Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “cathode loading”

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 253 records · Page 14
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Synergy of Epoxy Chemical Tethers and Defect‐Free Graphene in Enabling Stable Lithium Cycling of Silicon Nanoparticles

Abstract We report a new approach for nanosilicon–graphene hybrids with uniquely stable solid electrolyte interphase. Expanded graphite is gently exfoliated creating “defect‐free” graphene that is non‐catalytic towards electrolyte decomposition, simultaneously introducing high mass loading (48 wt. %) Si nanoparticles. Silane surface treatment creates epoxy chemical tethers, mechanically binding nano‐Si to CMC binder through epoxy ring‐opening reaction while stabilizing the Si surface chemistry. Epoxy‐tethered silicon pristine–graphene hybrid “E‐Si‐pG” exhibits state‐of‐the‐art performance in full battery opposing commercial mass loading (12 mg cm −2 ) LiCoO 2 (LCO) cathode. At 0.4 C, with areal capacity of 1.62 mAh cm −2 and energy of 437 Wh kg −1 , achieving 1.32 mAh cm −2 , 340.4 Wh kg −1 at 1 C. After 150 cycles, it retains 1.25 mAh cm −2 , 306.5 Wh kg −1 . Sputter‐down XPS demonstrates survival of surface C‐Si‐O‐Si groups in E‐Si‐pG after repeated cycling. The discovered synergy between support defects, chemical‐mechanical stabilization of Si surfaces, and SEI‐related failure may become key LIB anode design rule.

Liu, Wei↗
DOE OSTI2023

Scalable Metal Phosphides as a Dual-Function Catalyst and Lithium–Metal Stabilizer for Lithium–Sulfur Batteries

Although lithium-sulfur batteries are a promising approach for achieving high energy density, their commercial viability is limited by poor sulfur redox kinetics, polysulfide shuttling, and lithium metal instability. To resolve these issues concurrently, we utilize titanium phosphides (TiP x ) as dual-function materials to catalyze the sulfur redox kinetics at the cathode and stabilize the lithium metal at the anode. Importantly, these phosphides are synthesized via a facile, highly scalable one-step mechanochemical ball-milling process that does not generate toxic phosphine gas as a byproduct, making it more viable compared to traditional synthesis routes. At the cathode, we find that higher phosphorus contents in the phosphide as in TiP 2 leads to superior redox kinetics and reduced polysulfide shuttling due to improved polysulfide adsorption ability. Meanwhile, at the anode, TiP 2 acts as a lithiophilic seed in a 3-dimensional carbonaceous host that can be lithiated to form a Li-TiP 2 /C composite. This composite alleviates the volume changes of lithium metal while utilizing TiP 2 to form a more favorable solid-electrolyte interface (SEI). Full coin cells employing TiP 2 in the cathode and anode were assembled with a sulfur loading of 4 mg cm -2 and a negative to positive capacity (N/P) ratio of 6. After 50 cycles, the TiP 2 full cells retain a higher capacity of 643 mA h g -1 compared to 422 mA h g -1 for the conventional cell, despite the higher N/P ratio of 12 for the conventional cell. Altogether, we showcase the viability of employing metal phosphides as catalysts in practical lithium-sulfur batteries.

