bluuebunny/crossref_metadata_2025 huggingface dataset:
CNT/Co3O4 Based Air Electrode Selectively Wrapped By Polyaniline for High Performance Air Electrode
Authors: Kim Jin Young , Park Yong Joon
Published: February 2020

Li-Air battery is one of the most promising new energy storage systems because they provide much higher energy densities than lithium-ion batteries. Nevertheless, Li-air batteries have several issues to be solved before the commercialization. One of them is side reaction attributed to the reaction between carbon, a general component of the air electrode, and electrolyte/Li2O2. Actually, carbon with high surface area provides a large reaction sites to form and store the reaction products. And it compensates for the low electronic conductivity of oxide catalysts such as MnO2 and Co3O4. However, some studies have suggested that the carbon promotes side reaction such as electrolyte decomposition and formation of Li2CO3. The unwanted reaction products formed from side reaction is hardly decomposed on charging process. This results in the accumulation of reaction products on the surface of electrode during cycling, which leads to limited cycle life and high over-potential. As a new approach to address these issues, nano-sized cobalt oxide (Co3O4) particles were composited with carbon nanotube (CNT) to enhance the catalytic activity, and the surface of carbon nanotube was selectively wrapped with polyaniline, a conducting polymer, to suppress the side reaction between carbon (CNT) and electrolyte/Li2O2. CNT/Co3O4 based air electrode selectively wrapped by polyaniline is expected enhanced cyclic performance and low over-potential due to synergic effect of nano-sized Co3O4 catalyst composited with CNT and polyaniline coating layer on the surface of carbon.
Improvement of a Capacity Utilization By Introducing an Asymmetric Anolyte/Catholyte Volume in Vanadium Redox Flow Battery
Authors: Park Jong Ho , Yang Jung Hoon
Published: February 2020

As large-capacity energy-storage systems, redox flow batteries have received considerable attention because they can effectively decouple the power density and energy capacity. The power density is determined by the battery stack design while the energy capacity is affected by the amount of redox species dissolved in the electrolyte, which is circulated through the stack and stored in the external reservoirs. The crossover of the redox species between the anolyte and catholyte within the stack causes the self-discharge and decreases the energy capacity. Vanadium redox flow battery employs the same vanadium ions as the redox species in both anolyte (V2+/V3+) and catholyte (V4+/V5+). Therefore, it can partially solve the crossover problem only by remixing and separating the anolyte and catholyte. However, the frequent remixing reduces the system efficiency significantly. Furthermore, the different transfer rates of each vanadium ions through membrane accelerate the crossover, thus resulting in the capacity decay. The diffusion coefficients were in the order of V2+ > V4+ > V5+ > V3+ across Nafion 115 membrane. Minimizing the capacity decay is very important to improve the real energy density of the flow battery. We have observed an interesting point in the relation between the capacity decay and initial volume ratio of the anolyte and catholyte. At a constant volume of the catholyte, the capacity decaying rate was independent of the anolyte volume. On the other hand, the capacity decay was improved with the decreasing volume of the catholyte at a constant anolyte volume. In this study, we have investigated the dependency of the capacity decay on the initial volume ratio of the anolyte and catholyte.
Sulfides Electrolytes for All Solid State Metal Ion Batteries
Authors: Chen Hailong , McDaniel Malte , Xiong Shan , Wang Hai
Published: February 2020

Replacing the organic, liquid, flammable electrolytes in conventional lithium ion batteries with inorganic, solid, nonflammable electrolytes can potentially eliminate the fire hazard of the batteries. Solid state batteries may also use simpler and lower cost manufacturing methods than what has been used for conventional lithium ion batteries. However, the development of solid state batteries previously has been limited by the low ionic conductivity of the solid electrolytes. Recently discovered superfast ionic conductors such as Li10GeP2S12 (LGPS) and Li10SnP2S12have demonstrated solid state electrolyte can have comparable or even higher Li ion conductivity than commercial liquid electrolyte. All solid state batteries with using sulfide electrolytes has also been reported by Kanno et al. with very high rates at room temperature and elevated temperatures.

Currently many sulfides showed high Li and Na conductivities than their oxides counter parts. However, in general, sulfides are much less explored than oxides. Novel sulfides with good ionic conductivities may exist in the previously unexplored regions in the phase diagrams. We aim to design and discover novel sulfide Li and Na ionic conductors by systematically exploring a number of selected Na(Li)-M1-(M2)-S ternary and quaternary phase diagrams combining conventional solid state synthesis and variable temperature in situ XRD for synthesis. In this work, we report the synthesis, in situ XRD study and electrochemical testing of several sodium tin sulfides as solid electrolyte for sodium ion batteries. Na4SnS4 was synthesized by solid state reactions in pure phase. In situ XRD study on the synthesis process were used to reveal the formation mechanism of this compound. The Na ion conductivity of this compound at various temperatures was measured by using electrochemical impedance spectroscopy (EIS). The relationship between the conductivity and synthesis condition and starting materials are discussed. Several other sulfides were also successfully synthesized in pure phase. Their conductivities were also measured and compared with Na4SnS4. These novel Na ion conductors provide new promise for developing high performance all solid state sodium ion batteries.

