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DOE OSTI2025

Multilayer Electrodes with Metalized Polymer Current Collector for High-Energy Lithium-Ion Batteries with Extreme-Fast-Charging Capability

The pursuit of batteries capable of extreme fast charging (XFC), that also satisfy high energy and safety criteria, poses a significant challenge to current lithium-ion battery technologies. Additionally, the increasing demand for aluminum (Al) and copper (Cu) in electrification, and vehicle light weighting is driving these metals towards near-critical status in the medium term. This study introduced metalized polymer films by depositing an Al or Cu thin layer onto two sides of a polyethylene terephthalate (PET) film – named mPET/Al and mPET/Cu, as lightweight, cost-effective alternatives to traditional metal current collectors in LIBs. We have utilized current collectors that significantly reduce weight (by 73%), thickness (by 33%), and cost (by 85%) compared to traditional metal foil counterparts. We conducted an extensive evaluation of their mechanical and electrical properties, including in-plane and through-plane resistivities, affirming their suitability for the roll-to-roll battery manufacturing process. Additionally, a novel XFC testing protocol was employed to thoroughly assess the cells' (both half and full-cell) performance across various C-rates and under long-term tests. These advancements have the potential to enhance energy density to 280 Wh/kg at the electrode level under 10-minute charging at 6C. Through testing, including a novel XFC protocol across various C-rates and long-term cycling (up to 1000 cycles) in different cell configurations, we have demonstrated the superior performance of these metalized polymer films. Notably, mPET/Cu and mPET/Al foils exhibited comparable capacities to conventional cells under XFC, with the mPET cells showing a 27% improvement in energy density at 6C and maintaining significant energy density after 1000 cycles. This study underscored the potential of mPET foils to revolutionize the roll-to-roll battery manufacturing process and significantly advance the performance metrics of LIBs in EV applications. Moreover, our results suggest that there is potential to enhance the performance of mPET foils, especially mPET/Al, by optimizing the manufacturing process to achieve higher conductivity.

99 GENERAL AND MISCELLANEOUS↗

DOE OSTI2019

Performance, Fuel Economy, and Economic Assessment of a Combustion Concept Employing In-Cylinder Gasoline/Natural Gas Blending for Light-Duty Vehicle Applications

In current production natural gas/gasoline bi-fuel vehicles, fuels are supplied via port fuel injection (PFI). Injecting a gaseous fuel in the intake port significantly reduces the volumetric efficiency and consequently torque as compared to gasoline. In addition to eliminating the volumetric efficiency challenge, direct injection (DI) of natural gas (NG) can enhance the in-cylinder flow, mixing, and combustion process resulting in improved efficiency and performance. A computational fluid dynamics (CFD) approach to model high-pressure gaseous injection was developed and validated against X-ray data from Argonne’s Advanced Photon Source. NG side and central DI of various designs and injection strategies were assessed experimentally along with CFD correlation. Significant effects on combustion metrics were quantified and explained via improved understanding of the in-cylinder flow effects due to NG injection. On-demand in-cylinder blending using E10 PFI and NG DI provides an additional lever to adjust in-cylinder turbulence as well as knock resistance across the engine speed and load range. NG DI improves part-load dilution tolerance due to higher in-cylinder turbulence and the high knock resistance of NG compared to E10 improves wide open throttle (WOT) performance while enabling increased compression ratios (CR). Vehicle level simulations suggest that implementing this strategy on a ½ ton pick-up truck with a naturally aspirated engine at 12.5:1 CR improves energy consumption on the aggressive US06 drive cycle by 15.5% compared to E10 operation, and gives a petroleum reduction of 78% over the blended range. There are challenges regarding market acceptance and widespread adoption of dual-fuel NG-gasoline vehicle applications beyond the performance degradation when the vehicle runs out of natural gas. Furthermore, those challenges include practical concerns such as loss of cargo volume and payload due to the NG storage tank, extended NG refueling times, fueling convenience due to gasoline and NG fuel tanks, and limited NG fueling infrastructure.

