bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) 13 Vitamins on a Potential Axis
Authors: Lovander Matthew Douglas , Parr Daniel Lee , Parke Brenna , Lyon Jacob , Leddy Johna 
Published: February 2020

Of the vitamins identified by the National Institutes of Health, all 13 are electroactive. Vitamins serve as enzymes and coenzymes in metabolic reactions. As catalysts and co-catalysts, vitamins neither provide energy nor serve as structural components of larger molecules.
The formal potentials E0' for the vitamins near physiological pH are plotted on a potential axis [1] as shown in Figure 1. The potential axis provides perspective on the energetics of various species. For example, E0' for the four lipid soluble vitamins A, D, E, and K lie outside potential window for water at pH 7. Vitamin C and all the B vitamins are water soluble, with vitamins C and B12 near the middle of the water window.
Review of the literature reveals the vitamins are grouped mechanistically as single electron transfer reagents (B3, B7, B2, C, and D), vitamins that can be both oxidized and reduced (B1, B5, B6, B9, and E), and vitamins that undergo two successive and distinct reductions (B12 and K). Mechanistically, vitamin A is most complex.
The potential axis and voltammetric mechanisms provide tools to assess and compare various properties of the vitamins. This includes:

Electrochemical stability in air, water, and acid

Antioxidant characteristics that include interactions with reactive oxygen species (ROS)

Electrochemical instability of vitamin pairs

Possible cooperative interactions between vitamins in health and medicine

Possible mechanisms for vitamin recycling in situ

For electrochemical mechanisms that are composed of electron transfer steps (E) and chemical steps (C), the majority of the voltammetric responses are EC mechanisms of various types.

For B1, B6, B7, and B9, the reduction of the vitamin is a simple electron transfer, E. Vitamin K voltammetry is EE.

Vitamins B1, B9, B5, B6, and E can be reduced and oxidized. Disproportionation of the reduced and oxidized forms can regenerate the initial vitamin species.

Vitamin C has a formal potential near the middle of the water window and undergoes ring opening on oxidation in an ECirrev process. With the lowest E0' for oxidation of a vitamin, vitamin C may serve to reduce superoxide, peroxyl, and hydroxyl radicals and thus mitigate effects of ROS.

The thermodynamic (E0') and mechanistic (EC) characteristics of the 13 vitamins will be surveyed from the perspective of a potential axis to highlight the similarities and distinctions of these 13 electroactive and metabolically critical species.
Reference
[1] M. D. Lovander, J. D. Lyon, D. L. Parr IV, J. Wang, B. Parke, and J. Leddy, CRES3T Review—Electrochemical Properties of 13 Vitamins: A Critical Review and Assessment, Journal of The Electrochemical Society, 165 (2) G18-G49 (2018).
Figure 1. Potential Axis with 13 Vitamins. From reference [1].

Figure 1
MS and EIS Characterization of Electrolessly Deposited Composite Metals on Carbon Fiber Surfaces
Authors: Nelson Ruben , Watson Venroy George , Kannan Dhevathi , Weetom Matthew , Weatherspoon Mark H , Kalu Egwu Eric 
Published: February 2020

Metal deposited carbon cloth electrodes and metal-oxide spinel containing carbon cloth electrodes have shown in past studies to be promising components in energy storage devices [1] [2]. However, the focus is usually on the fabrication procedure that includes an oxidation step and a subsequent two-electrode characterization test in an energy storage test device. The latter may conflate with or be dependent on the stability of other components, such as the electrolyte, the counter electrode, and any other surface reactions. In this study, nickel-molybdenum and copper-tin deposited carbon cloths are fabricated and arranged in a three-electrode setup to determine conductor, semi-conductor, and electrochemical characteristics, specifically their Mott-Schottky and impedance properties, with a follow-up surface characterization by means of scanning electron microscopy. These results are to be compared to characterization results from oxide containing spinels deposited on carbon cloth electrodes fabricated in previous studies [1] [2] [3]. The results of this study intend to provide comparable information that may demonstrate the viability of electroless deposition of metals on conductive carbon as a catalytic support material without the use of an oxidation step to form oxides.
References

R. Nelson, J. Kosivi, M. H. Weatherspoon, E. E. Kalu, J. P. Zheng, Impedance behavior of binderless Ni-Mo composite oxide cathode for a Li-O2 battery via impedance spectroscopy, ECS Trans.,58 (2014).

