bluuebunny/crossref_metadata_2025 huggingface dataset:
A General Theory of Electrochemistry
Authors: Nilsson Bruno
Published: December 2020

The electrochemical charge transfer reaction at an electrode/electrolyte interface occurs within close distance from the electrode surface. There is a delicate balance of forces between electrons in the electrode and electrode ions within the electrolyte, and forces between the ions themselves, in this region. Since ions have an electrical charge, a corresponding electrical field is present, which in turn gives rise to the electrode potential. An external current applied to the electrode will affect the distribution of ions, the electric field, and, ultimately, the electrode potential.

This report presents a new electrochemical theory that provides a detailed and accurate description of the electric field and charge distributions associated with the charge transfer reaction, together with their relation to time, electrode voltage, and electrode current. With this foundation, it is possible to establish and formulate the basic electrochemical properties of the electrochemical cell.

The core of the theory is a partial differential equation that models the electric field in close vicinity of the electrode surface based on fundamental natural constants and specific boundary conditions. The underlying basic equation was initially derived in an attempt to explain and describe the phenomenon of Induced Polarization, which technique is effectively employed by mining companies in the large-scale search for mineral deposits.

To demonstrate the general validity of the theory the well-known Butler/Volmer and Nernst’s equations are derived.

The theory also permits the accurate modeling of dynamic, or non-equilibrium properties, like the voltage variation with time from the moment an electrode is dipped into an inert electrolyte. To assess the accuracy of the modeling, experiments were carried out where a zinc electrode was dipped into a sodium sulfate electrolyte. The electrode voltage was measured over a 5 to 640 sec time span and would typically be within 5 mV of the predicted value.

The electrode voltage was also derived from initial contact with an electrolyte containing the electrode ions until equilibrium was fully established - ending up in agreement with the predictions of Nernst’s equation.

The theory also permitted the derivation of the complex impedance of the electrode/electrolyte interface reaction. A comparison with experimental data was carried out, whereby the complex impedance of a copper electrode in contact with nine different concentrations of copper sulfate/sulfuric acid electrolytes was measured. The fit with the theory was typically within 2% over the entire 0.07 to 2400 Hz measurement range. The best fit with the experimental data allowed in turn the exchange current and the electric field distribution thickness to be determined as functions of concentration.

(Preprint full report: https://ecsarxiv.org/8njbr/ )
Characterization of Recombinant Maintenance DNA Methyltransferase (Dnmt1) and Application to DNA Methylation Analysis
Authors: Yoshikawa Ryota , Iida Yasuhiro
Published: December 2020

A change doesn't occur to base sequence of DNA in the process of the human development. However, one fertilized egg differentiates into cells with sixty trillion of abundant individuality. The reason is DNA is methylated. The DNA methylated correctly is necessary for correct differentiation. Aberrant methylation induce various diseases including cancer, mental disorder and lifestyle disease.Elucidating essential of diseases needs analyzing methylation of DNA.Various DNA methylation analysis methods have been developed, among which bisulfite sequencing (BS-seq) is common.BS-seq has problems such as low sensitivity, which can not analyze cell types with insufficient sample amount, and may miss specific methylation of individual cells because it is an averaged data of cell population.Conventional BS-seq, hydroxymethylation (hmC), which is an intermediate of demethylation, is detected as methylation (mC). Since hmC is not recognized as mC in vivo, conventional BS-seq can not perform accurate DNA methylation analysis.New analytical methods are needed to assess pure DNA methylation even from small numbers of cells, such as single cells. In this study, we aim to develop a novel methylation analysis method that enables accurate methylation to be performed even with a small amount of DNA by repeating amplification and methylation of DNA using PCR and DNA (cytosine-5)-methyltransferase 1 (DNMT1).
Magnéli Phase Ti9O17- Catalyst Support Materials for ORR
Authors: Masud Jahangir , Thakare Jivan , Aulich Ted , Mann Michael , Zhao Julia Xiaojun
Published: December 2020

The durability of catalysts in polymer electrolyte membrane fuel cells (PEMFCs) is an important issue that must be addressed before their commercialization since catalyst durability directly reflects the life and cost of fuel cell power-generation systems [1]. Although many factors could play a role in the mechanism of catalyst degradation, the major contributors are believed to be i) dissolution of Pt and re-deposition (Ostwald ripening), ii) coalescence via crystal migration, and iii) detachment of Pt particles from the carbon support [2]. Among these, Pt detachment is strongly affected by the corrosion of the carbon support materials. Conventional carbon blacks, such as Vulcan XC72, are superior catalyst-support materials because of their cost and physicochemical properties. However, carbon is not stable based on thermodynamic considerations under the cathode conditions in a PEMFC:

C + 2H2O → CO2 + 4H+ + 4e− E0 = 0.207 V vs. RHE

Although this reaction proceeds slowly at potentials <0.8 V in a PEMFC [3], corrosion reactions are significantly accelerated under high potential conditions. Therefore, alternative catalyst-support materials that are highly oxidation-resistant are necessary. In order to improve the stability of the catalyst support, considerable work has been done over the past few decades on non-carbon support materials [4].

In this presentation, we have focused on oxygen-deficient, sub-stoichiometric titanium oxide (TinO2n−1, known as Magnéli phase) as a potential oxidation-resistant cathode catalyst support in PEFCs. This leads to improving specific activity for the oxygen reduction reaction (ORR) due to the formation of Pt–Ti alloy particles on the TiOx support, as well as the improve dispersion of Pt due to the deposition of smaller catalyst particles. The Magnéli phase Ti9O17 is synthesized and characterized (Fig. 1) by XRD. The Pt/Ti9O17 will be synthesized, and the ORR activity and stability will be investigated. A comparative study will be performed to those of a conventional Pt/C catalyst.

