bluuebunny/crossref_metadata_2025 huggingface dataset:
Solution-Processable Electroactive Polymers As Active Materials for Macroscale Energy-Storage Devices with High-Rate Capability
Authors: Long Jeffrey W. , Sassin Megan B. , Ӧsterholm Anna , Reynolds John R
Published: February 2020

Electroactive polymers have long been investigated as prospective charge-storage materials for electrochemical capacitors and rechargeable batteries. Conventional synthetic routes to such polymers have relied on electrodeposition, typically as thin films at planar substrates, or solution-phase methods that yield precipitates, which can be difficult to incorporate into composite-electrode structures. Recently, the Reynolds group at Georgia Tech has developed a family of solution-processable electroactive polymers, whose solubility characteristics are tuned via side-chain derivatization of ProDOT and EDOT structures [1,2]. We exploit the tailorable solubility of these polymers to facilitate their incorporation into macroscopically thick carbon nanotube/nanofiber papers. By distributing the polymer as a thin coating on a 3D carbon-based current collector, the inherent high-rate character of the polymer is maintained while the capacitance/capacity per geometric footprint is amplified by factors of ten or greater compared to analogous thin films. The chemical nature of these polymers can also be varied to achieve charge-storage functionality in either aqueous or nonaqueous electrolytes, which expands the range of electrochemical device configurations that will benefit from these advanced electrode materials. To demonstrate the technological promise of polymer–carbon electrode architectures, we perform electrochemical tests in three-electrode cells and two-terminal devices, assessing such critical characteristics as rate-dependent capacitance/capacity, self-discharge, and cycle life.

1. Ponder Jr., J. F.; Österholm, A. M.; Reynolds, J. R. “Designing a Soluble PEDOT Analogue without Surfactants or Dispersants,” Macromolecules
49, 2106 (2016).

2. Österholm, A. M.; Ponder Jr., J. F.; Kerszulis, J. A.; Reynolds, J. R., “Solution Processed PEDOT Analogues in Electrochemical Supercapacitors,” ACS Appl. Mater. Interfaces
8, 13492 (2016).
(Invited) Materials Development for Organic Redox Flow Batteries
Authors: Wei Xiaoliang
Published: February 2020

Because of the excellent scalability and design flexibility, redox flow batteries are especially advantageous for grid-scale energy storage. Traditional inorganic-based flow batteries are generally limited by the low energy density and high chemical costs, which greatly restricted their widespread market penetration. In this regard, organic redox-active materials have been reported as possible materials alternatives to exhibit encouraging properties and performance.1
,2 The development of organic materials have suggested a promising avenue for enabling next-generation redox flow batteries, although further improvements are still urgently needed to demonstrate their commercialization potential.

In this presentation, we will introduce our recent progress in developing aqueous organic flow battery materials and systems. Among a variety of organic candidates being investigated, a few have demonstrated high effective electron solubilities >3 M, favorable redox potentials to enable high cell voltages, and highly scalable synthesis leading to cost-effectiveness. More importantly, we have achieved basic structure-property understandings of the key factors that govern the solubility and chemical stability of organic redox-active materials. These have provided guidance for rational materials design and development strategies to harvest significantly improved energy density and cyclability of flow batteries.

References

X. Wei, W. Pan, W. Duan, A. Hollas, Z. Yang, B. Li, Z. Nie, J. Liu,D. Reed, W. Wang, V. Sprenkle, Materials and Systems for Organic Redox Flow Batteries: Status and Challenges. ACS Energy Lett.
2017,
2, 2187.

A. Hollas, X. Wei, M. Vijayakumar, Z. Nie, B. Li, D. Reed, J. Liu, V. Sprenkle, W. Wang, A Nature-Inspired, Energy-Dense Phenazine-based Anolyte for Aqueous Organic Redox Flow Batteries. Nat. Energy, accepted.

Figure 1. Cycling efficiency and capacity for an aqueous organic flow battery.

Figure 1
Reliability of a Method of Electrochemical Impedance for the Determination of Milk Adulteration
Authors: Romero-Bonilla Hugo , Tinoco Oscar , Garay Diana , Mera Anshily , Jimenez Maydee
Published: February 2020

The objective of this research work was to determine the reliability of a electrochemical impedance spectroscopy method to determine the percentage of adulteration of milk with tap water. To measure the adulteration, the resistance in ohms was correlated with respect to the concentration of water in the milk. For this, a multichannel potentiostat was used. The milk was maintained at a temperature of 24 ° C. Five concentrations of tap water were used with respect to pure cow's milk, with values of 10, 15, 20, 25 and 30% v / v. A calibration curve was constructed from a sample of pure milk (unadulterated) as the reference standard. All readings were made by four repetitions at frequencies between 1 and 10000 hertz (Hz). From this, for each concentration of water in the milk through the Bode diagrams, a response of the resistance in ohms (Ω) was obtained as a function of the frequency (Hz). To determine the reliability of the method, linearity, precision, limit of detection and limit of quantification were determined. The linearity of the method was demonstrated from the coefficient of proportionality of 0.9975. The coefficient of variation (CV) had a value of 0.04%, which indicates that the accuracy of the method is acceptable. On the other hand, the limit of detection and limit of quantification correspond to values of 2.22 and 0.44% v / v respectively.
Synthesis and Characterization of Novel Polypyrrole/Cerium Oxide Nanocomposite Sensor for the Voltammetric Quantification of Flupirtine Maleate
Authors: Khan AB Lateef
Published: February 2020

