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At least 181 records · Page 10

All sources NASA NTRS DOE OSTI

DOE OSTI2025

Structure, dynamics, and electrochemistry of choline chloride/ethylene glycol eutectic solvents at an electrode surface explored by molecular dynamics simulations

Choline chloride and ethylene glycol mixtures with 1:2, 1:4, and 1:6 molar ratios on the surfaces of graphite and gold electrodes were studied using classical molecular dynamics simulations. Both neutral and charged electrodes were considered. The liquid composition, solvation structure, molecular orientation, and dynamics at the electrode surface are significantly different from those of the bulk liquid. These properties strongly depend on the electrode material and charge density, whereas they are less sensitive to the overall solvent composition. The effect of the electrode on the composition, structure, and orientation of the liquid fades beyond ∼10 Å from the surface of the electrode. This distance corresponds to about two layers of the structured solvent, despite the fact that the layered structure extends to at least five layers or about 25 Å. However, the electrode influences solvent dynamics over a longer distance. The electrochemical properties of the eutectic solvent at both electrode surfaces were also studied. The simulations captured the experimental differential capacitance shapes for both electrode systems, although the magnitudes and exact shapes differ. The simulations further revealed that the solvent in the first solvation layer can both overscreen and underscreen the electrode charges depending on the electrode material and electrode potential.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2020

Passive magnetic devices

A passive magnetic device (PMD) has a base electrode, a multi-port signal structure (MPSS), and a substrate therebetween. The MPSS has a central plate residing in a second plane and at least two port tabs spaced apart from one another and extending from the central plate. The substrate has a central portion that defines a mesh structure between the base electrode and the central plate of the multi-port signal structure. A plurality of magnetic pillars are provided within the mesh structure, wherein each of the plurality of the magnetic pillars are spaced apart from one another and surrounded by a corresponding portion of the mesh structure. The PMD may provide a magnetically self-biased device that may be used as a radio frequency (RF) circulator, an RF isolator, and the like.

42 ENGINEERING↗

DOE OSTI2020

Passive magnetic devices

Ketterson, Andrew Arthur↗

DOE OSTI2026

Multiscale Cryo Electron Microscopy Reveals Interfacial Degradation and Stabilization in Battery Electrodes

Electrochemical interfaces are dynamic systems, evolving based on their local environment and reactant surface structures. The electrode-electrolyte interface in Li-ion batteries can be protective, limiting parasitic reactions with the electrolyte to passivate the surface [1]. Additionally, this interphase has an impact on the Li-ion transport through that layer based on its composition, bonding environment, and thickness. These parameters are challenging to collect and may vary depending on the electrode surface site investigated relative to its spatial position in a coin cell. This study will detail a multiscale cryogenic electron microscopy approach where millimeter-scale cross-sections through the coin cell batteries were made using a cryogenic stage within a fs-laser plasma focused ion beam (laser PFIB) with complementary energy dispersive X-ray spectroscopy able to detect variations in the composition at electrode interfaces [2]. Microscale cross-sectioning and lamella sample preparation of battery electrodes was conducted at the Center for Integrated Nanotechnologies using a Ga-ion focused ion beam (FIB) with air-free and cryo-transfer [3], followed by nanoscale mapping of composition and bonding within the CEI through cryo-scanning transmission electron microscopy (cryo-STEM) electron energy loss spectroscopy [4]. This multiscale approach enabled identification of millimeter-scale features of a battery stack with visualization of degradation in electrodes such as cracks in cathode particles, gas evolution, and SEI evolution; microscale interfacial characteristics, such as heterogeneity in the SEI or barrier layer and identification of electrolyte networks to the electrode surfaces; and nanoscale measurement of the CEI thickness, mapping of transition metal bonding within the cathode particles to identify loss of active materials, and identification of beneficial electrolyte additives incorporated into the CEI structure. This multiscale approach allows for a statistical understanding of the primary mechanisms and parasitic degradation pathways that impact performance by limiting the ion transport pathways within Li+ batteries.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Extreme Fast Charging: Effect of Positive Electrode Material on Crosstalk

