bluuebunny/crossref_metadata_2025 huggingface dataset:
Nanotubes Via Vacuum-Supported Suction-System
Authors: Rastedt Maren , Hoogestraat Dirk
Published: February 2020

Carbon nanotubes are versatile applicable. They can be used within measurement instrumentations (as tips for scanning tunneling microscopy), displays (as component for flat and luminous field emission screens) and for the enhancement of synthetic materials (improvement of their mechanical behavior). Furthermore, there are transistors and accumulators made out of carbon nanotubes (CNT).

Due to the versatility and the achievements of CNTs, it is also interesting to manufacture nanotubes and -fibers out of different materials. Martin Steinhart et al. succeeded to fabricate nanotubes and nanofibers out of various polymer materials by template wetting [1-3].

The template wetting is affected by the basic principles of surface coating/wetting and capillarity. The wetting emerges when low-energy liquids like polymer solutions or melts interact with porous substrates with high surface energies like aluminum oxide membranes (AAO) or macro-porous silicon.

After wetting of the membrane walls, the nanotubes or –fibers need to cure before removing the template with sodium hydroxide (when using AAO) or acid.

With help of the template wetting method, it is also possible to manufacture nanofibers and –tubes out of classical bulk-heterojunction solar cell materials (PCBM: Pheny-C61-butyric acid methyl ester and P3HT: Poly(3-hexylthiophene-2,5-diyl)). Therefore a device has been developed, which should be introduced in this paper (Figure 1a)).

With this element (Vacuum-supported Suction-System, VSS) [4], it is also possible to synthesize Core-Shell-nanotubes, it can be used with educt melts as well as educt solutions. Assemblies of well-defined, uniform and almost defect free nanotubes can be synthesized by this method. The VSS facilitates a simple fabrication of nanotubes filled with nanoparticles. Also PCBM/P3HT-Core-Shell-nanotubes are synthesized in this way (Figure 1 b) & c)) and are prepared and optimized for the application within Bulk-Heterojunction solar cells.

Figure 1:
a) Layout of vacuum-supported suction-system, VSS [4], b & c) TEM-images of Core (PCBM, red)-Shell-(P3HT, white)-nanotubes [4]

References:

1. M. Steinhart, J.H. Wendorff, A. Greiner, R.B. Wehrspohn, K. Nielsch, J. Schilling, J. Choi, U. Gösele, Science, 296 (2002).

2. M. Steinhart, J.H. Wendorff, R.B. Wehrspohn, ChemPhysChem, 4 (2003).

3. M. Steinhart et al., Angewandte Chemie International Edition, 43, 1334-1344 (2004)

4. M. Rastedt, „Design und Optimierung organischer Nanoröhrchen (für die potentielle Anwendung in kostengünstigen organischen Photovoltaik-Bauteilen)“, PhD Thesis, University of Oldenburg (2013)

Figure 1
SWCNT-TiO2 Nanocomposite Photo-Anode for Improved Thermal Performances of Dye-Sensitized Solar Cells
Authors: Agarwal Radhe , Sahoo Satyaprakash , venkateswara Rao Chitturi , Katiyar Ram S.
Published: February 2020

In this study, we report a novel single-wall carbon nanotube (SWCNT)-TiO2 composite photoanode with enhanced thermal conductivity for photovoltaic applications. Thermal chemical vapor deposition technique was used for the growth of high quality SWCNTs. Structural and morphological properties of as synthesized SWCNT and SWCNT-TiO2 composites were inspected using ultra-high resolution transmission electron microscope (UHRTEM) and Raman spectrosctopy. Thermal conductivity of pure titania (TiO2) and SWCNT-TiO2 composites were estimated by an optothermal method. Photovoltaic performance of Dye-sensitized solar cell (DSSC) containing composite photoanodes was studied at various temperatures (ranging from room temperature-323K). We observed a notable decline in the overall photovoltaic performance of the DSSC containing pure TiO2 photoanode at elevated temperatures. Whereas, DSSC with composite photoanodes showed a significant improvement in overall photovoltaic performance consistently at room temperature as well as at elevated temperatures that is believed to be due to the existence of SWCNT and provides a conducting pathway to electrons in trap states and which are released at higher temperature and thus, quench recombination more effectively.
Graphene Chemical Modification
Authors: Hernandez Sandra Catalina , Junkermeier Chad , Dev Pratibha , Lee Woo , Robinson Jeremy , Sheehan Paul , Reinecke Thomas , Walton Scott
Published: February 2020

Graphene has been a research focus due to its numerous unique properties which have motivated vast interdisciplinary research in the search of materials for next-generation technologies. With its unique atomically thin nature, graphene has enabled a closer look at material surface interactions and highlighted the importance of surface interfaces, defects and adsorbates. Purposeful and native defects have demonstrated to have advantageous or adverse influences on the chemical, electrical, optical, mechanical and even magnetic properties of graphene. On the other hand, control of the localization of defects and their arrangement onto ordered and extended structures has enabled new graphene-based materials with novel properties.

It is clear that fundamental understanding of the modification of graphene relies on the understanding of the chemical functionalization dynamics, kinetic barriers, chemical transitions, and diffusion energies experienced by the added adsorbates with the graphene surface as well as the influence of the substrate on each.