33 ADVANCED PROPULSION SYSTEMS↗

DOE OSTI2019

AUXILIARY FEEDWATER REHEATING TO MITIGATE PRIMARY AND SECONDARY SIDE THERMAL STRESSORS

A consequence of operating steam cycles under time varying loads, is the variability of the feedwater temperature entering the bottom of the steam generators. This variability is a direct result of changes in turbine impulse pressure and subsequently turbine tap pressures in response to the load changes, with a reduction in feed temperature during periods of low turbine demand. These fluctuations over time will increase thermal cycling and threaten the integrity of the tube bundle as well as other components in the feed system. Sensible heat, TES systems have been shown to be an effective load management strategy allowing nuclear reactor systems to operate at effectively 100% full power while storing excess thermal energy for recovery later. A byproduct of the TES system is the availability of large amounts of low grade waste heat that can be used for ancillary applications, including auxiliary feed heating during periods of low turbine demand. The addition of an auxiliary feed heater at the end of the traditional feed train can minimize feed temperature variations during periods of low turbine demand, reducing the effects of thermal cycling and increasing overall thermodynamic efficiency. This paper discusses the design, operation and control strategies for an auxiliary feed water system as an integral component of a coupled Thermal Energy Storage system and Integral Pressurized Water Reactor. The impact on system performance, particularly as it affects reactor dynamic response and reductions in thermal cycling will be addressed. In addition to the improved thermal efficiency, a benefit of this approach is the relocation of thermal stressors from the reactor coolant system to more easily managed Balance of Plant systems

22 GENERAL STUDIES OF NUCLEAR REACTORS↗

DOE OSTI2015

Energy efficiency, human behavior, and economic growth: Challenges to cutting energy demand to sustainable levels

Increasing energy efficiency in households, transportation, industries, and services is an important strategy to reduce energy service demand to levels that allow the steep reduction of greenhouse gases, and a full fledged switch of energy systems to a renewable basis. Yet, technological efficiency improvements may generate so-called rebound effects, which may ‘eat up’ parts of the technical savings potential. This article provides a comprehensive review of existing research on these effects, raises critiques, and points out open questions. It introduces micro-economic rebound effect and suggests extending consumer-side analysis to incorporate potential ‘psychological rebound effects.’ It then discusses meso-economic rebound effects, i.e. producer-side and market-level rebounds, which so far have achieved little attention in the literature. Finally, the article critically reviews evidence for macro-economic rebound effects as energy efficiency-induced economic growth impacts. For all three categories, the article summarizes assessments of their potential quantitative scope, while pointing out remaining methodological weaknesses and open questions. As a rough “rule of thumb”, in the long term and on gross average, only half the technical savings potential of across-the-board efficiency improvements may actually be achieved in the real world. Policies that aim at cutting energy service demand to sustainable levels are well advised to take due note of detrimental behavioral and economic growth impacts, and should foster policies and measures that can contain them.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

DOE OSTI2016

Composition and Realization of Source-to-Sink High-Performance Flows: File Systems, Storage, Hosts, LAN and WAN

A number of Department of Energy (DOE) science applications, involving exascale computing systems and large experimental facilities, are expected to generate large volumes of data, in the range of petabytes to exabytes, which will be transported over wide-area networks for the purpose of storage, visualization, and analysis. To support such capabilities, significant progress has been made in various components including the deployment of 100 Gbps networks with future 1 Tbps bandwidth, increases in end-host capabilities with multiple cores and buses, capacity improvements in large disk arrays, and deployment of parallel file systems such as Lustre and GPFS. High-performance source-to-sink data flows must be composed of these component systems, which requires significant optimizations of the storage-to-host data and execution paths to match the edge and long-haul network connections. In particular, end systems are currently supported by 10-40 Gbps Network Interface Cards (NIC) and 8-32 Gbps storage Host Channel Adapters (HCAs), which carry the individual flows that collectively must reach network speeds of 100 Gbps and higher. Indeed, such data flows must be synthesized using multicore, multibus hosts connected to high-performance storage systems on one side and to the network on the other side. Current experimental results show that the constituent flows must be optimally composed and preserved from storage systems, across the hosts and the networks with minimal interference. Furthermore, such a capability must be made available transparently to the science users without placing undue demands on them to account for the details of underlying systems and networks. And, this task is expected to become even more complex in the future due to the increasing sophistication of hosts, storage systems, and networks that constitute the high-performance flows. The objectives of this proposal are to (1) develop and test the component technologies and their synthesis methods to achieve source-to-sink high-performance flows, and (2) develop tools that provide these capabilities through simple interfaces to users and applications. In terms of the former, we propose to develop (1) optimization methods that align and transition multiple storage flows to multiple network flows on multicore, multibus hosts; and (2) edge and long-haul network path realization and maintenance using advanced provisioning methods including OSCARS and OpenFlow. We also propose synthesis methods that combine these individual technologies to compose high-performance flows using a collection of constituent storage-network flows, and realize them across the storage and local network connections as well as long-haul connections. We propose to develop automated user tools that profile the hosts, storage systems, and network connections; compose the source-to-sink complex flows; and set up and maintain the needed network connections. These solutions will be tested using (1) 100 Gbps connection(s) between Oak Ridge National Laboratory (ORNL) and Argonne National Laboratory (ANL) with storage systems supported by Lustre and GPFS file systems with an asymmetric connection to University of Memphis (UM); (2) ORNL testbed with multicore and multibus hosts, switches with OpenFlow capabilities, and network emulators; and (3) 100 Gbps connections from ESnet and their Openflow testbed, and other experimental connections. This proposal brings together the expertise and facilities of the two national laboratories, ORNL and ANL, and UM. It also represents a collaboration between DOE and the Department of Defense (DOD) projects at ORNL by sharing technical expertise and personnel costs, and leveraging the existing DOD Extreme Scale Systems Center (ESSC) facilities at ORNL.

