bluuebunny/crossref_metadata_2025 huggingface dataset:
Functionality Impacts on Reaction Rates for Single Compounds and Simple Mixtures of Aldehydes and Ketones
Authors: Holladay Jamelyn , Lilga Michael , Padmaperuma Asanga
Published: February 2020

In recent years there has been growing interest in using electrochemical methods for hydrogenation of organic materials. Conventional hydrogenation technologies require elevated temperatures and externally supplied high pressure (2000psi) hydrogen. The same reactions can be performed using an electrochemical reactor at close to room temperature and with no externally supplied hydrogen. For this paper, we will present our research examining a series of aldehydes and ketones, specifically: benzaldehyde, acetophenone, 2-hexanone, pentanal, fructose and glucose. These materials allow us to examine the impacts of different functionalities on reaction kinetics. In addition to examining single compounds, simple mixtures will be examined to better understand the kinetic impacts. These tests are being done in conventional H-Cells with a Nafion separator, as well as in a flow cell with an integrated reference electrode. A series of platinum and copper based catalysts were used in the tests. We have studied novel cell structures and electrode materials to improve the current efficiency for electrochemical reduction of organic species. Promising results have been observed where significant hydrogenation has been found. A description of work conducted and discussion of results will be presented.
Role of the Unsaturated Groups in the Covalent Modification By the Carboxylate Oxidation: Mechanistic Aspects
Authors: Morales-Martínez Daniel , González Felipe J
Published: February 2020

The oxidation mechanism of tetrabutylammonium carboxylates RCOO- involves the formation of radicals R• and carbocations R+, whose reactivity towards carbon surfaces allow the covalent grafting of the surface [1]. Experimental results have shown that the presence of the unsaturated terminal groups in the carboxylate structure are a determining factor for the covalent modification [2]. However, the role of these unsaturated groups in the mechanism is unknown. Therefore, in this work the study the oxidation of some carboxylates in presence of molecules with unsaturated groups (naphthalene and hexyne) was done. The results showed the intervention of a redox reaction between the carbocations R+ got from the carboxylate oxidation and the unsaturated molecule. This reaction regenerates the radical R• and allows the covalent modification. When naphthalene was used as additive, this molecule was also attached to the carbon surface. This observation arises from the fact that the oxidation response for the naphthalene groups attached to the surface was observed, confirming the electron transfer between the unsaturated group and the carbocatión R+. On the other hand, in the case of the hexyne, the solvent effect in the mechanism was studied, showing an association product between acetonitrile and hexyne. This fact helps to understand the specie that interacts with the carbocation in the redox reaction. These results give new insights about the covalent modification by carboxylate oxidation.

[1] C.P. Andrieux, F. Gonzalez, J.M. Savéant., J. Am. Chem. Soc., 119, 1997, 4292.

[2] D. M. Hernández-Morales, F. J. González., Electrochem.
Comm., 46, 2014, 48.

Figure 1
Electrochemical Characterization of Fischer Biscarbene Complexes of Chromium
Authors: Hoskovcová Irena , Metelková Radka , Váňová Hana , Tobrman Tomáš , Dvořák Dalimil , Ludvík Jiří
Published: February 2020

Carbene complexes are characterized by presence of a formally double bond M=CR2. In electrophilic carbenes of Fischer type, the Mδ– = Cδ+ polarity of this bond is typical. An extended study of mononuclear complexes (CO)nM = C(NR’)R showed that there are two rather independent redox active centers present: oxidation is aimed on the metal atom, reduction on the carbene moiety.[1] This picture is in agreement with their HOMO and LUMO composition. [2]

Studied biscarbenes: (CO)5 Cr = C(X) - bridge - C(X) = Cr (CO)5 ; bridges: 1,3- or 1,4-phenylene, bis-, tris-, tetrakis-2,5-thienylene and their combinations; X: dialkylamino- or alkoxy-

Biscarbenes belong to molecules with multiple redox centres as they comprise two oxidizable metal atoms together with two reducible carbene moieties connected by a bridge. Electronic communication manifests itself in the course of redox process depending on the electronic properties of the bridge. It is evaluable by analysis of electrochemical behavior of the compounds in the frame of homologous series and with respect to their mononuclear analogs.

For oxidation, the extent of this communication can be identified by occurrence of two subsequent oxidation signals whereas in absence of the electronic communication both the metals are oxidized at the same potential. Potential of the first oxidation step of biscarbenes does not differ from that of monocarbenes indicating lack of the communication.

The reduction process of biscarbenes is influenced by the reducibility of the bridge itself, and by its participation in the LUMO. Since the reduction of biscarbenes is substantially easier than that of monocarbenes, the bridge is involved in the delocalization system and the amino or alkoxy substituent X plays important role in tuning of the reduction potential.

Recently, a new modular synthesis of biscarbenes [3] has open a way to molecules with longer bridging groups with various intramolecular conductivity.

Acknowledgement: Financial support from GACR 17-21770S and from specific university research (MSMT No 20/2017) is gratefully acknowledged.

