bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study on the Decontamination Possibility of Simulated Radioactive Inconel 600 – Co Alloy Using Electrorefining in LiCl-KCl Electrolyte
Authors: Choi Woo-Seok , Lee Young-Jun , Lee Seong-Hun , Lee Jong-Hyeon
Published: February 2020

As the operating period of a nuclear power plant increases, the demand for dismantling of nuclear facilities has been rising, and the dismantling market is expected to continue to expand steadily. The Inconel 600, which was used as a material for the steam generator, has problem with crack and corrosion, and it is currently replaced with a steam generator of Inconel 690. It has been reported that if this steam generator is corroded or cracked, the cooling water contaminated with radioactive elements such as cobalt, strontium, may penetrate into the cracks. Therefore, development of decontamination technology for radioactive metal waste is essential to minimize waste during dismantling process.

This study investigates the decontamination possibility of Inconel 600 in LiCl-KCl-CoCl2-NiCl2 molten salt electrolyte. Inconel 600 – cobalt alloy was used for anode as a simulated radioactive metal waste. After electrorefining process, the cobalt remains in the molten salt. Therefore, CoCl2 was added to the electrolyte to imitate the case when the radioactive metal waste was dissolved and concentrated in the electrolyte. Electrochemical analysis was performed by cyclic voltammetry (CV) to confirm the redox behavior of Ni ions in molten salt electrolytes. Decontamination experiments were performed by chrono potentiometry (CP) to analyze the oxidation behavior of Inconel 600 – cobalt alloy (anode) and the reduction behavior of Ni on Ni plate electrodes (cathode). Decontamination factor(DF) of the deposits produced by electrorefining was analyzed by ICP.
Fabrication of Silicon Quantum Dots from Silicon Nanowires by a Combined Process of Chemical Etching and Ultrasonication
Authors: Alice Francis Aneeta , Mohan Susmitha , Koech Philemon K , Ogini Martins E , Deo Makarand , Albin Sacharia
Published: February 2020

Silicon quantum dots (SiQDs) have special optical and electronic properties such as bright emission, size-dependent and wavelength-tunable luminescence, broad excitation spectra, and photostability that are rarely found in bulk substrate. Current approaches such as CVD, and laser pyrolysis to produce SiQDs involve complex equipment in combination with harsh chemicals. Here we present a simple and novel technique for conversion of silicon nanowires (SiNWs) to SiQDs. The method combines single step metal assisted chemical etching (MACE), ultrasonication and post chemical etching. Using AgNO3/HF solution, uniform SiNWs were produced by MACE for one hour to obtain a reduced reflectance of 1%. The SiNWs were harvested from the substrate by using ultrasonication and showed an average length of 1.5 um, ascertained from SEM images. Sonication for a fixed duration resulted in conversion of wires into silicon nanoparticles (SiNPs) with diameter varying from 30 to 710 nm. By controlling the time as well as the power of ultrasonication, smaller and uniform SiNPs can be produced. Subsequently, the SiNPs were subjected to a controlled chemical etching in a mixture of HF and H2SO4 to reduce the size further down to less than 10 nm. Here the etch rate and termination of etching are significant factors in determining the dimension of QDs and thereby their emission wavelength. This step enables the stability of photoluminescence of SiNPs by converting them to H-terminated SiNPs. As the etching proceeded, solution color changed from brown to yellow indicating a preliminary result for size reduction. The quantum confinement effect will be verified using photoluminescence as SiQDs emit blue-shifted photons when the size reduces to about 4 nm. The effects of ultrasonication time and power, and the controlled chemical etching on the emission properties of SiQDs will be presented.
Time-Resolved Single-Cell Lysis Kinetics of Metal Nanoparticle-Infused Biopolymer Matrices
Authors: Danhausen Dany M , Beckmann Thomas J. , Keleher Jason J.
Published: February 2020

Bacterial infections continue to be a growing concern in healthcare facilities due to the increasing number of multi-drug resistant bacteria. The extensive use of antibiotics has weakened the potency and effectiveness of these drugs, consequently promoting bacterial infections and extending healing time. Therefore, there is an immediate demand to find an alternate method to combat the spread of bacterial infections. Metal nanoparticles (MNP) have proven to be an effective antibacterial agent against antibiotic-resistant bacteria, and when incorporated into polymeric substrates, have exhibited high toxicity towards bacterial cells. Current research proposes that MNP interact with the bacterial cell wall, undergo redox processes to form ions, and the ions diffuse into the cell resulting in disruption of membrane-bound proteins. This results in the inhibition of cell replication or cell lysis. However, existing methods of antimicrobial susceptibility testing, such as broth dilution assays and disk diffusion, fail to provide a greater understanding of the time scale required for the single cell lysis process to occur. More specifically, the conventional methods have substrate and agent limitations, as well as assume homogeneity in the bacterial population, therefore making the techniques an ineffective method for probing the cell lysis mechanism of MNP-infused biopolymer matrices. To further investigate the mechanistic action of metal nanocomposites, this research utilizes epi-fluorescence optical tweezers for antibacterial characterization. More specifically, a single E. coli cell was optically trapped, non-covalently docked to MNP-infused alginate matrix, and the cell viability kinetics were monitored in situ. Initial results showed that antibacterial activity of Cu and Ag functionalized nanocomposites was related to the metal concentration and size of colloidal NP. Ag incorporated polymers exhibited greater antibacterial effectiveness when compared to Cu potentially due to the role of Cu in cellular respiration processes. Results further indicate that the size of the MNP does impact the rate of single cell lysis, which may be related to the redox kinetics at the cell/MNP interface.
Electrochemical Detection of Endocrine Disruptor (Bisphenol Compounds) in the Consumer Applications
Authors: Tom Robinson , Varman Arul Mozhy , Soundappan Thiagarajan
Published: February 2020

