bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of Titanium Disulfide Cathode Additive in the Performance of Li-S Batteries
Authors: Pandey Gaind P. , Adams Jada Imari , Callaway Jumia , Meda Lamartine 
Published: February 2020

Lithium-sulfur (Li-S) batteries have attracted considerable attention as one of the most promising next-generation energy storage system owing to the high theoretical specific capacity (1675 mAh g-1), low cost, natural abundance and environmentally benign nature of sulfur. However, the poor electrical conductivity of elemental S results in low utilization of S specific capacity, and hence, insufficient specific energy of Li-S batteries. Development of Li-S batteries is hindered by sluggish kinetics resulting from the intrinsic poor conductivity of sulfur and capacity degradation due to solubility of polysulfides intermediate. One strategy to overcome with these issues is to use of titanium disulfide (TiS2) as an additive to sulfur electrodes as it is a good electrical conductor and electrochemically active and also has the ability to adsorb polysulfide.
Herein, we investigated TiS2 as additive with sulfur using hierarchical architectures of carbon as effective hosts for S/TiS2. By a facile one-step melting diffusion method, we synthesized S/TiS2@carbon nanofibers (CNFs) composites in which TiS2 was uniformly distributed over the S-CNFs. The hierarchical S/TiS2@CNFs (TiS2, 20 wt%) electrodes shows good initial discharge capacity of 1085 mAh g−1 at 0.05 C rate with high mass loading of material (~6-6.5 mg/cm2 of composite) and ~99% initial coulombic efficiency. The composite electrode shows stable cycling performance for more than 100 charge-discharge cycles with specific capacity of ~750 mAh g-1 at a rate of C/3 and coulombic efficiency over 99%. Thus, in the presence of TiS2 additive, long cycle life and improved sulfur utilization of Li-S cells under high current rate (C/3) are demonstrated with high sulfur mass-loading.
Bipolar All-Solid-State Battery Enabled By a Perovskite-Based Hybrid Solid Electrolyte
Authors: Shin Hyun-Seop , Park Min-Sik , Jung Kyu-Nam , Lee Jong-Won 
Published: February 2020

The increasing number of fire/explosion incidents related to lithium-ion batteries (LIBs) for mobile devices and electric vehicles (EVs) in the recent years have raised significant concerns regarding their safety and reliability. The use of solid electrolytes provides a technical solution to address the safety issues of lithium-ion batteries and enables a bipolar design of high-voltage and high-energy battery modules. The bipolar design avoids unnecessary components and parts for packaging and electrical connection; therefore, it facilitates an increase in the volumetric energy density of the battery, while enabling easy build-up of total output voltage.
Here, we report the design and construction of a multi-layered bipolar ASSB using a hybrid solid electrolyte (HSE) membrane. The HSE membrane proposed in this work consists of inorganic Li0.29La0.57TiO3 (LLTO) perovskite and poly(ethylene oxide) (PEO). The perovskite-structured LLTO was selected as an inorganic solid electrolyte specifically as a result of its high Li+ conductivity, excellent mechanical strength, and high chemical stability against moisture. The hybridization of LLTO with PEO allows for the fabrication of thin and large-area electrolyte membranes with high ionic conductivity, without the need for high-temperature sintering. Moreover, the soft and adhesive PEO improves the interfacial contact between the electrolyte and electrode, resulting therefore in enhanced electrochemical performance of the prepared ASSBs. Although the concept of hybridization between inorganic material (garnet-Li7La3Zr2O12 and NASICON-Li1.5Al0.5Ge1.5(PO4)3) and polymer has been proposed previously, the focus in these earlier studies has been predominantly on optimizing the electrolytes to improve their Li+-conducting and/or mechanical properties and/or demonstrating their applications in the monopolar-type, small-sized ASSB. By contrast, little attention has been given to the design and fabrication of bipolar ASSBs with HSEs, which is essential for demonstrating the feasibility of HSEs in large-scale ASSBs with high voltage and energy. In this study, the HSE membranes based on LLTO and PEO were synthesized in the form of flexible and freestanding sheets with a thickness of ~30 mm using a simple casting method. The optimized HSE membrane exhibits remarkably enhanced Li+ conductivity, electrochemical window, and thermal stability when compared to a solid PEO-only membrane, facilitating reversible charge–discharge operations of ASSBs. Finally, a proof-of-concept bipolar ASSB comprising three unit cells connected in series was designed and constructed using the HSE membrane, and its electrochemical performance was investigated.
High Energy Density Li-Air Battery with the Polymer Electrolyte Coated CNTs Electrode Via Layer-By-Layer Method
Authors: Lee Hyunpyo , Lee Dong Joon , Kim Mokwon , Kim Hyunjin , Kwon Hyuk Jae , Lee Heung Chan , Im Dongmin 
Published: February 2020

