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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
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↗
NASA NTRS1988

Electrode erosion in steady-state electric propulsion engines

The anode and cathode of a 30 kW class arcjet engine were sectioned and analyzed. This arcjet was operated for a total time of 573 hr at power levels between 25 and 30 kW with ammonia at flow rates of 0.25 and 0.27 gm/s. The accumulated run time was sufficient to clearly establish erosion patterns and their causes. The type of electron emission from various parts of the cathode surface was made clear by scanning electron microscope analysis. A scanning electron microscope was used to study recrystallization on the hot anode surface. These electrodes were made of 2 percent thoriated tungsten and the surface thorium content and gradient perpendicular to the surfaces was determined by quantitative microprobe analysis. The results of this material analysis on the electrodes and recommendations for improving electrode operational life time are presented.

Pivirotto, Thomas J.↗
NASA NTRS2018

Preparation for Hollow Cathode Testing for the Advanced Electric Propulsion System at NASA Glenn Research Center

NASA Glenn Research Center is performing activities to support the unique needs of hollow cathode development and testing for the Advanced Electric Propulsion System (AEPS). Three existing vacuum facilities have been outfitted as cathode test facilities, and each will serve a different role in upcoming testing. Vacuum Facility 67 is being developed to serve as a long-duration test facility for the Engineering Development Unit cathode, which is to be delivered by the AEPS contractor. It will feature a thruster-like magnetic field simulator and cold-cycle capability via a liquid nitrogen-cooled cold plate. Vacuum Facility 17 is being developed as a test facility for short- to medium-duration experiments in order to provide auxiliary support for the long-duration testing. It will feature a magnetic field simulator but not cold-cycling. Finally, Vacuum Facility 1 will be a high-pumping speed cathode development environment, and will feature an array of plasma and temperature diagnostics. In addition to the facility preparation work, a new cathode, referred to as the Mark II, has been designed. The Mark II is an evolution of the Technology Demonstration Unit cathodes that better evokes the geometry, fabrication, and construction of the forthcoming Engineering Development Unit. This cathode serves as a transition between the Technology Demonstration Unit cathodes used during early thruster development and the forthcoming Engineering Development Unit cathodes. It will be used as a means of verifying the new test facilities prior to arrival of Engineering Development Unit hardware. Details of the Mark II design and key features are presented, as well as details of future work to be performed.

Hall, Scott J.↗
NASA NTRS2018

Preparation for Hollow Cathode Testing for the Advanced Electric Propulsion System at NASA Glenn Research Center

NASA Glenn Research Center is performing activities to support the unique needs of hollow cathode development and testing for the Advanced Electric Propulsion System (AEPS). Three existing vacuum facilities have been outfitted as cathode test facilities, and each will serve a different role in upcoming testing. Vacuum Facility 67 is being developed to serve as a long-duration test facility for the Engineering Development Unit cathode, which is to be delivered by the AEPS contractor. It will feature a thruster-like magnetic field simulator and cold-cycle capability via a liquid nitrogen-cooled cold plate. Vacuum Facility 17 is being developed as a test facility for short- to medium-duration experiments in order to provide auxiliary support for the long-duration testing. It will feature a magnetic field simulator but not cold-cycling. Finally, Vacuum Facility 1 will be a high-pumping speed cathode development environment, and will feature an array of plasma and temperature diagnostics. In addition to the facility preparation work, a new cathode, referred to as the Mark II, has been designed. The Mark II is an evolution of the Technology Demonstration Unit cathodes that better evokes the geometry, fabrication, and construction of the forthcoming Engineering Development Unit. This cathode serves as a transition between the Technology Demonstration Unit cathodes used during early thruster development and the forthcoming Engineering Development Unit cathodes. It will be used as a means of verifying the new test facilities prior to arrival of Engineering Development Unit hardware. Details of the Mark II design and key features are presented, as well as details of future work to be performed.