25 ENERGY STORAGE↗
DOE OSTI2025

Stable cycling of high-mass loaded MnO 2 electrodes for sodium-ion batteries

Achieving cost-effective, sustainable solutions for large-scale energy storage are critical for advancing the global clean energy transition. In view of the challenges posed by limited lithium reserves, low-cost sodium-ion batteries (SIBs) have emerged as a promising direction, especially for grid-level energy storage. Among the various battery electrode materials, manganese dioxide (MnO 2 ) stands out as a favorable choice for such large-scale applications due to its earth abundance, cost-effectiveness, and non-toxic nature. Although MnO 2 is known as a pseudocapacitive material with superior cycling stability in aqueous electrolytes, its dissolution in non-aqueous electrolytes has restricted its use in long-lifetime batteries. In this study, we address two issues which have limited the use of MnO 2 electrodes in non-aqueous electrolytes. First, using electrochemical quartz crystal microbalance measurements in combination with other electrochemical methods, we demonstrate that diglyme (bis(2-methoxyethyl) ether) electrolyte can achieve stable cycling of electrodeposited ε-MnO 2 . These results enable us to tackle a second objective, that is increasing the mass loading of the MnO 2 electrode, since achieving high areal energy density is a significant factor in reducing manufacturing costs. Using 3D printed graphene aerogel (GA) as a scaffold, our studies show that the electrodeposited MnO 2 /GA electrodes possess scalable properties with mass loadings from 20 to 80 mg cm −2 . The resulting electrodes exhibit areal energy densities as high as 4.4 mA h cm −2 at a current density of 10 mA cm −2 . The high mass loaded MnO 2 electrodes were incorporated as a cathode in a SIB which used TiO 2 as the anode. The SIB device exhibited excellent performance with power densities in excess of 70 mW cm −2 . These studies highlight the promise of MnO 2 electrodes for use in a low-cost technology for large-scale energy storage.

25 ENERGY STORAGE↗
DOE OSTI2023

Rational designs to enable 10-min fast charging and long cycle life in lithium-ion batteries

A daunting challenge in the design of lithium ion batteries (LiBs) is enabling 10-min extreme fast charging (XFC) while achieving appreciable charge acceptance and cycle life. This desirable outcome requires both a comprehensive understanding of LiB operation and aging behavior at different length scales and careful optimization. Lithium plating has been a critical bottleneck because, at XFC rates, it consumes cyclable lithium causing distinct aging and safety concerns even in moderate-loading LiBs. Here, we propose combining multiple solutions, including materials-to-electrode design-to-charging protocols, that are intended to overcome limitations in lithium-ion transport in the electrolyte phase, thus enabling 10-min XFC in LiBs. Some implemented strategies include cathode chemistry, optimized carbon binder domain in the cathode, dual layer anode design, improved separator and advanced electrolyte. Further, innovative charging protocols in moderately loading (~3 mAh/cm 2 anode/2.7 mAh/cm 2 cathode) single-layer pouch cells are proposed, together with demonstrated 10-min XFC with higher charge acceptance between 87.3 and 92.1% (or 2–2.1 mAh/cm 2 ) for 600 cycles without lithium plating. This methodical study with well-defined cells shows promise in combining multiple solution strategies to enable 10-min XFC, charting a pathway to achieve XFC in higher-loading energy-optimized LiBs.

25 ENERGY STORAGE↗
DOE OSTI2017

Battery anode with preloaded metals

A method is presented for fabricating an anode preloaded with consumable metals. The method provides a material (X), which may be one of the following materials: carbon, metals able to be electrochemically alloyed with a metal (Me), intercalation oxides, electrochemically active organic compounds, and combinations of the above-listed materials. The method loads the metal (Me) into the material (X). Typically, Me is an alkali metal, alkaline earth metal, or a combination of the two. As a result, the method forms a preloaded anode comprising Me/X for use in a battery comprising a M1YM2Z(CN)N.MH2O cathode, where M1 and M2 are transition metals. The method loads the metal (Me) into the material (X) using physical (mechanical) mixing, a chemical reaction, or an electrochemical reaction. Also provided is preloaded anode, preloaded with consumable metals.

36 MATERIALS SCIENCE↗
DOE OSTI2017

Communication—Analysis of Thick Co-Extruded Cathodes for Higher-Energy-and-Power Lithium-Ion Batteries

3-dimensional (3D) electrode architectures have been explored as a means to decouple power and energy trade-offs in thick battery electrodes. Limited work has been published which systematically examines the impact of these architectures at the pouch cell level. This paper conducts an analysis on the potential capacity gains that can be realized with thick co-extruded electrodes in a pouch cell. Moreover, our findings show that despite lower active material composition for each cathode layer, the effective gain in thickness and active material loading enables pouch cell capacity gains greater than 10% with a Lithium Nickel Manganese Cobalt Oxide (NMC) materials system.

