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At least 721 records · Page 40

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NASA NTRS2006

Effects of an internally-mounted cathode on hall thruster plume properties

The effects of cathode position on the plume properties of an 8 kW BHT-8000 Busek Hall thruster are discussed. Experiments were conducted at the Jet Propulsion Laboratory (JPL) in a vacuum chamber suitable for the development and qualification of high-power Hall thrusters. Multi-mode Hall thruster operation was demonstrated at operating conditions ranging from 200-500 V discharge voltage, 10-40 A discharge current, and 2-8 kW discharge power. Reductions in plume divergence and increased near-field plume symmetries were found to result from the use of an internally-mounted cathode instead of the traditional externally-mounted configuration. High-current hollow cathodes developed at JPL utilizing lanthanum hexaboride (LaB6) emitters were also demonstrated. Discharge currents up to 100 A were achieved with the cathode operating alone and up to 40 A during operation with the Hall thruster. LaB6 cathodes were investigated because of their potential to reduce overall system cost and risk due to less stringent xenon purity and handling requirements.

Fitzgerald, Dennis J.↗

DOE OSTI2015

Vacuum encapsulated, high temperature diamond amplified cathode capsule and method for making same

A vacuum encapsulated, hermetically sealed cathode capsule for generating an electron beam of secondary electrons, which generally includes a cathode element having a primary emission surface adapted to emit primary electrons, an annular insulating spacer, a diamond window element comprising a diamond material and having a secondary emission surface adapted to emit secondary electrons in response to primary electrons impinging on the diamond window element, a first high-temperature solder weld disposed between the diamond window element and the annular insulating spacer and a second high-temperature solder weld disposed between the annular insulating spacer and the cathode element. The cathode capsule is formed by a high temperature weld process under vacuum such that the first solder weld forms a hermetical seal between the diamond window element and the annular insulating spacer and the second solder weld forms a hermetical seal between the annular spacer and the cathode element whereby a vacuum encapsulated chamber is formed within the capsule.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

DOE OSTI2016

Modeling Co-Extruded Cathodes for High Energy Lithium-Ion Batteries

Utilizing an existing macro-homogeneous porous electrode model developed by John Newman, this talk presents the potential energy density gains that can be realized in lithium-ion battery electrodes fabricated with co-extrusion (CoEx) technology. CoEx uses carefully engineered fluidic channels to cause multiple streams of dissimilar fluids to impart shape to one another. The result is a high-speed, continuous deposition process that can create fine linear structures much smaller than the smallest physical feature within the printhead. By eliminating the small channels necessary for conventional extrusion and injection processes, CoEx is able to deposit highly loaded and viscous pastes at high line speeds under reasonable operating pressures. The CoEx process is capable of direct deposition of features as small as 10 μm with aspect ratios of 5 or greater, and print speeds > 80 ft/min. We conduct an analysis on two-dimensional cathode cross-sections in COMSOL and present the electrochemical performance results, including calculated volumetric energy capacity for Lithium Nickel Manganese Cobalt Oxide (NMC) co-extruded cathodes, in the presence of a lithium metal anode, polymer separator and ethylene carbonate–diethyl carbonate (EC:DEC) liquid electrolyte. The impact of structured electrodes on cell performance is investigated by varying the physical distribution of a fixed amount of cathode mass over a space of dimensions which can be fabricated by CoEx. By systematically varying the thickness and aspect ratio of the electrode structures, we present an optimal subset of geometries and design rules for co-extruded geometries. Modeling results demonstrate that NMC CoEx cathodes, on the order of 125-200 µm thick, can garner an improvement in material utilization and in turn capacity through the addition of fine width electrolyte channels or highly conductive electrode regions. We also present initial experimental results on CoEx NMC cathode structures.

25 ENERGY STORAGE↗

DOE OSTI2017

Lipon coatings for high voltage and high temperature Li-ion battery cathodes

A lithium ion battery includes an anode and a cathode. The cathode includes a lithium, manganese, nickel, and oxygen containing compound. An electrolyte is disposed between the anode and the cathode. A protective layer is deposited between the cathode and the electrolyte. The protective layer includes pure lithium phosphorus oxynitride and variations that include metal dopants such as Fe, Ti, Ni, V, Cr, Cu, and Co. A method for making a cathode and a method for operating a battery are also disclosed.

