bluuebunny/crossref_metadata_2025 huggingface dataset:
(Keynote) Biomimetic Preservation of Protein and Cell Surface Markers with Metal-Organic Frameworks for Controlled Protein Delivery and Room Temperature Storage and Shipping
Authors: Gassensmith Jeremiah J
Published: December 2020

Biological specimines from histology, protein-based therapeutics, and many biomacromolecules are unstable at room temperature. This instability necessitates considerable infrastructure be in place to allow the spoilage-free transportation of a number of important medicines including vaccines, insulin, antibody-based therapeutics, etc. This cold-chain infrastructure can increase the cost of these drugs by as much as 80%. Further to these problems, the instability of protein-based materials time-delayed or slow release formulations difficult. I will present a general method to "biomimetically" encarceate biomacromolecular assemblies into crystalline thermodynamically stable crystalline frameworks that readily dissolve in vivo to release intact and natively folded proteins. I will discuss strategies to incorporate these into prosthetics and implants for long-term delivery with a focus toward methodology in improving patient compliance with drugs and patient outcomes following prosthetic implants.
Welcome Remarks - H05: Metal Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) and Porous Hybrid Materials: Characterization, Technology, Bio-Applications, and Emerging Devices 2
Authors: Redel Engelbert
Published: December 2020

Welcome to H05: Metal Organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) and Porous Hybrid Materials: Characterization, Technology, Bio-Applications, and Emerging Devices 2! Take a moment to listen to welcome remarks from the lead organizer, Engelbert Redel.
Fabrication of Amorphous SRVOX-Based Memristor for Neuromorphic Computing
Authors: Lee Tae-Ju , Kim Su-Kyung , Seong Tae-Yeon
Published: December 2020

Because resistive random access memory (RRAM) has advantages, such as fast switching speed, low energy consumption, and simple device structure, it is promising device architecture for memory, artificial intelligence, and neuromorphic computing. In particular, for RRAM for use in neuromorphic applications, it must be able to mimic synaptic behavior by pulse modulation. In order to have such a characteristic, the resistance state has to be gradually changed by the stress, e.g., potentiation and depression. High linearity is required because the linearity of RRAM obtained through each resistance state is evaluated as an especially important property for artificial synaptic applications.

In this work, we performed the electrical properties of sputter-deposited amorphous strontium vanadate (a-SVO) RRAM with Pt bottom electrode and Ag top electrode. Sufficient reproducibility and uniformity between devices was realized. The highest resistance ratio of ~ 103 was observed and insignificantly changed for retention testing up to 2 × 104 s. In particular, the conduction filament generated from the a-SVO RRAM was adjusted according to the regulation of voltage stress to obtain a multi-level resistance state. It was confirmed by ToF-SIMS analysis and COMSOL Multiphysics simulation that the conduction filament was formed by Ag atoms. Hopfield Neural Network simulation was conducted to verify that the performance of analog resistive switching behavior of a-SVO RRAM is suitable for neuromorphic computing. The accuracy of our simulated device was saturated to 86.8 % for 100,000 asynchronous iterations. The results imply that our a-SVO RRAM is of great potential for use in neuromorphic computing.
Electrochemical Manipulation of the Electron Transports of SrCoO
x
Epitaxial Films
Authors: Yang Qian , Cho Hai Jun , Jeen Hyoungjeen , Ohta Hiromichi
Published: December 2020

Strontium cobaltite (SrCoO
x
) has attracted increasing attention as the active material for novel electrochemical memory devices [1-3] because its optical, electrical, and magnetic properties can be controlled electrochemically. Especially, the redox reaction between SrCoO2.5 and SrCoO3 is important because one can control from antiferromagnetic insulator to ferromagnetic metal. In order to utilize this redox reaction as a practical memory device, the macroscopic phenomenon must be clarified. Here, thermopower analysis is used to clarify the electrochemical oxidation macroscopically. A 6-nm-thick GDC (10 mol% Gd-doped CeO2) film was heteroepitaxially grown on (001) YSZ substrate followed by the growth of ~40-nm-thick SrCoO2.5 by pulsed laser deposition. The out-of-plane XRD patterns of the resultant films showed that the SrCoO2.5 were heteroepitaxially grown on the GDC/YSZ with the epitaxial relationship of (001) [100] SrCoO2.5 || (001) [110] GDC/YSZ. We then deposited Pt electrode on the backside of the YSZ substrate and applied current into the film as schematically shown in Fig. a with -5 or -10 V at 300 °C in air. In order to measure the electron transports of the intermediate state, we suspended the electrochemical oxidation several times. From the XRD analyses of the films, we clarified that the conversion rate from SrCoO2.5 brownmillerite to SrCoO3 perovskite could be controlled electrochemically. Although the resistivity (Fig. b) of SrCoO2.5 film was high (5.5 Ω cm), the resistivity dropped after slight oxidation due to the parallel electronic circuit composed of very low resistive SrCoO3 (0.35 mΩ cm). Furthermore, the thermopower (Fig. c) dropped from 70 μV K-1 to ~0 μV K-1 after slight oxidation. A steep decrease in both resistivity and the absolute value of thermopower of electrochemically oxidized SrCoO
x
epitaxial films indicates the columnar oxidation firstly occurred along the oxidation direction and then spread perpendicular to the oxidation direction. This macroscopic image of the electrochemical oxidation would be useful for developing a functional device utilizing the electrochemical redox reaction of SrCoO
x
.

[1] N. Lu et al., Nature
546, 124 (2017).

