bluuebunny/crossref_metadata_2025 huggingface dataset:
(Keynote) Dimensional Change of Oriented Polymers upon Heating
Authors: Kikutani Takeshi
Published: February 2020

Molecular orientation can be incorporated to the polymeric materials through either stretching in a solid state or elongation in a molten state. When a polymer has molecular orientation in a glassy state, shrinkage may proceed when temperature is increased above its glass transition temperature. Degree of shrinkage may vary depending on the temperature reached and the degree of molecular orientation.

In the case of crystalline polymers, however, shrinkage may be suppressed because of the occurrence of crystallization prior to the shrinkage. It should be noted that the crystallization rate can be accelerated significantly with the increase of molecular orientation. Accordingly, there can be a critical degree of molecular orientation; below which orientation relaxation proceeds upon heating, whereas above which spontaneous orientation enhancement caused by crystallization proceeds upon heating. In some cases, even the spontaneous elongation of materials takes place along with the progress of crystallization.

On the other hand, it is well known that the dynamics of polymeric materials is characterized by the wide range of relaxation time. This means that the state of molecular orientation can be manipulated through the combination of deformation/flow history and temperature history. Dimensional change of oriented polymeric materials upon heating is mainly governed by the oriented structure of relatively long relaxation time such as network structure of molecular entanglement. Based on this concept, we could prepare fibers which showed no birefringence but exhibited significant shrinkage with the increase of temperature. This is possible because birefringence merely reflects the degree of orientation of relatively short segments, i.e. short relaxation time, in the polymer chain.

Concept of manipulating the oriented structure of wide range of relaxation period leads to the idea of controlling the state of molecular entanglement. Based on this concept, we speculated that the polymeric materials of high strength and high toughness can be prepared if the material has rather homogeneous state of molecular entanglement, i.e. narrow distribution of molecular weight between adjacent entanglement points.

As-spun poly(ethylene terephthalate) (PET) fibers with rather homogeneous state of molecular entanglement was prepared through the control of melt spinning process. Applying the drawing and annealing processes to such as-spun fibers, high-strength PET fibers were prepared. To verify the applicability of the concept of homogeneous state of molecular entanglement, PET fibers prepared under various processing conditions were analyzed using the laser Raman spectroscopy. It was found that the narrow distribution of internal stress field and limited widening of such distribution upon applying the tensile stress to the fibers are the key factors for realizing the high-strength and high-toughness.
Modeling Viscoelasticity By Mesoscopic Coarse-Grained Models with Transient Bonds
Authors: Uneyama Takashi , Masubuchi Yuichi
Published: February 2020

Modeling of rheological behavior of polymeric materials is important when we perform simulations for material processing. Even if we limit ourselves to viscoelastic behavior, how to model and implement rather complex viscoelasticity is not clear. Various mesoscale coarse-grained models, such as the tube and slip-link models for entangled polymers, have been proposed and utilized. Recently, we have proposed a mesoscopic model for entangled polymers with dynamically reconstructable springs (so-called the multi-chain slip-spring model), in which multiple Rouse polymer chains are connected by transient slip-springs. The multi-chain slip-spring model is based on a well-defined effective free energy and the detailed-balanced dynamics, and it was shown that it can reproduce characteristic dynamical and rheological properties of entangled polymers well. The success of the multi-chain slip-spring model implies that the concept of transient bonds like slip-springs would be useful to model viscoelastic behavior of soft matters. In this work, we theoretically consider the modeling of viscoelasticity by utilizing the transient bonds and effective free energy. As a demonstration, we show simulations for particle systems with transient bonds, in which nontrivail dynamical and rheological properties are observed.
Multi-Scale Simulation of Well-Entangled Polymer Melt Flows in a Channel
Authors: Taniguchi Takashi , Sato Takeshi , Harada Kohei
Published: February 2020

In order to produce better polymeric goods, it is important to predict and to control a flow behavior of a polymeric fluid. To understand a flow behavior of a polymeric fluid, computational approach is quite effective. It is well-known that polymeric fluids exhibit complex flow behaviors owing to a strong correlation between the state of macroscopic flow and the microscopic state of polymer chains. The complex flow behaviors are originated from the stress tensor in the Cauchy momentum equation. When solving the equation, a constitutive equation is usually used to evaluate the stress tensor from the local deformation rate tensor and a set of parameters. By using a constitutive equation, however, it is difficult to reflect the microscopic state to the macroscopic flow. As one of the methods to overcome the difficulty, it has been proposed to use a multi-scale simulation (MSS) method where local microscopic states and the macroscopic flow are directly connecting each other.

So far, the MSS method has succeeded in predicting the flow in simpler geometries such as a flow in between two parallel plates and polymer melt flows passing a circular object in a two-dimensional periodic system. To develop further the MSS method that can deal with more industrially oriented problems, it is necessarily to investigate the applicability of the method to a flow in complicated geometry of boundary. In this context, we have applied the multiscale simulation technique to flows of polymer melts in a channel with 4:1:4 contraction and expansion geometry.