Figure caption:

Figure 1. in situ X-ray diffraction patterns of the solid state synthesis process of Na4SnS4sample.

Reference:[1] Y. Kato, S. Hori, T. Saito, K. Suzuki, M. Hirayama, A. Mitsui, M. Yonemura, H. Iba, R. Kanno, High-power all-solid-state batteries using sulfide superionic conductors, Nature Energy, (2016) 16030.

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Developing Solid-State Lithium Ion Battery with Oxide-Based Electrolytes
Authors: Kang Byoungwoo
Published: February 2020

Our society faces energy challenges which are caused by the burning of fossil fuel. As a result, we face serious climate change. To address these challenges, fossil fuel’s energy paradigm should be transformed into sustainable one through further utilizing renewable sources like solar power and wind. However, intermittent property and low quality of renewable sources make their utilization difficult. Energy storage technologies can be a key player for transforming fossil fuels energy paradigm into sustainable energy one by extending the utilization of renewable sources like wind and solar power and by utilizing electric vehicles. The advent of novel applications such as energy storage system for renewable sources and electric vehicles makes present LIB technologies challengeable because these large-scale applications need much demanding requirements than those in portable devices in terms of safety, cost, and cycle life. There are several approaches for solving these demanding requirements. One of promising approaches is the use of solid electrolyte that can bring up several opportunities. For example, solid electrolytes have large stable electrochemical window which can allow us to utilize known materials with high voltage resulting in high energy density without causing any safety problem. In this talk, I will discuss about interface reactions between Nasicon-type or Garnet-type solid electrolytes and composite electrode or Li metal and talk about the developing solid-state battery with these electrolytes.
Ion Trap Micro-Fabrication on High Reflective Coatings
Authors: Arrington Christian L. , Finnegan Patrick Sean , Hollowell Andrew E , Maunz Peter L. , Kim Jungsang
Published: February 2020

Electrochemical fabrication offers unique advantages for nano/microfabrication of 2D and 3D microsystems. Precise control of deposition molds and thicknesses allows significant challenges to be solved through electrodeposition that are beyond the capabilities of standard silicon methods and conventional machining techniques. Previous work has enabled enhanced measurement techniques and reduction of anomalous motional heating in surface electrode ion traps1. This talk will focus on a recently designed two layer ion trap fabricated on top of a high reflective (HR) coated substrate creating a cavity beneficial to interrogating the ion. First, a lift-off profile lithography mold is patterned on a HR fused silica substrate, then a thin gold metal layer is deposited 1-2 micron in thickness, and finally a 10 micron thick electroforming process defines the second layer features. The effects of processing lithography molds on a surface that is highly reflective at the same wavelength used for the lithographic patterning will be presented. These details, along with a second layer of patterned gold, will be characterized using scanning electron microscopy, profilometry, and energy dispersive spectroscopy to better understand the resulting geometry of fabricated traps, surface topology, and quantify additive concentrations in the gold layers. These results will be compared to the original mask design for a feedback loop leading to future generations of cavity ion traps. Final traps will be singulated and packaged onto an interposer that is attached to a ceramic pin grid array (CPGA) package. The die is precisely aligned and attached to the interposer with a high thermally and electrically conductive ultra-high vacuum (UHV) compatible epoxy. An automated wire bonder is used to repetitively make low profile wire bonds for optimum optical access to the surface of the chip.

Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND2015-10657A

1 C. L. Arrington, K. S. McKay, E. D. Baca, J. J. Coleman, Y. Colombe, P. Finnegan, D. A. Hite, A. E. Hollowell, R. Jordens, J. D. Jost, D. Leibfried, A. M. Rowen, U. Warring, M. Weides, A. C. Wilson, D. J. Wineland, and D. P. Pappas, 'Micro-Fabricated Stylus Ion Trap', Review of Scientific Instruments, 84 (2013).
A Photodetector Based on a Conjugated Polymer and PbS Colloidal Quantum Dots
Authors: Ghomian Taher , Choi Jin-Woo
Published: February 2020

This work presents the development of a light intensity sensor based using colloidal PbS quantum dots. A simple fabrication method at low cost makes the developed sensor suitable for light detection applications. Photodetectors based on quantum dots have various advantages compared to solid-state photodetectors. The reported advantages include ease of fabrication, narrow and tunable spectral response, large sensing area, reduced dark current, and high sensitivity [1, 2]. Solution-based fabrication makes the whole process simple and cost efficient.

The structure of the sensor in this work is shown in the figure having a light sensitive composite sandwiched by two electrodes of which one is usually a transparent electrode made of indium tin oxide (ITO). For validation, we employed PbS colloidal quantum dots and poly(2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene) or MEH-PPV to form the light sensitive composite [3]. In the light sensitive composite, a charge separation occurs by a photon generating a neutral exciton at the interface of the conjugated polymer and the quantum dots.

We started with an ITO coated glass substrate. The light sensitive composite made of MEH-PPV and colloidal quantum dots was then cast on top by spin coating. For the other electric contact, an aluminum layer was deposited by physical vapor deposition. The fabricated photodetector shows a promising sensitivity to incident light, and further characterization is currently underway. Since the entire structure of the photodetector is simple and the entire process can be done with low thermal budget, the photodetector can also be formed on a flexible substrate.

