Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “cathode utilization”

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 271 records · Page 15
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Modeling Variable-Impedance, Magnetically Insulated, Transmission Lines

Coupling generator current to electron-beam loads and dynamic-inductance loads (z pinches) is greatly improved with low-inductance vacuum transmission lines. Typically, magnetically insulated transmission lines (MITLs) utilize nearly constant impedance geometries where the minimum impedance (anode-cathode gap) is limited by electron loss during the setup of magnetic insulation. Constant-impedance MITL designs are not optimized for low inductance (Zτ) when given a constraint on vacuum electron flow. We describe the design and the modeling of MITLs that have a nonconstant impedance. The baseline variable-impedance MITL designs are based on equilibrium vacuum-electron flow models [1] that are incorporated into the Screamer circuit code [2]. Such designs satisfy the MITL limits in the areal density of the loss current and have magnetically insulated flow that is stable everywhere along the MITL. Different MITL designs are then modeled analytically and with a 2-D particle-in-cell computer code in order to quantify subtle electron losses driven by changes to the vacuum impedance as a function of distance along the transmission line. We present a variable-impedance MITL design that delivers more current with a lower inductance than found in constant-impedance MITL designs.

47 OTHER INSTRUMENTATION↗
DOE OSTI2025

Halide segregation to boost all-solid-state lithium-chalcogen batteries

Mixing electroactive materials, solid-state electrolytes, and conductive carbon to fabricate composite electrodes is the most practiced but least understood process in all-solid-state batteries, which strongly dictates interfacial stability and charge transport. Here, we report on universal halide segregation at interfaces across various halogen-containing solid-state electrolytes and a family of high-energy chalcogen cathodes enabled by mechanochemical reaction during ultrahigh-speed mixing. Bulk and interface characterizations by multimodal synchrotron x-ray probes and cryo–transmission electron microscopy show that the in situ segregated lithium halide interfacial layers substantially boost effective ion transport and suppress the volume change of bulk chalcogen cathodes. Various all-solid-state lithium-chalcogen cells demonstrate utilization close to 100% and extraordinary cycling stability at commercial-level areal capacities.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Evaluation of Mg Compounds as Coating Materials in Mg Batteries

Mg batteries utilizing a Mg metal anode with a high-voltage intercalation cathode define a potential pathway toward energy storage with high energy density. However, the making of Mg batteries is plagued by the instability of existing electrolytes against the Mg-metal anode and high-voltage cathode materials. One viable solution to this problem is the identification of protective coating materials that could effectively separate the distinct chemistries of the metal-anode and the cathode materials from the electrolyte. Using first-principles calculations we mapped the electrochemical stability windows for non-redox-active Mg binary and ternary compounds in order to identify potential coating materials for Mg batteries. Our results identify Mg-halides and Mg(BH 4 ) 2 as promising anode coating materials based on their significant reductive stability. On the cathode side, we single out MgF 2 , Mg(PO 3 ) 2 , and MgP 4 O 11 as effective passivating agents.

25 ENERGY STORAGE↗
NASA NTRS2004

Assessment of High-Voltage Photovoltaic Technologies for the Design of a Direct Drive Hall Effect Thruster Solar Array

A three-year program to develop a Direct Drive Hall-Effect Thruster system (D2HET) begun in 2001 as part of the NASA Advanced Cross-Enterprise Technology Development initiative. The system, which is expected to reduce significantly the power processing, complexity, weight, and cost over conventional low-voltage systems, will employ solar arrays that operate at voltages higher than (or equal to) 300 V. The lessons learned from the development of the technology also promise to become a stepping-stone for the production of the next generation of power systems employing high voltage solar arrays. This paper summarizes the results from experiments conducted mainly at the NASA Marshal Space Flight Center with two main solar array technologies. The experiments focused on electron collection and arcing studies, when the solar cells operated at high voltages. The tests utilized small coupons representative of each solar array technology. A hollow cathode was used to emulate parts of the induced environment on the solar arrays, mostly the low-energy charge-exchange plasma (1012-1013 m-3 and 0.5-1 eV). Results and conclusions from modeling of electron collection are also summarized. The observations from the total effort are used to propose a preliminary, new solar array design for 2 kW and 30-40 kW class, deep space missions that may employ a single or a cluster of Hall- Effect thrusters.

