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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Long-Life Lithium-Sulfur Batteries with a Bifunctional Cathode Substrate Configured with Boron Carbide Nanowires

Developing high-energy-density lithium–sulfur (Li–S) batteries relies on the design of electrode substrates that can host a high sulfur loading and still attain high electrochemical utilization. Herein, a new bifunctional cathode substrate configured with boron-carbide nanowires in situ grown on carbon nanofibers (B 4 C@CNF) is established through a facile catalyst-assisted process. The B 4 C nanowires acting as chemical-anchoring centers provide strong polysulfide adsorptivity, as validated by experimental data and first-principle calculations. Meanwhile, the catalytic effect of B 4 C also accelerates the redox kinetics of polysulfide conversion, contributing to enhanced rate capability. As a result, a remarkable capacity retention of 80% after 500 cycles as well as stable cyclability at 4C rate is accomplished with the cells employing B 4 C@CNF as a cathode substrate for sulfur. Moreover, the B 4 C@CNF substrate enables the cathode to achieve both high sulfur content (70 wt%) and sulfur loading (10.3 mg cm -2 ), delivering a superb areal capacity of 9 mAh cm -2 . In addition, Li–S pouch cells fabricated with the B 4 C@CNF substrate are able to host a high sulfur mass of 200 mg per cathode and deliver a high discharge capacity of 125 mAh after 50 cycles.

25 ENERGY STORAGE↗
DOE OSTI2026

CoEx Electrode Structuring for High Energy and Fast Charging Lithium-Ion Batteries

This project was a collaboration between SRI International (SRI) and Oak Ridge National Laboratory (ORNL) focused on advancing SRI’s CoEx technology for printing of battery electrodes with structured porosity, specifically for improving fast charging performance. Prior work funded by the Vehicle Technologies Office (VTO) served as proof-of-concept for CoEx printing, with the scope limited to demonstrating that CoEx structuring in the cathode would improve discharge performance. In that work, a thick cathode was paired with an anode produced through conventional means (i.e. it had no structuring), and the baseline comparison was a cell with conventionally produced cathode and anode of similar loading, along with a lower loaded cell that was intended to represent cells of typical loading. The result of that work showed that the CoEx cells had higher energy density than the thin baseline cells, due to the thicker electrode layers, and had much higher power density than the thick baseline cells at higher discharge rates, because the CoEx cathode had higher performance than the conventional cathode. In this project, we proposed to extend the CoEx technology to structure both the anode and cathode of a lithium ion battery, resulting in at least a 20% increase in energy density under fast charging conditions, while reducing costs by 15% and cutting energy usage during production.

25 ENERGY STORAGE↗
DOE OSTI2016

Investigation of a microporous iron( III ) porphyrin framework derived cathode catalyst in PEM fuel cells

In Polymer Electrolyte Membrane Fuel Cells (PEMFCs) the thickness, structure and morphology of the electrode layer play an important role in the cell performance. This effect becomes particularly significant when the cathode catalyst is based on a non-precious metal due to the higher catalyst loadings required to compensate for the lower catalytic activity when compared to Pt based catalysts. In this study, an iron( III ) porphyrin framework material was synthesized and pyrolyzed and its catalytic activity towards the oxygen reduction reaction (ORR) was evaluated using rotating disk electrode (RDE) experiments and single cell testing. Single cell performance was evaluated as a function of the electrode catalyst loading (electrode thickness) and oxygen partial pressure. As expected, the ORR kinetic overpotential was the major contributor to the overall voltage loss. However, the mass transport contribution to the voltage loss became more prominent with small increases in the cathode catalyst loading. Finally, the observed performance is discussed in the context of structure and morphology of the catalyst layer (CL), analyzed through scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD).

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2018

Hydrogen production from pine-derived catalytic pyrolysis aqueous phase via microbial electrolysis

In this paper, microbial electrolysis of an aqueous phase generated from catalytic pyrolysis of pine sawdust was investigated for renewable hydrogen production. The microbial electrolysis cell (MEC) performance was investigated at an organic loading rate ranging from 2 to 50 g/L-day. A maximum hydrogen productivity of 5.8 ± 0.18 L/L-day was obtained, however, the productivity increased linearly only up to a loading rate of 10 g/L-day. The highest current density achieved was 6.8 ± 0.1 A/m 2 . The efficiency of conversion of the substrate to current in the anode decreased with increasing loading, but the initial maximum Coulombic efficiency was 98 ± 0.04%. The cathode efficiency, on the other hand, increased with loading up to a maximum of 89 ± 1.4%. Total hydrogen recovery was relatively constant for most runs at 30%, which is equivalent to an yield of 0.6 moL H 2 /mole COD, except at the highest loading rate. The operation of the MEC under batch mode, however, resulted in a higher hydrogen recovery of 63 ± 4%. The conversion of a wide range of compounds, including carboxylic acids, anhydrosugars, furanic and phenolic compounds present in the aqueous phase is reported. Finally, the results demonstrate potential for hydrogen production from a waste stream which can improve the total biofuel or energy yield of the biorefinery.