Plasmas provide both ease and versatility by enabling a single tool process on a wide range of background gases. In particular, electron-beam generated plasmas can introduce different functional groups over a large coverage range with atomic layer precision, allowing for global or local surface chemistry modulation with a large range of functional group types. Here in we demonstrate the effect of functional group type and quantity on chemical and structural changes. In particular, the degree of graphene lattice distortion as they originate for -oxygen, -fluorine, -hydrogen and -nitrogen functionalities with increasing surface coverage, demonstrating chemical and structural dependence on functional group types (F, O, H, N) and substrate interactions.
Wood for Photonics, Batteries and Structural Materials
Authors: Gong Amy ShinHwei , Zhu Mingwei , Li Tian , Shen Fei , Luo Wei , Song Jianwei , Hu Liangbing
Published: February 2020

In this poster, we will display our recent results on multifunctional structures based original wood materials for emerging applications, including transparent wood, wood photonics, and ultra-thick battery electrodes with Na-ion for Grid scale storage. Wood materials cut from trees in various angles have hundreds of straight holes aligned toward the growth direction. Transparent wood samples have been formed by a series of chemical treatment, including lignin removal, whitening, and polymer infiltration processes. Wood slices cut in 45 degree can make super hazy transparent paper after lignin removal without polymer. The transparent wood also has forward light guiding property where incoming light is guided and can pass through the wood sample along the direction of the holes. The carbonized and activated wood samples have excellent specific surface area where the aligned holes are perfect channels for ion transportation. This aligned structure can be applied in Na-ion batteries, flow battery, and microbial fuel cell. Specific process-structure-property relationship will be discussed in details.
Hierarchical Porous Carbon Scaffolds As a Materials Scaffold for the Attachment of Silicon in Lithium Ion Battery Anodes
Authors: Estevez Luis , Jeong Sookyung , Cao Ruiguo , Zheng Jianming , Li Xiaolin , Xu Wu , Zhang Ji-Guang
Published: February 2020

Carbon and carbon-based composite materials have long been an important component in electrodes utilized for energy storage applications. Their widespread use can be attributed to their combination of good electrical conductivity, relative chemical inertness and low bulk material density (~2 g/cm3). For lithium ion battery (LIB) anodes, graphite is typically employed, but silicon has been heralded an excellent replacement candidate due to its very high theoretical capacity (~ 4200 mAh/g—a capacity over ten times greater than that of graphite). A principal obstacle for the practical application of a Si anode is the extreme volume changes (> 300%) during the lithiation process which eventually leads to a pulverization of the Si material. This is particularly true for larger Si particles (> 200 nm), which severely compromises the commercialization of Si based LIB anodes.

Herein, we present our recent work utilizing various carbon-silicon composite materials systems as LIB anodes. We will show that by using a hierarchical porous carbon scaffold with tailorable textural properties such as pore size, surface area and pore volume, we are able to provide silicon nanoparticles with an excellent scaffold for attachment. Furthermore, we will reveal how this tailorable carbon structure can be further modified via functionalization pathways for both the carbon and silicon materials. We will demonstrate how these strategies improved various performance parameters for these LIB anodes; specifically in terms of cyclic performance—a characteristic weak point for silicon-based LIB anodes.
Carbon Nanocomposite for Photo-Energy Conversion
Authors: Shen Yanfei
Published: February 2020

Manipulating molecular interaction and assembly for developing various functional nanostructures with controlled dimensionality, morphology and tailored properties are currently a research focus in molecular science and materials chemistry. Particularly, the self-organization of fullerenes (i.e. C60) to form various functional assemblies has received intense interest since it can provide excellent optoelectronic properties for photo-energy conversion-induced applications such as solar cells and field effect transistors (FET).

A nanocarbon hybrid of SWCNT and alkylated-C60 derivative was constructed as a donor-acceptor pair for photovoltaics and nanodevice investigations. The appropriate affinity of the long aliphatic chains of alkylated-C60 with the SWCNT surface allows solubilization of SWCNT in organic solvents without disturbing their intrinsic electronic structures. Moreover, the supramolecular assembly of alkylated-C60 and SWCNT is expected to show emergent properties such as photo-induced energy/electron transfer between the two components, and water-repellency at surface. Viaa wet process, the nanocarbon assembly-modified transparent electrodes and single-SWCNT-device were fabricated and performed well for photovoltaic studies. In addition, a superhydrophobic surface was facilely fabricated from the same nanocarbon hybrid. The additional surface feature in the assembly provides an extra benefit for their photovoltaic application, i.e., towards the fabrication of water-proof devices.

In addition, the self-organized microparticles of SWCNT and alkylated-C60 can be used as a temperature indicator for the photo-thermal conversion of SWCNT upon near-infrared (NIR) irradiation, where the fullerene microparticles act as a matrix, and SWCNT as an additive. Upon NIR irradiation, the temperature rise can be confirmed via the melt-induced morphological changes of the nanocarbon co-assembly. Since local heating of SWCNT is widely used in biology such as cancer photo-therapies, our results serve as a reminder that NIR irradiation of SWCNT can induce an extreme temperature rise, e.g., 220 ˚C.