References

[1] P. V. Kamat, “Quantum dot solar cells. Semiconductor nanocrystals as light harvesters,” The Journal of Physical Chemistry C, vol. 112, pp. 18737-18753, 2008.

[2] I. Robel, V. Subramanian, M. Kuno, and P. V. Kamat, “Quantum dot solar cells. Harvesting light energy with CdSe nanocrystals molecularly linked to mesoscopic TiO2 films,” Journal of the American Chemical Society, vol. 128, pp. 2385-2393, 2006.

[3] S. A. Mcdonald, G. Konstantatos, S. Zhang, P. W. Cyr, E. J. Klem, L. Levina, and E. H. Sargent, “Solution-processed PbS quantum dot infrared photodetectors and photovoltaics,” Nature Materials, vol 4, pp.138-142, 2005.

Figure 1
Study of Alcohol Sensing Devices Using DMFC Technology
Authors: Soundrapandian Muthuraja , Chittur Krishnaswamy Subramaniam
Published: February 2020

Sensors for volatile organic compounds like alcohols (methanol and ethanol) can be fabricated using Direct Methanol Fuel Cell (DMFC) technology. The main problem is such a device is alcohol crossover. The alcohol diffuses from the anode through the electrolyte (perfluoro sulphonic acid membrane) to the cathode, where it reacts directly with the oxygen and produces no electrical current from the cell. This also results in poisoning of the cathode catalysts. The designed and fabrication of the sensor is by means of micro electro mechanical systems (MEMS) fabrication technology with the electrochemical inputs using a standard DMFC single cell arrangement. An ampherometric detection technique will be employed because of the redox reaction involved. The accuracy will be determined by the accurate detection of electric current or changes in electric current We have used a passive mode design protocol using COMSOL Multiphysics in the simulation. The design and simulation would involve optimization of various parameters, in the construction of the cell. We can optimize the overall power density and hence the sensitivity of the sensor by the modification of various parameters like the area of the working electrodes, separation distance and the electrode-electrolyte interface. A passive mode design protocol, for a cm cell area, using various parametric functions, and interfacing Darcy’s law of fluidic flow through a porous medium, under specific pressure and temperature, was applied. The designing involves the construction of gas diffusion layers using carbon matrix for electrodes with various parametric variations. Platinum and various alloy catalysts like Pt-Ru, Pt-Fe, Pt-Sn and Pt-Mo was chosen as the Oxygen Reduction Reaction (ORR) catalysts. The output of the cell was optimized for ampherometric detection. A MEMS based sensor with microfludic interconnects and its response characteristics will be presented.
Improvement of Hot Hole-Induced Degradation in HV Pmosfets
Authors: Lee Dongjun , Lee Changsub , Song Duheon , Choi Byoung-deog
Published: February 2020

We investigated hot hole-induced degradation in HV pMOSFETs. When the electric field between gate and channel is negatively higher than 6 MV/cm, an additional shift of sub-threshold swing leads to the shift of threshold voltage due to Fowler-Nordheim (FN) tunneling from the gate to the substrate. Hot hole is generated under highly-negative gate voltage near the surface, and accelerate the degradation. We observe that hot hole-induced degradation has a dependency of operation conditions and gate materials, and is suppressed under particular conditions. In this work, we studied the mechanism of hot hole-induced degradation qualitatively and discussed an improvement of this phenomenon by TCAD simulation and a variety of experimental results on the characteristics of electron and hole trap as function of gate materials.
Fabrication of an MWCNT-Reinforced Tin Anode for Use in Lithium Ion Batteries By Electrodeposition in Sulfuric Acid
Authors: Matsunaga Kouki , Shimizu Masahiro , Arai Susumu
Published: February 2020

Introduction

Lithium ion batteries employing graphite as the anode active material exhibit higher energy densities than conventional rechargeable batteries, although increasing the capacity of these devices will require the use of alternative anode compounds. Since tin (Sn) has a higher theoretical capacity (991 mAh g-1) than graphite (372 mAh g-1), it has been considered for this role. However, Sn tends to fall off the current collector during charge-discharge cycles due to significant volume variations, degrading the battery performance. One approach to avoiding this problem is to anchor the Sn layer to an underlying copper (Cu) layer using fibrous materials. We have already reported the excellent charge-discharge characteristics of a new tin anode reinforced with multiwalled carbon nanotubes (MWCNTs), formed by a combination of Cu/MWCNT composite plating and electroless tin plating.

In this study, we examined a new fabrication process for the MWCNT-reinforced tin anode structure based on tin electrodeposition using a sulfuric acid bath, and explored the correlation between the new negative electrode structure and its electrochemical characteristics.

Experimental

A Cu/MWCNT composite plating bath (0.85 M CuSO4
●5H2O + 0.55 M H2SO4 + MWCNT + polyacrylic acid), and a tin plating bath (0.2 M SnSO4 + 0.5 M H2SO4 + additive) were prepared. Using these baths, a Cu/MWCNT film was applied to a pure copper plate and tin was subsequently electrodeposited on the Cu/MWCNT film, resulting in the MWCNT-reinforced tin anode structure. For comparison purposes, tin was also electrodeposited on a pure copper plate. Electroplating was carried out under galvanostatic conditions at 25 °C.

