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At least 253 records · Page 14

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DOE OSTI2026

Structuring, stochastic behavior, and charge storage capacity of redox-active microemulsions formulated with mixtures of toluene and ionic liquid as oil phase

Oil/water microemulsions (µEs) are promising electrolytes for redox flow batteries (RFBs) as they simultaneously improve charge capacity and ionic conductivity. Here, we report the successful formulation of bicontinuous µEs where the oil phase is a solution of trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)amide ionic liquid in toluene with redox-active ferrocene. We examined the effect of supporting electrolyte anion (NO 3 – , Cl – , ClO 4 – ) on the structure, reactivity, transport, and electrolytic performance of redox-active µEs. Neutron scattering and nuclear magnetic resonance showed that the domain size increased as Cl – > NO 3 – > ClO 4 – while the ferrocene diffusion coefficient increased as NO 3 – > Cl – > ClO 4 – . Scanning electrochemical microscopy indicated anion-dependent current fluctuations during electrolysis, with ClO 4 – exhibiting the least high-frequency oscillations, which correlate to the highest charge and discharge capacity and reversibility. All ionic liquid containing systems improved the performance of toluene-based µEs, highlighting new design principles for these electrolytes.

diffusion↗

DOE OSTI2020

Influence of Water Transport Across Microscale Bipolar Interfaces on the Performance of Direct Borohydride Fuel Cells

Direct borohydride fuel cells (DBFCs) can operate at double the voltage of proton exchange membrane fuel cells (PEMFCs) by employing an alkaline NaBH 4 fuel feed and an acidic H 2 O 2 oxidant feed. The pH-gradient-enabled microscale bipolar interface (PMBI) facilitates the creation and maintenance of an alkaline environment at the anode and an acidic environment at the cathode for the borohydride oxidation and peroxide reduction reactions. However, given the need to dissociate water at the interface to ensure ionic conduction, PMBI can be efficient only when anion exchange ionomer (AEI) moieties enable fast water transport for autoprotolysis. Herein, a series of polynorbornene-based AEIs with a range of water uptake values are examined to unravel the optimum water uptake required to enable high performance DBFCs. The DBFC with PMBI configuration containing the optimal AEI composition delivers a current density of 302 mA cm –2 at 1.5 V and a peak power density of 580 mW cm –2 at 1 V. This AEI composition exhibits high hydroxide ionic conductivity of 90.7 mS cm –1 at 80 °C with an IEC of 2.01 mequiv g –1 and demonstrates impressive chemical stability by retaining 98.75% of its initial ionic conductivity after immersion into anolyte (3 M KOH and 1.5 M NaBH 4 ) at 70 °C for 536 h.

25 ENERGY STORAGE↗

DOE OSTI2021

Electrolytes, current collectors, and binders for rechargeable metal-ion batteries

A metal-ion battery includes: 1) an anode including a metal; 2) a cathode; and 3) an ionic liquid electrolyte disposed between the anode and the cathode, wherein the ionic liquid electrolyte corresponds to a mixture of a metal halide and an organic compound.

Dai, Hongjie↗

DOE OSTI2024

Promoting electrochemical rates by concurrent ionic-electronic conductivity enhancement in high mass loading cathode electrode

Enhancing the fast charging capacity of thick electrodes with high mass loading is imperative in expediting the widespread adoption of electric vehicles. Nonetheless, the insufficient charge transfer kinetics of thick electrodes hinder the movement of effective electrons and ions, hence diminishing capacity at high current rates. In this work, we applied sustainable and biodegradable cellulose nanocrystals (CNCs) as electrode additives. It is the first time to simultaneously improve the electronic conductivity by optimizing the carbon dispersion and establishing electron transfer networks, as well as boosting the ionic conductivity of electrodes by shortening the ion transfer pathway. Specifically, the LiNi 0.6 Mn 0.2 Co 0.2 O 2 electrodes incorporating 1% dual functional CNCs additive exhibit improved effective electrical conductivity from 0.11 to 0.16 S/m and risen effective ionic conductivity from 0.36 to 0.62 S/m, in comparison to counterpart electrodes without CNCs. Therefore, the 1% CNC electrode with a high mass loading of 27.0 mg/cm 2 delivers a discharge capacity of 128 mAh/g at 1 C, which is superior to that of the CNC-free electrodes (95 mAh/g). In short, this study presents a novel environmentally friendly, economically viable, and dual-functional electrode additive that enhances both electronic and ionic conductivities with the aim of facilitating the widespread adoption of fast-charging high mass loading electrodes.