Bisphenol A known as BPA is a chemical compound which used to strengthen various plastic products. BPA is well known endocrine disruptor and continuous adulteration of BPA through various resources will result in type-II diabetes in human being. Therefore, it is essential and important to measure endocrine disruptors known as hormone disruptors, which increase the risk of diabetes, and cancer in human being. The chemical capability of BPA also alters, affects brain chemistry, behavior, reproductive systems, and prostate glands in fetuses, infants, and in children. About 90% of us accumulate BPA levels through food containers, baby feeding bottles, thermal printing papers, and from the water bottles. In 2010 the toxicity levels revealed the importance of removing of BPA from the plastic products such as baby feeding bottles, baby formula bottles, pacifiers, canned foods, and in the inner lining of beverages. Therefore, it is important to detect and determine the toxicity levels of BPA in the commercial products. Herein, we report the electrochemical detection of BP compounds based on modified/pretreated electrodes at lab scale. We have detected and determined the BP concentrations in the physiological pH conditions using these electrodes. Further the sensitivity, selectivity, and linear range of these electrodes falls within the range to fabricate real time electrodes to sense BP contamination in the real-time applications.

Acknowledgment:

The research work presented herein is financially supported by USDA-NIFA
Simultaneous SECM-AFM-Ters Mapping of Electrocatalytic Reactions on a Nanometric Scale
Authors: Schechter Alex , Subramanian Palaniappan , Kolagatla Srikanth
Published: February 2020

We have developed and used Scanning Electrochemical Microscopy-Atomic Force Microscopy (SECM-AFM) imaging technique that can provide high resolution detailed electrochemical and spectral information of oxygen reduction reaction (ORR) reaction at a lateral resolution of less than 50 nm. The ORR activity of an individual unsupported Pt nanoparticle, carbon-supported Pt aggregates and Fe, N surface modified graphitic carbon was mapped under selected reduction conditions. This newly developed method utilizes a gold coated SiO2 tip imbedding a 50 nm diameter Pt electrode. positioned at a constant working distance of ~4-8 nm above the catalyst surface using force feedback control. A 532 nm Raman laser directed to the apex of the tip was applied to collect tip enhanced Raman spectral (TERS) signal of the reaction byproduct (H2O2). Thus, we simultaneously mapped the electrochemical oxygen reduction by the Pt tip electrode and measured the H2O2 oxidation currents on the gold coating secondary electrode and at the same time reordered the peroxide tip enhanced Raman signal under the same scanned area. A direct evidence was seen, showing for the first time that the same active ORR sites are also responsible for peroxide formation (figure 1). Moreover, on a nanometric level ORR proceed mostly via 2 electron reaction to hydrogen peroxide rather than the literature reported 4 electrons reduction of O2 to water, as widely accepted from other electrochemical techniques.

Fig. 1. Nanoscale Mapping of Catalytic Hotspots on Fe, N -modified HOPG by Scanning Electrochemical Microscopy-Atomic Force Microscopy [1].

[1] Srikanth Kolagatla, Palaniappan Subramanian and Alex Schechter*, Nanoscale, 2018, 10, 6962

Figure 1
Scanning Electrochemical Cell Microscopy for Analysis of Solid Electrolyte Interface on Negative Electrodes in Lithium-Ion Batteries
Authors: Kumatani Akichika , Sato Yuto , Takahashi Yasufumi , Shiku Hitoshi , Matsue Tomokazu
Published: February 2020

Lithium-ion battery is one of the most popular secondary batteries for practical applications such as mobile phones and electrical cars because of their high energy density and good cyclability. For further improvement of their total performance with highly efficient cyclability, it is necessary to be in precise control of lithium-ion transport at the interface between electrolyte and electrodes. There is a major issue for efficient ion transport due to solid electrolyte interface (SEI) on negative composite electrodes such as graphite and/or silicon with some binders and electrical additives. The SEI is in general formed by decomposition of electrolyte. However, the SEI formation process or SEI itself is not still clear how the decomposition process proceeds due to the surface structure, binders or dispersion of active materials. Here, in this work we have used a scanning electrochemical microscopy (SECCM) with a single barrel nanopipette inside glove-box for analyzing local electrochemical reaction for SEI formation. A 50 nm radius nanopipette was filled with organic electrolyte (1.0 M LiPF6 in ethylene carbonate:diethyl carbonate = 1:1 in vol. %) with a Li reference electrode. When the pipette was approached to the sample surface, a meniscus was created. Then, through the meniscus as a nanoscale electrochemical simulator, cyclic voltammogram was measured to introduce the SEI in localized area. The location SEI formed and their created potential were mapped by scanning the pipette on the sample. Further, on the particular structure such as basal and edge of graphite, the decomposition process was also analyzed for investigation of material structures for SEI formation. Those information would be particularly important to understand their mechanism and to control SEI formation.
Potentiometric Tip Electrodes for Improved Visualization of Galvanic Corrosion Processes Using SECM
Authors: Filotás Dániel , Fernández-Pérez Bibiana M. , Nagy Lívia , Nagy Géza , Souto Ricardo M.
Published: February 2020

