bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Centrifugation Method for the Large Particle Removal from CMP Slurry
Authors: Yoo Jinsu , Lee Dongjun , Yoon Hyunjoo , Jeon Joonbae , Kim Kyoungwoo , Hwang Hasub
Published: February 2020

As device sizes become smaller, to achieve superior flatness which directly related to production yield after CMP (chemical mechanical planarization) process gains more importance.[1]

CMP process is an extensive usage and continuing high growth rates in the semiconductor industry. The scratch due to slurry in large particle is the most challenging issue in CMP process. Even much investigation has been tried to eliminate scratches, the understanding the origins of the scratches during polishing are still needed. [2]

 In this study, we examined the change slurry production process to decrease the scratch by centrifugation.

Fig.1 is a comparison of centrifugal separation step added to the slurry production process flow.

Fig.2 shows transmission electron microscope(TEM) image of slurry particle distribution.

Fig.3 shows large particle count(LPC) and quantity filtration measurement(QFM) data we proposed. According to the results, the large particles were removed by centrifugation.

Fig.4 is the scratch comparison result of the normal slurry and centrifuged slurry.

In experimental results, we found that compared and analyzed that the large particles were separated by measuring LPC(large particle count) and QFM(quantity filtration measurement).

We also found out that the centrifuged slurry was improved in CMP through the scratch evaluation.

REFERENCE

1. P. Singer, “Chemical-Mechanical Polishing : A new focus on consumable”, Semiconductor International, pp. 48-53, Feb, 1994.

2. Y. Li, Microelectronic Applications of Chemical Mechanical Planarization, Chap. 17, pp. 512-516, John Wiley & Sons, New Jersey, 2008.

3. J.-G.. Choi et al, “Analysis of scratches formed on oxide surface during chemical mechanical planarization.” Journal of the electrochemical society 157 (2) H186-H191, 2010.

Figure 1
Electrochemical Accesebility of Platinum Nanoparticles Supported on Anatase TiO2 Using Conductive Carbon Additives
Authors: Sato Saiki , Ishida Takanobu , Ayato Yusuke , Mochizuki Dai , Sugimoto Wataru
Published: February 2020

Degradation of carbon supports at the cathode of polymer electrolyte fuel cells is a critical issue leading to a decrease in activity of the platinum electrocatalysts. Metal oxides based on Ti and Sn have been studied as alternative supports, as they show high stability under severe cathodic conditions.1 However, these metal oxides are typically poorly conductive when compared with carbon support and needs to be either reduced or doped with other metals in order to be able to function as a conducting support. Making an electronically conductive path among nanosized metal oxides with conducting carbon-based materials may offer an alternative approach towards utilization of such non-conducting supports. In this study, we pursued the possibility of utilizing carbon nanotubes (CNTs) as a conducting additive to Pt nanoparticles deposited on non-conducing anatase-type TiO2.

Pt nanoparticles were photo-deposited on anatase-type TiO2 (P25, average particle diameter=25 nm). The amount of platinum on TiO2 was adjusted to be 2 mass%. CNTs were added to a dispersion of Pt/TiO2, adjusted to 20 mass% CNT with respect to Pt/TiO2, and dried to prepare the CNT-Pt/TiO2 composites. The catalyst ink was dropped on a glassy carbon disk electrode (φ= 6 mm, 3.5 µg-Pt cm–2) and dried at room temperature. This electrode was used as the working electrode, and electrochemical studies were conducted with a three-electrode electrochemical cell setup. CO stripping voltammetry in 0.1 M HClO4electrolyte (25°C) was performed in order to estimate the electrochemically active surface area (ECSA) of the platinum nanoparticles.

Figure (a) shows a typical transmission electron microscope (TEM) image of CNT-Pt/TiO2. CNTs form a network-like morphology with Pt/TiO2 particles. The average diameter of platinum nanoparticles determined from 150 particles was 2.9 nm. The specific surface area of the platinum nanoparticles based on the particle size was estimated to be 96 m2 g–1. ECSA was estimated from the oxidation charge of pre-adsorbed CO on platinum surface. The ECSA of CNT-Pt/TiO2 was 63 m2 (g-Pt)–1. Thus, the utilization of the platinum surface was 66% compared with the expected value, i.e. 96 m2 g–1. Although the ECSA of CNT-Pt/TiO2 was lower than Pt/C (83 m2 (g-Pt)–1, platinum particle size of 2.1 nm), the utilization of platinum surface was comparable with that of commercial Pt/C (62%). From these result, it is concluded that an electronically conductive path among platinum supported on TiO2particles was successfully established using a CNT network.

1) K. Sasaki, F. Takasaki, Z. Noda, S. Hayashi, Y. Shiratori, and K. Ito, ECS Trans., 33, 473 (2010).

Figure 1
Investigation of the Sodiation and Desodiation of Hard Carbon By Electrochemical Testing and X-Ray Computed Tomography
Authors: Ledwoch Daniela , Adamson Paul , Brett Daniel J.L , Shearing Paul R. , Kendrick Emma
Published: February 2020

Since the commercialisation of Sony’s first lithium ion cell in 1990, most battery projects have focused on lithium ion technologies. With the rising number of portable devices and requirement for stationary energy storage technologies to support renewable energy generators, the demand for lithium and therefore its costs will increase. Hence, alternatives have to be found to lower the energy storage costs and reduce the requirement for the limited lithium metal resources [1]. Sodium ion technologies offer a cost and safety advantage over typical lithium ion cells [2,3], and sodium is a much more Earth abundant element. Hard carbon is typically used as the anode for most sodium ion systems. Its intercalation properties with Na differ from those of Li and although research on Na ion batteries and hard carbon has been performed previously [4], further work is required to understand the mechanism and limitations of sodium intercalation and deintercalation in different composite electrodes. The influence of electrode parameters such as tortuosity, porosity and volume changes, need to be investigated in more detail in order to tailor the electrode structure and compositions for a particular property requirement, such as rate or capacity, and hence ultimately, application.