25 ENERGY STORAGE↗

NASA NTRS1990

MIS capacitor studies on silicon carbide single crystals

Cubic SIC metal-insulator-semiconductor (MIS) capacitors with thermally grown or chemical-vapor-deposited (CVD) insulators were characterized by capacitance-voltage (C-V), conductance-voltage (G-V), and current-voltage (I-V) measurements. The purpose of these measurements was to determine the four charge densities commonly present in an MIS capacitor (oxide fixed charge, N(f); interface trap level density, D(it); oxide trapped charge, N(ot); and mobile ionic charge, N(m)) and to determine the stability of the device properties with electric-field stress and temperature. The section headings in the report include the following: Capacitance-voltage and conductance-voltage measurements; Current-voltage measurements; Deep-level transient spectroscopy; and Conclusions (Electrical characteristics of SiC MIS capacitors).

Kopanski, J. J.↗

DOE OSTI2024

CONVENTIONAL SUPERCAPACITOR ELECTROLYTES: AQUEOUS, ORGANIC, AND IONIC

This chapter thoroughly covers the most recent developments of aqueous and non-aqueous electrolytes for electrochemical supercapacitors (ESs). In more detail, the overview of different types of electrolytes and their featured properties are initially introduced. Thereafter, the conventional aqueous electrolyte was first discussed, summarized, and opened the perspectives of some new salts that can be used to enhance the ionic conductivity and the performance of supercapacitor. The organic electrolytes, including the organic solvents/salt, ionic liquids, and deep eutectic, are the main parts to explore different trends and cutting-edge advances in optimizing electrolyte formulations customized for different electrode materials. Furthermore, the discussion on the current obstacles and prospects of these electrolytes is also underlined.

electrochemical capacitors, aqueous electrolyte, o↗

DOE OSTI2024

Hyperconjugation-controlled molecular conformation weakens lithium-ion solvation and stabilizes lithium metal anodes

Tuning the solvation structure of lithium ions via electrolyte engineering has proven effective for lithium metal (Li) anodes. Further advancement that bypasses the trial-and-error practice relies on the establishment of molecular design principles. Expanding the scope of our previous work on solvent fluorination, we report here an alternative design principle for non-fluorinated solvents, which potentially have reduced cost, environmental impact, and toxicity. By studying non-fluorinated ethers systematically, we found that the short-chain acetals favor the [gauche, gauche] molecular conformation due to hyperconjugation, which leads to weakened monodentate coordination with Li + . The dimethoxymethane electrolyte showed fast activation to >99% coulombic efficiency (CE) and high ionic conductivity of 8.03 mS cm -1 . The electrolyte performance was demonstrated in anode-free Cu$∥$LFP pouch cells at current densities up to 4 mA cm -2 (70 to 100 cycles) and thin-Li$∥$high-loading-LFP coin cells (200–300 cycles). Overall, we demonstrated and rationalized the improvement in Li metal cyclability by the acetal structure compared to ethylene glycol ethers. We expect further improvement in performance by tuning the acetal structure.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

NASA NTRS1973

The charge composition aspect of energetic trapped particles

Three possible sources of particle species important to the energy balance of the magnetosphere are discussed, with special emphasis on particles with different charge-to-mass ratios. Possibilities for various experimental tests are pointed out. Some recent experimental data on geomagnetically trapped alpha particles are compared with relevant results of current theoretical work. An experiment is proposed that is likely to provide quantitative indications for the energization and loss processes affecting ionic particle species in the magnetosphere.

Krimigis, S. M.↗

DOE OSTI2021

Optoelectronic memristor devices including one or more solid electrolytes with electrically controllable optical properties

An optoelectronic memristor includes a first electrode, a second electrode, and a solid electrolyte in between that is in electrical communication with the first electrode and the second electrode. The solid electrolyte has an electronic conductivity of about 10 −10 Siemens/cm to about 10 −4 Siemens/cm at room temperature. The first electrode, and optionally the second electrode, can be optically transparent at a specific wavelength and/or a wavelength range. A direct current (DC) voltage source is employed to apply an electric field across the solid electrolyte, which induces a spatial redistribution of ionic defects in the solid electrolyte. In turn, this causes a change in electrical resistance of the solid electrolyte. The application of the electric field can also cause a change in an optical property of the solid electrolyte at the specific wavelength, and/or at the wavelength range (or a portion thereof).

Defferriere, Thomas↗

DOE OSTI2022

Polybenzimidazole (PBI) membranes for redox flow batteries

Disclosed are redox flow battery membranes, redox flow batteries incorporating the membranes, and methods of forming the membranes. The membranes include a polybenzimidazole gel membrane that is capable of incorporating a high liquid content without loss of structure that is formed according to a process that includes in situ hydrolysis of a polyphosphoric acid solvent. The membranes are imbibed with a redox flow battery supporting electrolyte such as sulfuric acid and can operate at very high ionic conductivities of about 100 mS/cm or greater. Redox flow batteries incorporating the PBI-based membranes can operate at high current densities of about 100 mA/cm2 or greater.