Galvanic corrosion of magnesium is one of the main reasons of the limited usage of this metal. Therefore the galvanic corrosion of magnesium is of great scientific and industrial interest. Among many analytical methods being used, Scanning Electrochemical Microscopy (SECM) has the advantage of chemical surface imaging with high spatial and temporal resolution. When it comes to Mg corrosion, the amperometric mode of SECM is an attractive option although Mg ions cannot be measured directly due to the high negative overvoltage of Mg2+ reduction. Instead, the feedback mode and hydrogen detection in sample generator – tip collector mode are employed [1]. However, H2 oxidation is not a diffusion controlled process and local ion concentrations may affect the oxidation current.

Alternately, SECM can be employed in potentiometric mode. In this case, the sensing probe is an ion selective microelectrode (ISME) which potential is measured against a reference electrode using an operational amplifier-based voltage follower. In this way, direct measurement of Mg2+ distribution has been achieved [2]. However, the occurrence of electric field effects for Mg corroding under galvanic coupling has been demonstrated [3]. Electric cross-talk shifts the measured potentials with respect to the calibration completed in unbiased conditions, resulting in the determination of wrong ion activities.

The work reported here demonstrates the applicability of ion selective electrodes in multibarreled arrangement for simultaneous monitoring of pH and Mg2+ distribution above AZ63 magnesium alloy using SECM. The superior performance of multibarreled tips containing an internal reference electrode compared to “traditional’ single barreled electrodes and double barreled electrodes is shown.

References:

[1] S.S. Jamali, S.E. Moulton, D.E. Tallman, M. Forsyth, J. Weber, G.G. Wallace, Electrochim. Acta 152 (2015) 294.

[2] N.A. Chaniotakis, J.K. Tsagatakis, E.A. Moschou, S.J. West, X. Wen. Anal. Chim. Acta 356 (1997) 105.

[3] A. Kiss, D. Filotás, R. M. Souto, G. Nagy, Electrochem. Commun. 77 (2017) 138.
Photoelectrochemical Microscopy of Ultrathin Liquid Junction Solar Cells
Authors: Sambur Justin , Wang Li
Published: February 2020

Solid state photovoltaic devices made of monolayer two-dimensional (2D) transition metal dichalcogenide (TMDs) monolayers such as WSe2, MoS2, and MoS2/WSe2have achieved 1-3% power conversion efficiency. However, photo-generated charge carriers in the middle of the device typically traverse tens of micrometers toward end-on electrical contacts at the device edge. The long transport distances parallel to the TMD layers give rise to transport-limited device physics that limit overall device performance. Here we demonstrate ultrathin liquid junction photovoltaic systems that use an iodide-based hole-selective electrolyte contact that facilitates a charge transport pathway perpendicular to the 3-atom thick TMD materials. These proof-of-concept indium doped tin oxide (ITO)|monolayer TMD|I–/I2|Pt cells exhibit peak internal quantum efficiencies (IQE) of 7.1%, 34.5%, and 8.2% and open circuit voltages (V
OC) of 0.46 V, 0.26 V, and 0.28 V for WSe2, MoS2, and MoS2/WSe2 heterojunctions. The photocurrent efficiency values are competitive with solid state devices. Surprisingly, we observe a non-linear scaling relation between IQE and layer thickness for homojunction and heterojunction TMDs that can be attributed to either thickness-dependent charge carrier dynamics or a buffer layer screening effect at the ITO/TMD interface. We discuss opportunities to improve the fill factor and V
OCby interface engineering and tuning the energy level offset between the TMD composition and redox electrolyte potential.
Characterizing the Surface Free Energy of Composite Electrodes for Li-Ion Batteries
Authors: Li Jianlin , Davoodabadi Ali , Jin Congrui , Wood David L.
Published: February 2020

One of the crucial steps in battery manufacturing is the electrolyte wetting step which typically requires a relatively long time to be completed. It is known that the relationship between polar and dispersive components of the electrolyte surface tension and the electrode surface free energy (SFE) plays a vital role in the extent of wetting and, thus, tuning the SFE can accelerate the wetting step in battery manufacturing.

This work developed and validated a systematic approach to characterize surface free energy of composite electrodes for lithium-ion batteries, which has never been reported in literature. It’s demonstrated as shown in Figure 1 [1] that the SFE of LiNi0.5Mn0.3Co0.2O2 cathode was higher than the graphite anode. In addition, when switching manufacturing from conventional solvent based processing to aqueous processing, the polar component of SFE increases; it increases 74.1% from NMC532-NMP to NMC532-Water, and 48.2% from A12-NMP to A12-Water due to different binders. SFE decreases with reducing porosity. The results provide valuable guidance for our goal to optimize the electrolyte wetting process, helping lower costs and enable higher product quality. In addition, the method allows us to characterize the SFE of electrodes and optimize electrolyte wetting via tailored electrode manufacturing, including slurry and electrode formulation, mixing sequences, drying protocols and calendering. Figure 1 Surface energy of electrodes Reference:

[1] A. Davoodabadi, J. Li, Y. Liang, R. Wang, H. Zhou, D.L. Wood III, T. J. Singler, and C. Jin, Journal of the Electrochemical Society, 165(11) (2018) A2493-A2501

Figure 1
Battery Characterization Using Operando Optical Diagnostics
Authors: Porter Jason Morgan , Saqib Najmus
Published: February 2020

Battery development is being accelerated by the use of operando characterization tools, which provide real-time measurements of chemistry and transport during battery operation. While much attention has focused on recent advancements in diagnostic tools, such as x-ray spectroscopy and tomography or neutron reflectometry, optical diagnostics continue to provide new insights into battery chemistry and transport. Optical diagnostics, including ultraviolet and infrared absorption spectroscopy, Raman spectroscopy, optical microscopy, and fluorescence, are being used to study complex battery phenomena from dendrite growth and solid electrolyte interface formation to electrolyte stability.