References:

[1] Ludvík, J.; Hoskovcová, I.; in Advances in Organometallic Chemistry and Catalysis: The Silver/Gold Jubilee Int. Conf. on Organomet. Chem. Celebration Book; Pombeiro, A. J. L., Ed., Wiley 2014, pp. 653

[2] Kvapilová, H.; Hoskovcová, I.; Ludvík, J. ; Záliš, S. Organometallics
2014,
33, 4964,

[3] Váňová, H.; Tobrman, T.; Hoskovcová I.; Dvořák D. Organometallics
2016, 35, 2999
Invited: Approaching Hydrogenase-like Performance with Molecular Electrocatalysts for H2 Production
Authors: Wiedner Eric S. , Klug Christina M. , Cardenas Allan J. , O'Hagan Molly , Appel Aaron M. , Bullock Morris
Published: February 2020

Hydrogenase enzymes mediate the electrochemical production of H2 at fast rates (>9,000 s–1) and low overpotentials (<100 mV). Synthetic nickel(II) complexes containing diphosphine ligands with pendant amines can catalyze the production of H2 at rates that exceed the hydrogenase enzyme, but typically exhibit much larger overpotentials. Recent efforts from our group have focused on designing new nickel catalysts that produce H2 with rates and overpotentials that are comparable to hydrogenase enzymes, which requires controlling multiple aspects of the catalyst structure and function. This talk will describe the individual and combined effects of (1) incorporating electron withdrawing groups at phosphorus, (2) preventing formation of inactive exo-pinched isomers through control of ligand structural dynamics, and (3) matching the solution pH to the basicity of the pendant amines in the catalyst.
A Novel Graphene Modified Electrochemical Sensor for Ultrasensitive Detection of T1D Serum Autoantibody
Authors: Premaratne Gayan , Patel Manoj Kumar , Krishnan Sadagopan
Published: February 2020

Recently, autoantibody biomarkers have been reported for early diagnosis of type 1 diabetes (T1D) also known as insulin-dependent diabetes mellitus or juvenile diabetes. Our objective is to design an electrochemical immunosensor to detect glutamic acid decarboxylase antibodies (GADA) from serum as a diagnostic measure for T1D. The sensor is designed on a screen printed eight electrode array (AuSPE) made of gold working electrodes, gold counter electrode, and a silver pseudo reference electrode. Protein A/G coated magnetic beads were used to capture the GADA spiked in 5% human serum samples. The antibody-captured by the magnetic beads were allowed to bind with the surface antigen (GAD-65) immobilized onto the carboxylated graphene oxide modified working electrode surface by carbodiimide chemistry. Both differential pulse voltammetry and Faradaic electrochemical impedance techniques were able to detect ultra-low levels of GADA.

Acknowledgements: We are grateful for the financial support by the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health under Award Number R15DK103386.
A Self-Sustained Photoelectrochemical System with Anodic Rgo/ZnIn2S4/g-C3N4 p-n-Hetero-Junction Catalyst for Antibiotic Wastewater Degradation
Authors: Yu Tingting
Published: February 2020

The use of natural sunlight or indoor light for heterogeneous semiconductor photocatalysis is a promising alternative technology that could help address increasing environmental threats including water pollution and the energy crisis. A novel ternary hetero-junction of rGO/ZnIn2S4/g-C3N4 photo-electro-catalyst was prepared by a simple hydrothermal method.

By SEM or XRD, the morphology and the composition of the rGO/ZnIn2S4/g-C3N4, ZnIn2S4/g-C3N4, ZnIn2S4 and g-C3N4 were studied. Anode coated with rGO/ZnIn2S4/g-C3N4 has more smaller nanoparticles than others. This means that the positive effect of the layered GO and g-C3N4 increased the surface areas and made the catalyst more uniformly. XRD of the rGO/ZnIn2S4/g-C3N4 showed the typically peaks of ZnIn2S4. GO and g-C3N4 induce the formation and growth of ZnIn2S4 on the surface. The UV-vis diffuse reflection spectrums are compared in Fig. 2. Both the pure g-C3N4 and ZnIn2S4 have an absorption in the visible light region. After the combination of GO, ZnIn2S4 and g-C3N4, the enhanced absorption in the visible region is clearly observed compared to pure ZnIn2S4 or g-C3N4.

The anode was the rGO/ZnIn2S4/g-C3N4 catalyst coated on carbon fiber and carbon fiber with Pt nanoparticles was used as the cathode in a self-sustained catalytic fuel cell for triclosan degradation. Electron transferred spontaneously without additional applied voltage and this save the energy consumption. Triclosan (98.8%) was degraded after 30 minutes in the self-biased system (1000 Ω). Potential degradation mechanisms for pollutants were proposed. ZnIn2S4 was the P-type semiconductor and g-C3N4 was a N-type semiconductor. The conduction band of g-C3N4 is more negative than ZnIn2S4 and ZnIn2S4 is more negative than rGO. An interior bias can be produced to transfer the localized e- of g-C3N4 to ZnIn2S4 and and combination with the h+ of ZnIn2S4. Aeration and activation of molecular oxygen by the e- of ZnIn2S4 in the fuel cell, lead to the formation of reactive oxidizing species. The holes of g-C3N4 oxidized H2O and generated •OH for triclosan removed.

This photoelectrochemical system was conducive to the separation of photo-generated e-/hole pairs and e- transfer to the cathode irrespective of light. Compare to the traditional method, it can remove pollutants without light irradiation or any externally applied voltage. This new catalytic pollution control route can lower the energy consumption and may degrade many kinds of pollutants.