25 ENERGY STORAGE↗
DOE OSTI2021

The Impact of Anomalous Resistivity in Vacuum Contaminant Plasmas on the Electrothermal Instability

This manuscript presents an assessment of the electrothermal instability (ETI) in the presence of anomalous resistivity (AR) in vacuum contaminant plasmas (VCP) when applied to a magnetized liner inertial fusion (MagLIF)-like load.Pulsed-power driven dielectrically coated metallic liners, like in MagLIF, experience the current-driven electrothermal instability which occurs when a material’s resistivity changes with temperature and is subject to ohmic heating. Large scale pulsed-power facilities that use magnetically insulated transmission lines (MITL) have been shown to generate low-density plasma which enters the target chamber and coalesces around the load. The low-density high-temperature vacuum contaminant plasmas (VCP) can parasitically divert current from the load through causing a short in the anode-cathode gap inside the target chamber. Resistive magnetohydrodynamic (MHD) simulations of these VCP experience unphysical runaway ohmic heating due to under predicting the resistivity by using a purely collisional resistivity model.AR provides a physics-based way to address this runaway heating through increasing the resistivity in a proportional way with the drift speed. In this work, 1D simulations probe the effect that AR in VCP has on the magnetic diffusion rate, and 2D simulations show how this effect manifests in the nonlinear striation form of the ETI for a MagLIF-like load. Beryllium and aluminum dielectrically coated liners are used for the 1D and 2D simulations in this work. The1D simulations show that a VCP causes a delay in the current delivery to the load by upwards of 8 ns at 60 ns into atypical current pulse for an 1 × 10 7 A scale pulsed-power accelerator. The 2D simulations show the delay observed in the 1D simulations is reduced substantially (4 ns) by 2D turbulence that disrupts the VCP layer early in time. Here, the 2Dsimulated ETI growth varies across AR models, more so for the beryllium liner than the aluminum liner because the beryllium liner shows an enhanced rate of penetration for the magnetic diffusion wave in comparison to the aluminum liner. The 2D simulations show the bulk dielectric thickness varies across AR models with the Davidson AR model beingthe largest and the Buneman AR model being the smallest, and in connection with the thickness the Rayleigh-Taylor bubble-spike distances varies correspondingly.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2026

Impact of Porous Transport Layer Morphology on the Performance of Proton Exchange Membrane Water Electrolyzers with Ultra-Low Iridium Loadings

Reducing Ir loadings in proton exchange membrane water electrolyzer anodes is critical for lowering capital expenses. Loading reduction could be achieved by improving the Ir activity via doping/alloying and/or the development of advanced microstructures. However, the anode porous transport layer (PTL) is a comparatively simple component whose properties also impact Ir utilization. Therefore, well-designed PTLs may also enable reduced Ir loadings. In this work, we survey eight PTLs from various manufacturers to observe their impact on cell performance at low (0.4 mg Ir cm -2 ) and ultralow (0.1 mg Ir cm -2 ) Ir loadings. The PTLs were characterized by their microstructural properties, including porosity, particle size distribution, and pore size distribution. Electrochemical cell performance was correlated to PTL morphology, and it was found that PTLs with lower porosities and smaller particle and pore radii enabled good performance even at ultralow Ir loadings. 1000-h durability testing indicated that using lower porosity PTLs can significantly improve durability behavior. A runaway voltage phenomenon was observed during durability testing of cells with ultralow Ir loadings, which was caused by increases in both anode and cathode overpotentials. Furthermore, we observed that the beginning of test performance of 0.1 mg Ir cm -2 cells correlates to the 1000-h degradation rates of 0.4 mg Ir cm -2 cells, suggesting that for the Ir catalyst used in this work, short-term testing at ultralow loadings can be used as an indicator of long-term degradation at higher loadings.

