Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “composite electrode”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Enabling electrochemical N 2 reduction to NH 3 in the low overpotential region using non-noble metal Bi electrodes via surface composition modification

The electrochemical N 2 reduction reaction (ENRR) that can produce NH 3 using water as the hydrogen source at ambient temperature and pressure can be an exciting alternative to the Haber–Bosch process. The major challenge for electrochemical NH 3 production is the competing hydrogen evolution reaction (HER), which seriously limits the faradaic efficiency (FE) for NH 3 production. To date, noble metal electrocatalysts that are inactive for the HER have mainly been investigated for the ENRR. Studies reporting a FE greater than 10% for NH 3 production using non-noble metal catalysts in the low overpotential region (E ≤ 0.2 V vs. RHE) are very rare. This study reports effective electrochemical surface modification strategies that drastically increase the ENRR activity of a non-noble Bi electrode in the low overpotential region and achieve a FE for NH 3 production as high as 13.2% at -0.2 V vs. RHE in pH 7.5 phosphate buffer. Finally, the effect of each of the surface modifications on the activity for the ENRR and the electrode stability during the ENRR were systematically elucidated, which may be used to develop general strategies to enhance the ENRR activities of other non-noble metal electrodes in the low overpotential region.

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

Thin Film Electrodes for Anodic Stripping Voltammetry: A Mini-Review

Anodic stripping voltammetry (ASV) is a powerful electrochemical analytical technique that allows for the detection and quantification of a variety of metal ion species at very low concentrations in aqueous media. While early, traditional ASV measurements relied on macroscopic electrodes like Hg drop electrodes to provide surfaces suitable for plating/stripping, more recent work on the technique has replaced these electrodes with thin film metal electrodes generated in situ . Such electrodes are plated alongside the analyte species onto the surface of a primary electrode, producing a composite metal electrode from which the analyte(s) can then be stripped, identified, and quantified. In this minireview, we will explore the development and use of these unique electrodes in a variety of different applications. A number of metals (e.g., Hg, Bi, Sn, etc.) have shown promise as thin film ASV electrodes in both acidic and alkaline media, and frequently multiple metals in addition to the analyte of interest are deposited together to optimize the plating/stripping behavior, improving sensitivity. Due to the relatively simple nature of the measurement and its suitability for a wide range of pH, it has been used broadly: To measure toxic metals in the environment, characterize battery materials, and enable biological assays, among other applications. We will discuss these applications in greater detail, as well as provide perspective on future development and uses of these thin film electrodes in ASV measurements.

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

Technoeconomic Analysis of Dye Sensitized Solar Cells (DSSCs) with WS 2 /Carbon Composite as Counter Electrode Material

Exploration of clean and renewable energy materials is necessary due to the coming energy crisis and environmental problems. Solar energy is one of the favorable energy sources because of the continuous energy reservoir and its affluence. Silicon-based solar devices are expensive due to their complicated production process, which limits this technology for urban and other commercial applications. Among the third generation of solar cells, Dye-Sensitized Solar Cells (DSSCs) have attracted widespread attention as potential cost-effective alternatives to silicon-based solar cells. In this paper, the commercializing potential of the DSSCs is investigated. A module is introduced where the materials, equipment, and distribution of direct manufacturing costs are calculated. The manufacturing costs and the Levelized Cost of Energy (LCOE) of these DSSCs for a system lifetime of 25 years were determined to be USD 22.40 per m 2 and USD 0.0438 per kWh and the module price of this technology is USD 0.18 per W and the total installed system cost is USD 0.88 per W in Kansas which suggest that this PV technology could challenge other leading PV technologies.

