & printed electronics technology and markets, with an emphasis on flexible/ wearable sensor applications.
(Invited) Flexible and Printable Organic Solar Cells for High-Performance and Stable Operation
Authors: Fukuda Kenjiro , Someya Takao
Published: February 2020

Abstract

Efficient, stable and flexible organic solar cells can deliver energy in an environmental friendly way and offer great potentials as portable and compact power sources. All state-of-the-art organic solar cells are at present processed on rigid substrates with limited active area. Attempts to process organic solar cells on flexible plastics using printing technology often result in inferior performance, due to imperfect interface, undesired delamination or intricate processing. We are trying to solve these problems from various view point By checking each material itself and process, both high power conversion efficiency and high stability can be achieved. In this talk, we will discuss how to achieve high efficient and water-proof [1], thermally stable [2], and mechanical robust [3] solar cells on flexible substrates.

Jinno, H. et al.
Nat. Energy
2, 780–785 (2017).

Xu, X. et al. doi:10.1073/pnas.1801187115 (2018)

Jiang, Z. et al., Adv. Mater. Accepted.

Figure 1
Modeling and Analytical Studies of an Ink-Jet Printed Sensing Framework for Measuring Sub-Soil Nitrate
Authors: Burton Lamar Kendrell , Fernandez Renny E , Wen Wujie , Bhansali Shekhar
Published: February 2020

We have demonstrated ink-jet printed IoT sensor sheets capable of quantifying long-term soil nitrate concentration as shown in Fig. 1a. However, our previous data indicates that long routing lines contribute to lossy signals, noise, and electrode cross-talk within the sensor sheet. Using this current version of the sensor sheets leads to following challenges: 1) unbalanced sensing performance at different locations. Sensors further away from the power source report over 45% signal loss and large sensing current variation due to the unbalanced signal routing as seen in Fig. 1b. 2) Noisy sensing incurred by the signal crosstalk. As Fig.1c shows, the interference from neighboring sensors can largely deviate the sensing of a target sensor. 3) Inaccurate sub-soil nitrate analysis because of imperfect sensing results from failed or noisy sensors. This paper focuses on the development of mathematical models to quantify the sensing crosstalk among targeted sensors and other idle sensors for high-accurate sensing, and use the models as guides for robust VLSI sensor array design and routing architecture. A unique aspect of our approach is to use sensor cross-talk as a technique to identify sensor failures. The simple linear and nonlinear models, as well as advanced 2pi model used to measure the coupling between victim and aggressor nets in VLSI physical design, will be implemented on the ink-jet printed sensor sheets.

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(Invited) The Challenge of Shaping Ideas into Applications: The Multi-Competences Approach in Industrial Innovation
Authors: Albunia Alexandra Romina , Gloger Dietrich , Hristov Velichko , Liu Yi , Stockreiter Wolfgang
Published: February 2020

The number of application fields of polymeric materials has impressively broadened over the few decades following the implementation of industrial polymerisation production processes. Synthesis of new polymers or a more advanced control of the molecular design of polyolefinic materials has often driven the technological innovations that are at the base of our modern society.

The production of polymer based goods at industrial level is an extraordinary example of multidisciplinary collaboration. Either starting from designing new materials, or starting from the property requirement of the end application, the original idea needs to develop based on the knowledge of the material properties, of the technology enabling its synthesis, and of the processing conditions to transform it into the required application. In fact, driving the innovation of polymeric materials and applications requires the understanding of the structure-property relationships along the whole value chain and a sound knowledge of physical and chemical processes at many different scales.

In this perspective, new developments pull for a closer cooperation of experts from different fields and for a smarter use of the resources, including a systematic design of experiments, the increased access to modelling tools to understand and predict processes and phenomena, and a better use of the full set of data available (digitalisation).

Recent material developments have been possible in Borealis following such multi competences approach and some selected cases will be presented.

It will be shown, for example, how the development of polypropylene fiber reinforced materials, and in particular long glass fibers (PP-LGF), is based on the ability to monitor the major parameters correlating with the mechanical performance, namely the final fibre length, the distribution, and the orientation, throughout production and conversion of reinforced, injection moulded polymer parts for automotive applications. The possibility of material modelling for understanding how to influences fiber length during production and conversion allowed to establish a guideline of best practice to get the maximum out PP-LGF.

It will be also shown how modelling of film production process parameters can be used for understanding how to influence the structure and morphology generated in thin films, and how this might be correlated to the electrical insulation and anti-cling properties of the BOPP (biaxially oriented polypropylene) dielectric layer in capacitors.