08 HYDROGEN↗
DOE OSTI2022

Impact of power flow on Z-pinch loads

Magnetically insulated transmission lines (MITLs) are used to deliver tens of MA to a Z-pinch load. The MITLs suffer current losses due to contaminant plasma located in the anode–cathode gap which is swept toward the load along the power flow. The swept up contaminant plasma can deposit mass and energy onto the load resulting in deformations or the seeding of macroscopic instabilities. This paper discusses 2D fully kinetic simulations of the contaminant plasma evolution which predict the current losses and the flux of mass and energy onto the load. Furthermore, the effects of a dynamic, i.e., imploding, load are shown to increase both the current loss and the mass and energy flux. The MITL used is a conical, radially converging design which is a feature common to MA-scale Z-pinch accelerators.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

Super p-sulfur cathodes for quasi-solid-state lithium-sulfur-batteries

Lithium-Sulfur (Li-S) batteries have become a promising candidate to meet the current energy storage demand, with its natural abundance of materials, high theoretical capacity of 1672 mAhg-1, high energy density of 2600 Whkg-1, low cost and lower environmental impact. Sulfide based solid state electrolytes (SSEs) have received greater attention due to their higher ionic conductivity, compatible interface with sulfur-based cathodes, and lower grain boundary resistance. However, the interface between SSEs and cathodes has become a challenge in all solid-state Li-S batteries due to the rigidity of the participating surfaces. A hybrid electrolyte containing SSE coupled with a small amount of ionic liquid, was essential to improve the interface contact of the SSE with the electrodes. Coating-based cathodes were successfully fabricated using water-based carboxymethyl cellulose (CMC) solution and Styrene butadiene rubber (SBR) as the binder with low sulfur loading (0.70 mgcm-2) as well as high sulfur loading (4.0 mgcm-2). Solid-state composite powder-based cathodes pressed onto SSE (loading 4.0 mgcm-2) with enhanced electronic and ionic conductivity were fabricated with Super P: Sulfur (SP:S) and SSE. Ionic Liquids (IL) prepared using Lithium bis(trifluoromethyl sulfonyl)imide (LiTFSI) as salt, with premixed pyrrolidinium bis(trifluoromethyl sulfonyl)imide (PYR) as solvent and 1,3-dioxolane (DOL) as diluent were used to wet both SSE-electrode interfaces. The effect of IL dilution, co-solvent amount, LiTFSI concentration, C rate at which the batteries are tested and the effect of SSE inside the cathode, were systematically studied and optimized to develop a quasi-solid-state electrolyte Li-S battery (QSSLSB) with higher capacity retention and cyclability. LiTFSI (2M) dissolved in PYR:DOL(1:1) found to be optimum IL combination for low sulfur loading QSSLSBs reaching 500 mAh/g after 100 cycles while LiTFSI (3M) in PYR:DOL(1:3) was the optimum IL concentration for higher loading QSSLSBs reaching 400 mAh/g after 100 cycles. This work reports promising results of QSSLSB based on novel Li6PS5F0.5Cl0.5 Li-argyrodite solid-state electrolyte (SSE) with minute amount of IL, Super P-Sulfur (SP:S) cathode, and Li-anode. It also offers a new insight into the intimate interfacial contacts between the SSE and carbon-sulfur cathodes, which will be critical for improved electrochemical performance of quasi-solid-state lithium-sulfur batteries with high sulfur loading in the future.

