bluuebunny/crossref_metadata_2025 huggingface dataset:
Insights into Nanoarchitectual Structures to Enhance the Catalysis Properties of Human Liver Microsomes
Authors: Moulton James Thomas , Premaratne Gayan , Niroula Jinesh , Krishnan Sadagopan
Published: February 2020

Building a nanoarchitectual structure using 1-Pyrenylbutylamine and functionalized multiwalled carbon nanotubes (MWNT) will create an abundance of aminated sites on an electrode for electrostatic interactions binding Human Liver Microsomes (HLM). This increase in secondary interactions will allow for a higher concentration of HLM to bind to the electrode creating a higher catalytic current and increased stability of the bioprocesses involved. Using inexpensive HLM on this nanostructure with applied potential, without NADPH as an electron source, could prove to be a viable bioreactor for swift drug metabolism and inhibition assays. Using cyclic voltammetry the research confirms that High Purity Graphite (HPG) electrodes structured with aminated MWNTs in conjunction with pi-pi stacking of 1-Pyrenylbutylamine with adsorbed HLM increases the catalytic current over 4x that of HLM directly adsorbed on HPG. This nanostructural design demonstrates an almost 2x higher catalytic current using HLM over costly recombinant created CYP enzymes. The formal potential of -0.46 indicates that the CYP reductase is functioning in the HLM and the first to receive the electron transfer as published previously in this lab with recombinant enzymes. Long term impedances stability tests demonstrate that the carbon electrode with this nanostructure is more stable than a costly gold electrode. Using HPLC to measure the hydroxylation of diclofenac to 4’-hydroxydiclofenac HLM outperforms the recombinant enzymes also. Inhibition of the CYP2C9 enzyme in HLM by the competitive inhibitor sulphenazole shown by HPLC indicates that CYP2C9 is responsible for the reduction of diclofenac. This nanostructure design makes improvements over the plain electrode, and could prove to be a feasible method upon to build an inexpensive platform to examine newly developing drugs.
Understanding Charge-Transfer and Kinetic Processes in Particulate Photoelectrode Morphologies for Solar Water Splitting
Authors: Bala Chandran Rohini
Published: February 2020

Z-scheme semiconductor particles, either as suspended solids in an aqueous solution1–3 with soluble redox shuttles, or as particulate sheets4,5 with solid-state electronic contacts, is a promising two-step approach to use solar energy to split water to produce hydrogen and oxygen. For Z-scheme particles to operate efficiently, it is important to realize efficient electron-transfer from the oxygen evolution particle to the hydrogen evolution particle, and to selectively drive the reactions of interest at the semiconductor-electrolyte interface. I will present on the development of a numerical modeling framework to evaluate the transport and kinetics of photogenerated charge-carriers inside a spherical semiconductor particle and across the semiconductor–electrolyte interface for Z-scheme systems with and without soluble redox shuttles. The boundary conditions applied at the electron-transfer interfaces are formulated to take into account all plausible particle surface-mediated redox reactions. The model is used to elucidate the impacts of particle size, recombination pathways, kinetic parameters and the electrochemical potential of the redox species on the performance of these particles. Results are further interpreted to identify strategies to boost the energy conversion efficiency and quantify the influence of the electrode morphologies on the overall rates of hydrogen production in Z-scheme solar water splitting systems.

References

Fabian, D. M. et al. Particle suspension reactors and materials for solar-driven water splitting. Energy Environ. Sci.
8, 2825–2850 (2015).

Bala Chandran, R., Breen, S., Shao, Y., Ardo, S. & Weber, A. Z. Evaluating particle-suspension reactor designs for Z-scheme solar water splitting via transport and kinetic modeling. Energy Environ. Sci.
11, 115–135 (2018).

Keene, S., Bala Chandran, R. & Ardo, S. Calculations of theoretical efficiencies for electrochemically-mediated tandem solar water splitting as a function of bandgap energies and redox shuttle potential. Energy Environ. Sci. (2019). doi:10.1039/C8EE01828F

Chen, S., Takata, T. & Domen, K. Particulate photocatalysts for overall water splitting. Nat. Rev. Mater.
2, 17050 (2017).