Benicewicz, Brian C.↗

DOE OSTI2023

Polybenzimidazole (PBI) membranes for redox flow batteries

Benicewicz, Brian C.↗

DOE OSTI2023

Applications of biomass-derived solvents in biomass pretreatment – Strategies, challenges, and prospects

We report biomass pretreatment is considered a key step in the 2nd generation biofuel production from lignocellulosic biomass. Research on conventional biomass pretreatment solvents has mainly been focused on carbohydrate conversion efficiency, while their hazardousness and/or carbon intensity were not comprehensively considered. Recent sustainability issues request further consideration for eco-friendly and sustainable alternatives like biomass-derived solvents. Carbohydrate and lignin-derived solvents have been proposed and investigated as green alternatives in many biomass processes. In this review, the applications of different types of biomass pretreatment solvents, including organic, ionic liquid, and deep eutectic solvents, are thoroughly discussed. The role of water as a co-solvent in these pretreatment processes is also reviewed. Finally, current research challenges and prospects of utilizing biomass-derived pretreatment solvents for pretreatment are discussed. Given bioethanol's market potential and increasing public awareness about environmental concerns, it will be a priority adopting sustainable and green biomass pretreatment solvents in biorefinery.

09 BIOMASS FUELS↗

NASA NTRS2018

Ionic Liquid Facilitated Recovery of Metals and Oxygen from Regolith

Regolith, being largely composed of metal oxides, has the potential to be an excellent in situ source of metals, such as iron, nickel and aluminum, as well as oxygen. There is, however, no current technology that is suited for the in space separation of metal oxides into their constituent elements. Terrestrial methods require large volumes/masses of hazardous reagents. Alternative methods, such as molten oxide electrolysis, have been investigated, but these processes generally require high temperatures to operate. Such a requirement imposes significant material compatibility restraints, necessitates high energy inputs, and may pose a threat to the health and safety of the crew. This paper discusses a novel process that uses ionic liquids (ILs) to recover high purity metals and oxygen from regolith and meteorite materials. ILs are organic salts that are molten at or near room temperature, and can have a number of attractive properties including wide liquidus ranges and high thermal and electrochemical stability. The structure of an IL can be readily modified to tune these properties, allowing the synthesis of task specific ILs. Together, these attributes give ILs great utility in a number of space related areas, such environmental control and life support, in space repair and manufacture, and in situ resource utilization.

Karr, Laurel J.↗

DOE OSTI2026

Quantification of [MTBD][beti] loading and its effects on Pt/HSC electrode performance in hydrogen fuel cells

High surface area carbon-supported platinum catalysts (Pt/HSC) are widely used in polymer electrolyte membrane fuel cells but often suffer from limited proton and oxygen transport within porous domains. To address these challenges, we integrate the ionic liquid [MTBD][beti] into Pt/HSC catalyst layers using two deposition methods-one-pot and sequential deposition-to tune IL distribution within micropores and mesopores. A combination of ex situ and in operando techniques were employed to elucidate electrode structure-performance relationships across a range of IL loadings. Sequential deposition achieved more efficient pore filling and higher IL retention at lower IL:C ratios, enabling enhanced proton conductivity and protection of active sites. Compared to the IL-free Pt/HSC, IL-modified electrodes demonstrated up to 28% improvement in mass activity and enhanced high-current-density performance under low relative humidity, while maintaining comparable performance under humidified conditions. Electrochemical impedance spectroscopy and CO displacement experiments reveal that improvements are linked to reduced ionic resistance and lower sulfonate adsorption on Pt sites, rather than changes in electrochemical surface area. However, excessive IL loading leads to mass transport losses. These results highlight the importance of selective pore filling and efficient IL distribution in achieving kinetic gains without compromising ionic and gas transport.

08 HYDROGEN↗

DOE OSTI2026

Deciphering the Dynamic Balance Between Solvation Strength and Polysulfides Reaction Heterogeneity in Practical Lithium‐Sulfur Batteries