[2] T. Katase et al., Adv. Electron. Mater. 2, 1600044 (2016).

[3] Q. Lu et al., Nano Lett.
16, 1186 (2016).

[4] Q. Yang et al., Adv. Mater. Interfaces
6, 1901260 (2019).

Figure 1
Development of Electrochromic Device with Poly(3,4-ethylenedioxythiophene) on Invisible Silver-Grid Transparent Electrode
Authors: Kawabuchi Miyuki , Tsuneyasu Shota , Hashimoto Natsuki , Ohsawa Masato , Satoh Toshifumi
Published: December 2020

Electrochromic (EC) reaction is defined as a reversible color change which induced by the electrochemical redox reactions. The EC device is promising as an optical modulation device such as a display and a window. However, a flexibilities of the EC device is unsatisfied because conventional EC device consists of transparent conductive oxide on the glass substrate. To overcome this, we have developed a gravure offset printed invisible Ag-grid transparent electrodes by using Ag-nanoparticles ink,[1] and demonstrated that a powder electroluminescent device by this transparent electrode showed the high bending stability.[2], [3] Therefore, it is also expected the realization of EC device showing high bending durability.

In this study, the novel EC device composed of poly(3,4-ethyenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) has been fabricated on a gravure offset printed fine Ag-grid transparent electrode and evaluated optical and electrochemical properties. Scanning the potential from 0 V (vs. Ag/Ag+) to the negative direction, the cathodic current due to the reductive reaction of PEDOT:PSS was observed, and the absorbance correspond to the coloration of PEDOT:PSS was increased. Then, when scanning the potential to the positive direction, the anodic current due to the oxidative reaction of PEDOT:PSS was observed, and the absorbance was decreased. This changing in the absorbance were observed several tens of times. These evaluation results demonstrate that PEDOT:PSS develops a reversible color change with the EC reaction on the fine silver-grid transparent electrode.

Reference

[1] M. Ohsawa, N. Hashimoto, Mater. Res. Express, 5, 085030 (2018).

[2] N. Takeda, S. Tsuneyasu, K. Yanagawa, N. Hashimoto, M. Ohsawa, T. Satoh, Electron. Lett., in press.

[3] M. Ohsawa, N. Hashimoto, N. Takeda, S. Tsuneyasu, T. Satoh, Flex. Print. Electron. (under review).

Figure 1
Effect of Specific Surface Area of Counter Electrode in Hybrid Capacitor Type Electrochromic Device
Authors: Liang Zhuang , Nakamura Kazuki , Kobayashi Norihisa
Published: December 2020

We have already reported a novel hybrid capacitor multicolor electrochromism (EC) in a single device by introducing a porous capacitive counter electrode, ITO particle-modified electrode.1 Due to the formation of the electrical double layer on the counter electrode successfully compensated the charge consumption of EC reaction enables certain colors to be represented selectively both anodic and cathodic EC molecules by just using two electrodes and sandwiched electrolyte. In our another paper, we also found that the capacitance has a greater impact on the appearance of multiple colors.2 Beyond those, in practical EC applications, the performance of coloration, response time also play very important roles. In this regard, the effect of the increase of specific surface area of counter electrode on the EC properties of the hybrid capacitor ECD has not been studied in detail.

In this paper, we fabricated several ECDs having hybrid capacitor structure with flat ITO electrode as the working side and ITO particle-modified electrodes which having different thickness (aim to increase the specific surface area) as the counter side. As the EC molecule, we employed the molecule of 10-methylphenothiazine (MPT). We discussed the effect of increased specific surface area of the counter electrode on the EC properties in the hybrid capacitor ECD.

We measured the capacitance of the ITO particle-modified electrodes having different thickness. Fig. 1 shows the relationship between electrostatic capacitance and thickness of ITO particle-modified electrodes. From the result, we can clearly know that with the increase of thickness, the capacitance showed an increasing trend.

Fig. 2 shows the transmission spectra of the ECDs under application of positive voltage of 1.2 V for 10 s. The transmittance of ECDs decreased strongly due to oxidized MPT molecule appeared at around 515 nm. As the result, color of ECDs changed from transparent state to pink color. At the same driving condition, with the increase of thickness, the amount of charge consumed by EC reaction increased, leading to more obvious ΔT. This result can be explained that with the larger capacitance due to increased specific surface area leading to larger accumulation of electrical charge on the counter electrode, oxidative reaction of the MPT was promoted on the working electrode, toward increased density of pink color.

References

[1] Z. Liang, M. Yukikawa, K. Nakamura, N. Kobayashi, Phys. Chem. Chem. Phys., 2018, 20, 19892–19899.

[2] Z. Liang, K. Nakamura, N. Kobayashi, Sol. Energy Mater. Sol. Cells, 2019, 200, 109914-109921.