As third example, the correlation between multimodal polymer design, crystallisation conditions and pressure pipe performance will be presented, discussing how modelling the entangled polymer network would help in predicting the pressure pipe life time.
Temperature Distribution Analysis of Viscoelastic Fluid Stirred By Single Triangular Rotor
Authors: KC Indra Bahadur , Higashi Kosuke , Noguchi Yuki , Kawaguchi Tatsuya , Satoh Isao , Saito Takushi
Published: February 2020

During rubber manufacturing, rubber is mixed with compounding agents through kneading process. Kneading results to generation of very high shear heat. High heat sometime leads to burnt and low quality rubber. Also this high heat changes rubber from solid to viscoelastic form. In order to analyze temperature distribution of viscoelastic fluid, CMC (Carboxyl Methyl Cellulose) have been prepared. The solution was kneaded using simple single triangular rotor. Compared to rubber, shear heat in CMC solution is very low. Thus to compensate shear heat, external heater has been used. Temperature measurement was done using LIF (Laser Induced Fluorescence) technique. Kneading was done under different rotor speed and it was found that higher rotor speed resulted into proper temperature distribution. Beside, at the tip of the rotor, high temperature fluid was accumulated. When compared to normal viscous fluid (Glycerol), CMC showed different shape of temperature field at rotor`s tip.
Fabrication of Line & Space Structure and Wiring on 3D Surface Features with Imprinting Process
Authors: Ota Shogo , Kurose Takashi , Ito Hiroshi
Published: February 2020

In recent years, electronic devices made by polymers with wiring materials are widely used, such as FPC (Flexible Printed Circuit) in a PC (Personal Computer), and smartphones. Fine Pitch Wiring technologies on 3D objects are needed for coming IoT(Internet of Things) trends. Therefore, in this research, we conducted a fundamental study of the low-cost replication process with etching less wiring method in order to replicate microstructure on the curved polymer surfaces by using the hybrid nanoimprint technology. The first imprinting step was carried out to produce the intermediate mold on COP (Cyclic Olefin Polymer) surface by thermal nanoimprint process. The aluminum mold with a concavo-convex structure called L/S (Line & Space; concave width of 500 µm, concave depth of 100 µm) was used. The obtained intermediate structure was coated with UV (Ultraviolet) curable resin and it was applied to the 3D substrate (curved surface region: lens shape) having planar region and curved surface region as shown in Fig. 1. In this step, UV imprinting was applied with the pressure of 5 MPa and UV irradiation time of 300 seconds to transfer the L/S structure to the 3D substrate. Thereafter, the silver nanoink was dropped and filled in the concave portion of the L/S structure using a dispenser and sintered at 160 oC for 1 hour. SEM (Scanning Electron Microscope) image revealed that the 3D structure can be precisely transferred on the curved surface by using this hybrid nanoimprint technology (See Fig. 2). In Fig. 3, the transfer rates in the planar region (flat) and curved region were 100 and 60%, respectively. It is considered that the liquid UV curable resin may flow downward from the upper part to the lower part along the inclination of the substrate during the crimping and curing steps, resulting in the decrease in filling amount from the intermediate mold structure. The L/S patterned wired with silver nanoink is shown in Fig. 4. This result proposes that the hybrid nanoimprint technology is considered to be an effective method for the replication of wiring on the curved surface.

Figure 1
Viscoelasticity of Short Polymer Melts from Atomistic Simulations
Authors: David Alessio , De Nicola Antonio , Milano Giuseppe , Raos Guido
Published: February 2020

Tube theories provide a well-established description of the dynamics and viscoelasticity of polymer melts. Their equations are quite general, but they contain system-specific parameters such as the monomer friction coefficient and the packing length. These depend on the chemical structure of the polymer and they are typically obtained by experiment. In the long term, it would be desirable to be obtain these by computational methods, for example in order to allow the “in silico” screening of new materials and the rational formulation of new polymer blends.