Goto, Y. et al. A Particulate Photocatalyst Water-Splitting Panel for Large-Scale Solar Hydrogen Generation. Joule
0, (2018).

Figure 1
Development of PANI/Chitosan/Ionic Liquid/Gce Based Sensor for the Simultaneous Electrochemical Quantification of Pharmaceuticals
Authors: Jadon Nimsha
Published: February 2020

A simple and sensitive method for simultaneous determination of pharmaceuticals viz Domperidone (DMP) and Pantoprazole (PTZ) has been developed on PANI/CS/IL/GCE sensor. The Prepared sensor was characterized by Scanning Electron Microscopy (SEM) and Electrochemical Impedance Spectroscopy (EIS). The voltammetric measurements were carried out using square wave voltammetry and cyclic voltammetry. The modified sensor shows a good catalytic response towards the reduction of DMP and PTZ with a well-defined with reduction peaks at -0.7 V and -1.17 V in Britton-/Robinson buffer at pH 4.3.Variation in the peak signal with solution variables such as pH and concentration of drugs and instrumental parameters like deposition time and potential, frequency and amplitude has also been studied. The modified sensor shows a good linear calibration curve for DMP and PTZ over a concentration range with a lower detection limit of 25.1 ng/mL and 22.5 ng/mL respectively. The developed sensor was competent to determine both drug effectively without any interference.The analytical application of the sensor have been confirmed by determining the DOM and PTZ in human fluids and pharmaceutical samples. Suitability of developed sensor in clinical diagnosis was found with high sensitivity, good selectivity and reproducibility.
(Invited) Confocal Raman Microscopy in the Study of Membrane Materials for Energy Conversion
Authors: Korzeniewski Carol , Cai Rong , Kitt Jay , Liang Ying , Minteer Shelley D. , Harris Joel M.
Published: February 2020

Confocal Raman microscopy techniques are being adapted for quantitation, structural characterization and spatial profiling in the development of materials for electrochemical energy conversion. This presentation will discuss applications to fuel cell catalytic membranes and bipolar membranes and strategies for estimation of the limiting spatial resolution in depth profiling.1,2

In the study of catalytic membranes, experiments have focused on steps in the processing of electrodes containing biocatalyst. Confocal Raman microscope measurements confirm the presence of entrapped enzymes within dispersion cast membranes and enable charge compensating mobile ions and protein to be quantified. For the enzyme laccase, a common biofuel cell O2reduction catalyst, features associated with ligands coordinating the T1 copper center are present between 400 cm-1- 500 cm-1 and provide a possible route to interrogate mechanistic chemistry at the active site of laccase biocathodes under fuel cell reaction conditions. Using a similar experimental approach, the junction connecting the anion exchange and cation exchange phases of a bipolar membrane was spatially profiled. The transition region separating the phases was broader than the limiting axial spatial resolution of the instrument, consistent with known roughness and inhomogeneity at the boundary on the order of a few micrometers. Strong Raman scattering from perchlorate enabled its use as a probe for mobile ions in the anion-exchange phase. Self-modeling curve resolution applied to spectral datasets within a depth profile enhanced spatial resolution and confirmed perchlorate ions track the spatial distribution of the AEM phase.

1Cai, R.; Abdellaouia, S.; Kitt, J.P.; Harris, J.M.; Minteer, S.D.; Korzeniewski, C. “Confocal Raman Microscopy for the Determination of Protein and Quaternary Ammonium Ion Loadings in Biocatalytic Membranes for Electrochemical Energy Conversion and Storage” Anal. Chem.(2017) 89, 13290-13298. DOI: 10.1021/acs.analchem.7b03380.