Figure 1
Fast Switching of Photoelectrochromic Device Using Ligand Attached TiO2 Layer
Authors: Sarwar Saad , Hong Sungjun , Han Chi-Hwan
Published: December 2020

We fabricated a scalable and economical photoelectrochromic smart window that can be darkened under illumination and bleach in dark conditions. The materials used in this device can cut the cost by omitting transparent conducting oxide and ruthenium dye. The device is composed of a screen-printed WO3 layer on the soda-lime glass, a screen-printed TiO2 layer that is modified by attaching a ligand (5-methyl salicylic acid), a redox mediator and a soda-lime cover glass. The performance of the different types of salicylic acid ligands is investigated first in the dye-sensitized solar cells. The best performing ligand (5-methyl salicylic acid) was then used in the photoelectrochromic device. Using soda-lime glass and 5-methyl salicylic acid instead to conducting glass and ruthenium dye results in higher stability with additional benfit of low cost. The change in transmittance of the device also depends upon the thickness of WO3 and TiO2 layers and the optimized thickness was used in the device. The device showed fast coloring with a change in transmittance of 40% at 550nm within 3 minutes. However, the device showed slow bleaching and took 3 hours to bleach partially and 24 hours to bleach fully. To address the issue of slow bleaching, platinum particles were added in the WO3 and TiO2 layers to speed up the back reaction. The Pt particles used as a catalyst showed a dramatic improvement in the bleaching speed of photoelectrochromic device without affecting the coloring performance of the device. The device bleached fully within 30 minutes in the dark when Pt was incorporated in the WO3 layer.
Microscopy Studies of the Catalyst Inks for PEM Fuel Cells
Authors: Pedram Sara , Macauley Natalia , Zhong Sichen , Xu Hui , Jankovic Jasna
Published: December 2020

The microstructure of the catalyst layer in proton exchange membrane fuel cell (PEMFC) is one of the key factors that may determine fuel cell performance. The ink preparation, including dispersion solvent, mixing time, and mixing power, is among the less studied parameters that would influence the ionomer distribution on the catalyst surface and the continuity of the carbon network. In this work, novel characterization approaches have been used to investigate the effect of the Pt/C catalyst ink preparation conditions on the morphology and structures of the catalyst layer. Microscopy analysis revealed that longer mixing time led to better electrode structures than shorter mixing time. The longer mixing time enabled superior continuity of the ionomer network and high porosity in the cathode layer that contributes to improved proton conductivity and mass transport. This has been reflected in performance and durability tests, where the electrode made from 5-day catalyst ink displayed improved performance compared to the one from 3-day ink. Durability studies showed 26% and 43% loss of initial mass activity for 5 days and 3 days mixing, respectively. In addition, the catalyst layer prepared with ethylene glycol as the dispersion solvent showed better durability than water/1-propanol based solution. The effect of the ink mixing power as another considerable factor on the resulting catalyst layer morphology will be investigated. This work will provide an insight into the better electrode design to maximize the performance of PEM fuel cells.
Microporous Layer Water Saturation Determination By Sub-Voxel X-Ray Computed Tomography
Authors: Chen Yen-Chun , Liu Wenmei , Berger Anne , De Angelis Salvatore , Schmidt Thomas J. , Buechi Felix N.
Published: December 2020

A microporous layer (MPL) is typically added to gas diffusion layers in polymer electrolyte fuel cells (PEFC) to enhance fuel cell performance and water management. The related transport mechanisms are not completely understood and therefore characterization is required. However accurate determination of MPL liquid water saturation has not yet been broadly addressed, except for preliminary work.

We demonstrate that X-ray computed tomography (XCT) is suitable and efficient in characterizing MPL’s local liquid water saturation in an ex situ model experiment setup. Our image evaluation pipeline was first developed on porous polymeric membrane materials, validated by independent gravimetric measurements. Mercury intrusion porosimetry (MIP) on MPL further justifies the efficacy of the method. The pipeline has indicated an accuracy of ca. ±7% and a field of view of 6 mm, which suits differential cell investigations. The linear relationship of greyscale value (GSV) and linear attenuation coefficients is shown to hold even for a polychromatic radiation source. This methodology has the potential to accurately characterize the water saturation in MPLs under operando PEFC conditions.
Mapping of Heterogeneous Catalyst Degradation in Polymer Electrolyte Fuel Cells
Authors: Cheng Lei , Khedekar Kaustubh , Rezaei Talarposhti Morteza , Perego Andrea , Metzger Michael , Kuppan Saravanan , Stewart Sarah , Atanassov Plamen , Tamura Nobumichi , Craig Nathan , Zenyuk Iryna V. , Johnston Christina
Published: December 2020

Durability of cathode catalyst in polymer electrolyte fuel cells (PEFCs) is a key factor, limiting large-scale commercialization of PEFC for transportation applications. The catalyst degradation occurs during operational load profiles switches from ideal to peak, where multiple operational factors affect the degradation rate. The catalyst degrades heterogeneously as the catalyst particles are exposed to local variations throughout the entire catalyst layer during operation. State-of-the-art analytical techniques for studying degradation of Pt catalyst do not possess fine spatial resolution to elucidate such non-uniform degradation behavior at a large electrode level.

We report a new methodology to spatially resolve and quantify the heterogeneous Pt catalyst degradation over a large area (several cm2) of aged MEAs based on synchrotron X-ray micro-diffraction. PEFC samples were aged using voltage cycling as an accelerated stress test. The heterogeneity of catalyst degradation at a micrometer length scale was visualized by mapping Pt catalyst particle size after voltage cycling between 0.6V and open circuit potential. We demonstrated in details that the Pt catalyst particle size growth was non-uniform and followed the flow field geometry. The Pt particle size growth was greater in the area under the flow field land, while it was minimal in the area under the flow field channel. Additional non-uniformity was observed with the Pt particle size increasing more rapidly at the gas outlet area of than the Pt particle size at the inlet area.