The Li-air battery has attracted attention for several decades due to its high theoretical energy density (> 3400 Wh/kg). However, it has not been clearly demonstrated that the actual volumetric and gravimetric energy densities are higher than those of Li-ion batteries. In previous studies, generally quite a large amount of electrolyte was employed in preparing the Li-air cells. Usually the electrolyte was much heavier than the carbon materials in the cathode, which made the practical energy density of Li-air battery lower than that of Li-ion batteries. Therefore, the air cathodes with significantly lower amount of electrolyte need to be developed to achieve high specific energy density in Li-air batteries.
In this study, we propose a core-shell structured cathode material with a gel-polymer electrolyte layer covering the carbon nanotubes (CNT). The CNTs were synthesized via a floating catalyst chemical vapor deposition (FCCVD) method. The polymeric layer corresponding to the shell was prepared by a Layer-by-Layer (LbL) coating method utilizing Li-Nafion and PDDA-Cl (poly(diallyldimethylammonium chloride)) together. Several bi-layers of Li-Nafion and PDDA on the CNTs surface were successfully prepared and characterized with XPS, FT-IR, and TGA. The porous structure of the CNTs was found to remain after LbL process, which was confirmed by a nitrogen adsorption/desorption profile and BJH pore size distribution analysis. The porous structure could act as the oxygen channels facilitating the transport of oxygen molecules to react with Li ions on cathode surface. These polymeric bi-layers could provide Li ion pathway after absorbing a small amount of ionic liquid electrolyte, 0.5M LiTFSI EMI-TFSI (1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide). Compared with typical cathode where only liquid electrolytes were employed, the total amount of electrolyte in the cathode could be significantly reduced, thus the overall cell energy density could be increased. A Li-air battery with this core-shell structured cathode exhibited a high energy density, ~390 Wh/kg, which was assessed by directly weighing all cell components together including GDL (gas diffusion layer), an interlayer (a separator containing a mixture of LiTFSI, 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (PYR-14) and PDDA-TFSI), lithium anode and LbL-CNTs cathode. The cycle life of an LbL-CNTs based cathode was found to be 31 cycles, which was not an excellent performance, but nearly twice better than that of CNTs cathode without polymer coats.

Figure 1
High-Throughput Electrochemical Conversion of Gaseous CO2 to C≥2 Products By Fine-Tuning Structure of La2-XSrxCuO4±δ electrocatalyst
Authors: Kolla Praveen , Sun Qiang , Wang Wang , Mukerjee Sanjeev 
Published: February 2020

Among other metal catalysts, Copper (Cu) is a well-known for electrochemical reduction of CO2 and its selectivity primarily governed by the applied electrode potential and yields a wide-range of gaseous and liquid products. Specifically, CO2 electroreduction to formic acid, carbon monoxide (CO) and methane were observed at low-potentials <-1.0 V RHE (1), whereas ethylene, ethanol and n-propanol were yielded at high-potentials >-1.0 V RHE (2). On the other hand, catalytic activity of Cu inherently contributes from mixed oxidation states, surface roughness and aspect ratio of nanostructures. Consequently, different strategies such as oxide-derived, mixed metal-oxides, electrooxidized or anodized Cu-surfaces have been investigated to tune its catalytic activity. In addition, Cu-surfaces of different morphologies - spikes, steps and edges, or its nanostructures having different shapes and dimensionality were thoroughly investigated. However, electrochemical performance of Cu-electrocatalysts eventually declines as surface morphology fades out and/or while Cun+ quickly retains its pure metallic-state during long-term electrolysis under electrochemical reduction potentials (3). Moreover, due to limited CO2 solubility in aqueous electrolytes and inability of Cu for direct-activation of gaseous-reactant (CO2(g)), these catalysts displayed low-throughputs (<30 mA/cm2).
In this context, our research demonstrates how Cu-based perovskite-oxides of A2BO4-type, with Cu on B-site, are crucial for electrochemical CO2 reduction and its product selectivity. This presentation sheds light on how these catalysts are unique for fine-tuning Cu-oxidation state with control of lanthanum-elements (on A-site) and/or its partial doping with element of slightly different oxidation-number. This work specifically provides synthetic means of optimizing Cu-structure by relative-doping (x) in La2-xSrxCuO4±δ along with identification/preservation of responsible active-site and depicts the underlaying mechanistic aspects of CO2-electroreduction towards ethanol, n-propanol, and ethylene. The presentation also highlights how the overall oxygen deficient-sites (δ) created within the structure of A2BO4±δ are not only critical for direct activation of gaseous CO2, but also promote throughputs (up to 100-200 mA/cm2) required for commercial implementation.