08 HYDROGEN↗
DOE OSTI2019

Cathode porosity is a missing key parameter to optimize lithium-sulfur battery energy density

While high sulfur loading has been pursued as a key parameter to build realistic high-energy lithium-sulfur batteries, less attention has been paid to the cathode porosity, which is much higher in sulfur/carbon composite cathodes than in traditional lithium-ion battery electrodes. For high-energy lithium-sulfur batteries, a dense electrode with low porosity is desired to minimize electrolyte intake, parasitic weight, and cost. Here we report the profound impact on the discharge polarization, reversible capacity, and cell cycling life of lithium-sulfur batteries by decreasing cathode porosities from 70 to 40%. According to the developed mechanism-based analytical model, we demonstrate that sulfur utilization is limited by the solubility of lithium-polysulfides and further conversion from lithium-polysulfides to Li2S is limited by the electronically accessible surface area of the carbon matrix. Finally, we predict an optimized cathode porosity to maximize the cell level volumetric energy density without sacrificing the sulfur utilization.

25 ENERGY STORAGE↗
DOE OSTI2017

Development of High Power Density Metal‐Supported Solid Oxide Fuel Cells

Abstract Symmetric‐structure metal‐supported solid oxide fuel cells (MS‐SOFCs) are fabricated by infiltrating catalysts on both anode and cathode side. Various aspects of the infiltration process are optimized. Performance is found to be sensitive to precursor dilution, catalyst loading, and catalyst calcining temperature. For an optimized cell with lanthanum strontium manganite (LSM) as cathode and Sm 0.2 Ce 0.8 O 2− δ mixed with Ni (SDCN) as anode, peak power densities of 0.44, 1.1, and 1.9 W cm −2 are achieved at 600, 700, and 800 °C, respectively. A fully symmetric MS‐SOFC with SDCN as both the anode and cathode sides achieves moderate peak power densities of 0.12, 0.37, and 0.76 W cm −2 at 600, 700, and 800 °C, respectively. A solvent‐based infiltration technique is also explored and found to be more effective than capillary forces alone but not as effective as vacuum infiltration.

Tucker, Michael C.↗
DOE OSTI2024

Freeze Tape Casting Electrode with Bilayered Architecture for High-Performance Lithium-Ion Batteries

A facile freeze tape casting (FTC) strategy is utilized to prepare bilayered 4 mAh cm –2 high-loading LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathodes. The bottom layer is a conventional nonaqueous electrode, which has a dense structure for high-energy purposes. Further, the top layer is prepared by the proposed FTC, exhibiting a porous feature for high-power requirement. With the assistance of FTC, the bilayered electrodes successfully deliver enhanced rate and cyclic performance due to the improved lithium-ion diffusion kinetics and pathways. Therefore, the proposed FTC strategy and its delivered electrodes are promising for energy- and power-density lithium-ion batteries, potentially enlightening the research and development of lithium-ion battery manufacturing.

25 ENERGY STORAGE↗
DOE OSTI2016

Implosion dynamics of a megampere wire-array Z-pinch with an inner low-density foam shell at the Angara-5-1 facility

The implosion dynamics of a pinch with a highly inhomogeneous initial axial distribution of the load mass was studied experimentally. A cascade array consisting of a double nested tungsten wire array and a coaxial inner cylindrical shell located symmetrically with respect to the high-voltage electrodes was used as a load of the Angara-5-1 high-current generator. The cylindrical foam shell was half as long as the cathode− anode gap, and its diameter was equal to the diameter of the inner wire array. It is shown experimentally that two stages are typical of the implosion dynamics of such a load: the formation of two separate pinches formed as a result of implosion of the wire array near the cathode and anode and the subsequent implosion of the central part of the load containing the cylindrical foam shell. The conditions are determined at which the implosion of the central part of the pinch with the foam cylinder is preceded by intense irradiation of the foam with the soft X-ray (SXR) emission generated by the near-electrode pinches and converting it into the plasma state. Using such a load, which models the main elements of the scheme of a dynamic hohlraum for inertial confinement fusion, it is possible to increase the efficiency of interaction between the outer accelerated plasma sheath and the inner foam shell by preionizing the foam with the SXR emission of the near-electrode pinches.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Nitrogen‐doped Carbon–CoO x Nanohybrids: A Precious Metal Free Cathode that Exceeds 1.0 W cm −2 Peak Power and 100 h Life in Anion‐Exchange Membrane Fuel Cells