References

[1] T. Nakanishi, Chem. Commun., 46, 3425-3436 (2010)

[2] T. Nakanishi, et al., Adv. Mater. 20, 443-446 (2008)

[3] Y. Shen, et al., Chem. Eur. J., 15, 2715-2767 (2009)

[4] Y. Shen, et al., Chem. Sci., 2, 2243-2250 (2011)

[5] Y.Shen, et al., Adv. Optical Mater., 3, 925-930 (2015)

[6] Y. Shen, et al., J. Am. Chem. Soc.
132, 8566-8568 (2010)

Figure 1
Effects of Deposition Temperature on Synthesis of Ultrananocrystalline Diamond/Amorphous Carbon Composite Films on Cemented Carbide Substrate By Coaxial Arc Plasma Deposition
Authors: Egiza Mohamed , Naragino Hiroshi , Tominaga Aki , Murasawa Kouki , Gonda Hidenobu , Sakurai Masatoshi , Yoshitake Tsuyoshi
Published: February 2020

Synthesis of hard carbon coatings on cutting tools is indispensable for machining the nonferrous materials and carbon fiber composites. Diamond, an allotrope of carbon, is classified at the top of carbon coatings for its unique characteristics, it has the highest known hardness and thus provides superior wear resistance. A diamond crystal consists of carbon atoms tetrahedrally bonded with sp3 hybrid bonds. On the basis of its crystal size, polycrystalline diamond is categorized to microcrystalline, nanocrystalline, and ultrananocrystalline diamond. Ultrananocrystalline diamond/amorphous carbon composite (UNCD/a-C) films, wherein a large number of diamond grains with diameters of less than 10 nm are embedded in an amorphous carbon matrix. A high hardness of UNCD/a-C films is attributed to the refinement of grains in nanoscale and its resultant high content of sp3-bonded carbon.

To provide highly energetic carbon atoms and thus sp3-rich amorphous carbon films, cathodic arc discharge has ever been employed. In addition to the merits of cathodic arc discharge, coaxial arc plasma deposition technique (CAPD) has the following distinctive feature: a coaxial arc plasma gun is equipped with an anodic cylinder that can bunch ions ejected from a cathodic graphite rod located inside the cylinder. Owing to this structure, a supersaturated condition with highly energetic ions can be realized, which is desired for the growth of UNCD crystallites

In this work, the influences of deposition temperature on growth and mechanical properties of the UNCD/a-C films were studied. The films were deposited at different temperatures on cemented carbide (WC-6wt.% Co) plate substrates by using CAPD. The hardness and elastic modulus were investigated by nanoindentation. Structural characterizations of the films have been examined by X-ray diffraction, scanning electron microscopy, hard X-ray photoelectron spectroscopy, and energy-dispersive X-ray. The revealed mechanical and structural properties will be presented.
Simultaneous Interferometry and Microscopy Reveal Unexpected Nickel Corrosion Dynamics in Confined Geometry
Authors: Merola Claudia , Cheng Hsiu-Wei , Kristiansen Kai , Chen Ying-Ju , Israelachvili Jacob , Valtiner Markus
Published: February 2020

Corrosion of nickel and its alloys in confined areas remains a serious concern for the safety of structural materials. We uniquely combined white light interferometry and microscopy with high spatial and time resolution for a real-time study of the corrosion mechanism of confined nickel surfaces in alkali metal chloride (e.g., NaCl) electrolytes (c = 1 – 100 mM) at pH = 7. A mica surface is used as crevice former in the electrochemical surface forces apparatus to establish 600-1000 µm2 confined dry areas on extended nickel surfaces. NaCl is the wetting medium of the confined zones and the electrolyte layer spreads out along all the surface. The nickel surfaces form interfacial oxides films at the beginning when no electrochemical potential is applied. Subsequent application of an electrochemical potential ramp from -400 mV to +800 mV initiates severe corrosion of the formed crevices. Surprisingly, the corrosion inside the crevices proceeds as preferential and self-catalyzed “pitting” corrosion (inhomogeneous localized dissolution with the formation of pits) within in the confined zone. Moreover, different behavior of the Nickel corrosion is observed depending on the concentration: inside the confined zone at low concentration (<10mM) and outside the crevice at higher chloride concentrations (>10mM).  Our data reveal a surprising and detailed view into the initial corrosion mechanism of nickel surfaces in confined zones, and may contribute to a deeper understanding and, ultimately, prevention of localized corrosion of other metallic surfaces. A double-layer theory coupled with diffusion-limited effects provides a plausible explanation for the observed phenomena.
Corrosion Behavior of Aluminium Bronze with Addition of Silicon Prepared By Powder Metallurgy
Authors: Zamri Abdul Halim , Zahri Nur Amirah Mohd , Sukiman Nazatul Liana
Published: February 2020

Aluminium bronze (Cu-Al) is widely used in marine application due to its outstanding resistance to corrosion. The addition of alloying elements increases mechanical strength by the formation of heterogeneous microstructures; however this leads to corrosion attack. In order to understand the corrosion behaviour of aluminium bronze alloy, an appreciation of the microstructure is important. There is a gap in the literature regarding the influence of silicon addition on aluminium bronze particularly in corrosion context. In this work, we prepared the aluminium bronze alloys with silicon addition ranges from 0 to 5.0 wt.% by powder metallurgy technique and extensively investigated their corrosion behavior and microstructures. To characterize the corrosion response, electrochemical tests were carried out in sodium chloride solution, supplemented by constant immersion tests and microstructural characterization by means of scanning electron microscopy (SEM). Optical profilometery was used to determine the form and intensity of localized corrosion. The results provide a correlation between chemistry, microstructure and corrosion of silicon containing aluminium bronze.
Corrosion Fatigue Behavior of Low-Carbon Structural Steel in NaCl Solution
Authors: Otsuka Misaki , Tada Eiji , Nishikata Atsushi
Published: February 2020