The microstructure of the new tin anode was examined by field emission scanning electron microscopy (FE-SEM). The phase structure of the deposits was analyzed by X-ray diffraction (XRD).

Electrochemical studies of the tin-based anodes were carried out using coin cells (2032) assembled in an Ar-filled glove box. Each coin cell consisted of a lithium foil counter and reference electrodes and a tin-based anode as the working electrode. The electrolyte was 1 M LiPF6in a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) (1:1 vol%). Cycling tests were performed at a constant temperature of 25 °C.

Results and Discussion

Figure 1 shows a surface SEM image of the tin anode fabricated by the new process. MWCNTs are seen to be uniformly dispersed over the Sn layer. Figure 2 presents a cross-sectional SEM image of the tin anode. It can be seen that MWCNTs connect the Sn and Cu layers. No defects, such as voids or cracks, are observed between the two layers.

The electrochemical characteristics of the tin anode will be discussed in detail during the presentation.

References

1) S. Arai and R. Fukuoka, J. Appl. Electrochem., 46, 331 (2016).

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Fabrication and Characterization of Composite Membranes for Vanadium Redox Flow Batteries
Authors: Park Su Mi , Lee So Hee , Kim Haekyoung
Published: February 2020

Vanadium redox flow battery (VRFB) is a form of rechargeable battery which converts chemical energy directly to electrical energy. VRFB have been investigated for their potential utility as large energy storage systems due to their advantageous performances in terms of long cycle life, high energy efficiency, low cost, and flexible design. Catholyte and anolyte, in the negative and positive half-cells respectively, containing dissolved electro-active species flows through an electrochemical cell and generate cell potential. During operation of VRFB, ion-exchange membrane separate the catholyte and anolyte for preventing cross contamination which is induced by diffusion of different ions across from one half-cell to the other, will result in self-discharge and thus the loss of the chemical energy. Therefore, the ion-exchange is one of the most important components in the VRFB system and it should have low permeability and high ionic conductivity. A perfluorosulfonic acid (PSFA) membrane, such as Nafion (DuPont) for example, is the most commonly used membrane due to its high chemical-mechanical stability and high ionic conductivity. However, Nafion is permeable to electrolyte and expensive. The major focus is to modify the water-filled channels of the Nafion membrane by introducing non-conducting metal oxides. For example, SiO2 and TiO2 have been used to prepare Nafion-metal oxide composite membranes. The inorganic fillers, such as SiO2, act as a physical barrier for diffusing vanadium cation through the membrane channels, while allowing proton transport.

In this study, composite membranes based on Nafion and nanoclay were fabricated and characterized in terms of ionic conductivity and permeability. The ionic conductivity was measured with four point prove method and the permeability was measured with UV spectroscopy. For fabrication of the composite membranes, nanoclay solution was blended with Nafion solution according to the nanoclay composition in the dry membrane (5, 3 and 1 wt.% : identified as NF-NC 5, 3 or 1 wt.%, respectively). Ionic conductivity and the permeability were decreased with the increasing of the nanoclay composition in the composite membrane. With performances of VRFBs, the energy efficiencies of VRFBs and optimum composition of the composite membrane will be discussed.
Operando Observation of Cobalt Catalysts for Oxygen Evolution By Electrochemical XAFS Technique Using Soft X-Ray
Authors: Mitsutomi Yosuke , Yoshida Masaaki , Nagasaka Masanari , Yuzawa Hayato , Kosugi Nobuhiro , Kondoh Hiroshi
Published: February 2020

Photoelectrochemical water splitting using solar energy is an attractive candidate to produce hydrogen gas from water. This system consists of two half reactions of hydrogen and oxygen evolutions. Among them, the rate of oxygen evolution is generally slower than that of hydrogen evolution. Thus, the development of efficient oxygen evolution catalyst has been required toward highly active energy conversion system. Recently, a cobalt-borate electrodeposited from a dilute Co2+ solution in a borate-buffered electrolyte (Co-Bi) was reported to function as an efficient electrocatalyst for oxygen evolution reaction [1]. The structural information was investigated by X-ray pair distribution function (PDF), which indicates that Co-Bi catalyst is formed by coherent domains consisting of 3−4 nm cobaltate clusters with up to three layers [1]. However, the correlation between structure and activity is still unclear. Therefore, in this study, the Co-Bi catalyst was investigated by in-situ O K-edge XAFS measurements under potential control conditions.

Electrochemical XAFS measurements with transmission mode using soft X-rays were performed at BL3U in the UVSOR Synchrotron, according to the previous works [2]. A home-made electrochemical cell was used with Au/Cr/SiC thin film substrates as working electrodes, a Pt mesh counter electrode, and a Ag/AgCl (saturated KCl) reference electrode. Co-Bi catalyst was prepared on the Au/Cr/SiC working electrode at 1.0 V in 0.1 M potassium borate (K-Bi) electrolyte containing 0.5 mM Co(NO3)2.