97 MATHEMATICS AND COMPUTING↗

DOE OSTI2018

Transatlantic wood pellet trade demonstrates telecoupled benefits

European demand for renewable energy resources has led to rapidly increasing transatlantic exports of wood pellets from the southeastern United States (SE US) since 2009. Disagreements have arisen over the global greenhouse gas reductions associated with replacing coal with wood, and groups on both sides of the Atlantic Ocean have raised concerns that increasing biomass exports might negatively affect SE US forests and the ecosystem services they provide. We use the telecoupling framework to test assertions that the intended benefits of the wood pellet trade for Europe might be offset by negative consequences in the SE US. Through a review of current literature and available data sets, we characterize the observed and potential changes in the environmental, social, and economic components of the sending and receiving regions to assess the overall sustainability of this renewable energy system. We conclude that the observed transatlantic wood pellet trade is an example of a mutually beneficial telecoupled system with the potential to provide environmental and socioeconomic benefits in both the SE US and Europe despite some negative effects on the coal industry. We recommend continued monitoring of this telecoupled system to quantify the environmental, social, and economic interactions and effects in the sending, receiving, and spillover systems over time so that evidence-based policy decisions can be made with regard to the sustainability of this renewable energy pathway.

32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATI↗

DOE OSTI2012

Optimization Of Chromaticity Compensation And Dynamic Aperture In MEIC Collider Rings

The conceptual design of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab relies on an ultra-small beta-star to achieve high luminosities of up to 10{sup 34} cm{sup -2} s{sup -1}. A low-beta insertion for interaction regions unavoidably induces large chromatic effects that demand a proper compensation. The present approach of chromatic compensation in the MEIC collider rings is based on a local correction scheme using two symmetric chromatic compensation blocks that includes families of sextupoles, and are placed in a beam extension area on both sides of a collision point. It can simultaneously compensate the first order chromaticity and chromatic beam smear at the IP without inducing significant second order aberrations. In this paper, we investigate both the momentum acceptance and dynamic aperture in the MEIC ion collider ring by considering the aberration effects up to the third order, such as amplitude dependent tune shift. We also explore the compensation of the third order effects by introducing families of octupoles in the extended beam area.

43 PARTICLE ACCELERATORS↗

NASA NTRS1992

Strongly transitive fuzzy relations: A more adequate way to describe similarity

The notion of a transitive closure of a fuzzy relation is very useful for clustering in pattern recognition, for fuzzy databases, etc. It is based on translating the standard definition of transitivity and transitive closure into fuzzy terms. This definition works fine, but to some extent it does not fully capture our understanding of transitivity. The reason is that this definition is based on fuzzifying only the positive side of transitivity: if R(a,b) and R(b,c), then R(a,c); but transitivity also includes a negative side: if R(a,b) and not R(a,c), then not R(b,c). In classical logic, this negative statement follows from the standard 'positive' definition of transitivity. In fuzzy logic, this negative part of the transitivity has to be formulated as an additional demand. A strongly transitive fuzzy relation as the one that satisfies both the positive and the negative transitivity demands is defined, the existence of strongly transitive closure is proven, and the relationship between strongly transitive similarity and clustering are found.