The highly conducting and novel Polypyrrole/Cerium Oxide (Ppyl/CeO2) nanocomposite material was synthesized and characterized by various spectral (FTIR, XRD, SEM) and electrochemical methods (voltammetry) along with electron impedance spectroscopy (EIS). The spectral data as shown in figure 1 clearly describes the successful synthesis of the Ppyl/CeO2 nanocomposite material. The Ppyl/CeO2 nanocomposite was used to modify the glassy carbon electrode (GCE) for the fabrication of Ppyl/CeO2/GCE nanocomposite sensor. The electrochemical characterization of the Ppyl/CeO2/GCE along with its other modified forms viz CeO2/GCE, Ppyl/GCE including bare GCE confirms the successful fabrication of the nanocomposite sensor. The surface area, heterogeneous electron transfer (HET) rate constant (k0
eff), and charge transfer resistance of the fabricated sensor were also determined by cyclic voltammetry (CV) and EIS respectively. The fabricated sensor was further optimized to carry out the voltammetric quantification of the Flupirtine Maleate (FPM). The sensor under optimized experimental conditions exhibits a linear relationship over a concentration range of 100 ng mL−1 to 500 ng mL−1 with the correlation coefficient (r2) of 0.9940 for the oxidation of FPM. The limit of detection (LOD) and limit of quantification (LOQ) calculated from calibration curve was found to be 26.76 ng mL−1 and 89.20 ng mL-1 respectively. The results thus clearly demonstrated that the newly fabricated voltammetric nanocomposite sensor possesses an ultra sensitivity for the oxidation of FPM.

Figure 1
Development of Nanostructured Biosensors Toward Point-of Care Applications
Authors: Curtin Kathrine , Wu Nick
Published: February 2020

Biosensors are novel devices for offering fast, point of care results in healthcare and environmental fields compared to expensive, time-consuming laboratory instruments and techniques. Nanostructures have been shown improve the performance of biosensors. Nianqiang Wu’s research group explores biosensor signal transduction methods and sensor designs with nanostructure integration for detection of cancer biomarkers, heavy metals, and protein biomarkers. For example, plasmonic gold nanostructures, such as nanoarrays, nanostars and nanorods, have been demonstrated to amplify the surface-enhanced Raman scattering (SERS) signal in biosensors because of their unique optical properties and highly tunable localized surface plasmon resonance (LSPR). Fluorescence biosensors for resonant energy transfer have been explored using quantum dots, graphene oxide, and plasmonic nanostructures. The fundamental working principles and performance optimizations are extensively characterized and investigated in this group. Both fluorescence and SERS have been used in developing paper-based lateral flow and microfluidic, lab-on- chip biosensors for cancer biomarkers, heavy metals, and traumatic brain injury protein biomarkers.
Bacteria Sensors Based on Interdigitated Silicon Nanowires Electrodes
Authors: Salaun Anne-Claire , Le Borgne Brice , Pichon Laurent , Gougeon-Jollivet Anne , Martin Sophie , Rogel Regis , De Sagazan Olivier
Published: February 2020

The detection of pathogenic bacteria in food, water and air is an important issue because of its critical impact on public health, especially with the emergence of multi-resistant bacteria. Standard microbiological methods of bacterial culture impose deadlines that can slow down the establishment of means of protocols against contaminations. In this context, a strategy is to develop ultrasensitive sensors based on silicon nanowires networks for rapid detection of bacteria. Indeed, the nanowires have a large contact surface allowing preferential interactions with the bacteria. Resistors based on silicon nanowires used as bacteria sensors are fabricated using conventional silicon technologies. The nanowires are obtained by the VLS (Liquid Solid Vapor) method using gold as catalyst and the interdigited comb electrodes are made of high doped polycrystalline silicon. The bacteria are preferentially attached to the nanowire network (fig. 1a and b). The electrical characterization of the the devices shows that the current through the resistors increases significantly due to the presence of bacteria (fig. 1c). The results show the potential use of the resistors, with the nanowires as sensitive units, for the detection of bacteria.

Figure 1
Artificial Cilia for Microfluidics Particle Capture
Authors: Hanasoge Srinivas , Alexeev Alexander , Erickson Marilyn , Hesketh Peter J , Ortega Ynes R
Published: February 2020

Microorganisms use hair like cilia to perform various biophysical functions. Particularly they use cilia to manipulate fluid flow and generate currents that enable their feeding. Natural cilia are also used to sort particles before feeding. In this work, we demonstrate artificial cilia capable of capturing particles on its surface. Magnetic filaments are used as cilia, which extend away from the substrate and into the microfluidic channel. A sample of fluid containing the target bacteria is introduced into the channel. The cilia are actuated to perform bio-mimetic oscillations. The motions of the artificial cilia enhances fluid mixing and therefore increases the probability of contacting the target cells. The antibody immobilized cilia surface captures the target bacteria upon contact. We demonstrate the capture of Salmonella bacteria on the surface of the cilia, from a sample from washing of leafy greens. The results presented in this work demonstrate the feasibility of antibody functionalized cilia to perform capture. The cells are selectively shown to attach to the surface of the cilia. This mechanism can be extended to pre-concentrate of other target cells.
Piezoelectric Micro- and Nanostructured Fibers Fabricated from Thermoplastic Nanocomposites Using a Fiber Drawing Technique: Comparative Study and Potential Applications
Authors: Lu Xin , Qu Hang , Skorobogatiy Maksim
Published: February 2020