Abstract Efficient and durable nonprecious metal electrocatalysts for the oxygen reduction (ORR) are highly desirable for several electrochemical devices, including anion exchange membrane fuel cells (AEMFCs). Here, a 2D planar electrocatalyst with CoO x embedded in nitrogen‐doped graphitic carbon (N‐C‐CoO x ) was created through the direct pyrolysis of a metal–organic complex with a NaCl template. The N‐C‐CoO x catalyst showed high ORR activity, indicated by excellent half‐wave (0.84 V vs. RHE) and onset (1.01 V vs. RHE) potentials. This high intrinsic activity was also observed in operating AEMFCs where the kinetic current was 100 mA cm −2 at 0.85 V. When paired with a radiation‐grafted ETFE powder ionomer, the N‐C‐CoO x AEMFC cathode was able to achieve extremely high peak power density (1.05 W cm −2 ) and mass transport limited current (3 A cm −2 ) for a precious metal free electrode. The N‐C‐CoO x cathode also showed good stability over 100 hours of operation with a voltage decay of only 15 % at 600 mA cm −2 under H 2 /air (CO 2 ‐free) reacting gas feeds. The N‐C‐CoO x cathode catalyst was also paired with a very low loading PtRu/C anode catalyst, to create AEMFCs with a total PGM loading of only 0.10 mg Pt‐Ru cm −2 capable of achieving 7.4 W mg −1 PGM as well as supporting a current of 0.7 A cm −2 at 0.6 V with H 2 /air (CO 2 free)—creating a cell that was able to meet the 2019 U.S. Department of Energy initial performance target of 0.6 V at 0.6 A cm −2 under H 2 /air with a PGM loading <0.125 mg cm −2 with AEMFCs for the first time.

Peng, Xiong↗
DOE OSTI2018

Nitrogen‐doped Carbon–CoO x Nanohybrids: A Precious Metal Free Cathode that Exceeds 1.0 W cm −2 Peak Power and 100 h Life in Anion‐Exchange Membrane Fuel Cells

Abstract Efficient and durable nonprecious metal electrocatalysts for the oxygen reduction (ORR) are highly desirable for several electrochemical devices, including anion exchange membrane fuel cells (AEMFCs). Here, a 2D planar electrocatalyst with CoO x embedded in nitrogen‐doped graphitic carbon (N‐C‐CoO x ) was created through the direct pyrolysis of a metal–organic complex with a NaCl template. The N‐C‐CoO x catalyst showed high ORR activity, indicated by excellent half‐wave (0.84 V vs. RHE) and onset (1.01 V vs. RHE) potentials. This high intrinsic activity was also observed in operating AEMFCs where the kinetic current was 100 mA cm −2 at 0.85 V. When paired with a radiation‐grafted ETFE powder ionomer, the N‐C‐CoO x AEMFC cathode was able to achieve extremely high peak power density (1.05 W cm −2 ) and mass transport limited current (3 A cm −2 ) for a precious metal free electrode. The N‐C‐CoO x cathode also showed good stability over 100 hours of operation with a voltage decay of only 15 % at 600 mA cm −2 under H 2 /air (CO 2 ‐free) reacting gas feeds. The N‐C‐CoO x cathode catalyst was also paired with a very low loading PtRu/C anode catalyst, to create AEMFCs with a total PGM loading of only 0.10 mg Pt‐Ru cm −2 capable of achieving 7.4 W mg −1 PGM as well as supporting a current of 0.7 A cm −2 at 0.6 V with H 2 /air (CO 2 free)—creating a cell that was able to meet the 2019 U.S. Department of Energy initial performance target of 0.6 V at 0.6 A cm −2 under H 2 /air with a PGM loading <0.125 mg cm −2 with AEMFCs for the first time.