14 SOLAR ENERGY↗
NASA NTRS1993

(abstract) Effect of Electrolyte Composition on Carbon Electrode Performance

Rechargeable lithium cells containing lithium foil anodes are reported to have limited cycle life (at 100% DOD) performance and safety problems. These limitations are understood to be due to the high reactivity of elemental Li with the electrolyte and the formation of high surface area Li during cycling. To mitigate these problems, several lithium alloys and lithium intercalation compounds are being investigated as alternate lithium anode materials. Li(sub x)C has been identified as a promising lithium anode material due to its low equivalent weight, low voltage vs. Li, and improved stability towards various electrolytes. In this paper, we report the results of our studies on the electrolyte evaluation for the Li(sub x)C anode.

lithium carbon electrode electrolyte rechargeable ↗
DOE OSTI2021

Carbon material supported hollow metal oxide nanoparticles, methods and applications

A method for preparing a material composition comprising a hollow transition metal oxide nanoparticle supported upon a carbon material support includes a solution impregnation process step, followed by a thermal reduction process step and finally a thermal oxidation process step. The material composition, an electrode and an electrical component such as but not limited to a battery are all predicated at least in-part upon the material composition prepared in accord with the foregoing method. The foregoing material composition, electrode, battery and method may ultimately provide a LIB with enhanced performance.

Yu, Yingchao↗
DOE OSTI2020

Utilizing ink composition to tune bulk-electrode gas transport, performance, and operational robustness for a Fe-N-C catalyst in polymer electrolyte fuel cell

With lower site density and turnover frequency, platinum group metal (PGM)-free catalysts based electrodes are often greater than 50 mu m thick in order to increase performance across the fuel cell operating range. Consequently, PGM-free electrodes have an additional bulk electrode transport resistance beyond the local or aggregate level transport in thin platinum-based electrodes. In parallel to the development of more active and durable PGM-free catalysts, advancements in understanding the interplay between PGM-free electrode fabrication, bulk-electrode transport, proton conductivity and performance are needed. Here, the relationship between ionic and gas phase transport through the electrode thickness is modified by adjusting electrocatalyst and ionomer flocculation/interaction at the ink level. The influence of the ink composition (water/n-propanol content) is examined via various in-situ electrochemical and ex-situ characterization techniques and the resulting electrode structure/performance relationship contrasted with electrode performance robustness across a range of relative humidity (RH). For the electrocatalyst examined here, a water-rich (82 wt% H2O) ink formulation was favorable for operation at high RH due to improved molecular diffusion through larger electrode pores. In contrast, the improved interactions between ionomer and electrocatalyst enabled a more robust electrode and higher performance during low RH operation for the 50 wt% H2O content ink.

08 HYDROGEN↗
DOE OSTI2026

Binder-Stabilized Carbon Fiber Hosts for High-Utilization Sodium–Polysulfide Flow Catholytes

Sodium-sulfur (Na-S) batteries hold promise as high-energy-density batteries for long-duration energy storage due to their high open circuit voltage and Earth-abundant active materials. However, low utilization of the sulfur active material limits the achievable specific capacity, especially when a liquid polysulfide catholyte is utilized. High-surface-area carbon materials demonstrate promise to increase sulfur utilization in a Na-S battery. To make the carbon host material applicable for a flow battery application, a binder is required to bind the carbon materials together and to a porous substrate. Here, we utilize a composite carbon paper electrode coated by polymer,carbon nanofibers (CNFs) and carbon black (CB). By varying the mass ratios of CNF to CB, we found that a 70/20/10 mass ratio of CNF/CB/binder provided the highest capacity (260 mAh g −1 compared to the baseline of 156 mAh g −1 ) and stable battery performance over 100 cycles. Analysis of the composite electrode and full cells reveals that the amount of CB in the composite electrode influences binder distribution, cell resistance, and full cell performance.

Lehmann, Michelle L. [Oak Ridge National Laborator↗
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 OSTI2023

Carbon Electrode with Sputtered Au Coating for Efficient and Stable Perovskite Solar Cells

Halide perovskite solar cells (PSCs) represent a low-cost and high-efficiency solar technology. However, most of the highly efficient PSCs need a noble electrode, such as Au, through thermal evaporation. Here it is reported that a sputtered Au electrode on a PSC could damage the organic hole transport layer (HTL) and the perovskite layer. Here, we report a simple, yet effective sputtered gold nanoparticle decorated carbon electrode to fabricate efficient and stable planar PSCs. The sputtered Au layer on the doctor-bladed coated carbon electrode can be directly applied to the perovskite semicells by mechanical stacking. By optimizing the gold thickness, a power conversion efficiency (PCE) of 16.87% was obtained for the composite electrode-based PSC, while the reference device recorded a PCE of 12.38%. The composite electrode-based device demonstrated 96% performance retention after being stored under humid conditions (50-60%) without encapsulation for ~100 h. This demonstrates a promising pathway toward the commercialization of large-scale manufacturable sputtered electrodes for the PSC solar module.