V. G. Watson, Z. D. Haynes, W. Telama, Y. D. Yeboah, M. H. Weatherspoon, J. P. Zheng, E. E. Kalu, Electrochemical performance of heat treated SnO2–SnCu@C-Felt anode materials for lithium ion batteries, Surfaces and Interfaces, 13 (2018).

Ayman S. ELmezayyen, Shian Guan, Fikry M. Reicha, Ibrahim M. El-Sherbiny, Jianming Zheng, Chunye Xu, Effect of conductive substrate (working electrode) on the morphology of electrodeposited Cu2O, J. Phys. D: Appl. Phys., 48 (2015).

Figure 1
Polyaniline-Modified Hydrolyzed Polyethylene Separators for High-Performance Lithium-Sulfur Batteries
Authors: Tubtimkuna Suchakree , Wutthiprom Juthaporn , Chiochan Poramane , Duangdangchote Salatan , Krittayavathananon Atiweena , Sawangphruk Montree 
Published: February 2020

The practical application of lithium-sulfur battery (LSB) is limited owing to its poor cycling stability stemming from the ‘shuttle effect’ or the migration of soluble polysulfide intermediates (Li2Sn, 4 ≤ n ≤ 8). Numerous strategies have been proposed to solve this issue by designing host materials to control polysulfides within the cathode, developing electrolytes to be able to reduce polysulfide solubility, and adding interlayers to block polysulfide migration to the anode.[1] However, these concepts are far from practical operation. Herein, we introduce the modified polyethylene separator with an objective for reducing the ‘shuttle effect’. The commercial hydrolyzed polyethylene (HyPE) separator was firstly functionalized with carboxylic acid (-COOH) groups before grafting polyaniline (PANI) molecules on its surface via an amide coupling process for which the -COOH on the HyPE surface can chemically react with imine groups (-N=) of the PANI structure. Interestingly, the battery with the modified PANI separator can enhance the specific capacity and coulombic efficiency for 10 and 15%, respectively, as compared with the conventional cell configuration using the PE seperator. Owing to the chemical interaction between the imine group of the quinoid ring in the structure of PANI and the lithium polysulfide molecules, the polysulfide species are retained on the PANI/HyPE surface until Li2S is fully formed.[2] This idea can improve the sulfur utilization and enhance the stability of the lithium-sulfur batteries.
References:

Yin, L., et al., A functional interlayer as a polysulfides blocking layer for high-performance lithium–sulfur batteries. New Journal of Chemistry, 2018. 42(2): p. 1431-1436.

Zhong, M.-e., et al., Accelerated polysulfide redox kinetics revealed by ternary sandwich-type S@Co/N-doped carbon nanosheet for high-performance lithium-sulfur batteries. Carbon, 2018. 128: p. 86-96.

Figure 1
CNF/S Cathodes for RT Na-S Batteries in Carbonate Electrolyte: Understanding the Role of Sulfur Phase and Solid Electrolyte Interphase
Authors: Pai Rahul , Singh Arvinder , Rafie Ayda , Kalra Vibha 
Published: February 2020

