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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Molten fluid electrode apparatus

A battery includes negative electrode material and positive electrode material where the materials are in a solid phase except for selected portions that are heated to transform the selected portions into a fluid. The fluid portion of negative electrode material is directed to a negative electrode region of a reaction chamber and the fluid portion of positive electrode material is directed to a positive electrode region of the reaction chamber where a solid electrolyte containing ions of the negative electrode separates the positive electrode region from the negative electrode region.

Vissers, Daniel R.↗
DOE OSTI2022

Multi-electrode/multi-modal atmospheric pressure glow discharge plasma ionization device

Apparatus include an atmospheric pressure glow discharge (APGD) analyte electrode defining an analyte discharge axis into an APGD volume, and a plurality of APGD counter electrodes having respective electrical discharge ends directed to the APGD volume, wherein the APGD analyte electrode and the APGD counter electrodes are configured to produce an APGD plasma in the APGD volume with a voltage difference between the APGD analyte electrode and one or more of the AGPD counter electrodes. An electrode can be integrated into an ion inlet. Apparatus can be configured to perform auto-ignition and/or provide multi-modal operation through selectively powering electrodes. Electrode holder devices are disclosed. Related methods are disclosed.

Koppenaal, David W.↗
DOE OSTI2022

Open electrodes for in-plane field generation

An electrode film includes a first electrode pattern having a first set of parallel conductive electrodes and a second electrode pattern having a second set of parallel conductive electrodes disposed on a surface of a transparent film. The conductive electrodes in the first and second electrode patterns are conductive mesh patterns including a pattern of open areas and are arranged in an interlaced pattern. The first and second electrode patterns are configured to be connected to respective sources of electrical power supplying respective waveforms to generate a time-varying electric field pattern above a surface of the electrode film.

42 ENGINEERING↗
DOE OSTI2025

Implementing hydrogen oxidation reaction on Pt for controlling counter electrode processes

The search for active, stable, and durable materials for electrochemical energy technologies requires increasing levels of precision to establish true structure-function relationships and guide materials design from atomic and molecular scale. This increases the level of control required over the experimental system for proper materials evaluation. The choice of counter electrode material become crucial, as Pt dissolution at high voltages may cause contamination to the working electrode, especially when studying reductive processes in reactions such as oxygen reduction reaction (ORR), H 2 evolution reaction (HER), and the CO 2 reduction reaction. The learnings from “old school” electrochemistry groups lead us to leverage H 2 reactions over Pt to construct a counter electrode system with controlled potential that eliminates Pt ion contamination concerns. In here we discuss the construction of such Pt|H 2 counter electrode where key experimental aspects such as the H 2 flow rate and effective distribution determines the maximum current this counter electrode can accommodate before switching to high voltage and triggering Pt dissolution. Lastly, we demonstrate the use of the Pt|H 2 counter electrode in aqueous electrolytes during HER occurring on the working electrode at varying currents, showing that the Pt content in the cell remains below parts per trillion (ppt) up to 10 mA, and below 50 ppt at 100 mA up to 1 h of constant current hold. This work provides a guide to the implementation of Pt|H 2 counter electrodes to improve the precision of electrochemical experiments in search of highly active, selective, and durable materials for energy technologies.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Rare Earth Nickelate Electrodes Containing Heavily Doped Ceria for Reversible Solid Oxide Fuel Cells

The electrochemical performance of composite rare-earth nickelate-rare-earth doped ceria oxygen electrodes, with a high level of rare-earth doping in ceria are reported. Additionally, the chemical stability of these compositions is reported at both the sintering (1240 ?C) and operating temperature (800 ?C). Specifically, a lanthanum nickelate La2NiO4+d (LNO) ?? 50 mol% lanthanum doped ceria (LDC50) oxygen electrode and a neodymium nickelate Nd2NiO4+d (NNO) ?? 50 mol% neodymium doped ceria (NDC50) oxygen electrode are tested in solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes and compared to a composite (La0.75Sr0.25)0.95MnO3±d (LSM)-8 mol% yttria stabilized zirconia (YSZ) electrode. The LNO–LDC50 oxygen electrode reaches a current density which is approximately three times that of the LSM-YSZ electrode in SOFC mode at 0.7 V and approximately two times the LSM-YSZ electrode at 1.2 V in SOEC mode. Similarly the NNONDC50 oxygen electrode reaches a current density which is approximately two times and approximately one and a half times that of LSM-YSZ at 0.7 V and 1.2 V respectively. Oxygen surface exchange results for LNO and NNO are also reported which show different oxygen exchange kinetics during oxidation versus reduction steps.

