bluuebunny/crossref_metadata_2025_split huggingface dataset:
Defect Chemistry and Lithium Transport in ANTI-Perovksite Superionic Conductors
Authors: Ciucci Francesco , Lu Ziheng 
Published: February 2020

Solid state electrolyte with fast lithium conduction is the core of the all-solid-state Li battery technology. By substituting the organic electrolyte with a piece of non-flammable ceramic material, we can achieve a better safety, a higher specific capacity and a higher energy density. To date, the major bottle neck for this technology is the slow bulk diffusion of solid state electrolyte and the interfacial incompatibility between the electrolyte and electrodes. To resolve these issues, several families of fast ionic conductors have been developed. The understanding of Li diffusion in these materials is essential to the development of novel family fast ionic conductors. In this sense, atomistic modeling provides us with a unique tool to obtain comprehensive information on the atom motion which is so far hard to access with experimental techniques. In this work, we use density functional theory (DFT) calculations as well as large scale classical molecular dynamics (MD) simulations to simulate the Li diffusion in a novel family of superionic conductor, lithium-rich anti-perovskites and provide an understanding of the Li diffusion behavior.
Lithium-rich anti-perovskites (LiRAPs) are a promising family of solid electrolytes, which exhibit ionic conductivities above 10−3 S cm−1 at room temperature, among the highest reported values to date. We investigate the defect chemistry and the associated lithium transport in Li3OCl, a prototypical LiRAP, using DFT calculations and classical MD simulations. We studied three types of charge neutral defect pairs, namely the LiCl Schottky pair, the Li2O Schottky pair, and the Li interstitial with a substitutional defect of O on the Cl site. Among them the LiCl Schottky pair has the lowest binding energy and is the most energetically favorable for diffusion as computed by DFT. This is confirmed by classical MD simulations, where the computed Li ion diffusion coefficients for LiCl Schottky systems are significantly higher than those for the other two defects considered and the activation energy in LiCl deficient Li3OCl is comparable to experimental values. The high conductivities and low activation energies of LiCl Schottky systems are explained by the low energy pathways of Li between the Cl vacancies. We propose that Li vacancy hopping is the main diffusion mechanism in highly conductive Li3OCl.
High-Performance Solid-State Battery Enabled By a Stablized Plastic-Crystal Interlayer
Authors: Lu Ziheng , Ciucci Francesco 
Published: February 2020

Lithium-ion batteries (LIBs) are key devices for energy storage in modern day life. However, conventional LIBs suffer from several safety issues caused by the organic liquid electrolytes. Replacing the organic component with a piece of lithium-ion conductive ceramic, i.e., solid electrolyte, can in general solve the problem. Garnet-based oxide Li7La3Zr2O12(LLZO) is known to have good conductivity and stability when doped with proper dopants such as Ta, making it a promising solid electrolyte. However, due to the solid-solid contact problem with electrodes, the performance of solid-state batteries are not satisfactory.
We developed a modified plastic-crystal material based on succinonitrile that could be used as a deformable interlayer between electrodes and the solid electrolyte. The high lithium conductivity and the plasticity of the interlayer enables a good performance of the solid-state Li|LLZO|LiFePO4 battery even at room temperature. By adding a stabilizer to succinonitrile, we were able to use the interlayer at both LiFePO4|LLZO and Li|LLZO interface. The battery could be stably cycled at room temperature with a capacity of 140mAh/g.
(Invited) Advances in 2D Materials Production; From R&D to Commercialization
Authors: Wiper Paul , Gonçalves Gonçalo , Chen Bingan , Jouvray Alex , Teo Ken 
Published: February 2020

Over the past decade there has been considerable research focus on 2D materials. In particular, graphene, hexagonal boron nitride (hBN) and the family of transition metal dichalcogenides (TMDs), to name a few, exhibit unique electronic, optical and physical properties which can be exploited within various technologies and new application areas.
Besides the extraordinary advances in 2D materials research, their commercialization still remains challenging, especially for applications like electronic/optoelectronics, advanced coatings and energy-storage systems, where high quality, large scales, high throughput and reproducibility are required. From the available growth techniques, which play an important role on the materials properties, chemical vapour deposition (CVD) has proved to meet the aforementioned requirements.
In this presentation an overview of our technology capabilities and CVD graphene systems are reported with an emphasis on which market these tools can penetrate. We introduce our roll-to-roll system which can produce continuous monolayer or multilayer graphene coatings onto a variety of substrates. Finally, we introduce our systems for 2D growth highlighting the benefits and versatility of the systems.
(Invited) Precision Synthesis of Subnanoparticles Using a Dendrimer Reactor
Authors: Yamamoto Kimihisa 
Published: February 2020