Figure captions:Mechanism of the self-biased photoelectrochemical system.

Figure 1
Square Wave Bipolar Electrochemistry for the Detection of Proteins
Authors: Shannon Curtis , Yu Songyan
Published: February 2020

Rapid and specific quantitation of proteins is desirable for assays used at the point-of-care, as well as in clinical and research laboratories. The advantages of such devices include short turnaround times for acquiring critical data, low cost, and improved patient compliance with diagnosis and therapeutic regimens. Electrochemical detection is currently employed in a wide range of biosensors because of its inherent signal stability, high sensitivity, and ease of calibration. Our laboratories have developed the electrochemical proximity assay (ECPA) for protein detection, a sensitive and selective assay based on the electrochemical detection of surface-confined affinity complexes. ECPA demonstrates extremely high sensitivity (e.g., 10 fM for insulin).

Bipolar electrodes (BPEs) have been used for decades in industrial applications ranging from organic electrosynthesis to catalysis. Recently, sensor platforms have been reported in which electrochemiluminescence (ECL) is used to readout the state of a bipolar sensor operating under steady state conditions. In these measurements ECL intensity is directly proportional to the analyte concentration. In contrast to these conventional amperometric sensors, the ECPA signal is based on a surface limited reaction, and therefore does not lend itself to such a straightforward readout strategy. In this paper, we describe the development of an ECPA based on a bipolar platform in which a square wave voltage program is employed both to interrogate and reset the redox state of the surface confined affinity complex. Signal averaging over multiple cycles allows us to detect proteins at low concentration levels.
CO Adsorption on Different Oxide-Supported Catalysts Studied By a Combination of in Situ X-Ray Absorption Spectroscopy (XAS) and Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS)
Authors: Roth Christina , Lentz Claudia , Melke Julia , Reinholz Uwe , Buzanich Ana Guilherme , Riesemeier Heinrich , Narayan Manoj Krishna Kayarkatte , Derr Igor , van der Bosch Nils
Published: February 2020

Polymer electrolyte membrane fuel cells are promising systems in a future sustainable energy scenario. In the so-called power-to-gas strategy, the supply of hydrogen produced by intermittently available wind and solar energy will be converted into electricity on demand using a combination of water electrolysis and fuel cells. However, in order to make this dream a viable reality, material costs need to be dramatically reduced and material stability significantly enhanced.

State-of-the-art catalysts for fuel cell applications are Pt nanoparticles supported on various carbon substrates, predominantly carbon black, but also carbon nanotubes or graphene. However, in the harsh conditions at the fuel cell cathode, carbon is not stable and catalyst degradation due to carbon support corrosion becomes a key issue. One concept towards enhanced durability is to replace carbon by more stable support materials, such as electron-conducting (doped) oxides. Substituting carbon by e.g. tin oxide can alter the catalytic activity significantly, as in contrast to carbon supports the oxide phase may take part in the electrocatalytic reaction (so-called metal-support interaction).

We use CO as a probe molecule to study the interaction between Pt nanoparticles and the support, as the CO-Pt adsorption is affected by the support underneath the Pt nanoparticles. A novel in-situ cell was developed to allow for a combination of X-ray absorption spectroscopy (XAS) and diffuse infrared Fourier transform reflectance spectroscopy (DRIFTS) at the same time and with high quality [1, 2]. We thus benefit from the DRIFTS being able to distinguish between different CO binding sites (atop, bridge, analyzed also by DFT calculations [3]) and XAS being able to probe adsorption and nanoparticle structure. Differences in gas phase IR spectra during static and continuous CO adsorption on platinum nanoparticles reveal information on the influence of the support as well as on the binding sites. In this study, XAS and DRIFTS were recorded simultaneously for Pt/C, Pt/SnO2, Pt/ATO and Pt/ITO and analyzed with respect to kind of surface adsorbates, binding sites, coverage as well as nanoparticle structure.

[1] A. Drochner, M. Fehlings, K. Krauss, H. Vogel, Chem. Eng. Technol. 23 (2000) 319-322.

[2] C. Brieger, J. Melke, N. van der Bosch, A. Schökel, M. Krishna, I. Derr, M. Labza, C. Roth, J. Catal. 339 (2016) 57-67.

[3] C. Lentz, S. P. Jand, J. Melke, C. Roth, P. Kaghazchi, J. Molecular Catal. A: Chemical (2016), article in press.
(Physical and Analytical Electrochemistry Division David S. Grahame Award Address) Nanoscale Templates and Scaffolds for Electrochemical Device Applications
Authors: Birss Viola
Published: February 2020

This talk will review some of our recent fuel cell-related research efforts, which have had a primary focus on increasing the lifetime and performance of both anode and cathode catalyst layers. In our recent work on PEM fuel cells, a new class of ordered, mesoporous carbon materials (both powders and free-standing scaffolds), with nano-engineered pore diameters and lengths, have been developed as support materials to better distribute and stabilize catalytic nanoparticles that are attached to their surface. These carbons have also been surface modified with a range of functional groups, showing that this can significantly alter their wettability, enhance their resistance to corrosion, better anchor catalytic nanoparticles, and are also beneficial in redox flow battery electrochemistry. These reproducibly ordered carbon scaffolds are also proving to be ideal for the investigation of the interactions of Nafion with Pt/carbon in relation to performance, especially as a function of carbon pore diameter, depth and surface hydrophilicity.