2Korzeniewski, C.; Kitt, J.P.; Bukola, S.; Creager, S.E.; Minteer, S.D.; Harris, J.M. ”Single layer graphene for estimation of axial spatial resolution in confocal Raman microscopy depth profiling” Anal. Chem. (DOI:DOI: 10.1021/acs.analchem.8b04390).
(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
Solvent Effects on Nafion Dispersion Structure Probed By Infrared Spectroscopy
Authors: Liang Ying , Korzeniewski Carol
Published: February 2020

The structure of Nafion dispersed in water and ethanol solutions was investigated using infrared spectroscopy. Since the properties of dispersing fluids can affect the mechanical strength of solution-cast Nafion thin films,1 it was of interest to gain insights into the structure and the vibrational spectral properties of the ionomer in the dispersion phase. To minimize deleterious effects of optical dispersion,2 traditional transmission infrared spectra were recorded from both dispersions as well as solvent-free thin films. Subsequently, transitions from the dispersion, through the gel-phase and dried film were followed as a function of time during film formation using the attenuated total reflection (ATR) infrared sampling technique. The vibrational spectra of thin Nafion films prepared from dispersions in ethanol solvent and water solvent were similar, except the former had a pronounced shoulder near 1125 cm-1 and sharper 983 cm-1 peak, both of which can be ascribed to sidechain vibrations. The enrichment of trace water in the ethanol solvent during evaporative drying was quantified through analysis of the 2750 cm-1 – 3500 cm-1 spectral region using partial least square (PLS) modeling. In the gel-phase, water was detected above 50 mol%, indicating water enrichment should be considered in developing models for solvent effects on Nafion film formation.

Kim, Y. S.; Welch, C. F.; Hjelm, R. P.; Mack, N. H.; Labouriau, A.; Orler, E. B. Origin of toughness in dispersion-cast Nafion membranes Macromolecules
2015, 48, 2161-2172.

Kollath, V. O.; Liang, Y.; Mayer, F. D.; Ma, X.; Korzeniewski, C.; Karan, K. Model-based analyses of confined polymer electrolyte nanothin films experimentally probed by polarized ATR−FTIR spectroscopy J. Phys. Chem. C
2018, 122, 9578−9585.

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
Electrospun Ca2Fe2O5 Nanofibers As Anode for Next Generation Li Ion Batteries
Authors: Sundriyal Sandeep Kumar , Sharma Yogesh
Published: February 2020

Development of advanced anode materials with exceptional storage performance is essential for next generation Li ion batteries (LIBs). The morphological architectures of electrode materials play a vital role in enhancing the storage performance of any materials. In this study, nanofibers of Ca2Fe2O5 (C2FO) have been fabricated by simple and cost-effective electrospinning technique, and thoroughly characterized by field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), X-ray diffractometer (XRD), X-ray photoelectron spectroscopy (XPS) and Brunauer–Emmett–Teller (BET) surface area analyser. To the best of our knowledge, C2FO nanofibers are employed as LIB anode for the first time. The influence of nano-morphologies on the storage performance of C2FO is investigated by cyclic voltammetry (CV), galvanostatic charge-discharge (GCD) and electrochemical impedance spectroscopy (EIS). C2FO nanofibers exhibit initial reversible capacity of 650(±10) mAh.g-1 and maintained reversible capacity of 600(±10) mAh.g-1 after 100 cycles when cycled at 50 mA g-1
. Further, good rate capability was also observed. Nanoparticles of C2FO were also examined as LIBs anode, however, nanoparticle are found to be inferior to the nanofibers. The better performance of C2FO nanofibers is attributed to 1D nanofibric morphology consisting of interconnected nanoparticle with minimum interparticle resistance that probably facilitate smoother transportation of electrons/ions.