References:

Chem. Rev., 107, 3904 (2007)

Top. Catal., 46,285(2007)

ECS Trans., 1 (8), 3 (2006)

J. Mater. Chem., 19, 46 (2009)

Figure 1
High-Throughput Screening of Hydrogen Peroxide (Electro)Catalysts Using Scanning Electrochemical Microscopy (SECM)
Authors: Zhao Yuanya , Kromer Matthew , Adams Jason , Flaherty David , Rodríguez-López Joaquín
Published: December 2020

Hydrogen peroxide (H2O2) is a powerful, versatile and environmentally benign oxidant that has gained relevance in industrial settings. Direct synthesis of H2O2 from O2 and H2, which is a method with low pollution and on-site production at potentially low cost, has attracted great interest. To realize this synthetic process, catalysts of high efficiency need to be developed to facilitate the reaction. In this study, scanning electrochemical microscopy (SECM) methods were used to conduct high-throughput screening of bimetallic nanoparticle catalysts (consisting of Au, Pt, Ni, etc.) for H2O2 generation from direct synthesis. In order to achieve high-throughput analysis, samples with multiple catalysts were fabricated. We used photolithography to produce wells that confined catalyst spots of a library of materials. Gold nanoparticles (AuNPs) were dispensed into these wells with a microdispenser, leaving the same amount of AuNPs at each spot. Droplets of corresponding metal salt solutions were added into the wells and then annealed to form bimetallic catalyst spots. The morphology and composition of fabricated spot arrays were characterized with SEM, TEM and EDS.

SECM measurements were performed to study the catalytic reactivity of the catalyst spots for H2O2 direct synthesis. From an electrochemical point of view, the entire process of H2O2 direct synthesis from H2 and O2 can be split into two half reactions, oxygen reduction and hydrogen oxidation. The first half reaction, oxygen reduction reaction (ORR), is a two-electron process reducing O2 into H2O2. The second half reaction, hydrogen oxidation reaction (HOR), converts H2 to protons. Only when a catalyst exhibits outstanding catalytic reactivity towards both two reactions, does it catalyze H2O2 direct synthesis efficiently in a thermocatalytic system. The catalytic reactivity for the two half reactions was investigated separately in a high throughput manner by SECM as the technique acquired information from the entire spot array in one scan and revealed catalytic performance for each spot in the array. SECM images were obtained to visualize catalytic reactivity of the spot array.

Finite element analysis simulation was done in COMSOL Multiphysics to acquire theoretical values for SECM experiments. The ultimate goal of this study is to identify a catalyst of a specific composition with the best catalytic reactivity for overall H2O2 direct synthesis. Such catalyst can be used in industrial H2O2 production to improve production efficiency and to reduce cost.
Theoretical Analysis of Photo- and Electrochemical Properties of Anatase-Type TiO2 Nanoparticles
Authors: Juhasz Gergely
Published: December 2020

Oxide nanoparticles, like TiO2 nanoparticles are often applied in electrodes and photocatalytic systems. The morphology and shape of these nanoparticles can be easily tuned with experimental conditions, which raises the question how much the electro- and photochemical properties are affected by the nanoparticle geometry.

We studied the electronic states around the bandgap in anatase-type TiO2 nanoparticles of different shapes with (101) and (001) facets using Density Functional-based Tight Binding (DFTB) method. Previous calculation has already shown that most orbitals of the valence and conduction bands forms delocalized band-like orbitals, however there are a significant number localized states at the lower at edge of conduction band, too. These trapping sites may play important role in electrochemistry when located on the surface of the nanoparticle.

Photochemical properties however depend on optical transitions between electronic states with proper symmetry, and mostly dominated by delocalized states of atoms in the bulk. In this talk we analyze the optical spectra (see Figure 1) on the nanoparticles and compare it to the electrochemically important surface trapping

Figure 1
Buffer Pk
a Impacts the Mechanism of Hydrogen Evolution Catalyzed By a Cobalt Porphyrin-Peptide
Authors: Alvarez-Hernandez Jose L. , Sopchak Andrew E. , Bren Kara L.
Published: December 2020

The effect of buffer pK
a on the mechanism of electrochemical hydrogen evolution catalyzed by a cobalt porphyrin peptide (CoMP11-Ac) at constant pH is presented. The addition of buffer to CoMP11-Ac in water and KCl leads to an enhancement of the catalytic current of up to 200-fold relative to its value in the absence of a buffer. Two distinct catalytic regimes are identified as a function of the buffer pK
a. In the presence of buffers with pK
a ≤ 7.4, a fast catalysis regime limited by diffusion of buffer is reached. The catalytic half-wave potential (E

h
) shifts anodically (from −1.42 to −1.26 V vs Ag/AgCl/KCl(1M)) as the buffer pK
a decreases from 7.4 to 5.6, proposed to result from fast Co(III)-H formation following the catalysis-initiating Co(II/I) reduction. With higher-pK
a buffers (pK
a > 7.7), an E

h
= −1.42 V, proposed to reflect the Co(II/I) couple, is maintained independent of the buffer pK
a, consistent with rate-limiting Co(III)-H formation under these conditions. We conclude that the buffer species pK
a impacts catalytic current and potential and the rate-determining step of the reaction.
Application of Polymer Electrochemistry in Interconnects and its Components
Authors: Budhraja Vinay , Chudasama Rupesh , Stirn Jarvis , Musaramthota Vishal , Hallstrom Eric , Bentz Jed
Published: December 2020