14 SOLAR ENERGY↗
DOE OSTI2020

Surface-modified cyanide-based transition metal compounds

A system, method, and articles of manufacture for a surface-modified transition metal cyanide coordination compound (TMCCC) composition, an improved electrode including the composition, and a manufacturing method for the composition which may include multiple chelation species (Che_x). The composition, compound, device, and uses thereof according to AxMn(y-k)Mjk[Mnm(CN)(6-p-q)(NC)p(Che_I)rq]z.CHE_GROUP (Vac)(1-z).nH2O, wherein CHE_GROUP includes one or more chelation materials selected from the group consisting of (Che_I)rw, (Che_II)sv, and combinations thereof, and wherein 0 < j≤4, 0≤k≤0.1, 0≤(p+q)≤6, 0 < x≤4, 0 < y≤1, 0 < z≤1, 0 < w≤0.2; −3≤r≤3; 0 < v≤0.2; −3≤s≤3; and 0≤n≤6; wherein x+2(y−k)+jk+(m+(r+1)q−6)z+wr+vs=0.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Surface-modified cyanide-based transition metal compounds

A system, method, and articles of manufacture for a surface-modified transition metal cyanide coordination compound (TMCCC) composition, an improved electrode including the composition, and a manufacturing method for the composition which may include multiple chelation species (Che_x). The composition, compound, device, and uses thereof according to AxMn(y-k)Mjk[Mnm(CN)(6-p-q)(NC)p(Che_I)rq]z. CHE_GROUP (Vac)(1-z).nH2O, wherein CHE_GROUP includes one or more chelation materials selected from the group consisting of (Che_I)rw, (Che_II)sv, and combinations thereof, and wherein 0 < j≤4, 0≤k≤0.1, 0≤(p+q)≤6, 0 < x≤4, 0 < y≤1, 0 < z≤1, 0 < w≤0.2; −3≤r≤3; 0 < v≤0.2; −3≤s≤3; and 0≤n≤6; wherein x+2(y−k)+jk+(m+(r+1)q−6)z+wr+vs=0.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Extreme fast charge aging: Effect of electrode loading and NMC composition on inhomogeneous degradation in graphite bulk and electrode/electrolyte interface

Empowering extreme fast charging (XFC) requires a comprehensive understanding of its application with advanced anode and cathode materials in lithium-ion batteries. No report exists for the full extent of limitations for the anode with crosstalk effect from paired cathode as well as Li plating due to electrode loading under XFC. In this study, a combination of cell testing and multiple length characterization is used to investigate XFC aging mechanism in cells with a low loading of 1.5 mAh cm -2 and high loading of 2.5 mAh cm -2 for graphite (Gr)/Ni-rich LiNi x Mn y Co 1-x-y O 2 (NMCs). Operando XRD mappings show 1.5 mAh cm -2 loadings result in higher strain in graphite for all three cathode types. Among the three NMC cathodes, the graphite from NMC532 and NMC811 cells show comparable strain. Scanning electron microscopy (SEM) images show distinct differences between 6-C-charged anodes in two loadings. Significantly increased electrode thickness can be seen due to more damage in the graphite bulk and accumulation of the electrolyte decomposition products in electrode pores. X-ray photoelectron spectroscopy (XPS) reveals both cathode chemistry and Li plating influence the non-uniform SEI composition on graphite surface. We report higher Ni content in NMC811 promotes the higher levels of salt decomposition on the SEI and formation of higher mass of electrolyte aging products.

