Impact Of Electrolyte Composition Research Articles

To achieve fast ion transport of engineered electrolyte and ultra-high rate of defected Nb16W5O55-based anode

The maximum output power and minimum charge time of a lithium-ion battery depend on ion transport and electron transport. The electron conduction/ion diffusion within the electrochemically active materials and the ion mobility of the electrolyte usually represent the fundamental limits of the battery charge and discharge rates. Nb16W5O55 is notable for its exceptional lithium-ion mobility and high electronic conductivity, making it a popular choice for fast-charging anode materials. However, the lithium-ion diffusion capability of the electrolyte is also crucial in determining the overall fast-charging performance of the battery. This can be a limiting factor for Nb16W5O55-based batteries. This work delves into the impact of electrolyte composition on fast-charging performance by examining the electrochemical properties of electrolytes with varying concentrations, in conjunction with molecular dynamics simulation. Specifically, increasing the concentration of LiTFSI salt alters the solvation structure of lithium ions due to the increasing coordination numbers of TFSI− and Li+, which hampers lithium-ion diffusion. Additionally, low-concentration electrolytes struggle with rapid mass transfer due to fewer lithium-ion carriers, limiting ultra-high-rate performance. To address these challenges, the solvation structure of the electrolyte was optimized, leading to enhanced fast-charging and discharging performance.

Impact of Electrolyte Composition on Bulk Electrolysis of Furfural over Platinum Electrodes**

AbstractPartial oxidation of furanic biomass derivatives such as furfural is of interest for the sustainable production of chemicals including furoic acid, maleic acid, and 2,5‐furandicarboxylic acid (FDCA). The oxidative bulk electrolysis of furfural is here investigated on platinum electrodes in acidic media. The effects of potential, concentration, pH, and supporting anion are studied, and selectivity trends are coupled with attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) to illuminate adsorbate structures that influence the catalysis. Increasing potential is found to shift selectivity from primarily C5 products to C4 products, coincident with oxidation of the Pt surface. Selectivity changes are also observed moving from pH 1 to pH 4, with an increase in C5 products at higher pH. Changing from the weakly adsorbing perchlorate anion to the specifically‐adsorbing phosphate anion results in a number of changes that manifest differently depending on potential and pH. Selectivity to furoic acid is found to be highest above the pKa of phosphoric acid due to the strongly adsorbed phosphate ions suppressing flat‐lying configurations of furfural that lead to C−C cleavage. These results point toward opportunities to use electrolyte engineering to tune selectivity and optimize surface conditions to disfavor binding of inhibitory products.

Mechanism of Bismuth Stimulated Bottom-up Gold Feature Filling

The mechanism underlying -stimulated bottom-up Au filling and self-passivation in trenches and vias in slightly alkaline electrolytes is explored. The impacts of electrolyte components and and potential-dependent kinetic factors on the rate of Au electrodeposition are quantified experimentally. Derived parameters are applied within the surfactant conservation Curvature Enhanced Accelerator Coverage model to simulate the filling of high aspect ratio trenches. It is observed that Bi adsorption accelerates the Au deposition rate with a non-linear dependence occurring around a critical coverage. Further, the impact of electrolyte composition is such that gradients of and derived from reduction of during deposition accentuate deposition farther from the feature opening. These factors and surface area reduction result in Bi enrichment at the bottoms of filling features that localizes active deposition to feature bottoms. Ultimately, weakening of the concentration gradients and associated kinetics as bottom-up feature filling progresses reduces the Bi coverage on the growth front below the critical value and bottom-up growth terminates. Good agreement is observed with key experimental features including the incubation period of conformal deposition, transition to bottom-up growth, subsequent bottom-up filling and finally self-passivation as the growth front nears the field.

A Comprehensive Study on Synthesis Parameters of TiO2 Nanotube Arrays: The Effects on Morphology and Photocatalytic Degradation of Para-NitroPhenol

The present research aimed to evaluate the effects of synthesis parameters on morphology and photocatalytic activity of TiO2 nanotube aligned arrays (TNAs) via a low cost anodization process. The impact of electrolyte composition, anodization time, as well as applied voltage on morphological and architecture properties of TNAs including; length, inner diameter, and wall thickness were accurately investigated. We further studied effect of heat treatment on crystalline and phase transformation of the samples at different annealing temperatures. Photocatalytic properties of the fabricated samples were studied for degradation of p-nitrophenol under UV light irradiation. Physical/chemical characteristics of the photo-anodes were observed using several techniques including field emission scanning electron microscopy (FE-SEM) , Energy Dispersive X-Ray Spectroscopy (EDX) and XRD . Moreover, the maximum photocatalytic performance for p-nitrophenol degradation was obtained as about 80%.