Despite much recent progress, atomistic Molecular Dynamics (MD) simulations cannot yet be applied to simulate directly the behavior of entangled polymers. This is mostly due to the disparity between the typical times scales of the simulations and the relaxation times of the systems (microseconds versus seconds, as a rough order of magnitude). Given these limitations, our aim is to explore the applicability of atomistic MD simulations to investigate relatively short polymer melts (below the entanglement length) and extract parameters which are relevant for the viscoelasticity of polymer melts. In principle, the linear response of these systems can be extracted from ordinary equilibrium MD simulations (see for example the Green-Kubo relationship, linking the viscosity to the time-integral of the stress autocorrelation function). In addition, different variants of the Non-Equilibrium Molecular Dynamics (NEMD) method can be used to impose a shear deformation and record the resulting stress, thus obtaining the viscosity from their ratio (including its non-Newtonian shear-dependence). Both classes of methods present advantages and potential pitfalls, and at this stage it is important to develop a feeling for them. In this communication will present a comparison of these methods, using polyethylene, polypropylene and poly(methylmetacrylate) as benchmark systems in order to highlight their relative strengths and weaknesses.
(Invited) Modeling Morphology Distribution in Injection Molded Polypropylene Parts
Authors: Pantani Roberto , Liparoti Sara , Speranza Vito , Titomanlio Giuseppe
Published: February 2020

The UNISA code, a software for the simulation of injection molding developed at the University of Salerno, considers a series of specific models to consider several aspects of the mutual effect of flow and crystallinity: the effects of temperature, pressure and flow on relaxation times, the effect of crystallinity on viscosity, the effect of flow on nucleation density and spherulitic growth rate. Each of the effects mentioned above was experimentally analyzed and described by a model for the iPP grade considered in this work. The combination of all these specific models becomes a model for the morphology evolution during polymer processing.

In order to verify the accuracy of the predictions, a series of injection molding tests were obtained applying a system which allows to control the cavity surface temperatures. This technique allows to keep, for assigned time intervals, the cavity surface temperature at intermediate values between injection and cooling channels temperatures. A modulation of the level of the cavity surface temperature and of the time, it was kept active, allowed to control the final sample morphology all the way from the complexity of a standard injection molded part down to a completely (skin and shear layers free) spherulitic structure.

The fibrillar layer morphology was related to the achievement of critical values of both the molecular stretch and the mechanical work, the latter being performed after the achievement of the critical molecular stretch. The dependence of the morphological layers (skin, shear, spherulitic layers, the latter including the transition from the shear zone) thicknesses upon the heating conditions was satisfactorily described by the models adopted.
Smoothed Boundary Method and Its Application to Electrochemical Systems
Authors: Choe Min-Ju , Yu Hui-Chia , Kazemiabnavi Saeed , Enrique Raul , Thornton Katsuyo
Published: February 2020

The morphological complexity and dynamical nature of microstructures make conventional continuum-level simulations, which often involve interfacial boundary conditions, challenging. In this talk, we will present the Smoothed Boundary Method (SBM), which uses phase-field-like domain parameters to define the bulk domains, where the partial differential equations are solved, and the interfaces, where the boundary conditions are imposed. This method is straightforward in derivation and simple in numerical implementation. As a diffuse interface approach, the SBM circumvents the need for structural meshing of the interfaces, which are difficult when the interfacial morphologies are complex. Thus, the SBM is a powerful tool for image-based three-dimensional microstructural simulations. A variety of partial differential equations can be reformulated using the SBM, including those that govern mass transport, stress-strain responses, phase transformations, and electrochemistry. Applications to batteries are highlighted.
(Invited) Reducing the Photon Energy Loss in Polymer Solar Cells
Authors: Osaka Itaru
Published: February 2020

A crucial issue facing polymer-based solar cells (PSCs) is how to manage the energetics of the polymer/fullerene blends to maximize short-circuit current density (J
SC) and open-circuit voltage (V
OC) at the same time and thus the power conversion efficiency (PCE). A key to resolving the issue is to reduce the relatively large photon energy loss (E
loss), which is defined by E
g– eV
OC, where E
gis the optical bandgap of the material. One example is a semiconducting polymer based on naphthobisoxadiazole (PNOz4T). PNOz4T, with a narrow E
gof 1.52 eV, led to high V
OCs of approximately 1 V and high PCEs of more than 8%, when combined with PC71BM. As a result, the E
losswas found to be 0.52–0.56 eV, which is much smaller than that of typical polymer systems (0.7–1.0 eV) and approaches the values for inorganic and perovskite solar cells. The small E
lossis due to the very small energy offset that is a driving force for the photoinduced charge separation, i.e., the offset of the LUMO energy levels between PNOz4T and PC71BM was 0.1 eV. It is also interesting to note that PCEs of the PNOz4T system are the highest values among the PSCs, that used fullerene derivatives as the electron acceptor, having such small E
losss. We also show ternary blend system with well controlled energetic alignment can give small E
losss with less than 0.5 eV.
(Invited) Phenanthro[1,2-B:8,7-B’]Dithiophene (PDT): Application to Organic Photovoltaics
Authors: Nishihara Yasushi
Published: February 2020