Mikellides, I. G.↗
DOE OSTI2024

Transport–Friendly Microstructure in SSC–MEA: Unveiling the SSC Ionomer–Based Membrane Electrode Assemblies for Enhanced Fuel Cell Performance

The significant role of the cathodic binder in modulating mass transport within the catalyst layer (CL) of fuel cells is essential for optimizing cell performance. This investigation focuses on enhancing the membrane electrode assembly (MEA) through the utilization of a short-side-chain perfluoro-sulfonic acid (SSC-PFSA) ionomer as the cathode binder, referred to as SSC-MEA. This study meticulously visualizes the distinctive interpenetrating networks of ionomers and catalysts, and explicitly clarifies the triple-phase interface, unveiling the transport-friendly microstructure and transport mechanisms inherent in SSC-MEA. The SSC-MEA exhibits advantageous microstructural features, including a better-connected ionomer network and well-organized hierarchical porous structure, culminating in superior mass transfer properties. Relative to the MEA bonded by long-side-chain perfluoro-sulfonic acid (LSC-PFSA) ionomer, noted as LSC-MEA, SSC-MEA exhibits a notable peak power density (1.23 W cm –2 ), efficient O 2 transport, and remarkable proton conductivity (65% improvement) at 65 °C and 70% relativity humidity (RH). These findings establish crucial insights into the intricate morphology-transport-performance relationship in the CL, thereby providing strategic guidance for developing highly efficient MEA.

25 ENERGY STORAGE↗
DOE OSTI2022

Benchmarking Solid-State Batteries Containing Sulfide Separators: Effects of Electrode Composition and Stack Pressure

Integrating sulfide separators into solid-state batteries (SSBs) containing high energy cathodes typically requires one or more materials and engineering solutions including: (i) applying interfacial coatings to mitigate electrolyte decomposition, (ii) applying high stack pressures to form robust solid-solid contacts, and (iii) using alloying anodes to avoid Li dendrite formation. Despite the promise of these approaches, a lack of standardized testing protocols makes it difficult to directly compare results among different studies. To address this problem, the present work benchmarks the performance of SSBs containing β-Li 3 PS 4 (LPS) separators and composite cathodes. By systematically varying the anode/cathode composition and stack pressure, this work demonstrates that cathode design is a major bottleneck for solid-state cells cycled at low rates (<100 µA cm -2 ). Operando stack pressure measurements show that, while mechanical confinement generally promotes higher active material utilization and cycling stability, this strategy alone does not address interfacial reactivity between LPS and high voltage cathodes. Here, these results also demonstrate that stress evolution during cycling is dominated by volume changes at the Li metal anode. Finally, we show that FeS 2 cathodes with moderate operating voltages (<3 V vs Li/Li + ) exhibit superior cycling performance compared to high voltage cathodes by facilitating formation of stable cathode/electrolyte interfaces.

25 ENERGY STORAGE↗
DOE OSTI2025

Solvent‐Phobic and Ionophilic Carboxylated Polythiophene Layer for Fluoride‐Rich Cathode Electrolyte Interphase