In parallel research related to catalyst supports, we have constructed ordered metal oxide nanotubular arrays, then converting them to conducting oxy-nitride forms, primarily to replace carbon. These metal oxy-nitrides undergo interesting redox transitions that will be shown to correlate with the activity of these materials (after deposition of Pt nanoparticles) towards the oxygen reduction reaction. Ordered surface arrays of Zr oxide nanotubes are also very promising for use in novel, nano-structured, high temperature solid oxide fuel cells.
Palladium Electrocatalysts Synthesis: Probing Reducing Agent Effect By XRD, XPS and ORR
Authors: Napporn Teko W. , Holade Yaovi , Canaff Christine , Poulin Suzie , Servat Karine , Arrii-Clasens Sandrine , Kokoh Kouakou Boniface
Published: February 2020

Palladium (Pd) affinity with hydrogen and the subsequent effect on its physical structure is well known in literature. However, the majority of chemical methods for synthesizing Pd-based nanomaterials use sodium borohydride (NaBH4) as reducing agent, which releases hydrogen in aqueous solution. Pd can readily absorb this hydrogen in its lattice and forms PdHx hydrides. Alternatively, organic compounds such as ascorbic acid (AA) can be also used for reducing Pd ions in Pd nanoparticles. Pd nanomaterials are used for various reactions as those in fuel cells. In electrocatalysis where the electrode structure plays a key role, the subsequent impact on the catalytic properties should be carefully examined.. In the present work, reducing agent effect on Pd nanomaterials and their long-term chemical stability (during 2 years) were scrutinized by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). The impact of the hydrogen insertion (into Pd crystalline network) on the electrocatalytic properties of the synthesized Pd nanomaterials is investigated through oxidation of carbon monoxide and oxygen reduction reaction (ORR). It was observed that the surface state of the nanomaterials (Figures 1a-b) prepared by using sodium borohydride as reducing agent (Pd/C-NaBH4) is radically different from those obtained from L-ascorbic acid (Pd/C-AA) (Figure 1c). ORR starts with enhanced kinetics (E > 1 V vs. RHE) in a 4-electron process, producing p(H2O2) < 0.5% associated with excellent durability over 5000 cycles (Figures 1d-e). Both catalysts outperform all reported data for Pd electrocatalysts in alkaline medium. Finally, this work combined ex/in situ XPS and XRD analyses together with ORR as catalytic model towards a clear development in our understanding of Pd affinity with hydrogen and its electrocatalysis.

Figure 1. (a,b) HRTEM micrographs of the as-prepared nanomaterials of Pd/C-NaBH4 and Pd/C-AA and their corresponding high-resolution Pd 3d XPS spectra. (d) The normalized electrochemical surface area (ECSA) behaviour before and after 5000 cycles of accelerated potential cycling test (APCT: 0.6-1 V vs. RHE at 100 mV s−1 in O2-saturated 0.1 M KOH). Note that ECSA was evaluated at 50 mV s−1 and 5 mV s−1 scan rates and had the same trend. (e) ORR polarization curves recorded in a O2-saturated 0.1 M KOH solution at the ring (top) and disc (bottom) for 5 mV s−1 scan rate before (initial) and after APCT (5000 cycles) at RRDE speed of 1600 rpm.

Acknowledgments

The authors gratefully acknowledge financial support from the French National Research Agency ANR-ChemBio-Energy

References

1. Holade Y., et al., ChemElectroChem. 2, 592−599 (2015)

2. Holade Y., et al., RSC Advances 6, 12627−12637 (2016)

Figure 1
Electrochemical Oxidation of Niobium and Tantalum Carbides in Aqueous Solutions
Authors: Walczyk Dustin J. , Mason Daniel , McRae Naquan , Taylor Gregory , Norris Zach , Linderman Kyle , Hettinger Jeffrey , Yu Lei
Published: February 2020

Transition metal carbides have unique properties such as high hardness, high melting point, high thermal conductivity, and high chemical stability. Transition metal carbides have extensive applications in many areas. For example, the refractory and hard ceramic material Niobium carbides (NbC and Nb2C) can be used in tool bits for cutting tools and materials for wearing resistance. It has been reported that early transition metal carbides resembled the valance electron structures and the catalytic properties metals such as Pt and Pd. The metal carbides or the carbide-derived carbon CDC obtained from these metal carbide precursors can be used as supports to reduce the overall loading of the precious metals. Due to its chemical stability and poor sintering ability, research about chemical properties of carbides is restricted in limited areas. Metal carbides can be oxidized at higher temperature with different oxidants such as chlorine or oxygen. At a temperature of 350 oC or higher, metal carbides can react with chlorine gas to be volatile metal chlorides. At room temperature, metal carbides are very stable in many strong acid solutions. However, when electrical potential is applied, metal carbides can be oxidized and metal oxides can be produced and dissolved in solutions. In this report, we investigate the electrochemical properties of a series of metal carbides, NbC, Nb2C, TaC, Ta2C, VC, and V2C in aqueous solutions with the presents of HCl and HF. Cyclic voltammetry and elemental analysis demonstrated that all of these metal carbides can be oxidized electrochemically at a “mild” electrode potential and produce soluble metal ions in the solutions. The CDC on the surface of the electrode after oxidation is porous and either sp3 or sp2 hybridized.
STM Imagings of Smooth Pt Monolayer Allotropes on Au(111) and Their Electrocatalytic Activities Toward Hydrogen
Authors: Liao Weicheng
Published: February 2020