Over the last few years, there is growing interest towards safe and stable room temperature sodium-sulfur batteries owing to their high theoretical capacity and energy density of ~1672 mAh/g and 1230 Wh/kg respectively based on the final discharge product of Na2S. However, these Na-S batteries exhibit poor cycling properties mainly due to severe shuttle effect. Sulfur cathodes with various nanostructured carbon have been introduced to achieve long-term cycling. However, that these advances are partially due to the use of a non-carbonate solvent-based ethereal electrolytes, and the additive NaNO3 salt, in which the solubility of polysulfides is reduced or the polysulfide shuttle is passivated. Given the high flammability of ether-based electrolytes, such systems are not practically viable. Moreover, the conversion of sulfur to Na2S/Na2S2 in these reports is unclear.
In this work, we have developed free-standing carbon nanofiber/S cathodes for achieving long-term cycling in RT Na-S batteries. The as-prepared CNF/S (~1.08 mg/cm2, 43.8 wt% S) cathodes were used directly as cathodes in 2032 type coin sized RT Na-S cells. The electrochemical tests were performed in EC/PC/FEC based electrolyte against Na/Na+ anode. The cyclic voltammetry and charge discharge results showed a single potential for conversion of sulfur to Na2S. The CNF/S cathodes delivered capacity of ~1229 mAh/g during the first cycle with ~51.1% coulombic efficiency. The capacity of RT Na-S cells was stabilized at ~350 mAh/g after Ist cycle and sustained up to 300 cycles with only ~.03% decay rate per cycle. The postmortem XRD results confirmed the conversion of sulfur to Na2S and vice versa. Further, we performed in situ electrochemical impedance spectroscopy, postmortem XPS and galvanostatic intermittent titration technique (GITT) to understand the underlaying conversion mechanism. The preliminary results showed that the observed single plateau and long term cycling of RT Na-S cells were the convoluted effect of deposited sulfur and stable SEI layer on the cathode side.
#RP and AS have contributed equally
A FE2 Framework for Ionic Transport Modeling in the Electrolyte of a Battery Cell
Authors: Zhuo Mingzhao , Grazioli Davide , Simone Angelo 
Published: February 2020

An electrolyte is an indispensable component in any battery as it saturates the porous structure of battery separator and electrodes to transport ions. The pore size in battery separator and electrodes is usually two to three orders of magnitude smaller than the typical size of a battery cell [1]. It is therefore computationally infeasible to resolve this problem at the microstructural level for a full scale simulation. To obtain the field variable profiles at the battery cell level, we formulate a FE2 framework for the calculation of ionic concentration and electrostatic potential at the macro cell level from computations at the micro pore scale.
The FE2 framework consists of solving governing equations at two (macro and micro) scales and managing the information exchange between them. The macroscale governing equations describe the balance of charge (with the electroneutrality assumption) and the mass conservation of ionic species [2]; the macroscopic electric current and mass flux are obtained from the solution of the microscale boundary value problem, which is defined on a representative volume element (RVE). The microscale governing equations also describe the balance of charge and the mass conservation of ionic species, but the time variation of the ionic concentration is neglected within the microstructural domain due to the small RVE size [3]. The electric current and mass flux at the micro scale are derived from Nernst-Plank's equations and Faraday’s law of electrolysis. The macroscopic variables (ionic concentration and its gradient, and electrostatic potential and its gradient) at each macroscale integration point are transferred to the microscale problem as boundary conditions, while the averaged current and mass flux are transferred back for the macroscopic computation.
The current FE2 framework can be used to calculate effective transport properties of porous battery separator and electrodes, especially when the microstructure changes in time and space. Moreover, it will be extended to a multiscale simulation of a full battery cell that will allow the prediction of the battery electrochemical performance and in turn provide practical guidelines for battery microstructure design.
References
[1] A. Salvadori et al., International Journal of Solids and Structures, 2015; 59: 90–109.
[2] D. Grazioli et al., Electrochimica Acta, https://doi.org/10.1016/j.electacta.2018.07.234.
[3] I. Özdemir et al., International Journal for Numerical Methods in Engineering, 2008; 73:185–204.
(Invited) Structure and Dynamics in Ion-Conducting Polymers from MD Simulations
Authors: Frischknecht Amalie L. 
Published: February 2020