References:

Y. Sharma, N. Sharma, G. V. S. Rao, and B. V. R. Chowdari, Adv. Funct. Mater., 17, 2855 (2007).

J. Bhagwan, V. Sivasankaran, K. L. Yadav, and Y. Sharma, J. Power Sources, 327, 29 (2016).

J. Bhagwan, A. Sahoo, K. L. Yadav, and Y. Sharma, J. Alloys and Compd., 703, 86 (2017).

Figure 1
Monoclinic Na2.4V2(PO4)3/Conductive Polymer Composite As High Capacity Cathodes for Na-Ion Batteries
Authors: Lee Yongseok , Park Hyunyoung , Ko Wonseok , Myung Seung-Taek , Kim Jongsoon
Published: February 2020

We report a monoclinic Na2.4V2(PO4)3/poly(3,4-ethylenedioxythiophene) (M-NVP/PEDOT) composite as a novel cathode material for sodium-ion batteries. The active materials were homogenously encapsulated by thin layers of the electro-conductive polymer PEDOT, and X-ray diffraction analysis indicated that the final products were crystallized into a monoclinic structure. The composite exhibited much more outstanding power capability and cyclability than pristine M-NVP. The discharge capacity of the M-NVP/PEDOT electrode was maintained up to ~109.8 mA h g-1 at 10C (1C = ~178 mA g-1), which was ~9 times higher than that of pristine M-NVP under the same conditions. Moreover, whereas severe capacity degradation was observed for pristine M-NVP, the M-NVP/PEDOT composite delivered ~81% capacity retention compared with the initial capacity over ~500 cycles at 1C. In particular, the available capacity of M-NVP/PEDOT was ~143.3 mA h g-1, corresponding to ~2.4 mol Na+ (de)intercalation, which is larger than the reversible capacity of rhombohedral Na3V2(PO4)3, at which only 2 mol Na+ can be (de)intercalated. This unexpectedly high capacity of the M-NVP/PEDOT composite was clearly confirmed through combined studies using several experiments and first-principles calculation.

Figure 1
Three-Dimensional Compositional and Charge Heterogeneities in Sodium Layered Oxide Cathode Materials
Authors: Rahman Muhammad Mominur , Lin Feng
Published: February 2020

Rechargeable energy storage devices have revolutionized the modern electronic industries and electric vehicles. Li-ion batteries with lithium layered oxide cathode materials have mainly dominated the market so far. However, energy storage devices based on sodium layered oxide cathode materials have drawn renewed attention because of the wide availability and cheap sodium resources. These devices are also particularly suitable for some applications such as grid energy storage, which require load leveling and adjusting to intermittent energy production from the renewable energy resources. To date, sodium-ion batteries based on layered oxide cathode materials are far from commercialization because of the low power and energy density as well as low round-trip efficiency because of the bulk phase transformation and surface degradation. Thus, novel design strategies must be undertaken to improve the electrochemical performance of these sodium layered oxide cathode materials. We have designed a highly compositionally heterogeneous Na0.9Cu0.2Fe0.28Mn0.52O2 cathode material for sodium-ion batteries. The material delivers a capacity of 125 mAh/g at C/10 with no capacity fading after 100 cycles and 75 mAh/g at 1C with negligible capacity fading after 200 cycles. In addition to the compositional heterogeneity, we have further demonstrated the heterogeneous nature of redox chemistry of the cathode material. The surface redox behavior of the transition metals is different than that in the bulk. In the bulk, both Cu2+ and Fe3+ play an active role in the redox chemistry of the cathode material whereas the surface redox chemistry is mainly dominated by Mn4+ ion. Furthermore, we also demonstrate that Mn segregation on long term cycling may play a pivotal role for the performance degradation. Through this study, we demonstrate that there is further room for improvement for sodium layered oxide cathode materials by tuning the nano/mesoscale elemental distribution. Tunable elemental distribution may also enable favorable surface chemistry of cathode materials that can account for the Mn segregation on long term cycling and enhance the cycle life of sodium-ion batteries.
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
Engineering the Low-Temperature Performance of Li-S Batteries
Authors: Gupta Abhay , Manthiram Arumugam
Published: February 2020