solid oxide electrolysis, solid oxide fuel cell (S↗
DOE OSTI2024

Four-Terminal Electrochemistry: A Back-Gate Controls the Electrochemical Potential of a 2D Working Electrode

We demonstrate that ultrathin semiconductor working electrodes integrated into metal–insulator–semiconductor (MIS) stacks are an enabling platform for understanding non-Faradaic semiconductor electrochemistry. Furthermore, 5 nm thick ZnO electrodes were deposited on 30 nm HfO 2 dielectric on a Pd “gate” electrode. Application of a bias V G between the Pd gate and the ZnO electrode causes electrons to accumulate in the ZnO layer as measured by recording the in-plane sheet conductance. By contacting the top surface of the ZnO layer with the electrolyte in a conventional three-electrode electrochemical cell, we show that the gate voltage V G modulates the electrochemical potential V ZnO of the ZnO film with respect to a reference electrode. Electrochemical potential changes ΔV ZnO up to –1 V vs Ag/Ag + are achieved for V G = +7 V. Furthermore, by measuring V ZnO vs V G , we extract the quantum capacitance CQ of the ZnO film as a function of the Fermi-level position, which provides a direct measure of the ZnO electronic density of states (DOS). Finally, we demonstrate that the gated ZnO working electrodes can disentangle the two principal components of electrochemical potential, namely, the Fermi-level shift Δδ and the double-layer charging energy eΔΦ EDL . This disentanglement hinges on a fundamental difference between back-gating and normal electrochemical control, namely, that electrochemical control requires double-layer charging, while back-gate control does not. Collectively, the results show that the backside gate electrode is an effective fourth terminal that enables measurements that are difficult to achieve in conventional three-terminal electrochemical setups.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Lithium Plating Characteristics in High Areal Capacity Li-Ion Battery Electrodes

Li-ion battery degradation and safety events are often attributed to undesirable metallic lithium plating. Since their release, Li-ion battery electrodes have been made progressively thicker to provide a higher energy density. However, the propensity for plating in these thicker pairings is not well understood. Herein, we combine an experimental plating-prone condition with robust mesoscale modeling to examine electrode pairings with capacities ranging from 2.5 to 6 mAh/cm 2 and negative to positive (N/P) electrode areal capacity ratio from 0.9 to 1.8 without the need for extensive aging tests. Using both experimentation and a mesoscale model, we identify a shift from conventional high state-of-charge (SOC) type plating to high overpotential (OP) type plating as electrode thickness increases. Further, these two plating modes have distinct morphologies, identified by optical microscopy and electrochemical signatures. We demonstrate that under operating conditions where these plating modes converge, a high propensity of plating exists, revealing the importance of predicting and avoiding this overlap for a given electrode pairing. Further, we identify that thicker electrodes, beyond a capacity of 3 mAh/cm 2 or thickness >75 μm, are prone to high OP, limiting negative electrode (NE) utilization and preventing cross-sectional oversizing the NE from mitigating plating. Here, it simply contributes to added mass and volume. The experimental thermal gradient and mesoscale model either combined or independently provide techniques capable of probing performance and safety implications of mild changes to electrode design features.

25 ENERGY STORAGE↗
DOE OSTI2021

Localized strain profile in surface electrode array for programmable composite multiferroic devices

In this work, we investigate localized in-plane strains on the microscale, induced by arrays of biased surface electrodes patterned on piezoelectrics. Particular focus is given to the influence that adjacent electrode pairs have on one another to study the impact of densely packed electrode arrays. We present a series of X-ray microdiffraction studies to reveal the spatially resolved micrometer-scale strain distribution. The strain maps with micrometer-scale resolution highlight how the local strain profile in square regions up to 250 x 250 lm 2 in size is affected by the surface electrodes that are patterned on ferroelectric single-crystal [Pb(Mg 1/3 Nb 2/3 )O 3 ] x -[PbTiO 3 ] 1-x . The experimental measurements and simulation results show the influence of electrode pair distance, positioning of the electrode pair, including the angle of placement, and neighboring electrode pair arrangements on the strength and direction of the regional strain. Our findings are relevant to the development of microarchitected strain-mediated multiferroic devices. The electrode arrays could provide array-addressable localized strain control for applications including straintronic memory, probabilistic computing platforms, microwave devices, and magnetic-activated cell sorting platforms.