Advanced Electric Propulsion System (AEPS)↗
NASA NTRS2018

Preparation for Hollow Cathode Testing for the Advanced Electric Propulsion System at NASA Glenn Research Center

NASA Glenn Research Center is performing activities to support the unique needs of hollow cathode development and testing for the Advanced Electric Propulsion System (AEPS). Three existing vacuum facilities have been outfitted as cathode test facilities, and each will serve a different role in upcoming testing. Vacuum Facility 67 is being developed to serve as a long-duration test facility for the Engineering Development Unit cathode, which is to be delivered by the AEPS contractor. It will feature a thruster-like magnetic field simulator and cold-cycle capability via a liquid nitrogen-cooled cold plate. Vacuum Facility 17 is being developed as a test facility for short- to medium-duration experiments in order to provide auxiliary support for the long-duration testing. It will feature a magnetic field simulator but not cold-cycling. Finally, Vacuum Facility 1 will be a high-pumping speed cathode development environment, and will feature an array of plasma and temperature diagnostics. In addition to the facility preparation work, a new cathode, referred to as the Mark II, has been designed. The Mark II is an evolution of the Technology Demonstration Unit cathodes that better evokes the geometry, fabrication, and construction of the forthcoming Engineering Development Unit. This cathode serves as a transition between the Technology Demonstration Unit cathodes used during early thruster development and the forthcoming Engineering Development Unit cathodes. It will be used as a means of verifying the new test facilities prior to arrival of Engineering Development Unit hardware. Details of the Mark II design and key features are presented, as well as details of future work to be performed.

Hall, Scott J.↗
DOE OSTI2026

Engineering Microstructure in Dry-Processed Cathodes Via Calendering

Calendering serves as a multifunctional step in dry electrode processing that not only densifies the electrode but also induces polytetrafluoroethylene (PTFE) fibrillation and reorganizes the microstructure. These coupled effects are essential for achieving electrical connectivity and sufficient cohesion, yet they also introduce trade-offs, such as active material particle fracture, pore collapse, and excessive porosity loss, that can hinder ionic transport. This research systematically maps the calendering parameter space for LiNi0.6Mn0.2Co0.2O2 (NMC622) dry cathodes with a target thickness of ∼100 µm and porosity of ∼30% by varying roll gaps, roll temperature, roll speed, and the number of passes. A practical processing window for this formulation and electrode architecture is identified that achieves sufficient PTFE fibrillation and strong interfacial contact while minimizing particle fracture and preserving the porosity required for efficient ionic transport. In particular, gradual-gap calendering with moderate per-pass compression mitigates fracture and pore collapse while still reaching the target thickness with reasonable throughput, and slower roll speeds with modest roll temperatures further reduce mechanical damage. These results provide actionable guidance for scaling NMC622-based thick dry-processed cathodes.

Park, Hyunji↗
NASA NTRS2005

Destructive physical analysis of hollow cathodes from the Deep Space 1 Flight spare ion engine 30,000 hr life test

Destructive physical analysis of the discharge and neutralizer hollow cathode assemblies from the Deep Space 1 Flight Spare 30,000 Hr life test was performed to characterize physical and chemical evidence of operationally induced effects after 30,372 hours of operation with beam extraction. Post-test inspection of the discharge-cathode assembly was subdivided into detailed analyses at the subcomponent level. Detailed materials analysis and optical inspection of the insert, orifice plate, cathode tube, heater, keeper assembly, insulator, and low-voltage propellant isolator were performed. Energy dispersive X-ray (EDX) and scanning electron microscopy (SEW analyses were used to determine the extent and composition of regions of net deposition and erosion of both the discharge and neutralizer inserts. A comparative approach with an un-operated 4:1:1 insert was used to determine the extent of impregnate material depletion as a function of depth from the ID surface and axial position from the orifice plate. Analysis results are compared and contrasted with those obtained from similar analyses on components from shorter term tests, and provide insight regarding the prospect for successful longer-term operation consistent with SOA ion engine program life objectives at NASA.

