Electrolyte Of Na Research Articles

Transverse and Longitudinal Degradations in Ceramic Solid Electrolytes

Ceramic solid electrolytes conducting primarily a specific ion but with minuscule electron leakage are used in many electrochemical devices. Their degradation phenomena may be classified into two broad categories─a slow transverse mode accumulating damage normal to the ionic current direction and a fast longitudinal mode accumulating degradation parallel to the current direction. Examples of the transverse mode include oxygen bubbles on transverse grain boundaries, in-plane electrolyte cracking in solid oxide electrolysis cells, and cathodic reduction of beta-alumina electrolytes in Na–S batteries. Examples of the longitudinal mode include short-circuiting dendrite formation in metal batteries of both the Na–S type and the all-solid-state lithium metal type. Analogous instability modes are also seen in field-assisted ceramic processing, dielectric devices, and memristors. These phenomenological similarities across different devices, operating conditions, and technologies, as well as the origins of their damage mechanisms, can be understood in terms of the highly nonlinear spatial distributions of the minority carriers (electron/hole) and the chemical potential of the equivalent charge-neutral species such as O2; such distributions can in turn cause or exacerbate damaging concentrations of stress and electric fields. This review also outlines strategies for improving material designs to mitigate degradation, which will be especially important for operations and applications under extreme electrochemical conditions.

Excellent Electrolyte Wettability and High Energy Density of B2S as a Two-Dimensional Dirac Anode for Non-Lithium-Ion Batteries.

Two-dimensional (2D) Dirac materials with ultrahigh electronic conductivity exhibit great promise for application as an anode material in non-lithium-ion batteries (NLIBs) with a reduced conductive additive and a binder as a nonactive material additive. Graphene is one of the most prominent 2D Dirac materials with high electrolyte wettability; however, it cannot be used as an anode material in NLIBs owing to its poor affinity toward metal ions such as Na, K, Ca, Mg, and Al. In this work, we investigated the use of recently developed boron sulfide (B2S) as a new lightweight 2D Dirac anode for NLIBs on the basis of first-principles calculations. We demonstrate that B2S delivers excellent electronic conductivity and has a unique "self-doping" effect by forming S or B vacancies. The ultrahigh energy densities of 2245 and 1167 mWh/g, a product of capacity and open-circuit voltage referenced by standard hydrogen electrode potential ( Cao Nat. Nanotechnology . 2019 , 14 , 200 - 207 ), could be achieved for the B2S anode in Na- and K-ion batteries, respectively, significantly larger than those of graphene. More importantly, the B2S presents graphene-like wettability toward commonly used electrolytes in Na- and K-ion batteries, i.e., the solvent molecules and metal salt, indicating excellent compatibility. Moreover, the minimum energy path for Na- and K-ion diffusion on the B2S surface shows energy barriers of 0.19 and 0.04 eV, which indicates high ionic conductivity. Furthermore, a small contraction of the B2S lattice upon ion intercalation has been observed due to the adsorption-induced corrugation of the electrode, which offsets the lattice expansion. The results suggest that the B2S electrode can be used as a lightweight 2D Dirac anode material with excellent energy density, desirable rate performance, and robust wettability toward the electrolytes.

Role of Electrolyte Anions in the Na–O2 Battery: Implications for NaO2 Solvation and the Stability of the Sodium Solid Electrolyte Interphase in Glyme Ethers

Herein we investigate the influence of the sodium salt anion on the performance of Na–O2 batteries. To illustrate the solvent–solute interactions in various solvents, we use 23Na-NMR to probe the environment of Na+ in the presence of different anions (ClO4–, PF6–, OTf–, or TFSi–). Strong solvation of either the Na+ or the anion leads to solvent-separated ions where the anion has no measurable impact on the Na+ chemical shift. Contrarily, in weakly solvating solvents the increasing interaction of the anion (ClO4– < PF6– < OTf– < TFSi–) can indeed stabilize the Na+ due to formation of contact ion pairs. However, by employing these electrolytes in Na–O2 cells, we demonstrate that changing from weakly interacting anions (ClO4–) to TFSi does not result in elevated battery performance. Nevertheless, a strong dependence of the solid electrolyte interphase (SEI) stability on the choice of sodium salt was found. By correlation of the physical properties of the electrolyte with the chemical SEI composition, the cru...