Electroplating of metals is a commercially viable industrial technique which is used in the fabrication of electrical components such as contact pins, waveguide, spring probes etc. for multiple applications including defense, semiconductor, rail, space etc. The base material of these components is typically nickel-silver, copper, copper alloys or brass which is further plated with nickel and gold to reduce contact resistance. Utilization of these metals has several disadvantages such as high density, sensitive to humidity, risk of corrosion, high processing and shipping cost and material waste at high frequency. Henceforth efforts are being investigated to mitigate these challenges via transitioning to polymeric material system. In this work, spring probes and waveguides have been fabricated using polymers such as PEEK, PEI, ABS and Nylon 12 and electroplated with copper, nickel and gold followed by mechanical and electrical characterization. The spring probes components underwent electrical and mechanical tests such as Force- Deflection-Resistance (FDR), Life Cycle Tests (LCT) and high current test (HCT), cross sectioning, SEM and X-Ray CT scanning. Spring probes were further tested against humidity, porosity and salt fog using internationally recognized standard test methods to check the performance of corrosion resistance.Spring probes showed high performance in FDR and LCT with a high current carrying capability in HCT. Spring probes passed all corrosion tests such as humidity, salt-fog, porosity, thermal shock and fretting corrosion.

The waveguides on the other hand were additively manufactured and underwent tests for return and insertion losses along with phase balance testing that exhibited comparable performance when compared to traditional manufacturing methods. The lead time and part cost was significantly reduced using 3D Printing demonstrating a viable route for manufacturing.

Furthermore, an electrical component made with a plastic body has a lower shock hazard than one made with metal. Metallic body is susceptible to a great degree of electrical interference, leading to more noise than components made with plastic because of higher parasitic losses. Providing contact continuity during shock and vibration is critical for harsh environments but it may not be sufficient if the quality of transmitted signal is not adequate. At high frequencies, current flows up to a skin depth and the remaining part of the body does not participate in the conduction process. In such situations, the parts made up of polymer described herein are a solution to the problem.

Figure 1
Electrochemical Sensor for the Detection of Nitrite Based on PEDOT and Hollow Gold - Palladium Nanoparticles
Authors: Lucero Gisella Liliana , Bund Andreas
Published: December 2020

Nitrites are chemical compounds commonly used as additives in food industry, especially to improve organoleptic properties of meat and prevent its degradation. According to the World Health Organization, nitrite concentrations exceeding 3 mg/L in drinking water and wastewater are hazardous for the environment and human health [1]. Nitrites can react with hemoglobin and form methemoglobin which blocks oxygen transport and generates cyanosis in infants. Also, N–nitroso compounds, potentially carcinogenic products, can be formed by the reaction of nitrites with amines [1]. For those reasons, monitoring the level of nitrite in water is extremely important.

Nitrite ions are traditionally detected and quantified by colorimetry, chemiluminescence and chromatographic and spectrophotometric techniques. However, these techniques are time consuming, require complex devices or the pretreatment of the samples to prevent interferences and moreover, imply the use or the production of some toxic reagents. Electrochemical sensors based on nanomaterials like graphene, metal nanoparticles and conducting polymers have also been used for the detection of nitrite [2,3]; however, to the authors´ best knowledge, sensors based on PEDOT and hollow bimetallic nanoparticles have not been tested as potential material for this purpose.

In this work, hollow AuPd nanoparticles were produced by galvanic replacement from cobalt cores. The nanoparticles were analyzed by SEM, EDX and TEM/STEM. Results revealed the hollow structure of the nanoparticles (size 30-45 nm, Fig. 1). It was confirmed that they contain Au and Pd. EDX was performed to evaluate the elemental profile through the nanoparticle. Hollow AuPd nanoparticles, previously centrifuged and resuspended in water, were co-deposited from a solution of the monomer EDOT, the surfactant SDS, LiClO4 at potentiostatic conditions. The analytical performance of the composite material for the detection of nitrite was evaluated by differential pulse voltammetry (Fig. 2) in the range of 50 to 250 µM. The sensitivity of the sensor was 0.04 +/-0.01 µA µM-1.

[1] World Health Organization, Guidelines for Drinking – water Quality. (2017) 398pp. Available from: https://www.ncbi.nlm.nih.gov/books/NBK442376/

[2] Fu L., Yu S., Thompson L. And Yu A. RSC Adv. 5 (2015) 40111.

[3] Li G., Xia Y. Tian Y., Wu Y., Liu J., He Q. and Chen D. J. Electrochem. Soc. 166(12) (2019) B881.

Figure 1
Fe(III)-Exchanged Zeolite As Efficient Electrocatalysts for Electrodegradation of Congo Red Dye
Authors: Bencheqroun Zeineb , Ferreira Marta , Sahin Nihat , Rombi Elisabetta , Zaitan Hicham , Nawdali Mustapha , Fonseca Antonio M. , Parpot Pier , Neves Isabel C.
Published: December 2020