In situ scanning tunneling microscopy (STM) is used to explore the spatial structures of a ordered platinum adlayer deposited on an Au(111) electrode under potential control in double layer region in 0.1 M sulfuric acid. The Pt deposit is prepared by chemical reduction of PtCl6
2- complexes by carbon monoxide (CO) molecules, which generates a one-atom-thick Pt deposit capped by a CO adlayer which impeded the further deposition. The superstructure of the CO on Pt film is (√7×√7)R19.1° in CO free electrolyte, the same as observed on a Pt(111) electrode, suggesting that Pt adatoms are arranged spatially similar to the Pt(111), not Au(111), plane. The CO adlayer is stripped off completely by pulsing the potential to 0.96 V (vs. hydrogen reversible electrode) within 3 s in H2-satruated 0.1 M H2SO4, resulting in a Pt adlayer still organized in a hexagonal lattice with an atomic distance of 0.287 nm which is 3.7% smaller than Au(111)’s and 3.2% larger than Pt(111)’s. The mismatch in lattice dimension between the Pt adlayer and Au(111) substrate yields intricate commensurate structures, exhibiting a corrugated surface morphology, as observed with the reconstructed Pt(111). This phase, dubbed the R phase, is stable only if the potential is more negative than 0.8 V; otherwise, it is converted into a Moiré pattern (M phase). This M phase appears elastic as the interatomic spacing decreases from 0.281 to 0.277 nm from 0 to 0.3 V, and stays at 0.277 nm till 0.95 V, where oxidation and restructuring occur. These R and M phases allotropes show different electrocatalytic activities toward hydrogen evolution and oxidation reactions (HER and HOR), indicating that the atomic structure of the Pt deposit is important in determining its electrochemical properties.

Figure 1
Adsorption of Benzyl Viologen Dichloride and Its Displacement By 3-Mercapto-1-Propanesulfonate during Copper Electrodeposition
Authors: Lu Jing , Barkey Dale P
Published: February 2020

Typical copper electroplating baths used for super-conformal electrodeposition of copper interconnects in submicron-scale vias or trenches on semi-conductor devices contain additives for control of current distribution. The additives operate through absorption and desorption at the metal-electrolyte interface where they regulate the copper deposition rate. In this paper, adsorption of the leveler benzyl viologen dichloride (BV) and its displacement by the accelerant 3-mercapto-1-propanesulfonate(MPS) in an acid-sulfate copper plating bath were studied by means of chronoamperometry. The measured copper deposition rate was taken to be the sum of current densities for surfaces fully covered by either BV or MPS weighted by the fractional surface coverage of each component. At constant potential, current-time curves were recorded during stepwise addition of additives. Figure 1 shows results for addition of BV to a solution that contained no MPS. These measurements provide an isotherm for BV adsorption. Similar measurements were made for stepwise addition of MPS to solutions containing a given concentration of BV to determine the fractional displacement of BV as a function of MPS concentration.

Results showed that BV adsorption and its replacement by MPS are both potential and temperature dependent. Both processes fit the Langmuir model well at low BV or MPS concentrations. The dependence of the Langmuir constant on temperature and potential were also measured. The temperature dependence of the constant indicates that adsorption is a spontaneous exothermic process and its displacement by MPS is a spontaneous endothermic process.

Figure 1
Lithium Metal Deposition during Low Temperature Charge-Discharge Cycles in Lithium Ion Batteries Observed By in Situ 7li NMR
Authors: Arai Juichi , Nakahigashi Rie
Published: February 2020

Lithium metal deposition is induced by a low temperature charging and causes failure in lithium ion batteries (LIBs). Lithium metal deposition during low temperature charge-discharge cycles in LIBs was investigated by in situ
7Li solid state nuclear magnetic resonance (NMR) spectroscopy. Cells composed of LiCoO2 (LCO) and graphite (MAG) were cycled with a continue current (CC) and pulse current (PC) mode at low temperatures (-5, 0 and 5 ℃) to examine kinetics of Li metal deposition. The growth rate, activation energy driven from Arrhenius low for Li metal deposition are evaluated by collecting cell capacities and NMR peak intensities at selected sampling points (e.g., Fig.1 for 0 ℃). The Li metal deposition started after one cycle and reaches the maximum value which is half of the Li amount contained in LCO after 10-20 cycles with CC mode operation at -5 ℃. While, no Li metal depositions were detected at all in the samples operated with PC modes (e.g., 1/2 duty 1 sec width pulse) even after 360000 cycle at -5 ℃. A good correlation between growth rate (n) of deposited Li metal and capacity fading rate (k) in CC mode operation.