42 ENGINEERING↗
DOE OSTI2022

Effect of electrochemical cycling on microstructures of nanocomposite silicon electrodes using hyperpolarized 129 Xe and 7 Li NMR spectroscopy

The microstructural stability of composite electrodes during electrochemical cycling is critically important as it dictates the performance of Li-ion batteries. The issue becomes even more important for the high capacity alloying anode such as silicon that typically exhibits dramatic lithiation–delithiation-induced volume changes. The solid electrolyte interphase (SEI) layer formed on the active electrode surface has a profound effect on the overall microstructural stability of composite electrodes. An ideal SEI layer allows Li+ ions in and out of the electrode, but is an insulator to electrons, preventing the electrolyte from being further reduced. However, the SEI layers formed during initial lithiation may experience changes or degradation with subsequent cycling, adversely affecting the electrode performance. A combination of hyperpolarized 129 Xe and 7 Li nuclear magnetic resonance spectroscopies was applied to probe the microstructures of nanocomposite silicon electrodes at various stages of the lithiation–delithiation cycle. The results obtained from this study shed light on the degradation mechanism of nanocomposite Si electrodes upon electrochemical cycling and should prove useful in the effort to design more robust electrodes in the future.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Quantifying Negative Effects of Carbon-Binder Networks from Electrochemical Performance of Porous Li-Ion Electrodes

Porous Li-ion electrodes contain active particles, ion transporting electrolyte, and carbon-binder networks. While macrohomogeneous models are often used to predict electrode behavior, accurate predictions remain challenging, owing to the incomplete understanding of the critical role of carbon-binder networks and how they affect the electrochemical response. The present study systematically characterizes these effects in terms of effective properties by utilizing macrohomogeneous models to analyze the measured responses for electrodes with different carbon-binder content, electrode thickness, and porosity but with identical materials. We find that the impact of the carbon-binder network is more severe than previously thought. Even for low carbon-binder content (5 %wt. dry electrode), the presence of the network decreases the reaction area and increases the ion transport resistance, negatively impacting electrode performance. These effects scale with not just porosity or active material volume but also with carbon-binder content. The findings underscore the importance of connecting all effective properties to electrode specifications in a full factorial sense to transform the electrode design paradigm.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Manufacturing of Fabric Electrodes using a High-Throughput Screening Platform for Redox Flow Batteries

The objective of this project is to establish a new manufacturing methodology with machine learning- based high-throughput screening for the design and development of hierarchical structured, high-performance fabric electrodes for redox flow batteries (RFBs). The end goal of the project is to design and manufacture fabric electrodes for RFB applications that can provide 250 mA/cm2 current density operation for 100-cycles with 80% average energy efficiency. This was accomplished by first examining the structure-performance-property linkages of the electrodes provided by our partner, AvCarb. The electrodes’ microstructure was characterized by determining their pore size distribution, tortuosity, specific surface area, and porosity. The ohmic, charge transfer and mass transfer resistances were then calculated using electrochemical impedance spectroscopy. Carbon cloth electrodes showed the greatest resistance, which was dominated by charge transfer resistance, which we believe is related to the surface functionalization. Full cell cycling was used in order to determine the area specific resistance and energy efficiency of the cells. All of this experimental data and the results of the mathematical model (to increase the amount of inputs with parametric sweeping) were used to develop a machine learning-based model for the design of high-performance fabric electrodes. Using the results from the machine learning tool, optimized electrodes were fabricated by AvCarb. The ohmic, charge transfer and mass transfer resistances for these new electrodes were measured, and both performed better than any of the initial samples which had been provided by AvCarb.

25 ENERGY STORAGE↗
DOE OSTI2025

Kinetics Measurements in Resistive Electrolytes Using Ring-Disk Electrode: Ring as Current “Shield” Enables Uniform Disk Current Distribution