Abstract One focal area of contemporary organic mixed ionic‐electronic conductor (OMIEC) research relates to utilization of dual‐conductive properties to enhance the ion/electron transfer kinetics for energy storage applications. Insight regarding OMIEC response toward the electrolyte anion and solvent used in lithium‐ion batteries (LIBs), however, is limited. Here, for the first time, the solvent‐phobic and ionophilic (SP‐IP) properties of the OMIEC, poly[3‐(potassium‐4‐butanoate)thiophene‐2,5‐diyl] (P3KBT), are revealed through comprehensive evaluation and characterization. The solvent‐phobic characteristics arise from the cooperation of dispersive interaction, polar interaction, and hydrogen‐bonding between P3KBT and electrolyte solvent. The ionophilic nature is driven by electrostatic interactions between P3KBT side chain carboxylate groups and LiPF 6 , and the reversible electrochemical doping/de‐doping of the polythiophene backbone with PF 6 ⁻ . The SP‐IP properties induce formation of a LiF‐ rich , Li 2 CO 3 ‐ limited cathode electrolyte interphase (CEI) layer when a P3KBT coating layer is applied to the active material surface, significantly improving half‐cell life to over 1500 cycles at 2C.

Ren, Haoze [Department of Chemical and Bimolecular↗
DOE OSTI2024

Mechanochemically Robust LiCoO 2 with Ultrahigh Capacity and Prolonged Cyclability

Pushing intercalation-type cathode materials to their theoretical capacity often suffers from fragile Li-deficient frameworks and severe lattice strain, leading to mechanical failure issues within the crystal structure and fast capacity fading. This is particularly pronounced in layered oxide cathodes because the intrinsic nature of their structures is susceptible to structural degradation with excessive Li extraction, which remains unsolved yet despite attempts involving elemental doping and surface coating strategies. Herein, a mechanochemical strengthening strategy is developed through a gradient disordering structure to address these challenges and push the LiCoO 2 (LCO) layered cathode approaching the capacity limit (256 mAh g -1 , up to 93% of Li utilization). This innovative approach also demonstrates exceptional cyclability and rate capability, as validated in practical Ah-level pouch full cells, surpassing the current performance benchmarks. Comprehensive characterizations with multiscale X-ray, electron diffraction, and imaging techniques unveil that the gradient disordering structure notably diminishes the anisotropic lattice strain and exhibits high fatigue resistance, even under extreme delithiation states and harsh operating voltages. Consequently, this designed LCO cathode impedes the growth and propagation of particle cracks, and mitigates irreversible phase transitions. In conclusion, this work sheds light on promising directions toward next-generation high-energy-density battery materials through structural chemistry design.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Local structure and ion storage properties of vanadate cathode materials regulated by the pre-alkalization

Aqueous Zn-ion batteries using mild acidic electrolytes utilizing a Zn 2+ /H + dual-ion storage mechanism have shown great potential in achieving high energy density comparable to non-aqueous lithium-ion batteries. Here, this study reveals that hydrated alkali-ions regulate the formation of alkali-intercalated vanadate layered compounds. Among various vanadate materials, lithium-intercalated vanadate has the largest interlayer spacing and most disordered local structure, exhibiting the largest storage capacity of 308 mA h g –1 at 0.05 A g –1 for Zn 2+ /H + dual-ion storage and improved charge transfer and transport kinetics and cycling performance, evidenced by in situ X-ray diffraction and ex situ X-ray total scattering and pair distribution function analysis. Our study provides new insight into designing layered vanadate materials for high-capacity aqueous batteries.