The role of the nanostructured iron catalysts hosted by different type of zeolite structures (NaY and ZSM5) on the electrochemical degradation of Congo Red dye (C32H22N6Na2O6S2) was investigated. Here, the nano-iron zeolite catalysts with high surface areas (up to 853 m2 g-1) were prepared by ion-exchange method1 serving tunable particle size and acidity that is highly sensitive to the local reaction environment at the electrode surface. The structural and morphological analysis was carried out using scanning electron microscopy (SEM), X-ray diffraction and N2-sorption techniques. In order to clarify the electrocatalytic trend observed by constant potential electrolysis, we further considered the acidity properties of the zeolites determined by microcalorimetric measurements. Moreover, it was noted that the presence of NH4
+, H+ and Na+ ions in the case of ZSM5 zeolite allows the rearrangement of the iron-zeolite architecture, resulting in a more favorable stabilization of the degradation process as a function of the production rate. Compared with the FeNaY catalysts, the FeZSM5 catalysts (Fe(Na)ZSM5, Fe(H)ZSM5 and Fe(NH4)ZSM5) exhibited excellent activity and stability, with a maximum dye degradation around 64% on the Fe(H)ZSM5 catalyst. This work, revealing the synergetic interactions between the acid sites of the zeolite and the catalytic active sites, provides a new route for the development of electrochemical sensing low-metal content zeolite structures.

Acknowledgements:

This work was conducted in the framework of the BioTecNorte projects: NORTE-01-0145-FEDER-000004, PTDC/AAGTEC/5269/2014, UID/QUI/00686/2013, and UID/QUI/0686/2016. Z. B. is grateful for ERASMUS research grant.

Reference:

1. M. Ferreira, F. Pinto, O. S. G. P. Soares, M. F. R. Pereira, J. J. M. Órfão, J. L. Figueiredo, I. C. Neves, A. M. Fonseca, P. Parpot, Chemical Engineering Journal, 228 (2013) 374.
Quantum Chemical Calculation of Lithium Polysulfide in EMI-Tfsi Solution: SMD(Universal Solvation Model Based on Solute Electron Density and a Continuum Model of the Solvent) Model
Authors: Yamamoto Masahiro , Sawada Yuma
Published: December 2020

One of the problem of the sulfur-based electrode for the all-solid-Lithium-Sulfur battery cells is the chemical (or electrochemical) decomposition of lithium polysulfide Li2S
n
. Kinoshita et al have shown that the EMI-TFSI (1-Ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide) ionic liquid contained all-solid-Lithium-Sulfur battery has a good battery performance. In this study we have calculated the quantum chemical calculation of lithium polysulfide Li2S
n
. in continuum which has the dielectric constant and optical constant is the same as EMI-TFSI ionic liquid. The solvation effect is included by the SMD (Universal Solvation Model Based on Solute Electron Density and a Continuum Model of the Solvent) model. The Austin-Frisch-Petersson functional with dispersion is used in the calculation. From the total energy difference of the enthalpy of the reaction 2Li+ + Sn → (LiSn)2+, 2Li+ + Sn
2- → LiSn, and decomposition reactions. The enthalpy of the reactions have been compared with the experimental results given by Uchimoto and Yamamoto.

Reference

[1] S. Kinoshita, K. Okuda. N. Machida and T. Shigematsu, J. Power Sources, 269, (2014) 727-734.

[2] Y. Uchimoto, K. Yamamoto, private communication
(Invited) Solid-State Chemistries Stable with High-Energy Cathodes for Lithium-Ion Batteries
Authors: Mo Yifei , Nolan Adelaide M , Liu Yunsheng
Published: December 2020

The continued improvement in operating time and lifetime of electric vehicles and portable electronic devices requires higher energy density lithium ion batteries. The energy density of lithium-ion batteries can be increased by implementing high-voltage cathodes, but these cathodes are reactive and unstable during cycling with the electrolyte. To design coatings or solid electrolytes that can stabilize these cathodes, an understanding of how different chemistries interact with high-voltage cathodes is critically needed. We systematically evaluate the thermodynamic stability of a broad range of solid-state chemistries with common cathodes (1). A materials trade-off is found in that materials stable with lithiated cathodes are often unstable with delithiated cathodes, which limits the possible choice of materials stable throughout the cycling voltage. These computational findings reaffirm previously demonstrated coating and solid electrolyte chemistries and suggest that several new chemistries, including lithium phosphates and lithium ternary fluorides, are promising solid-state chemistries stable with high-voltage cathodes. Our study provides guiding principles for designing coating and solid electrolyte materials with long-term stability with high-voltage cathodes for lithium-ion batteries.

(1) Nolan et al., ACS Energy Lett. 2019, 4, 2444–2451
(Invited) Kinetic Isotope Effect As a Tool to Investigate the Oxygen Reduction Reaction on Pt-Based Electrocatalysts
Authors: Zenyuk Iryna V.
Published: December 2020

Oxygen reduction reaction (ORR) mechanisms on Pt electrocatalyst was investigated with kinetic isotope effect (KIE). Specifically, the rate-determining step for ORR on dispersed Pt/C electrocatalyst and polycrystalline Pt (Pt-poly) was studied. KIE is defined as the ratio of the kinetic current measured in protonated electrolyte versus deuterated electrolyte, where KIE values larger than one indicate the proton participation in the rate-determining step. We have investigated the effect of poisoning anions on the Pt on the rate determining step by assessing the KIE in perchloric (non-poisoning) and sulfuric acid-based electrolytes. The kinetics currents were calculated using both Koutechy-Levich and Tafel analysis. A KIE of 1 was observed for high loading, Pt/C (with a 40 wt.% Pt loading) and Pt-poly, thus indicating that, on 40 wt. % Pt/C and Pt-poly, the rate determining step is proton independent. We have extended the study to various carbon black supports with specific surface area ranging from 80 to 900 m2/g. When the density of Pt nanoparticles on the surface of carbon support was high, we observed KIE to be 1. However, at lower Pt nanoparticles densities the KIE was higher than one, indicating that carbon support has some impact on the rate determining step.