Rotating disk electrodes are commonly used for electrochemical kinetics measurements. A major disadvantage of these types of electrodes is their nonuniform secondary current distribution, especially when performing electroanalytical measurements in resistive electrolytes. Such nonuniform current distribution can render the values of kinetics constants extracted from the disk electrode to be highly inaccurate. Furthermore, one emerging class of electrolytes that suffer from low ionic conductivities is deep eutectic solvents (DES). DES are a promising class of electrolytes for various emerging applications; however, due to their resistive nature, the secondary current distribution when using them is typically highly nonuniform. For example, the Wagner number when measuring Cu²⁺/Cu⁺ kinetics in choline chloride–ethylene glycol DES (1:4 molar ratio of ChCl:EG) is very low (<0.1), indicating highly nonuniform current distribution over the disk electrode. We show here that the Cu²⁺/Cu⁺ exchange current density measured using disk electrodes is very inaccurate due to the aforementioned nonuniform current distribution. To obtain uniform disk current distribution, we employ here a coplanar concentric rotating ring-disk electrode (RRDE), where the ring serves the function of a current “shield.” Specifically, we show using modeling that the ring minimizes the current distribution nonuniformity at the disk by effectively shielding the disk against current spikes near the disk edge. This enables improved precision in electrode kinetics measurements for the Cu²⁺/Cu⁺ couple in resistive DES. To enable broad applicability of this technique, an analytical expression based on the Wagner number is integrated into an iterative algorithm to help users identify ring conditions to achieve uniform current distribution and thus improved electroanalytics at the disk.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Dramatic effect of electrode type on tunnel junction based molecular spintronic devices

A new class of molecular spintronic devices can be fabricated by chemically bonding magnetic molecular channels to the electrodes of a prefabricated tunnel junction with exposed side edges. Prior experimental studies showed that the cyanide-bridged octametallic molecular cluster, [(pzTp)FeIII(CN)3]4[NiII(L)]4¬[O3SCF3]4 [(pzTp) = tetra(pyrazol-1-yl)borate; L = 1-S(acetyl)tris(pyrazolyl)decane] molecule impact depended on the type of metallic electrodes used in the tunnel junction testbed. Experimental magnetization and transport studies showed a dramatic difference in molecule response on tunnel junctions with different combinations of metallic electrodes. Transport via paramagnetic molecular channels on a tunnel junction involving paramagnetic and ferromagnetic metal electrodes was dramatically different than the suppressed current state observed on tunnel junctions involving two ferromagnetic electrodes. We conducted theoretical studies to understand the experimental data and explore a wide range of electrode materials on tunnel junction-based molecular spintronics devices (TJMSD). Here, we report a Monte Carlo simulation study that focuses on understanding the effect of electrodes on the magnetic and physical properties of TJMSD. A 3D Heisenberg model of cross-junction-shaped TJMSD was used for the simulation study. We studied the effects of ferromagnetic, paramagnetic, and antiferromagnetic electrode materials. This study provides insights for designing and understanding futuristic molecular spintronics devices.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Removal and recovery of ammonia from simulated wastewater using Ti3C2Tx MXene in flow electrode capacitive deionization

Abstract Flowing electrode capacitive deionization systems (FE-CDI) have recently garnered attention because of their ability to prevent cross contamination and operate in uninterrupted cycles ad infinitum. Typically, FE-CDI electrodes suffer from low conductivity, reducing deionization performance. Utilization of higher mass loadings to combat this leads to poor rheological properties. Herein, Ti 3 C 2 T x MXene was introduced as 1 mg mL −1 slurry electrodes in an FE-CDI system for the removal and recovery of ammonia from simulated agricultural wastewater. The electrode performance was evaluated by operating the FE-CDI system with a feed solution of 500 mg L −1 NH 4 Cl running in batch mode at a constant voltage of 1.20 and −1.20 V in charging and discharging modes, respectively. Despite the low loading, Ti 3 C 2 T x flowing electrodes showed markedly improved performance, achieving 60% ion removal efficiency in a saturation time of 115 min with an adsorption capacity of 460 mg g −1 . To understand the high adsorption performance of the electrodes, physiochemical and structural analysis was done via a variety of characterization techniques such as SEM, TEM, XRD, DLS, and Raman spectroscopy. Cyclic voltammetry and galvanostatic charge/discharge profiles were obtained to evaluate the electrochemical properties of the electrodes. The system proved to be an energy-saving technology by exhibiting a charge efficiency of 58–70% while operating at an energy consumption of 0.45 kWh kg −1 . A 92% regeneration efficiency showed that the electrodes were stable and suitable for long term and scalable usage. The results demonstrate that MXenes have the potential to improve the FE-CDI process for energy-efficient removal and recovery of ammonia.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Promotion of oxygen reduction reaction on a double perovskite electrode by a water-induced surface modification