Optical access is a fundamental challenge to using optical characterization in batteries, as electrochemistry necessarily occurs between two conductors, which are opaque to electromagnetic radiation in the UV, visible, and infrared. While transparent conductors have been used in select cases, most optical characterization studies employ custom electrochemical cells with modified battery geometries to allow for optical access (so called “spectro-electrochemical” cells). Spectro-electrochemical cells create unique challenges for operando battery characterization, as the observed trends are necessarily impacted by modifications to battery geometry and materials. The recent commercialization of spectro-electrochemical cells is accelerating adoption of these techniques.

In this work, we review operando optical characterization tools applied to battery research. A recently developed diagnostic using attenuated total reflection infrared spectroscopy is also presented, including applications in lithium sulfur and lithium ion batteries. Operando measurements of the polysulfide shuttle mechanism in a Li-S battery is presented, including the impact of additives on the shuttle mechanism. Electrolyte decomposition in Li-ion batteries during SEI formation is also reported. Finally, operando measurements of electrolyte chemical stability during battery operation at elevated temperature is presented. An optical thermometry technique is also demonstrated for internal battery temperature measurements.
Pressure Evolution in Constrained Li Metal Pouch Cells
Authors: Raj Abhi , Dickerson Charles C , Niu Chaojiang , Xiao Jie , Steingart Daniel A. , Dufek Eric J. , Liaw Boryann
Published: February 2020

Increased research in lithium metal anodes has been motivated by a rising need for high energy density batteries for transportation and portable electronics applications. While promising a low redox potential and high specific capacity, lithium is hindered by nonuniform deposition on the anode surface, as well as unwanted side reactions with the electrolyte as fresh lithium is exposed during discharge. The majority of research in this area has been done with coin cells [1, 2], which are unsuitable for scaling towards practical applications and mask variations across an electrode as well as gas evolution during cycling.

In this work, we demonstrate the use of a fixed-gap fixture to monitor pressure evolution across a 7-layer Li metal/NMC 622 pouch cell. While initial cycles exhibit a linear and reversible change in pressure as a function of state of charge, the baseline pressure steadily increases at the end of discharge with continued cycling, indicating lost inventory of lithium. Moreover, towards the end of cycling as the cell approaches sudden failure, large increases in baseline pressure are correlated to gas evolution within the cell. These correlations are further supported by electrochemical data, specifically through changes in polarization at the beginning of a charge or discharge step, or through peaks in dQ/dV curves at later stages during charge.

References:

[1] Xu, W. et al., “Lithium metal anodes for rechargeable batteries,” Energy Environ. Sci., 2014, 7, 513-537. DOI: 10.1039/C3EE40795K

[2] Liu, Y. et al., “An Artificial Solid Electrolyte Interphase with High Li-Ion Conductivity, Mechanical Strength, and Flexibility for Stable Lithium Metal Anodes,” Adv. Mater., 2017, 1605531. DOI: 10.1002/adma.201605531
(Invited) Synchrotron X-Ray Spectroscopy and Imaging for Studying Intercalation Battery Chemistries
Authors: Lin Feng
Published: February 2020

The advancement of battery materials has been accelerated by new characterization methods that are capable of probing battery chemistries at various length and time scales. Synchrotron X-ray techniques stand out as one of the most effective methods that allow for nearly nondestructive probing of materials characteristics such as electronic and geometric structures with various depth sensitivities through spectroscopy, scattering, and imaging. In this presentation, we will discuss the state-of-the-art of some X-ray spectroscopic and imaging techniques and their successful applications in gaining fundamental insights into intercalation battery chemistries. We will then provide some examples in lithium ion and sodium ion batteries. Specifically, lithium and sodium layered cathode materials are usually multicomponent transition metal (TM) oxides and each TM plays unique roles in operating the cathode chemistry, e.g., redox activity, structural stabilization, surface passivation. Engineering the three-dimensional (3D) distribution of TM cations in individual primary and secondary particles can take advantage of the depth-dependent charging and passivation mechanisms. This will enable a path towards tuning local TM–O chemical environments and eliminating undesired cathode–electrolyte interfacial reactions that are responsible for capacity fading, voltage decay, and safety hazards. We will then highlight our recent progress in understanding and manipulating the cathode chemistry using the unconventional design principle of 3D heterogeneous chemical distribution and advanced diagnostic tools. The presentation will show that “there is plenty of room at the bottom” by tuning nano/meso scale heterogeneities for stabilizing multicomponent transition metal oxides based cathode chemistry in rechargeable batteries. Finally, we will provide a perspective to elaborate how synchrotron techniques can impact the development of next-generation battery chemistries.
Synthesis and Electrochemical Performance of ZnO Nanorods and its Application in Silver - Zinc Secondary Battery
Authors: Nguyen Van Tu , Bui Cuong Duc , Nguyen Hung Tran , Nguyen Hoa Thi , Khuat Binh Hoang , Mai Phuoc Van , Do Huong Tra , Tran Nu Huong
Published: February 2020