In the MSS method, we introduced Lagrangian particles which contain many chains to precisely maintain the microscopic states. As the microscopic polymer model, a slip-link model is used. Using the multiscale simulation method, we investigated the macroscopic spatial distribution of microscopic quantities, such as the spatial distribution of polymer chain orientation and the number of entanglements. We found that the number of entanglements strongly decreases around the middle of the polymer chains. This kind of information can be helpful when designing polymer melts with specific properties.
Fracture Behavior and Mechanical Properties of Rivet Joint By Using Ultrasonic Vibration with c-Frtp
Authors: Ohtani Akio
Published: February 2020

Fiber Reinforced Plastics (FRP) have been expected to be used for structural materials in various field because of its high specific stiffness and strength. In the case of using FRP for automotive structures, easy and reliable jointing process in a short time must be needed. Most easy jointing processes are adhesive joint with bonding agent or welding joint in the case of FRTP. However mechanical properties of these joint system depend on the interfacial properties between resin and fiber or resin itself, which are relatively poor. In the case of mechanical joint by using bolt and nut, or rivet system with metal materials, whole structure will be heavy. Therefore if FRP parts could be used as a jointing parts instead of rivets, the problems such as a increase of weight and process time of jointing should be overcome.

In this study, rivet joint with pultruded c-FRTP (continuous Fiber Reinforced Thermoplastic composite) rods with CF/PA commingled yarns covered with braided GF / PA commingled yarns and were performed by using ultrasonic welding machine with a die forming rivets for a pair of c-FRTP (CF/PA) plates with a joint structure. Mechanical properties of rivet joint were investigated by performing single lap joint test, and fracture behavior was also investigated by stopping the test in each region of the obtained diagram and embedding the sample for cross-sectional observation.
Large Scale Coarse-Grained Molecular Dynamics Simulations of Void Formations in Rubbers for Tires
Authors: Oikawa Masataka , Masubuchi Yuichi
Published: February 2020

Because wear-resistant is one of the demanded properties of tires used for motor cars due to the growing demand for resource saving, industrial developments toward such a direction have been attempted. However, attrition of rubber has not been fully elucidated yet. In this study, we have performed large scale coarse-grained molecular dynamics simulations of rubber to analyze the fracture that occurs inside the rubber from molecular level. In our model, the polymer molecules were represented by the coarse-grained beads-spring model. The filler particles were represented as clusters of beads, and their dispersion was reconstructed from the three-dimensional transmission electron microscope images of actual rubber. We added the coupling agent between polymers and particles to see the effect of interface modification. To reasonably accommodate the particle dispersion, we construct the large simulation box containing more than 130 million beads. After the sufficient equilibration, instantaneous stretch toward one direction was applied, whereas the box dimension for the other directions was fixed. During the relaxation process, dynamics of void formation was observed. As a result, we have found that a specific coupling agent can suppress the void formation at the interface. Owing to the result, we have developed the new tire product with high wear-resistance.
Evaluation of Anti-wear Properties and Internal Morphology of Graphite filled UHMWPE Composites Obtained by Octa Screw Extruder Process
Authors: Liu Cheng-Ying , Ishigami Akira , Kurose Takashi , Ito Hiroshi
Published: February 2020

Ultra-high molecular weight polyethylene (UHMWPE) has been regarded as a representative of bio-materials, especially for artificial prostheses for long term knee/hip joint use. In this work, we have produced micro-nano-composites by using graphite (Gr) as filler to increase the mechanical anti-wear property. The dispersion of graphite in the composites matrix and the influence of processing conditions was investigated by octa-screw kneading machine. The experimental results suggested that the elastic modulus of the composites raised by 37-70% with the addition of 2wt% Gr. The bending strength of the graphite filled micro-nano-composites also increased by 21-33%. In addition, the size of Gr on mechanical properties of the composites was affected. In the case of the average 20µm diameter Gr, the elastic modulus of the composites improved by 25% when compared to that of 5µm. In this presentation, we will discuss viscoelasticity and friction properties of Gr filled composites with different Gr size and shape
Thermal Energy Storage P(BeA-co-MMA) Microcapsules with Excellent Thermal Stability
Authors: Mao Yuchun , Gong Jin , Zhu Meifang , Ito Hiroshi
Published: February 2020

Latent heat storage systems are a highly efficient and environmentally friendly way to use residual heat and store renewable energy. Phase change materials, which can absorb or release the enthalpy of phase changes in certain temperature ranges, are considered one of the most reliable latent heat storage and thermoregulation materials. Phase change materials have been successfully used in the fields of solar energy, aerospace and aviation, environmental control and textiles. Among phase change materials, paraffin and n-alkane are the most popular due to their characteristics of high phase change enthalpy, high energy storage density, relative low volume change ratio, good physical and chemical stability, and no super-cooling or phase segregation behavior. More importantly, there are wide selective working temperature ranges which greatly extend their operating conditions.

Microcapsules are considered micro scale containers to prevent core from leaking, isolate from the surroundings and maintain chemical and functional stability in service. There are several methods to synthesize microcapsules: spray dying, complex coacervation, sol-gel, in-situ polymerization, suspension polymerization and emulsion polymerization. Among these, suspension polymerization has the advantages of being simple, cheap, stable, eco-friendly and being easily controlled, which makes it the most popular chemical method to synthesize microcapsules. The majority shell materials of traditional microcapsules are synthetic macromolecules. The properties of shell materials impact the application and processing conditions of the final energy storage composite materials greatly. Nevertheless, the low thermal stability and physical strength of polymers in nature strongly restrict application fields of microcapsules. What’s more, the evaporation or sublimation of core materials causes the low thermal stability.