We report an all-polymer flexible piezoelectric fiber that uses both judiciously chosen geometry and advanced materials in order to enhance fiber piezoelectric response. The microstructured/nanostructured fiber features a soft hollow polycarbonate core surrounded by a spiral multilayer cladding consisting of alternating layers of piezoelectric nanocomposites (polyvinylidene enhanced with BaTiO3, PZT, or CNT) and conductive polymer (carbon-filled polyethylene). The conductive polymer layers serve as two electrodes, and they also form two spatially offset electric connectors on the fiber surface designed for the ease of connectorization. Kilometer-long piezoelectric fibers of sub-millimeter diameters are thermally drawn from a macroscopic preform. The fibers exhibit high output voltage of up to 6 V under moderate bending, and they show excellent mechanical and electrical durability in a cyclic bend−release test. The micron/nanosize multilayer structure enhances in-fiber poling efficiency due to the small distance between the conducting electrodes sandwiching the piezoelectric composite layers. Additionally, the spiral structure greatly increases the active area of the piezoelectric composite, thus promoting higher voltage generation and resulting in 10−100 higher power generation efficiency over the existing piezoelectric cables. Finally, we weave the fabricated piezoelectric fibers into technical textiles and demonstrate their potential applications in power generation when used as a sound detector, smart car seat upholstery, or wearable materials.
Catalytic Polymer Membranes and Coatings for the Immobilization, Detection, and Conversion of Toxic Agents in Humid Environments
Authors: Angelopoulos Anastasios P.
Published: February 2020

Sulfonated polymers such as sulfonated polystyrene (sPS) and perfluorosulfonic acid (PSA) based materials have been of long-standing interest as sustainable solid acid catalyst alternatives to toxic homogeneous acid catalysts in the production of high-volume specialty chemicals. Our interest in these materials arises from the potential use of their uniquely heterogeneous hydrophobic-hydrophilic morphology for wearable chemical sensing in personal protective equipment (PPE). Sulfonated polymers can be applied as durable coatings on fiber blends using coaxial electrospinning to produce non-woven fabrics or onto polymeric Gore® woven textiles. Prior research with these materials did not consider their catalytic properties and determined that water as liquid or vapor from sweat can actually promote chemical warfare (CW) agent transport. We demonstrate that the interface between dispersed hydrophilic clusters and the hydrophobic matrix of sulfonated polymers can be exploited to introduce catalytically active sites that trap and convert CW agents to a non-toxic organophosphate ester already used commercially as a flame retardant in clothing. Such trapping and conversion would not interfere with water transport and the associated color change provides a simultaneous means for optical detection. Despite significant understanding of how PSA polymer morphology impacts the transport behavior of ions, uncertainty remains over why some organic molecules become immobilized as they diffuse and react in this important class of materials while others do not. These aspects will be discussed in this presentation.

Figure 1
(Invited) Emerging Materials for Additive Manufacturing of Flexible Hybrid Sensors
Authors: Estrada David
Published: February 2020

Recent advances in the synthesis of 2-dimensional (2D) materials-based inks has increased the design space for additive manufacturing of flexible hybrid electronics (FHE) and sensors. Such systems stand to benefit from high performance flexible silicon IC’s for signal processing and amplification, while also leveraging the high surface area and unique physical properties of 2D materials as sensor electrodes. For example, previous work has elucidated the fundamental role of crystal defects in the sensing mechanisms of graphene chemiresistors, however, such sensors are yet to find widespread commercial application. Integration of graphene with flexible silicon ICs could help expedite the adoption of such sensors in industry, as sensor response to target analytes could be isolated from other environmental factors through rapid signal processing techniques. Furthermore, advances in additive manufacturing of such systems could further enable widespread adoption of FHE’s for applications requiring on-demand manufacturing and repair of sensors and systems. Towards this end, the Advanced Nanomaterials and Manufacturing Laboratory at Boise State University has undertaken several projects to help overcome obstacles facing the integration of 2D materials with FHE systems and sensors. This talk will highlight results of several ongoing studies on the integration of 2D materials with flexible silicon ICs including limiting factors of power dissipation in printed graphene electrodes, the electrochemical response of fully printed graphene electrochemical sensors, and the reliability of flexible silicon die attach strategies for FHE system integration.
Systematic Development of Positive Active Materials for Nonaqueous Redox Flow Batteries Using Phenothiazine As a Learning Platform
Authors: Kowalski Jeffrey A , Attanayake N. Harsha , Odom Susan A. , Brushett Fikile R.
Published: February 2020

There is an increasing demand for stationary energy storage systems to facilitate the integration of intermittent, renewable energy sources (e.g. wind, solar) and to improve the efficiency, reliability, and resiliency of the existing fossil fuel infrastructure. Redox flow batteries (RFBs) are electrochemical energy storage devices that are well suited for grid storage due to decoupled power and energy scaling, long operating lifetimes, and simplified manufacturing1. While state-of-the-art RFBs utilize transition metal salts to store energy, they are currently too expensive to meet the stringent targets set by the U.S. Department of Energy ($100/kWh)2, motivating research in novel organic charge storage materials which may enable a pathway to low cost through tunable molecular structure and inexpensive synthesis routes3.

This work focuses on the use of phenothiazine and its derivatives as a robust learning platform to investigate the impact of substituent group addition on the molecular properties with an overarching goal of developing structure-function relations that enable deterministic multi-property optimization. Specifically, we seek to improve the equivalent charge concentration of redox electrolytes containing phenothiazines, by enhancing the solubility and intrinsic storage capacity through a combination of molecular engineering and electrochemical analysis. Building from N-ethylphenothiazine, we find judicious application of substituent groups can lead to significant performance enhancements, but care must be taken to avoid improving one property at the expense of others.