Dendrimers are highly branched organic macromolecules with successive layers or “generations” of branch units surrounding a central core. Organic inorganic hybrid versions have also been produced, by trapping metal ions or metal clusters within the voids of the dendrimers. Their unusual, tree-like topology endows these nanometer-sized macromolecules with a gradient in branch density from the interior to the exterior, which can be exploited to direct the transfer of charge and energy from the dendrimer periphery to its core.
We show that tinchloride, SnCl2 and FeCl3 complexes to the imines groups of a spherical polyphenylazomethine dendrimer in a stepwise fashion according to an electron gradient, with complexation in a more peripheral generation proceeding only after complexation in generations closer to the core has been completed. By attaching an electron-withdrawing group to the dendrimer core, we are able to change the complexation pattern, so that the core imines are complexed last. By further extending this strategy, it should be possible to control the number and location of metal ions incorporated into dendrimer structures, which might and uses as tailored catalysts, building blocks, or fine-controlled clusters for advanced materials.　The metal-assembly in a discrete molecule can be converted to a size-regulated metal particle with a size smaller than 1 nm as a molecular reactor. Due to the well-defined number of metal particles in the subnanometer size region, its property is much different from that of bulk or general metal nanoparticles.
Anticorrosive Coating Based on Glycerol and Polyurethane Organic-Inorganic Hybrids
Authors: Braz Álvaro Guimarães , Pulcinelli Sandra Helena , Santilli Celso Valentim 
Published: February 2020

The corrosion of metallic materials is one of the most common natural problems encountered in the different fields of engineering. To delay the corrosion effects, some kinds of organic inorganic hybrid (OIH) coatings were tested as protective barrier. In this work we proposed the use of glycerol as a renewable source reagent for the development of a sol-gel green-coating based on polyurethane (PU) and siloxane (PU-Sil). The PU was synthesized from diisocyanate, MDI (4,4'-methylenebis (phenyl isocyanate)) and glycerol and the effect of the ratio of APTES ((3-aminopropyl) triethoxysilane) and MDI in the properties and structure of the PU-Sil material evaluated. The FTIR characterization showed that the OIH material has carbamate groups in the polymer chain that are related to PU formation and urea groups due to the formation of the link between free NCO groups and the siloxane. 13C and 29Si NMR/MAS spectra showed characteristic bands of the PU chain and siloxane polycondensation degree of about 80%, respectively. From the thermogravimetric analysis was possible to demonstrate the effect of APTES on the thermal stability of the material. The electrochemical impedance spectroscopy measurements performed on the PU-Sil coated carbon steel demonstrated the effect of the amount of siloxane in the corrosion protection performance in saline solution. Lifetimes longer than 125 days were verified from impedance over 106 Ohm.cm2 observed for PU-Sil coated carbon steel. The developed green sol-gel route allowed producing an OIH material of low cost, formed by cross-linked polymer chains with good performance for steel corrosion protection.
Keywords: green-coating, corrosion protection, polyurethane – siloxane.
Optical and Electrical Properties of ECR-PECVD Grown SiCN Thin Films
Authors: Abdelal Aysegul , Khatami Zahra , Mascher Peter 
Published: February 2020