The new phenacene-type molecule, phenanthro[1,2-b:8,7-b']dithiophene (PDT) have been designed and synthesized. Moreover, we synthesized polymers containing a PDT core in the polymer backbone. These PDT-based polymers have some superior features, including strong intermolecular interaction, high thermal stability, deep HOMO energy levels, and dense packing structure in their solid state. The solar cell devices using PDT-isoindigo (IID) copolymer or PDT-benzothiadiazole (BT) exhibited high power conversion efficiency (PCE) with 5.28% and 6.56%, respectively. In particular, PDT-BT copolymers formed a desirable face-on orientation, which can promote the efficient carrier transport in solar cells, reading to high PCE. From DSC measurements, P3HT, which has been widely studied for various electronics devices, showed phase transition peak around 200 ºC in heating and cooling processes. On the other hand, these polymers showed no peak ascribed to a phase transition in the range of 50-250 ºC. The thermal decomposition temperatures estimated by TG/DTA was higher than 300 ºC, which is inferior to that of P3HT. These results show that the devices composed of these polymers maintain the solid state, and thus the device performances. Furthermore, these polymers are stable than P3HT. The HOMO level measured by PYS (photoelectron yield spectroscopy) shifted to a more negative side upon storage in air, but the degree of a change was smaller than that of P3HT. This indicates that the device composed of these polymers may keep the good performance longer than that composed of P3HT.

Figure 1
Deep Red Phosphors Based on 3d Transition Metals for Energy Conversion from UV to Visible Rays
Authors: Matsushima Yuta , Kobayashi Riho , Tamura Hideto , Kamada Yuki , Sato Kazuya , Sato Chika , Kakihana Masato
Published: February 2020

Reflecting the recent increasing concern about an energy issue, solar cells have been developing for several decades. Silicon is the major solar cell material with the band gap energy of ~1.17 eV. The optical absorption band corresponds to ~1100 nm and the radiations with wavelengths shorter than it are absorbed to generate photovoltaic power. The spectral sensitivity characteristics do not match the solar spectrum and energy conversion of the UV and blue radiations to longer wavelength side will improve further the efficiency of the Si solar cells. This work presents deep-red phosphors based on lithium aluminates and related compounds using 3d transition metals as the luminescent center. Deep-red emission by 3d transition metal phosphors has been much attracted because it can be attained with quite few rare-earth phosphors.

LiAlO2 and LiAl5O8 were chosen for phosphor host materials, which were prepared through a solid state reaction method from lithium and aluminum sources of LiF and Al2O3. The luminescent center of Fe3+ or Mn4+ was added in a form of Fe(NO3)3·9H2O or MnO2. The mixed powder in a Pt crucible was heat treated in air at 800-1300 °C.

It was found that the lithium source LiF brought several unusual phases in the products. Metastable α-LiAlO2 appeared at 800 °C and below when a mixture of LiF and Al2O3 was treated with an excess a LiF condition of LiF/Al = 3. It was good contrast to the fact that the a-phase obscurely crystalizes at 500-700°C with the broad peaks when LiOH·H2O was used as a lithium source. α-LiAlO2 transformed to stable γ-LiAlO2 at 800 °C or above. On the other hand, a mixture at LiF : Al2O3 = 1 : 2 resulted in a novel host material with an unknown composition. Although the XRD pattern itself has been reported as JCPDS #38-610, the details of the crystal structure and the actual composition have never been disclosed. The composition estimated in this work with EDS and XPS was Al4LiF0.1O6.45. A disordered spinel structure was assigned for ALFO by Rietveld analysis.

The luminescent spectra are compared among α-LiAlO2:Fe3+, γ-LiAlO2:Fe3+ and ALFO:Fe3+ in Fig. 1, and between LiAl5O8:Mn4+ and ALFO:Mn4+ in Fig. 2. α-LiAlO2:Fe3+, γ-LiAlO2:Fe3+ and ALFO:Fe3+ showed rather broad PL with the peak tops between 650 and 800 nm. Their peak positions are slightly different to each other and the emission peak of ALFO:Fe3+ resides at the shortest wavelength side. The excitation bands are in the UV region and the maxima are around 250 nm. On the contrary, the Mn4+ luminescent center changes its properties depending on the host materials. Deep red emission at 661 nm was much enhanced in ALFO:Mn4+, whereas LiAl5O8:Mn4+ exhibited only faint PL.

Acknowledgement: This work was performed under the Cooperative Research Program of "Network Joint Research Center for Materials and Devices (20181151).