For the last few decades, lithium-ion batteries employing insertion-compound cathodes and graphite anodes have become the standard in consumer electronics and have even become commonplace in applications with extreme-operating environments, such as missions to space.1 As such missions increase in complexity and applications continue to require increasingly greater specific energy, the energy density of secondary batteries needs to similarly increase. Lithium-sulfur (Li-S) batteries have the potential to offer significant improvements due to the sulfur cathode’s high theoretical capacity of 1,672 mA h g-1 and system’s theoretical energy density of 2,500 W h kg-1.2

Conventional lithium-ion batteries experience a sharp loss in energy and power density at temperatures below 0˚C, which significantly impacts design parameters for applications like space missions. During charge and discharge, low temperatures kinetically impede all steps of mass transfer of lithium ions through the battery, particularly through the increasingly viscous electrolyte as well as the electrode-electrolyte interface. This ultimately leads to reduced capacity and utilization of active material.3 In this work, we show that many of these same trends hold true for Li-S batteries at low temperatures. Not only is there a severe drop in accessible capacity with decreasing temperatures, but this loss is primarily exhibited by a shortening in length of the second voltage plateau.4 This plateau corresponds to the formation of the insoluble Li2S discharge product, and from the low temperature behavior, we see that the nucleation and growth of this species is a primary kinetically limiting barrier to low temperature operation of Li-S cells. This presents opportunities for investigation into the kinetic behavior of sulfur reduction and the dynamic interplay between soluble and insoluble species in nonaqueous solvents at low temperatures. We explore this behavior in detail and discuss our efforts in electrolyte co-solvent and additive engineering towards designing a Li-S battery capable of operating at low temperatures.

Acknowledgement: This work was supported by a NASA Space Technology Research Fellowship.

References:

M. C. Smart, B. L. Lucht, S. Dalavi, F. C. Krause, and B. V Ratnakumar, J. Electrochem. Soc., 159, 739–751 (2012).

S.-H. Chung, C.-H. Chang, and A. Manthiram, Adv. Funct. Mater., 28, 1801188 (2018).

G. Zhu et al., J. Power Sources, 300, 29–40 (2015).

Y. V Mikhaylik and J. R. Akridge, J. Electrochem. Soc. , 150, A306–A311 (2003).

Figure Caption:

Figure 1. Third cycle discharge-charge curves of a standard Li-S cell at room temperature, 0° C, and -20° C.

Figure 1
The Magnesium-Sulfur Battery with High Rate and Improved Capacity Using Cu Nanoparticle Additives
Authors: He Peng , Ford Hunter O. , Merrill Laura C. , Schaefer Jennifer L.
Published: February 2020

The metallic Mg anode has a very high theoretical volumetric capacity of 3832 mAh/cm3, in comparison to 2062 mAh/cm3 for Li. Moreover, Mg has widespread natural abundance and is of lower cost. Sulfur is also a cheap and safe material which can be used as cathode for Mg batteries. However, the Mg/S battery has several disadvantages which block its practical application. One of these challenges is the polysulfide shuttle effect which is common in metal-sulfur batteries and results in decreased coulombic efficiency and battery lifespan. To solve this problem, many inorganic compounds have been used as additives to adsorb polysulfides in the Li/S battery cathode. The same method may also be effective in the Mg/S battery. It has been reported that the Mg/S battery with a Cu current collector is able to cycle for more 25 cycles while using other current collectors, the Mg/S cell has much poorer performance. This result suggests that the Cu-S interaction can influence the performance of Mg/S battery and improve the cycling stability. To study the interaction between Cu and S, Cu nanoparticles are synthesized and mixed with the sulfur cathode. It is found that Cu2S forms on the Cu surface and facilitates the reduction of sulfur in the Mg/S battery. The inclusion of Cu nanoparticles enables the battery to charge/discharge at higher current densities and also improves the cycling stability. The Mg/S battery with Cu additives can run at 0.5 C for more than 50 cycles and deliver a significant capacity.
Bioinspired Electrodes for Structural Supercapacitors
Authors: Flouda Paraskevi , Lagoudas Dimitris , Lutkenhaus Jodie
Published: February 2020