Nano materials with high surface area increase the kinetics and extent of the redox reactions, thus resulting in high power and energy densities. In this study, ZnO nanorods was prepared by hydrothermal method and used as an anode for zinc-silver battery. These nanorods are characterized by XRD, SEM, specific surface area analysis, solubility in alkaline, EDX analysis and galvanostatic charge/discharge studies in zinc-silver batteries. The electrochemical measurements of nano ZnO negative electrode in the zinc-silver secondary battery exhibited a stable cycle performance with a discharge capacity of 500 mAh g−1 after 100 cycles that it was 120 mAh g−1 higher than the capacity of bare ZnO.

Keywords: ZnO. Zinc- silver batteries. Anode. Hydrothermal method.
Four-Electrode Setup for Electrochemical Impedance Spectroscopy Study of Lithium–Sulfur Batteries
Authors: Fang Jie , Ghashghaie Sasan , Shahzad Hafiz Khurram , Chung Chi Yuen
Published: February 2020

The practical lithium-sulfur batteries (LSBs) show less capacity and energy density than the theoretical values (1675 mAh/g and 2570 Wh/kg) [1]. The insulated Li2S (the end-product of discharge) and dissolved polysulfide intermediates lead to a growth of internal resistance, which reduces the output voltage, rate performance, and efficiency of energy storage. Although the internal resistance of LSBs has been investigated by the EIS method for studying fading mechanism, polysulfides reactivity, and diffusivity, it is still a challenge to in situ monitor the impedance of cathode and anode [2,3]. We have compared cells with two and three-electrode setups for EIS measurements and demonstrated the influence of electrochemical asymmetric in three-electrode setup. To overcome the drawback of the three-electrode cell, a novel four-electrode symmetric cell was proposed. The resistance of the anode solid electrolyte interphase (SEI), the interface between the porous current collector and the case of the coin cell, the electrolyte in the separator, porous structure, and the charge transfer process of active materials were evaluated at a different state of dis/charge. The change of polysulfides concentration induced a mountain in the resistance maps of anode SEI and the electrolyte in the separator. The liquid state polysulfides and solid phase Li2S came together to produce two resistance peaks in the map of the porous structure. For charge transfer resistance, there were two local minima which were caused by the reactions of different polysulfide species. Moreover, the passivation of the cathode by Li2S gave a high charge transfer resistance and limited the complete use of active materials. The increase of electrolyte resistance in the separator indicated a continued consumption of electrolyte.

References

[1] B.D. McCloskey, Attainable gravimetric and volumetric energy density of Li–S and Li Ion battery cells with solid separator-protected Li metal anodes, J. Phys. Chem. Lett. 6 (2015) 4581–4588. doi:10.1021/acs.jpclett.5b01814.

[2] Z. Deng, Z. Zhang, Y. Lai, J. Liu, J. Li, Y. Liu, Electrochemical impedance spectroscopy study of a lithium/sulfur battery: Modeling and analysis of capacity fading, J. Electrochem. Soc. 160 (2013) A553–A558. doi:10.1149/2.026304jes.

[3] S. Drvarič Talian, J. Moškon, R. Dominko, M. Gaberšček, Reactivity and Diffusivity of Li Polysulfides: A Fundamental Study Using Impedance Spectroscopy, ACS Appl. Mater. Interfaces. 9 (2017) 29760–29770. doi:10.1021/acsami.7b08317.
(Invited) Unravelling Solvation Phenomena in Glyme-Based Electrolytes for Na-O2 Batteries
Authors: Ortiz Vitoriano Nagore , Sacci Robert L , Bridges Craig A. , Arcelus Oier , Enterria Marina , Carrasco Javier , Veith Gabriel M.
Published: February 2020

Research into new energy storage technologies, for both portable and stationary applications, has become an urgent necessity. Rechargeable metal-air (oxygen) batteries are receiving intense interest as possible alternatives to lithium-ion batteries, because of their potential to provide higher gravimetric energies. While much attention has been focused on aprotic Li-O2 batteries, substantial challenges must be addressed before widespread commercialization is possible. Recently, a metal-air battery in which lithium has been replaced by sodium has received increasing attention.1 Although Na-O2 batteries (NABs) present lower gravimetric energies on a cell basis (1605 or 1108 Wh/kg based on Na2O2 or NaO2 discharge products, respectively)2 than Li-O2 batteries (3505 Wh/kgLi2O2),3 much lower charge overpotentials (~100 mV) than those in typical Li-O2 batteries (~1000 mV) have been reported based on reversible sodium superoxide (NaO2) formation.

At present, Na systems have mostly been designed according to strategies developed for Li-O2 research which, though a useful initial approach, may have led to the use of suboptimal materials due to the current lack of exploration in this area. The vast majority of the work has been devoted to electrode materials, with little or negligible work on electrolytes which – as the component responsible for ion transportation between the electrodes - are key of any optimized NAB system.