Simulations of ion transport in ion-conducting polymers such as ionomers are challenging because dynamical processes relevant to the ion transport occur across many orders of magnitude in time. Additionally, designing improved ionomers requires an understanding of how both polymer architecture and ionomer morphology affect ion dynamics. To build a better understanding of the relationships among ionomer chemistry, morphology, and ion transport, we have performed a series of molecular dynamics simulations and connected aspects of these simulations with experiment. In this talk I will describe our recent results on two different ionic polymers. The first is a series of precise poly(ethylene-co-acrylic acid) ionomers, which have acid groups precisely spaced along the polymer backbone. These ionomers form nanoscale ionic aggregates with morphologies dependent on the spacer length between acid groups on the polymer backbone and on mobile ion concentration. Recent atomistic MD simulations of these ionomers are in good agreement with quasi-elastic neutron scattering data at short time scales. The comparison with experiment validates the dynamics in the simulations, which we then use to probe ion dynamics at longer time scales. We also performed coarse-grained simulations to provide insight into ion transport mechanisms at longer times. The second system is a sulfonated poly(phenylene), which conducts protons when hydrated. Atomistic simulations of the structure are in good agreement with NMR spin diffusion measurements of domain sizes and with X-ray scattering. At low sulfonation and hydration levels, clusters are more elongated in shape and poorly connected throughout the system. As the degree of sulfonation and water content are increased, the clusters became more spherical, and a fully percolated ionic domain is formed. I will discuss the connections among the hydrophilic domain morphology, the state of the hydrogen bonding network, and the conductivity in these polymers.
Sandia National Laboratories is a multi-mission 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.

Figure 1
Molecular Dynamics Simulations of Lithium Ion Battery Anode Interface in Battery Charging Process
Authors: Aoyagi Koutarou , Otani Minoru 
Published: February 2020

The use of lithium-ion (Li-ion) batteries to power hybrid, plug-in hybrid, and electrical vehicles in recent years calls for greater battery charge rate than their applications in electric devices. These properties are largely caused by the phenomenon in the interface of electrode and electrolyte. For the battery charge rate, the process of Li+ desolvation in the interface and intercalation to graphitic anode are key factors. However, there are various hypotheses about Li+ desolvation and it has still not been clarified. Detailed understanding of the interface can accelerate the development of Li-ion battery. In this work, to gain an understanding of the Li+ desolvation in battery charging process, atomistic molecular dynamics simulations of the electrode/electrolyte interface at a constant voltage were performed.
We utilize a modified version LAMMPS code implemented the novel computational approach to carry out the simulation of the electrolyte in the presence of electrodes and applied voltage. The approach for treating the model of battery interface held at a constant potential, which has necessity to calculate the nonperiodic cell in the surface normal direction, is based on effective screening medium (ESM) method [Otani and Sugino, Phys. Rev. B 73, 115407 (2006)]. The Poisson equation is solved with the help of the green’s function technic. The electrostatic potential V(z) was solved as following equation, V(z) = -∑q
i|z
i-z|/2ε
0
S
0, where ε
0 is the permittivity of vacuum, S
0 is electrode’s surface area, and q
i is the charge of ith atom. If a potential difference V is applied across the two electrodes, then the charges are induced on each electrode surface to be V(z
le) - V(z
re) = V, where z
le is the z of left side electrode surface and z
re is right one.
Prepared simulation model is the box with two edge plane of graphitic electrodes separated by an electrolyte which consists of 1M LiPF6 / ethylene carbonate (EC) / ethyl methyl carbonate (EMC) 30:70. The interelectrode spacing is 8 nm. We confirmed it is enough to describe the Electric double layer (EDL) of each electrodes with utilizing ESM-RISM method [Nishihara and Otani, Phys. Rev. B 96, 115429 (2017)].
To get the interface structure in EDL in short timescale simulation, preliminary runs for 3 ns at 298 K was carried out in the constant NVT ensemble with applied voltage of constant 20 V. After that equilibration runs for 3.8 ns at 298 K were carried out with applied voltage of constant 1 V. Finally production runs which modeling the charging process from 1 V to 4 V was carried.
We discuss about the Li+ desolvation in battery charging process with observing electrolyte dynamics in EDL.