Figure 1 shows the linear sweep voltammograms of bare and Co-Bi-modified Au electrodes in 0.1 M K-Bi electrolyte. The current density of oxygen evolution reaction for Co-Bi-modified electrode was higher than that for bare Au electrode, which exhibits that Co-Bi can function as an efficient oxygen evolution catalyst. Figure 2 shows the O K-edge XAFS spectra for Co-Bi catalyst at 0.9 and 0.0 V in 0.1 M K-Bi. Two absorption peaks assigned to the oxygen species in the CoOOH were observed around 530 and 531 eV. Meanwhile, an absorption peak of the lower energy was detected around 529 eV for the spectrum of Co-Bi at 0.9 V. Empirically, the O K-edge absorption peak position shifts to lower energies with increasing the formal oxidation state. Thus, the lowest energy absorption peak for Co-Bi sample at 0.9 V is probably attributed to Co4+ species, and the formation of the Co4+ is likely to contribute to oxygen evolution reaction. In this presentation, we will discuss more detailed assignment for the XAFS spectra and relationship with the activity of oxygen evolution reaction.

[1] D. G. Nocera et al., J. Am. Chem. Soc. 135 (2013) 6403.

[2] M. Nagasaka et al., J. Electron. Spectrosc. Relat. Phenom. 177 (2010) 130., J. Phys. Chem. C 117 (2013) 16343., Rev. Sci. Instrum. 85 (2014) 104105.

Figure 1
Analysis of Electrochemical Behavior of Carbon Nanomaterials Doped with Sulfur and Their Use As Support of Pt Nanoparticles
Authors: Montiel-Macias Elizabeth , Balbuena Perla B , Valenzuela-Muñiz Ana Maria , Verde Gómez Ysmael
Published: February 2020

The importance of finding new environmental friendly options for generation of energy, has taken more relevance in recent years. In this context, fuel cells have been recognized as a promising option to produce clean energy. The fuel cells have two main components: an electrolyte and two electrodes (an anode and a cathode), the latter usually is manufacturaded with precious metal supported on carbon (i. e. Pt/C), to its high electrocatalytic activity in the oxygen reduction reaction (ORR). However, the high cost of platinum, have pushed the research focus in alternatives to replace or decrease this material in the electrodes. Recent research works have shown that low platinum electrocatalyst supported on carbons doped with heteroatoms (e.g. B, N, P and S) have similar electrocatalytic activities to the conventional Pt/C for ORR. On the other hand, carbon nanotubes have unique properties that make them excellent candidates for using as electrocatalyst support. This work shows a sulfur-doped carbon nanomaterials synthesized by a modified chemical vapor deposition method. Toluene and thiophene were used as sources of carbon and sulfur, respectively. Ferrocene was used as a catalytic agent. Chemical reduction method was used to incorporate Pt nanoparticles to the doped materials. Physical and chemical characterization was performed by X-Ray Diffraction and Scanning Electron Microscopy, in order to determinate structural and morphological properties. The chemical elemental analysis was done by energy dispersive spectroscopy. The electrochemical performance of sulfur-doped carbon nanomaterials with and without nanoparticles of Pt was evaluated using cyclic voltammetry (CV) and rotating disk electrode (RDE) in acid media. Additionally, a preliminary modeling of the electrochemical behavior of doped materials obtained is presented. The model was performing using the Functional Theory Density (DFT) to explain the phenomena occurring during the ORR and the effect of modifying carbon structures with dopant S on this reaction.
Effect of Dispersion Methods on Oxygen Reduction and Ammonia Oxidation Reactions for Multiwall Carbon Nanotube Supported Pt
Authors: Harada Yuya , Ooya Kayato , Shirasaka Ryo , Shiroishi Hidenobu , Nishitani-Gamo Mikka , Nagai Keiji
Published: February 2020

When the activity of a catalyst was estimated by a rotating ring disk electrode (RRDE) method, the modified glassy carbon (GC) electrode was generally fabricated by casting catalyst suspension prepared by various methods, followed by drying under various conditions. There are many preparation methods for catalyst suspension. And it is known that the dispersivity of the catalyst on the GC electrode, which affects collection efficiency of H2O2as well as current density, depends on the above methods and conditions. Since an optimum method and condition often varies with the kinds of catalysts, researchers have to find them. However, it is difficult to evaluate the dispersivity on the electrode and reproducibility quantitatively. In this study, the dispersivity of multi wall carbon nanotube supported Pt catalyst (Pt/MWCNT) on the modified electrode prepared by various methods was estimated by digitizing height data of the electrode using a laser surface roughness meter.

30 wt% Pt/MWCNT (Pt particle size: 4.26 ± 0.09 nm) catalyst was synthesized by a microwave polyol process. 2 mg/mL of 30 wt% Pt/MWCNT-0.1 wt% various alcohol (MeOH, EtOH, and 2-PrOH) suspensions were prepared by ultrasonication for 10 min. 10 μL of the suspensions cast on a GC electrode, and the electrode allowed to dry by three method: 1) in air for 1 h (abbreviated as Air), 2) in saturated ethanol vapor pressure for 1 h (EV), and 3) in air with infrared irradiation for 10 min at 60 °C (IR). The samples were named as [solvent] – [drying method]. The modified electrodes were observed with a digital microscope (MSP-3080, PANRICO). And the surface height data of the modified electrodes were digitized with a laser surface roughness meter (SV-C4500 CNC, Mitutoyo), and the data were analyzed by a software "Roughness Analyzer" developed by our laboratory. The software detects secondary particles of the catalyst (clusters) on the electrode and the user can obtain the volumes, the average height, and the area of the clusters as well as the distribution of the catalysts from the center of the electrode.