25 ENERGY STORAGE↗
NASA NTRS1994

Multiple Hollow Cathode Wear Testing

A hollow cathode-based plasma contactor has been baselined for use on the Space Station to reduce station charging. The plasma contactor provides a low impedance connection to space plasma via a plasma produced by an arc discharge. The hollow cathode of the plasma contactor is a refractory metal tube, through which xenon gas flows, which has a disk-shaped plate with a centered orifice at the downstream end of the tube. Within the cathode, arc attachment occurs primarily on a Type S low work function insert that is next to the orifice plate. This low work function insert is used to reduce cathode operating temperatures and energy requirements and, therefore, achieve increased efficiency and longevity. The operating characteristics and lifetime capabilities of this hollow cathode, however, are greatly reduced by oxygen bearing contaminants in the xenon gas. Furthermore, an optimized activation process, where the cathode is heated prior to ignition by an external heater to drive contaminants such as oxygen and moisture from the insert absorbed during exposure to ambient air, is necessary both for cathode longevity and a simplified power processor. In order to achieve the two year (approximately 17,500 hours) continuous operating lifetime requirement for the plasma contactor, a test program was initiated at NASA Lewis Research Center to demonstrate the extended lifetime capabilities of the hollow cathode. To date, xenon hollow cathodes have demonstrated extended lifetimes with one test having operated in excess of 8000 hours in an ongoing test utilizing contamination control protocols developed by Sarver-Verhey. The objectives of this study were to verify the transportability of the contamination control protocols developed by Sarver-Verhey and to evaluate cathode contamination control procedures, activation processes, and cathode-to-cathode dispersions in operating characteristics with time. These were accomplished by conducting a 2000 hour wear test of four hollow cathodes with different xenon gas purities and activation processes. The following will be presented: a description of the facility and test hardware, testing procedures and operating conditions, a discussion of test results, and conclusions.

Soulas, George C.↗
DOE OSTI2019

Commercialization of Lithium Battery Technologies for Electric Vehicles

We present that the currently commercialized lithium-ion batteries have allowed for the creation of practical electric vehicles, simultaneously satisfying many stringent milestones in energy density, lifetime, safety, power, and cost requirements of the electric vehicle economy. The next wave of consumer electric vehicles is just around the corner. Although widely adopted in the vehicle market, lithium-ion batteries still require further development to sustain their dominating roles among competitors. In this review, the authors survey the state-of-the-art active electrode materials and cell chemistries for automotive batteries. The performance, production, and cost are included. The advances and challenges in the lithium-ion battery economy from the material design to the cell and the battery packs fitting the rapid developing automotive market are discussed in detail. Additionally, new technologies of promising battery chemistries are comprehensively evaluated for their potential to satisfy the targets of future electric vehicles.

25 ENERGY STORAGE↗
DOE OSTI2024

Improved cycle stability and high-rate capability of LiNbO 3 -coated Li 3 VO 4 as anode material for lithium-ion battery

Lithium vanadate (Li 3 VO 4 ) has garnered considerable attention as an alternative negative electrode material for non-aqueous lithium-ion batteries due to its high capacity, energy efficiency, and stable discharge voltage. Nonetheless, the Li 3 VO 4 material displays a low rate capability, attributed mainly to its poor intrinsic electronic conductivity. Here, in this study, we report the synthesis of lithium niobate LiNbO 3 -coated Li 3 VO 4 (LVO@LNO) using a one-pot sol-gel method. The resulting LVO@LNO demonstrates a high reversible capacity of approximately 530 mAh/g, which is more than double that of free Li 3 VO 4 . To explore the effect of the LNO coating process on the morphological and structural properties, Raman, XRD, operando XRD, XPS, SEM and HTEM analyses were conducted. To explain the enhancement of electronic conductivity in our modified material after a LiNbO 3 coating, we conducted an Ex-Situ electrochemical impedance (EIS) and Density Functional Theory (DFT) computational study. Additionally, we designed a full cell utilizing a 1 wt% LNO-coated LVO anode and NMC-811 cathode. The cell yielded an output voltage of approximately 2.8 V with a high initial specific capacity of 350 mAh/g versus to the anode, at 1C with a capacity retention of 85 % after 100 cycles.