25 ENERGY STORAGE↗

DOE OSTI2017

Lipon coatings for high voltage and high temperature Li-ion battery cathodes

25 ENERGY STORAGE↗

DOE OSTI2018

Triple conducting cathode material for intermediate temperature protonic ceramic electrochemical devices

The present invention relates to a protonic ceramic fuel cell, a cathode for a protonic ceramic fuel cell, and a method of making the same. More specifically, the cathode for a protonic ceramic fuel cell utilizes a phase-pure perovskite structure of the compound BaCo 0.4 Fe 0.4 Zr 0.2-x Y x O 3- delta., where x is between about 0 and about 0.2. The cathode material may then be utilized in a PCFC as either a thin film porous cathode or as nanoparticles infiltrated into a cathode bone having a different structure.

Tong, Jianhua↗

DOE OSTI2018

Cathode material for low temperature solid oxide fuel cells

The present invention relates to a solid oxide (or protonic ceramic) fuel cell, a cathode for a solid oxide (or protonic ceramic) fuel cell, and a method of making the same. More specifically, the cathode for a solid oxide (or protonic ceramic) fuel cell utilizes a phase-pure perovskite structure of the compound BaCo.sub.0.4Fe.sub.0.4Zr.sub.0.2-xY.sub.xO.sub.3-.delta., where x is between about 0 and about 0.2. The cathode material may then be utilized in a SOFT or a PCFC as either a thin film porous cathode or as nanoparticles infiltrated into a cathode bone having a different structure.

36 MATERIALS SCIENCE↗

DOE OSTI2018

Composition of a nickelate composite cathode for a fuel cell

In some embodiments, a solid oxide fuel cell comprising an anode, an electrolyte, cathode barrier layer, a nickelate composite cathode separated from the electrolyte by the cathode barrier layer, and a cathode current collector layer is provided. The nickelate composite cathode includes a nickelate compound and second oxide material, which may be an ion conductor. The composite may further comprise a third oxide material. The composite may have the general formula (Ln u M1 v M2 s ) n+1 (Ni 1-t N t ) n O 3n+1 -A 1-x B x O y --C. w D z Ce (1-w-z) O 2-δ , wherein A and B may be rare earth metals excluding ceria.

25 ENERGY STORAGE↗

DOE OSTI2019

High capacity and stable cathode materials

High energy density cathode materials, such as LiNiXMnYCoZO2 (NMC) cathode materials, with improved discharge capacity (hence energy density) and enhanced cycle life are described. A solid electrolyte, such as lithium phosphate infused inside of secondary particles of the cathode material demonstrates significantly enhanced structural integrity without significant or without any observable particle cracking occurring during charge/discharge processes, showing high capacity retention of more than 90% after 200 cycles at room temperature. In certain embodiments the disclosed cathode materials (and cathodes made therefrom) are formed using nickel-rich NMC and/or are used in a battery system with a non-aqueous dual-Li salt electrolytes.

25 ENERGY STORAGE↗

DOE OSTI2019

Protective cathode coatings for lithium-ion batteries

Cathode coatings for lithium ion batteries, cathodes coated with the coatings, and lithium ion batteries incorporating the coated cathodes are provided. The coatings, which are composed of binary, ternary, and higher order metal oxides and/or metalloid oxides, can reduce the hydrofluoric acid (HF)-induced degradation of the electrolyte and/or cathodes, thereby improving the performance of lithium ion batteries, relative to lithium ion batteries that employ bare cathodes.

Aykol, Muratahan↗

DOE OSTI2019

Lipon coatings for high voltage and high temperature Li-ion battery cathodes

36 MATERIALS SCIENCE↗

DOE OSTI2020

Cold cathode switching device and converter

A cold-cathode switching device is presented. The cold-cathode switching device includes a housing defining a chamber; an ionizable gas disposed in the chamber; and a plurality of electrodes disposed in the chamber. The plurality of electrodes includes a cathode and an anode defining a discharge gap, and wherein at least one of the cathode and anode comprises a material that is liquid at an operating temperature of the cathode or the anode.

42 ENGINEERING↗

DOE OSTI2020

Thermionic cathode with a graphene sealing layer and method of making the same

According to an embodiment of the present disclosure, a thermionic cathode includes: a cathode body having an outer surface, and a sealing layer including one or more graphene sheets on the outer surface of the cathode body. According to another embodiment of the present disclosure, a method for manufacturing a thermionic cathode includes: depositing a sealing layer including one or more graphene sheets on an outer surface of a cathode body.