Glyme-based solvents have been widely used in NABs but their selection seems arbitrary and most of the studies do not consider the differences these glymes might have. In this work, we demonstrate that the selection of the solvent plays an important role on the cell chemistry and performance. The coordination number of different glymes measured by infrared spectroscopy and coupled with density functional theory revealed different solvation behavior. Moreover, the enthalpy of dissolution measured using isothermal microcalorimetry varies significantly as a function of solvent selection. In addition, the rechargeable nature of Na-O2 batteries is governed by the formation and oxidation of NaO2, making it vital to study the effect of the electrolyte in the presence of NaO2, and also to prevent the formation of irreversible side products.

References

1 I. Landa-Medrano, C. Li, N. Ortiz-Vitoriano, I. Ruiz de Larramendi, J. Carrasco and T. Rojo, J. Phys. Chem. Lett., 2016, 7(7), 1161–1166.

2 P. Hartmann, C. L. Bender, M. Vračar, A. K. Dürr, A. Garsuch, J. Janek and P. Adelhelm, Nat. Mater., 2013, 12, 228–32.

3 D. G. Kwabi, N. Ortiz-Vitoriano, S. A. Freunberger, Y. Chen, N. Imanishi, P. G. Bruce and Y. Shao-Horn, MRS Bull., 2014, 39, 443–452.
Thermal Runaway of Large Format Pouch Lithium Ion Cell with Internal Temperature Detection Using Extended Volume Accelerating Rate Calorimetry
Authors: Xu Chengshan , Feng Xuning , Lu Languang , Ouyang Minggao , Jiang Fachao
Published: February 2020

Extended volume accelerating rate calorimetry(EV-ARC) has been widely used to judge the thermal runaway(TR) behaviors of large format lithium ion cells in adiabatic atmosphere[1].Generally, when temperature reaches the onset temperature(approximately 90℃)，self heating of the cell begins due to the solid electrolyte interface(SEI) decomposition. And other exothermic chemical reactions start when temperature reaches their onset temperature. These reactions will heat the cell and at last lead to thermal runaway of the cell. The onset temperature, triggering temperature and maximum temperature are important factors to judge hazardous during TR.

When testing TR of pouch cells using EV-ARC, the thermal couple is always placed between two side by side cells[2]. However, temperature detected between two cells is not the real temperature inside battery. In this work, the thermal couple is inserted into the cell directly to detect the inside temperature of cell(see Figure1). The capacities of fresh cell and operated cell are almost the same. Then, the EV-ARC tests of both cells are conducted and compared. In the result, the onset temperature of both cells are almost the same. The triggering temperature of cell with thermal couple inside is about twenty degree higher than that detected between two cells. And the maximum temperature of cell with thermal couple inside is also dozens of degree higher than that with traditional test method.

Figure 1
Effect of Mechanical Stress Factors on Large Format Li-Ion Cell Thermal Runaway Characteristics
Authors: Graika Jason , Barrera Thomas P. , Alobaidi Yasir
Published: February 2020

Expansion and contraction of Li-ion cell electrodes during cycling is known to exert mechanical stress and strain within cell components. During cell charge, Li-ion intercalation into the graphite anode structure increases anode swelling and thickness. Upon cell discharge, Li-ions de-intercalate from the carbon anode structure causing cell-level relaxation and a proportional reduction in cell swelling. Li-ion cell swelling has been shown to be a function of cell discharge rate, state-of-charge (SoC), and age. The impact of mechanical stress-strain swelling on Li-ion cells creates high contact pressure between electrode layers, degrades conductive carbon particle contact resistance, and irreversibly deforms the cell case structure. Mechanical stress loading also causes fatigue within internal cell components leading to an increase in cell impedance and capacity loss which may reduce cell cycle life performance.

Li-ion battery (LIB) manufacturers have long recognized that the effects of cell-stack level stress fatigue on battery module architectures must be considered in LIB packaging designs requiring long cycle life performance. In LIB designs utilizing prismatic or elliptical-cylindrical cell geometries, cells are commonly packaged into modules by restraining the module stack by compression loading. In this manner, the adverse effects of cell stack deformation during charge-discharge cycling can be mitigated. In space applications, compression loading of cell modules also enables LIB’s to survive launch vehicle shock and vibration environments at high SoC’s.

More importantly, mechanical abuse of LIB’s can result in an energetic catastrophic failure event. At high SoC’s, the hazards of a LIB safety incident may include venting, smoke, and fire indicative of catastrophic thermal runaway. Recently, the NASA has investigated the severity and consequences of catastrophic thermal runaway of large format Li-ion cell-based LIBs for human space flight applications. Thermal runaway safety testing of certain space-qualified Li-ion cell designs has shown that there is a correlation between applied cell compression forces and thermal runaway severity. This work focuses on the relationship between compression force and SoC on large format Li-ion cells qualified for human space flight applications. Empirical results from simulated internal short circuit trigger testing designed to induce catastrophic thermal runaway will be discussed.

References:

Bang, H.J., Thillaiyan, R., and Quee, E., 2013 NASA Aerospace Battery Workshop, Huntsville, AL, November 5-7, 2013.

Cannarella, J. and Arnold, C.B., J. Power Sources 269 (2014) 7-14.

Oh, K.Y., Epureanu, B.I., Siegel, J.B., and Stefanopoulou, A.G., J. Power Sources 310 (2016) 118-129.