Corrosion fatigue is one of the environmental degradations of metallic materials and it has become a great concern as the cause of failure of infrastructures such as bridges and offshore structures. Although it is well-known that corrosion can enhance the degradation of fatigue life, the detailed mechanism of corrosion fatigue is still unclear. Therefore, it is needed to clarify the effects of corrosion on corrosion fatigue life and on the behavior of crack initiation and propagation under cyclic deformation. In this study, corrosion fatigue behavior of low-carbon structural steel is investigated by 4-point bending tests in aqueous NaCl.

The material used in this study was low-carbon structral steel (JIS SM490). The chemical composition of the steel is listed in Table 1. The material was heat-treated at 845 OC for 45 min and then quenched in an oil bath. Furthermore, the material was tempered at 550 OC for 60 min and then cooled in a water bath. The mechanical properties of the heat-treated material were evaluated to be 442 MPa of yield stress and 614 MPa of tensile stress. The heat-treated material was machined into a V-notched 4-point bending specimens in the size of 8 mm wide, 100 mm long, and 4 mm thick. The V-shaped notch of 1 mm in depth was introduced at the center of the specimens. The 4-point bending tests were performed in 1 M and 0.1 M NaCl solutions. The applied stress waveform was triangular at the stress ratio of 0.18 and the frequency of 0.167 Hz. The maximum stress applied to the specimens was changed in the range from 500 MPa to 600 MPa.

In this study, fatigue life of the steel was investigated as a function of applied maximum stresses. It was found from the results that fatigue life of the steel was reduced in aqueous NaCl compared with that in air. In addition, the fatigue life in aqueous NaCl was improved by applying a cathodic potential to the steel. These results indicate that anodic dissolution of iron can enhance corrosion fatigue damage of the steel in NaCl environment. In addition, although corrosion fatigue life evaluated in 1 M NaCl was almost the same as that in 0.1 M NaCl, crack initiation was accelerated in 1 M NaCl compared with that in 0.1 M NaCl. This suggests that crack propagation is retarded due to the blunting of crack tips in the higher concentration of NaCl.

Figure 1
Investigation of Electrochemical Properties Between Titanium Scraps and Recycled Titanium
Authors: Jin Yun Ho , Yang Jae-Kyo
Published: February 2020

Titanium has been widely used in various commercial fields. It has high strength, light weight, superior mechanical property at high temperature than any other metals. It also has good bio-compatibility and resistance corrosion property. However, titanium’s high material costs are limited to fields because of It plays a minor role in various applications due to high cost. Usually, thin oxide film were formed on titanium surfaces. The thickness of oxidized films were known as a few angstrom to nanometers.

Here in, titanium and its alloy (Ti-6Al-4V) scraps were collected by manufacturing process to recycle through acid-treatment routes. The acid-treatment process were consists of nitric acid and hydrofluoric acid. For comparison, we oxidized titanium and its scraps in high temperature in furnace and anodized to formed thick oxide films on titanium surfaces.

We analyzed its electrochemical properties by potentiodynamic polarization with potentiostat between scraps and recycled titanium. Ringer’s solution (9 NaCl, 0.24 CaCl, 0.43 KCl and 0.2 NaHCO3 in g/L) were used as electrolyte solution. The saturated calomel electrode (SCE) and graphite rode served as the reference and auxiliary electrodes, respectively. Potentiodynamic polarization tests were carried out at a scan rate of 500 mV/min from -250 ~ 3000 mV vs SCE with corresponds to open circuit potential (OCP).

Figure 1
Local Electrochemical Study of Friction Stitch Welded X65 Steel Using Scanning Vibrating Electrode Technique
Authors: Gu Yanhong , Ma Huijuan , Gao Hui
Published: February 2020

The corrosion of the friction stitch welded (FStitchW) X65 steel has been studied by local electrochemical techniques, namely scanning vibrating electrode technique (SVET) and local electrochemical impedance spectroscopy (LEIS), under 3.5% NaCl solution. The microstructure of the FStitchW X65 pipeline steel was observed by metallographic microscope and scanning electron microscope (SEM). The hardness of the FStichW samples was tested by a digital microhardness tester. SEM and hardness results showed that the microstructure of the welded zone of the FStitchW sample is compact, the hardness is the maximum. SVET and LEIS results showed that for the welded zone the local corrosion potential is the smallest, and the local impedance is the maximum. What leads to the distinguished corrosion resistance of the welded zone superior to base metal and heat affected area is discussed.
Effect of Green Corrosion Inhibitors on the Corrosion Behaviour of Nanocrystalline W-42Cr-5Ni Alloy in 0.5 M NaCl Solution
Authors: Subedi Dhruba Babu
Published: February 2020