Figure 1
(Invited) Ionic Liquid Interlayer for Enhanced Oxygen Reduction Reaction Electrocatalyst Activity and Durability
Authors: Snyder Joshua David
Published: December 2020

After a period of dynamic advancement in oxygen reduction reaction (ORR) electrocatalyst activity, through the development of unique material nano-architectures and compositional gradients, we have seen a stagnation in the general performance metrics, especially at the membrane electrode assembly (MEA) level. We argue that in order to push past our current plateau, we must look beyond the catalyst material and develop strategies to manipulate and optimize the interface between the catalyst and the aqueous electrolyte. Here we will present our work in the development of ionic liquid interlayers, on the order of 1 nm in thickness, on nanostructured and single crystal electrocatalysts, which are found to yield significant enhancements in both ORR activity and durability. It is through the manipulation of interfacial water, due to the presence of the hydrophobic/protic ionic liquid interlayer, that a more optimal solvation of adsorbed intermediates is achieved, resulting in enhanced ORR activity, and a relative decrease in the oxophilicity of the surface, enhancing the potential dependent stability of the catalyst. Additionally, the low metal ion solubility within the ionic liquid interlayer increases the barrier for metal dissolution. We will present our analysis of the mechanism of activity and durability enhancement as well as demonstrate the unique advantages of ionic liquid interlayers in proton exchange membrane fuel cell (PEMFC) catalyst layers.
(Invited) Investigations on Sulfide Solid-Electrolyte Cathode Interfaces
Authors: Nanda Jagjit , Self Ethan Craig , Yang Guang , Brahmbhatt Teerth , Delnick Frank M.
Published: December 2020

Advances in solid electrolytes (SEs) with superionic conductivity and stabilized electrode-electrolyte interfaces are key enablers for all solid-state batteries (SSBs) to meet the energy density and cost targets for next generation batteries for electric vehicles. Compared to their ceramic counterparts, sulfide- and thiophosphate-based electrolytes offer several key advantages, including (i) exceptionally high ionic conductivities up to 10-2 S/cm (comparable to non-aqueous liquid electrolytes) as reported for Li10GeP2S12 and Li9.54Si1.74P1.44S11.7Cl0.3, (ii) availability of low temperature and inexpensive synthesis routes to produce glass, glass-ceramic, and crystalline structures, and (iii) soft mechanical properties, which facilitates material processing. Among the drawbacks, sulfides have a narrow electrochemical window, hence limited electrochemical stability against Li-metal and cathodes and poor chemical stability including high sensitivity to moisture. Despite an intrinsic narrow thermodynamic range, most SEs rely on kinetic stability based on slow growth of the interfacial layer that has reasonable ionic conductivity and very low electronic conductivity. In addition to the thermodynamical instability, significant mechanical stresses develop in SE due to (i) volume changes of the electrode material during repeated lithiation (delithiation) and (ii) interface roughening from side reactions upon extended cycling. This effect often termed as “chemo-mechanical effect” results in poor interfacial contact between the SE and cathode. The talk will highlight a few material based approaches towards addressing the interfacial stabilities (as mentioned above) between Li3PS4 SE and lithium-ion cathodes such as NMC. The area specific resistance (ASR) between SE-Cathode interfaces were optimized by coating cathode particles, varying stack pressure and doping the SE compositions.

Acknowledgment - This research was conducted at Oak Ridge National Laboratory, managed by UT Battelle, LLC, for the U.S. Department of Energy (DOE) and is supported by Asst. Secretary, Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (VTO) through the Advanced Battery Materials Research (BMR) Program
Preparing Microstructured Porous Garnet Electrodes By a Novel Method for All-Solid-State Batteries
Authors: Shen Fengyu , Jonson Robert , Tucker Mike C
Published: December 2020

High interfacial resistance is a bottleneck for all-solid-state batteries. Tremendous effort has been made to enhance the physical contact between the electrode (anode and cathode) and solid-state electrolyte. For example, by inserting a thin buffer layer of metal oxides, metals, polymers, or some other Li+ conductor, intimate physical contact can be achieved, resulting in a substantial reduction in interfacial resistance. However, this is only effective on Li metal anode side and the interfacial resistance on the cathode side is still high. A strategy to overcome this barrier is adoption of a porous-dense-porous tri-layer structure. The electrode-electrolyte interfacial surface area can be increased more than ten times, achieving low area-specific resistance. Microstructured porous layers, serving as electrode supports, are prepared with PMMA poreformer. In this work, a new water-based method is deployed to prepare vertical-direction pores aligned with the Li+ transfer path, in electrode supports based on LLZO garnet material. This method is environment-friendly, low-cost, and anticipated to be scalable. The pore size, volume, and depth is optimized and characterized with synchrotron tomography. The impact of the tri-layer structure on interfacial resistance on both anode and cathode is analyzed during full cell operation.
Engineered Electrode-Electrolyte Interface for Moisture-Stable, Dendrite-Free Garnet-Type Solid-State Electrolytes
Authors: Rajendran Sathish , Thangavel Naresh kumar , Mahankali Kiran , Arava Leela mohana reddy
Published: December 2020