Kreinovich, Vladik YA.↗

DOE OSTI2017

Has pellet production affected SE US forests?

Wood pellet export volumes from the Southeastern United States (SE US) to Europe have been growing since 2009, leading to concerns about potential environmental effects. Biomass pellets are intended to reduce carbon emissions and slow global warming by replacing coal in European power plants. Yet, stakeholders on both sides of the Atlantic Ocean worry that increased pellet production might lead to changes in SE US forests that harm water and soil quality, or endanger sensitive species—such as birds, tortoises, and snakes—and their habitats. Stakeholders have also expressed concern that increasing pellet demand might accelerate a fifty-year trend in which naturally regenerating mixed hardwood and pine forests native to the SE US are being replaced by plantation pine forests.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

Technetium oxidation in slag-based sodium salt waste forms exposed to water and moist Hanford soil - 15514

Several U.S. DOE sites use or plan to use waste forms and/or concrete containment structures for radioactive waste disposal that are designed to have a chemically reducing environment to immobilize selected contaminants such as Tc(VII)O{sub 4}{sup -} and Cr(VI)O{sub 4}{sup 2-}. These waste forms and containment structures are typically deployed in near surface unsaturated oxidizing environments. Consequently, the effect of exposure to air (oxygen) and water containing dissolved oxygen during production, during the period of institutional control, and over the long term period of performance is important for predicting the speciation and mobility of the redox sensitive radioactive and stable contaminants. Both the SRS and Hanford waste streams contain soluble technetium which may require stabilization to meet disposal requirements. Technetium stabilization is a difficult problem because: 1) Tc is soluble and very mobile in the oxidized form typical of near surface environments, and 2) Tc-99 is a long-lived isotope with a half-life of 2.1 E+05 years which places demanding requirements on the engineered barriers and environment to meet current regulatory disposal requirements. A depth-discrete sampling and leaching method approach for measuring contaminant oxidation rate (effective contaminant specific oxidation rate) was used in this study. The method was modified by coating all sides of a cylindrical sample with an impermeable epoxy and cutting a fresh surface 2 to 2.5 cm from the original top surface eliminates sample inhomogeneity as the result of settling as a reason from observed results and provides 1-D soluble ion transport and gas transport information. Soluble Tc was leached from all of the depth-discrete sub-samples from both Tc2-9 and Tc2-10 which strongly suggests that oxygen was present in the entire length of both samples. About 24 mass percent of the Tc in the original sample, was leached (soluble) from sub-samples between 0.8 and 46 mm below the exposed surface of Tc2-9 (exposed to Hanford sediment). The same percent (24%) was leached from the sub-samples between 0.8 and 11 mm below the exposed surface of Tc2-10 (exposed to DI water). This suggests that the rate of oxygen migration into the sample exposed to soil was faster than the rate of migration into the sample exposed to water which is consistent with the more rapid transport of ions through a gas phase as compared to a liquid phase. It is assumed that moisture in the Hanford sediment was not sufficient to completely block the surface pores with respect to gas transport across the soil-waste form boundary. Based on nitrate leaching results for the depth- discrete sub-samples, regions depleted in nitrates were identified from the top surfaces to 9.5 and 3 mm into samples Tc2-9 (exposed to moist Hanford sediment) and Tc2-10 (DI water). Low mass fractions of nitrate were leached from these depth-discrete samples compared to samples further from the exposed surface presumably because a significant portion of the nitrate had already migrated into the soil or water, respectively. Depth-discrete sub-sample leaching results for Na can be interpreted in the same way over the same regions in the two samples tested. In conclusion, leaching monolithic porous cementitious waste forms in water appears to be conservative for non-redox sensitive contaminants. However, leaching data obtained under saturated exposure conditions do not appear to be conservative for redox sensitive contaminants which are easily oxidized. Leaching crushed samples in water still seems to be a conservative approach to estimating the concentrations of soluble contaminants in a waste form. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS1994