Recent progress in scaling down the metal-oxide semiconductor (MOS) devices accompanied limitations arising from quantum effects, which leads to a search for new materials. Silicon oxide (SiO2) thin films have been a favourable dielectric for more than 4 decades. Their usage have become impractical due to the power dissipation and delay in interconnects. To increase the electrical performance, low extinction coefficient (low-k) dielectric materials are being developed as a substitute to SiO2. Those materials draw considerable attraction due to their advances in the integrated circuit technology to increase the transistor density. Among numerous materials, silicon carbonitride (SiCN), which is an intermediate compound between silicon nitride (SiN) and silicon carbide (SiC), has become noteworthy with its unique properties as low-k, robustness, high thermal stability, and wide bandgap of 2.2eV- 5eV1.
In this work we present the optical, structural, and electrical analysis of SiCN thin films grown using electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD). The influence of the precursors (SiH4, C2H2, and N2 gases) on the composition and electronic structure of thin films which were characterized by Rutherford backscattering spectroscopy (RBS) and Fourier transmission infrared spectroscopy (FTIR). Furthermore, current-voltage characteristics were studied in dark and illuminated environment at room temperature. We studied the variation of photodiode characteristics with the thin film compositions. These results were also compared with the SiCN thin films growth using identical parameters except for the carbon source (CH4 gas) which has been reported in earlier studies2. Our findings showed that the hydrogen content influenced the optical coefficients of these two set of samples. Index of refraction and extinction coefficients were characterized by variable angle spectroscopic ellipsometry (VASE). In addition to our works on developing low-k matrix to enhance the performance of the integrated circuits, the wide gap feature of SiCN thin films enable us to consider the ultraviolet (UV) photo responsivity effect which is studied for photodetector device application.
References:
[1] B.P. Swain, N.M. Hwang, Appl. Surf. Sci. 254 (2008) 5319
[2] Z. Khatami, P.R.J. Wilson, J.Wojcik, P. Mascher, Thin Solid Films 622 (2017) 1–10
Morphology Matters: Additive-Assisted Metal Foam Deposition for the Electrochemical CO2 Conversion
Authors: Dutta Abhijit , Rahaman Motiar , Morstein Carina , Schlegel Nicolas , Broekmann Peter 
Published: February 2020

High-surface area metal foam catalysts for the electrochemical CO2 reduction reaction (ec-CO2RR) are deposited on planar model substrates and technical supports (e.g. 2D mesh or 3D sponges). The metal deposition is typically carried from acidified plating baths at particularly high current densities (e.g. -3 A/cm2) where the metal deposition is superimposed on the hydrogen evolution reaction (HER). Gas bubbles formed on the support surface serve as geometrical template for the metal deposition leaving highly porous metal foams behind.1,2 Pore density and the particular side-wall morphology of these foams can be fine-tuned not only by the current density, metal ion concentration in solution but also by the use of particular polymeric plating additives (e.g. polyethylene-imines, PVPs, polymerizates of imidazole and epichlorohydrin). The activity and product selectivity of the electrochemical reduction of CO2 on Cu foam catalysts strongly depend on the resulting pore size distribution of the Cu catalyst. The maximum in the C-C coupling efficiency (FEC2 = 55%) observed for pore size dimensions in the range of 50 to 100 µm. Such morphology dependence of the ec-CO2RR product distribution will be discussed not only on the basis of the availability of certain reactive surface sites and facets but also on the basis of a temporal trapping of gaseous intermediates (in particular CO and C2H4) inside the mesoporous catalyst material. Mild thermal annealing (300°C, 1h) of the Cu metal foams activates them for the production of C2 and C3 alcohols (ethanol, n-propanol). Identical location (IL) HR-SEM, HR-TEM, white-light interferometry and 3D optical microscopy are applied to probe morphological changes on different length scales that are induced by the foam activation (e.g. by thermal annealing) and the ec-CO2RR itself. This study indicates that the catalyst morphology might undergo drastic changes under operando conditions.
[1] Shin, H. C.; Liu, M. L., Chem. Mater.
2004,
16 (25), 5460-5464.
[2] Shin, H. C.; Dong, J.; Liu, M. L., Adv. Mater.
2004,
16 (3), 237-240.
(Invited) One Step Synthesis of Li-Alkyl Carbonates and Their Applications As Coatings on Li Anode
Authors: Liu Haodong , Zhou Hongyao , Xing Xing , Yan Qizhang , Lee Byoung-Sun , Lim Hee-Dae , Gonzalez Matthew , Liu Ping 
Published: February 2020

