Recent advances in metallic glass nanostructures (MGNs) are reported, covering a wide array of synthesis strategies, computational discovery, and design solutions that provide insight into distinct ...electrocatalytic applications. A brief introduction to the development and unique features of MGNs with an overview of top‐down and bottom‐up synthesis strategies is presented. Specifically, the morphology and structural analysis of several examples applying MGNs as electrodes are highlighted. Subsequently, a comprehensive discussion of commonly employed kinetic parameters and their connection with the unique material structures of MGNs on individual electrocatalytic reactions is made, including the hydrogen evolution reaction, oxygen reduction reaction, and alcohol (methanol or ethanol) oxidation reaction. Finally, a summary of the challenges and perspective on the future research and development relevant to MGNs as electrocatalysts is provided.
The most recent advances of metallic glass nanostructures are discussed, including a wide array of synthesis strategies, computational discovery, and design solutions that provide insight into distinct electrocatalytic applications, along with a summary of the challenges and perspectives on the future research and development relevant to electrocatalysis.
Li–O2 battery technology offers large theoretical energy density, considered a promising alternative energy storage technology for a variety of applications. One of the main advances made in recent ...years is the use of soluble catalysts, known as redox mediators (RM), decreasing the charge overpotential and improving cyclability. Despite its potential, much is still unknown regarding its dynamic, especially over higher loading electrodes, where mass transport may be an issue and the interplay with common impurities in the electrolyte, like residual water. Here we perform for the first time an operando XRD characterization of a DMSO-based LiBr mediated Li–O2 battery with a high loading electrode based on CNTs aiming to reveal these dynamics and track chemical changes in the electrode. Our results show that, depending on the electrode architecture, the system’s issue can move from catalytic to a mass transfer. We also assess the effect of residual water in the system to better understand the reaction routes. As a result, we observed that with DMSO, the system is even more sensitive to water contamination compared to glyme-based studies reported in the literature. Despite the activity of LiBr on the Li-peroxide oxidation and its contribution to cyclability, with the system and electrode configuration used in this study, we verified that a mass transfer limitation caused a cell “sudden death” caused by clogging after cycling.
•O2 flow modify the chemical of the discharge products.•The absence of O2 flow increases the discharge capacity of Li-O2 cells.•Favored decomposition of LiOOH.H2O in comparison with LiOH in ...charge.•Formation of different discharge products change the electrode's morphology.
Many studies on Li-O2 batteries have addressed the chemical and morphological evolution of the device as a function of electrode material, electrolyte, and discharge current density. Here we report that simple operating conditions can also affect discharge product formation. Results show the formation of Li2O2 and LiOH in experiments using continuous O2 flow (open system) and without it (closed system), and an additional more complex chemistry including LiOOH•H2O, Li2O and LiO2 in the closed system. This unexpected difference was also examined during charging of the Li-O2 cell, in which the LiOOH•H2O is preferably reversed in comparison to LiOH. Beside the influence in the reaction routes, the O2 flow and pressure impact on the cell performance. The total discharge capacity varies from 1,459 mA g − 1 to 2,460 mA g − 1 decreasing the O2 flow. In contrast, when using the closed pressurized system, the discharge capacity increased up to 5,851 mA g − 1 with the same electrode in the best result, as the electrolyte loss due to evaporation was avoided.
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•Combined model of a hydrophobic membrane in an air-breathable Li-air battery.•Model correlates water concentration and shape factor of discharge product.•Moisture influx in batteries should be ...controlled to avoid performance losses.•Benchmark membrane permeability tested in the model.•Water permeability below 1.6 mg m−2 d−1 to allow operation with ambient air.
Lithium-air batteries are presented in the literature as a candidate for electrochemical energy storage because of their potentially high energy density. Part of this high energy density comes from the fact that one of its components – oxygen – can be sourced from the air. However, when operating with ambient air, these batteries are exposed to contamination with water, a component that may damage the Li electrode. Bearing this in mind, this work analyzes the potential of hydrophobic membranes in allowing lithium-air batteries to work with ambient air containing moisture. For this investigation, a model that includes the influence of water concentration in the electrolyte (LiClO4 in dimethyl sulfoxide) on the morphology of the discharge product was developed based on experimental data. Results demonstrate that membrane permeability should be lower than currently available technologies to satisfactorily reduce the increase in water concentration over time. According to simulation results, membrane permeability for water should be below 0.2 mg m−2 d−1 for a current density of 0.25 A m−2 or 1.6 mg m−2 d−1 for a current density of 0.75 A m−2 to allow a water concentration increase of only 1 ppm after each discharge. This severe limitation in membrane permeability requirement indicates that a moisture-controlled O2 source for Li-air or Li-O2 batteries in a closed system might be preferred to preserve electrolyte properties.
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•A novel model for studying redox-active materials used in supercapacitors.•Capacitance and pseudocapacitance are indistinguishable phenomena.•Accurate simulations using different electrochemical ...techniques.•Experimental capacitance and resistance values are technique-dependent.