This work is based on a commercial hard carbon material. Composite electrodes have been fabricated and characterised in test cells vs. sodium-metal. The differences in particle size, porosity and volume expansion have been investigated using X-ray computed tomography (CT), SEM imaging and electrochemical testing. The changes in the electrode structures during sodiation and desodiation are correlated to the electrochemical behaviour of the composite electrodes; in particular to the polarisation, self-discharge and apparent diffusion coefficients, as measured using potentiostatic and galvanostatic techniques. The aim of this project is to identify the most important parameters within a composite electrode and their influence on the battery performance characteristics, such as rate capability and cycle life. This will help to engineer electrodes for high rate performance and make them more suitable for high power applications or stationary energy storage systems.

[1] T. Hunt, “Is There Enough Lithium to Maintain the Growth of the Lithium-Ion Battery Market?”, Greentechmedia, 2015, web 14/4/16

[2] V. Palomares, et al., Energy Environ. Sci. 2012, 5, 588

[3] J. Barker, M.Y. Saidi and J. Swoyer, Electrochem. Solid-State Chem. 2003, 6, A1

[4] E. Irisarria, A. Ponroucha, M. R. Palacina, J. Electrochem. Soc. 2015, 14, A2476-2482

Figure 1. a) X-ray computed tomography image of an unsodiated hard carbon electrode; b) cross section of a) - visualising hard carbon (grey), larger spots of carbon black/binder (white) and pores (black); c) SEM of hard carbon electrode.

Figure 1
Facile Synthesis of Low and Non-Precious Metal Nanocatalysts for Oxygen Reduction Reaction in Fuel Cells
Authors: Fu Shaofang , Zhu Chengzhou , Song Junhua , Du Dan , Lin Yuehe
Published: February 2020

The considerable interest in polymer electrolyte membrane fuel cells (PEMFCs) has sparked sustained research efforts on more active and stable oxygen reduction reaction (ORR) electrocatalyst. Although great progress has been made on ORR catalysts in recent decades, the further development of PEMFCs is severely restrained by high-priced Pt catalysts and the slow kinetics of the ORR on cathode. Control of nanostructures at the atomic level can precisely and effectively tune catalytic properties of catalysts, optimizing the structural and compositional effect and further enabling enhancement in both activity and durability. Therefore, constructing novel nanocatalysts with low and non-Pt group metal (PGM) has received significant attention to further enhance ORR electrocatalytic performance.

Combining structural, morphological and compositional features, Pt-based alloys with optimized composition and unique structures are expected to present enhanced electrocatalytic performance and economical advantages. On one hand, the electron structure of Pt is modified by the non-precious metals when Pt-based alloys are formed. This modification is efficient to weaken the binding energy between Pt and the adsorbed hydroxyl species. Therefore, more active sites are released, and thus improve the electrocatalytic performance. On the other hand, Pt-based nanocrystals with complex morphologies are promising in catalyzing ORR in fuel cells.

The cost of catalyst can be further reduced by completely getting rid of platinum using non-precious metal nanocatalysts or metal-free nanomaterials. In addition, by introducing heteroatoms, metals, and metal oxides, more active sites are formed for oxygen reduction reactions, and thus improve the catalytic performance of the catalysts.

Significantly, these low and non-precious metal nanocatalysts show excellent electrocatalytic activity and high stability toward to the ORR, holding great promise for the development of PEMFCs.
Rechargable Lithium-Air Batteries: Investigation of Redox Mediators Using DEMS
Authors: Christensen Mathias Kjærgaard , Storm Mie Møller , Norby Poul
Published: February 2020

The rechargeable aprotic lithium-air battery is a promising technology that offers high theoretical energy density of as much 10 times the capacity of current Li-ion batteries. This type of battery technology differs from conventional batteries because of the gas exchange during discharge/charge cycling. Characterizing the gas content during charge using Differential Electrochemical Mass Spectroscopy (DEMS) allows for in-situ characterization of chemistry in the battery.

Using our DEMS setup we have investigated different cathode materials for lithium-air batteries. A carbon black cathode exhibits a flat discharge curve with low over-potentials until the "sudden death" phenomenon which causes the voltage to drop quickly. On the charge side however, this materials exhibits significant over-potentials. These high over-potentials are linked with CO2 development which indicates that the cathode material or electrolyte is being decomposed. This is also seen with Thermally reduced Graphene Oxide (TrGO). The graphene based cathode is interesting as it exhibits a high surface area which in turn increases capacity.

Using the additive LiI, functioning as a redox mediator, the discharge curve remains largely unchanged whilst the charge curve exhibits dramatically lower over-potential, throughout the experiment [1][2]. Under certain conditions the chemistry of the battery changes, resulting in a four electron process that produces the reversible discharge product LiOH rather than Li2O2 which is observed without the redox mediator [2]. This results in higher energy densities and ideally higher cyclability due to the lower over-potentials. Using DEMS we have investigated the gas evolved in the process to determine the electron to oxygen ratio using both cathode materials mentioned.