Extreme fast charging (XFC) is a key requirement for the adoption of battery-based electric vehicles by the transportation sector. However, XFC has been shown to accelerate degradation, causing the capacity, life, and safety of batteries to deteriorate. We tested cells containing five positive electrode chemistries, LFP (olivine structure), LMO (spinel), LCO (layered), NMC811 (layered) and NCA (layered), using fast-charging protocols. After testing, the negative electrodes from cells containing positive electrodes crystallizing with a layered structure were found to have more lithium deposited on their surfaces. Further, those crystallizing with a layered structure also tended to have a larger increase in impedance than those crystallizing with a spinel or olivine structure. Characterization of the negative electrodes by X-ray photoelectron spectroscopy showed that using the concentrations of LiF and Li x PO y F z as metrics, the concentration of LiF in the SEI from the cell with different positive electrodes is LFP > LMO > LCO ~ NMC811 > NCA; and for Li x PO y F z , the order is LMO > LFP > NCA > NMC811 > LCO. Clearly, the positive-electrode material was influencing the amounts of these materials formed.

25 ENERGY STORAGE↗

DOE OSTI2022

Lattice Optimization for Porous Electrode

This code performs an optimization over the structure of a porous electrode formed from a lattice of unit cells. This is a steepest descent version of the code used in: V. A. Beck, J. J. Wong, C. F. Jekel, D. A. Tortorelli, S. E. Baker, E. B. Duoss and M. A. Worsley, Computational design of microarchitected porous electrodes for redox flow batteries, J. Power Sources, 2021, 512, 230453.

Wong, JonathanJ↗

DOE OSTI2023

Liquid-type room-temperature fluoride ion batteries

The present disclosure relates to fluoride ion batteries and structures of metal based electrode materials for various fluoride ion batteries. The structures of the metal based electrode materials comprise one or more shells or interfaces, enabling the electrodes to operate at room temperature with a liquid electrolyte.

Xu, Qingmin↗

DOE OSTI2024

Simple processing via thermal treatment and catalyst infiltration to enhance nickel electrode performance for liquid alkaline water electrolyzers

Two simple processes for enhancing liquid alkaline water electrolyzer performance are demonstrated. Both enhance 3D Ni electrodes by introducing a micron-scale rough structure throughout the bulk of the electrode. Oxidation/reduction relies on a simple thermal treatment cycle to create surface roughening through the volumetric expansion during NiO formation and volume contraction during reduction back to Ni metal. Catalyst infiltration introduces a washcoat of additional metal particles throughout the electrode, by flooding the electrode with catalyst precursor and converting it to micron-scale particles via a reducing thermal treatment. Further, the largest improvement in performance (211mV at 1.8Acm -2 ) is observed for infiltrated NiFe-3x catalyst. For Fe-free Ni-only electrodes, oxidation/reduction provides a larger improvement (157 mV at 1.8Acm -2 ) than infiltrated Ni-3X (106mV at 1.8Acm -2 ). For both processes, the observed electrode surface structure and performance is quite sensitive to the thermal treatment temperature.

08 HYDROGEN↗

DOE OSTI2022

Less can be more: Insights on the role of electrode microstructure in redox flow batteries from two-dimensional direct numerical simulations

Understanding how to structure a porous electrode to facilitate fluid, mass, and charge transport is key to enhancing the performance of electrochemical devices, such as fuel cells, electrolyzers, and redox flow batteries (RFBs). Here, using a parallel computational framework, direct numerical simulations are carried out on idealized porous electrode microstructures for RFBs. Strategies to improve an electrode design starting from a regular lattice are explored. By introducing vacancies in the ordered arrangement, it is possible to achieve higher voltage efficiency at a given current density, thanks to improved mixing of reactive species, despite reducing the total reactive surface. Careful engineering of the location of vacancies, resulting in a density gradient, outperforms disordered configurations. Our simulation framework is a new tool to explore transport phenomena in RFBs, and our findings suggest new ways to design performant electrodes.

25 ENERGY STORAGE↗

DOE OSTI2020

Evaporation-Induced Vertical Alignment Enabling Directional Ion Transport in a 2D-Nanosheet-Based Battery Electrode

2D nanosheets have been widely explored as electrode materials owing to their extraordinarily high electrochemical activity and fast solid-state diffusion. However, the scalable electrode fabrication based on this type of material usually suffers from severe performance losses due to restricted ion-transport kinetics in a large thickness. Here, a novel strategy based on evaporation-induced assembly to enable directional ion transport via forming vertically aligned nanosheets is reported. The orientational ordering is achieved by a rapid evaporation of mixed solvents during the electrode fabrication process. Compared with conventional drop-cast electrodes, which exhibit a random arrangement of the nanosheets and obvious decrease of rate performance with increasing thickness, the electrode based on the vertically aligned nanosheets is able to retain the original high rate capability even at high mass loadings and electrode thickness. Furthermore, combined electrochemical and structural characterization reveals the electrode composed of orientation-controlled nanosheets to possess lower charge-transfer resistances, leading to more complete phase transformation in the active material.