References

A. Z. Weber et al., J. Appl. Electrochem., 41, 1137–1164 (2011).

A. A. Akhil et al., Ed Albuq. NM Sandia Natl. Lab. (2013) http://www.emnrd.state.nm.us/ECMD/RenewableEnergy/documents/SNL-ElectricityStorageHandbook2013.pdf.

J. A. Kowalski, L. Su, J. D. Milshtein, and F. R. Brushett, Curr. Opin. Chem. Eng., 13, 45–52 (2016).
Recovery of Gold Using Silicon Powder from Leaching Solutions
Authors: Arita Shotaro , Tsuda Takuya , Fukuda Kenji , Matsumoto Ayumu , Yae Shinji
Published: February 2020

Low cost and efficient recovery of noble metals from urban mines (e.g., used electronic equipments) is important for securing scarce resources. We are developing a noble metal recovery technology utilizing electroless displacement deposition on silicon (Si)1. In this method, noble metals can be recovered by adding Si powder in metal salt solutions containing hydrofluoric acid (HF)2,3. For safety concerns, we are considering the use of highly basic solution instead of toxic HF solution. We have reported the effects of solution pH on the gold recovery from a basic solution4. In the practical applications, gold is recovered from leaching solutions. In this study, we examined the gold recovery from a basic solution simulating a thiosulfate-based leaching solution.

0.20 M (M: mol dm-3) Si powder (Kojundo Chemical Laboratory, 99.99%) with a particle diameter of 45 μm or less was added to a simple basic solution of 1 mM hydrogen tetrachloroaurate (III) solution pH-adjusted with sodium hydroxide, or a simulated leaching solution containing 1 mM sodium gold (I) sulfite, 1 M ammonium thiosulfate, 1 M ammonium hydroxide, and 0.5 mM copper (II) sulfate, which solution pH was at 9.3. The solution was stirred at 200 rpm using a magnetic stirrer and kept at 298 K of temperature. After filtering the solution, the concentrations of the metal in the filtrate were measured by an ICP-AES (Hitachi, SPS7800) and the recovery was determined from the change in concentration before and after the recovery process.

Figure 1 shows the recovery of gold from the simple basic solution (Fig. 1a) and the simulated leaching solution (Fig. 1b). The recovering rate form the simple basic solution was increased with solution pH. The long time treatment at the solution pH of 8 for 24h increased the recovery to 100%. Using bare Si powder, which was pretreated with a HF solution for dissolving an oxide layer on Si surface, shortened the treatment time to 45 min for getting 100% of recovery from the solution at the pH of 8. These results indicate that Si oxide layer inhibits gold recovery from the basic solution without fluoride species. The recovery of gold from the simulated leaching solution increased with treatment time and reached 98% or more at the treatment time of 120 min (Fig. 1b). The recovery of copper, which was added as the oxidation aid, was less than 10%. This suggests the possibility that gold is selectively recovered from the leaching solution including less noble metal than gold.

ACKNOWLEDGEMENT

The present work was partly supported by JSPS KAKENHI (JP26289276).

REFERENCES

S. Yae, N. Nasu, K. Matsumoto, T. Hagihara, N. Fukumuro, and H. Matsuda, Electrochim. Acta, 53, 35 (2007).

K. Fukuda, S. Yae, N. Fukumuro, S. Sakamoto, and H. Matsuda, ECS. Trans.,
53(19), 69 (2013).

K. Fukuda, N. Fukumuro, S. Sakamoto, and S. Yae, ECS. Trans.,
61(10), 1 (2014).

K. Fukuda, S. Arita, T. Tsuda, A. Matsumoto, and S. Yae, J. Surf. Finish. Soc. Jpn.,
69(6), in press (2018).

Figure 1
Improvement of Water Resistance of a Proton Conducting Phosphate Glass Electrolyte By Addition of ZnO or CaO
Authors: Shida Atsushi , Ogasawara Kiya , Shiroishi Hidenobu , Saito Morihiro , Tanaka Yumi
Published: February 2020

Introduction

　CsH2PO4 (CHP) has been studied as a solid electrolyte for an intermediate-temperature fuel cell. It shows relatively high proton conductivity (10–2 Scm-1) in the intermediate temperature (100–300℃) range. However, humidification is necessary to maintain the crystal structure of CHP, and water resistance is extremely low. We reported that proton conducting glasses (CHP-PO4) made from CHP and phosphoric acid shows high proton conductivity and excellent water resistance compared with CHP under dry N2. However, the water resistance of the phosphate glasses needs to be improved for application to solid electrolytes. Metal oxides such as CaO and ZnO are often added for improving the water resistance of glass. Thus, in this study, we attempted to further improve the water resistance by adding the above metal oxide to CHP-PO4. The effect on proton conductivity was also evaluated by AC impedance measurements.