The demand for efficient energy storage devices has increased tremendously as hybrid vehicles, portable, and even wearable electronics have become a significant and inseparable part of our everyday lives. With respect to the increasing demands for energy storage, new battery and supercapacitor technologies have emerged. However, their high weight and size remain a drag on the development of next-generation electronics. Structural energy storage devices constitute a firm solution since they can potentially address both energy storage and structural functionalities in a single unit leading to mass and volume savings. Here, we utilize the ‘brick and mortar’ structure of nacre to fabricate mechanically strong supercapacitor electrodes. We report on electrodes consisting of branched aramid nanofibers (BANFs) and reduced dopamine functionalized graphene oxide (rGO-DOPA). Branched aramid nanofibers, nanoscale Kevlar® fibers, are promising due to their superior mechanical properties, such as stiffness and tensile strength. Furthermore, rGO is an ideal material for supercapacitor electrodes due to its high surface area and electrical conductivity. Graphene oxide was functionalized with dopamine - a molecule mimicking the highly adhesive mussel proteins - to improve interfacial interactions. The electrodes were fabricated using vacuum filtration, where BANFs interact with GO-DOPA through extensive hydrogen bonding and π-π stacking interactions. Coordination bonding was also achieved by the addition of calcium ions that cause chelation. The electrodes were characterized using scanning electron microscopy (SEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). We studied the effect of dopamine functionalization, calcium ion addition and BANF composition on the mechanical and electrochemical performance. Tensile testing, cyclic voltammetry, and galvanostatic charge-discharge were used to evaluate the properties.
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
Effects of Particle Sizes of Active Materials and Conductive Additive on the Electrochemical Performance of a Semi-Solid Flow Battery
Authors: Liu Baichen , Chen Tao , Sun Jie , Zheng Menglian
Published: February 2020

The semi-solid flow battery is one of the promising energy storage technologies in the future energy systems, especially for the applications that require high energy densities. Compared to the other redox flow batteries, the semi-solid flow battery provides a higher solubility of active material and relatively higher voltage window by employing the suspension of active lithium materials and conductive additive, which can offer around 5-20 times greater volumetric capacity. In this regard, its energy density is no longer limited by the solubility, but rather the allowed fraction of active lithium material solids in the flowable suspension. Some previous studies have attempted to optimize the proportion of active lithium material solids and conductive additive to balance the trade-off between the conductivity and viscosity of the suspension. However, few of them considered the influence of the particle sizes of the active lithium materials and conductive additive. Considering that the particle sizes can have significant impacts on the percolated conductive network and rheological properties of the electrolyte suspension, their effects on the performance of the semi-solid flow battery are explored in the present study. Specifically, different particle sizes of active lithium materials and conductive additive are prepared, respectively, based on the LiNi0.8Co0.1Mn0.1O2 (LNCM)-based suspensions for the semi-solid flow battery. The resistance and electrochemical performance, as well as the rheological properties are investigated through single-cell experiments. Furthermore, the stabilities of the suspension with varying particle sizes are also investigated in the present study.
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
(Keynote) Nuclear and Electronic Quantum Effects in the Chemical Dynamics of Proton Defects in Hydrogen-Bonded Liquids
Authors: Markland Thomas Edward
Published: February 2020

Proton defects in hydrogen bonded liquids exhibit a variety of complex structural and dynamical features ranging from rapid diffusion to broad spectral features and perturbed reactivity at interfaces. Accurately describing the chemical dynamics of proton defects requires the ability to simultaneously treat the quantum mechanical nature of the electrons, to describe the constant breaking and forming of chemical bonds, and the nuclei, to include the large zero point energy of the light hydrogen atoms. In this talk I will discuss our recent developments that allow for the efficient quantum mechanical treatment of the electrons and nuclei which now enable us to perform such simulations 100’s of times faster than was previously possible. I will then show how these advances can be used to elucidate transport mechanisms and spectroscopic features of these defects in aqueous and non-aqueous hydrogen bonded liquids in bulk and interfacial environments.
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.