Figure 1. Stacked in situ
7Li NMR spectra measured after 1, 10 and 20 cycle charge-discharge at 0 ℃ (experiments were done with two samples for each measurement).
(Invited) Safety of Aged Lithium-Ion Cells
Authors: Jeevarajan Judith A. , Mukherjee Partha P. , Juarez Robles Daniel
Published: February 2020

Lithium-ion batteries have been introduced into large stationary energy storage systems. In recent years, used automotive batteries are being repurposed for use in stationary energy storage systems. It is of significant importance to understand the hazards associated with used cells and batteries and also determine the changes that occur to the cell components such as cathode, anode, separator and electrolyte. Under this study, cells were cycled to various levels of capacity loss and subjected to safety tests such as external short and overcharge. The cell cycling protocol included cycling the cells to the full end of charge and end of discharge voltages as well as reduced end of charge and end of discharge voltages. Cells were removed at 10%, 15% and 20% capacity loss and subjected to external short and overcharge tests. Cells were also cycled under hybrid electric vehicle usage profiles and at different temperatures to characterize the changes.
Lithium Ion Capacitor Safety Testing
Authors: Bolufawi Omonayo , Shellikeri Annadanesh , Zheng Jim P.
Published: February 2020

Lithium – Ion Capacitor (LIC) is a recent innovation in the area of electrochemical energy storage that hybridized lithium ion battery anode material and electric double layer capacitor cathode material as its electrode. The high-power density offered by LIC has made it a promising energy storage devices for powering hand-held and portable electronic systems/consumer electronics, Hybrid Electric Vehicles, and Electric Vehicles. The swelling and gassing of the LIC, when subjected to abuse conditions, is still a critical issue concerning the safe application. LIC is relatively safer than Li-ion batteries due to the absence of little or no oxygen and oxides in the cell, limited lithium deposition, and quick energy release. This features has made LICs less prone to thermal runaway when abused. There have been very few studies on the LICs safety but they have been very brief and do not investigate the entire range of safety issues. However, it is imperative to carry out thorough investigation that characterizes the safe operation of LICs. To further investigate the safety of LIC for commercial applications, comprehensive abuse tests were conducted on LIC 200F pouch cell type with voltage ranging from 3.8V to 2.2V developed by General Capacitors LLC and their responses were studied. The investigated cell has a specific energy and specific power to be 14Wh/kg and 6kW/kg respectively. In this study, different types of abuse testing were performed on LIC 200F specification and their result showed differences in response due to different types of abuse conditions. The overcharge, over discharge, external short circuit, crush (flat plate and blunt), and nail penetration test were performed on the cell. The thermal characterization of the cell heat generation, thermal stability and ability to withstand high temperature (150ºC) limit without resulting to thermal runaway was also studied.

Figure 1
Infrared Thermography and Electrochemical Analysis to Study the Effect of Coating Defects
Authors: David Lamuel , Ruther Rose Emily , Sheng Yangping , Wood Marissa , Li Jianlin , Rupnowski Peter , Ulsh Michael , Daniel Claus , Wood David L
Published: February 2020

Evaluation of electrode coatings using in-line non-destructive techniques and understanding the effect of electrode manufacturing defects on lithium-ion battery (LIB) performance is vital to the quality control process and key to reduce the scrap rate during cell manufacturing. In this regard, it is vital to quantify the effect of various defects that are generated during electrode coating process (Layered NMC532 cathode in this study) on LIB performance. To this end, we demonstrate defect detection and porosity measurement using IR thermography and thickness measurement using a laser technique at high line speeds. We show the comparative effects of different defects that were intentionally generated such as agglomeration, pinholes, and non-uniform coating on LIB performance in full coin cells and large pouch cells. The results show that the electrodes with more coated/non-coated interfaces had greater capacity fade than baseline electrodes at high current densities and that pinholes and agglomerates did not affect the performance adversely. In conclusion, these types of characterization of control samples shows the importance of monitoring and early detection of the electrode defects during the coating process for minimization of cell rejection rates prior to fabrication and formation cycling.

Acknowledgement: This research at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) under contract DE-AC05-00OR22725, was sponsored by the Office of Energy Efficiency and Renewable Energy (EERE) Vehicle Technologies Office (VTO) (Deputy Director: David Howell) Applied Battery Research subprogram (Program Manager: Peter Faguy).
NON-Dimensional Analysis of the Critical Condition of LI-ION Battery Thermal Catastrophic Failure
Authors: Huang Peifeng , Wang Qingsong
Published: February 2020

Lithium ion battery is the most popular used portable energy storage technology due to the relatively high energy density. While the thermal instability induced safety concern impede the pace of marching large application, which has no tolerance for the catastrophic failure. At off-normal operation, one or more side-reactions would become the main factor induce continual temperature elevation, which in turn accelerate the reaction rate and possibly lead to catastrophic thermal failure. There is divergence point between runaway behavior and normal thermal failure, which can be used to estimate whether battery can get catastrophic failure. This critical condition also can be used to explain and predict the thermal runaway propagation between cells. In this study, we focused on the interest of the thermal critical condition that leaded by one or more side-reactions using non-dimensional analysis method. The reactions used Arrhenius approximation: R=Acnexp(-E/RT). Through nondimensionalization of energy balance equation, nondimensional critical parameters such as critical criterion, critical temperature were obtained. And the nondimension stationary energy balance equations of battery thermal failure under Semenov model and Frank-Kamenetskii models were employed:ψf(θ)=θ, d2θ/dρ2+jdθ/ρdρ+δf(θ)=0. These critical parameters shows the critical condition of battery catastrophic condition correlates with cell's configuration, size and thermal characteristics of side-reactions. Under the boundary condition of two thermal abuse models (Semenov, Frank-Kamenetskii), the critical criterion (ψ, δ), critical temperature distribution (θ) and delay time of thermal runaway (τ) were analyzed in different cell deformation, capacity and thermal characteristics of side-reactions. These critical parameters are also calculated according to the thermal characteristic parameters from literature, and the results compared with the computational analysis and experiment works in literature.
Comprehensive Investigation on the Thermal Stability, Biodegradability and Fire-Induced Hazards of Pyrrolidinium-Based Ionic Liquids
Authors: Eshetu Gebrekidan Gebresilassie , Jeong Sangsik , Bertrand Jean-Pierre , Pandard Pascal , Marlair Guy , Passerini Stefano
Published: February 2020