(Charles W. Tobias Young Investigator Award Address) Understanding Reactivity at Electrode-Electrolyte Interfaces in Li-O2 and Li-ion Batteries

When expanding the limits of voltage stability, capacity retention, and rate capability in batteries, parasitic processes at electrode-electrolyte interfaces-- such as electrolyte degradation, oxide surface densification, and Li metal plating on graphite electrodes-- play a critical role in defining battery performance. Our laboratory’s objective is to combine quantitative analytical techniques with spectroscopy to understand, and ultimately suppress, these process’s role in observed system lifetime, capacity, and efficiency. This presentation will provide a perspective on our understanding of interfacial reactivity in two systems: the positive electrode in the nonaqueous metal-O2 batteries, and interfaces in Li-ion batteries operating at either high voltage or high rates. First, the impact of electrolyte composition on product formation mechanisms in metal-O2 batteries will be discussed, as will strategies to suppress reactive oxygen-induced degradation. Second, drawing a comparison to Li-O2 batteries, the influence of anionic oxygen redox in interfacial degradation processes will be discussed in emerging high-capacity cathode materials, such as cation disordered rocksalt oxide and oxyfluoride materials and Ni-rich NMC layered oxide materials. Finally, to highlight the versatility of gas evolution-based quantitative techniques developed to study oxygen activity in metal-O2 and Li-ion oxide cathodes, the accurate detection of Li plating onset during fast charging of graphite electrodes will be shown by monitoring hydrogen evolution upon exposure of nominally delithiated graphite electrodes to acid.

Impact of Electrolyte Composition and Modes of Operation on the Structure, Morphology, and Properties of Oxide Ceramic Coatings Fabricated by Microarc Oxidation

The formation of oxide coatings on D16 aluminum alloy by microarc oxidation (MAO) treatment in the anodal-cathodal mode with discharge interruption in the basic silicate-alkali electrolyte (composed of three solutions) and in the mode without charge interruption in a silicate-alkali electrolyte of similar composition is studied. We find that the mechanism of formation of oxide ceramic coatings depends on the mode of MAO treatment. Addition of sodium tetraborate to the electrolyte has an impact on the properties of oxide ceramic coatings fabricated using the mentioned treatment modes. We demonstrate that MAO treatment in the anodal-cathodal mode with discharge interruption gives rise to a higher content of high-temperature aluminum oxide phase (α-Al2O3) in coatings and enables the formation of thin (up to 25 μm) oxide ceramic coatings that retain all unique properties of this type of coatings.

Impact of electrolyte composition on the reactivity of a redox active polymer studied through surface interrogation and ion-sensitive scanning electrochemical microscopy.

Elucidating the impact of interactions between the electrolyte and electroactive species in redox active polymers is key to designing better-performing electrodes for electrochemical energy storage and conversion. Here, we present on the improvement of the electrochemical activity of poly(para-nitrostyrene) (PNS) in solution and as a film by exploiting the ionic interactions between reduced PNS and K(+), which showed increased reactivity when compared to tetrabutylammonium (TBA(+))- and Li(+)-containing electrolytes. While cyclic voltammetry enabled the study of the effects of cations on the electrochemical reversibility and the reduction potential of PNS, scanning electrochemical microscopy (SECM) provided new tools to probe the ionic and redox reactivity of this system. Using an ion-sensitive Hg SECM tip allowed to probe the ingress of ions into PNS redox active films, while surface interrogation SECM (SI-SECM) measured the specific kinetics of PNS and a solution phase mediator in the presence of the tested electrolytes. SI-SECM measurements illustrated that the interrogation kinetics of PNS in the presence of K(+) compared to TBA(+) and Li(+) are greatly enhanced under the same surface concentration of adsorbed radical anion, exhibiting up to a 40-fold change in redox kinetics. We foresee using this new application of SECM methods for elucidating optimal interactions that enhance polymer reactivity for applications in redox flow batteries.