Experimental

　CHP was synthesized according to the literature1. A phosphate glass electrolyte was prepared by mixing CHP and 85 wt% H3PO4 at a molar ratio of 1: 1 and heating at 500 °C for 5 min, then raising the temperature to 900 °C for 15 min. The obtained melt was spread out on a copper plate heated at 180 °C, and quenched to obtain a phosphate glass electrolyte. Ca or Zn containing glasses (abbreviated as CHP-x(CaO or ZnO)-PO4) were prepared as follows: CHP, H3PO4 and ZnO or CaO were mixed in Cs : (Zn or Ca) molar ratios of 1: x and melted and quenched under the same conditions as mentioned above. Raman spectra were measured using NRS3100 (JASCO Co. Ltd.). The proton conductivity of the electrolytes was measured by an AC two-terminal method under dry nitrogen using an impedance analyzer (Yokogawa, HP-4192A). The water resistance test was conducted by the following method: The sample was immersed in 200 mL of ultrapure water with stirring at 100 rpm, and the amount of eluted hydrogen ions per unit surface area of the sample was determined with a pH meter (CUSTOM Co. Ltd, IWC-5).

Results and discussion

The results of the water resistance test of phosphate glass electrolytes are shown in Fig. 1. It was revealed that increase in the ZnO or CaO ratio in the samples results in the improvement of the water resistance.

　The proton conductivities of the samples containing Zn or Ca were lowered to 10–3–10–4 S cm–1. Raman spectroscopic analysis of the phosphate glass revealed that the peak derived from ν(PO2)syn of the phosphate glass in CHP-x(CaO or ZnO)-PO4 shifted to the higher frequency by about 10 cm-1, which is attributable to the shorter phosphate chain. The present result suggested that the metal ions cross-linked phosphate chains and contribute the improvement of water resistance for the electrolytes.

Reference

1. Qing et al., Electrochim. Acta, 169, 219–226, (2015).

Figure 1
Understanding Mechanisms of Membrane Degradation in Membrane Electrode Assemblies with Ultra-Low Platinum Loadings
Authors: Spears Andre , Rockward Tommy , Martinez Ulises , Mukundan Rangachary , Garzon Fernando H
Published: February 2020

Further commercialization of fuel cell technology remains to be hindered by the challenges encountered to fulfill the DOE cost, performance, and durability targets for automobile applications. In order to meet performance targets, platinum (Pt) continues to be the catalyst of choice for both electrodes. However, in order to meet the 2020 DOE cost target of $14/kWnet total Pt loadings need to be reduced to less than 0.125 mgPtcm-
2 while maintaining sufficient performance. In this work, we will develop a better understanding about the mechanisms of membrane degradation in membrane electrode assemblies (MEAs) as a function of catalyst loading. Specific emphasis were devoted to ultra-low Pt loadings, i.e., <0.1 mgPt cm-2, with symmetric anode and cathode loadings verified via X-ray fluorescence (XRF). Established accelerated stress tests (ASTs) were utilized to study chemical membrane degradation in MEAs using ion chromatography of effluent water samples collected at various times for the quantification of fluoride emission rates (FER). Membrane thinning was characterized via hydrogen crossover measurements as well as scanning electron microscopy (SEM) and X-ray computed tomography (XCT). Additionally, FER was probed as a function of varying testing conditions, e.g., temperature, relative humidity.
Catalytic Reduction of α,ω-Dihalohexanes By Electrogenerated Nickel (I) Salen in Dimethylformamide
Authors: Wang Zhiyang , Mubarak Mohammad S. , Peters Dennis G
Published: February 2020

A previous study has described that [[2,2′-[1,2-ethanediylbis(nitrilomethylidyne)]bis[phenolato]-N,N′,O,O′]nickel(I), also known as nickel(I) salen, can be electrogenerated from nickel(II) salen. Through the use of controlled–potential electrolysis, nickel(I) salen can catalytically reduce α,ω-dihaloalkanes. Early work focused on reduction of α,ω-dihaloalkanes substituted by mixed halogens, and revealed that this reduction could yield both straight-chain monomeric and dimeric products.1 This research project involves the catalytic reduction of 5.0 and 10.0 mM solutions of 1,6-dibromohexane and 10.0 mM 1,6-diiodohexane by nickel(I) salen electrogenerated at a glassy carbon cathode in dimethylformamide containing 0.10 M tetramethylammonium tetrafluoroborate (TMABF4) as a supporting electrolyte. A point of major interest is to separate, identify, and quantitate the products that arise from this catalytic process. Cyclic voltammetry indicates that the reduction peaks for 1,6-dibromohexane are –1.64 V for direct reduction and –0.92 V in the presence of nickel(I) salen; all potentials are reported versus a cadmium mercury amalgam reference electrode with a potential of –0.76 V versus an aqueous saturated calomel electrode. Reduction potentials for 1,6-diiodohexane are –1.56 V and –0.97 V, respectively. Bulk electrolysis of nickel(II) salen in the presence of these substrates has been performed, and the various products were separated and identified with the aid of gas chromatography–mass spectrometry and electrospray ionization–mass spectrometry. The results revealed that there were small amounts of cyclohexane and dihalogenated dimers with a significant amount of starting material left after electrolysis. This low yield is assumed to be from the alkylation of the imino bond on the salen ligand on the basis of previous studies; dihaloalkylated salen species were identified with the aid of liquid chromatography–mass spectrometry.1,2

Reference:

Mubarak, M. S.; Peters, D. G., Homogeneous Catalytic Reduction of α,ω-Dihaloalkanes with Electrogenerated Nickel(I) Salen. Electroanal. Chem.
1995,
388, 195–198.