As has been shown with lithium-air batteries the water content affects the morphology of the discharge product[3]. The effect of changing experimental conditions such as varying water content will be reported.

References

[1] Hee Dae Lim, Hyelynn Song, Jinsoo Kim, Hyeokjo Gwon, Youngjoon Bae, Kyu Young Park, Jihyun Hong, Haegyeom Kim, Taewoo Kim, Yong Hyup Kim, Xavier Lepro, Raquel Ovalle-Robles, Ray H. Baughman, and Kisuk Kang. Superior rechargeability and efficiency of lithium-oxygen batteries: Hierarchical air electrode architecture combined with a soluble catalyst. Angewandte Chemie - International Edition, 53(15):3926{3931, 2014.

[2] Tao Liu, Michal Leskes, Wanjing Yu, Amy J. Moore, Lina Zhou, Paul M. Bayley, Gunwoo Kim, and Clare P. Grey. Cycling Li-O2 batteries via LiOH formation and decomposition. Science, 350(6260):530{533, 2015.

[3] Nagaphani B. Aetukuri, Bryan D. McCloskey, Jeannette M. Garca, Leslie E. Krupp, Venkatasubramanian Viswanathan, and Alan C. Luntz. Solvating additives drive solution-mediated electrochemistry and enhance toroid growth in non-aqueous Li-O2 batteries. Nature Chemistry, 7(January):50-56, 2015.
Estimation of the Cathodic Overpotential for the Double Layer Structure in Pemfcs Using MD
Authors: Nuñez Toledo Laura Elisa , Ribadeneira Paz Rafael Esteban
Published: February 2020

In this work a molecular dynamics (MD) based model is employed to describe and obtain the over-potential in the EDL cathodic structure consisting of the platinum(100)-water-oxygen interface, for Proton Exchange Membrane Fuel Cells (PEMFCs). This approach aims to be integrated in a multiscale model [1], describing the kinetics in the cathodic electrode through density functional theory (DFT) and the macroscopic behavior through a pseudo 2D model for PEMFCs reported in previous works [1]. In the framework of MD simulations, it is required to define an interaction potential model that describes the size, the charge polarization and the chemical characteristics of the electrochemical interface. In this work TIP3P model is used to describe interaction among water molecules, whereas interaction among platinum, water and oxygen is modeled with Lennard-Jones 12-6 model including electrostatic interactions. MD simulations are performed in LAMMPS with a rigid wall of platinum and periodic boundary conditions in x and y directions, using a NPT ensemble to obtain the equilibrium configuration of the system at 1 bar and 353.15K

 The MD simulation allows to obtain the density distribution functions of water molecules and oxygen atoms perpendicular to X-Y plane. Then, the density distribution profiles are used to calculate the charge distribution through formal charge of water and oxygen. Finally the Poisson equation is employed to get the electrostatic potential across the interface and an associated electrostatic over-potential. Also several simulations are carried out at different cathodic current densities. The obtained water density distribution at OCV is validated according to the results of previous works [2-4].

[1] S. Castaneda Ramirez, a. E. Perez Mendoza, és R. E. Ribadeneira Paz, ECS Trans., 66, 19–39 (2015).

[2] X. Xia, L. Perera, U. Essmann, és M. L. Berkowitz, Surf. Sci., 335, 401–415 (1995).

[3] K. Foster, K. Raghavan, és M. Berkowitz, Chem.
Phys. Lett., 162, 32–38 (1989).

[4]E. Spohr, J. Phys. Chem., 93, 6171–6180 (1989).

[5] K. Heizinger, Pure and appl Chem.
63, 1733-1742 (1991).

[6] D. A. Rose, I. Benjamin. J. Phys. Chem
95 (1991).
Praseodymium Doped Ceria Oxygen Surface Exchange Coefficient and Film Stress Measurements Via the Curvature Relaxation Technique
Authors: Ma Yuxi , Nicholas Jason D.
Published: February 2020

Introduction

Praseodymium doped ceria (PCO) is a mixed ionic electronic conductor (MIEC) that can be used as a cathode material in solid oxide fuel cells (SOFCs). Under SOFC operating conditions, PCO undergoes the following reaction [1]:

½ O2 + 2Pr’
Ce + VӦ à 2PrCe + Oo
x

The kinetics of this oxygen exchange reaction are represented by the oxygen surface exchange coefficient (kchem
). In this work, simultaneous kchem
and stress measurements on PCO thin films atop yttria-stabilized zirconia (YSZ) substrates were performed from 625-725 oC using the curvature relaxation (κR) technique.

Experimental Methods

Phase pure Pr0.1Ce0.9O1.95 powder was prepared through glycine nitrate combustion and subsequent powder calcination in air. (001) oriented 9.5% YSZ substrates (Crystec, GmbH) were pre-annealed at 1450oC for 20 hours. PCO thin films were sputtered onto YSZ substrates at room temperature and then sintered for 1 hour at 1100oC. The bilayer structures were tested using a multi beam optical stress sensor (MOSS) from 625oC to 725oC with 25oC increments. The κR technique determines kchem
by fitting a solution of Fick’s 2nd Law to the curvature response of mechano-chemically active film | inert substrate bilayers reacting to sudden changes in oxygen partial pressure (synthetic air (21% O2 - 79% Ar) and 10% synthetic air - 90% Ar) [2,3]. Film stress values were calculated using Stoney’s equation [2,3]. In order to compare the kchem
values with those in the literature, electrically-measured PCO kq
values from the literature [4] were turned into kchem
values by multiplying them by the corresponding PCO thermodynamic factor from Ref [5].