In order to overcome these shortages of shell fracture, core leakage, core evaporation or sublimation existing in traditional microcapsules, we design a copolymer microcapsule with strong interaction force between shell and core parts, which has an unseparated surface layer between shell and core. The strong interaction force between shell and core allows the extreme improvement of thermal stability of microcapsules. The copolymer microcapsule is synthesized by suspension polymerization of behenyl acrylate (BeA) and methyl methacrylate (MMA). In this paper, we report the synthesis, size control and structure analysis of P(BeA-co-MMA) microcapsules which have both excellent thermal stability and high thermal energy storage capacity.
Sustained Lasing Using Colloidal Quantum Dots
Authors: Adachi Michael M
Published: February 2020

Colloidal Quantum dots (CQDs) are solution synthesized nanocrystals that exhibit bright emission and narrow bandwidth, making them promising for light emission applications such as down-conversion luminescence, light amplification, and lasing. The emission wavelength of CQDs can also be controlled by the size of the nanocrystals potentially leading to tunable color light emission. In this work, CdSe-CdS-ZnS core-shell-shell quantum dots were synthesized and incorporated into a distributed feedback optical cavity to demonstrate sustained lasing. We show that the duration of lasing is limited by thermal runaway and that thermal management in the form of engineering the CQDs to form ultra-compact films and using a thermally conductive substrate can lead to efficient heat dissipation and therefore sustained lasing. The ultra-compact films were achieved by replacing long-chained organic ligands with inorganic-halide passivation. The new CQD films exhibited high modal gain (1,200 cm-1) and a low amplified spontaneous emission threshold of 50kw/cm2 (average peak power). Sustained lasing was first demonstrated for a microsecond, followed by fully continuous wave operation.
(Keynote) The Versatility of Mesoscopic Solar Cells
Authors: Hagfeldt Anders
Published: February 2020

In our work on solid-state dye-sensitized solar cells (ssDSSC) we have recently shown that copper phenanthroline complexes can act as an efficient hole transporting material. We prepared ssDSCs with a novel organic dye WS-72 and [Cu(tmby)2]2+/+as redox system and achieved record power conversion efficiencies for ssDSCs of 11.7% [1]. With this redox system DSSCs give also excellent performance under ambient light conditions [2]. Our best DSC efficiency of 13.1% for a liquid Cu-complex electrolyte is achieved by the discovery that the PEDOT based counter electrode can be directly contacted with the dye/TiO2photoelectrode [3]. Thus, there is no space between the two electrodes minimizing diffusion limitations and fill factors up to 0.8 is achieved.

In our work on perovskite solar cells (PSC) we have achieved efficiencies above 20% with a mixed composition of iodide/bromide and methyl ammonium/formamidinium [4]. With the use of SnO2 compact underlayers as electron acceptor contacts we have constructed planar perovskite solar cells with a hysteresis free efficiency above 20% [5,6]. The strategy of cation mixing of the perovskite film was taken further by including the Cs in a so-called ‘triple cation’ composition, i.e. Cs/FA/Ma as well as Rb in a quadruple cation mixture [7,8]. Larger grains grown in a monolithic manner are observed and reproducibility and device stability are improved. For example, above 22% efficiency has been obtained with an outstanding open-circuit voltage of 1.24 V at a band gap of 1.63 eV entailing one of the smallest loss-in-potential of 0.39 V measured for any solar cell material. With regards to lifetime testing, we have shown a promising stability at 85 oC for 500 h under full solar illumination and maximum power point tracking (95% of the initial performance was retained). Recently, we have also commented on the standardization of PSC aging tests [9].

References

[1] Zhang et al. et al., Energy & Envir. Sci.,DOI: 10.1039/c8ee00661j

[2] Freitag et al. Nature Photonics, 11 (2017) 372

[3] Cao et al., Joule, https://doi.org/10.1016/j.joule.2018.03.017

[4] Bi et al., Science Advance, DOI: 10.1126/sciadv.1501170

[5] Correa et al., Energy & Envir. Sci., DOI:10.1039/C5EE02608C

[6] Anaraki et al., ACS Energy Lett. 2018, 3, 773−778

[7] M. Saliba et al., Energy & Envir. Sci., 2016, DOI: 10.1039/C5EE03874J

[8] M. Saliba et al., Science10.1126/science.aah5557 (2016)

[9] Domanski et al. Nature Energy 01 January 2018. DOI: 10.1038/s41560-017-0060-5
Chlorophyll-Based Organic–Inorganic Heterojunction Solar Cells
Authors: Wang Xiao-Feng
Published: February 2020

The intriguing properties of extremely efficient delocalization and migration of excitons in chlorophyll (Chl) J-type aggregates have inspired intense research activities toward their structural understanding, functional interpretation and mimicry synthesis. Herein, we demonstrated the J-aggregates of zinc methyl 3-devinyl-3-hydroxymethyl-pyropheophorbide a generated by spin-coating method for the application as donor material in titania-based organic-inorganic heterojunction solar cells with methyl trans-32-carboxypyropheophorbide a as the acceptor. We investigated the processing sovents, the dopants, the co-sensitizers as the key factors to determine the performance. We further studied the charge separation mechanism of such novel solar cells by the use of transient-absorption spectroscopy.
(Invited) Photocarrier Generation in Single-Absorber Organic Solar Cells
Authors: Nakayama Kenichi
Published: February 2020