25 ENERGY STORAGE↗
DOE OSTI2023

Silver nanowire-indium zinc oxide composite flexible transparent conducting electrodes made by spin-coating and photonic curing

Flexible transparent conducting electrodes (TCE) play a critical role in modern technologies. Eliminating the high-temperature annealing of vacuum- or solution-deposited films will increase production throughput and lower the cost of the final products. Photonic curing uses intense pulses of broadband light to induce material transformations instead of heat. In this work, we combine solution deposition and photonic curing, replacing thermal annealing, to fabricate flexible composite TCE films on plastic polyethylene terephthalate (PET) substrates. The composite TCE films are composed of spin-coated silver nanowire-indium zinc oxide layers. Further, the TCE films’ electrical, optical, and morphological properties are investigated and compared to those of commercially available PET/TCE. A sheet resistance of 15 Ω/sq and an average transmittance from 400 – 700 nm of 77% are achieved with the spin-coated and photonic-cured composite flexible TCE films.

14 SOLAR ENERGY↗
DOE OSTI2022

Silver Nanowire-Indium Zinc Oxide Composite Flexible Transparent Conducting Electrodes Made by Spin- coating and Photonic Curing

Realizing high-throughput, low-cost perovskite solar cell (PSC) manufacturing is highly sought-after in photovoltaic (PV) research in recent years. To fully achieve roll-to-roll (R2R) manufacturing of PSCs, it is important to consider the flexible transparent electrode (TE). PET/ITO is a commonly used substrate for making flexible PSCs. When optimizing transparent conducting materials, there is a tradeoff between sheet resistance (Rsh) and optical transparency. Because commercial PET/ITO substrates are made with slow (~1 m/min) vacuum deposition processes, they tend to be expensive. Therefore, it would be advantageous to develop a high-throughput, R2R compatible, solution-deposition approach for fabricating the TE on PET substrates. While various solution-deposition processes, such as blade coating or slot-die coating, can achieve the desired web speed of > 10 m/min, there is still a need to improve the post-deposition annealing step. One promising post-deposition processing technique is intense-pulsed-light processing, also known as photonic curing. Photonic curing delivers short (0.01 – 100 ms) pulses of broadband (200 – 1500 nm) light from a xenon flash lamp to the samples. Any materials in the sample stack that absorb light will convert the impinging light pulse into heat within the sample, which drives changes in the sample (calcination, phase change, crystallization, etc.). Photonic curing has three main advantages over thermal annealing: 1. Faster processing speed (milliseconds or seconds). 2. Compatibility with plastic substrates. 3. Smaller physical footprint and less wasted energy. Since the light pulses are on for a short time, the intensity can be high while the total energy delivered to the sample is low, minimizing damages to the plastic substrates. In this work, a hybrid TE material is fabricated on PET substrates using photonic curing. The hybrid TE material contains a layer of silver nanowires (AgNWs) and a layer of metal-oxide (InOx, ITO, IZO, etc.). The AgNWs increase the light absorbed by the film during the photonic curing process, which leads to higher processing temperatures, possibly improving the conversion of the metal-oxide layer. The AgNWs also enhance the electrical conductivity of the final TE layer after photonic curing. A AgNW and metal-oxide bilayer is formed by spin coating each solution onto the PET substrate sequentially followed by a single photonic curing process. We use average optical transmittance (Tavg) from 400 to 700 nm and average Rsh to evaluate the TE performance. The following photonic curing parameters are varied to optimize Tavg (maximize) and Rsh (minimize): Pulse voltage, pulse envelope, number of micro-pulses, duty cycle, number of pulses, and pulse repetition rate. Preliminarily, we also observe a significant impact on the TE properties by the volume of AgNW deposited during the spin coating deposition step. Using dispense volumes of 80 µL and 20 µL, we achieve samples with Tavg = 73%, Rsh = 19 Ω/sq, and roughness = 9 nm, and Tavg = 83%, Rsh = 58 Ω/sq, and roughness = 5.6 nm, respectively, after photonic curing.