Results

Figure 1 shows how the kchem
value measured via the κR technique compares with literature [4,5] values.

Conclusions

The PCO kchem
and activation energies measured here are significantly different than those reported in the literature. Although additional work is needed before these effects can be explained in full, these discrepancies may be caused by the different synthesis techniques (sputtering vs. pulsed laser deposition) used to produce the two films shown in Figure 1.

 

Acknowledgements

This material is based upon work supported by the Department of Energy under Award Number DE-FE0023315.

 

References

[1] Bishop S R, Stefanik T S, Tuller H L. Journal of Materials Research, 2012, 27(15): 2009-2016.

 [2] Yang Q, Burye T E, Lunt R R, et al. Solid State Ionics, 2013, 249: 123-128

[3] Yang Q, Nicholas J D. Journal of the Electrochemical Society, 2014, 161(11): F3025-F3031.

[4] Chen D, Bishop S R, Tuller H L. Journal of Electroceramics, 2012, 28(1): 62-69.

[5] Chen D, Bishop S R, Tuller H L. Advanced Functional Materials, 2013, 23(17): 2168-2174.

Figures

Figure 1. A comparison of literature and κR-measured PCO kchem
values [4,5].

Figure 1
Bipolar Membrane Fabrication for Hybrid Acid/Alkaline Fuel Cell Systems
Authors: Ahlfield John M. , Liu Lisha , Kohl Paul A
Published: February 2020

Bipolar membranes fuel cells utilizing both anion and cation conductive materials have several advantages compared to their purely acidic or alkaline counterparts. The potential advantages include improved water management through self-hydration and facile electrode kinetics. Material transport properties play an important role in determining viability of membrane and ionomer materials. In addition, the cation-anion junction itself is a critical element in determining device performance because it must be sufficiently conductive to ionic species and mechanically stable to withstand the internal pressure from water formation. A series of electrochemical devices using different bipolar membranes have been fabricated for use in direct methanol and hydrogen fuel cells. This study examines both single- and two-membrane systems containing cation-anion junctions. These fuel cells were characterized by performance metrics and electrochemical impedance spectroscopy to determine specific areas for improvement in the bipolar devices. Operation under varying humidity was studied in order to understand water management necessary for bipolar fuel cells. These results will be used in the future optimization of bipolar devices.

Financial support from US Office of the Deputy Assistant Secretary of the Army for Defense Exports and Cooperation (DASA-DE&C) is gratefully acknowledged.
Bond Order Potential for Two-Dimensional Stanene to Probe Thermal Transport Using Molecular Dynamics Simulations
Authors: Narayanan Badri , Cherukara Mathew , Kinaci Alper , Sasikumar Kiran , Sen Fatih G. , Davis Michael J. , Gray Stephen K. , Chan Maria K. Y. , Harder Ross , Sankaranarayanan Subramanian K. R. S.
Published: February 2020

Recent realization of single layer tin (stanene) on Bi2Te3 substrate via molecular beam epitaxy has led to a surge in research into its fundamental properties, and the feasibility of using stanene for various energy and device applications. In particular, stanene has attracted lot of attention owing to its tremendous promise in topological insulation, large-gap 2D quantum spin hall states, lossless electrical conduction, enhanced thermoelectricity, and topological superconductivity. Most of the previous works on stanene have focused on its electronic properties; atomistic investigations on growth mechanisms (needed to guide synthesis), phonon transport (crucial for designing thermoelectrics), and thermo-mechanical behavior of stanene are scarce. This paucity is primarily due to lack of reliable and efficient potential models that can accurately capture atomic interactions in stanene. Here, we develop a bond-order potential (BOP) based on Tersoff formalism that can accurately capture bond breaking/formation events, structure, energetics, thermodynamics, phonon frequencies, thermal conductivity, and mechanical properties of single layer tin. We determine the BOP parameters by fitting to a training dataset containing (a) structure, (b) equation of state (energy vs area), (c) elastic constants, and (d) phonon dispersion of stanene obtained from our density functional theory calculations. For fitting, we employ a global optimization scheme based on genetic algorithms. Finally, we employed our newly developed BOP to study anisotropy in thermal conductivity of stanene sheets, temperature induced rippling, as well as dependence of anharmonicity and thermal conductivity on temperature.

Figure Caption: Comparison of (a) phonon dispersion, and (b) phonon density of states for monolayer stanene predicted by our newly developed Tersoff potential with those obtained from density functional theory calculations

Figure 1
Facile and Green Synthesis of Carbon-Supported Nanoparticle Catalysts By Physical Vapor Deposition on Soluble Powder Substrate
Authors: Jang Injoon , Park Hee-Young , Park Hyun-Seo , Kim Jin Young , Jang Jong Hyun , Kim Hyoung-Juhn , Sung Yung-Eun , Yoo Sung Jong
Published: February 2020

Recently, Nanoparticles supported on high surface area carbon (NP/C) have attracted increasing interest for application in electrical energy generation and storage systems. NPs/C can be prepared by the chemical and/or physical reduction of metal ions. Typically, impregnation is widely used for preparing supported NPs. Meanwhile, fine metal NPs have been prepared by the physical vapor deposition (PVD) of corresponding metals, in the absence of metal complexes. PVD on liquid substrates, such as ionic liquids (ILs), vegetable oils, and liquid N2-cooled acetone has been reported for the preparation of NPs with a tunable composition and size distribution. However, these approaches require expensive reagents, such as metal ion complexes, solvents, and stabilizing or reducing agents, which often exhibit potential environmental and biological hazards.