Power Conversion efficiency of organic photovoltaic devices has exceeded 10% by taking advantage of bulk heterojunction (BHJ) structure, where donor and acceptor molecules are microscopically mixed. A remained problem is photovoltage loss from absorbed photon energy. In the BHJ system, LUMO offset is required to promote photodissociation at the donor-acceptor interface, causing serious photovoltage loss. To solve this problem, we are approaching it from single absorber cells, where there is no donor-acceptor interface. Generally, photogeneration efficiency in organic film bulk is quite low because of large exciton binding energy of Frenkel exciton. On the other hand, photogeneration from CT excitons occurs almost spontaneously in the BHJ system. If we could generate charge-transfer (CT) excitons in the single-component film directly, photovoltage loss would be reduced. Recently, we found intramolecular charge-transfer molecules including donor and acceptor units within one molecule show considerable high performance in the single-absorber device. In particular, DTDCPB having triphenyl amine unit (donor) and benzothiadiazole unit (acceptor) was a promising material for the single-absorber system. In this presentation, photogeneration process in the single-component film of CT molecules was investigated from several viewpoints. Molecular design for intramolecular charge-transfer absorption is discussed from the viewpoint of quantum chemical calculation and organic synthesis. The photocarrier dynamics in the single-absorber solar cells is investigated by several techniques such as intensity-modulated photovoltage/photocurrent (IMVS/IMPS) and time delayed collection field (TDCF). Exciton binding energy, that is a key factor for photodissociation in the film bulk, was estimated by Onsager-Braun analysis by using a planar device.

Figure 1
(Invited) Micro- and Nano-Structure p-n Junction Based Organophotochatalyst Film
Authors: Nagai Keiji , Ahmad Mohd Fairus , Abe Toshiyuki
Published: February 2020

The present paper describes organic semiconductor based photocatalyst with p-n junction. A typical material combination is phthalocyanine (H2Pc) and 3,4,9,10-perylenetetracarboxylic-bis-benzimidazole (PTCBI) without transition metal element. It responds full spectrum of visible light and reaching to near infrared region. The film type photocatalyst was prepared by vapor deposition technique with the thickness around 10 to 100 nm, which is relating to absorbance. Typical applicable reactions are downhill redox reaction such as mineralization of volatile organic molecules. The engineering quantum efficiency per incident photon number is high >10 %. When the combination is modified with noble metal nanoparticles or transition metal ion into phthalocyanine, water reduction and oxidation occurred in the presence of bias potential under visible light illumination. Due to the film structure, layering of the film is possible for a practical application, and it is useful to utilise natural sunlight. Under the weak light illumination, internal quantum efficiency becomes high which is merit for the layering use.

By changing microstructure and nanostucture of p-n junction, interesting enhancements were observed, such as near infrared region response maybe due to charge transfer complex formation between H2Pc and PTCBI. A terrace bilayer (TB) of p-n junction exhibited potential structure at the interface and it was observed by the use of scanning Kelvin probe microscopy (SKPM).

1) K. Nagai et al. ChemSusChem,
4 (6), 727-730, (2011).

2) K. Nagai et al. ACS Sustainable Chem. Eng., 1, (8), 1033-1039, (2013).

3) M.-F. Ahmad et al. Electrochemistry
., 86, in press, (2018).
(Invited) Microstructure and Capacity Design of Si-Silicide Alloys As a High-Performance Anode for Li Secondary Batteries
Authors: Umirov Nurzhan , Kim Hyang-Yeon , Kim Sung-Soo
Published: February 2020

Si and Si-based alloys considered as the most desired anode material for LIB owing to high gravimetric and volumetric capacity (3579 mAh g-1and 2200 mAh cm-3, corresponding to L15Si4 state). Despite academic and industrial efforts, applied on resolving the poor cycle life caused by the large volume changes upon redox reactions with Li+, the commercial use of silicon as an anode has not yet been implemented.

Here, we report a comprehensive study of Si-based binary, ternary and multi alloys prepared by a facile and inexpensive process, melt-spinning. This approach allows to synthesize a proper microstructure by control a certain level of solidification speed (around 103–106 K/s) and known as the most suitable method for the mass production of alloys. In particular, through the control a size of active Si grains, which are well dispersed in the inactive matrix, we have examined electrochemical properties of Si-Ni binary alloys with the different atomic ratio. The gradual change of delithiation curve at 0.3V was observed upon cycling. OCV studies reveal the change of material state and compliment the observation of Chevrier et.al [1]. In our recent studies, we have designed Si–Fe–Al ternary alloys and practically examined the reliability of the proposed capacity prediction approach based on the Lever rule and phase diagram. Accordingly, half-cell electrochemical test results, XRD and TEM investigations revealed fairly good agreement of the calculated and realized capacities of the Si–Fe–Al alloys. Another attempt was applied to design an alloy with nanostructured crystalline Si (active) surrounded by amorphous matrix (inactive). XRD, HR-TEM and DSC results supported the evidence of formation as the designed microstructure. Effect of the amorphous matrix on the electrochemical performance of the Si-alloy as an anode was investigated and will be discussed at the conference.