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(Invited) Development of Concentration Profile of Li+ Ion Accompanied with Electrodeposition of Li Metal in Solvated Ionic Liquid
Authors: Nishikawa Kei , Saitoh Takaki , Matsushima Hisayoshi , Ueda Mikito
Published: February 2020

Li metal is promising anode candidate for next-generation batteries because Li metal has very large specific capacity and Li/Li+ potential is the lowest. It is indispensable to control the surface morphological variation during cycles in order to utilize Li metal anode in next-generation batteries. In this study, the morphological variation of Li metal electrode in the electrodeposition is discussed from the viewpoint of Li+ ionic mass transfer rate in the vicinity of the electrode surface. In general, the metal electrodeposition and the morphology of electrodeposits are strongly affected by the electrode surface concentration. However, there are only a few researches focused on the relationship between the morphological variations of electrodeposited Li metal and the ionic mass transfer phenomenon. A digital holographic microscope (DHM) was utilized in order to visualize the Li+ concentration profile during the electrodeposition of Li metal. Our previous researches used a holographic interferometry to in-situ measure the surface concentration and concentration boundary layer thickness during the electrodeposition of Li metal. The principle of the technique is same, but the resolution of DHM was drastically improved. Figure 1 shows the DHM image in solvated ionic liquid electrolyte (LiTFSA:tetraglyme(G4) = 1:1). A working electrode was Cu plate, and a counter electrode was Li metal. Applied current density was 3.0 mA cm-2. The image was recorded at 100 seconds after the electrodeposition started. The color variation indicates the Li+ concentration profile near the working electrode, and the image shows that very uniform concentration profile was formed in this case (the precursor of Li dendrite was not detected.). Not only Li+ surface concentration but also concentration boundary layer thickness are focused to discuss the Li+ ionic mass transfer phenomenon. Especially, solvated ionic liquids are new electrolytes for batteries and then it is very important to understand the ionic mass transfer in the solvated ionic liquids. We would like to discuss the relationship between the morphological variations of electrodeposited Li metal and the developing the concentration profile in solvated ionic liquids systems.

Figure 1
Sustainable Process for Carbon Nano Onions from Flaxseed Oil for High-Performance Supercapacitors
Authors: Kim TaeYoung , Tripathi Kumud Malika
Published: February 2020

One of the global key challenge for our society is energy crisis and increasing environmental pollution arises from excessive consumption of fossil fuels. There is an increasing demand for long-term sustainable and durable energy storage devices with tremendous applications in electric, car power supply and wearable electronics. This requires simple, economical and green techniques for the fabrication of active materials to be used in energy storage devices. Supercapacaitor (SCs) as a promising energy storage device which uses electrical double layer (EDL) composed by electrolyte ions and charges on electrode materials surface, and the physisorption offer moderate energy density, high power density, stable life cycle and pollution free operation. With consideration to SCs performance depending on the physical interface, many efforts have been focused to improve electrochemical performance of SCs with high capacitance and higher voltage operated with electrolytes. Herein, we try to address both these critical issues exploring sustainable synthesis of carbon nano onions (CNOs) as the electrode material to fabricate high performance and durable SCs. An environmental-friendly flame synthesis approach was used for facile and large scale synthesis of CNOs for application in high-performance supercapacitors.
(Keynote) A New Era for Hydrocarbon, Solid Polymer Electrolyte Membranes
Authors: Holdcroft Steven
Published: February 2020

Full scale commercialization of Proton Exchange Membrane Fuel Cells (PEMFCs) is imminent yet fundamental knowledge in specialized areas is still required in order to resolve persistent technical barriers associated with high materials costs and limited reliability, versatility, and performance.

Perfluorinated proton-exchange polymers form the basis of standard high-performance PEMFCs but difficult synthetic chemistry hampers further materials development. Hydrocarbon proton-exchange materials, on the other hand, are founded on well-established and versatile synthetic chemistry that allows for rapid materials development, and offer a less expensive alternative to perfluorinated polymers. In this presentation, the evolution and properties of unique proton-conducting polymers will be described.

References:

• “Structurally-Defined, Sulfo-Phenylated, Oligophenylenes and Polyphenylenes”, J. Am. Chem. Soc, 137 (2015) 12223-12226.

• “Alcohol-Soluble, Sulfonated Poly(arylene ether)s: Investigation of Hydrocarbon Ionomers for Proton Exchange Membrane Fuel Cell Catalyst Layers”, J. Electrochem. Soc., 162 (2015) F513-F518.