A corrosion inhibitor is a chemical substance, which when added in a small concentration to a corrosive environment, effectively decreases the corrosion rate of a metallic substance that exposed to the environment (1). The corrosion control method of metals and alloys using the inhibitors is a fundamental academic and industrial concern that has received a considerable attention nowadays (2). Effects of three eco-friendly green corrosion inhibitors of sodium salts of nitrite, molybdate and tungstate in different concentrations (i.e., 200-2400 ppm) on the corrosion behaviour of the sputter-deposited ternary nanocrystalline W-42Cr-5Ni alloy were studied using corrosion tests and electrochemical measurements in 0.5 M NaCl solution open to air at 25ºC. The use of these corrosion inhibitors enhanced to increase the corrosion resistance properties of the alloys as a result the corrosion rate of the W-42Cr-5Ni alloy was decreased with increasing the concentrations of sodium nitrite from 200 to 2400 ppm as shown in Fig. 1(a). The inhibition action of the tested inhibitors was found to obey the Langmuir isotherm model and the inhibition efficiency was found to increase with increasing the inhibitors concentration. Based on the open circuit potential measurements, the most efficient corrosion inhibitor was found to be sodium nitrite than other sodium molybdate and sodium tungstate in 0.5 M NaCl solution open to air at 25ºC.

 Uhlig, R. W. Revie, Corrosion and Corrosion Control; an Introduction to Corrosion Science and Engineering, 4rd edition, John Wiley and Sons, New York, 2008.

J. Bhattarai, Frontiers of Corrosion Science, 1st edition, Kshitiz Publ., Kathmandu, 2010.
The Synthesis and Anticorrosion Performance of Polyaniline/SiO2 Nanocomposites with Different Wettability
Authors: Zhong Lian
Published: February 2020

In this paper, Polyaniline/SiO2 (PANI/SiO2) nano-composites with different wettability were prepared by a “template-free” method, and the anticorrosion properties of the products were investigated. The morphology, wettability, structure of PANI/SiO2 nano-composites have been characterized by various test means including conduct angle measurements, SEM, TEM, XRD and FTRI. The results show that the different synthesis conditions have a great effect on the wettability of PANI/SiO2. When SDS and SiO2
amount is controlled within a certain range, micro/nano double rough PANI/SiO2 with hydrophobic surface can be obtained, and the biggest conduct angle of the nano-composites is 146.3°. SEM and FTIR spectra measurements show that PANi and nano-SiO2 particles are not simply blended or mixed up, and there is a strong interaction between polyaniline macromolecule and nano-SiO2 particles. The corrosion protection performance of the PANI/SiO2 with different wettability was evaluated in 0.1 mol/L H2SO4 by open circuit potentials measurements (OCP) and electrochemical impedance spectroscopy (EIS)．Super-hydrophobic PANI/SiO2 micro/nano structures show better anticorrosion properties than that hydrophilic ones．This is due to the super-hydrophobic PANI/SiO2 coating not only inhibited water from being absorbed by the coating，thus preventing the corrosive chemicals and corrosion products from diffusing through the coating，but also promoting a thin oxide film on the stainless steel surface．

Figure 1
The Adsorption and Corrosion Inhibition of Some Nonionic Surfactants on Carbon Steel and Brass in Aggressive Media
Authors: Branzoi Florina , Pacuretu Catalina , Branzoi Roxana
Published: February 2020

The corrosion inhibition properties of some nonionic surfactants: Triton X100 and Triton A20, for two carbon steels (OL 37 and OLC 45) and brass in 1M H2so4 and 1M HCl was analyzed by weight loss method, potentiostatic and potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and metallurgical microscopy techniques.

The addition of the organic inhibitors led in all the cases to inhibition of the corrosion process in acidic solution at different temperatures. Under the critical micelle concentration (CMC), the inhibition of these three surfactants is negligible and at a concentrations higher than the CMC, the inhibiting action of these inhibitors increases rapidly.

The inhibition activity analysis of these organic inhibitors was made by assuming that the mechanism of inhibition by organic molecules is chemisorptions and physisorptions. We presume that, these organic compounds inhibit corrosion of carbon steels and brass by a protective mechanism, forming insoluble iron complexes, copper complexes and repairing the porous oxide layers. Polarization curves indicate that they are mixed type of inhibitors. The corrosion parameters obtained from polarization curves and from EIS spectra are in good concordance and point out the inhibitory action of cationic surfactants. The inhibition efficiency was high in all the studied cases. The adsorptions of the organic compounds on the carbon steels surface obeyed Langmuir’s isotherm. The thermodynamic parameters of adsorption enthalpy (ΔH0), adsorption free energy (ΔG0) and adsorption entropy (ΔS0) were calculated. The characterization using Fourier transform infrared spectroscopy (FT-IR) demonstrates the adsorption of organic inhibitors and the formation of corrosion products on the carbon steels and brass surfaces. The inhibition process was attributed to the formation of the adsorbed film on the metal surface and blocking the active sites that protects the metal against corrosive agents. The EIS measurements have confirmed this protection and pointed out the formation of adsorption layers on the electrode surface.
Flux Growth and Electrochemical Characterization of Composite Electrodes of LiCoO2 crystals/Li3BO3 glass/Li6.75La3Zr1.75Nb0.25O12 crystals for All-Solid-State Libs
Authors: Zettsu Nobuyuki , Onodera Hitoshi , Kaneko Sakina , Yamada Tetsuya , Teshima Katsuya
Published: February 2020