Reference:

[1] Chevrier, V. L., Liu, L., Le, D. B., Lund, J., Molla, B., Reimer, K., & Eberman, K. W. (2014). Evaluating Si-based materials for Li-ion batteries in commercially relevant negative electrodes. Journal of The Electrochemical Society, 161(5), A783-A791.
Synthesis of Fluorine-Free Polymer Electrolyte Having Lithium Bissulfonimide Unit
Authors: Matsumura Yoshimasa , Shiraiwa Toshiki , Hayasaka Tsuyoshi , Yoshida Saki , Ochiai Bungo
Published: February 2020

Polymer electrolytes are important materials of Li ion batteries enabling leakage resistance, miniaturization, and thinning. However, the ion conductivities of polymer electrolytes lower than general electrolyte solutions of Li ion battery, limit the performance of cells. To develop novel polymer electrolytes with good ionic conductivity, we focused on the structure of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). LiTFSI is a widely used Li electrolyte salt having high ion conductivity, and its organic structure can be chemically modified. Hence, some polymer electrolytes bearing similar structures were synthesized. However, their ion conductivity are in an insufficient range of 10-5S/cm probably due to their very high Li ion concentrations and high glass-transition temperature (T
g). Herein, we describe the synthesis of a novel polymer electrolytes exhibiting high ion conductivity by copolymerization of lithium N-methanesulfonylvinylsulfoneimide (LiMSVSI) for the electrolyte component with poly(ethylene glycol) methyl ether acrylate (PEGMA) for low T
gand ion conductive pathway (Scheme 1).

The copolymerization of LiMSVSI with PEGMA was carried out by a two-stage heating method. The first stage in ethanol at 60 ºC gave a mixture of the copolymer and the residual monomers. The second stage at 100 ºC after evaporating solvent converted the monomers in quantitatively. The T
gof the copolymer was determined as –62 ºC by differential scanning calorimetry (DSC) analysis. The copolymer exhibited good ionic conductivity in the range of 10-4–10-5 S/cm due to its labile ionic structure and low T
g. In this paper, we will also describe the copolymerization behavior of LiMSVSI with other comonomers.

Figure 1
Catalytic Motifs in Bio-Inspired Materials As New Generation Electrocatalysts
Authors: Coskun Halime , Aljabour Abdalaziz , Stadler Philipp , Sariciftci Niyazi Serdar
Published: February 2020

Bio-inspired and bioorganic materials gain outmost of interest due to a wide application area. In the past years, hydrogen-bonded organic semiconductors relying on indigoid pigment family are applied in various device geometries e.g. organic solar cells, organic field effect transistors but also as thin film electrodes in catalysis [1,2]. Currently, the integration of the bio-inspired materials in sustainable catalysis is powerful. Especially, organic functionalities present in the chemical structure of this new material class provide these compounds outstanding properties in terms of using these functional themes as catalytic active centers to substitute state-of-the-art metallic catalysts. Herein, we report on the suitability of a bio-originated polymer – Polydopamine (PDA) - as an effective electrocatalyst [3]. Polydopamine is a major pigment of the eumelanin family. Due to its hydrogen-bonded sequences in the conjugated structure, stabilized over hydroxyl, amine and carbonyl groups, PDA is a prominent competitor for the new generation of sustainable catalysis. We engineered a new synthetic pathway for the polydopamine electrode prepraration [4]. We apply the chemical vapor deposition technique in the presence of the monomer dopaminhydrochlorid together with sulfuric acid as an oxidant in order to form polydopamine films directly on 3D, sponge-like carbon felt electrodes, creating an increased catalytically active surface area. Electrochemical investigations exhibit the interaction and interplay of the functionalities in catalytic processes resulting in high yields and current densities and thus reducing energy losses.

[1] Glowacki E. D.; Irimia-Vladu M.; Kaltenbrunner M.; Gasiorowski J.; White M. S.; Monkowius U.; G. Romanazzi G.; Suranna G. P.; Mastrorilli P.; Sekitani T.; Bauer S.; Someya T.; Torsi L.; Sariciftci N. S.; Adv. Mater.,
2013, 25, 1563–1569.

[2] Glowacki E. D.; Romanazzi G.; Yumusak C.; Coskun, H.; Monkowius U.; Voss G.; Burian M.; Lechner R. T.; Demitri N.; Redhammer G. J.; Sünger N.; Suranna G. P.; Sariciftci N. S.; Adv. Funct. Mater.; 2014, DOI: 10.1002/adfm.201402539.

[3] Coskun, H.; Aljabour, A.; De Luna, P.; Farka, D.; Greunz, T.; Stifter, D.; Kus, M.; Zheng, X.; Liu, M.; Hassel, A. W.; Schöfberger, W.; Sargent, E. H.; Sariciftci, N. S.; Stadler, P.; Sci. Adv.
2017, 3 (8), e1700686 DOI: 10.1126/sciadv.1700686.

[4] Coskun, H.; Aljabour, A.; Uiberlacker, L.; Strobel, M.; Hild, S.; Cobet, C.; Farka, D.; Stadler, P.; Sariciftci, N. S.; 2018, 645 (August 2017), 320–325 DOI: 10.1016/j.tsf.2017.10.063.
Study of Sensing Behavior of Conductive Hydrogels
Authors: Ahmed Kumkum , Shiblee MD Nahin Islam , Kabir M. Hasnat , Khosla Ajit , Furukawa Hidemitsu
Published: February 2020