Martin, E. T.; McGuire, C. M.; Peters, D. G., Catalytic Reduction of Organic Halides by Electrogenerated Nickel(I) Salen. Soc. Interface
2016,
25, 41–45.
Improving the Cycling Stability of Sodium Metal Electrode By Making an Sodium-Carbon Composite Electrode
Authors: Kim Yun-Jung , Kim Hee-Tak
Published: February 2020

The use of metallic anodes such as lithium and sodium has attracted large attention in the battery field because of their extremely high specific capacity and low operation potential. Indeed, the formation of metal dendrite upon repeated electrochemical plating/stripping cycling was early identified as obstacle of the development of safe metal anode secondary batteries. Also, due to dendrite formation, the low cycle efficiency and unstable cycle life happen, which hinder their practical application as anode materials. Therefore, to suppress the growth of metal dendrite is one of the most critical issues from a practical view point.

Recently, lithium metal has been extensively researched as anode candidate for secondary batteries due to its lowest redox potential and highest specific capacity among metallic anodes. Despite these promising properties, lithium sources are relatively limited and unevenly distributed across the globe, which lead to high costs of lithium metal batteries. Therefore, inevitably, lithium-based batteries will become unaffordable and large-scale production will falter. Therefore, sodium (Na) is one of the promising alternatives to lithium for energy storage technologies because of its relatively high theoretical specific capacity of 1166 mAh g-1 and natural abundance. Also, it has comparable redox potential, that is -2.70 V vs. SHE. However, like lithium metal anode, inhomogeneous electrochemical deposition of Na is a crucial problem that have to be solved for the usage of sodium metal as anode safely. Furthermore, Na metal has extremely high reactivity with liquid organic electrolyte, so high interfacial resistance could be induced due to continuous electrolyte decomposition during battery cycling, which also leads to earlier cell failure.

In this research, we present a stabilized sodium electrode by introducing electrically connected carbon network (ECN) to a bulk Na electrode with a simple folding & rolling method. As a results of introducing ECN, we observed that a cell overpotential was decreased as the amount of ECN inside bulk Na metal was increased. Also, we found that the cycling stability of Na/Na symmetric cell with ECN was almost 4.5 times increased compared to bare Na/Na cell, which is consistent with the results of EIS during cycling. By using SEM and CA analysis, we confirmed that an introduced ECN could act as not only an electrical network but also artificial uniform seed for Na nucleation.
Investigation of New Electrolyte Additives for Improvement of Nickel-Rich Cathode Materials at High-Voltage in Lithium Ion Batteries
Authors: Klein Sven , Winter Martin , Placke Tobias
Published: February 2020

The continuous optimization of lithium ion batteries regarding the energy density, cycle life and safety has enabled their widespread application various fields, such as for electric vehicles. To satisfy the ever-increasing demands on both high gravimetric and volumetric energy density, high voltage and high capacity materials are being intensively studied. Promising candidates are the Ni-rich layered LiNixCoYMn1-x-yO2 materials. High Ni content LiNixCoyMn1-x-yO2 materials are attracting more attention in the last years due to their high specific capacity.

Compared to the other commercial cathode materials, e.g. LiFePO4, LiCoO2 and Li-rich materials, the high Ni content LiNixCoyMn1-x-yO2 materials such as LiNi0.5Co0.2Mn0.3O2 (NMC-532) possess high specific capacity ca. 200 mAh g-1 at a cut-off potential of 4.6 V vs. Li/Li+.(1)

However, the oxidative decomposition of conventional carbonate-based electrolytes at high voltages ( > 4.5 V vs. Li/Li+) and the deterioration of the active material particles result in rapid capacity fading. Different strategies are known to improve the cycle life of the high voltage cathode material NMC-532. One opportunity is to protect the cathode surface by inorganic coatings. Su et al. demonstrated the use of an Al203 coating which resulted in a significant improvement of the cycle life of NMC-532 by minimizing the structural transformation (2). A further option to improve the cycle life of NMC-532 is to use electrolyte additives (3). On the basis that the added additive decomposed prior to the electrolyte components, a cathode electrolyte interface (CEI) layer is formed on the cathode particles. This CEI layer on the cathode can prevent the electrochemical and chemical oxidation of the electrolyte.

In this work, we present the combination of both an inorganic coating and the use of electrolyte additives to significantly improve the cycle life of NMC-532/graphite LIB full cells at 4.6 V vs. Li/Li+.

References:

(1)Yan, G., et al. (2015). "Effects of 1-propylphosphonic acid cyclic anhydride as an electrolyte additive on the high voltage cycling performance of graphite/LiNi0.5Co0.2Mn0.3O2 battery." Electrochimica Acta 166: 190-196.

(2)Su, Y., et al. (2015). "Enhancing the High-Voltage Cycling Performance of LiNi0.5Mn0.3Co0.2O2 by Retarding Its Interfacial Reaction with an Electrolyte by Atomic-Layer-Deposited Al2O3." ACS Applied Materials & Interfaces 7(45): 25105-25112.