Electrochemical Performance of Plasma Sprayed Metal Supported Planar Solid Oxide Fuel Cells

High production cost is one of the major barriers to widespread commercialization of solid oxide fuel cells (SOFCs). Thermal spray techniques are a low cost alternative for the production of SOFCs. The objective of this work was to evaluate the electrochemical performance of cells produced by plasma spraying. The anode was deposited on a porous metallic support by atmospheric plasma spraying (APS) whereas the electrolyte was deposited by plasma spray-thin film (PS-TF) technique, which can produce thin and dense coatings at high deposition rates. The cathode was deposited by screen-printing and in-operando sintering. The electrochemical tests were performed at 650–800°C. Current-voltage characteristics and impedance spectra were measured and analyzed. The impact of electrolyte composition and layer thickness on the gas tightness of the electrolyte and the area specific resistance of the cell is discussed. The results show that the applied thermal spraying techniques are a potential alternative for producing SOFCs.

The Impact of Electrolyte Composition on Parasitic Reactions in Lithium Ion Cells Charged to 4.7 V Determined Using Isothermal Microcalorimetry

In an effort to better the understanding of the high voltage degradation of electrolytes in lithium ion cells, this work presents isothermal microcalorimetry results on LiNi0.42Mn0.42Co0.16O2 (NMC442)/graphite pouch cells up to 4.7 V. The voltage and time dependent parasitic heat flow was determined for cells containing several electrolyte compositions based on carbonate solvents with several additive combinations, as well as a fluorinated carbonate solvent system. We have demonstrated that cells containing fluorinated carbonate-based electrolyte (1M LiPF6 in 3:7 fluoroethylene carbonate: di-2,2,2-trifluoroethyl carbonate) showed a significantly decreased parasitic heat flow at voltages >4.4 V compared to ethylene carbonate-based cells, but limited advantage <4.4 V. However all cells, regardless of electrolyte composition, exhibited very large parasitic heat flows, and therefore parasitic reaction rates, at high voltages (>4.35 V). The results presented here also show that high voltage (>4.5 V) cycling results in an increase in parasitic heat flow of the subsequent lower voltage cycles, and is indicative of a change in the dominant reaction pathway.

Electrochemical Performance of Plasma Sprayed Metal Supported Planar Solid Oxide Fuel Cells

High production cost is one of the major barriers to widespread commercialization of solid oxide fuel cells (SOFCs). Thermal spray techniques are a low cost alternative for the production of SOFCs. The objective of this work was to evaluate the electrochemical performance of half-cells produced by plasma spraying. The anode was deposited on a porous metallic support by atmospheric plasma spraying (APS) whereas the electrolyte was deposited by plasma spray-thin film (PS-TF) technique which can produce thin and dense coatings at high deposition rates. The cathode was deposited by screen-printing. The electrochemical tests were performed at 650-800°C. Current-voltage characteristics and impedance spectra were measured and analyzed. The impact of electrolyte composition and layer thickness on the gas tightness of the electrolyte and the area specific resistance of the cell is discussed. The results show that the applied thermal spraying techniques are a potential alternative for producing SOFCs.

Polymer anion-selective membrane for electrolytic water splitting: The impact of a liquid electrolyte composition on the process parameters and long-term stability

In the present study the impact of KOH replacement by a NaHCO3 or Na2CO3 solution on the performance of alkaline water electrolysis and the life-time of an anion-selective polymer electrolyte was assessed. In the first instance, the impact of the electrolyte composition on the kinetics of the electrode reactions was studied. Subsequently the ionic conductivity of the membrane, in the form of individual anions, and the efficiency of the alkaline water electrolysis process were evaluated by means of electrochemical impedance spectroscopy and a laboratory single-cell alkaline water electrolyzer. The anion used was observed to make a significant impact both on the ionic conductivity as well as on the kinetics of the anode reaction, resulting in reduced electrolysis efficiency. A stability test revealed kinetics of chemical degradation of the polymer anion-selective membrane in a Na2CO3 solution similar to those in a KOH environment at 70 °C. An alternative approach of decreasing the temperature to 50 °C prolonged the chemical stability and made less impact on the process efficiency.

Impact of electrolyte composition on the performance of the zinc–cerium redox flow battery system

The zinc–cerium redox flow battery has the highest open circuit cell voltage (Ecell = 2.4 V) of all the common redox flow battery (RFB) systems being investigated. In this paper, carbon polymer composite materials based on polyvinyl ester and polyvinylidene difluoride are investigated as the negative electrode for this RFB system. Electrolyte composition, particularly on the negative side, is found to play a key role in maintaining high (∼90%) coulombic efficiencies for the different charge durations, from 10 min to 4 h, examined. Energy efficiencies >60% are obtained for temperatures in the range 45 °C–55 °C when the zinc ion concentration in the methanesulfonic acid electrolyte is 2.5 mol dm−3. No dependence of the energy efficiency on the flow velocity is found, over the range 7.5 cm s−1–13.5 cm−1.