Hydrogels having shape memory behavior are one of the smart materials with numerous possible application in sensor, optical and biomedical field. Thermo-responsive gels have the ability to show reversible shape transformation due to the melting induced order-disordered transitions of the molecular constituent. Our group has developed poly(dimethyl acrylamide-co-stearyl acrylate (DMAAm-co-SA) based shape memory gels (SMG) [1] with high mechanical strength, very good transparency and biocompatibility having potential application in different sectors [2]. Introduction of conductive properties in hydrogels can create high potential in the field of medical treatment (drug release), electrochemistry (bioactive electrode coating), sensors and actuators. In this work we have focused to combine the tunable physical and mechanical properties of the SMGs with the electrical activity of an electroactive component in order to bring out new prospects in material engineering. However, conductivity is not part of the inherent characteristics of the hydrogels, it can be provided by other materials or particles that are incorporated within the network of the hydrogels (e.g., conductive particles, conjugated polymers, etc.). Fully swollen hydrogels with conducting particles, such as graphite, carbon nanotubes or metallic particles incorporated in their structure typically show conductivity but conductivity is inversely affected by the swelling ratio, and the hydrogels exhibit brittle mechanical behavior [3]. In this work conductivity of the SMGs has been achieved by chemically polymerizing EDOT (with PSS as the molecular dopant) within the network of fully swollen SMG. A wide variety of conductive SMG with tunable mechanical elasticity, softness and swelling degree has been developed by varying crystalline monomer (SA) ratio and comparative study with pristine SMG revealed that conductive network did not affected their swelling degree and mechanical properties extremely. Conductive SMGs with low SA content has been found to be highly conductive with high swelling degree compared to the SMG with high SA content. We studied their electric resistance as a function of applied pressure or strain and developed an Arduino based systems for application in force sensing resistor devices.

References

[1] Kabir, M.H., Ahmed, K. Furukawa, H., Microelectron. Eng. 150, 43–46 (2016).

[2] Amano, Y; Hidema, R; Gong, J; Furukawa, H. Chem Lett.,41, 1029-1031 (2012)

[3] Morita, S; Kawai, T; Yoshino, K. J. Appl. Phys., 69 (8), 4445−4447 (1991).
Nanoceramic NiMn2O4 Powder-Based Resistance Thermometer for Soil Temperature Measurement Application
Authors: Kumar S K Naveen , Aniley Almaw Ayele , Kumar A Akshaya , Fernandez Renny Edwin , Bhansali Shekhar
Published: February 2020

The objective of this study is to construct a thermometer for soil temperature measurement application using sol-gel derived nanoceramic NiMn2O4 powder. The nanoceramic NiMn2O4 powder has been prepared using wet chemical method and characterized by FESEM/EDS and XRD. FESEM results confirmed its uniform morphology and the formation of the nanopowder. EDS confirmed that the powder consists of Ni, Mn, and O2. Based on the XRD analysis results and Scherrer’s formula the average crystallite size became 34nm. The powder then compressed in electrically insulator but thermally conductor tube manually to make the thermistor based thermometer. Two pieces of folded and rolled Aluminum foils as electrical contacts followed by two Aluminum lead wires were connected to the two opposite terminals of the tube. The thermometer is calibrated and characterized using LM35 IC temperature sensor integrated with Arduino Atmega328. The thermometer can measure a soil temperature up to 42℃. The embedded system for the thermometer is done using Arduino microcontroller and Arduino software with signal conditioning circuits. This is the first kind of thermometer which is based on nanomaterials for soil temperature measurement application in Agriculture.

Keywords:
NiMn2O4; nanoceramic powder; thermometer; thermistor; soil temperature; calibration

Figure 1
(Plenary) Recent Progress, Development, and Innovation of Photocatalysis
Authors: Fujishima Akira
Published: February 2020

Text to come.
(Invited) Mechanisms and Material Impacts of Overcharge in Lithium Ion Batteries
Authors: Torres-Castro Loraine , Lamb Joshua , Karulkar Mohan
Published: February 2020

Traditional monitoring of electrochemical cells and batteries has been limited to observation of voltage and temperature of the cell or cells. While this monitoring can be very robust, there are limits to how predictive voltage and temperature behavior can be prior to a thermal runaway event. Ultimately, voltage and temperature changes are often lagging symptoms of battery failure, and by the time a noticeable change is detected, it is too late to arrest cell failure with intervention or maintenance. Further, instantaneous voltage and temperature monitoring are often inadequate to determine the state of a battery at rest, particularly if the battery has been previously subjected to an abusive condition. Knowledge of the level of stability of a damaged battery would allow for both safer and more efficient handling of the abused battery.

This work examines the application of Electrochemical Impedance Spectroscopy (EIS) and Differential Capacity calculations (dQ/dV) as tools for determining the state of stability (SOS) of an electrochemical cell or battery. The cells used for this study were commercial 10 Ah NMC pouch cells and 10Ah LFP cells subjected to electrical and thermal abuse coupled with EIS monitoring. This aims to not only provide a deeper understanding of how abused cells and batteries fail but also form the technical basis of a tool that could ultimately be used to interrogate cells of unknown stability and even monitor active cells for early signs of damage or failure. Fast impedance monitoring hardware previously developed at Idaho National Laboratory is used to provide not only monitoring after an abusive battery test but also look for changes in the cell while abusive conditions are applied. Differential capacity calculations are explored both before tests and after moderate levels of abuse to explore any noticeable changes that may be monitored during charge and discharge operations. The electrochemical techniques are supported with materials evaluations to further understand the impact of abusive conditions on the constituent materials.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
Dual Electrolyte Aluminum-Air Flow Battery Using Methanol Anolyte
Authors: Teabnamang Pemika , Kheawhom Soorathep
Published: February 2020

Aluminum-air batteries have received considerable attention as a cost-effective energy storage system due to their high theoretical specific capacity of 2.98 Ah/g. However, corrosion of the aluminum anode in alkaline electrolyte limits their practical application. Herein, this issue was addressed by implementing dual electrolyte flow battery. The cell structure consists of aluminum anode | anolyte | anion exchange membrane | catholyte | air cathode.