Tightly connected interface between individual active material particles and solid state electrolytes with large surface area is strongly required for the achievement of high-performance all-solid-state Li ion rechargeable batteries (ASS-LIBs). In this work, we performed flux growth of Li3BO3/Li6.75La3Zr1.75Nb0.25O12 composite electrolytes and LiCoO2/Li3BO3/Li6.75La3Zr1.75Nb0.25O12 composites electrodes under various composition rate at 1000 oC.Powder XRD profiles and cross-sectional SEM images revealed that individual LiCoO2 and Li6.75La3Zr1.75Nb0.25O12 single crystals were homogeneously dispersed in amorphous Li3BO3 matrix without formation of any sub-phase at the interphase even though the crystal growth process was performed under 1000 oC for 5h. The each crystals size and the relative density of the composite was increased as increasing time and temperature. The relative density was maximally 92%. Indicating that small volumetric amount of Li3BO3 plays a key rule for insulating the direct contact of LiCoO2 with Li6.75La3Zr1.75Nb0.25O12 as well as for assisting the enhancement of relative density of composites relied on liquid-state sintering principle. The Li ion conductivity of the composite electrolyte with ca. 700 mm thick was 2.0×10-4 S/cm at room temperature, and the composite electrodes with ca. 700 mm thick was 1.1×10-4 S/cm, as evaluated by AC-impedance spectroscopy. We believe that the flux co-growth of LiCoO2 single crystals and Li6.75La3Zr1.75Nb0.25O12 single crystals in a molten Li3BO3 glass resulted in the formation of smart interface which provide efficient Li+ transfer. We also characterized their all-solid-state LIBs properties.
Nonlinear Cycling Aging of a Commercial 18650 Lithium Ion Cell
Authors: Wu She-huang , Lee Po-Han
Published: February 2020

The capacity and power loss are usually observed when lithium ion batteries were cycled or stored, however, the degradation mechanisms and their correlation with cell performance fade are not only dependent on the cell chemistry but also on the cell design and manufacture technique. The capacity loss diagnosis and the lifetime prediction for LIBs are still critical issues for large format applications. Commercial 18650 lithium ion cells containing a composite cathode of LiNi0.5Mn0.3Co0.2 (NMC) and LiMn2O4 (LMO) and graphite anode with a nominal capacity of 2.15 Ah were used in this study. Although the aging behavior of the battery comprised with LiNi1/3Mn1/3Co1/3O2/LiMn2O4 composite cathode and graphite anode cycled between 4.2 and 2.8V had been studied with an incremental capacity technique and suggested that there are two stages of capacity fade with first stage mainly caused by the loss of inventory (LLI) and further suffered from loss of active material (LAM) in positive electrode in the second stage [1, 2]. The results of capacity retention study within the voltag
e range between 4.2 and 2.75V by following the manufacturer’s suggestion and charging the cells with CC-CV mode with 0.5C rate (cut-off at 0.04C) and discharging at 0.5, 1.0, and 2.0C rates, respectively, shown in Fig.1 (a), manifest that the cells cycled at higher discharge rate exhibit longer cycle life than that cycled at 0.5C. It is contrary to the generally accepted notion that high C-rate will accelerate cell aging. However, the expected tendency can be observed when cells were cycled between 4.2 and 3.0V (Fig. 1 (b)). From the results incremental capacity analysis (ICA) for the charge/discharge curves of the cells discharged at 1.0C rate with lower cut-off voltage of 2.75 and 3.0V, respectively, the redox peaks at around 3.53V, those relates with the amount of active graphite, decreases abruptly after 300th cycle where the accelerated capacity fade occurs for cell cycled between 4.2 and 2.75V.That suggests the accelerated capacity loss can be caused by loss of anode material instead of cathode material in additional to the continued loss of lithium inventory that can be observed from the shifting of the peak at around 3.53V to higher voltage and lowering of the peak at about 3.69V (Fig. 2). In order to understand the non-linear capacity fade when cells were cycled between 4.2 and 2.75V, post-mortem studies with XRD, SEM, ICP, and capacity retention for the electrodes obtained from fresh, 200 cycled, and aged cells will be performed for comparison with those of the cells cycled within 4.2 and 3.0V to support the results obtained from ICA.

Reference

[1] M. Dubarry, C. Truchot, M. Cugnet, B.Y. Liaw, K. Gering, S. Sazhin, D. Jamison, C. Michelbacher, Journal of Power Sources, 196 (2011) 10328-10335.

[2] M. Dubarry, C. Truchot, B.Y. Liaw, K. Gering, S. Sazhin, D. Jamison, C. Michelbacher, Journal of Power Sources, 196 (2011) 10336-10343.

Figure 1
Soft Conductive Carbon Enables Depolarization of LiFePO4 Cathodes to Enhance Both Capacity and Rate Performances of Lithium Ion Batteries
Authors: Wang Kai , Yang Jinlong , Ren Wenju , Pan Feng
Published: February 2020

