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On the crystallography and reversibility of lithium electrodeposits at ultrahigh capacity
Abstract Lithium metal is a promising anode for energy-dense batteries but is hindered by poor reversibility caused by continuous chemical and electrochemical degradation. Here we find that by increasing the Li plating capacity to high values ( e.g ., 10–50 mAh cm −2 ), Li deposits undergo a morphological transition to produce dense structures, composed of large grains with dominantly (110) Li crystallographic facets. The resultant Li metal electrodes manifest fast kinetics for lithium stripping/plating processes with higher exchange current density, but simultaneously exhibit elevated electrochemical stability towards the electrolyte. Detailed analysis of these findings reveal that parasitic electrochemical reactions are the major reason for poor Li reversibility, and that the degradation rate from parasitic electroreduction of electrolyte components is about an order of magnitude faster than from chemical reactions. The high-capacity Li electrodes provide a straightforward strategy for interrogating the solid electrolyte interphase (SEI) on Li —with unprecedented, high signal to noise. We find that an inorganic rich SEI is formed and is primarily concentrated around the edges of lithium particles. Our findings provide straightforward, but powerful approaches for enhancing the reversibility of Li and for fundamental studies of the interphases formed in liquid and solid-state electrolytes using readily accessible analytical tools.
Creating electrochemical accessibility in covalent organic frameworks for uranium extraction via electrodeposition
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Anodization control for barrier-oxide thinning and 3D interconnected pores and direct electrodeposition of nanowire networks on native aluminium substrates
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Co-electrodeposition of RuO2-MnO2 Nanowires and the Contribution of RuO2 to Capacitance Increase
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Investigation of the water-stimulated Mg 2+ insertion mechanism in an electrodeposited MnO 2 cathode using X-ray photoelectron spectroscopy
In water-containing organic electrolyte, the charge storage of amorphous MnO 2 combines Mg(OH) 2 formation at the cathode surface and Mg insertion.
Electrodeposition of nanometer-thick epitaxial films of silver onto single-crystal silicon wafers
Silver films were deposited epitaxially for the first time onto low-index, single-crystal silicon wafers through an electrochemical method in an aqueous silver acetate bath. A negative potential of -2.34 V vs. Hg/Hg 2 SO 4 was used for both pre-polarization and during the deposition to avoid Si oxidation. The epitaxy of Ag films on Si(111), (110) and (100) was characterized by X-ray diffraction symmetric scans and pole figures. The Ag films showed [111], [110] and [100] out-of-plane orientations, respectively, with in-plane order determined by the Si substrates. Interface models consistent with the observed orientations invoke coincident site lattices (CSLs), in which four unit meshes of Ag coincide with three unit meshes of Si. These CSLs reduce the lattice mismatch from -24.9% to +0.13%. A thickness of about 10 nm was obtained for Ag deposited for ten minutes. A comparison of silver acetate electrolyte and cyanide electrolyte was also performed, showing advantages of the acetate bath over the cyanide bath for growth of epitaxial films of Ag on Si surfaces.
Electrodeposited Sn–Cu@Sn dendrites for selective electrochemical CO 2 reduction to formic acid
Large-scale CO 2 electrolysis can be applied to store renewable energy in chemicals. Recent developments in gas diffusion electrodes now enable a commercially relevant current density. However, the low selectivity of the CO 2 reduction reaction (CO 2 RR) still hinders practical applications. The selectivity of the CO 2 RR highly depends on the electrocatalyst. Sn catalysts are considered promising cathode materials for the production of formic acid. The selectivity of Sn catalysts can be regulated by controlling their morphology or alloying them with secondary metals. In this work, we enhanced the selectivity of CO 2 reduction to formic acid by synthesizing Sn–Cu@Sn dendrites that have a core@shell architecture. The Sn–Cu@Sn dendrites were prepared by a scalable electro-deposition method. The electronic structure was modified to suppress a reaction pathway for CO production on the Sn surface. Notably, the Sn shell inhibited the cathodic corrosion of Cu during the CO 2 RR. On a gas diffusion electrode, the Sn–Cu@Sn dendrites exhibited 84.2% faraday efficiency to formic acid for 120 h with high stability.
Understanding ion-transfer reactions in silver electrodissolution and electrodeposition from first-principles calculations and experiments
Density functional theory simulations and potential-step experiments reveal the atomic charge interactions that govern the ion-transfer kinetics at the electrified solution/Ag interface, providing new insights for energy technology applications.
High electrical conductivity in out of plane direction of electrodeposited Bi 2 Te 3 films
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Electrodeposition of MoS x : Tunable Fabrication of Sulfur Equivalent Electrodes for High Capacity or High Power
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Erratum: An Analysis of Solid-State Electrodeposition-Induced Metal Plastic Flow and Predictions of Stress States in Solid Ionic Conductor Defects [J. Electrochem. Soc., 167, 020534 (2020)]
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Rationalizing Calcium Electrodeposition Behavior by Quantifying Ethereal Solvation Effects on Ca 2+ Coordination in Well-Dissociated Electrolytes
Ca-ion electrochemical systems have been pushed to the forefront of recent multivalent energy storage advances due to their use of earth-abundant redox materials and their high theoretical specific densities in relation to monovalent or even other more widely explored multivalent-charge carriers. However, significant pitfalls in metal plating and stripping arise from electrolyte decomposition and can be related to the coordination environment around Ca 2+ with both the negatively charged anion and the organic–aprotic solvent. Here, we apply multiple spectroscopic techniques in conjunction with density functional theory to evaluate the coordination environment of Ca 2+ across a class of ethereal solvents. Through the combination of X-ray absorption fine structure and time-dependent density functional theory, descriptive measures of the local geometry, coordination, and electronic structure of Ca–ethereal complexes provide distinct structural trends depending on the extent of the Ca 2+ –solvent interaction. Finally, we correlate these findings with electrochemical measurements of calcium tetrakis(hexafluoroisopropoxy)borate (CaBHFIP 2 ) salts dissolved within this class of solvents to provide insight into the preferred structural configuration of Ca 2+ electrolytic solutions for optimized electrochemical plating and stripping.
Choline Chloride-Based Water-in-Salt Electrolyte for Efficient Iron Electrodeposition
Electrochemical production of iron is a promising low-cost and modular approach to replace the traditional blast furnace. Aqueous electrolytes for iron electrolysis are advantageous as they can be operated at near-ambient temperatures, but they suffer from inefficiencies due to the parasitic hydrogen evolution reaction. In this work, we identify a new water-in-salt electrolyte (WiSE) based on choline chloride (ChCl) for high coulombic efficiency (>85%) iron deposition. Electrochemical analysis of the partial current densities of iron plating and hydrogen co-evolution revealed that, at optimal WiSE compositions, water reduction is kinetically suppressed resulting in an increase in the Fe plating efficiency. Decreased coordination of water and increased coordination of choline’s alcohol group with the Fe 2+ ion were observed through 1 H NMR providing evidence that water reduction is kinetically suppressed in WiSE. Additionally, Raman spectroscopy revealed that complexation effects (with Cl – ) reduce Fe 2+ diffusion coefficients and corresponding limiting currents as the ChCl concentration is increased. This results in an optimal WiSE composition (4 M ChCl + 1 M FeCl 2 ) that provides kinetic suppression of HER but also low transport resistance to Fe plating yielding 85% coulombic efficiency at high current densities.