Figure 1
Technical and Economic Analysis of Pemfcs and DMFCs for Material Handling Applications
Authors: Metzger Nathaniel , Li Xianglin
Published: December 2020

There has been tremendous growth in the material handling industry partially driven by the fast-growing logistics industry. As the major transport equipment, forklift trucks powered by internal combustion engine and petroleum-driven fuels such as gasoline, diesel, or liquefied petroleum gas (propane) historically dominate the forklift industry. Within the 850,000 total forklifts in use across the United States, there are only more than 20,000 forklifts driven by fuel cells. Based on available forklift deployment data between 2004 and 2014, it is estimated that only about 6% of fuel-cell forklifts are driven by DMFC. DMFC-driven forklifts have huge growth potentials due to its low infrastructure cost, low fuel cost, and easy handling of liquid methanol. As a result, the research team will analyze the technical and economic feasibility of DMFCs as the next generation power source for the material handling industry.

Preliminary analyses have compared the life cycle cost (LCC) of PEMFC forklifts and DMFC forklifts. The analyses include the cost of fuel cell components, balance of plant (BOP), system assembly, fuel cost, performance of the fuel cell, as well as the average operating conditions of Class I, II, and III forklifts. If the hydrogen price is assumed to be $8/kg, the min LCC ($36,682) of the PEM fuel cell is reached at a moderate current density (533 mA/cm2). Due to the high price of hydrogen, the fuel cost over the lifetime ($26,415 or 72%) is counted for the majority of LCC while the cost of infrastructure and fuel cell installation ($10,267 or 28%) makes up the rest of LCC. The LCC of PEM fuel cell is very sensitive to the hydrogen price. When the hydrogen price varies between $4/kg and $12/kg, the LCC changes between $23,079 and $49,691.

The min LCC ($43,308) of the DMFC is reached at a similar current density (591 mA/cm2). Even though DMFC has much lower efficiency (27%) at the min LCC than PEM fuel cell (60%), the fuel cost of DMFC over lifetime ($17,273) is lower than that of the PEM fuel cell because hydrogen price is at least an order of magnitude higher than methanol price per heating value. Since DMFC uses much more PGM catalyst than PEM fuel cell to generate the same amount of power, DMFC’s installation cost accounts for the majority (60%) of DMFC’s LCC. Comparisons between the LCCs of DMFC and PEMFC indicate that DMFC could be a more economic feasible technology than PEMFC for Class I and II forklifts in relatively small warehouses with less than a dozen forklifts and/or if the hydrogen price is high (>$10/kg).
Analysis of Optimized Performance Design for Non-latch Locked Flexible Fuel Cell
Authors: Kuo Chun-Hsien
Published: December 2020

When the volume of a product decreases and the need of power supply remains, the problem of lacking of space for power equipment appears. In this condition, flat planar fuel cells could be one of the solutions for this challenge; additionally, flat planar flexible fuel cells with non-latch locks can be applied to products with curvy surface in order to fit with their aesthetic design. This research analyzes the parameters of fuel cell bending deformation to find the best combination. The Taguchi method is applied to optimize the following parameters: bending direction, width of pressing bead, pressing force, curvature depth, bending times, opening rate of cathode air-intake holes, as well as elongation. The test results indicate the highest contribution rate with the bending depth, followed by the bead area, and the third one is the circular cathode air-intake holes. All of the above parameters have contribution rates over 10%. Moreover, the 15% elongation of cathode, arranged with larger curvature depth and smaller width of pressing bead, concentrates the force within specific portion and makes the internal resistance smaller. The overall performance of the fuel cell is thus improved. Fuel cell components in this research are laminated with glue, instead of screw locking, in order to better prevent gas leakage and to have better anti-vibration ability. The fuel cell can even be formed into U-shape to fit the curvy surface of different products. The fuel cell’s power density acquired from the optimized parameters by the Taguchi method is 82.5mW/cm^2. This is also the optimized power density for the fuel cell.
Investigation of Borohydride/Peroxide Desalination Cell in a Batch Regime
Authors: Hamilton Shawn Nicholas , Bassi Amarjeet Singh , Karamanev Dimitre
Published: December 2020

For this study, a batch lab-scale electrochemical desalination cell (EDC) was constructed to remove dissolved salts from water by utilizing the redox chemical reactions between sodium borohydride and hydrogen peroxide. The 3-compartment (NaBH4/NaCl/H2O2) EDC cell was effective in desalinating solutions containing different salts: NaCl, CaCl2, MgCl2 and KCl. Combinations of different anion exchange membranes with different cation exchange membranes were studied in order to improve the performance of the EDC. In addition, we found a decrease of 85% – 99% of the salinity in the batch regime for the different salts. The EDC’s maximum current and power densities were 5.32 A/m2 and 2.75 W/m2 at 25 °C, respectively. Also, in a closed cell, the maximum current and power densities were 6.10 A/m2 and 4.4 W/m2, respectivelyat 80 °C. These results demonstrated the successful desalination operation of an EDC using NaBH4 and H2O2 in the batch regime.
Comparison of Planar and Tubular Flow Field Plates for Proton Exchange Membrane Fuel Cells (PEMFCs) through Simulation
Authors: Tang Aubrey , Jankovic Jasna , Crisci Louis , Pedram Sara
Published: December 2020