42 ENGINEERING↗

DOE OSTI2020

High capacity and stable cathode materials

High energy density cathode materials, such as LiNixMnyCozO2 (NMC) cathode materials, with improved discharge capacity (hence energy density) and enhanced cycle life are described. A solid electrolyte, such as lithium phosphate infused inside of secondary particles of the cathode material demonstrates significantly enhanced structural integrity without significant or without any observable particle cracking occurring during charge/discharge processes, showing high capacity retention of more than 90% after 200 cycles at room temperature. In certain embodiments the disclosed cathode materials (and cathodes made therefrom) are formed using nickel-rich NMC and/or are used in a battery system with a non-aqueous dual-Li salt electrolytes.

25 ENERGY STORAGE↗

DOE OSTI2023

Oxide mixture and complex oxide coatings for cathode materials

Cathode active materials are provided. The cathode active material can include a plurality of cathode active compound particles. A coating is disposed over each of the cathode active compound particles. The coating can include at least one of ZrO 2 , La 2 O 3 , a mixture of Al 2 O 3 and ZrO 2 or a mixture of Al 2 O 3 and La 2 O 3 . The battery cells that include the cathode active material are also provided.

Wang, Dapeng↗

DOE OSTI2023

Fuel cell cathode and fuel cell system including a polymeric additive

A cathode configured for use within a fuel cell system is provided. The cathode includes a cathode substrate. The cathode further includes a coating disposed upon the cathode substrate and including a fluorocarbon polymer additive configured for sintering at a temperature of less than 200° C. The fluorocarbon polymer additive may be mixed with a catalyst ink coating or may be applied separately as a topcoat layer.

Ramaswamy, Nagappan↗

DOE OSTI2022

Garnet solid electrolyte blended LiNi 0.6 Mn 0.2 Co 0.2 O 2 as high-voltage stable cathodes for advanced lithium-ion batteries

Ni-rich LiNi 1-x Co x/2 Mn x/2 O 2 layered materials have been widely adopted as cathodes for current electric vehicles (EVs) due to their high gravimetric and volumetric energy densities. However, their high-voltage instability (e.g., > 4.3 V vsLi ) limited their usable capacities corresponding to about 60 – 70 % of theoretical capacities. The major problems of high-voltage operation stem from instability of Ni 3+/4+ at cathode-electrolyte interphase (CEI) in contact with electrolytes. Here we propose garnet-type Li 6.7 La 3 Zr 1.7 Ta 0.3 O 12 (LLZT) solid-electrolyte-blended LiNi 0.6 Mn 0.2 Co 0.2 O 2 (NMC) as high-voltage stable cathodes. The LLZT not only passivates the CEI but scavenges protons and moisture in electrolytes. From well-balanced ionic and electronic transport properties, 5 wt% LLZT blended NMC cathodes delivered enhanced electrochemical performances in full-cells. Unlike other complicated coating processes, our proposed solid-electrolyte blending approach can be readily implementable in commercial Li-ion batteries due to its manufacturing friendliness, energy saving, and cost effectiveness.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2020

Correlative electron and ion beam analysis of the electrochemical performances of LiV 3 O 8 cathode films as a function of microstructures

Degradation mechanisms in LiV 3 O 8 cathode films (~500 nm) with different initial microstructures i.e., globular nanocrystals in amorphous matrix and needle-like nanocrystals, synthesized by annealing the cathodes at 150 °C and 300 °C for 6 h are studied by Transmission Electron Microscopy (TEM) and Auger Electron Spectroscopy (AES). In addition, a unique in-situ combination of TEM and Secondary Ion Mass Spectrometry (SIMS) imaging techniques, namely Parallel Ion and Electron beam Spectrometry (PIES) is carried out to measure the 3D distribution of V and Li with nanoscale resolution. These characterization studies focus on correlating the pre- and post-cycling microstructure to observed electrochemical performance. The LiV 3 O 8 cathode film with needle-like nanocrystals (300 °C) shows a higher initial capacity but it degrades rapidly compared to the film with globular nanocrystals embedded in amorphous matrix (150 °C). We observed that LiV 3 O 8 films with needle-like nanocrystals are more susceptible to cathode decohesion and vanadium dissolution than the films with globular nanocrystals embedded in amorphous matrix, explaining the differences in their electrochemical performance. The findings from this study have relevance to the development of thin film electrode microstructures for high capacity and cyclic stability.

25 ENERGY STORAGE↗