(3)Lee, S. H., et al. (2018). "[4,4′-bi(1,3,2-dioxathiolane)] 2,2′-dioxide: A novel cathode additive for high-voltage performance in lithium ion batteries." Journal of Power Sources 378: 112-118.
Ionic Conductivity Studies of Ruddlesden-Popper Layered Perovskite with PEO As a Composite Solid Electrolyte
Authors: Prakash Ramakrishnan , Kwak Hunho H , Kim Jae Hyun
Published: February 2020

We report on ionic conductivity studies of three different Ruddlesden-Popper layered perovskite (RP-LP) materials such as Li2SrTa2O7, Li2SrNb2O7, and Li2CaTa2O7 in composite with polyethylene oxide composite. The developed RP-LP materials of n=2 in AnA’BnO3n+1 general crystal structure presents a two-dimensional lithium (Li+) ion conduction pathway is simulated using bond valence sum mapping. The temperature dependence of conductivity is modelled using the Vogel-Tamman-Fulcher (VTF) -type relationship for PEO RP-LP and pure PEO samples. The PEO RP-LP composites deliver the ionic conductivities in the range of 3.32 to 4.09 x 10-06 σ cm-2 at 80°C, and their corresponding activation energies in the range of 6.37 to 7.01 kJ mol-1 at the calculated temperature slope range of 50 to 80°C. They also deliver appreciable lithium transference numbers of 0.20 to 0.58 at 30°C and an excellent wide potential window stability of 4 V.
(Invited) Supply Chain Considerations for Lithium-Ion Battery Materials
Authors: Olivetti Elsa A , Ceder Gerbrand
Published: February 2020

Many energy storage technologies are fundamentally “materials-dependent”; they are enabled directly by, or designed around, a particular material or materials. Society's acute dependence on materials has increased in recent years as these technologies tap into an ever broader range of the periodic table and, therefore, into a broader set of underdeveloped and complex supply chains. In particular, growth in lithium-ion battery (LIBs) materials for the transportation and electricity sectors has led to extensive discussion of whether raw materials supply will meet the material requirements for these batteries. This presentation will cover balance between supply and demand for the metal content associated with compounds used in LIBs. We investigate the supply of nickel, cobalt, and lithium over the next 10 years and overlay scenarios of projected demand for LIBs over the same time period. We find that nickel has sufficient supply to meet the anticipated increase in demand for LIBs, but that there may be challenges in rapidly scaling the use of materials associated with lithium and cobalt in the short term. Due to long battery lifetimes and multiple end uses, recycling will play a modest role in filling the gap in short-term supply. We also explore the risks associated with the geopolitical concentrations of these elements, particularly for cobalt. Based on this initial screening, we perform a more detailed assessment of how cobalt supply may develop in the future particularly based on the byproduct nature of primary cobalt extraction from nickel and copper.
(Invited) Mesoscale Insights into Electrode Thermal Behavior for Li-Ion Battery Safety
Authors: Mukherjee Partha P. , Mistry Aashutosh N
Published: February 2020

Thermal implications continue to remain a challenge and critical determinant for safe and reliable operation of Li-ion batteries in high-energy/-power applications, such as electric vehicles. Unwanted local temperature excursion, due to self-heating and/or under abuse scenarios, may lead to thermal runaway. Thermo-electrochemical interactions in porous electrodes play a critical role, which dictate thermal localization and extremes during operation. While system-level thermal management targeted for effective heat distribution and dissipation are typical strategies for Li-ion battery safety, the implications of electrode-level thermo-electrochemical interplay are not well understood. In this presentation, mesoscale underpinnings of electrode interface and microstructural attributes will be examined in the context of lithium-ion battery thermal characteristics and safety.
Thermal Stability Study of Commercial Lithium-Ion Batteries As a Function of Cathode Chemistry and State-of-Charge
Authors: Ferreira Summer , Barkholtz Heather , Ivanov Sergei , Lamb Joshua , Langendorf Jill , Chalamala Babu R.
Published: February 2020

The safety of lithium-ion batteries is mainly quantified by thermal runaway characteristics such as onset temperature, peak heating rate (HR), and maximum pressure release. This talk evaluates the materials aspects of thermal runaway of commercial lithium-ion batteries by correlating the contributions from individual cell components to thermal runaway trends. An accelerating rate calorimeter was used to define the thermal runaway behavior of three commercial 18650 lithium-ion batteries (LiCoO2, LiFePO4, and LiNixCoyAl1-x-y­O2) at various states of charge (SOC). Cells were also disassembled and the thermal properties of their component materials was evaluated by thermogravimetric analysis, differential scanning calorimetry, and temperature-resolved X-ray diffraction. Broadly, lithium-ion battery thermal runaway process begins with solid-electrolyte interface and negative active material decomposition followed by the positive active material breakdown. The experimental results show that the onset temperature is generally independent of SOC and peak HR increases with SOC as a result of cathode destabilization. Overall, LiNixCoyAl1-x-yO2 decomposes readily, and charged LiCoO2 is also metastable, although it decomposes more gradually than LiNixCoyAl1-x-y. Contrary to the layered transition metal oxides, LiFePO4 is stable to > 500oC, even when charged. The results are aimed at informing future engineering and fire protection of commercial lithium-ion batteries.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. SAND2018-3360 A
Electrochemical and Mechanical Driving Forces for Lithium Electrodeposition
Authors: Jana Aniruddha , Woo Sang Inn , Vikrant Karra Suryanaryana , García R. Edwin
Published: February 2020

It is well documented in the scientific literature that lithium electrodeposits grow into elongated "dendritic" structures from the top (tip-controlled) at high current densities and into mossy structures from the base (base-controlled) under low current densities [1,2]. In order to physically understand base-controlled growth, first an analytical model has been developed to incorporate the thermodynamic and kinetic driving forces of lithium to describe the multiphysical electrodeposition kinetics of lithium. Given the charging current density, the following regimes of lithium growth behavior are readily predicted from the analytical framework: (i) thermodynamic suppression regime, (ii) incubation regime, (iii) tip-controlled regime, (iv) base-controlled regime, and (v) mixed growth regime. These regimes explain the experimental observations and provide the kinetic boundaries between tip- and base-controlled growth [3]. Further, numerical calculations demonstrate that high von Mises stresses in localized regions of the lithium whisker extrude lithium and lead to base-controlled growth. In addition, the complex multiphysical dendrite-dendrite electro-chemo-mechanical interactions are rationalized through local electric fields, electrodeposition rates, mechanical stresses, and plastic velocities that are otherwise difficult to visualize in-situ in experiments. Overall, the combined analytical and the numerical frameworks provide multiphysical insight and serve as a design guideline for dendrite-free rechargeable batteries.