References:

M. Gattrell, N. Gupta and A. Co, Journal of Electroanalytical Chemistry, 594, 1 (2006).

D. Ren, Y. Deng, A. D. Handoko, C. S. Chen, S. Malkhandi and B. S. Yeo, ACS Catalysis, 5, 2814 (2015).

C. W. Li and M. W. Kanan, Journal of the American Chemical Society, 134, 7231 (2012).
Novel Synthesis of Mn-Ni-Co Oxide(MNCO)@g-C3N4 Ternary Ribbon-like Hetero Nanocomposite for Psuedocapacitor Applications
Authors: Mawari Nemi Chand , Meher Sumanta Kumar 
Published: February 2020

Since last few years, the hassle of clean, efficient, and renewable energy sources is remarkable and thereby driving intense scientific concern in the production, storage and management of this precious energy. Among variety of electrical energy storage devices, supercapacitors (SCs), also known as electrochemical capacitors, have industrial attention because of their high power density and very long cyclic stability as compared to their counterparts such as batteries, fuel cells and conventional capacitors etc.
To improve the electrochemical properties of the electrode materials, Mn-Ni-Co-Oxide(MNCO)@g-C3N4 Ribbon-like Hetero-nanoarrays were synthesized by a simple two-step approach including hydrothermal method and subsequent calcination process. This ternary metal oxide composite was directly utilized for the psuedocapacitive investigation because it is believed that these three metal elements can provide synergistic effects during the redox reaction process compared to the single component metal oxides. Due to similar atom radii of the elements, Mn-Ni-Co ternary oxide (MNCO)@g-C3N4 without crystal structure change has been identified as one kind of the most attractive supercapacitive electrode materials.
The chemical composition and morphology of the material was characterized by XRD, EDS and FESEM and HRTEM techniques. The electrochemical capacitance of MNCO@g-C3N4 was examined by cyclic voltammetry, galvanostatic charge–discharge and electrochemical impedance measurements. Results shows that the MNCO@g-C3N4 electrode material exhibits electrochemical activity for supercapacitor applications. A maximum specific capacitance value of 5624 F g-1 could be obtained under an applied current density of 1 Ag-1 in 6 mol L-1 KOH electrolyte. It is envisaged that the novel MNCO@g-C3N4 ternary oxide composite material can be an alternate electrode material for high-performance supercapacitor application.
Hot Holes Assist Plasmonic Nanoelectrode Dissolution
Authors: Al-Zubeidi Alexander , Hoener Benjamin S , Collins Sean Stevenson Edward , Wang Wenxiao , Kirchner Silke , Hosseini Jebeli Seyyed Ali , Joplin Anneli , Chang Wei-Shun , Link Stephan , Landes Christy F 
Published: February 2020