cathodes↗
NASA NTRS1995

Integration issues of a plasma contactor Power Electronics Unit

A hollow cathode-based plasma contactor is baselined on International Space Station Alpha (ISSA) for spacecraft charge control. The plasma contactor system consists of a hollow cathode assembly (HCA), a power electronics unit (PEU), and an expellant management unit (EMU). The plasma contactor has recently been required to operate in a cyclic mode to conserve xenon expellant and extend system life. Originally, a DC cathode heater converter was baselined for a continuous operation mode because only a few ignitions of the hollow cathode were expected. However, for cyclic operation, a DC heater supply can potentially result in hollow cathode heater component failure due to the DC electrostatic field. This can prevent the heater from attaining the proper cathode tip temperature for reliable ignition of the hollow cathode. To mitigate this problem, an AC cathode heater supply was therefore designed, fabricated, and installed into a modified PEU. The PEU was tested using resistive loads and then integrated with an engineering model hollow cathode to demonstrate stable steady-state operation. Integration issues such as the effect of line and load impedance on the output of the AC cathode heater supply and the characterization of the temperature profile of the heater under AC excitation were investigated.

Pinero, Luis R.↗
DOE OSTI2025

Intralattice-bonded phase-engineered ultrahigh-Ni single-crystalline cathodes suppress strain evolution

Single crystallization remains a debated strategy for advancing Ni-rich cathode materials. While it mitigates particle cracking and improves tap density by eliminating particle boundaries, extended diffusion pathways introduce volumetric and lattice distortions, compromising electrochemical and structural stability. These challenges hinder the commercialization of high-Ni single-crystal cathodes, calling for a reassessment of their viability. Here, in this study, we report a structural design: intralattice-bonded phase single-crystal LiNi 0.92 Co 0.03 Mn 0.05 O 2 (IBP-SC92). This architecture maintains structural integrity while shortening diffusion pathways, resulting in almost zero electrochemical degradation during cycling. The robust structure and fast ion transport mitigate lattice strain, as confirmed by multiscale high-resolution diffraction and imaging techniques, preventing intragranular cracks and irreversible phase transitions. As a result, IBP-SC92 shows outstanding cycling stability, with nearly 100% capacity retention after 100 cycles in half cells and 94.5% retention after 1,000 cycles in full cells. This redefined single-crystal cathode represents a significant step towards the industrial adoption of high-energy-density materials.

36 MATERIALS SCIENCE↗
NASA NTRS1976

Cycle life testing of 8-cm mercury ion thruster cathodes

Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. The cycle life test results are presented along with results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

Wintucky, E. G.↗
NASA NTRS1976

Cycle life testing of 8-cm mercury ion thruster cathodes

Two main cathodes have successfully completed 2800 and 1980 cycles and three neutralizers, 3928, 3050, and 2850 cycles in ongoing cycle life tests of flight-type cathode-isolator-vaporizer and neutralizer-isolator-vaporizer assemblies for the 4.45 mN 8-cm Hg ion thruster system. Each cycle included one hour of cathode operation. Starting and operating conditions simulated those expected in a typical auxiliary propulsion mission duty cycle. This paper presents the cycle life test results and also results of an insert comparison test which led to the selection of a rolled foil insert type for the 8-cm Engineering Model Thruster cathodes.

Wintucky, E. G.↗
DOE OSTI2025

Advanced All-Fluorinated Electrolytes for Extended Cycle Life and Stability of Li||SPAN Batteries

Achieving long-term stability and consistent capacity in lithium (Li) metal batteries with sulfurized polyacrylonitrile (SPAN) cathodes requires precisely engineered electrolytes to optimize interphase formation and redox reversibility. Here, this study presents 1,1-difluoro-2-(2-methoxyethoxy)ethane (DFE)-based localized high-concentration electrolytes (LHCEs), incorporating fluorinated components such as salt, solvating solvent, and diluent for improved electrode stability. Molecular dynamics simulations and surface analyses reveal that the DFE-LHCE with 1,2-bis(1,1,2,2-tetrafluoroethoxy)ethane (BTFEE) diluent produces uniform and robust interphase layers on both cathode and anode, enriched with inorganic species like LiF and Li 2 O. These properties lead to prolonged redox reversibility of the SPAN cathode, suppressed side reactions, and extended cycle life for Li||SPAN cells. Remarkably, DFE-BTFEE-LHCE enables Li||SPAN coin cells with an areal capacity of ∼7 mAh cm -2 for SPAN to retain 81.3% capacity after 200 cycles and pouch cells of 0.12 Ah with 8 mAh cm -2 of SPAN and lean electrolyte to maintain 96.4% capacity over 80 cycles. These findings pave the way for advancing Li||SPAN battery technologies.