Fig. 1 (a) shows cumulative cluster volume distribution for MeOH–Air, 2-PrOH-Air and EtOH–EV. The electrode surface prepared by the EtOH-EV method had the clusters up to 1.9×10-3
mm3, whereas those prepared by MeOH-Air and EtOH-EV had the clusters up to 6.7×10-4 mm3 and 1.9×10-3
mm3, respectively, suggesting that the EtOH-EV method tend to be aggregated to produce large secondary particles.

Fig. 1 (b) shows the average cluster heights of the samples. The standard deviation of the average cluster height for 2-PrOH-Air was the smallest of the three methods, indicating that the 2-PrOH-Air method is the most reproducible casting method of the three methods. Some quantification methods will be reported in the meeting.

Figure 1
Dynamic Transformations of Layered Compounds at Full Delithiation Due to Surface Triggered Reactions
Authors: Faenza Nicholas , Mukherjee Pinaki , Sallis Shawn , Pereira Nathalie , Das Hena , Ceder Gerbrand , Piper Louis F.J. , Cosandey Frederic , Amatucci Glenn G
Published: February 2020

Modern lithium-ion batteries using layered R-3m intercalation positive electrodes have insufficient practical capacity and energy density to meet the future demands of portable electronics, and electric vehicles. If the complete, reversible, theoretical capacity upon full delithiation of these materials could be accessed while retaining high voltages and a narrow voltage swing, a significant advancement in energy density could be achieved. Although, full delithiation of most layered compounds has been known for decades, the failure modes that prevent practical cycle life are still in question.

This paper focuses on a model R-3m layered compound of Li[Ni0.8Co0.15Al0.05]O2 (NCA) and explores the failure modes at the surface and subsurface utilizing a unique combination of operando microcalorimetry / electrochemical impedance spectroscopy , high resolution transmission electron microscopy, electron energy loss spectroscopy, x-ray photo electron microscopy, x-ray absorption spectroscopy, hard x-ray photoelectron spectroscopy, and x-ray diffraction. The development of operando microcalorimetry (isothermal and DSC mode) enables simultaneous measurement of the heat flux, current, and impedance, while controlling the environmental temperature and the electrochemical testing parameters. Although surface changes are known in NCA, we explore the evolution of the surface and subsurface at extreme levels of delithiation and take efforts to isolate the failure modes induced by cycling vs. static transitions. The progression of the surface and subsurface structure and chemistry is found to be much more complex than previously identified and has direct implications to impedance development throughout the electrochemical cell. Specific attention was given to surface catalyzed triggers of the surface and subsurface failure modes, evolution of surface and subsurface phase transformations, and comments on the broad applicability of our findings to other layered compounds.
Supercapacitors Using Binder-Free & Surfactant-Free CNT Electrodes
Authors: Brahim Sean , Indra Erik , Sy Ramon , Bonzato Paul , Maat Stefan
Published: February 2020

The rapidly increasing technological advances in society place more demands on efficient energy storage and the correspondingly important fast release of the stored energy. Supercapacitors are utilized where energy needs to be stored and released quickly, however they exhibit limitations to these demands that arise from various sources within the device such as the necessary incorporation of resistive additives to the electrode formulation. In the case of activated carbon (AC) electrodes, this constitutes the insulating binder, while for carbon nanotube (CNT) electrodes, the inclusion of appropriate surfactant is almost always necessary to promote stable dispersion for processing. This work discusses the use of surfactant-free and binder-free CNT electrodes for the fabrication of supercapacitor devices. The performance characteristics from pouch cells containing such CNT electrodes in organic electrolytes were benchmarked against commercial-grade AC supercapacitor devices on both cell volume and cell weight bases. EDLC performance advantages realized from eliminating the additives of surfactant and binder were significantly lower ac impedance at low temperature operation (80% reduction @ -30°C), higher capacitance retention after 100,000 cycles, and superior retention of capacitance at high temperature (95% of initial capacitance @ 70°C). The CNT-based supercapacitors of this work exhibited these performance advantages while still maintaining very competitive energy and power densities.
Metal-Free Nanocomposite Materials Based on Carbon Nitride Nanofibers and Graphene Oxide for Electrochemical Applications: Supercapacitors & Catalysts for Oxygen Reduction Reaction (ORR)
Authors: Movil-Cabrera Omar , Staser John A , Rodriguez-Silva Allen Armando
Published: February 2020

Electrochemical devices such as fuel cells and supercapacitors have recently been proposed as alternatives to remedy issues related to the scarcity of fossil fuels and climate change. However, it is necessary to reduce the costs and enhance the performance of these devices to compete economically with fossil fuel-based technology. This work is mainly focused on the development of new metal-free nanomaterials based on carbon nitride nanofibers (CNNF) and reduced graphene oxide (RGO) for the application mentioned above. More specifically, RGO sheets were decorated with CNNF in order to create 3-D porous materials with enhanced redox ability, charge transfer and chemical stability. RGO was obtained by the reduction of graphene oxide (GO) with hydrazine, whereas CNNF was obtained via polymerization of modified melamine. The fabricated materials were characterized via XRD, FTIR, UV-vis, TGA, XPS, SEM, TEM, cyclic voltammetry and galvanostatic charge/discharge. In addition, the effects of RGO/CNNF ratio and electrolyte nature on the electrochemical performance of these nanocomposite materials was evaluated.