25 ENERGY STORAGE↗
DOE OSTI2017

Rational Design of Statically and Dynamically Stable Lithium-Sulfur Batteries with High Sulfur Loading and Low Electrolyte/Sulfur Ratio

Here, the primary challenge with lithium–sulfur battery research is the design of sulfur cathodes that exhibit high electrochemical efficiency and stability while keeping the sulfur content and loading high and the electrolyte/sulfur ratio low. With a systematic investigation, a novel graphene/cotton–carbon cathode is presented here that enables sulfur loading and content as high as 46 mg cm –2 and 70 wt% with an electrolyte/sulfur ratio of as low as only 5. The graphene/cotton–carbon cathodes deliver peak capacities of 926 and 765 mA h g –1 , respectively, at C/10 and C/5 rates, which translate into high areal, gravimetric, and volumetric capacities of, respectively, 43 and 35 mA h cm –2 , 648 and 536 mA h g –1 , and 1067 and 881 mA h cm –3 with a stable cyclability. They also exhibit superior cell–storage capability with 95% capacity–retention, a low self–discharge constant of just 0.0012 per day, and stable poststorage cyclability after storing over a long period of six months. Here, this work demonstrates a viable approach to develop lithium–sulfur batteries with practical energy densities exceeding that of lithium–ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2026

Cathode-Confined Polysulfide Retention-Release Reprograms Li 2 S Deposition in High-Loading Li–S Batteries

High-loading lithium-sulfur (Li-S) cells operated with lean electrolyte are limited by polysulfide crossover to Li metal and by transport-limited liquid-solid conversion that forms passivating Li 2 S films. Here, we show that a cathode-facing separator coating of carboxylated multiwalled carbon nanotubes acts as a cathode-confined polysulfide reservoir with intermediate binding. Early in discharge it captures newly generated polysulfides at the separator interface, suppressing shuttle reactions. As polysulfides are consumed, the reservoir buffers concentration gradients and feeds reactants back to the cathode, shifting Li 2 S deposition from burst-like film growth to progressive, three-dimensional, porous formation. Synchrotron XRD and S K-edge XANES, together with Scharifker–Hills nucleation analysis and depth-of-discharge EIS/DRT, substantiate this coupled transport–reaction control. With 4.3 mg S cm -2 and E/S = 5, cells reach 4.2 mAh cm -2 and retain 90% capacity over 100 cycles at 20 °C.

25 ENERGY STORAGE↗
DOE OSTI2020

Revisiting the Role of Conductivity and Polarity of Host Materials for Long-Life Lithium–Sulfur Battery

Despite their high theoretical energy density and low cost, lithium-sulfur batteries (LSBs) suffer from poor cycle life and low energy efficiency owing to the polysulfides shuttle and the electronic insulating nature of sulfur. Conductivity and polarity are two critical parameters for the search of optimal sulfur host materials. However, their role in immobilizing polysulfides and enhancing redox kinetics for long-life LSBs are not fully understood. In this work we have conducted an evaluation on the role of polarity over conductivity by using a polar but nonconductive platelet ordered mesoporous silica (pOMS) and its replica platelet ordered mesoporous carbon (pOMC), which is conductive but nonpolar. It is found that the polar pOMS/S cathode with a sulfur mass fraction of 80 wt% demonstrates outstanding long-term cycle stability for 2000 cycles even at a high current density of 2C. Furthermore, the pOMS/S cathode with a high sulfur loading of 6.5 mg cm -2 illustrates high areal and volumetric capacities with high capacity retention. Complementary physical and electrochemical probes clearly show that surface polarity and structure are more dominant factors for sulfur utilization efficiency and long-life, while the conductivity can be compensated by the conductive agent involved as a required electrode material during electrode preparation. The present findings shed new light on the design principles of sulfur hosts towards long-life and highly efficient LSBs.

25 ENERGY STORAGE↗
DOE OSTI2018

Cobalt nanoparticle-encapsulated carbon nanowire arrays: Enabling the fast redox reaction kinetics of lithium-sulfur batteries

The commercial application of lithium-sulfur batteries is still impeded by the unsatisfying cyclability due to the sluggish reaction kinetics and shuttling effect of polysulfide intermediates. We develop a cobalt nanoparticle-encapsulated carbon nanowire arrays on carbon cloth (CC@Co-CNAs) to enable the fast redox reaction kinetics of the lithium sulfur batteries. The nanowire array-decorated carbon cloth as conductive matrix for sulfur active material could provide highly exposed cobalt nanoparticle active sites, owing to the high length-diameter ratio of the prepared CC@Co-CNAs. The binding affinity between the cobalt nanoparticle-incorporated materials and polysulfide intermediates is enhanced by Co-S bonds, which facilitates the redox reaction of active materials and consequently results in a high sulfur utilization for cathode especially with high sulfur loading. The lithium sulfur battery with CC@Co-CNAs as electrode materials delivers a high initial discharge capacity of 1228 mAh g –1 at 0.25 C, and a high initial discharge capacity of 807 mAh g –1 at 1C with a low capacity fading rate of 0.06% per cycle during 300 cycles. Furthermore, a discharge capacity of 958 mAhg –1 at 0.1 C is achieved for the cell even with a corresponding sulfur loading of 6.2 mg cm –2 .