14 SOLAR ENERGY↗
DOE OSTI2021

Electrolyte compositions for stabilizing silicon electrodes in lithium batteries

A lithium-ion electrochemical cell comprises a first electrode, a second electrode comprising elemental silicon, a microporous separator membrane between the first and second electrodes, and an electrolyte in contact with the electrodes and the membrane. The electrolyte comprises a lithium salt at a concentration in the range of about 0.1 M to about 5 M, and an additional metal salt at a concentration in the range of about 0.001 to about 5 M dissolved in an organic solvent. The additional metal salt comprises a metal cation that can form a lithium-silicon-metal Zintl phase; and the first electrode comprises metallic lithium or a cathode active material capable of donating and accepting lithium ions to and from the second electrode during electrochemical cycling. Electrolytes for use with silicon-containing electrodes also are described.

Vaughey, John T.↗
NASA NTRS2012

An Integrated, Layered-Spinel Composite Cathode for Energy Storage Applications

At low operating temperatures, commercially available electrode materials for lithium-ion batteries do not fully meet the energy and power requirements for NASA fs exploration activities. The composite cathode under development is projected to provide the required energy and power densities at low temperatures and its usage will considerably reduce the overall volume and weight of the battery pack. The newly developed composite electrode material can provide superior electrochemical performance relative to a commercially available lithium cobalt system. One advantage of using a composite cathode is its higher energy density, which can lead to smaller and lighter battery packs. In the current program, different series of layered-spinel composite materials with at least two different systems in an integrated structure were synthesized, and the volumetric and gravimetric energy densities were evaluated. In an integrated network of a composite electrode, the effect of the combined structures is to enhance the capacity and power capabilities of the material to levels greater than what is possible in current state-of-the-art cathode systems. The main objective of the current program is to implement a novel cathode material that meets NASA fs low temperature energy density requirements. An important feature of the composite cathode is that it has at least two components (e.g., layered and spinel) that are structurally integrated. The layered material by itself is electrochemically inactive; however, upon structural integration with a spinel material, the layered material can be electrochemically activated, thereby delivering a large amount of energy with stable cycling. A key aspect of the innovation has been the development of a scalable process to produce submicronand micron-scale particles of these composite materials. An additional advantage of using such a composite electrode material is its low irreversible loss (.5%), which is primarily due to the unique activation of the composite. High columbic efficiency (greater than 99%) upon cycling may indicate the formation of a stable SEI (solid-electrolyte interface) layer, which can contribute to long cycle life. The innovation in the current program, when further developed, will enable the system to maintain high energy and power densities at low temperatures, improve efficiency, and further stabilize and enhance the safety of the cell.

Hagh, Nader↗
DOE OSTI2021

Composite bilayer coatings for high capacity cathodes and anodes

An electrode comprises an electrode core. A composite bilayer coating is conformally disposed on the electrode core. The composite bilayer coating comprises a first layer disposed on at least a portion of the electrode core. The first layer comprises a metal fluoride, a metal oxide or a metal sulfide. A second layer is disposed on the first layer and comprises a metal fluoride, a metal oxide or a metal sulfide.

Mane, Anil U.↗
NASA NTRS1996

An aeroelastic analysis of helicopter rotor blades incorporating piezoelectric fiber composite twist actuation

A simple aeroelastic analysis of a helicopter rotor blade incorporating embedded piezoelectric fiber composite, interdigitated electrode blade twist actuators is described. The analysis consist of a linear torsion and flapwise bending model coupled with a nonlinear ONERA based unsteady aerodynamics model. A modified Galerkin procedure is performed upon the rotor blade partial differential equations of motion to develop a system of ordinary differential equations suitable for numerical integration. The twist actuation responses for three conceptual full-scale blade designs with realistic constraints on blade mass are numerically evaluated using the analysis. Numerical results indicate that useful amplitudes of nonresonant elastic twist, on the order of one to two degrees, are achievable under one-g hovering flight conditions for interdigitated electrode poling configurations. Twist actuation for the interdigitated electrode blades is also compared with the twist actuation of a conventionally poled piezoelectric fiber composite blade. Elastic twist produced using the interdigitated electrode actuators was found to be four to five times larger than that obtained with the conventionally poled actuators.

Wilkie, W. Keats↗