One of the viable option to meet the stringent safety requirements of large-format LIBs is to replace the existing highly flammable/combustible, state-of-the-art organic based, electrolytes with safer ones. In this regard, the use of room temperature ionic liquids, RTILs, as advanced electrolytes in electrochemical energy storage devices has been one of the most enticing and emerging option. Though some imidazolium and chiefly pyrrolidinium based ILs are hailed as safer electrolytes, overcoming the limitations imposed by the highly volatile/combustible carbonate based electrolytes, the full scale and precise appraisal of their global (thermal stability, biodegradability, fire-induced) safety levels under abuse conditions remain to be fully addressed.

With the aim of providing the requested level of information on the safety aspects of ILs, we embarked on a detailed investigation of the short and long term thermal stability, combustion behavior and biodegradability tests of various pyrrolidinium-based ILs, synthesized in our laboratory. ILs enlisting the effect of alkyl chain length, [Pyr1A] + (A=3-10), anion, Pyr14 (TFSI, FSI and BETI), cation, [Pyr14]+/ [Pyr12O1]+ [TFSI] and salt addition (e.g. LiTFSI/Pyr14TFSI) were methodically investigated. Through the use of myriad of techniques, i.e. ramped/isothermal thermogravimetric analysis, oxygen bomb calorimetry and multi-purpose fire propagation apparatus (FPA, ISO12136), key parameters governing the thermal and fire induced hazards such as ease of ignition, heat release rate, effective heat of combustion and fire induced toxicity (CO, Soot, THCs, SO2, HF, NO, N2O, and HCN) were determined. A number of biodegradability tests including Modified Sturm, Manometric Respirometry, and Zahn-Wellens/EMPA were conducted. The thermal stability,combustion and biodegradability tests of pyrrolidinium - based ILs are specific to the nature of the anion, cation, alkyl chain length as well the addition of lithium salt.

In general, our detailed study provides a new systematic approach towards understanding the thermal stability, biodegradability and fire-induced hazard evaluation of large families of pyrrolidinium based ILs as well as access to data needed for a performance based approach of the evaluation of their safety benefits.
Nanoporous UHMWPE Membrane Separators for Explosion-Proof Rechargeable Batteries
Authors: Li Runlai , Gao Ping
Published: February 2020

This article reports the synthesis of a new nanoporous UHMWPE membrane separator that exhibits a three-fold increase in tensile strength upon a thermally-induced pore closure. High-performance biaxially oriented nano-porous ultra-high molecular weight polyethylene (UHMWPE) membranes with tensile strengths greater than 100 MPa and a volumetric porosity over 60% were prepared. These membranes exhibit two melting endotherms at 130 and 150 °C, respectively. Annealing of the nanoporous membranes under lateral dimensional constraints 145 °C for 7 seconds leads to the formation of surface-pore-free toughened films with a 350% increase tensile strength. This drastic increase in tensile strength is due to the melting induced recrystallization of kebab crystals and densification of membrane in the thickness of the film. The rapid pore-closing functionality accompanied by the accompanied toughness enhancement makes these membranes ideal for use as explosion-proof membrane separators.

Figure 1
Influence of the Temperature on the Electrochromic Properties of Complementary and Symmetrical WO3//NiO Devices
Authors: He Yingchun , Da Rocha Mathias , Diao Xungang , Rougier Aline
Published: February 2020

Electrochromic smart windows benefits include among others energy efficiency and indoor comfort [1]. However, on a daily use, the temperature is a key factor that may affect the device durability. Among materials, WO3 and NiO thin films are often combined for the realization of electrochromic devices with high color efficiency, short switching time, low cost and good stability [2]. Nevertheless, in the literature, the influence of the temperature is scarcely addressed [3].

In this study, the influence of temperature between 80 °C and -40 °C on the EC properties of WO3 and NiO based devices either in complementary WO3/electrolyte/NiO or in symmetrical structure WO3/electrolyte/WO3 and NiO/electrolyte/NiO, is discussed. WO3 and NiO thin films were deposited on ITO coated glasses (~25Ω/□) by reactive direct current (DC) magnetron sputtering. Laminated devices were prepared using lithium based composite polymer gel. The electrochromic properties of complementary devices and symmetrical devices were characterized in temperatures, both after storage for few hours and upon cycling. As a general trend, the device capacity decreases in low temperature and increase in high temperature, while intermediate cycling at room temperature shows slight degradation above 45 °C, and good recovery after cycling at low temperature (T < 0 °C). Interestingly, symmetrical devices behave differently in respect of NiO or WO3nature. In this presentation, further investigations on the evolution of the EC behavior with temperature will be discussed.