Conductive nanocarbons generally are used as the electronic conductive additives to contact with active materials to generate conductive network for electrodes of commercial Li-ion batteries (LIBs). In this work, conductive nanocarbons are systematically studied and classified as “hard” and “soft” conductive-carbons (named as HCC and SCC), respectively for the first time according to their structures and morphologies. SCC can create larger contact area with active particles of electrodes because it has more percentage of graphite-like (sp2) structures, smaller crystallite size and larger specific surface area than that of HCC. LiFePO4 (LFP)，which has been widely used as cathode materials for EV LIBs with low electronic conductivity, need to contact with conductive network closely to depolarize for cathode electrodes. It is found that LiFePO4 nano-crystals with large contact area wrapped in SCC networks perform significantly enhanced both capacity and charge-discharge rate capacity than that in HCC for the cathode of LIBs. Combined experiments with multiphysics simulation, the mechanism is investigated that LFP nanoparticles embedded with large contact areas enable to generate depolarization networks and enhance the electrochemical performance with a relatively uniform current density vector () and lithium flux vector (). This discovery will guide us to design LIBs with the high energy and power densities for electric vehicles (EVs) applications.
Enhancement of High-Voltage Cyclability and Rate Capability in LiNi0.5Mn1.5O4cathodes
Authors: Teshima Katsuya , Satoshi Kida , Kim Dae-wook , Zettsu Nobuyuki
Published: February 2020

Lithium ion secondary batteries are one of the most important energy storage systems because of their higher energy density and power density. In particular, many different types of cathode materials are studied for increasing capacity and cell potential. Spinel-type LiNi0.5Mn1.5O4 have been attracting significant attention due to higher redox potential, lower cost and low environmental load. The LNMO is possibly sorted into two type of spinel structure with different space group, ordered and disordered phase, which is typically identified due to formation of oxygen deficient, which cause reduction of Mn4+ to Mn3+ based on charge valance.     

Disordered spinel structures could also lead to improved rate capability due to higher electronic conductivity and Li-ion diffusive of Mn3+ ion, However, too much concentration of Mn3+ lead to structural distortion and disproportionation, and which can be reduce cyclability. Thus, suitable Mn cation adjustment as well as surface stabilization with thin layer for insulating the direct contact with liquid electrolyte is one of important factor for advanced LiNi0.5Mn1.5O4 electrode.  

In this work, we performed two ways for the enhancement of high-voltage cyclability and rate capability in LiNi0.5Mn1.5O4crystals through the substitution of F anion within oxygen deficient LiNi0.5Mn1.5O4-

d
.crystals as well as surface modification with self-assembled monolayer of fluorocabon containing organosilane compound. We further calculational studies on the effect of fluorine substitution on their LIBs characteristics, including rate capability and cyclability by using first-principle calculation.
Potential Tuning in the Benzenedicarboxylate System for Improved Organic Negative Electrodes
Authors: Lakraychi Alae Eddine , Dolhem Franck , Becuwe Matthieu
Published: February 2020

Lithium-ion batteries (LIBs) represent one of the most successful battery chemistry with a range of applications starting from small portable electronic devices to advanced electric vehicles. The increasing demands concerning these large-scale applications have generated intense requirements of improved safety, low costs and of course high energy densities. Anode materials generally used in commercial LIBs, i.e. carbonaceous materials, have a very low operating potential (~ 0.1 V vs. Li+/Li) which cause some safety and cost issues.

As an alternative, several anode materials have been proposed, such as spinel lithium titanate (Li4Ti5O12) which can operate at potentials of 1.0-1.6 V vs. Li+/Li, this fact leading to a decrease of the cell voltage, or such as Si and SnO2, which are confronted to huge volume variation and structural reorganization during charge-discharge process.

In order to achieve the required improvements, anode materials must operate at an intermediate operating potential (0.5-1.0 V vs. Li+/Li). In addition there is a growing interest in designing greener LIBs.  In this context, organic carboxylate-based derivatives have been considered as promising materials for the next generation of such greener LIBs due to their structure based on relatively naturally abundant atoms like C, H, O or N, their possible flexible molecular design, ease of recyclability and especially their operating potential allowing to substitute copper-based current collector by aluminum, thus inducing a drastic cost and weight reduction.

We will present an electron-donating substitution approach with the aim to decrease the operating redox potential in benzenedicarboxylate systems. More precisely, dilithium DiMethylTerepthalate compound (Li2-DMT) was synthesized, fully characterized and evaluated electrochemically as an anode material for Li-ion storage system. This new carboxylate-based material shows promising electrochemical performance, noticeably a stable cycling performance, high thermal stability and an operating potential of 0.65 V vs. Li+/Li, (i.e., -110 mV in comparison with Li terephthalate).

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The Performance of Lithium Bis(trifluoromethanesulfonyl)Amide in Propylene Carbonate on Binder Free Graphite Electrode
Authors: Pan Yue , Lucht Brett L
Published: February 2020

An investigation of the performance of different concentrations of bis(trifluoromethanesulfonyl)amide (LiTFSA) in propylene carbonate (PC) on binder Free(BF) graphite  electrode is studied. The changing of electrolyte concentrations results in a change in the reduction at the electrode interface and the reversible cycling of the cell. For a further study, the electrochemical behavior of LiTFSA in PC as electrolyte for lithium-ion rechargeable batteries is investigated by galvanostatic discharge/charge measurements and cyclic voltammetry, and the structure of the solid electrolyte interface (SEI) at the surface of binder free graphite electrode is characterized by fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). With the increasing concentrations of LiTFSA/PC electrolytes, BF graphite electrodes reveal reversible lithiation/delithiation of graphite instead of continuous electrolyte reduction.
Li-Sulfur Chemistry: Challenges and Opportunities
Authors: Moganty Surya
Published: February 2020