In this study, we present a novel, facile and totally green approach toward the synthesis of NPs/C catalyst by using the α-D-glucose (Glu). This strategy consists of: 1) The deposition of NPs on α-D-glucose powder (NP/Glu) by PVD; and 2) Transfer of the NPs from Glu to carbon supports using a mixture of NP/Glu, high surface area carbon support, and solvent. PVD is employed for the facile preparation of various types of NPs, including noble metals, alloys, and transition-metal oxides. The prepared NPs are expected to exhibit a finite size and narrow size distribution. Moreover, our NPs will not contain surfactants, which often impede catalytic reactions. This strategy can be extended to prepare NPs on a range of supports, such as carbon nanotubes (CNTs), graphene oxide (GO), and TiO2, thereby demonstrating its generality. As only the target materials and Glu are required in our procedure, it can be considered environmentally friendly, with the NPs being devoid of hazardous chemicals. In this strategy, Glu act as not only carrier for the transport of NPs from the bulk materials to the support materials but also stabilizer through their OH moieties of the Glu surfaces, which prevent the agglomeration of NPs during the synthesis process. Furthermore, the prepared NPs/C exhibited an improvement in activity for various electrochemical reactions, mainly attributed to their high surface area.
Fabrication and Characterization of Ag Doped CeO2 Nanoparticles By a Hydrothermal Process
Authors: Bae Dong Sik
Published: February 2020

Ag doped nanocomposite catalysts, such as Ag@CeO2, were investigated to evaluate the influence of metal doped morphology on catalytic performance in the antibacteria. The Ag doped CeO2 nanocomposite catalysts were synthesized by hydrothermal process. The catalysts were characterized by use of XRD, antibacteria test, TEM, and TGA. The Ag@CeO2 catalysts with a doped ceria nanostructure exhibited superior catalytic activity over the catalysts prepared by impregnation of Ag on a CeO2 support in solution. The high catalytic activity on a nocomposite catalysts in solution is mainly attributed to the improved surface area by doped ceria catalyst morphology.
Dry Reforming of Methane on Ni@SiO2 Core-Shell Nanoparticles: Influence of Core-Shell Morphology on Catalytic Performance
Authors: Bae Dong Sik
Published: February 2020

Ni-nanocomposite catalysts, such as Ni@SiO2, were investigated to evaluate the influence of core-shell morphology on catalytic performance in the dry reforming of methane (DRM). The Ni-nanocomposite catalysts were synthesized by a combined reverse micelle and sol-gel technique via metal alkoxide hydrolysis and condensation. For comparison, a Ni/SiO2 catalyst was also prepared by the impregnation method. The catalysts were characterized by use of XRD, N2 adsorption, H2 TPR, H2 chemisorption, TEM, and TGA. The Ni@SiO2 catalysts with a core-shell nanostructure exhibited superior catalytic activity over the catalysts prepared by impregnation of Ni on a SiO2 support in DRM. The high catalytic activity on nanocomposite catalysts in DRM is mainly attributed to the improved sintering resistance by core-shell catalyst morphology.
Comparative Study on Synthesis of CeO2-ZrO2 Nanocrystalline Materials
Authors: Ozawa Masakuni
Published: February 2020

Cerium dioxide (ceria; CeO2) has been widely investigated due to high chemical stability, good dielectric strength, oxide ionic conduction, high refractive index and high efficiency for absorbing UV radiation.　Also, ceria zirconia with general formula CexZr1-xO2 is famous as oxygen storage capacity (OSC) material for oxygen storage/release oxygen through redox processes involving the Ce4+/Ce3+ couple. The homogeneity and the phase purity of the products are still uncertain depending on their processing, especially for nanoparticles. The photoluminescence properties of Eu3+ become useful probe to examine a local structure in Eu-doped host material. Although several studies were performed with Eu doped CeO2-ZrO2, there is lack of an investigation on the photoluminescence properties. In this paper, nanocrystalline Eu3+-doped CeO2-ZrO2 were prepared and analyzed by Eu3+ photoluminescence as to their local structural features.
Formation of Nanoporous Electrode on Aligned CNT Films Using Dealloying
Authors: Saito Mikiko , Mizuno Jun , Kusunoki Michiko , Nishikawa Hiroshi
Published: February 2020

Eco-power systems and recyclable energy are in high demand in low-carbon societies for practical applications of power devices. In these power-device fields, there is a requirement for the development of electronic packages for the radiation of heat. Carbon nanotubes (CNTs) have high thermal conductivities, large electron mean free paths, and large maximum current densities, as compared to metals. For these reasons, the application of CNTs in semiconductor packaging and three-dimensional wires is expected. It is reported that CNTs that have high densities and are well aligned are formed by the surface decomposition of SiC, which is the substrate of the power transistor [1]. However, the contact resistance between the CNTs and the electronic circuit is high. On the other hand, metal nanoparticles have been known to possess various properties that are not present in the bulk and are expected to have applications in various fields such as electronics and biotechnology. Metal nanoparticles have achieved low melting points and high chemical reactivity. Lower temperatures for some processes are expected when using nanosized particles. Au is applied in micro/nano electrochemical systems and in biotechnology applications because it exhibits superior stability and conductivity over other metals. Dealloying is the method used to construct a nanoporous structure by the selective etching of the poor metal from a bimetal consisting of a noble metal and a base metal. We have attempted to form nanoporous structures of Au–Ag films using the electrochemical method and a low-temperature dealloying process [2]. We tried to form metal nanoparticles of Au–Ag on the CNTs to get good contact resistance by dealloying. The purpose of this study is to clarify the initial growth mechanism of the electrodeposited films and nanoporous structures on the aligned CNT films, and to propose an electrode structure with good thermal-emission characteristics.