Acknowledgements: T.J.G. Skalski, M. Adamski, M. Killer, E. Schibli, A. Hohenadel, B. Britton, B. Frisken, T. J. Peckham
(Invited) Organic Molecules for Redox Flow Batteries
Authors: Chen Qing
Published: February 2020

The need for grid-scale electricity storage demands cost-effectiveness and durability beyond the reach of current Li-ion battery technologies. Redox flow batteries (RFB) decouple energy from power that promise low cost for long discharge duration as required for load shifting, and they offer long cycle lives as no phase change occurs in the electrodes. However, the most mature RFB technology relies on vanadium salts, whose high and volatile cost threatens its practicality. Among alternative redox couples, organic molecules are emerging with a high promise for their projected low cost and versatility in terms of providing various properties desired in a RFB. In this talk, I will focus the attention on the use of quinone molecules for aqueous RFBs. I will start with molecular selection and design strategies that have been successfully applied to tune the redox potential, the solubility, and the stability of quinones. I will then discuss the engineering aspects of delivering the promise of quinone molecules in stable, high-performance RFBs. I hope that the talk will provide a comprehensive overview of the application of organic molecules in RFBs and stimulate new ideas for exploiting organic materials for energy storage.
(Invited) Understanding the Dynamics in Battery Electrodes: Synergies of Experiments and Simulations
Authors: Thornton Katsuyo
Published: February 2020

Mechanisms underlying charge/discharge of batteries are difficult to elucidate because of the complex interplay of electrochemistry, material thermodynamics, and transport (diffusion and phase transformations). The interpretation of experimental data is challenging due to the inhomogeneity within the components, especially within electrode composites. Thus, integration of experiments and simulations is essential in elucidating the mechanisms underlying experimentally observed phenomena. In this talk, we will present works in which simulations performed in concert with experiments led to key insights in how material parameters (e. g., kinetic coefficients, thermodynamic data, and microstructural morphologies) influence the charge/discharge behavior of a battery cell. Comparisons between simulations and experiments can be used to determine parameters that are difficult to measure, as well as to verify or invalidate hypotheses explaining the behavior.
Electrodeposition of Zn-Terephthalate MOF Thin Films
Authors: Nakamura Tenshou , Ueda Shotaro , Uda Kyota , Tsuda Yuki , Hirai Yuji , Sun He , Yoshida Tsukasa
Published: February 2020

Metal organic flamework (MOF) is a class of inorganic / organic compound whose crystalline structure is made by bridging inorganic ions with organic ligands. Due to its open porous structure, special functionalities are anticipated in applications such as sensors, catalysis and batteries. Variation of MOFs is almost unlimited, not only by choice of building blocks but also by change of composition and crystalline structure.

We have recently reported microwave assisted hydrothermal synthesis of MOFs with various layered structures, in which Zn2+ ions are bridged by terephthalic acid (TPA). These Zn-TPA MOFs exhibited proton-selective reversible redox reactions, suggesting their usefulness in membrane-free redox batteries.

On the other hand, we have established a method to electrochemically self-assemble ZnO / organic dye hybrid thin films. When there is a favorable chemistry between inorganic and organic constituents, their hybrid nanostructures are spontaneously formed during electrolysis. Self-assembly of Zn-TPA MOFs can therefore be expected by minor addition of TPA into the bath for cathodic electrodeposition of ZnO.

Potentiostatic electrolysis at -1.0 V (vs. Ag/AgCl) in O2-saturated aqueous electrolyte containing 5 mM ZnCl2 and TPA up to 500 μM resulted in gradual decrease of cathodic current of oxygen reduction current (Fig. 1). Strong passivation occurs when TPA > 75 μM to reduce the steady-state current down to ca. 0.1 mA cm-2, as compared to the O2 transport limit (ca. 1 mA cm-2 for Zn2+ + O2 + H2O + 2e- → ZnO + H2O2). Minor addition of TPA at 5 μM resulted in appearance of thin flake-like deposits together with tiny grains of ZnO, which then changes into entire coverage of the FTO-glass substrate with the flakes at 200 μM while ZnO grains disappear (Fig. 2). X-ray diffraction (XRD) patterns of the deposits revealed that the flakes are those of Zn-TPA layered MOF in a Zn3(OH)4(TPA)•6H2O composition.

The passivation is obviously caused by high electrochemical resistance of the electrodeposited MOF towards O2 reduction, making it difficult to obtain thick MOF films for battery applications. Exploring the conditions to promote continuous electrochemical growth of MOF is under way.