The proton exchange membrane fuel cell (PEMFC) is an excellent clean energy alternative to current non-renewable energy sources. Bipolar plates (BPPs) are a key component of these PEMFCs and are directly responsible for their performance. Much research has been invested in channel design, materials characterization, and interfacial phenomenon of BPPs but not much attention has been paid to the architecture of the plate itself. Traditional BPPs are created in a planar form, but recent research efforts have revealed a novel tubular design that performs equally as well if not better than conventional plates. This study will experiment with three different channel designs for both planar and tubular plate configurations. The finite element ANSYS software will be used to determine and visualize velocity and pressure distributions of fluid flow through the BPP channels. Results from this study will validate whether the tubular configuration is superior to the planar form as well as which channel design is most appropriate for either configuration.
Effect of Pt Solution Concentration during Direct Preparation of Core–Shell Pt Cathode in MEA Catalyst Layer for PEFC
Authors: Fukunaga Hiroshi , Tsuji Masayasu , Ito Yu , Takimoto Daisuke , Sugimoto Wataru
Published: December 2020

Core-shell catalyst, which consists of thin Pt shell on non-Pt metal core, has been attracting attention as a low-Pt catalyst for polymer electrolyte fuel cell (PEFC). Typically, it is synthesized by using Cu-underpotential deposition (Cu-UPD) followed by surface limited redox replacement (SLRR). However, since this method is normally performed on a rotating disk electrode, it can only be prepared on a microgram scale. We have been developing a novel method to overcome this problem by directly performing Cu-UPD and SLRR to the catalyst layer made from the core material. Using this method, the reaction area is increased since the reaction occurs on particles in the three-dimensional network. In our previous study, we have reported that a Pd@Pt/C catalyst layer prepared by this method shows higher mass activity than conventional Pt/C. However, deposition at the surface of the catalyst layer appeared to be larger than in the interior of the layer. In this study, the effect of Pt ion solution concentration on the Pt deposition behavior was studied to develop highly active low-Pt catalyst layer by this novel method.

Pd/C was used to fabricate a catalyst layer made of core material. Cu-UPD and SLRR was performed twice on this catalyst layer. In the SLRR process, Pt ion solution with various concentration was used. When a high concentration solution was used, large deposition at the surface was apparent. On the other hand, when a low concentration solution was used, the deposition at the surface was suppressed but the amount of Pt deposition was insufficient. By using both the low and high concentration solution, metallic luster caused by the large depositon of Pt was not observed, and a sufficient amount of Pt was deposited. The performance of a MEA prepared by this catalyst layer showed higher performance than that prepared by the previously reported method.
Characterization of Sulfonylated Poly(styrene) Based Proton Exchange Membranes for Fuel Cells
Authors: Dueerkop Dennis , Zalewski Laura , Schmiemann Achim
Published: December 2020

The change from an energy industry based on fossil fuels to an energy industry based on renewable energy sources is a global challenge. For this reason, dynamic storage systems are needed to be developed for fluctuating wind and solar energy. Water electrolysis and fuel cells are important energy converters that offer the possibility of using hydrogen as an energy carrier. Generally, good thermal-oxidative stability and high proton conductivity are expected for membranes in fuel cells [1].

As an alternative to perfluorosulfonic acid based membranes, hydro-carbon based proton exchange membranes may reduce stack costs. This assumption motivates us to synthesize and investigate polymer membranes whose proton conductor is cross-linked sulfonated sulfonylated poly(styrene) (ssPS). The advantage of ssPS in contrast to sulfonated polystyrene is the stability of the sulfonic acid group at temperatures around 100°C [2]. Disadvantages of ssPS are the water solubility at high degrees of sulfonation (ion exchange capacity of about 3,5 mmol/g) and poor film formation properties.

According to this, the proton conductor must be cross-linked during synthesis and embedded in a nonpolar polymer matrix during the membrane production.

Our investigations show that ssPS (non-cross-linked) has a similar thermal-oxidative stability as Nafion® (examined by thermal analysis/oxidative induced temperature (OIT)) [3]. The cross-linking of ssPS with divinylbenzene mixtures leads to a less good thermal-oxidative stability. Furthermore, our results show that the water uptake can be adjusted by varying the amount of cross-linker. In addition, the proton exchange membranes show conductivities in the range of Nafion® 117 at room temperature.

The presentation will show the development of a new proton exchange membrane and its characterization. To discuss the membranes quality, the focus is on ion exchange capacity (stability at 90°C), thermal-oxidative stability (differential scanning calorimetry), water uptake and electrical resistance as a function of temperature up to 90°C.

This work is supported by the Federal Ministry of Education and Research (BMBF).

[1] J.A.Kerres, A.Katzfuß, A.Chromik, V.Atanasov, J. Appl. Polym. Sci. 2014 , 131 , 39889.

[2] H.Widdecke, M.Dettmer, W.Reith, Patent DE4425216C2, 2003.

[3] G.W.Ehrenstein, G.Riedel, P.Trawiel, Thermal analysis of plastics, Hanser Verlag, 2004.
Synthetic Approach to Hydrocarbon Proton Exchange Membranes Using Anion Exchange Membrane Precursors
Authors: Pagels Michael , Adhikari Santosh , Walgama Ramali , Singh Asheesh , Han Junyoung , Shin Dongwin , Bae Chulsung
Published: December 2020