 References

[1] M. Kusunoki, T. Suzuki, T. Hirayama, and N. Shibata, “High-density and well-aligned carbon nanotubes formed by surface decomposition of SiC”, Appl. Phys. Lett., 77, 531-533 (2000).

[2] M. Saito, K. Matsunaga, J. Mizuno, H. Nishikawa, Nano-porous Structure Control under Electrodeposition and Dealloying Conditions for Low-temperature Bonding5th Electronics System-Integration Technology Conference, Category number CFP14TEM-ART; Code 109411. Article number 6962819 (2014).
Advnaced Membrane Technologies to Enable Sustainable Energy
Authors: Herring Andrew M , Motz Andrew R , Sarode Himanshu N , Pandey Tara P , Liu Ye , Divekar Ashutosh , Nguyen Vinh , Kuo Mei-Chen , Horan James L
Published: February 2020

The polymer electrolyte membrane (PEM) is the heart of many low temperature energy conversion devices, such as fuel cell, electrolyzers, and redox flow batterries. The PEM ideally is a perfect separator and facilitates ions to pass to complete the electrochemical reaction and allows water transport either because it is a reactant or for system and materials optimization issues. Water becomes a critical issue; sometimes an ideal PEM should allow ions to move in the absence of water while other applications may require that water move across the membrane at the same rate as the ions. Of course this leads to the realization that new and emerging PEMs will also have great impact on water purification systems. We have been focused on tow systems over the last several years, Proton Exchange Membranes (PrEM) for hotter and drier operation of fuel cells and Anion Exchange Membranes (AEMs) for applications in fuel cells, electrolyzes, and barrier layers.

Our work on PrEMs has focused on making inorganic-hybrid polymers of inorganic super acids by functionalizing them with vinyl groups so that they can be copolymerized with common organic monomers to make hybrid polymers. Both zirconium phosphonates and heteropoly acids have been incorporated into films in this manner. These materials exhibit exceptionally high proton conductivities at 80oC and 95%RH as well as 110oC and 50%RH, making them suitable for incorporation in a wide range of devices. Our work on AEMs, while initially focused on fundamental studies has led to a number of materials with advanced cations that have the chemical stability, high ionic conductivity and mechanical properties to enable the new field of AEM fuel cell and electrolyzers. In this presentation we show the properties that can be obtained and the first device level studies that illustrate the potential of these new materials to solve next generation energy (and water) problems.
Development of Lithium Ion Conducting Glass-Ceramics and Their Properties
Authors: Katoh Takashi , Nakajima Kousuke , Hoffman Brion
Published: February 2020

Solid lithium ion conducting materials have been developed for their potential applications in high energy density batteries and electrochemical devices.1-2) Recently, solid lithium ion conducting materials based on the LiTi2(PO4)3 formula, which possesses a NASICON-type structure, have shown promise as oxide based solid electrolytes.

We have developed lithium ion conducting glass-ceramics with a NASICON type structure for use as a solid lithium ion electrolyte.3-5) The ionic conductivity of the glass ceramics with a Li1+x+yAlxTi2-yGey(PO4)3 composition shows 1×10-4~10-3 Scm-1 at room temperature. Such ceramics have a very stable in ionic conduction. In addition, the ionic conductivity does not decrease, even if it was soaked in an aqueous of Li salt solution6-7), and does not lose mass after being submerged in boiling distilled-water for 1 hour. This type of electrolyte can protect a lithium metal anode from humid air. As a result, the deterioration of materials in the battery is significantly diminished, leading to a longer battery life.

In this presentation, we will report on the development of solid lithium ion conducting glass-ceramics membranes with high ionic conductivity. and Their properties look promising for use as a separator and an electrolyte in high energy density batteries, such as lithium-air and lithium-water batteries.8) We prepared the solid electrolyte membranes based on the Li1+x AlxTi2- yPO4 crystal phase which is synthesized in the Li2O-Al2O3-TiO2-P2O5 glass system and investigated both the electrochemical properties and chemical stability.

References

1) D.Wang et al., Solid State Ionics 283 (2015) 109

2) J.S.Thokchom et al., J.Electrochem. Soc., 155 (2008) A915

3) J.Fu, Solid State Ionics 96 (1997) 195

4) J.Fu, J.Mater. Sci., 33 (1998) 1549

5) Y.Inda et al., J.Power Sources 174 (2007) 741

6) N.Imanishi et al., J.Power Sources  185 (2008) 1392

7) S.Hasegawa et al., J.Power Sources  189 (2009) 371

8) S.J.Visco et al., J.Solid State Electrochemistry 18 (2014) 1443
Gear Train Triboelectric Nanogenerator (TENG) System for Enhancing Power Conversion Efficiency (PCE)
Authors: Choi Dukhyun
Published: February 2020