Strong light absorbing properties, and the ability to drive electrochemical reactions on their surface has sparked, allow plasmonic metal nanoparticles to serve as photocatalysts. After plasmon excitation, hot charge carriers are generated in the metal nanoelectrode, driving electrochemical reactions. To achieve plasmonic photocatalysis, the hot charge carriers must be harnessed before they decay by giving off heat to the surroundings. Here, we demonstrate the role of photogenerated hot holes in oxidative electrodissolution of individual gold nanorods in chloride electrolyte. We monitor the plasmon resonance spectroscopically using snapshot hyperspectral imaging with millisecond time resolution, while electrochemically tuning charge carrier density. We show that light induced hot charge carriers enhance the rate of gold oxidation and subsequent electrodissolution tenfold. Importantly, we find that hot holes generated from interband transitions compared to holes in the sp-band around the Fermi level contribute to electro-oxidation. We further show that the reaction onset potential cannot be lowered below the chloride onset potential, demonstrating that electrochemical mediation is required. These results provide new insights into hot hole driven photocatalysis while emphasizing the need for statistical descriptions of electrochemical non-equilibrium processes on innately heterogeneous nanoparticle supports.
Figure: Schematic representation of experimental setup and mechanism. a: when positive potentials are applied while illuminating the nanoparticle, the scattering intensity and hence volume of the nanoparticle decreases (see inset). b: photo-generated hot holes inject into the HOMO of adsorbed chloride.

Figure 1
Study of the Electrochemical Mechanism of Dyes in Ionic Liquid By NIR Spectroelectrochemistry
Authors: Fanjul Pablo , Ibáñez David , Junquera-Pérez Alejandro , González-García María Begoña , Hernández-Santos David 
Published: February 2020

Over the last years, near infrared (NIR) spectroscopy has received growing attention because it is a fast, non-destructive and non-invasive technique. In order to provide vibrational information of different systems, NIR spectroscopy is an interesting alternative rather than other techniques. However, it is well-known the aqueous limitation in NIR spectroscopy due to the high absorbance of water in this spectral range.
In this work, a new methodology based on ionic liquids is proposed to overcome the water restriction. Ionic liquids are an interesting alternative because they show excellent properties such as wide electrochemical potential window, good ionic conductivity and high thermal stability, and also, they do not display aqueous contribution.
As result of the combination of NIR spectroscopy and electrochemistry in a novel instrument, the simultaneous acquisition of information of different nature in a unique experiment allows monitoring different processes that take place on the electrode surface. As proof of concept, the electrochemical behavior of two dyes (crystal violet and malachite green) with similar chemical structure have been studied by NIR spectroelectrochemistry. They show different electrochemical response as well as different NIR spectra: crystal violet requires more positive potentials to be oxidized and its NIR spectrum displays 2 bands at 1000 and 1200 nm, while malachite green is oxidized at lower potential and only shows one NIR band at 1255 nm. Combination of electrochemistry and NIR spectroscopy allows to understand the electrochemical mechanism of both dyes. In this way, NIR spectroelectrochemistry opens new gates not only for qualitative purposes but also for quantitative applications as for example for the resolution of mixtures.
Mechanistic Insights into Enzymatic Nitric Oxide Reduction Revealed By Surface-Enhanced Infrared Absorption Spectroscopy
Authors: Kato Masaru , Masuda Yuya , Nakagawa Shogo , Tosha Takehiko , Yagi Ichizo 
Published: February 2020

Biological nitric oxide reduction occurs in certain bacteria containing nitric oxide reductases (NORs). The NOR is a transmembrane metalloenzyme and selectively catalyzes the reduction of nitric oxide (NO) to nitrous oxide (N2O) in the microbial denitrification process. The enzymatic NO reduction is catalyzed at a binuclear active center of the non-heme FeB and the heme b
3.[1] The molecular mechanism of the enzymatic NO reduction has been extensively studied using physicochemical techniques including protein film electrochemistry.[2] However, the molecular mechanism still remains under debate.
Herein, we report electrochemical and spectroscopic studies on protein film electrochemistry and surface-enhanced infrared absorption (SEIRA) spectroscopy of NOR-modified gold electrodes. The NOR was isolated from P. aeruginosa and then immobilized on SEIRA-active gold electrodes via a self-assembled monolayer of alkyl thiols. The NOR-modified gold electrode showed electrocatalytic NO reduction currents with an onset potential of ca. –0.4 V vs. SHE. Potential-dependent SEIRA spectra of the NOR-modified electrode under CO, which was used as a vibrational probe to identify the electrochemical reduction of iron cofactors, showed a characteristic band at 1972 cm–2 at –0.4 V vs. SHE. This band was associated with the CO binding to heme b
3. Thus, these results suggest that the heme b
3 should be involved in the enzymatic NO reduction.[3] SEIRA spectra of the NOR-modified electrode in the presence of NO are underway to understand the binding mode of NO to iron cofactors in the electrocatalytic condition.