Lithium-ion batteries (LIBs) are becoming increasingly universal energy storage systems to power most portable electronic devices and electric vehicles due to their high energy densities and long cycle life1-3. However, with increasing applications of LIBs into grid storage, an increase in the efficiency of LIBs is essential to meet today’s requirements2, 4. Solid-state batteries using garnet-type solid-state electrolytes (SSEs) are promising contenders for safe, high energy density devices due to their high lithium-ion conductivity at room temperature, wide electrochemical stability window, and the use of lithium metal anode5. However, garnet-type SSEs exhibit formidable challenges including the formation of lithium dendrites, instability in moisture containing atmosphere, and their high interfacial resistance. Although several strategies have been employed to improve the issues related to garnet-type SSE, most approaches focus on one challenge and fail to solve all other challenges. Herein, we demonstrate an engineered electrode-electrolyte interface with surface modification of Li6.5La3Zr1.5Ta0.5O12 (LLZT) garnet-type SSEs by two-dimensional hexagonal boron nitride (h-BN) nanosheets to solve the interfacial issues. Detailed spectroscopic evidence reveals that the surface modification effectively protects the LLZT from moisture-induced chemical degradation and suppresses the formation of adverse surface impurities for over 5 days in an open atmosphere. The interfacial resistance value has reduced nearly 10-fold when compared to the uncoated LLZT and exhibits stable lithium plating/stripping behavior for over 1400 hours at 0.2 mA cm-2. Advanced in-situ Raman analysis elucidates that h-BN layers remain stable during cycling and prevents the structural transformation of the garnet-type SSE at the interface.

References:

Whittingham, M. S., Ultimate limits to intercalation reactions for lithium batteries. Chemical Reviews
2014,
114 (23), 11414-43.

Etacheri, V.; Marom, R.; Elazari, R.; Salitra, G.; Aurbach, D., Challenges in the development of advanced Li-ion batteries: a review. Energy & Environmental Science
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4 (9), 3243-3262.

Armand, M.; Tarascon, J. M., Building better batteries. Nature
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451 (7179), 652-7.

Goodenough, J. B.; Kim, Y., Challenges for rechargeable Li batteries. Chemistry of materials
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22 (3), 587-603.

Jones, J. C.; Rajendran, S.; Pilli, A.; Lee, V. R.; Chugh, N.; Arava, L. M. R.; Kelber, J. A., In situ x-ray photoelectron spectroscopy study of lithium carbonate removal from garnet-type solid-state electrolyte using ultra high vacuum techniques. Journal of Vacuum Science & Technology A
2020,
38 (2), 023201.
The Effect of Li2CO3 on Mechanical and Electrochemical Behavior of Li6.4La3Zr1.4Ta0.6O12 Solid-State Electrolyte
Authors: Hu Shan , Zhao Kejie , Ni Hongwei
Published: December 2020

Li6.4La3Zr1.4Ta0.6O12 (LLZTO) is a very promising solid-state electrolyte for all solid-state battery. Due to its high ionic conductivity and chemical and electrochemical stability that can allow to use Li metal as anode with a high energy density as well as enhanced battery safety. However, there is little research to study the intrinsic mechanical properties of LLZTO which is a key factor that will influence the capacity fading and shortened lifetime of battery. In this study, we examine the effect of different densities on the elastic modules, hardness and toughness of Ta substituted LLZO solid-state electrolyte which will result the varieties of the mechanical and electrochemical performance. After annealing, the densities of the sample varied from 85% to 96% with the grain size from 3.5μm to 5.1μm. By introduction of the Li2CO3 additive, the grains become more connected and the number of pores at the grain boundaries becomes much smaller. The grain size rages from 3 to10μm. 5%-LLZTO has more strong grain boundary. It is suggested that the mechanical fracture happened during the Li plating process. Impedance of ion diffusion and electron transfer increase as density increase. Hardness decreases with increasing porosity and increasing grain size. The young’s modulus and the hardness increased from 121.9 to 138.8 Gpa and 4.54 to 11.26 Gpa for the 85% and 96% relative density samples, respectively. The results of this study reveal that the density of LLZTO was influenced by the amount of Li2CO3, so that the mechanical performance can be optimized through the selection of the microstructure, network, and properties of the active materials.
Safety Enhancement of Rechargeable Lithium Battery By Using Quasi-Solid-State Electrolyte Based on Thiol-Ene Click Chemistry
Authors: Lim Da-Ae , Park Sung-Guk , Jeong Bora , Lee Chul Haeng , Ahn Kyoung Ho , Lee Jung Hoon , Kim Dong-Won
Published: December 2020

Lithium-ion batteries (LIBs) have been dominant power sources for various applications such as mobile electronic devices, electric vehicles and energy storage systems. However, liquid electrolyte currently used in LIBs has critical drawbacks such as high flammability and leakage problem. In this regard, various electrolyte systems have been studied to replace liquid electrolyte for enhancing the battery safety while maintaining the battery performance. Among them, the chemically cross-linked gel polymer electrolytes can enhance the thermal safety of LIBs by encapsulating organic solvent in the polymer matrix. However, they usually contain a large amount of organic solvents to achieve high ionic conductivity, and side reactions may occur during the cross-linking reaction. To overcome these problems, quasi-solid-state electrolytes are synthesized through thiol-ene click reaction, since the click reaction avoids side reactions and drives fast cross-linking under mild reaction conditions. The quasi-solid-state electrolyte was applied to the lithium-ion cell composed of graphite anode and LiNi0.6Co0.2Mn0.2O2 cathode. The cell employing quasi-solid-state electrolyte exhibited the enhanced safety compared with the liquid electrolyte-based cell and better cycling performance than all-solid-state lithium batteries at ambient temperature. Our result demonstrate that the quasi-solid-state polymer electrolytes are very promising electrolytes for achieving high performance and enhancing battery safety.
AgI Electrolytes for Printable Solid-State Thermal Batteries
Authors: Lee Rose Yesl , Hopkins Emily , Tsui Lok-kun , Allcorn Eric , Garzon Fernando H
Published: December 2020