Proton exchange membranes (PEMs) are a crucial component to many electrochemical energy conversion devices, including low temperature hydrogen fuel cells and water electrolyzers. Perfluorosulfonic acid-based PEMs have overwhelmingly been the material of choice for these applications however, they are not ideal due to high cost, low glass transition temperature, and lack of synthetic diversity leading to unoptimized material performance. Hydrocarbon PEMs on the other hand have been explored as alternatives to perfluorosulfonic acid materials, although in general have lower proton conductivity, excessive water sorption and poor oxidative stability. Despite a large body of works focusing on hydrocarbon PEMs, most are based on aryl ether containing polymers such as poly(aryl ether sulfone). Recently, the PEM research community has shown that wholly aromatic polymer systems exhibit improved oxidative stability and restrict water uptake, allowing for higher ion exchange capacities. The synthetic routes of these polymer systems, however, are limited to sulfonation of aromatic unit through hash sulfonating conditions leading to ill-defined polymers or through complicated multistep synthetics routes, often requiring transition metal catalysts. Herein, we report widely applicable synthetic methods and exceptional properties of hydrocarbon based PEMs without any aryl ether linkages. To achieve this PEMs were synthesized from materials bearing a haloalkyl side chains. Since, anion exchange membranes (AEM) are commonly synthesized from haloalkyl bearing polymers and the polymer property requirements of PEMs and AEMs are similar, (i.e. no aryl ether linkages, high IEC, dimensional stability, ect.) this ushers in a new generation of stable hydrocarbon PEM materials from the vast library of stable AEMs. Furthermore, the synthetic procedures are based on simple SN2 and oxidation chemistry requiring no metal catalysts or harsh reaction condition. The resulting polymers show excellent conductivity and restricted water uptake at higher temperatures due to improved phase separation stemming from the attaching sulfonate group to a tethered side chain of polymer. Additionally, in highly oxidative Fenton’s reagent test, no discernable changes to the polymer performance of structure was observed.
The Effect of Backbone Structure on Functional Properties in Anion Exchange Membranes; Comparison of Poly(fluorene) with Poly(biphenylene) and Poly(terphenylene)s
Authors: Walgama Ramali , Jeon Jong Yeob , Maurya Sandip , Kim Yu Seung , Bae Chulsung
Published: December 2020

The irreversible environmental impacts caused by energy generation from fossil fuels calls for a paradigm shift in the energy conversion and storage. Among many alternative energy technologies hydrogen based electrochemical devices gain significance because of its high efficiency and environmentally benign byproduct formation. Ion exchange polymers play a key role in electrochemical devices as solid-state electrolytes conducting ions between the electrodes while acting as a physical barrier to reactants and electrons. Electrochemical reactions carried out under high pH medium in fuel cells and electrolyzers using anion exchange membranes (AEMs) have gained significant traction recently, due to the prospect of using non-platinum group metal electrocatalyst for the redox reactions. While AEMs remain a crucial part of electrochemical devices such as alkaline exchange membrane fuel cells and alkaline electrolyzers, the absence of a suitable membrane is an impediment for the widespread usage of these technologies. Recently our group synthesized several anion exchange polymers via super acid catalyzed Friedel-Crafts polycondensation. These AEMs, BPN1-100, m-TPN1-100 and p-TPN1-100 showed excellent stability in alkaline medium due to the absence of labile aryl-ether bonds in the polymer backbone. Additionally, they also exhibit good ionic conductivities and mechanical properties. In order to further understand the effects of polymer backbone morphology in AEM properties another polymer FMN1-100 was synthesized. In this study, properties of the AEMs BPN1-100, m-TPN1-100, p-TPN1-100, and FMN1-100 (Figure 1) were evaluated and compared for the purpose of anion exchange polymer electrolytes. Furthermore, FMN2-60 and FMN2-50 containing dication side chains were synthesized and compared against FMN1-100 containing a monocation side chain. The effect of the backbone architecture and side chain cations on the AEM properties such as, ionic conductivity, water uptake ratio, mechanical properties, morphology, and alkaline stability were investigated to broaden the knowledge of polymer design for AEMs.

Figure 1
Direct Numerical Simulation of Electric Double Layer Formation in Supercapacitors
Authors: Qu Danqi , Termuhlen Robert , Yu Hui-Chia
Published: December 2020

We will present an innovative method to simulate the formation of electric double layers on complex electrode geometries. Electric double layers are omnipresent and affect the ionic diffusion in many natural systems. It plays the most crucial role in the energy storage of supercapacitors and electric-field desalination. Upon imposing an electrostatic potential, the cations and anions near the electrode surface separate to form a localized polarization counterbalancing the potential. The charge-separated region usually spans 20 to 50 nanometers, whereas other significant length scales, e.g., particle size or inter-particle space in electrodes, are in tens to hundreds of microns. A direct numerical simulation in the continuum scale requires to resolve the ionic concentration and potential gradients across 3~4 orders of magnitude in spatial scales and is incredibly challenging. Therefore, continuum-scale numerical studies are limited to one-dimensional or simple symmetric geometries, or in nanoscales where double-layer thickness and particle size are comparable. In this work, we use the smoothed boundary method that defines complex microstructures with a phase-field-order-parameter-like continuous function to reformulate the Nernst-Planck-Poisson equations and solve the equations on adaptively refined meshes. Thus, the method allows for accurately simulating the charge separation and potential distribution in arbitrarily complex geometries with resolutions spanning from nanometers in the double layer to micron/millimeters in the particle/electrode scales. Simulations of the dynamics during double layer formation and the resultant capacitance on complex electrode microstructures will be presented. The coupling of charge separation and fluid mechanics in simulating the electric-field desalination process through porous electrodes will also be discussed.

Figure Caption: Electrostatic potential in the electrolyte of the supercapacitor at different time after simulation begins (a) t = 0.133 ms (b) t = 0.266 ms (c) t = 0.532 ms and (d) t = 2.13 ms.