References

[1] T. Hino, Y. Matsumoto, S. Nagano, H. Sugimoto, Y. Fukumori, T. Murata, S. Iwata, Y. Shiro, Science, 330, 1666–1670 (2010).
[2] C. M. Cordas, A. G. Duarte, J. J. G. Moura, I. Moura, Biochim. Biophys. Acta, 1827, 233–238 (2013).
[3] M. Kato, S. Nakagawa, T. Tosha, Y. Shiro, Y. Masuda, K. Nakata, I. Yagi, J. Phys. Chem. Lett., 9, 5196–5200 (2018).
Stress-Induced Interface Instability during Ion Intercalation in Battery Compounds
Authors: Zhang Youtian , Tang Ming 
Published: February 2020

Misfit stress generated by lattice mismatch between the lithiated and delithiated phases upon ion (de)intercalation plays a key role in cycling-induced mechanical degradation and capacity fading of battery electrodes. As a general phenomenon, misfit stress also leads to interface instability. A well-known example is the stress-induced island growth or the Stranski-Krastanov growth mode of epitaxial thin films, where the misfit strain between thin film and substrate destabilizes the uniform film growth. In this work, we predict that similar phenomenon can also occur during the ion (de)intercalation process in battery compounds, in which the misfit stress triggers the morphological instability of the moving phase boundary. This phenomenon results in non-uniform (de)intercalation, leading to capacity under-utilization and battery degradation and even failure due to stress concentration, and therefore needs to be carefully mitigated to improve battery performance.
In our theoretical analysis, we consider the kinetic evolution of a sinusoidal perturbation applied to an initially flat interface between the lithium-rich and lithium-poor phases upon (de)lithiation under constant overpotential or flux conditions. The perturbation growth rate is calculated from the linear stability analysis. For interface-limited phase boundary movement, there exists a critical wavelength above which perturbation will growth. On the other hand, two critical wavelengths are identified for diffusion-limited phase transformation, and only perturbations with wavelengths between them will grow with time. The growth exponents predicted by the linear stability theory agree well with phase-field simulations. Based on the analysis, a stability diagram for lithium (de)intercalation is constructed in the space of particle size, applied overpotential (or intercalation flux) and interface location, as shown in Figure 1. Such diagram provides guidance on the conditions at which stress-induced Li intercalation instability can be avoided.
A useful insight from our study is that the interface is most susceptible to instability when it is near the electrode particle surface, i.e. at the beginning of (dis)charge process. Accordingly, we propose a (dis)charging strategy to suppress the instability, in which a high Li flux pulse is applied at the initial (de)lithiation stage to stabilize the interface until it moves into the particles. We compare interface evolution in this (dis)charging protocol against during galvanostatic cycling in phase-field simulations. It shows that the proposed strategy can effectively prevent interface instability, which results in an increase in the (dis)charge capacity and reduction in localized stress hotspots.

Figure 1
Electrostatics to Electrodynamics Via an Additional Frame of Reference
Authors: Kennell Glyn , Evitts Richard 
Published: February 2020

There are many different methods for modeling the electric field coupled with electrolytic transport. Many mechanistic methods are based on Maxwell's equations and Gauss' law of electrostatics with added simplifications and/or assumptions. One common simplification is that the accumulation of charge density may be neglected and electroneutrality may be assumed. Another method might allow for the accumulation of charge density which may then be used as in independent variable in Poisson's equation to calculate the electric field, where Poisson's equation is developed from Gauss' law of electrostatics. One such common example is the Nernst-Planck-Poisson equation set.
This research presents a method to go from electrostatics to electrodynamics using an additional frame of reference and also invoking Newton's third law, allowing the incorporation of Ohm's law into Maxwell's equations. This approach allows for the derivation of electrodynamics that may be used to model the electric field coupled with electrolytic transport. In addition, this research presents a model and results where an electrolyte transport equation is coupled with an electrodynamic equation for the electric field. This model is used to simulate a variety of phenomena including liquid-junctions and electric current distributions. Results are compared with experimental and numerical results of others. The overall model is also tested for multi-dimensional multi-component transport and electric current distributions. This model is also applied to the more complex situation of a multi-scale lithium-ion battery with different sized electrodes undergoing charging.