 [Office1]Should this be “reduced”?
High Energy Hybrid Capacitor with Quinone-Grafted Negative Electrode in Neutral Aqueous Electrolyte
Authors: Babuchowska Paulina , Béguin François
Published: February 2020

It is known from literature that the capacitance performance of activated carbons (AC) can be enhanced by faradaic contributions owing to surface functionalities. Although many papers report on chemical oxidation of ACs to reach such objective, this method is not selective and leads to the formation of an important proportion of useless surface functional groups. Such disadvantage can be circumvented by using diazonium salts to graft molecules with the desired functionality on carbon, e.g., quinone-type. The redox activity of these molecules grafted on ACs has been demonstrated in sulfuric acid and potassium hydroxide aqueous media [1]. However, the materials display poor stability in KOH, and H2SO4 corrodes all non-noble metal current collectors used to build electrochemical capacitors (ECs). The objective of this presentation is to demonstrate the activity of anthraquinone-grafted carbons in non-corrosive aqueous media, such as neutral electrolytes [2], and to apply these materials as negative electrode in a hybrid capacitor where the positive electrode is from MnO2.

Anthraquinone (AQ) moieties were chemically grafted on the surface of the activated carbon DLC Supra 30 from Norit (Supra), giving the Supra-AQ carbon. The surface oxygenated functionality of as-received and grafted carbons was characterized by temperature-programmed desorption (TPD), using a TG equipment coupled with a mass spectrometer (MS). The larger mass loss for Supra-AQ (13.6 wt.%), compared to the pristine Supra one (2.6 wt.%), mainly related to CO evolution, confirms surface functionalization by quinone. The electrochemical response of Supra-AQ has been studied in 0.4 mol L−
1 phosphate buffer (pH=7.2) in order to avoid the shift of the redox peaks related with pH change during the measurements. In addition to the capacitive current related with the EDL formation, the CVs of Supra-AQ display reversible redox peaks characteristic of the grafted AQ molecules. As a result of grafting AQ, the capacity increases from 47 mAh g−
1 for Supra to 72 mAh g−
1 for Supra-AQ. During floating at 1.8 V, the hybrid Supra-AQ/MnO2 cell demonstrated stable capacitance and resistance, with 70% higher energy density than a Supra/MnO2asymmetric capacitor.

[1] G. Pognon, T. Brousse, L. Demarconnay, D. Bélanger, J.
Power Sources196 (2011) 4117.

[2] Q. Abbas, P. Ratajczak, P. Babuchowska, A. Le Comte, D. Bélanger, T. Brousse, F. Béguin, J. Electrochem. Soc. 162 (2015) A5148.
High-Performance Hybrid Supercapacitor with 3D Hierarchical Porous Flower-like Layered Double Hydroxide Grown on Nickel Foam As Binder-Free Electrode
Authors: Zhang Luojiang , Hui Kwan San , Hui Kwun Nam , Lee Haiwon
Published: February 2020

The synthesis of layered double hydroxide (LDH) as electroactive material has been well reported; however, fabricating an LDH electrode with excellent electrochemical performance at high current density remains a challenge. In this paper, we report a 3D hierarchical porous flower-like NiAl-LDH grown on nickel foam (NF) through a liquid-phase deposition method as a high-performance binder-free electrode for energy storage. With large ion-accessible surface area as well as efficient electron and ion transport pathways, the prepared LDH-NF electrode achieves high specific capacity (1250 C g-1 at 2 A g-1 and 401 C g-1 at 50 A g-1) after 5000 cycles of activation at 20 A g-1 and high cycling stability (76.7% retention after another 5000 cycles at 50 A g-1), which is higher than those of most previously reported NiAl-LDH-based materials. Moreover, a hybrid supercapacitor with LDH-NF as the positive electrode and porous graphene nanosheet coated on NF (GNS-NF) as the negative electrode, delivers high energy density (30.2 Wh kg-1 at a power density of 800 W kg-1) and long cycle life, which outperforms the other devices reported in the literature. This study shows that the prepared LDH-NF electrode offers great potential in energy storage device applications.

Figure 1
Interconnected Carbon Nanostructures for High Performance Supercapacitor Applications
Authors: Kim Hyun-Kyung , Kamali Ali Reza , Kumar R Vasant , Fray Derek John
Published: February 2020

Graphene has a two-dimensional honeycomb structure consisting of a single layer of carbon atoms with a sp2-bonding configuration and has recently attracted significant attention owing to its unique properties, which include an exceptionally high specific surface area and high electrical and thermal conductivities as well as mechanical and chemical stability. However, graphene sheets exhibit an extreme tendency to agglomerate or restack. This leads to a surface that is electrochemically less effective, low electrical conductivity, and an interlayer spacing that hinders access to electrolyte ions, thus limiting the use of the sheets in supercapacitor applications. Introducing carbonaceous materials such as metal oxide, carbon nanotubes (CNTs) between the graphene sheets is a viable strategy for preventing the sheets from agglomerating.