Thermal batteries are used as power sources in safety-critical electrical systems that require stability during long-term storage and reliability during high current operation when activated. AgI is an attractive material for a solid-state electrolyte for thermal batteries because of its low ionic conductivity near room temperature. It then undergoes a phase transition to a high conductivity phase above 150C. [1, 2] We have investigated the development of AgI batteries using I2 loaded carbon or PVP as a cathode material and Ag as an anode material. The electrochemical reactions for solid-state batteries in this configuration are as follows:

Ag+ + e- + ½ I2 => AgI (Cathode)

Ag => Ag+ + e- (Anode)

Overall: 2Ag + ½ I2 => AgI (DE = 0.95 V)

The batteries were first investigated as pressed pellets of Ag powder prepared by electrolysis, AgI powder, and Cabot Norit SX-Ultra activated carbon soaked in an ethanol I2 solution. Pressed pellets yielded an maximum power of 4.9 μW at room temperature and 0.6 mW above 150C, confirming the ability to extract higher power out of the cell when heated. Additive manufacturing of this electrolyte would enable the printing of thermal batteries in custom geometries for integration into small electronics devices. Pastes and processing conditions were developed for the printing of Ag, PVP loaded I2, and AgI. Additive manufacturing would also enable the printing of the higher conductivity AgI/Al2O3 composites which are difficult to fabricate by traditional clean room deposition technologies.

This project was supported by Sandia Laboratory Directed Research and Development Grant 209285. SAND2020-4499 A.

References.

[1] K. Lehovec, J. Broder, Journal of The Electrochemical Society, 101, 208 (1954).

[2] J. S. Lee, S. Adams, and J. Maier, Journal of The Electrochemical Society 147, 2407 (2000).

Figure 1. Power curves for Ag/AgI/I2 battery operated between room temperature and 160C.

Figure 1
Chromium Electroplating from Cr(III) in Deep Eutectic Solvents
Authors: Ispas Adriana , Gruia Violeta-Tincuta , Bund Andreas
Published: December 2020

Hard chromium coatings are often used to improve the wear and corrosion resistance of different tools and components. Often electrolytes based on hexavalent chromium compounds, which are highly oxidative and carcinogenic, are still used to plate hard chromium layers. A key challenge is the development of an alternative baths free of Cr(VI). Such an alternative could be chromium coatings from a Cr(III)-based electrolyte.

Over the last years alternative electrolytes besides water were studied for electroplating. One of these alternatives are the deep eutectic solvents, DES, of which ethaline is a prominent candidate. It is 1:2 molar ratio mixture of choline chloride and ethylene glycol. This DES show good solubility for various metal salts. The electrochemical potential window of most DES is typically in the range of 3 V. Ethaline has excellent physical and chemical properties, such as: it is stable under ambient conditions, easy to prepare and handle, cheap (manufactured on the M tons scale globally) and biodegradable (used as a B-vitamin in animal food), requires no additional registration for process applications, it has good conductivity and low viscosity.

This paper will discuss the electroplating of Cr layers from ethaline on steel substrates. Different concentrations of CrCl3 × 6 H2O in the DES were investigated. The influence of LiCl, NaCl, KCl, formic acid and oxalic acid in the electrolyte as well as the influence of temperature were also investigated. Furthermore, the role of deposition technique (direct current or pulsed current) and of the hydrodynamic conditions on the quality of the chromium layers were evaluated.

The electrodeposition of some µm thick and adherent chromium films was proved to be possible from ethaline. The hardness of the deposited Cr layers was up to 2500 N/mm2, depending on the process parameters.
Eutectic Mixture of Iron(III) Chloride and Acetamide — Physicochemical Properties, Chemical Speciation, and Electrodeposition of Iron
Authors: Higashino Shota , Abbott Andrew P , Miyake Masao , Ikenoue Takumi , Hirato Tetsuji
Published: December 2020

The electrodeposition of iron alloys is a significant research topic, owing to the potential applications such as corrosion/wear-resistant coatings1, magnetic thin films2, and catalyst electrodes3. Although aqueous electrolytes have been mostly used for electrodeposition, vigorous hydrogen evolution on the cathode can lead to hydrogen embrittlement and precipitation of metal hydroxides2. In addition, less noble elements such as aluminum and silicon cannot be co-deposited from aqueous electrolytes due to the limited electrochemical window.

To overcome the limitations of aqueous solutions, non-aqueous systems such as molten salts and ionic liquids have gained significant research attention. The electrochemical behaviour of iron complexes in imidazolium- and pyrrolidinium-based ionic liquids, and electrodeposition of metallic Fe was demonstrated in some liquids4,5. Many ionic liquids are, however, not viable on a practical scale.

In this study, we explored an alternative electrolyte to ionic liquids for electrodeposition of iron. A mixture of ferric chloride and acetamide is shown to give a liquid at ambient temperature. This eutectic mixture has a higher conductivity than comparable eutectics formed from either aluminium or zinc chloride. Ferric chloride disproportionates to form both anionic and cationic iron species identified using spectroscopic methods. The electrodeposition of dense metallic iron film was demonstrated.

References

N. Tsyntsaru et al., Surf. Eng. Appl. Electrochem., 48, 491–520 (2013)

G. Panzeri et al., Electrochim. Acta, 271, 576–581 (2018)

N.-C. Lo et al., J. Electrochem. Soc., 163, D9–D16 (2016).