Lithium metal is being extensively studied as an anode to replace graphite due to its high capacity and the lowest negative electrochemical potential.1 Current research focus is to mitigate lithium dendrite growth and to increase coulomb efficiency during electrochemical cycling by using various surface coatings or electrolyte additives. Due to the complex reduction reactions of electrolyte components on lithium metal surface, it is highly desirable to develop coating materials with high electrochemical stability.
In this work, we report the synthesis of several Li-alkyl carbonates via a simple one step reaction. These carbonates are known components of solid electrolyte interface (SEI) layers on lithium and graphite anode surfaces. The chemical composition and structural information of these synthetic Li-alkyl carbonates are identified by X-ray diffraction and Infrared Spectroscopy. In one implementation of the reaction, a single-component coating is formed on Li metal in a LiI/organic carbonates (dimethyl carbonate (DMC) and ethylene carbonate (EC)) electrolyte. LiI chemically reacts with dimethyl carbonate to form lithium methyl carbonate, which precipitates and forms a chemically homogeneous coating layer on Li surface. This coating layer is shown to enable dendrite free Li cycling in a symmetric Li||Li cell even at a current density of 3 mA cm-2. Adding EC to DMC modulates the formation of the lithium methyl carbonate, resulting in a stable coating layer which is essential for long term Li cycling stability. Fig.1 shows the morphology of deposited Li using LiI-EC/DMC electrolytes.2 Furthermore, the coating can enable dendrite free, high coulomb efficiency cycling after being transferred to common LiPF6/carbonates electrolytes which are compatible with metal oxide cathodes. We will show that LiI reacts with a broad range of organic carbonates and ethers to form lithium compounds relevant to high efficiency operations of battery anodes.

Acknowledgements

This work was supported by the Office of Vehicle Technologies of the U.S. Department of Energy through the Advanced Battery Materials Research Program (Battery 500 Consortium) under Contract DE-EE0007764.

Reference

W. Xu, J. L. Wang, F. Ding, X. L. Chen, E. Nasybutin, Y. H. Zhang and J. G. Zhang, Energ Environ Sci, 2014, 7, 513-537.

H. D. Liu, H. Y. Zhou, B. S. Lee, X. Xing, M. Gonzalez and P. Liu, ACS Appl Mater Inter, 2017, 9, 30635-30642.

Figure 1
Redox Flow Battery Electrolyte Design Formulations: Molecular Screening and Engineering
Authors: Murugesan Vijayakumar , Wei Xiaoliang , Hollas Aaron , Nie Zimin , Li Bin , Sprenkle Vincent , Reed David , Wang Wei 
Published: February 2020

Redox flow battery (RFB) offers great promise to provide transformational progress for large-scale energy storage technology. As the energy-bearing redox active species are dissolved and externally stored in liquid electrolytes, their physiochemical properties dictate the energy density, specific capacity, and cycle life thereby become a single most critical component of RFB. For instance, the concentration and chemical stability of redox active species within the electrolyte will determine the system-specific energy density and temperature window for the RFB operation, respectively1. With the growing interest in developing sustainable RFB systems, there is a pressing task to identify the optimal electrolyte. This led to an active search for an ideal electrolyte which can hold a higher concentration of redox active species with wide chemical and thermal stability. Most electrolyte research has been focused on the empirical study of the effects of the pH, additives and solvent composition2. Using combined spectroscopic and computational studies we established an electrolyte design formulation based on molecular solvate structure tuning3, 4. This helps us to optimize the solubility and redox potential of redox molecule, exemplifying a generic electrolyte design strategy for RFB (see Figure 1). In this presentation, we will discuss the virtual screening and electrolyte design procedures for selecting functional moieties, additive salt and co-solvent to enhances the much-needed redox molecule solubility and stability.
References

M. Vijayakumar, W. Wang, Z. Nie, V. Sprenkle and J. Hu, Journal of Power Sources 241, 173-177 (2013).

M. Vijayakumar, Z. Nie, E. Walter, J. Hu, J. Liu, V. Sprenkle and W. Wang, ChemPlusChem 80 (2), 428-437 (2015).

K. S. Han, N. N. Rajput, M. Vijayakumar, X. L. Wei, W. Wang, J. Z. Hu, K. A. Persson and K. T. Mueller, J Phys Chem C 120 (49), 27834-27839 (2016).

L. Li, S. Kim, W. Wang, M. Vijayakumar, Z. Nie, B. Chen, J. Zhang, G. Xia, J. Hu, G. Graff, J. Liu and Z. Yang, Advanced Energy Materials 1 (3), 394-400 (2011).