Bipolar Ag-Zn battery

The silver-zinc (AgZn) battery system has been unique in its ability to safely satisfy high power demand applications with low mass and volume. However, a new generation of defense, aerospace, and commercial applications will impose even higher power demands. These new power demands can be satisfied by the development of a bipolar battery design. In this configuration the power consuming, interelectrode current conductors are eliminated while the current is then conducted via the large cross-section electrode substrate. Negative and positive active materials are applied to opposite sides of a solid silver foil substrate. In addition to reducing the weight and volume required for a specified power level, the output voltage performance is also improved as follows. Reduced weight through: elimination of the plastic cell container; elimination of plate leads and intercell connector; and elimination of internal plate current collector. Increased voltage through: elimination of resistance of current collector; elimination of resistance of plate lead; and elimination of resistance of intercell connector. EPI worked previously on development of a secondary bipolar silver zinc battery. This development demonstrated the electrical capability of the system and manufacturing techniques. One difficulty with this development was mechanical problems with the seals. However, recent improvements in plastics and adhesives should eliminate the major problem of maintaining a seal around the periphery of the bipolar module. The seal problem is not as significant for a primary battery application or for a requirement for only a few discharge cycles. A second difficulty encountered was with activation (introducing electrolyte into the cell) and with venting gas from the cell without loss of electrolyte. During previous work, the following projections for energy density were made from test data for a high power system which demonstrated in excess of 50 discharge/charge cycles. Projected system power = 100 kilowatts; discharge time = 30 seconds; discharge current density = 1.75 amps/sq in.; system weight = 86 lbs (9.7 WH/lb); and system volume = 1071 cu. in. (.78 WH/cu. in.). EPI is currently working on a development program to produce a bipolar silver-zinc battery design for NASA. The potential application would be to power electromechanical actuators for space launch vehicles.

Giltner, L. John↗

NASA NTRS2019

Early Prototype Development of the Passive Orbital Nutrient Delivery System (PONDS)

Long-duration space missions will eventually require a fresh food supply to supplement crew diets, which means growing crops in space. The Passive Orbital Nutrient Delivery System (PONDS) is a new plant growth approach that contains both an area for a contained substrate and a reservoir for water and/or plant nutrient solutions. Ground studies have shown that the system facilitates both reliable water delivery to seeds for germination (e.g., while avoiding overwatering), and transport of water from the reservoir for improved plant growth while providing nutrients and oxygen to the root zone. In ground prototypes a capillary mat wicking material passively links the water/nutrient solution reservoir to a removable rooting module containing a substrate adapted to support plant growth. Oxygen permeable membranes are incorporated into both the reservoir walls and the rooting modules, bringing in oxygen from outside of the system into the reservoir and then into the rooting modules where the plant roots proliferate. Water is delivered from the reservoir to the substrate contained within the rooting module through the use of wicking material inserted into the plant growth substrate both from the bottom and from the sides of the rooting module. The capillary mat material is intrinsically hydrophilic and continuously wicks water to the substrate throughout the plant growth interval. The system is therefore self-watering in terms of supplying water to the root zone encompassed within the rooting module on demand. At the top, a hydrophilic phenolic foam plug surrounds the wick in the seed insertion zone, and both contains the substrate within the rooting module, and facilitates removal of excess moisture from the capillary mat wick before it can encompass seeds prior to germination. This work is supported by NASA’s Space Life and Physical Sciences and Research Applications Division (SLPSRAD).