Despite the excellent specific capacity (1672 mAh/g) and energy density (2567 Wh/kg), sulfur has several challenges that prevent the material from achieving commercial status. The primary setback with sulfur is its insulating property. The second detrimental problem is the dissolution of intermediate charge/discharge lithium polysulfide (Li2Sx) products in the electrolyte that leads to decreased utilization of sulfur, triggering parasitic side reactions with Li metal anode, poor cycle life. Hence, the design of electrolytes with lower solubilizing power for Li2Sx is perhaps the most straightforward and valid approach to suppress Li2Sx deduced redox shuttle. A liquid electrolyte designed for this purpose should act as a poor solvent for all of the Li2Sx species of the sulfur cathode, while enabling good Li-ion conduction by the originally doped Li salts. Given that the active species exhibit a wide range of hydrophilic−hydrophobic character: sulfur (hydrophobic, soluble in nonpolar solvents), lithium sulfide (soluble in highly polar solvents) and polysulfide species (intermediate solubility depending on the chain length). At NOHMs Technologies Inc, we have been developing functional ionic liquids as electrolyte additives in conjunction with novel cathode architectures to improve the Li-S battery performance. NOHMs has already demonstrated Li-S pouch cells that has exhibited full-cell specific energy density above 300 Wh/kg and excellent abuse tolerance during standard nail penetration tests.  Figure 1 depicts the NOHMs Li-S cell level performance. This presentation will focus on the ongoing R&D work at NOHMs in maturing the Li-S battery chemistry.

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Effects of Polymeric Layers on Li Depletion and Electrochemical Performance of Li-O2 Rechargeable Batteries
Authors: Jang Il-Chan , Ishihara Tatsumi
Published: February 2020

Li‒O2 batteries have received enormous attention as alternatives to current state-of-the-art rechargeable Li-ion batteries because of their high theoretical specific energy density. However, there are still substantial technical obstacles to developing a practical battery. One of the most significant challenges arise from reactivity of Li metal anode resulting in Li depletion such as solid electrolyte interphase (SEI) and Li dendrite formation. Most approaches to reduce Li depletion focus on adjusting electrolyte components, additives and mechanical barrier. On the other hand, extremely high capacity from a cathode in Li-O2 batteries needs much higher Li utilization of an anode. High Li utilization accelerates Li depletion seriously and consequently results in poor electrochemical performance including cycle stability. Therefore, it is recommended to study on Li depletion and its prevention in more detail for rechargeable Li-O2 batteries.

 In this study, effects of polymer coating layers on the cycle stability were investigated. Li metal adopting poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) highly and effectively increased the cycle stability of a Li-O2 battery. The introduction of this polymeric layer, which exhibited sufficient mechanical strength, suppressed the needle-like dendrite formation. This indicates that the coating may prevent shape changes of the metal during discharge and charge cycles. It was found that improved reversibility of Li redox was achieved by coating with PVdF-HFP polymer.
Spheroidization of Graphite As Anode Material for Li-Ion Batteries: Spheroidization Process and Material Texture and Morphology
Authors: Rapp Manfred , Mundszinger Manuel , Farsi Sarvenaz , Golla-Schindler Ute , Kaiser Ute , Wachtler Mario
Published: February 2020

Natural graphite (NG) is the dominant anode material for lithium ion batteries (LIBs) today, with a market share of approx. ~55%. With the continuous growth of portable, automotive, and other applications the total LIB market is expected to double within in the next decade. In view of this growth scenario, some prognoses predict supply bottlenecks of NG. Furthermore, the NG sources are geographically strongly concentrated today, which poses an immanent risk to supply security. In principle, the increasing demand for graphite as LIB anode material can be met by synthetic graphite, for which an upscaling of the production capacity is possible with economically justifiable effort within short time. Nonetheless, there are strong activities to develop new sources of NG. To benchmark the quality of these new materials, convenient and cost-effective characterization methods and facilities are required.

Pristine flat flakes of NG are usually mechanically turned into spherical shapes (“spheroidization”) and coated with a thin film of amorphous carbon, in order to alleviate problems with exfoliation due to electrolyte solvent co-intercalation during lithium intercalation, to decrease the surface area and thus the irreversible capacity in the first charge/discharge cycle, as well as to increase density and thus the volumetric capacity. Recently, spheroidization is also more and more applied to synthetic graphite materials. Characteristic of the spheroidization procedure is that the yields are usually around 50% only. Any process improvement will therefore have a strong economic impact.

The present work focuses on the lab-scale reconstruction of the industrial spheroidization and fractionation processes, using a rotor impact mill, an air jet sieve, and an air classifier. The aim is:

to obtain a better understanding of the spheroidization process, by identifying critical process parameters and their influence on the resulting products (spherical graphite particles as well as by-products),

to identify potentials for improving the process (especially in terms of yield), and

to offer the opportunity to benchmark graphitic materials in lab-scale in comparison to industrially manufactured references.

The obtained materials are analysed with regard to their electrochemical performance, as well as to their particle morphology (particle size distribution, particle shape, tap density and texture). The microstructure and texture is studied by SEM and FIB/SEM tomography, which provide information on the outer appearance in the nm scale and the open and closed porosity of the materials (Fig. 1).

Acknowledgement:

The authors are indebted to the German Federal Ministry of Education and Research (BMBF) for financial support (Project: Li-EcoSafe, contract no. 03X4636).

Figure 1