Triboelectric nanogenerators (TENGs) have great potential to produce electrical energy by harvesting environmental energy from air flow, wind, waves, vibrations and even human motion. Many studies for developing high performance TENGs have been performed and are still on-going. The surface morphology plays a significant role in enhancing output power. Therefore, many studies have focused on the design and synthesis of novel materials to improve the performance of TENGs. Previously, high output power from TENGs has been achieved using high-speed rotating systems, multi-stack systems, and sliding systems. In those TENG systems, high output power was achieved if a high input energy was captured via high contact frequencies or high contact loads. However, it is difficult to constantly supply high energy because the environmental energy depends on region, weather, population and other factors. Furthermore, obtaining high output power based on high input energy can result in low power conversion efficiency (PCE), which is defined as the ratio of output energy to input energy. Therefore, our goal is to improve the output energy using the same materials and the same input energy to provide a high PCE for future TENG systems. In this study, we report such a gear-based kinematic design for a TENG system to enhance output energy at a given input energy. We connect a small gear (i.e., a working gear, r
w) with a moving TENG element, and the working gear meshes with a larger gear (i.e., an input gear, r
in), which is connected to an input source. The frequency of the working gear increases beyond the frequency of the input gear by controlling the gear ratio (r
in/r
w), thus providing enhanced output energy from our TENG system. Finally, we demonstrate the enhanced performance of our gear-based TENG system through the behaviors of capacitor charging. Our results may offer an effective design for TENG systems to generate enhanced PCE for traditional TENGs.

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(SMEQ XXXI ECS Best Student Paper Award) Electrosyntesis of nNnostructured Poly- 4,7-di (thien-2’-yl)-2,1,3-benzothiadiazole (p-DTBT) on Gold Electrodes
Authors: Hernández-Moreno Gibran , Gutiérrez-Granados Silvia , Frontana-Uribe Bernardo A. , Kuhn A.
Published: February 2020

The organic solar cell is a device capable to transform sunlight into electricity, these are composed of an anode, a cathode, an active layer, sometimes between the active layer and the electrodes, two layers of conductive buffer or holes and electrons are also used [1]. The active layer is made of two different materials an electron-acceptor and an electron-donor, in recent years, efforts to optimize the heterojunction have been reported using donor-acceeptor copolymers synthesized using benzodithiophene (BDT), dithienosilole (DTS), or indacenodithiophene (IDT) as donor unit and benzothiadiazole (BT), thienopyrroledione (TPD), or thiazolothiazole (TTz) as acceptor units. These materials can be polymerized by electrochemical methods, nevertheless the deposits are irregular.

Langmuir-blodgett technique (LB) allow make deposits highly structured, these can be used like a template in order to create substrate with controlled architecture [2]. In this work we use the LB technique in order to create deposits of pDTBT ordered.

Gold electrodes of 1*2 cm were used as substrate, on these, five layers of silicon spheres were deposited. Cyclic voltammetry was using in order to deposited pDTBT. 2, 4, 6, 8, 10, 12, 14, 16 cycles were applied, after this the template was removed using HF 15%. Finally the deposits were analyzed by SEM

In figure 1 a) shows voltammograms deposit, b) shows the SEM image of eight cycles of deposition. It is possible see the regular deposit of pDTBT (half pore).

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Effects of Cell Reversal on Li-Ion Batteries
Authors: Nemanick E. Joseph , Wang David , Matsumoto James , Ives Neil
Published: February 2020

Cell reversal in lithium ion (Li-ion) batteries is the condition of the anode electrochemical potential rising above that of the cathode, resulting in a negative voltage measured at the cell level. There are two primary reactions that occur at the anode at high potentials which increase cell impedance: oxidation of copper current collector, and oxidization of the carbonate electrolytes to CO2. At the cathode, the reducing potential can lead to the electrodeposition of copper to form dendrites, which pose a shorting risk if they bridge the anode and cathode. Cell reversal can be caused by poorly matched cells, a failure of the battery management electronics, or a defective cell in a pack. Under these conditions, one or several of the cells can go into reversal causing performance decreases or even a dangerous thermal runaway event. This paper examines a pack of commercial 18650 Li-ion cells in simulated geosynchronous orbit (GEO) test under conditions where one or more cells were forced into reversal.

Panasonic B cells were matched and assembled into a pack to create a virtual cell. Measurements were collected using matched current shunts, and cells were cycled at a 60% DOD, but with only 90% of removed charge replaced each cycle to simulate a battery management system failure. After failure, cells were non-destructively examined using CT X-ray, and then dissected for failure analysis.

The parallel cell pack operated far into reversal, with up to four complete cycles (Fig. 1) completed before all cells shorted. CT X-ray scans of the cells after shorting detectable amounts of copper dendrites in the cell, and demonstrated the first nondestructive test for cell reversal in Li-ion (Fig. 2). Destructive physical analysis of the cells showed extensive copper corrosion at the anode current collector as well as copper dendrites that were found to have fully penetrated the separator in selected areas.

These results show that these cells can operate several cycles into deep reversal without going into thermal runaway, despite the observed growth of copper dendrites which pierce the cell separator. This has strong implications on cell safety and battery management.

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Wearable Fiber-Shaped Solid-State Supercapacitors Based on Hierarchical MoS2 for a Self-Powered Photodetecting System
Authors: Wang Bin , Cheng Jianli
Published: February 2020

Wearable electronics have attracted great attention from both the scientific and industrial areas. To realize real wearable electronics, wearable energy storage devices with high performance, flexibility and safety are required. Solid−State fiber supercapacitors (SCs) meet the requirements for wearable electronics. The bottleneck in this field is how to develop SCs with combined advantages of high specific capacitance, excellent flexibility, lightweight and high conductivity.