Figure 1
(Invited) Multimodal Enzymatic Sensing for Continuous Wound Monitoring
Authors: RoyChoudhury Sohini , Umasankar Yogeswaran , Bhansali Shekhar
Published: February 2020

Present wound care techniques are primarily visual and entail repeated visits to the clinics. A biosensing system that can provide direct longitudinal measures of lesion healing and tissue recovery can assist to bridge the time between occurrence of a wound and its effective management. The correlation of purine precursors with wounds is well established. Products of the purine metabolic pathway, xanthine and uric acid, are known to have high correlation with wound chronicity and healing. With increased breakdown of cells, the concentrations of these analytes reportedly increase with increased reactive oxygen species (ROS) to promote healing. This work explores the biochemical pathway of purine metabolism and provides a method for continuous monitoring of healing on a multimodal sensing platform. This system employs the enzymes xanthine oxidase and uricase, known to be stable at an alkaline pH, for specific detection of the respective analytes. pH of a wound changes from alkaline to acidic as a wound heals, shifting the potential of detection. This has been addressed by the integration of a pH sensor on the same platform, enabling real-time calibration and providing a thorough assessment of underlying tissue recovery.
(Invited) Hydrothermal Growth of Zinc Oxide (ZnO) Nanorods and Structural and Optical Studies for Soil pH Measurement Applications
Authors: Naveen Kumar S K , Akshaya Kumar A , Aniley Almaw Ayele , Bhansali Shekhar , Fernandez Renny E
Published: February 2020

Zinc Oxide (ZnO) nanorods (NRs) are developed by a hydrothermal growing method using zinc acetate as the precursor material. The synthesized ZnO particle solution deposited on the Aluminum and Glass substrate by using a spin coating and thermal evaporation method. ZnO nanoparticle layer is treated for hydrothermal growing procedure and further annealing at high temperature to obtain uniform ZnO NRs. The structural and optical properties of the ZnO NRs are examined with field emission scanning electron microscopy with Energy Dispersive Spectrometer, X-ray diffraction meter and UV visible spectrometer. The crystal qualities, grain size, diameter, and optical bandgap of the ZnO NRs were affected by the type of solvent and substrates used. The developed ZnO NRs thin film structure has high potential application in soil pH measurement.

Keywords: ZnO NRs; Spin Coating; Thermal Evaporation; FESEM/EDS; XRD; UV Visible spectrometer

Figure 1
Ga Doped ZnO Nanorods Ultraviolet Photodetectors on Flexible Substrate
Authors: Young Sheng-Joue , Liu Y. H. , Khosla Ajit
Published: February 2020

In this study, high-density single crystalline Ga doped ZnO (GZO) nanorods were grown on flexible substrate by the hydrothermal method. From the FESEM image, it was found that GZO nanorods have a hexagonal wurtzite structure and the average length and diameter of the GZO nanorods were 1.35 μm and 31 nm, respectively. It was also found that high density vertically oriented nanorods are grown on the seed layer/flexible substrate. Further, Ga-doped ZnO nanorods metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors (PD) were fabricated. Under 1 V applied bias, the dark current and photocurrent of GZO MSM PDs were 8.60 × 10-9 A and 3.92 × 10-6 A, respectively. The responsivity of the synthesized GZO PDs were around 0.031 A/W with a sharp cutoff wavelength at 370 nm. The UV-to-visible rejection ratio of the GZO PDs sample was 23.87 as the measured responsivity at UV and visible peaks were 370 and 450 nm, respectively.
Novel Organic Electrode Materialsfor Innovative Thick Electrode Based Aqueous Batteries
Authors: Perticarari Sofia , Grange Elodie , Pellegrin Yann , Guyomard Dominique , Odobel Fabrice , Poizot Philippe , Gaubicher J
Published: February 2020

Thanks to the use of abundant chemical elements, organic chemistry provides great opportunities for discovering innovative electrode materials, which could be prepared (i) from renewable resources (biomass) and (ii) via eco-efficient processes, making the concept of greener and sustainable batteries possible [1]. Two types of reaction mechanisms can be used: n-type involving charge transfer with cation release/uptake and p-type involving anion uptake/release [2-5].

We are putting a lot of efforts on greener and sustainable organic batteries. In this communication, we report on novel materials, their uncommon reaction mechanism, and the performance of full aqueous cells.