This work presents a new methodology to interpret the electrochemical behavior of pseudocapacitors (PCs) which is based on a new theoretical approach denoted as the generic electrochemical model (GE). Based on a single premise, the GE model is composed of two distinct time constants (τ = RC) used to represent the narrow-deep (n-d) and large-shallow (l-s) heterogeneous surface structures incorporating the different surface defects (e.g., cracks, fissures, pores, etc.), which incurs in the so-called distributed capacitance and resistance phenomena. Five different transition metal oxide (TMO) electrodes composed of Ni, Co, and Ru were used to verify the validity of the proposed model equations. The internal (inner) and external (outer) capacitances and resistances were accurately determined from the fitting analysis (e.g., r2 ≥ 0.998 and χ2 < 10–5) involving the findings obtained using different techniques. Therefore, disagreements between the electrochemical techniques regarding the resistance and capacitance absolute values were ascribed to different average penetration depths intrinsic to each particular perturbation function, i.e., each electrochemical technique exhibits a particular sensitivity for detecting the capacitive and resistive phenomena in porous/defective electrodes. We verified for well-behaved PCs, where the so-called battery-like behavior is absent, that capacitive and pseudocapacitive phenomena are indistinguishable phenomena, as predicted by Saveànt and Conway. Therefore, the GE model can also be used for studying different carbon-based materials used in supercapacitors. Finally, the presence of different surface heterogeneous structures present in defective electrodes is the main cause of the distributed capacitance and resistance verified in both time and frequency domains.
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This review presents recent in situ FTIR spectroscopy contributions to lithium-ion batteries and other battery systems. It details the advantages of using in situ FTIR spectroscopy technique to study ...different battery systems and spectro-electrochemical cells. This technique can hopefully become a protocol for supporting the design of novel materials for batteries.
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In situ and operando infrared spectroscopies are powerful techniques to support the design of novel materials for batteries and the development of new battery systems. These techniques can support the study of batteries by identifying the formation of new species and monitoring electrochemical energy stability. However, few works have employed these techniques, which can be used to investigate various materials, including systems beyond lithium-ion technology, in the research of batteries. Therefore, this review presents a comprehensive overview focusing on the main contributions of in situ and operando infrared spectroscopy for lithium-ion batteries (LIBs) and other battery systems. These techniques can successfully identify the formation of species during the electrolyte reduction, electrode degradation, and the formation of the solid-electrolyte interphase (SEI) layer. From these outcomes, it is possible to conclude that this characterization approach should be employed as a protocol to overcome remaining issues in batteries, consequently supporting battery research. This review aims to be a guide on how infrared spectroscopy can contribute to monitoring battery systems and to lead researchers interested in applying this technique.
The fast decomposition of peroxides (M2O2, where M = H+, Li+) at room temperature has gained increased attention given its relevance, from propulsive systems to metal-O2 conversion batteries. This ...study describes, by a rational design of experiment, the influence of selected parameters such as: pH, initial concentration of K2CO3, precipitate aging, precipitate washing, and thermal treatment for the hydrotalcite co-precipitation, characterizing it for each synthesis variable. The results show that hydrotalcites can efficiently be converted in Co-Mn-Al spinels and as a result, a new highly active Co2Mn0.5Al0.5O4 spinel oxide was synthesized after thermal treatment. Its activity and mechanical resistance were tested in a micro-thruster reactor where it showed total decomposition (> 98%) of H2O2 and in a Li-O2 battery, with increased cyclability, been able to reduce the charging potential in ~200 mV. These encouraging results enhance the importance not only of this class of material, but also, the importance of robust synthesis methodologies for reproducible results.
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•Hydrotalcites can be converted in a single-phase spinel catalyst.•Synthesis conditions influence in the catalyst’s activity and mechanical resistance.•Co2Mn0.5Al0.5O4 spinel can efficiently decompose concentrated H2O2.•Co2Mn0.5Al0.5O4 spinel act as bifunctional catalyst in lithium-air batteries.
This paper provides guidelines on the fabrication and operation of alkaline fuel cells using quaternary ammonium hydroxide anion exchange membrane (FAA-3 – fumatech), and includes a discussion of the ...electrode kinetic parameters based on the composition of the catalytic layer. The best peak power density performance, 223 mW cm−2 was obtained with an electrode formed from Pt/C, 0.8 mgPt cm−2 and 25% of FAA-3 ionomer in the catalyst layer for both the cathode and the anode. We demonstrate that the platinum loading can be lowered to values close to 0.5 mgPt cm−2, without appreciably affecting the fuel cell performance characteristics. The experimental fuel cell data were analyzed using theoretical models of the electrode structure and its kinetics studied over the assembling parameters. We show that most of the electrode systems present limiting currents, with some showing diffusion limitations in the gas channels and/or in the ionomer film covering the catalyst nanoparticles. We also provide some general strategies using Tafel slopes on evaluating the ionomer interaction with the electrode kinetics for the oxygen reduction reaction.
► Guidelines on the fabrication and operation of HEM fuel cells. ► Discussion of electrode kinetic parameters and its assembly impacts. ► Provides criteria for optimized operation of commercially available GDL materials. ► Relationship between nature of ionomer and reaction resistance within the catalytic layer.
The Double-Edged Effect of Water on Li-O2 Aprotic Batteries Policano, Martim Chiquetto; Anchieta, Chayene Gonçalves; Carpanedo de Morais Nepel, Thayane ...
Journal of the Electrochemical Society,
04/2023, Letnik:
170, Številka:
4
Journal Article
PDF