 In this presentation, we report a novel flexible all−solid−state fiber SC by using Ti/TiO2/MoS2 coaxial fiber electrodes. The coaxial fiber electrodes consist of hierarchical MoS2 microspheres assembled with nanosheets grown on TiO2 modified Ti wires. This unique electrode leads to high capacitance, high rate charge/discharge ability and excellent cycling stability in the resulting fiber SCs. The symmetrical supercapacitor achieved a specific capacitance of 230.2 F/g, an energy density of 3.4 Wh kg−1 and a power density of 1327.4 W kg−1. Remarkably, the flexible and mechanically stable fiber SCs show outstanding processability in well−controlled ways, including assembled into a stretchable, spring−shaped device and knitted into the fabric to lighten light−emitting diodes. In addition, the fiber SCs can be integrated in a self−powered photodetecting system and power the UV photodetector steadily.
(Invited) In Situ Gas Analysis of Carbon Based Supercapacitor Operating in Aqueous Electrolyte
Authors: He Minlong , Fic Krzysztof , Novák Petr , Berg Erik J. , Frackowiak Elzbieta
Published: February 2020

Carbon based supercapacitors operating in aqueous electrolytes at extended voltage > 1.23 V attract significant attention for next-generation high power, low cost and environmentally friendly energy storage applications. Cell ageing is however markedly pronounced at elevated voltages and results in accelerated overall performance fade and increased safety concerns. On-line electrochemical mass spectrometry, combined with cell pressure analysis, was for the first time used for in situ investigation of degradation mechanisms in aqueous electrolyte/carbon based supercapacitors.

The activated carbon electrodes possess high specific surface area and oxygen-based surface functionalities (mainly phenol, lactone and anhydride groups), which are oxidized already at cell voltage of 0.6 V to provoke the evolution of minor amounts of CO and CO2. Noticeable water decomposition starts at high voltage of 1.6 V with the evolution of H2 on the negative electrode and carbon corrosion on the positive electrode with the generation of CO and CO2. Short-term cycling leads to partly reversible gas evolution/consumption side-reactions giving negligible capacitance. On the other hand, long-term cycling causes irreversible side-reactions, deteriorates the electrochemical performance, and increases the internal pressure of the cell. Repeated galvanostatic cycling (U < 2 V) is confirmed as a more harmful technique for the electrode integrity compared to the voltage holding in a floating test. In situ gas analysis provides valuable insights into electrochemical cell ageing aspects, such as the nature and potential onsets of side reactions. It supplies fundamental understanding of complex reactions and justifying the performance and safety defeat of high energy aqueous supercapacitors.
(Invited) Understanding the Different Steps Occurring during the Charging of Supercapacitors
Authors: Pean Clarisse , Salanne Mathieu , Simon Patrice
Published: February 2020

Supercapacitors, also known as electrical double-layer capacitors (EDLCs), are powerfull and promising electrochemical storage systems and it is still a key challenge to understand better their action mechanisms at the molecular scale. In this work we use a realistic model [1] to investigate by classical molecular simulations the behaviour of EDLCs: carbon electrodes are made of complex CDCs, in contact with either pure or solvated ionic liquid [BMI][PF6]. In addition, the model allows for the polarization of the electrodes. Compared to experimental studies where it is difficult to get quantitative data on what happens inside the electrodes, molecular simulations allow to analyse finely the processes at the molecular scale, since it provides the position of all the atoms along time. Numerous studies on the equilibrium arrangement of the species inside supercapacitors electrodes have therefore already been carried out in our group [1][2].

We started recently to perform out-of-equilibrium simulations, which allowed us for example to calculate the charging time for corresponding macroscopic devices, by using an equivalent circuit model [3]. Furthermore, the evolution of characteristic quantities, such as number of ions inside the electrodes, number of solvation or degree of confinement of the ions [4] can be monitored with respect to time. A glimpse on the reachable results is shown on the figure bellow: a CDC electrode is mapped from the zones of confinement accessible to the ions, previously identified (from less confined to highly confined) as edge, plane, hollow, pocket, and averaged here over time during the whole charging process. By comparing the behaviour of pure and solvated systems charged at different voltages, we are able to conclude on the effects of solvation and of high potentials on the dynamics of charging.

Figure:

Cartography of a CDC electrode (light blue)
from the zones of confinement accessible to the ions, previously identified (from less confined to highly confined) as edge (red), plane (green), hollow (blue), pocket (yellow),

and averaged here over time during the whole charging process.

References

[1] C.Merlet, B.Rotenberg, P.A.Madden, P.L.Taberna, P.Simon, Y.Gogotsi, M.Salanne, Nature Materials, 2012, 11, 306.

[2] C.Pean, B.Daffos, C.Merlet, B.Rotenberg, P.L.Taberna, P.Simon, Journal of The Electrochemical Society, 2015, 162, 5091.

[3] C.Pean, C.Merlet, B.Rotenberg, P.A.Madden, P.L.Taberna, B.Daffos, M.Salanne, P.Simon, ACS Nano, 2014, 8, 1576.

[4] C.Merlet, C.Pean, B.Rotenberg, P.A.Madden, B.Daffos, P.L.Taberna, P.Simon, M.Salanne, Nature Communications, 2013, 4, 2701.

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