References

[1] C. G. Granqvist, Electrochromics for smart windows: Oxide-based thin films and devices, Thin Solid Films 564 (2014) 1–38

[2] H. Moulki, D.H. Park, B.K. Min, H. Kwon, S.J. Hwang, J.H. Choy, T. Toupance, G. Campet, A. Rougier, Electrochimica Acta, 2012, 74, 46

[3] M. Da Rocha, A. Rougier, Electrochromism of non-stoichiometric NiO thin film: as single layer and in full device, Applied Physics A, 2016, 122:370
Near Infrared Selective WOx-Based Electrochromic Devices Regulated By Charge Transfer Impedance at the Counter Electrode
Authors: Pattathil Praveen , Scarfiello Riccardo , Giannuzzi Roberto , Cozzoli P. Davide , Manca Michele
Published: February 2020

The realization of electrochromic (EC) devices capable of achieving independent control over the visible and near infrared regions of the solar spectrum still remains an unmet key target in the perspective of making EC glazings really attractive for the next generation of advanced dynamic building facades.

We report on the fabrication of a set of EC devices embodying engineered nanostructured electrodes made by 1D high aspect-ratio tungsten oxide nanocrystals having a specifically controlled crystal structure, which have been prepared by a suitable non-hydrolytic route.

They allow for widely tuning of the spectroelectrochemical response, which closely matches the solar spectrum, and for selectively controlling the sunlight transmission over the near-infrared to visible range.

These systems can be finely regulated through an appropriate control of two fundamental electrochemical processes occurring at the interface between the nanostructured EC electrode and the electrolyte, namely, (i) the capacitive surface charging/discharging, which is responsible of the optical density modulation in the near-infrared range at relatively low applied potentials, and (ii) the faradic current-driven Li+ insertion/deinsertion, which allows for a remarkable modulation of the visible absorption at higher potentials.
(Invited) Conjugated Polymers in Redox Active Devices: Electrochromism As a Case Study
Authors: Reynolds John R
Published: February 2020

Conjugated polymers provide a unique encompassing set of structurally tunable optical, electronic transport, and redox properties that allows their present and potential use in a host of applications which span, field effect transistors, light emitting diodes, solar cells and photodetectors, electrochromism, along with batteries and supercapacitors. Processing of these materials is carried out using a variety of solution methods including spin-coating, spray-coating, blade-coating, slot die coating and ink jet printing. In this lecture, we demonstrate how the optical absorbance spectra of electron-rich pi-conjugated polymers can be tuned to yield electrochromic materials of all colors that can be switched to highly transmissive forms as desired for absorptive/reflective (display type) and absorptive/transmissive (window type) devices. We will demonstrate how structural design and synthesis of fully conjugated polymers, along with mixing in polymer blends, has been used to complete the color palette of electrochromic polymers (ECPs) needed for subtractive color mixing. Colorimetric tuning (using the L*a*b* color space) using a combination of electron rich and poor units, in conjunction with employing subtle changes in steric strain or relaxation, allows for the enhancement of the neutral form color vibrancy, and the transmissivity of the oxidized forms. We have developed a set of fast switching, high contrast black and brown ECP blends. We use these brown blends to demonstrate the attractiveness of ECPs in window-type electrochromic devices (ECDs) as active materials in color changing eyewear.
(Invited) Inkjet Printed Multifunctional Smart Windows
Authors: Cai Guofa , Lee Pooi See
Published: February 2020

Electrochromic smart windows that are able to dynamically control the light and heat transmission into a building have attracted intense interests in the field of green building. However, currently external energy consumption is required for electrochromic smart windows to change their optical properties such as transmittance, reflectance and absorption. How to recycle the energy expended and finely integrate the multifunctional smart window are still challenging at present. With our earlier established work on the various of electrochromic nanomaterials such as NiO, WO3 on transparent conductors such as ITO, FTO, silver grid/PEDOT substrates, the importance and progresses of multifunctional smart window have been highlighted.1-4 We extended our efforts on large size multifunctional smart windows (more than 300 cm2) fabricated by inkjet printing technique which is one of the low cost and solution processible methods. The assembled electrochromic windows exhibit outstanding performance including large optical modulation, high coloration efficiency, fast switching and excellent bistability. The designed multifunctional smart window can be used as typical electrochromic window as well as energy-storage device. The smart window is able to change its color to dynamically control the light and heat into a building and store the energy in the day time, and then releases the stored energy to power other electronic devices at night. Moreover, we can monitor the level of stored energy in the window via the visually detectable reversible color variation. The reported multifunctional smart window represents a leap towards the realization of fascinating and energy-efficient smart green building.

References (1) Cai, G.; Wang, X.; Cui, M.; Darmawan, P.; Wang, J.; Eh, A. L.-S.; Lee, P. S. Nano Energy
2015, 12, 258. (2) Cai, G.; Wang, J.; Lee, P. S. Acc. Chem. Res.
2016, 49, 1469. (3) Cai, G.; Darmawan, P.; Cui, M.; Chen, J.; Wang, X.; Eh, A. L.-S.; Magdassi, S.; Lee, P. S. Nanoscale
2016, 8, 348. (4) Cai, G.; Darmawan, P.; Cui, M.; Wang, J.; Chen, J.; Magdassi, S.; Lee, P. S. Adv. Energy Mater.
2016, 6, 1501882.