Highly efficient air electrodes are a key component of reversible fuel cells for energy storage and conversion; however, the development of efficient electrodes that are stable against water vapor remains a grand challenge. Here we report an air–electrode, composed of double perovskite material PrBa 0.8 Ca 0.2 Co 2 O 5+δ (PBCC) backbone coated with nanoparticles (NPs) of BaCoO 3-δ (BCO), that exhibits remarkable electrocatalytic activity for oxygen reduction reaction (ORR) while maintaining excellent tolerance to water vapor. When tested in a symmetrical cell exposed to wet air with 3 vol% H 2 O at 750 °C, the electrode shows an area specific resistance of ~0.03 Ω cm 2 in an extended period of time. The performance enhancement is attributed mainly to the electrocatalytic activity of the BCO NPs dispersed on the surface of the porous PBCC electrode. Moreover, in situ Raman spectroscopy is used to probe reaction intermediates (e.g., oxygen species) on electrode surfaces, as the electrochemical properties of the electrodes are characterized under the same conditions. The direct correlation between surface chemistry and electrochemical behavior of an electrode is vital to gaining insight into the mechanisms of the electrocatalytic processes in fuel cells and electrolysers.

25 ENERGY STORAGE↗
DOE OSTI2020

Preferential Stripping of a Lithium Protrusion Resulting in Recovery of a Planar Electrode

Lithium metal is a high-energy-density battery electrode material, but the largely irreversible growth of lithium protrusions on an initially planar electrode during cycling makes it unsuitable for incorporation into a commercial battery. In this study, a lithium electrode with globular protrusions was stripped electrochemically, and the local morphology of the electrode as a function of time was determined by hard X-ray tomography. We demonstrate that globules are preferentially stripped compared to a planar electrode in our system, which incorporates a nanostructured block copolymer electrolyte. We report current density at the electrode as a function of micron-scale position and time. The local current density during the electrode healing process calculated from a reference frame at the electrode/electrolyte interface provides insight into the driving forces responsible for selective stripping of the globule. These results imply the possibility of discharging protocols that may return a lithium electrode to its initial planar state.

Maslyn, Jacqueline A. (ORCID:0000000264812070)↗
DOE OSTI2022

Numerical Simulation and Modeling of Hydrogen Gas Evolution on Planar and Microwire Array Electrodes

The impact of gas evolution on the electrochemical characteristics of planar electrodes and microwire array electrodes has been analyzed using modeling and simulation. The impacts can mainly be broken into three phenomena: a) a shift in the local reversible hydrogen electrode potential; b) hyperpolarization; and c) an increase in the solution resistance of the electrolyte. The local reversible hydrogen electrode potential shift was found to play the most important role, constituting >40% of the total potential drop between the cathode and reference electrode, following correction for cell resistance. Compared to planar electrodes, a microwire array structure reduces the impact of bubbles on the solution conductance, but the shift in the local reversible hydrogen electrode potential varies with distance from the actual electrode surface.

25 ENERGY STORAGE↗
DOE OSTI2026

Low-Temperature Plasma-Based Metrology of Lithium-Ion Battery Electrode Materials (CRADA Final Report)

As part of the Cyclotron Road program, SirenOpt Inc. evaluated its low-temperature plasma-based metrology sensor prototype for measuring multiple critical properties of lithium-ion battery electrode materials in parallel and in real-time. Cost-effective, minimal-waste manufacturing of high-performance battery electrode materials will be vital for achieving society’s net-zero carbon emission goals. Because existing electrode metrology sensors cannot operate within most sections of manufacturing lines, manufacturers often complete hundreds of processing steps before they can test their products and detect problems. When manufacturers perform these offline tests, they typically only test a small portion of the manufactured products. Current electrode manufacturing thus often yields many low-quality products, or off-spec products that must be thrown away all together. For example, at least 6% of the total lithium-ion battery manufacturing cost (i.e., over $250 million/year for the average gigafactory) is devoted to processing defective electrodes that are not scrapped until performance tests are failed during late-stage quality control checks. Electrode variability also leads manufacturers to build extra cells into battery packs to reduce the risk of poor performance. For example, many electric vehicle (EV) manufacturers include up to 10% more cells than needed, which substantially increases the cost and weight of the final EV product. The SirenOpt sensor can potentially enable early detection of poorly manufactured electrodes and allow them to be removed earlier from manufacturing lines, which can save battery manufacturers (hundreds of) millions of dollars per year. The sensor can further be used to improve product quality by accelerating R&D and process optimization, improving quality control, and enabling real-time process control. Overall, a real-time, in-situ metrology strategy can create unprecedented opportunities for implementation of smart manufacturing practices and advanced quality and process control solutions to realize higher battery electrode throughput and performance.

25 ENERGY STORAGE↗