Figure 1
(Invited) The Electronic Structure Underlying Electrochemistry of Two-Dimensional Materials
Authors: Liu Yuanyue 
Published: February 2020

Two dimensional materials have shown great promise in a variety of electrochemical energy conversion and storage applications, and their further developments require an improved understanding of the atomistic mechanisms and effective design principles. I will discuss how the electronic structure of 2D materials controls atoms adsorption, and use this understanding to explain a number of experiments in alkali-metal-ion batteries [1,2] as well as to discover new 2D catalysts for water splitting [3]. I will also discuss important but often-overlooked factors in modeling electrocatalysis of 2D materials: the varying charge and fixed potential [4], highlighting the necessity of including these factors to elucidate the electrochemical mechanism of 2D materials.
[1] Y. Liu et al, Phys. Rev. Lett. 2014, 113, 028304
[2] Y. Liu et al, PNAS 2016, 113, 3735
[3] Y. Liu, J. Wu, K. P. Hackenberg, Nature Energy, 2017, 6, 17127
[4] D. Kim, J. Shi, Y. Liu, JACS, 2018, 140, 9127
CO Site Preference on Copper Surfaces in Electrochemical Environments: Deciphering Voltage and Electrolyte Composition Effects
Authors: Weitzner Stephen Eric , Akhade Sneha A , Varley Joel Basile , Wood Brandon C. , Baker Sarah E , Duoss Eric B 
Published: February 2020

The development of effective electrocatalysts to convert carbon dioxide into value-added products such as methane and ethylene requires a detailed atomistic understanding of the reaction pathway. While it is well known that copper (100) surfaces exhibit a higher selectivity towards ethylene production, both electrochemical and non-electrochemical pathways have been proposed to describe this process. In both cases, the presence of adsorbed CO plays a crucial role and the pathways are observed to be active under different conditions. In this work, we study the role of the electrochemical environment in stabilizing CO across different copper surface sites and evaluate the energy barriers of key steps in the carbon dioxide electroreduction pathway. Using the recently developed Effective Screening Medium – Reference Interaction Site Method (ESM-RISM), we provide a detailed assessment of the roles of both applied voltages and electrolyte composition effects. Our results demonstrate that these two factors are synergistic, leading to behavior that qualitatively deviates from conventional models.
This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Preparation of Carbon Metal Oxide Composites for Hybrid Supercapacitor Applications
Authors: Malekpour Soheil , Balkus Kenneth J. , Ferraris John P. 
Published: February 2020

Hybrid supercapacitors made of carbon – metal oxide composites are devices which can combine the advantages of both electric double layer capacitors and pseudocapacitors e.g. high energy density, high power density and high cyclibilty. Although there are many ways to make carbon – metal oxide composites, carbon nanofibers (CNFs) as high surface area carbon materials were used as matrix to host the metal oxides. Covering the carbon with metal oxides will cause a decrease in conductivity of the carbon material, hence encapsulating the metal oxides with CNFs is a way for achieving high performance system. It has been shown that blending two immiscible polymers at certain ratios, electrospinning and carbonizing them will lead to formation of carbon, in which the metal oxides can be placed.
Polyacrylonitrile (PAN) as the carbon source and polymethacrylic acid (PMAA) as both metal oxide precursor carrier and in-situ porogen were blended at 1:1 ratio and electrospun. Upon annealing PMAA degraded and left pores. Adding a metal precursor to the blend solution cause interaction of metal with PMAA, hence upon degradation of PMAA, metal oxides were left in the carbon fibers. The prepared carbon – metal oxide composites not only preserves the conductivity of carbon but also adds the pseudocapacitance of metal oxides to the system which leads to a material with enhanced performance. It is predicted to load higher amounts of metal oxides using PMAA compared to conventional metal oxide carriers such as polymethyl methacrylate (PMMA), due to carboxylic groups on PMAA backbone.