The anolyte is 3M KOH in methanol containing different percentages of deionized water (0, 5, 10 and 20) wt. %. The catholyte is a gel polymer electrolyte based on Carbopol 940. The results showed that the increase of water content in the anolyte reduces the overpotential of the cell but increases hydrogen evolution (anode corrosion). At 10 mA/cm2 current density, the anolyte without water showed the highest specific capacity of 2,328 mAh/g, which is 78% aluminum utilization. The specific capacity significantly decreases as the water content in the anolyte increases due to the higer rate of the anode self-corrosion.
Freeze Tape Casting Derived Li7La3Zr2O12 Electrolyte Architecture with Oriented Ion Conduction Channels
Authors: Yi Eongyu , Shen Hao , Sofie Stephen , Chen Guoying , Doeff Marca
Published: February 2020

The high interfacial impedance of garnet electrolyte based solid state batteries has been addressed recently by constructing 3D interfaces in which a random network of solid electrolyte extends to the anode/cathode layer to serve as anolyte/catholyte. Thicker active material layers can be achieved with minimal performance loss compared to deposition derived approaches in such configurations as well. The cell architecture can be further improved by forming directional solid electrolyte channels with low pore tortuosity approaching unity compared to randomly oriented pores, thus imparting higher ion mobility along the transport direction during charge/discharge. Freeze casting, magnetic alignment, and laser ablation are some of the methods that have been used in forming aligned ion conduction channels in lithium ion battery applications and have shown performance improvement over the randomly oriented counterpart.

In order to build 3D interfaces with vertically aligned solid electrolyte channels at practical sample thicknesses with potential for scaling, we introduce freeze tape-casting, a combination of tape-casting and freeze casting, to continuously produce green tapes of Li7La3Zr2O12 with vertically aligned pore channels. LLZO was selected as it is one of the most promising solid electrolytes and is stable with Li metal anodes. On sintering, LLZO scaffolds in which LLZO sheets are vertically aligned are obtained. In parallel, processing optimization has been made on producing sintered thin films of LLZO by tape-casting and sintering. We show that porous/dense bi-layers and porous/dense/porous tri-layers of LLZO are produced readily by stacking and sintering the tape-cast and freeze tape-cast LLZO green tapes. Pores are filled with active material and current collector components to complete the cell, and the porous layers of various thicknesses can be mixed and matched as desired per loading requirements. The thicknesses of the porous and dense layers could be reduced down to 100 and 30 µm, respectively. This novel solid electrolyte framework shows great potential to advance the field of solid state battery research. Furthermore, the approach can readily expand to other Li or Na conducting oxide electrolytes to take advantage of the unique architecture.
Binder Free Synthesis of Sulphur Doped Co3V2O8 Nanoarray for Hybrid Asymmetric Supercapacitor Application in Aqueous and Non-Aqueous Medium
Authors: Sharma Gyan Prakash , Gupta Prashant Kumar , Pala Raj Ganesh , Sivakumar Sri
Published: February 2020

Metal vanadate are the class of compound for high performance electrochemical charge storage application due to its multiple stable oxidation states, high electrical and ionic conductivity and high rate capability. Among all the metal vanadate, Co3V2O8 is one of the potential candidate due to low cost and environmentally benign nature of cobalt. However, the introduction of Sulfur in Co3V2O8 matrix substantially improves the electrochemical performance by improving the electrical conductivity. Herein, we report Sulfur doped Co3V2O8 (S-Co3V2O8) nanosheet arrays grown on Ni foam hydrothermally without using any binder. As synthesized Co3V2O8 attains nanosheet morphology with height of ~200 nm and thickness of ~10 nm. We note that the shape and size of S-Co3V2O8 nanosheet arrays remain unchanged after the doping of sulfur in Co3V2O8. Further, the thickness of nanosheet increases with increasing reaction time. We observed that the electrochemical performance of S-Co3V2O8 nanosheet array is ~25% better than the undoped Co3V2O8 nanosheet arrays. In aqueous alkaline electrolyte, S-Co3V2O8 nanosheet array exhibits a specific capacity of 1476 C/g (3690 F/g) at 2 A/g with enhanced rate capability and an excellent capacity retention of 94.2% at 5 A/g specific current after 4000 cycles. The doping of sulfur improves the electrochemical performance due to its low electronegativity and large size as compared to oxygen, which creates a robust structure, better transport properties and improved charge storage capacity. An asymmetric supercapacitor fabricated using S-Co3V2O8 nanosheet arrays as cathode and activate carbon (AC) as anode shows high specific capacity (or capacitance) of 174.5 C/g (or 116.33 F/g), energy density (36.4 Wh/kg) and power density (740 W/kg) at 2 A/g with 98.4% capacity retention after cycles. Further, Li-ion hybrid capacitor fabricated in the CR2032 coin cell exhibits specific capacity of 994 mAh/g with energy density of 695 W/kg at specific current of 1 A/g with good rate capability and 46.5% capacity retention after 100 cycles renders it as a potential candidate for future high energy storage system with long term durability.
Modeling the Effects of Cycling on Dendrite Growth in Lithium Batteries
Authors: Tan Jinwang , Ryan Emily
Published: February 2020