Graika, J., Barrera, T., and Alobaidi, Y., 2018 NASA Aerospace Battery Workshop, Huntsville, AL, November 27-29, 2018.

Figure 1
Overcharging Li(Ni0.5Mn0.3Co0.2)O2//Graphite Cells: A Systematic Study
Authors: Bloom Ira , Dietz Rago Nancy L. , Graczyk Donald G , Tsai Yifen , Naik Seema , Lee Eungie , Du Zhijia , Sheng Yangping , Li Jianlin , Wood David L. , Steele Leigh Anna M , Lamb Joshua , Spangler Scott , Grosso Christopher , Fenton Kyle R
Published: February 2020

Lithium-ion batteries have become the leading energy storage technology for automotive applications. During operation, a passivating or solid electrolyte interphase (SEI) layer forms on both electrodes. The structure and composition of the SEI layers at the electrode surfaces are complex under normal operating conditions [1-4]. However, there are very few reports in the literature that describe how the SEI changes under abusive conditions, such as overcharge. Understanding these changes is potentially very useful from a safety viewpoint since it might help us create robust cells that are tolerant of overcharge.

Argonne, Oak Ridge and Sandia National Laboratories collaborated to understand the physical and chemical changes that occur in small pouch cells that were charged to 100, 120, 140, 160, 180 and ~250% SOC. The SEI layer on the graphite anode surface was characterized using scanning-electron microscopy, X-ray photoelectron spectroscopy, chemical analysis and high-performance liquid chromatography. We found that the structure and chemistry of the SEI layer was sensitive to the extent of overcharge, the binder in the cathode, and the nature of the cathode. These and other findings will be discussed.

References

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We gratefully acknowledge support from the U. S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office. Argonne National Laboratory is operated for DOE Office of Science by UChicago Argonne, LLC, under contract number DE-AC02-06CH11357.

The work at Oak Ridge National Laboratory was sponsored by U. S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office, Applied Battery Research. Oak Ridge National Laboratory is managed by UT Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.

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 (NNSA) under contract DE-NA0003525.

The U.S. government retains for itself, and others acting on its behalf, a paid-up nonexclusive, irrevocable worldwide license in said article to reproduce, prepare derivative works, distribute copies to the public, and perform publicly and display publicly, by or on behalf of the government.
Phase-Field Modeling of Solid Electrolyte Interphase (SEI) Evolution: Considering Cracking and Dissolution during Battery Cycling
Authors: Liu Lin , Guan Pengjian
Published: February 2020

Lithium-ion battery (LIB) degrade over time, which compromise its electrochemical performance and mechanical integrity, eventually battery safety. The evolution of solid electrolyte interphase (SEI) layer, which is a passivation layer forming and growing between electrode and electrolyte, is one of the main reasons for the above degradation of LIB. The performance and longevity of LIB highly depend on the stability of the SEI. Unfortunately, it is believed that the SEI layer is not electrochemically and mechanically stable due to the dissolution and cracking of the SEI during the de/lithiation process. Up to date, very few studies have investigated the dissolution and cracking of the SEI layer during the lithium-ion diffusion. In this work, a phase field model is developed to provide insight on the interaction effect of cracking and dissolution of the SEI layer on LIBs performance. We assume that the SEI layer is formed by different solid species precipitated from the electrolyte, which are not stable during the de/lithiation cycling. SEI layer experiences stress concentration and volume change, which lead to the cracking of layer. In the meanwhile, the SEI species may have further reactions with the electrolyte which may lead to the dissolution. The cracking of the SEI layer results in more surfaces to react with electrolyte, and further dissolution, as shown in Figure 1. Moreover, we carry out experiments to focus on imaging the SEI as well as battery performance degradation during SEI formation and evolution.

Figure 1
Electrochemical Exfoliation of Graphite in the Presence of Metal Complexes
Authors: El Khakani Soumia , Bélanger Daniel
Published: February 2020

Among 2D materials, graphene is by far the most attractive one due to its distinguished electronic, chemical and mechanical properties. It has been used in a large number of applications covering electrical devices, reinforced composite materials and energy storage to only cite a few. Besides its intrinsic properties, the applications of graphene can be extended to other fields by functionalizing it using different molecules and/or particles. It is even more interesting when the production and functionalization of graphene can be achieved in a single-step process. In this work, we report on a single-step synthesis of functionalized graphene using electrochemical exfoliation of graphite sheets in an acidic medium containing metallic complexes. The resulting materials were characterized using transmission electron microscopy, X-ray photoelectron spectroscopy, electrochemical techniques, Raman spectroscopy and inductively coupled plasma atomic emission spectroscopy.
Insight into the Effect of Cationsin Ionic Liquidelectrolytes on Charge Storage Capacity of High-Performance Supercapacitors of N-Doped Graphene Aerogels
Authors: Wuamprakhon Phatsawit , Krittayavathananon Atiweena , Sawangphruk Montree
Published: February 2020