P. Giridhar, B. Weidenfeller, S. Z. El Abedin, and F. Endres, ChemPhysChem, 15, 3515–3522 (2014).

Y. Zhu, Y. Katayama, and T. Miura, J. Electrochem. Soc., 159, D699–D704 (2012).
In-Situ Spectroelectrochemistry of Lanthanides in Molten Chloride Salts
Authors: Gakhar Ruchi , Phillips William C. , Horne Gregory P. , Pimblott Simon M. , Halstenberg Philip , Mahurin Shannon , Wishart James F.
Published: December 2020

Molten Salt Reactors (MSRs) are a potential game-changing technology for next-generation nuclear power. Although the MSR concept was demonstrated at Oak Ridge National Laboratory (ORNL) in the 1960’s, it had not gathered attention from commercial vendors until recently. A fundamental knowledge of salt chemistry, including the speciation and solubility of corrosion and fission products is central to the safe and reliable operation of MSRs. The structural properties of fused salt solutions, especially the coordination geometry around the metal ions in the melt, are intricately dependent on the melt composition and temperature. In this work, a combination of in-situ electrochemistry and optical absorption spectroscopy techniques are utilized to understand the speciation and structure of lanthanides in molten chloride salts as a function of temperature, concentration and melt composition. The spectroelectrochemistry of metal species in molten salt media can be used as a potential process monitoring technique enabling the quantitative measurement of lanthanide and actinide metals within molten salt reactors or nuclear fuel pyro-processing applications.

This work was supported as part of the Molten Salts in Extreme Environments Energy Frontier Research Center, funded by the U.S. Department of Energy (US-DOE), Office of Science, Basic Energy Sciences, at BNL, INL and ORNL under contracts DE-SC0012704, DE-AC07-05ID14517 and DE-FC02-04ER15533, respectively.
Electrochemical Techniques to Monitor the Concentration of Oxide in Molten FLiNaK Salt
Authors: Choi Suhee , Strianese Andrew R. , Simpson Michael Forrest
Published: December 2020

Molten fluoride salts have attracted interest as fuel and/or coolant for several different molten salt reactor (MSR) designs. Fluoride salts have many advantageous properties for these applications, such as high ionic conductivity, good heat transfer capacity, and high solubility for actinides. However, the impurities of the fluoride salt corrode the metals of MSR such as H2O, HF, and metal impurities. Therefore, it is important to monitor the oxides in molten fluoride salt. In this study, LiF-NaF-KF (FLiNaK) salt was used as a less toxic surrogate for FLiBe because of the toxicity of beryllium. In this work, we focused on measuring the concentration of oxide by adding Li2O in the FLiNaK salt using two electrochemical methods: cyclic voltammetry (CV) and square waver voltammetry (SWV). Moreover, after the electrochemical tests, the salts were analyzed for concentration of oxygen by LECO in order to compare with electrochemical results. We observed an oxidation peak corresponding to oxide using CV with a tungsten working electrode. Then SWV was used to measure the oxidation peak for oxide at various concentrations (0.1 to 2.0 wt.% of Li2O). SWV can measure the low concentration, because SWV is more sensitive to the oxidation current than CV through eliminating the non-faradaic current.
Anodic Behavior of MoSi2 in Molten MgCl2-NaCl-CaCl2 Containing Oxide Ions
Authors: Miyoshi Takamasa , Morishige Taiki , Takenaka Toshihide
Published: December 2020

Mg and Li are smelted by electrolysis in molten chloride, and carbon-based material is used for the anode. Carbon-based anode reacts electrochemically with oxide ions dissolved in the bath, causing oxidative consumption. Therefore, the development of the so-called inert anode is desired. The authors proposed an inert anode by forming a stable passivation film on it and investigated the anodic behavior and the conditions to form a film on MoSi2 in molten LiCl-KCl containing Li2O. In this study, the behavior of MoSi2 anode and film formation on it have been investigated in molten MgCl2-NaCl-CaCl2.

MgCl2-NaCl-CaCl2 electrolytic bath with about 1 mass% MgO was used at about 973K in an Ar atmosphere. A MoSi2 rod was used as working electrode. A Cu plate and Ag/AgCl were used as counter and reference electrode, respectively. Anodic behavior of MoSi2 was investigated by cyclic voltammetry and potentio-static electrolysis. The change in the MoSi2 surface with electrolysis was analyzed by XRD and SEM-EDX.

Fig. 1 shows a cyclic voltammogram in the bath with MgO. Anodic current density increased at about 1.6 V (vs. Mg / Mg2+) and an anodic current peak appeared at about 1.8 V (vs. Mg / Mg2+). After the peak, the anodic current density sharply decreased. Since this anodic current peak was not seen without addition of MgO, it was indicated that the passivation phenomenon occurred in the bath with MgO.

Fig. 2 shows the SEM image and element distributions of the cross-section of MoSi2 after potentio-static electrolysis for 4h at 3.1V (vs. Mg / Mg2+) in the bath with MgO. A passivating film of about 3 µm-thick was seen on the anode surface, and Si was found on it. Mg and O were concentrated in the passivation film, and SiO2 and MgSiO3 were detected by XRD. From the quantity of electricity during the potentio-static electrolysis, the thickness of the passivation film and the weight change, the current contributions for the passivation film formation, and for Mo dissolution were about 2% each, while about 96% of the electricity was shown to be spent by other reactions. Considering the electrolysis condition, 3.1V (vs. Mg/Mg2+), most of the current seemed to be used for the gas generation. It is concluded that MoSi2 is potential for the inert anode in molten chloride-containing oxide ions.

Figure 1