25 ENERGY STORAGE↗

DOE OSTI2025

Effect of Electro-Sprayed Porous Electrodes on the Performance and Stability of Water Electrolysis

The efficiency of proton exchange membrane water electrolysis (PEMWE) is a critical issue in realizing the production of green hydrogen. Here, the coexistence of three phases in the catalyst layer of PEMWE causes the mass transport limitation at the interfaces between them. In particular, the vigorous production of gaseous hydrogen and oxygen derived from liquid water is generated in the form of bubbles that seriously deactivate the membrane-electrode assembly (MEA). In this study, we investigated the effect of porous structure in the electrode on the efficiency of hydrogen production at high current density, which is highly related to the mass transport limitation. A widely used commercial catalyst (IrO 2 ) were directly coated on the membrane by the electro-spray method. The porous electrodes on the membrane were formed by the charged catalyst particles that repulsed each other due to the electrostatic forces of the particles. Our membrane electrode assembly (MEA) exhibited outstanding electrolysis performances such as 5.3 A cm -2 and 3.2 A cm -2 at 2.0 V and 1.8 V, respectively, which are the highest values compared with the results published in the current studies. In addition to the porosity, it was confirmed that optimum binder contents positively affect the hydrophobicity and contact resistance of MEA. Through a simple porosity-controlled technique, the performance of PEMWE, in which three phases coexist, can be improved by more than 60 %. Accordingly, we expect that our systematic study on the role of porosity in the electrodes opens a new era to efficiently produce green hydrogen.

catalysts↗

DOE OSTI2023

Hierarchically structured MoO2/dopamine-derived carbon spheres as intercalation electrodes for lithium-ion batteries

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99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2022

Magnetite (Fe 3 O 4 )—multiwalled carbon nanotube composite structures with performance as high rate electrode materials for Li-ion batteries

A method of synthesizing an electrode material for lithium ion batteries from Fe 3 O 4 nanoparticles and multiwalled carbon nanotubes (MWNTs) to yield (Fe 3 O 4 -NWNTs) composite heterostructures. The method includes linking the Fe 3 O 4 nanoparticles and multiwalled carbon nanotubes using a π-π interaction synthesis process to yield the composite heterostructure electrode material. Since Fe 3 O 4 has an intermediate voltage, it can be considered an anode (when paired with a higher voltage material) or a cathode (when paired with a lower voltage material).

Wong, Stanislaus↗

DOE OSTI2021

A universal method to fabricating porous carbon for Li-O 2 battery

The main bottleneck in the application of biomass-based carbon material in energy field is the development of an economical, nanoscale controllable and universal fabrication method. Herein, we demonstrate that a biomass-derived carbon consisting of loose carbon nanosphere clusters could serve as an ideal cathode material for high performance Li-O 2 batteries. The carbon nanomaterial can be prepared from both biomass derivatives and crude biomass by a low cost, facile and nanoscale controllable method. The open slit-shaped hierarchical pore structure endows the electrode sufficient active surface sites and mass transport channels that are not easily asphyxiated by the discharge products. The concentration of oxygenic groups and structure defects on the surface of obtained carbon materials is very low, which minimizes the side reactions associated with carbon decomposition. Finally, the unique pore structure and surface properties of the carbon electrode give rise to a superhigh specific capacity of 20,300 mA h g -1 and an extremely long cycle life which a cyclic capacity retention of 100% is maintained for 543 cycles with current density of 0.2 mA cm -2 at controlled discharge-charge depths of 500 mA h g -1 .

25 ENERGY STORAGE↗

DOE OSTI2023

Proton-Conducting Solid Oxide Electrolysis Cells for Large-scale Hydrogen Production at Intermediate Temperatures