Even though room temperature ionic liquids (RTILs) have been widely used as electrolytes in electrochemical applications including supercapacitors and batteries, the behavior of RTILs at charged interfaces is still not well understood. The cations are expected to have a significant effect on physical properties (i.e., electrolyte viscosity and conductivity) as well as the electrochemical performance.1, 2 For a fully understanding of the cation-effect, herein, we provide a systematic study of the influence of the physical properties of RTIL electrolytes with different structures of cations on the electrochemical performance of carbon-based supercapacitors along with a molecular dynamics (MD) simulation. N-doped reduced graphene oxide aerogel (N-rGO) supercapacitors are incorporated with RTIL electrolytes consisting of cyclic nitrogen-based cations i.e., imidazolium, which are connected with a variable length of alkyl chains (i.e., ethyl, butyl and hexyl). Changing these cations do not widen the potential window of the ionic liquid; however, they do affect the electrochemical performance in term of specific capacitances and specific energies of the supercapacitor. We found that the heterocycles of RTILs affect ionic conductivity while the alkyl chain plays a role in ion diffusion. In this perspective, we hope that this fundamental study may pave the way to design the structure of RTIL electrolyte for high energy storage performance.
Optical Properties Alteration and Photo-Voltaic Applications of Nitrogen-Doped Graphene Quantum Dots
Authors: Hasan Md Tanvir , Gonzalez-Rodriguez Roberto , Naumov Anton V
Published: February 2020

In this work, a simple/scalable microwave-facilitated hydrothermal route is used to produce nitrogen self-doped graphene quantum dots (NGQDs) from a sole glucosamine precursor. These NGQDs with average sizes of ~6nm show bright/stable fluorescence both in the visible and near-IR. The structural and optical properties of as-prepared NGQDs are further altered to provide control for optoelectronic applications by using ozone, thermal and laser treatment. Both laser and thermal processing serve as controllable avenues to decrease GQD emission via anticipated reduction processes. Oxidative ozone treatment results in the decrease of GQD average size down to 5.23 nm and a more disordered structure due to the introduction of the new functional groups. Structural and optical characterization was performed utilizing TEM, AFM, SEM, FTIR, EDX, Raman, fluorescence and absorbance. FTIR, EDX and Raman data suggest that this processing introduces oxygen-containing functional groups, enhancing the atomic percentage of oxygen and increasing ID/IG ratio. Ozone treatment shows enhancement of visible emission is observed from 0 to 16 min ozone processing with following over oxidation-induced defect-related quenching. On the other hand, progressive increase in defect-related NIR emission is observed up to 45 min. Such alteration of optoelectronic properties of GQDs is used to enhance their performance in photovoltaic devices.

Untreated NGQDs (Un-NGQDs) and ozone-treated NGQDs (Oz-NGQDs) are utilized as a photoactive layer to fabricate a variety of solar cells. Although devices with untreated NGQDs show performances similar to existing reports, Oz-NGQDs exhibit significant improvement with maximum PCE of 2.64% and a short circuit current density of 4.8 mA/cm2 and an open circuit voltage of ~0.65V with a fill factor of ~83.4%. This enhancement can be potentially attributed to the increased/broadened visible absorption feature in device state due to the efficient charge transfer between the hole-blocking layer of TiO2 and Oz-NGQD having enhanced concentration of functional groups. This work suggests ozone treatment as an easy and powerful technique to alter the optoelectronic properties of versatile and scalably produced NGQDs which can be successfully utilized as an eco-friendly photoactive layer to boost the photovoltaic performance of solar cells.
(Invited) Robust Two- and Three-Dimensional Conjugated Organic Structures for Electrochemical Applications
Authors: Baek Jong-Beom
Published: February 2020

Robust conjugated two- (2D) and three-dimensional (3D) non-metallic conductive structures have attracted immense interest due to their unusual electronic, optoelectronic, magnetic and electrocatalytic properties. Their tunable structures and properties promise to offer many opportunities in various applications. Nevertheless, methods developed for the synthesis of non-metallic conductive materials, which are capable of producing fused-aromatic based stable frameworks with uniformly decorated heteroatoms with/without holes, remain limited, even after decades of intensive exploration in science and technology. To overcome these issues, stable organic materials have been designed and synthesized. They have uniformly distributed heteroatoms,1 holes with heteroatoms2 and transition metal nanoparticles in the holes.3 The structures were confirmed using various characterization techniques, including scanning tunneling microscopy (STM). Based on the stoichiometry of 2D layered structures, they were, respectively, designated C2N, C3N, C4N, and M@C2N (M = Co, Ni, Pd, Pt, Ru). Their electronic and electrical properties were evaluated by electrooptical and electrochemical measurements along with density-functional theory (DFT) calculations. Furthermore, robust three-dimensional (3D) cage-like organic materials have also been constructed and they show high sorption properties.4,5 The results suggest that these newly-developed 2D and 3D non-metallic conductive materials offer greater opportunities, from wet-chemistry to device applications.

References:

[1] Mahmood, et al. Two-dimensional polyaniline (C3N) from carbonized organic single crystals. Proceedings of National Academy of Sciences, USA 2016, 113, 7414.

[2] Mahmood, et al. Nitrogenated holey two-dimensional structure. Nature Communications 2015, 6, 6486.

[3] Mahmood, et al. An efficient and pH-universal ruthenium-based catalyst for the hydrogen evolution reaction. Nature Nanotechnology 2017, 12, 441.

[4] Bae, et al. Forming a three dimensional porous organic network via explosion of organic single crystals in solid-state. Nature Communications 2017, 8, 159-Highlighted in Nature Nanotechnology 2018, 13, 4.

[5] Mahmood, et al. A robust 3D cage-like ultramicroporous network structure with high gas uptake capacities. Angewandte Chemie International Edition 2018, DOI: 10.1002/ange.201800218.