High quality oxide-layers on Al-alloy by micro-arc oxidation using hybrid voltages

Abstract Oxide layer was grown on 6061 Al alloy by micro arc oxidation (MAO) using a power supply of hybrid voltages: direct (V DC ) and alternative (V AC ) ones. The power supply was set at a fixed V AC voltage maintained at a value between 240 and 320 V coupled with an in-series V DC which is auto-tuned to keep the constant current density 5 A dm − 2 . This led to varying ratios of final V DC versus maximum V AC (V DC-final /V AC-max ) as the major processing parameter. Alkaline solution containing electrolytes of Na 2 SiO 3 , NaH 2 PO 2 ·H 2 O, and Na 2 WO 4 ·2H 2 O was used. All MAO samples show an oxide layer thickness around 10 μm after 30 min operation time. For samples MAO with V AC-max 320 V SEM morphology indicates a smoother oxide-layer surface with uniform micro-pores, which have mean diameters less than 1 μm. XRD patterns show the main oxide-phases of hexagonal α-Al 2 O 3 , cubic γ-Al 2 O 3 and mullite (Al 2 O 3 · n SiO 2 ). Micro-hardness of MAO samples increases from 960 HV (V AC 240 V) to 1480 HV (V AC 320 V). Corrosion resistance of the MAO layer is significantly improved with reducing V DC-final /V AC-max . Samples by V AC-max 320 V show the minimum corrosion current density 6.28 × 10 − 9 A cm − 2 , corresponding to the highest polarization resistance 2.20 × 10 8 Ω cm 2 . Comparing with MAO layers obtained by using V DC only, the oxide-layer by hybrid voltages is a little thinner, much harder and much more corrosion resistant.

Use of Nonelectrolytes Reveals the Channel Size and Oligomeric Constitution of the Borrelia burgdorferi P66 Porin

In the Lyme disease spirochete Borrelia burgdorferi, the outer membrane protein P66 is capable of pore formation with an atypical high single-channel conductance of 11 nS in 1 M KCl, which suggested that it could have a larger diameter than ‘normal’ Gram-negative bacterial porins. We studied the diameter of the P66 channel by analyzing its single-channel conductance in black lipid bilayers in the presence of different nonelectrolytes with known hydrodynamic radii. We calculated the filling of the channel with these nonelectrolytes and the results suggested that nonelectrolytes (NEs) with hydrodynamic radii of 0.34 nm or smaller pass through the pore, whereas neutral molecules with greater radii only partially filled the channel or were not able to enter it at all. The diameter of the entrance of the P66 channel was determined to be ≤1.9 nm and the channel has a central constriction of about 0.8 nm. The size of the channel appeared to be symmetrical as judged from one-sidedness of addition of NEs. Furthermore, the P66-induced membrane conductance could be blocked by 80–90% by the addition of the nonelectrolytes PEG 400, PEG 600 and maltohexaose to the aqueous phase in the low millimolar range. The analysis of the power density spectra of ion current through P66 after blockage with these NEs revealed no chemical reaction responsible for channel block. Interestingly, the blockage of the single-channel conductance of P66 by these NEs occurred in about eight subconductance states, indicating that the P66 channel could be an oligomer of about eight individual channels. The organization of P66 as a possible octamer was confirmed by Blue Native PAGE and immunoblot analysis, which both demonstrated that P66 forms a complex with a mass of approximately 460 kDa. Two dimension SDS PAGE revealed that P66 is the only polypeptide in the complex.