25 ENERGY STORAGE↗
DOE OSTI2018

Palladium nanocrystals-imbedded mesoporous hollow carbon spheres with enhanced electrochemical kinetics for high performance lithium sulfur batteries

Lithium sulfur (Li-S) battery is one promising candidate for high energy density electrochemical energy storage system. Accelerating the sluggish reaction kinetics of sulfur cathode and suppressing the lithium polysulfide (LiPS) shuttle are crucial for the high-performance Li-S batteries. Herein, we prepared the catalytic palladium nano-particles (Pd NPs) imbedded in hollow carbon spheres (Pd@HCS) as sulfur host by a sacrificial template method. Benefitting from the hollow nanostructure and strong chemisorption ability of Pd NPs, Pd@HCS can effectively mitigate the LiPS shuttling via physical and chemical pathways. Furthermore, the Pd NPs as one electrocatalyst can accelerate the redox reaction kinetics of LiPS. The theoretical calculation and X-ray absorption spectroscopy elucidate that the moderate Pd-S bonding between Pd NPs and sulfur species are beneficial to LiPS conversion. The Pd@HCS/S electrode delivers a high initial capacity of 1306 mAh g –1 and 885 mAh g –1 after 100 cycles at 0.2 C, as well as the good cycling stability (a slight capacity decay of 0.068% per cycle over 400 cycles at 1 C). In conclusion, the Pd@HCS/S cathode with the high sulfur loading of 5.88 mg cm –2 delivers an initial capacity of 873 mAh g –1 at 0.2 C and good capacity retention of 85% after 100 cycles.

25 ENERGY STORAGE↗
DOE OSTI2024

Li 2.9 Fe 0.9 Zr 0.1 Cl 6 as Redox-Active Catholyte for Solid-State Li-Ion Batteries

Solid electrolytes are one of the key challenges that hinder the commercialization of all-solid-state batteries. Most efforts have been made to advance the development of solid electrolytes as separators, while the development of catholytes, particularly redox-active catholytes, has been less extensively studied. The high loading of catholytes in composite cathodes, while facilitating ionic conduction, drastically decreases the energy density of the battery. Here, we report an alternative strategy to improve the energy density by using Li 2.9 Fe 0.9 Zr 0.1 Cl 6 as a redox-active catholyte. With a composite cathode containing uncoated LiCoO2 and Li 2.9 Fe 0.9 Zr 0.1 Cl 6 , the solid-state cell not only shows excellent rate capability and stable long-term cycling, benefiting from the high ionic conductivity of Li 2.9 Fe 0.9 Zr 0.1 Cl 6 , but also shows a high cathode specific capacity of ~153 mAh·g –1 . This study broadens the chemical space of the materials design for lithium-ion conductors with redox-active elements (e.g., Fe, Ti, V, and Cr), offering new opportunities to reduce the cost and improve the energy density for all-solid-state batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2021

High-performing commercial Fe–N–C cathode electrocatalyst for anion-exchange membrane fuel cells

Here, to reduce the cost of fuel cell stacks and systems, it is important to create commercial catalysts that are free of platinum group metals (PGMs). To do this, such catalysts must have very high activity, but also have the correct microstructure to facilitate the transport of reactants and products. Here, we show a high-performing commercial oxygen reduction catalyst that was specifically developed for operation in alkaline media and is demonstrated in the cathode of operating anion-exchange membrane fuel cells (AEMFCs). With H 2 /O 2 reacting gases, AEMFCs made with Fe–N–C cathodes achieved a peak power density exceeding 2 W cm –2 (>1 W cm –2 with H 2 /air) and operated with very good voltage durability for more than 150 h. These AEMFCs also realized an iR-corrected current density at 0.9 V of 100 mA cm –2 . Finally, in a second configuration, Fe–N–C cathodes paired with low-loading PtRu/C anodes (0.125 mg PtRu per cm 2 , 0.08 mg Pt per cm 2 ) demonstrated a specific power of 10.4 W per mg PGM (16.25 W per mg Pt).