25 ENERGY STORAGE↗
NASA NTRS1994

The NASA-JPL advanced propulsion program

The NASA Advanced Propulsion Concepts (APC) program at the Jet Propulsion Laboratory (JPL) consists of two main areas: The first involves cooperative modeling and research activities between JPL and various universities and industry; the second involves research at universities and industry that is directly supported by JPL. The cooperative research program consists of mission studies, research and development of ion engine technology using C-60 (Buckminsterfullerene) propellant, and research and development of lithium-propellant Lorentz-force accelerator (LFA) engine technology. The university/industry- supported research includes research (modeling and proof-of-concept experiments) in advanced, long-life electric propulsion, and in fusion propulsion. These propulsion concepts were selected primarily to cover a range of applications from near-term to far-term missions. For example, the long-lived pulsed-xenon thruster research that JPL is supporting at Princeton University addresses the near-term need for efficient, long-life attitude control and station-keeping propulsion for Earth-orbiting spacecraft. The C-60-propellant ion engine has the potential for good efficiency in a relatively low specific impulse (Isp) range (10,000 - 30,000 m/s) that is optimum for relatively fast (less than 100 day) cis-lunar (LEO/GEO/Lunar) missions employing near-term, high-specific mass electric propulsion vehicles. Research and modeling on the C-60-ion engine are currently being performed by JPL (engine demonstration), Caltech (C-60 properties), MIT (plume modeling), and USC (diagnostics). The Li-propellant LFA engine also has good efficiency in the modest Isp range (40,000 - 50,000 m/s) that is optimum for near-to-mid-term megawatt-class solar- and nuclear-electric propulsion vehicles used for Mars missions transporting cargo (in support of a piloted mission). Research and modeling on the Li-LFA engine are currently being performed by JPL (cathode development), Moscow Aviation Institute (engine testing), Thermacore (electrode development), as well as at MIT (plume modeling), and USC (diagnostics). Also, the mission performance of a nuclear-electric propulsion (NEP) Li-LFA Mars cargo vehicle is being modeled by JPL (mission analysis; thruster and power processor modeling) and the Rocketdyne Energy Technology and Engineering Center (ETEC) (power system modeling). Finally, the fusion propulsion research activities that JPL is supporting at Pennsylvania State University (PSU) and at Lawrenceville Plasma Physics (LPP) are aimed at far-term fast (less than 100 day round trip) piloted Mars missions and, in the very far term, interstellar missions.

Frisbee, Robert H.↗
DOE OSTI2024

Surface Atomic Rearrangement with High Cation Ordering for Ultra-Stable Single-Crystal Ni-Rich Co-Less Cathode Materials

It is crucial to minimize cobalt content in Ni-rich layered single-crystal cathodes due to their high price and limited availability, yet it will inevitably lead to cation disordering, capacity degradation, and thermal issues. Herein, to overcome the intrinsic trade-off between performance and composition of Ni-rich Co-less single-crystal cathodes, a precursor engineering strategy with an epitaxially grown cobalt enrichment on the surface is innovatively proposed. In contrast to traditional coating modifications with random orientation and rigid surface-bulk boundary, the epitaxially enriched surface cobalt layer on the precursor undergoes rapid interdiffusion with the internal Ni 3+ during the optimized sintering process. This interdiffusion eliminates the surface-bulk boundary, promoting the uniform distribution of cobalt and synergistically addressing the Li/Ni intermixing. Moreover, an enhanced surface Li + diffusion is obtained, thereby suppressing the Li + concentration gradient and intragranular cracks generation. Consequently, the modified LiNi 0.7 Co 0.07 Mn 0.23 O 2 exhibits impressive cycling stability with increased capacity retention in both coin-type half-cells and pouch-type full-cells (91% after 1000 cycles), even under the harsh condition of high-temperature, surpassing the majority of previously reported Ni-rich cathodes. Finally, this work opens new avenues toward the low cost, high energy density, thermal stability, and long cyclic life for Ni-rich Co-less cathodes and sheds light on large-scale commercial production.

25 ENERGY STORAGE↗