Congo Red Degradation in Anode and Sunlight/derivative Persulfate Composite Oxidation System

AbstractAnodic oxidation and sulphate radical oxidation were combined in the study for degradation of refractory organics. The degradation reaction of organic compounds and persulfate generation reaction occur simultaneously in Pt anodic oxidation system with electrolyte of Na

Spectroscopic, thermal and magnetic properties of some transition metal complexes derived from 1-Phenyl-3-Substituted-4-Nitroso-5-Pyrazolones

Complexes derived from some 1Phenyl3meth yl4nitroso5pyrazolone (L1), 1,3diphenyl4 nitroso5pyrazolone (L2) and 1phenyl3anilino 4nitroso5pyrazolone (L3) with Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ metal ions have been prepared. Structural investigation of the ligands and their complexes has been made based on elemental analysis, infrared (FTIR), ultraviolet and visible spectra (UVVis.), proton nuclear magnetic reso nance (1H NMR), magnetic susceptibility (?eff.) and thermal analysis (TG and DTG). The effect of solvents has been carried out in organic solvents of varying polarity. The observed transition energy and oscillator strengths were also calculated. The data obtained show that all of the prepared complexes contain water molecules in their coordination sphere. The investigated ligands acts as neutral bidentate ligands bonded to the metal ions through the two oxygen atoms of the carbonyl and nitroso groups. The isolated complexes behave as nonelectro lyte in DMF solution. The Mn2+, Co2+, Ni2+ and Cu2+ complexes show high spin configurations as the ground state. The high spin values of ma gnetic susceptibility may be due to the ligands being weak ligands. The Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ complexes exhibit an octahedral or distorted octahedral coordination with the investigated ligands.

Initiation time of post-ischemic hypothermia on the therapeutic effect in cerebral ischemic injury

Objective: To study the efficacy of mild brain hypothermia beginning at different time intervals on cerebral ischemic injury.Methods: Male Sprague–Dawley rats were divided into sham-operated group, normothermia (37–38°C) and mild hypothermia (31–32°C) ischemia groups. The last group was subdivided into four groups: 240 minute hypothermia, 30 minute normothermia plus 210 minute hypothermia, 60 minute normothermia plus 180 minute hypothermia, and 90 minute normothermia plus 150 minute hypothermia (n=8). Global cerebral ischemia was established using the Pulsinelli four-vessel occlusion model for 20 minutes and mild hypothermia was applied after 20 minutes of ischemia. Brain tissue was collected following 20 minute cerebral ischemia and 240 minute reperfusion, and used to measure the levels of malondialdehyde (MDA), lactate, water content and the amounts of electrolytes, such as sodium (Na+), potassium (K+) and calcium (Ca++).Results: Mild hypothermia beginning at 0–60 minutes decreased the levels of malondialdehyde and lactate (p<0.05 or p<0.01), decreased water content, Na+ and Ca++, and increased the amount of K+ (p<0.05 or p<0.01) in ischemic tissue, except the amounts of Na+, K+ and Ca++ in mild hypothermia beginning at 60 minute ischemia group (p>0.05). Mild hypothermia beginning at 90 minutes had little effect on the levels of targeted molecules, water content and amounts of electrolytes of Na+, K+ and Ca++ in ischemic tissue (p>0.05).Discussion: Post-ischemic mild brain hypothermia can decrease the accumulation of lactate and lipid peroxidation in ischemic tissue, and delay the development of brain edema following ischemic reperfusion. The best neuroprotection of mild hypothermia to attenuate ischemic injury was begun within 60 minutes.

SYNTHESIS, CHARACTERIZATION, AND BIOLOGICAL ACTIVITIES OF SCHIFF BASE COMPLEXES DERIVED FROM METHYL-SUBSTITUTED SALICYLALDEHYDE AND D-GLUCOSAMINE, ML2 (M=Cu (II), Zn(II), Fe(II), Co (II), Ni(II); L=3- OR 4-METHYLSALICYLALDEHYDE D-GLUCOSEIMINE)

ABSTRACT Two new Schiff base ligands (3-MeSGH and 4-MeSGH) derived from methyl-substituted salicylaldehyde (MeS) and D-glucosamine (GA), and ten of their metal complexes ML2 (M= Cu(II), Zn(II), Fe(II), Co(II), Ni(II); HL=3-MeSGH or 4-MeSGH) were prepared and characterized by elemental analyses, infrared and electronic spectra, molar conductivity measurements and magnetic moments at room temperature. The Schiff base ligands and the zinc(II) complexes were further characterized by 1H and 13C NMR. The copper(II) complexes were also characterized by ESR. All the complexes are non-electroly tes and superoxide free radical scavengers.