[1] O. Crowther, A. C. West. “Effect of electrolyte composition on lithium dendrite growth.” Journal of the Electrochemical Society, 155, A806-A811 (2008).

[2] P. Bai, J. Li, F.R. Brushett, M.Z. Bazant. “Transition of lithium growth mechanisms in liquid electrolytes.” Energy & Environmental Science, 9, 3221-3229 (2016).

[3] A. Jana, R.E. García. “Lithium dendrite growth mechanisms in liquid electrolytes.” Nano Energy, 41, 552-565 (2017).
(Invited) Atomic Scale Simulations of Interfacial Phenomena in Solid Electrolytes
Authors: Siegel Donald J
Published: February 2020

There now exist a handful of solids that exhibit sufficient mobility of Li-ions to be considered viable electrolytes for battery applications. While these are exciting developments, recent research has shown, however, that high ionic mobility is in itself insufficient -- several other properties of a solid electrolyte are essential for use in electrochemical environments. Key amongst these are interfacial properties, which include stabilitiy, charge transport, wettabiity, and elastic properties. This presentation will summarize our recent computational studies of multiple interfacial issues in the promising solid electrolyte, LLZO. A wide range of computational methods are brought to bear on these phenomena; coupling to experimental measurements will be highlighted.
(Invited) Ionic Liquids at Electrified Interfaces: From Double Layers to Decomposition
Authors: Haskins Justin B , Yildirim Handan , Bauschlicher Charles , Lawson John W
Published: February 2020

Ionic liquids are versatile electrolytes whose properties at electrified interfaces have the potential to enable technologies such as supercapacitors and Li-metal battery anodes. At electrified carbon surfaces, ionic liquids form an electric double layer that stores energy and provides the foundation for supercapacitors. At electrified lithium surfaces, certain ionic liquids decompose to form a solid electrolyte interphase that has the potential to stabilize Li-metal anodes in rechargable batteries. The behavior of two ionic liquids of technological importance, [pyr14][TFSI] and [EMIM][BF4], are examined at these electrified interfaces through molecular dynamics and ab initio techniques.
Elucidating Mechanisms of Li Plating on Li Anodes of Lithium-Based Batteries
Authors: Qin Xueping , Shao Minhua , Balbuena Perla B
Published: February 2020

Lithium metal is known as a promising anode material for lithium-based batteries, which possesses an extremely high theoretical capacity.1 The Li dendrite growth during the cycling of the battery has prevented it from being used as the anode directly.2 The origins of dendrite formation may be associated with the mechanisms of Li plating and with the mode of charge transfer during Li reduction or oxidation at the anode-electrolyte interface.3

Herein, density functional theory (DFT) calculations were conducted to analyze the electron transfer between Li (100) and Li cations located in the proximity of the surface in several simulation models. The study includes two common used solvents: ethylene carbonate (EC) and dimethoxyethane (DME), and a LiPF6 salt, which surround the Li cation over perfect, defect-containing and the Li2CO3 passivated Li (100) surfaces. Figure 1 shows the Li deposition on three-Li defect Li (100) surface. Three possible positions for the introduced Li cation were considered (as indicated A, B, and C, respectively in Figure 1a). The calculation results showed that the hollow site is the preferred deposition site (Figure 1b), which is in good agreement with the result of Li deposition on perfect Li (100) surfaces. Figure 1c shows the Bader charges of three defect Li and one introduced Li cation (red circled), located in the large electron-accumulation area. This added cation receives electrons and has a Bader charge of 0. In the other word, it was reduced and plated on the Li metal surface.

Our calculations demonstrate that the Li cation is easily reduced when bonding to DME rather than EC. Additionally, a compact Li2CO3 layer inhibits the charge transfer from Li metal to Li cations, thus manipulating the Li plating process. Furthermore, the diffusing and plating of Li cations through other SEI components, including LiF, Li2O and LiOH, will be studied to illustrate the protective role of coating layers.

References

(1) Kim, H.; Jeong, G.; Kim, Y.-U.; Kim, J.-H.; Park, C.-M.; Sohn, H.-J. Chemical Society Reviews
2013, 42, 9011.

(2) Xu, W.; Wang, J.; Ding, F.; Chen, X.; Nasybulin, E.; Zhang, Y.; Zhang, J.-G. Energy & Environmental Science
2014, 7, 513.

(3) Love, C. T.; Baturina, O. A.; Swider-Lyons, K. E. ECS Electrochemistry Letters
2015, 4, A24.

Figure 1. (a) side view and top view of three-Li defective slab (three possible deposition sites for Li cations are marked as A-top, B-bridge and C-center, respectively); (b) the most stable optimized deposition structure for the introduced Li cation; (c) charge density distribution for the most stable structure; the corresponding Bader charges (black numbers) of the three defect Li atoms and reduced Li are shown. In the charge density distribution diagrams, yellow represents the electron-accumulation area, while cyan is the electron-depletion area.

Figure 1