25 ENERGY STORAGE↗
DOE OSTI2023

Hot Pressing of Reinforced Li-NMC All-Solid State Batteries with Sulfide Glass Electrolyte

The performance of solid-state batteries (SSBs) with sulfide solid-state electrolytes (SSEs) is limited because they are 10 - 30% porous. Porosity limits energy density of the composite cathode and provides a conduit for Li-metal deposits through the separator if operating specifications (e.g. current density, operating temperature, and pressure) are not strictly controlled. This project focused on demonstrating that hot press cell processing and appropriately formulated sulfide glass SSEs can help eliminate porosity to enable SSBs with energy density of ≥ 350 Wh/kg. The objective of the project was to research, develop, and test SSBs capable of achieving program performance metrics by implementing appropriately formulated sulfide glass SSEs and hot press cell processing in a dry room environment. In the composite cathode, hot pressing helps eliminate porosity to increase energy density by enabling thick composite cathodes with high active material loading. In the separator, hot pressing helps eliminate porosity that may otherwise provide a conduit for Li metal deposits to short the cell.

25 ENERGY STORAGE↗
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 OSTI2016

Communication—Improving Intermediate-Temperature Performance of a Screen-Printed LSCF Cathode with Infiltrated LSCF Nanoparticles

Here, the present study investigates the mass loading effect of an infiltrated La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) nanoparticles (NPs) catalyst on the area-specific polarization resistance (Rp) of a screen-printed porous LSCF cathode for solid oxide fuel cells. The results show that R p of the LSCF-NPs decorated LSCF cathode can be substantially reduced by as much as 89.3% after a single-step impregnation of 1.5 M nitrate solution containing La:Sr:Co:Fe = 0.6:0.4:0.2:0.8 with a mass loading of 3 wt%.

25 ENERGY STORAGE↗
DOE OSTI2022

Durable High-Power Membrane Electrode Assemblies with Low Pt Loading

Recent progress in developing and implementing Pt-alloy cathode catalysts and thin (10-15 micron) low resistance membranes has enabled high performance state of art (SOA) membrane electrode assembly (MEA) with low Pt loading. However, these high performing MEAs do not meet durability requirements, especially at peak power, because of complex degradation mechanisms that are sensitive to the materials, MEA design, and fuel cell operating strategy. Specifically, power degradation of the cathode occurs via Pt and Co dissolution as well as deterioration of O 2 transport properties. Additionally, thin membranes are subject to failure due to manufacturing defects in the adjacent gas diffusion media and electrodes and the formation of membrane-attacking radical species caused by high gas crossover. In this project led by General Motors LLC (GM), the objective was to enhance the durability of SOA MEA through optimization of operating conditions, instead of new materials development. Along with our project partners, we have mapped the impact of operating conditions on the durability of SOA MEA. Output of the project include a low Pt loading SOA MEA that exceeds Department of Energy (DOE) 2020 target of >1 W/cm 2 at rated power and pathway to achieve >5000 h of durability. Durability studies in the project provide a detailed understanding of failure modes and operating condition sensitivity on cathode and membrane failure, critical for defining operating conditions and hybridization strategies that can guide system controls to maximize low-Pt MEA life. The project also generated and validated degradation models that will provide future research direction, critical for guiding future cycles of automotive MEA development.

08 HYDROGEN↗
DOE OSTI2022

Predicted Impacts of Pt and Ionomer Distributions on Low-Pt-Loaded PEMFC Performance

Low-cost, high performance proton exchange membrane fuel cells (PEMFCs) have been difficult to develop due to limited understanding of coupled processes in the cathode catalyst layer (CCL). Low-Pt-loaded PEMFCs suffer losses beyond those predicted solely due to reduced catalyst area. Although consensus links these losses to thin ionomer films in the CCL, a precise mechanistic explanation remains elusive. In this publication, we present a physically based PEMFC model with novel structure-property relationships for thin-film Nafion, validated against PEMFC data with low Pt loading. Results suggest that flooding exacerbates kinetic limitations in low-loaded PEMFCs, shifting the Faradaic current distribution. As current density increases, protons travel further into the CCL, resulting in higher Ohmic overpotentials. We also present a parametric study of CCL design parameters. We find that graded Pt and ionomer loadings reduce Ohmic losses and flooding, but individually do not provide significant improvements. However, a dual-graded CCL (i.e., graded Pt and ionomer) is predicted to significantly improve the maximum power density and limiting current compared to uniformly loaded CCLs. This work highlights the importance of accurate transport parameters for thin-film Nafion and provides a pathway to low-cost PEMFCs via precise control of CCL microstructures.

08 HYDROGEN↗