Figure 1
Influence of Oxygen Vacancy on Pseudocapacitance of La0.8Sr0.2CoO3-δ
Authors: Lannelongue Pierre , Abdollahifar Mozaffar , Wu Nae-Lih (Nick)
Published: December 2020

Since the discovery of the charge storage mechanism involving a charge compensation by anion that can happen for some pseudocapacitive materials, oxides from the perovskite family have been intensively studied during the past five years, such as LaMO3-δ (M = Mn, Fe, Co, Ni). The oxygen vacancy present in some perovskites naturally becomes the center of this new mechanism. Indeed, the vacancies are suggested to host oxygen/hydroxyl ions to compensate the oxidation of the transition metal, and to release these ions during the reduction. Interestingly, there has not been any report dedicated to reveal the correlation between the oxygen vacancy with the pseudocapacitance of these materials.

We propose here the study of the influence of the oxygen stoichiometry of the perovskite La0.8Sr0.2CoO3-δ, written as LSC82, used as pseudocapacitive electrode material. LSC82 has been prepared by a urea-nitrate combustion method, and then calcined at 850°C. Materials having different oxygen stoichiometries were obtained by different cooling rates. Electrochemical tests were performed on LSC82 based electrodes in 5M LiNO3 electrolyte to reveal the correlation between the oxygen stoichiometry and pseudocapacitve performance. The oxidation states of Co and the oxygen vacancies content in the various prepared LSC82 have been determined by various technics such iodometric titration, X-ray Absorption Spectroscopy and X-ray Photoelectron Spectroscopy. By associating electrochemical tests with spectroscopic technics, it is possible to connect oxygen vacancies content with electrochemical performances.

Understanding the role of oxygen vacancies could give new lead to improving the performances of such materials.
All-Solid-State Al – Graphene Hybrid Supercapacitor
Authors: Tak Yongsug , Seon Eunbin , Kim Isak
Published: December 2020

With the recent growth of interest in wearable electronics, gel electrolytes or solid electrolytes of energy conversion devices such as batteries and capacitors have been actively studied. All-solid-state supercapacitor has advantages such as high power density, outstanding mechanical stability, and long cycle life. However, the low energy density of supercapacitor makes it difficult to replace the battery. Therefore, a hybrid supercapacitor combining a battery and a supercapacitor has been significantly attracted.

In this study, aluminum as a battery electrode and graphene as a capacitor electrode were hybridized in a cell and ethyl acrylate and ionic liquid were used to make a polymer gel electrolyte. Aluminum has high energy density due to three-electron reaction and can be considered as a promising battery type electrode of a hybrid supercapacitor. Conversely, graphene is appropriate for capacitor type electrodes owing to its large specific surface area (~2675 m2 g-1) and high theoretical capacity (550 F g-1 ). With the increase of charge/discharge cycling, the dissolution and deposition reactions of aluminum were repeated and the contact of the aluminum anode and gel electrolyte decreases, which can result in a decrease in capacitance and cycle stability. Two strategic approaches were applied to improve the cell performance and charging-discharging behaviors were investigated with the variations of aluminum surface morphology. Firstly, aluminum metal was electropolished to remove the surface oxide film and applied as an anode. Secondly, thin aluminum metal film was prepared with electroplating and tested as an anode. Electrochemical Impedance Spectroscopy (EIS) was used to characterize the gel electrolyte and to measure the contact resistance between electrolyte and the surface-treated aluminum. SEM and XRD were used to analyze the aluminum surface structure.
(Battery Division Postdoctoral Associate Research Award Address Sponsored by MTI Corporation and the Jiang Family Foundation) Li Plating During Fast Charge: Detection and Prevention
Authors: Rodrigues Marco-Tulio , Abraham Daniel P.
Published: December 2020

Enabling fast charge of lithium-ion batteries is an essential step towards the wider adoption of electric vehicles. A key challenge is that high charging currents can promote several aging mechanisms, including lithium plating on the graphite anode. There is research suggesting that the deposition of metallic lithium favors further Li plating in a self-reinforcing loop, which can eventually lead to sudden cell failure.[1] Hence, detecting Li deposition during the early stages and developing electrochemical cycling protocols that avoid plating conditions are crucial to enabling fast-charge.

In this talk we will discuss two approaches to investigate Li deposition. The first one is through detection. Our group has demonstrated that plated Li can intensify the Raman signal of its surrounding SEI, which then serves as an indirect marker for the presence of Li nuclei.[2] The sensitivity of this technique enables the study of where Li will tend to plate, and how this deposition evolves spatially over the course of many cycles. The second approach is through the use of a reference electrode, which can be used to estimate electrode potentials during fast charging.[3] This capability supports the development of fast-charging protocols that optimize time utilization while steering the cells away from Li plating conditions. Examples of such cycling protocols will be discussed during the presentation.

References

[1] X.-G. Yang, Y. Leng, G. Zhang, S. Ge, C.-Y. Wang, Journal of Power Sources, 360, 28-40 (2017)

[2] M.-T. F. Rodrigues, V. A. Maroni, D. J. Gosztola, K. P. C. Yao, K. Kalaga, I. A. Shkrob, and D. P. Abraham, ACS Applied Energy Materials, 2 (1), 873-881 (2019)

[3] M.-T. F. Rodrigues, K. Kalaga, S. E. Trask, D. W. Dees, I. A. Shkrob, and D. P. Abraham, Journal of The Electrochemical Society, 166 (6), A996-A1003 (2019)

Acknowledgements:

We are grateful to the U.S. DOE Office of Vehicle Technology Extreme Fast Charge Cell Evaluation of Lithium-Ion Batteries (XCEL) Program managed by Samuel Gillard. This document has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”). Argonne, a U.S. Department of Energy Office of Science laboratory, is operated under Contract No. DE-AC02-06CH11357.
Analysis of the Impact of Fast Charging on Aging for Smartphone Cells: A Case Study Using Synchrotron Based Techniques
Authors: Besli Muenir Mustafa , Subbaraman Anantharaman , Ramezan Pour Safaei Farshad , Metzger Michael , Ravi Nikhil , Johnston Christina , Christensen Jake , Kuppan Saravanan
Published: December 2020

With the rapid market increase of consumer electronic devices such as smartphones and tablets, the performance of lithium-ion batteries (LIBs) in such devices becomes an important factor. In particular, fast charging, longer lasting batteries and safety are primary concerns for consumers. Lithium cobalt oxide (LCO) is a common cathode material for these applications, and in smartphone applications with 1-2 cycles a day, LCO has been proven to be a good cathode with its high cycle life.1,2 However, besides offering high cycling stability and power density for mobile consumer applications, another requirement for LIBs utilized in smartphones and other portable electronic devices is the capability of fast charging, without a detrimental impact on the cycling stability. Different fast charging profiles can lead to various extents of degradation within the full cell. Consequently, strategies are needed to avoid or mitigate any negative impact of fast charging on battery capacity, power degradation and cycle life.

In this work, we employed extensive synchrotron-based characterization methods on smartphone batteries (LCO/graphite), offering new insight into the various degradation mechanisms during fast charging. Specifically we focus on an in-house developed fast-charging profile based on a physics-based battery model and compare it with the fast charging profile provided by the OEM. We reveal how lithium plating occurring on the anode side during fast charging is ‘mirrored’ on the cathode side leading to inactive cathode areas that only participate partly in lithium intercalation. While no morphological changes were observed in the cathode opposing the plating sides on the anode, in-situ hard XAS spectroscopy shows that deactivated spots on the cathode are not as redox active anymore, and synchrotron micro XRD shows significant changes in the lattice d-spacing value. We conclude that a fast charging strategy derived from a physics-based model drastically reduces capacity fade and rate of impedance rise in a LCO/graphite smartphone cell as used in this work.

References

1 L. Wang, J. Ma, C. Wang, X. Yu, R. Liu, F. Jiang, X. Sun, A. Du, X. Zhou and G. Cui, Adv. Sci., 2019, 6,

1900355.

2 M. S. Whittingham, Chem. Rev., 2004, 104, 4271–4302.
(Invited) Capacitive and Pseudocapacitive Intercalation of Aqueous Ions in Layered Materials (MXenes)
Authors: Okubo Masashi , Yamada Atsuo
Published: December 2020

The development of efficient aqueous electrochemical energy storage (EES) devices is an important sustainability issue to realize green electrical grids. Although current nonaqueous EES devices operate through the intercalation chemistry of host electrode materials, capacitive or pseudocapacitive intercalation has recently emerged as an alternative chemistry for advanced aqueous EES devices. In particular, metal carbide/nitride nanosheets termed MXene are a promising class of intercalation capacitor and pseudocapacitor electrode materials. However, general design strategies of MXenes for aqueous EES applications have not been established because of the limited understanding of the complex electrochemical properties of MXenes with aqueous electrolytes. In this talk, using experimental and theoretical analyses, we clarify the anomalous dielectric properties of aqueous ions confined between MXene nanosheets, leading to the enhanced charge storage capability of MXenes with aqueous electrolytes. Furthermore, we demonstrate that the change of water activity in aqueous electrolytes largely alters aqueous-ion intercalation chemistry, which also influences the charge storage capability of MXenes.

References

Y. Ando, M. Okubo, A. Yamada, M. Otani, Adv. Funct. Mater., 2020, 202000820.

K. Kim, et al., M. Okubo & A. Yamada, Chem. Mater., 2019, 31, 5190-5196.

A. Sugahara, et al., M. Okubo & A. Yamada, Nature Commun., 2019, 10, 850.

M. Okubo, et al., & A. Yamada, Acc. Chem. Res., 2018, 51, 591-599.
A Self-Improved High-Capacitance Supercapacitor Based on Unstacking of Reduced Graphene Oxide Assisted By Lithium Salts of Tungstosilicic Acid
Authors: Yan Zhiwei , Zhou Xiangyang , Qiao Xiaoyao , Wang Yuchen , Zhang Chen , Akin Mert , Mansour Azzam N. , Waller Gordon H.
Published: December 2020

Abstract: Lithium salts of tungstosilicic acid (SiWLi) enriched with oxygen-containing functional groups were developed as an electrolyte for the prevention of reduced graphene oxide (rGO) restacking. The morphology and microstructure of SiWLi and rGO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The composite of SiWLi and rGO were fabricated and utilized as electrodes to assemble supercapacitors, which displayed significantly enhanced capacitance. The initial specific capacitance of this supercapacitor is 203 F g-1 at 10 mV s-1. After 2300 cyclic voltammetry tests it grew up to 297 F g-1 at 10 mV s-1. In addition, this self-improved supercapacitor exhibited excellent rate performance after 2300 cyclic voltammetry tests. The achieved specific capacitance is 271 F g-1 at 200 mV s-1, which is much higher than that obtained in the initial test (173 F g-1 at 200 mV s-1). The self-improved effect could be attributed to more activated rGO assisted by the synergistic electrochemical interaction between the electric double layer capacitance of rGO and the pseudocapacitance of SiWLi.