Achieving stable interfacial chemistry in lithium–sulfur batteries under practical conditions remains a key barrier to commercialization. Here, we demonstrate that interfacial dynamics can be effectively regulated by coupling solvation-power control with intrinsic heterogeneity of sulfur redox chemistry through the introduction of a weakly solvating fluorinated cosolvent, LIB 1200ET (1200ET). Compared with conventional fluorinated ethers, 1200ET efficiently shifts Li + solvation environment toward a more non-coordinated configuration at low volume fractions, enabling substantial solvation modulation without significantly impairing sulfur redox kinetics. This solvation transition weakens Li + –solvent interactions while strengthening Li + –anion and Li + –lithium polysulfide (LPS) coordination, suppressing LPS solubility and promoting reconstruction of solid–electrolyte interphase (SEI). Regulated LPS chemistry, together with 1200ET, leads to formation of a S 4+ -rich, LiF-reinforced SEI with enhanced ionic conductivity and mechanical robustness. Spatially resolved sulfur K-edge X-ray absorption spectroscopy on pouch cells reveals pronounced current-density-dependent chemical heterogeneity, distinguishing kinetically dominated and solvation-controlled regions. Under practical conditions (3.7 mg cm −2 sulfur loading, E/S = 6 µL mg −1 ), a single-layer pouch cell delivers 527 mAh g −1 over 200 cycles at C/3, while an Ah-level multilayer pouch cell achieves an energy density of 358 Wh kg −1 . These results establish non-coordinating cosolvent-driven solvation engineering as a scalable strategy for practical Li–S batteries.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Bridging Atomic Solvation Environment with Electrochemical Properties for the Bis(trifluoromethylsulfonyl)imide-Based Divalent Cation Electrolytes for the Next-Generation Energy Storage Systems

A deep molecular-level understanding of the multivalent electrolyte and its correlation with the electrochemical properties is crucial for designing optimized electrolytes for next-generation rechargeable batteries. Comprehensive knowledge of the atomic level of the solvation structure and its connection with electrochemical stability and ion transport properties is especially critical. However, the interaction of these three components coupled with clear atomistic insights is lacking in the literature. Here, our current contribution evaluates representative electrolytes with the bis(trifluoromethanesulfonyl)imide (TFSI) anions for multivalent cations of Mg, Ca, and Zn, at different ionic conditions with and without a cosolvated environment in ether-based solvent. Two critical problems are investigated: first, resolving the solvation structures in the electrolyte solutions as a function of concentrations through pair distribution function analysis and the corresponding electrochemical transport properties; second, unmasking the quantitative correlation of the atomistic environment with both electrochemical kinetics and cation dependence. We discovered that the magnesium- and calcium-based electrolytes display versatile coordination lengths but poor average anodic stability due to ion pairing with TFSI - . On the contrary, the zinc-based electrolytes show the shortest solvent coordination lengths, shielding the Zn cation from rigid solvent interactions and resulting in the highest anodic stabilities. Calcium-based electrolytes exhibit the longest and most concentration-independent coordination lengths. This work provides valuable insights into the molecular structural and electrochemical features of diverse multivalent electrolyte systems with cations in various solvation environments, emphasizing the importance of the solvation structure and construction in designing high-performance electrolytes.

cation coordination↗

DOE OSTI2020

Corrosion of Commercial Mg–Al Alloys: AZ31B, AM60, and AZ91D

Aqueous corrosion, atmospheric corrosion, and ionic liquid dissolution studies were performed on commercial alloys AZ31B, AM60, and AZ91D and compared with previously reported results for single-phase binary Mg–Al alloys containing similar Al concentrations (αMg-2 at% Al, αMg-5 at% Al, and Mg-8 at% Al). Polarization studies in 0.6 M NaCl were used to characterize the aqueous free corrosion behavior during 20-h free immersion. Accelerated corrosion testing was performed using a rotating-disk electrode which revealed the evolution of an Al-rich mud-cracking and platelet morphology. Atmospheric droplet testing showed rapid pH increases that depended on the Al concentration in the alloy. Time-dependent contact angle measurements showed that the degree of droplet wetting increased during free corrosion by ~50° over 20 h in 0.6 M NaCl. Ionic liquid dissolution studies in 1:2 M choline chloride:urea deep eutectic solvent were performed in order to examine the current-voltage behavior of these alloys in the absence of water and hydrogen reduction. The results of these studies revealed the formation of nanowire corrosion morphologies within a honeycomb lattice structure which we attribute to selective dissolution of Mg via a two-dimensional stepflow process

25 ENERGY STORAGE↗

NASA NTRS1983

Ionic composition of the earth's radiation belts

Several different ion species have been positively identified in the earth's radiation belts. Besides protons, there are substantial fluxes of helium, carbon and oxygen ions, and there are measurable quantities of even heavier ions. European, American and Soviet space experimenters have reported ion composition measurements over wide ranges of energies: at tens of keV (ring-current energies) and below, and at hundreds of keV and above. There is still a gap in the energy coverage from several tens to several hundreds of keV where little observational data are available. In this review emphasis is placed on the radiation belt ionic structure above 100 keV. Both quiet time conditions and geomagnetic storm periods are considered, and comparison of the available space observations is made with theoretical analysis of geomagnetically trapped ion spatial, energy and charge state distributions.

Spjeldvik, W. N.↗