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

A Novel Multiagent Resource Sharing Algorithm for Control of Advanced Energy Systems

This paper implements a novel resource sharing control strategy on a fuel cell–gas turbine hybrid power system at the National Energy Technology Laboratory’s Hybrid Performance Facility (Hyper). In a fuel cell–gas turbine hybrid power system, the simultaneous interaction of the gas turbine and the fuel cell creates a tightly coupled environment characterized by conflicting dynamics. In this paper, a model-free control approach is applied to solve the tightly coupled control problem posed by this challenging environment. Specifically, this control problem is presented as a resource sharing problem that can be solved using a resource sharing algorithm that is defined based on the distribution construction concept. This algorithm creates computational agents and solves the problem through the distribution and redistribution of shared resources defined as blocks. Furthermore, two agents were created; the first agent (agent 1) controls the gas turbine speed by adjusting the electric load, and the second agent (agent 2) controls the cathode mass flow through the fuel cell using the cold-air bypass valve. A parametric study was performed over the course of 15 experimental tests for both agents 1 and 2 through an evaluation of the responses based on setpoint changes. The algorithm was shown to have behavior comparable to a previously implemented multi-input multioutput state-space controller, which was designed through a model-based control approach. The resource sharing algorithm was able to find stable performance during run-time operations without any prior system knowledge identification on the power plant and without creating models used in traditional control strategies.

25 ENERGY STORAGE↗
DOE OSTI2019

Electrocatalytic Hydrogen Evolution in Neutral pH Solutions: Dual-Phase Synergy

Electrolysis in neutral pH solutions (e.g., wastewater and seawater) presents a transformative way for environmentally friendly, cost-effective hydrogen production. However, one of the biggest challenges is the lack of active, robust hydrogen evolution reaction (HER) catalysts. Herein we present a catalyst with dual active sites of MoP2 and MoP which function synergistically to promote HER in neutral pH solutions. In our microbial electrolysis cell (MEC) which uses neutral pH wastewater as a feedstock, the new catalyst generates an average HER current density of ~157 A m-2Cathode-Surface-Area, higher than Pt/C (~145 A m-2Cathode-Surface-Area), ~5 times higher than the state-of-art platinum-group-metal (PGM)-free catalysts in MECs. The new catalyst also outperforms Pt/C in natural seawater with ~10% higher and more stable HER current density. The fundamental reason for the enhanced HER performance is identified to be the synergy between MoP2 and MoP phases, with MoP2 promoting H2O chemisorption/dissociation and MoP efficiently converting Hads to H2.

Xie, Xiaohong↗
DOE OSTI2013

In Situ Foaming of Porous (La 0.6 Sr 0.4 ) 0.98 (Co 0.2 Fe 0.8 ) O 3-δ (LSCF) Cathodes for Solid Oxide Fuel Cell Applications

A binder system containing polyurethane precursors was used to in situ foam (direct foam) a (La{sub 0.6}Sr{sub 0.4}){sub 0.98} (Co{sub 0.2} Fe{sub 0.8}) O{sub 3-{ delta}} (LSCF) composition for solid oxide fuel cell (SOFC) cathode applications. The relation between in situ foaming parameters on the final microstructure and electrochemical properties was characterized by microscopy and electrochemical impedance spectroscopy (EIS), respectively. The optimal porous cathode architecture was formed with a 70 vol% solids loading within a polymer precursor composition with a volume ratio of 8:4:1 (isocyanate: PEG: surfactant) in a terpineol-based ink vehicle. The resultant microstructure displayed a broad pore size distribution with highly elongated pore structure.

30 DIRECT ENERGY CONVERSION↗