We focus on aqueous organic batteries as a new promising green technology, barely studied yet, for which negative electrodes are missing. We have designed and synthesized novel mixed p- and n-type “bi-block” oligomer negative electrodes with repeating units made of naphthalene diimide and bipyridinium units [6]. They demonstrate optimal potential, extremely fast kinetics and highly competitive capacity and cyclability in both neutral aqueous Na and Mg electrolytes, including ocean water. Based on these findings, full organic cells bearing millimeter thick electrodes were assembled and tested [7]. These findings make a big step forward the design of low-cost rocking-chair dual-ion aqueous batteries.

References

1) P. Poizot, F. Dolhem, Energy Environ. Sci. 4, 2003 (2011).

2) Z. Song and H. Zhou, Energy Environ. Sci. 6, 2280 (2013).

3) S. Gottis, A.-L. Barrès, F. Dolhem, P. Poizot, ACS Appl Mater Interfaces 6, 10870 (2014).

4) E. Deunf, P. Moreau, E. Quarez, D. Guyomard, F. Dolhem, P. Poizot, J. Mater. Chem. A, 4, 6131 (2016).

5) E. Deunf, P. Jimenez, D. Guyomard, F. Dolhem, P. Poizot, Electrochem. Comm., 72, 64 (2016).

6) S. Perticarari, Y. Sayed-Ahmad-Baraza, C. Ewels, P. Moreau, D. Guyomard, P. Poizot, F. Odobel, J. Gaubicher, Adv. Energy Mater., 8, 1701988 (2018).

7) S. Perticarari, E. Grange, T. Doizy, Y. Pellegrin, E. Quarez, K. Oyaizu, A. J. Fernandez, D. Guyomard, P. Poizot, F. Odobel and J. Gaubicher, Chem. Mat., in revision
A First-Principle Study Towards Understanding Surface Reactions in Li-I2 Batteries
Authors: Liu Zhixiao
Published: February 2020

Large-scale stationary energy storage urgently demands to develop rechargeable batteries with low cost, high energy density, and enhanced cycling stability. Beyond conventional Li-ion batteries, secondary Li-I2 batteries based on the conversion reaction mechanism is considered as a promising next-generation energy storage device. However, Li-I2 batteries also suffer shuttle effect caused by the high solubility of iodine in the organic electrolyte.

A first-principles approach is employed to probe the effect of I2 molecules on corroding the metallic Li anode surface. It is found that the I2 molecule always tends to dissociate to two I atoms on the Li surface. Electrons in the metallic substrate spontaneously migrate to I atoms, resulting in the self-discharge. According to the ab-initio molecular dynamics simulation, the metallic Li surface can be oxidized to LiI species. LiI species cannot binding to the metallic substrate strongly and will be exfoliated easily, leading to the loss of active materials and irreversible capacity fade. According to the present simulation, LiNO3 additive can also prevent the Li surface from the iodization corrosion. The NO3
- group can completely dissociate and penetrate into the Li substrate, result in forming a protective ternary compound layer. This layer can provide a strong affinity to LiI species, leading to alleviating the loss of active materials. Beyond LiNO3 additive, using N-doped graphene is another strategy to improve the battery performance. The N dopant can provide a strong attraction to trap I2 molecules. In addition, the N heteroatom can shift the Fermi energy level above the pi-antibonding states, which can enhance the reduction and dissociation of the I2 molecule.
(Invited) Novel Design & Synthesis of Carbon for Lithium-Ion Batteries and Beyond
Authors: Paranthaman Mariappan Parans
Published: February 2020

The main goal of this research is to produce key fundamental understanding of how the bonding in carbon electrodes can be used to tailor ion transport, and how this correlates to the formation of SEIs that define the energy storage limits for next-generation batteries. We will address by tailoring electrode chemistry to control ion transport in the bulk and across the electrode-electrolyte interface. Theoretical calculations suggest that the interlayer distance of graphite as anodes is too small to accommodate the large Na+ ion, and an interlayer distance of > 0.37 nm is believed to be good for Na+ insertion. Detailed understanding of the morphologically tailored pyrolysis-recovered carbon is required to improve properties. The tailored morphology of the tire-derived carbon using a sulfonation process followed by pyrolysis yielded a high-quality carbon and the applicability of these hard carbons was demonstrated in several energy storage systems including lithium-ion batteries, sodium-ion batteries, and potassium-ion batteries. We will report on our recent neutron studies on the surface chemistry of the carbon material, vibrational spectroscopy of the molecular structure, chemical bonding such as C-H bonding, and intermolecular interactions of the carbon materials. In addition, we will also report our recent success with tire-derived carbon with either tin oxide or antimony/antimony oxide based composites as a low-cost, environmentally benign, and high capacity anode material for energy storage applications.

Acknowledgements

This work was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division.