Proton-conducting electrolyte based SOECs offer potential for operation at low to intermediate temperatures. Although yttrium-doped barium zirconate (BZY) and ceria-doped barium zirconate (BCY) have conductivity of 0.01 and 0.017 S.cm -1 respectively at 650C in comparison to the conductivity of 0.015 S.cm -1 for 8-YSZ at 850°C, there remains technology gaps and research needs related to understanding of chemical and structural stability in oxidizing and/or reducing atmospheres at intermediate temperatures, material processing and densification techniques, high polarization losses, and electrode poisoning due to intrinsic and extrinsic gas phase contaminants. Synthesis methods have produced proton-conducting materials and cells that met degradation rate targets, showcasing stable hydrogen production. Improved performance was evident in the HSOEC cell, achieving higher hydrogen production at a lower operating temperature compared to standard cells. Collaborations with multiple research facilities ensured scaling up of synthesis processes and milestone achievements for large-scale manufacturing. Assessment of contaminants revealed their adverse effects on electrode performance and structural stability. Contaminants like Cr and Si compounds, in high humidity, degraded electrodes by forming stable silicate and chromates, inhibiting active surface reactions. Getter materials showed promise in capturing contaminants, suggesting potential for mitigation.

08 HYDROGEN↗

DOE OSTI2025

The Sensitivity of Nickel Substitution in the Structural Design of Manganese-Based Layered and Lithiated Spinel Electrodes for Li-Ion Batteries

A concerted effort is being made at Argonne National Laboratory to explore and develop high-performance lithium-manganese-nickel-oxide cathode materials for the lithium battery industry. They are both energy- and cost-competitive relative to cobalt- and nickel-rich systems, such as LiCoO 2 , LiNi 0.8 Co 0.15 Al 0.05 O 2 , and LiNi 0.8 Mn 0.1 Co 0.1 O 2 . The recent discovery of the structural versatility of LiNi 0.5 Mn 0.5 O 2 , has revealed that it can exist in three configurations: lithiated spinel, partially disordered layered, and completely disordered rock salt within a common cubic-close-packed oxygen array. This versatility opens up the possibility of designing structurally integrated electrode components with interlinking 2-D (layered) and 3-D (spinel) channels for Li-ion transport. This paper highlights the sensitivity of Ni substitution and synthesis temperature on the structural and electrochemical properties of LiNi 0.50 Mn 0.50 O 2 , LiNi 0.53 Mn 0.47 O 2 , LiNi 0.47 Mn 0.53 O 2 , and LiNi 0.25 Mn 0.75 O 2 electrodes, as well as a cobalt-containing composition, LiNi 0.333 Mn 0.333 Co 0.333 O 2 , when synthesized at a relatively low temperature of 400 °C.

25 ENERGY STORAGE↗

DOE OSTI2024

Operando Freezing Cryogenic Electron Microscopy of Active Battery Materials

Abstract Understanding structural and chemical evolution of battery materials during operation is critical to achieving safe, efficient, and long-lasting energy storage. Cryogenic electron microscopy (cryo-EM) has become a valuable tool in battery characterization, leveraging low temperatures to improve stability of sensitive materials under electron beam irradiation. However, typical cryo-EM sample preparations leave extended time between the electrochemical point of interest and ex situ freezing of samples, during which active structures may relax, degrade, or otherwise evolve. Here, we detail a method for operando freezing cryo-EM to preserve and characterize native electrode and interfacial structures that arise during battery cycling, based on an operando plunge freezer and cold sample removal process. We validate the method on multiple electrode materials and quantify and discuss the freezing rate achieved. Operando freezing cryo-EM can be used to directly visualize transient features that arise at active electrochemical interfaces, to enable deeper understanding of structural evolution and interfacial chemistry in batteries and other electrochemical systems.

25 ENERGY STORAGE↗

DOE OSTI2023

Prospective Application, Mechanism, and Deficiency of Lithium Bis(oxalate)Borate as the Electrolyte Additive for Lithium-Batteries

Lithium bis(oxalate)borate (LiBOB) is one of the most common film-forming electrolyte additives used in lithium ion batteries (LIBs), since it can form a dense boron-containing polymer as a solid electrolyte interlayer (or cathode electrolyte interlayer) in order to isolate the electrode material from the electrolyte and prevent side reactions. LiBOB can serve as HF scavenger to maintain the structural integrity of electrodes via avoiding the transition metal dissolution caused by HF attack. Additionally, LiBOB also can react with LiPF 6 to generate lithium difluoro (oxalate)borate (LiDFOB) that can be further used as a clean-up agent for reactive oxygen radicals. This article lists the application of LiBOB in high capacity and high voltage cathode materials, and also reviews the working mechanisms of LiBOB used in these materials to improve the performance of LIBs. Finally, it presents the current shortcomings of LiBOB and strategies to overcome these. This article is expected to provide useful insights for employing LiBOB as a feasible method of dealing with the difficulty of running high capacity LIBs stably under high voltage.

25 ENERGY STORAGE↗