Figure 1
(Invited) Flexible Triboelectric Nanogenerator and Highly Sensitive Pressure Sensor
Authors: Fan Fengru 
Published: February 2020

Transparent electronic devices built on flexible substrates are expected to meet emerging technological demands for the next generation of flexible electronic and optoelectronic devices. A suitable energy source is a vital part for realizing fully self-powered systems. Energy harvesting and conversion technology from environment in which the system will be deployed is a promising route. Recently, we have introduced a new concept
on the basis of triboelectrification and electrostatic induction for successfully converting mechanical energy into electric energy at an energy conversion efficiency as high as 50%. Subsequently, transparent triboelectric nanogenerators (TENGs) using indium tin oxide (ITO) or graphene as electrodes have been demonstrated, which are the only possible power source that light can penetrate through. However, there is a need for a low-cost and large area compatible technology for producing transparent TENGs with high-output power supply, aiming for applications
such as touch screens.
In our previous work, we fabricated a transparent TENG and pressure sensor by using polyester (PET) and polydimethylsiloxane (PDMS) films as flexible substrates to integrate ITO electrodes. It has also been demonstrated that the patterned surface is an effective method to improve the output performance of the TENG. However, realizing such a structure is not trivial in mass production and the patterned structure will reduce the transparency of the device due to the light scattering effect. Here, we present a simple, cost-effective and large-scalable method for fabrication of highly transparent TENGs.
Although triboelectric effect has been known for thousands years, the underlying mechanism is actually very complex and still under debating. The competing possible mechanisms appear to include electron transfer, ion transfer, bond dissociation, chemical changes, and material transfer, and it is likely that different mechanisms may be involved depending on the specific materials and environmental conditions. Usually, it needs specialized equipment to characterize the charged surface and study the mechanism. It is worth noting that the output performance of TENG can directly reflect the capacity of the triboelectrification. Herein, we use this feature to investigate the mechanism of the triboelectrification by examining various factors on the performance of TENG.
Furthermore, another meaningful outcome of our study is that we explore the mechanism from the microscopic and molecular perspective using the methods for surface characterization, which would be beneficial to the improvementand application of TENG at a large scale.
References
F. R. Fan, Z. Q. Tian, Z. L. Wang, Nano Energy 2012, 1, 328-334.
F. R. Fan, L. Lin, G. Zhu, W. Z. Wu, R. Zhang, Z. L. Wang, Nano Lett. 2012, 12, 3109-3114.
F. R. Fan, J. J. Luo, W. Tang, C. Y. Li, C. P. Zhang, Z. Q. Tian, Z. L. Wang, J. Mater. Chem. A 2014, 2, 13219-13225.
Mesoporous Metal Electrocatalysts for the Oxygen Evolution Reaction
Authors: Hayashi Akari , Muto Marika , Sasaki Kazunari 
Published: February 2020

Introduction

Development of anode electrocatalys for the PEM type water electrolyzer is challenging since carbon supports cannot be used in order to disperse small catalyst particles under the high potential condition over 1.5 V. Without carbon supports, electrocatalysts result in relatively low active surface area and low activity. Our group has been working on mesoporous materials for PEFC and has found that mesoporous materials can keep their porous structure even after being built into the device. Based on the similar idea used in our PEFC studies, we propose development of carbon-free mesoporous metal electrocatalysts with high active surface area to increase the efficiency of water electrolyzer cells. In this study, mesoporous platinum and iridium materials were particularly developed, and their oxygen evolution reaction (OER) activity was evaluated.

Experimental method

Mesoporous platinum and mesoporous iridium materials were synthesized using Pt(acac)2 or Ir(acac)3 as a metal precursor and Pluronic F127 as a surfactant. After mixing the surfactant and metal precursor, the resulting mixture was heated up under N2 or Air atmosphere to decompose Pluronic F127 and make the mesoporous structure. Their electrochemical measurements were performed using a common half-cell setup in the solution, in order to evaluate OER activity. The durability against high potential like 1.8 V was also analyzed.

Results and discussion

The resulting platinum and iridium materials were confirmed to have the randomly oriented porous structure constructed by aggregation of Pt and Ir/IrOx nanoparticles, respectively. The pore diameter was found mostly smaller than 100 nm. With these porous metal materials, OER activity was evaluated.
Regarding platinum based materials, the initial activity resulted in the same as a standard Pt/KB electrocatalyst, TEC10E50E, even though ECSA was six times higher for Pt/KB. However, for their durability, as expected, Pt/KB lost most of OER activity owing to carbon corrosion. Consequently, carbon-free porous Pt electrocatalyst with high activity and durability was successfully prepared. Similarly, a porous iridium electrocatalyst has been prepared, and its OER activity will be discussed.