25 ENERGY STORAGE↗
DOE OSTI2025

Single-Phase Spinel NiCo 2 O 4 as Highly Active and Stable Electrocatalysts for Urea Oxidation Reaction in Urea Electrolysis

Exploring and designing a stable and active catalyst for the urea electro-oxidation reaction (UOR, CO(NH 2 ) 2 + 6OH – → CO 2 + N 2 + 5H 2 O + 6e – ) is crucial for the long-term sustainability of ecological systems and clean energy production. We found that spinel NiCo 2 O 4 is a stable and active electrocatalyst for UOR at a relatively low anodic potential without triggering the competing oxygen evolution reaction (OER). A urea electrolysis cell (CO(NH 2 )2 + H 2 O → CO 2 + N 2 + 2H 2 ) utilizing a spinel NiCo 2 O 4 anode and a commercial Pt cathode was further characterized through galvanostatic polarization tests, demonstrating excellent structural stability at various current densities. Post-mortem analysis of long-term urea electrolysis measurements suggested that NiCo 2 O 4 electrocatalysts maintained a stable spinel structure. However, redistribution of Ni 3+ to Ni 2+ valence on the catalyst surface was observed, in contrast to the intact Co valence, indicating that (i) Ni sites are active toward urea adsorption and sequential electro-oxidation; (ii) while urea oxidation proceeds primarily through the direct electro-oxidation mechanism, chemical reactions between the Ni 3+ site and urea occur during long-term electrochemical UOR operation. Density functional theory (DFT) simulations were used to calculate the adsorption energies of urea molecules on NiO, Co 3 O 4 , and NiCo 2 O 4 , revealing the importance of regulating the configuration of adsorbed urea molecules on the NiCo 2 O 4 surface.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Understanding the critical chemistry to inhibit lithium consumption in lean lithium metal composite anodes

Lithium metal has been deemed by many as the “Holy Grail” of anode materials due to its high theoretical capacity (~3860 mA h g -1 ), redox potential of -3.040 V vs. SHE, and light weight. The goal of this work is to investigate the relationship between a lean lithium metal anode and its consumption as a function of host materials, electrochemical protocol and electrolyte composition. With the use of carbon nanofibers, lithium metal has been electrodeposited onto the host matrix and used in a battery with a LiNi 0.6 Mn 0.2 Co 0.2 O 2 cathode. The mass-loading of lithium can be easily controlled and utilized to investigate the practicality of an anode limited battery (i.e., limited lithium with an effective thickness <15 μm) in a high surface area matrix. We then quantify the consumption rate of active lithium using different electrolyte additives and current rates in full cells and observe that the lithium consumption behavior in an anode-limited cell is different from that in an anode-excess cell. Our results highlight the necessity of applying truly lithium-limited cells when evaluating the electrochemical properties of lithium anodes and electrolyte additives. By extending this method to a standard graphite host, full cells can retain 75% of their initial capacities after 1000 cycles. The present study demonstrates the importance of graphitic carbon in increasing the lifespan of limited lithium (<15 μm) for practical lithium metal batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Mitigating X-ray-induced damage for accurate analysis of battery cathodes using transmission X-ray microscopy

Here, we investigate the impact of X-ray-induced damage on the evolution of battery cathodes using synchrotron transmission X-ray microscopy. In an operando coin cell, exposure to the X-ray beam can induce bubble formation, potentially rendering cathode particles electrochemically inactive and displacing particles from their initial position. However, utilizing external pressure on a pouch cell can mitigate bubble formation and its associated effects.

25 ENERGY STORAGE↗
NASA NTRS1969

Time-shared Cathode Ray Tube

Time-shared cathode tube provides high quality display at low cost display stations which utilize television moniters. It updates a cluster of graphic displays from a computer and is useful in systems not equipped for graphics time-sharing.

Herndon, E. S.↗
NASA NTRS1975

Hydrogen-Bromine Secondary Battery

A secondary battery is described utilizing hydrogen and halogen as primary reactants. It comprises inert anode and cathode initially contacting an aqueous solution of an acid and an alkali metal bromide. The hydrogen generated during charging of the cell is stored as gas, while the bromine becomes dissolved predominantly in the lower layers of the acid electrolyte. Preferred components are phosphoric acid and lithium bromide.

England, C.↗