In this study, we report the scalable fabrication of a high-quality hierarchical interconnected carbon nanostructure, combining two-dimensional graphene nanosheets and one-dimensional graphene nanoscrolls from graphite by a simple hightemperature molten salt method. The electrode using the prepared material exhibited high reversible specific capacitance, excellent rate capability, and good cyclability because of their unique interconnected networks of carbon nanostructures with high electrochemically active surface area and high electrical conductivity. 

More details on the synthetic procedure, electrochemical and structural properties will be presented at the meeting.
Preparation and Electrochemical Properties of the Pouch-Type Edlc
Authors: Kim Ick-Jun , Yang Sunhye , Lim Sang-Min , Koo Bo-Kun
Published: February 2020

Long-term reliability and high power characteristic of the electric double layer capacitor (EDLC) is excellent but it is difficult to miniaturize due to the small energy density (about 5-6Wh / L). This low energy density makes it difficult to retrofit into a limited space in a car or transportation fields.

As a way to increase the energy density of the cylindrical EDLC in commercialization, some companies have developed a pouch type EDLC. The pouch type EDLC has an energy density of about twice the cylindrical EDLC, enabling the miniaturization of the module. However, the pouch-shaped EDLC is not a good long-term reliability due to the swelling phenomenon caused by the reaction between the electrolyte and the electrode.

In this study, as a way of solve the problem, we have investigated the effects of sheet-laminating electrode technology, positive/negative electrode mass ratio, electrolyte, assembly technologies and evaluation techniques on the electrochemical properties of the pouch type EDLC.
Cycling Performance of Ppy Derived Carbon Based Symmetric Supercapacitors in Aqueous Electrolyte
Authors: Bello Abdulhakeem , Barzegar Farshad , Madito Moshawe Jack , Momodu Damilola Yusuf , Khaleed Abubakar Abubakar , Masikhwa Tshifhiwa Moureen , Dangbegnon Julien Koudio , Manyala Ncholu
Published: February 2020

Electrochemical capacitors (ECs) also known as supercapacitors have attracted significant interest for the development of next generation of energy storage systems. ECs are characterized by their high power density and low energy density when compared with batteries [1,2]. ECs are suitable for transient energy saving application such as energy capture during braking in vehicles, in construction equipment such as cranes and for opening of doors in the A380 Jumbo jet, portable and flexible electronics [1]. However, the performance of ECs devices for most of these applications is exclusively dependent on the physicochemical properties of the electrode materials. Electrode materials with diverse dimensionalities such as 1D, 2D and 3D nanostructures have been explored to improve supercapacitive properties by taking advantages of the unique ability of the different nanostructure for ion propagation and charge storage [3,4]. The stability of supercapacitors is a very important feature for characterization of ECs devices. The traditional method of evaluating the stability is via the constant current charge-discharge (CCCD) cycling over several thousands of cycles which in many cases does not show degradation to the ECs devices. As an alternative to this, voltage holding or floating test has been proposed as a reliable technique to test the stability of electrode materials [5,6]. Here we report on the performance (speciﬁc capacitance) of symmetric capacitors based on mesoporous PPY derived carbons and the stability of the symmetric capacitors based on voltage holding (floating conditions) operating in aqueous electrolytes evaluated by cyclic constant current charge-discharge tests. Variation in the speciﬁc capacitance values with the floating conditions shows a good cycling life performance in alkaline electrolyte for ~190 h with slight degradation observed after 140 h.

References

[1] Simon P, Gogotsi Y. Materials for electrochemical capacitors. Nat Mater 2008;7:845–54.

[2] Conway BE. Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications. Kluwer Academic/Plenum: New York; 1999.

[3] Simon P, Gogotsi Y. Capacitive energy storage in nanostructured carbon--electrolyte systems. Acc Chem Res 2012;46:1094–103.

[4] Yan J, Wang Q, Wei T, Fan ZJ. Recent Advances in Design and Fabrication of Electrochemical Supercapacitors with High Energy Densities. Adv Energy Mater 2014;4:43.

[5] Weingarth D, Noh H, Foelske-Schmitz A, Wokaun A, Kötz R. A reliable determination method of stability limits for electrochemical double layer capacitors. Electrochim Acta 2013;103:119–24.

[6] Weingarth D, Foelske-Schmitz A., Kötz R. Cycle versus voltage hold - Which is the better stability test for electrochemical double layer capacitors? J Power Sources 2013;225:84–8.
Reactor R&D: Effect of Plasma Additives on Endohedral Metallofullerene and Empty-Cage Fullerenes
Authors: Stevenson Steven , Budd Sarah K , Kime Brittany L
Published: February 2020

Metallofullerenes encapsulating metallic nitride clusters represent exciting molecules for fundamental study and application development.  Mixed-metal nitride clusters are also of interest due to their dissimilar metals.  The first step in providing these endohedrals to the scientific community is their synthesis, such as in an electric-arc reactor.   Our hypothesis is that we can tune the fullerene product distribution in soot by varying the chemicals that we add to cored graphite rods.  In this presentation, our results will demonstrate that plasma additives do permit us to selectively make different types of fullerenes.