Dendrite growth is an ongoing challenge in lithium batteries. Over multiple charge and discharge cycles dendritic growth leads to a decrease in battery performance and increased safety issues due to short circuiting. The morphology and growth rate of dendrites depend on a number of factors including the rate and depth of charge/discharge. In this work a computational model of dendrite growth at the interface is used to investigate the effects of cycling on dendrite growth rate and morphology. The model resolves the interfacial chemical-physical processes and simulates multiple charge and discharge cycles. Results show that dendrite growth depends on both the charging and discharging cycles, which can lead to heterogeneous growth patterns based on the levels of deposition and dissolution of lithium during the cycles.
Comsol Modelling of the Experimental Results Obtained from a Lithium Ion Battery with a Low Binder Content Lithium Iron Phosphate (LiFePO4) Cathode
Authors: Watson Venroy George , Kannan Dhevathi Rajan Rajagopalan , Morris Larry , Shellikeri Annadanesh , Moss Pedro L. , Weatherspoon Mark H. , Zheng Jim P. , Yeboah Yaw D. , Kalu Egwu Eric
Published: February 2020

Lithium iron phosphate has been a promising cathode for application in lithium ion batteries (LIBs) due to safety, flat discharge profile and high theoretical capacity of 170 mAh/g. Despite the positive attributes, lithium iron phosphate cathode fabrication methods requiring high binder content (for example, polyvinylidene fluoride), which is seen as dead weight and electrically neutral, affect the capacity performance and present a challenge in obtaining electrodes in an environmentally friendly manner.1-4 As a result, an effective experimental or modelling approach to maximize the performance of a LiFePO4 electrode is valuable to the energy storage field. Herein, use of 95% active material + 5% binder cathode was modeled in COMSOL based on the physical experimental set up. Interestingly, at 0.5 C rate, discharge capacities from COMSOL model and experimental results were 26 Ah/m2 and 23 Ah/m2, respectively. This indicates that use of COMSOL can help us to understand parameters to modify before a physical electrode fabrication is done experimentally. This study intends to investigate various C rates comparison between experimental results and COMSOL’s results, in order to identify the optimum operational conditions for LIBs using low binder content LiFePO4 cathode.

REFERENCES

C-C. Chang, L-J. Her, H-K. Su, S-H. Hsu, Y.T. Yen, Effects of Dispersant on the Conductive Carbon for LiFePO4 Cathode, Journal of the Electrochemical Society, 158 (5), (2011) A481-A486.

Shim, A. Sierra, K. Striebel, abstract #125, IMLB11, Monterey, USA, June, 2002.

Ravet, Y. Chouinard, J.F. Magnan, S. Besner, M. Gauthier, M. Armand, Electroactivity of natural and synthetic triphylite, J. Power Sources 97–98, (2001) 503–550.

A. Striebel, A. Guerfi, J. Sim, M. Armand, M. Gauthier, K. Zaghib, LiFePO4/gel/natural graphite cells for the BATT program, J. Power Sources 119–12, (2003) 951-954.

M. Mastali, M. Farkhondeh, S. Farhad, R. A. Fraser, M. Fowler, Journal of The Electrochemical Society, 163 (13) (2016) A2803-A2816.
(Invited) Prato Addition to C70: A New Adduct and Water-Soluble Derivatives
Authors: Liosi Korinne , Yamakoshi Yoko
Published: February 2020

Due to the higher absorption of light at longer wavelengths and increased lifetime of the triplet state, C70has been recognized as a better photosensitizer than C60for applications in photodynamic therapy (PDT). Similar to C60, the main obstacle to bioapplication of C70is its hydrophobicity, resulting in insolubility in water or water-miscible solvents and rendering functionalization with water-soluble anchors necessary. Additional complications in the functionalization of C70is lower symmetry of the molecule in comparison to C60. Even mono-addition reactions can provide several distinct derivatives of C70, which may exhibit a different range of the functions of the obtained derivatives.

In this study, we used a 1,3-dipolar cycloaddition reaction (Prato reaction) for the functionalization of C70. It is known that this reaction provides very stable pyrrolidine adducts of fullerenes in sufficient yields. We used a N-glycine derivative 1and formaldehyde in the Prato reaction; three obtained adducts (2A-C) were purified by HPLC (Figure) and their structures were elucidated by 1H and 13C NMR. While the addition sites of two major adducts 2Aand 2Bwere found to be ab-[6,6] and cc-[6,6] – similar to the previous reports – the structure of the third minor adduct 2Cwas determined as dd-[5,6]-2,in contrast to the previous studies. The deprotection of major adducts 2A-B under acidic conditions and subsequent conjugation with PEG-NH2derivatives successfully provided water-soluble C70-PEG conjugates.

Figure 1
(Invited) Self-Assemble of Supramolecular Polymers of Porphyrin-Bisfulleropyrazoline Tweezers
Authors: Caballero Ruben , Langa Fernando , de la Cruz Pilar
Published: February 2020

Along the last years, the utilization of non-covalent interactions for the construction of supramolecular polymers has evolved as one of the most attention-grabbing fields in chemistry leading to new materials with exciting properties. Considering the different types of motifs, p-p interactions have been scarcely studied.

Here, we will present the regioselective synthesis of a fulleropyrazoline-bisadduct by tethered directed synthesis from bisnitrile imines, opening of the tether and preparation of a tweezer bis-(Zn-Porphyrin)fullerene. Interestingly, the formation of oligomers by p-p fullerene-porphyrin interaction up to 13 units has been detected by MALDI-TOF mass spectrometry.

Figure 1