Levine, Howard G.↗

DOE OSTI2021

BETO 2021 Peer Review - WBS 4.1.2.32: Bioeconomy Scenario Analysis

The Bioeconomy Scenario Analysis project uses systems thinking and analysis to assess current and/or prospective techno-economics, research and development, deployment strategies, policy, and market conditions and their impact on the potential development trajectories of the bioenergy industry over time. Results from this project include identification of opportunities and constraints to industrial development, quantification of multiple metrics (energy, economic, environmental) and informing researchers, decision makers, and industry of the steps needed for a sustainable, nationwide biofuels industry. Analyses from this project enable the creation of a bioenergy industry by (1) inciting policy-makers to explore scenarios for nationwide biofuels production, identifying policy actions consistent with pathways for growth; (2) improving industry’s understanding of industry growth potential under different technology and investment conditions, better targeting their development efforts; and (3) providing universities and other interested stakeholders with tools and analyses that can be adapted to meet research and teaching objectives, connecting students with careers that build the industry. One of the many modeling tools used in this project, the Biomass Scenario Model (BSM) is a publicly-available, unique, validated, state-of-the-art, award-winning, fourth-generation model of the domestic biofuels supply chain which explicitly focuses on how and under what conditions biofuel technologies might be deployed to contribute to the U.S. transportation energy sector. We use models like the BSM to examine the implications of policies and incentives as well as their potential side-effects. The BSM uses a system-dynamics simulation to model dynamic interactions and transitions across the supply chain; it tracks the deployment of biofuels given industrial learning and the reaction of the investment community in the context of land availability, projected oil markets, consumer demand for biofuels, and government policies over time. Under expected market conditions, analyses using the BSM suggest that the biofuels industry may require significant external actions in the early years to thrive. Interventions that accelerate the industrial learning process (e.g. operation of pre-commercial and commercial facilities) have been identified as having strong influence in starting the growth of a commercial biofuel industry. Policies which are coordinated across the whole supply chain in BSM foster the growth of the biofuels industry and production of tens of billions of gallons of biofuels may occur under sufficiently favorable conditions.

29 ENERGY PLANNING, POLICY, AND ECONOMY↗

NASA NTRS1992

Robot Serviced Space Facility

A robot serviced space facility includes multiple modules which are identical in physical structure, but selectively differing in function. and purpose. Each module includes multiple like attachment points which are identically placed on each module so as to permit interconnection with immediately adjacent modules. Connection is made through like outwardly extending flange assemblies having identical male and female configurations for interconnecting to and locking to a complementary side of another flange. Multiple rows of interconnected modules permit force, fluid, data and power transfer to be accomplished by redundant circuit paths. Redundant modules of critical subsystems are included. Redundancy of modules and of interconnections results in a space complex with any module being removable upon demand, either for module replacement or facility reconfiguration. without eliminating any vital functions of the complex. Module replacement and facility assembly or reconfiguration are accomplished by a computer controlled articulated walker type robotic manipulator arm assembly having two identical end-effectors in the form of male configurations which are identical to those on module flanges and which interconnect to female configurations on other flanges. The robotic arm assembly moves along a connected set or modules by successively disconnecting, moving and reconnecting alternate ends of itself to a succession of flanges in a walking type maneuver. To transport a module, the robot keeps the transported module attached to one of its end-effectors and uses another flange male configuration of the attached module as a substitute end-effector during walking.

Purves, Lloyd R.↗

NASA NTRS1980

Silicon ribbon growth using scanned lasers

The recent demand for low-cost photovoltaic arrays has renewed the interest in growing silicon in ribbon form. The approach used in the present paper for the growth of low-cost silicon ribbon is shown schematically. A pair of scanned, focused CO2 laser beams is directed onto both sides of a preformed silicon ribbon. A narrow (about 1 mm high) molten zone is formed across the full width of the ribbon. As the silicon ribbon is passed through the laser-heated zone, large grains are produced in the recrystallized ribbon. The laser beam path is outlined schematically. As a general rule, the lenses are not positioned so as to bring the laser beams to a fine focus, since highly focused beams would vaporize the silicon surface rather than serve to melt the bulk. Silicon ribbon has been grown at rates up to 13.3 cm/min by this approach. The best solar cell fabricated so far on this material has a conversion efficiency of 12.7%.

Baghdadi, A.↗

DOE OSTI2025

Metalized Polymer Current Collector for High-Energy Lithium-Ion Batteries with Extreme Fast-Charging Capability

Electric vehicles are pivotal in the global shift toward decarbonizing road transport, with lithium-ion batteries at the heart of this technological evolution. However, the pursuit of batteries capable of extremely fast charging that also satisfy high energy and safety criteria, poses a significant challenge to current lithium-ion batteries technologies. Additionally, the increasing demand for aluminum (Al) and copper (Cu) in electrification, solar energy technologies, and vehicle light-eighting is driving these metals toward near-critical status in the medium term. This study introduces metalized polythylene terephthalate (mPET) polymer films by depositing an Al or Cu thin layer onto two sides of a polyethylene terephthalate film—named mPET/Al and mPET/Cu, as lightweight, cost-effective alternatives to traditional metal current collectors in lithium-ion batteries. We have fabricated current collectors that significantly reduce weight (by 73%), thickness (by 33%), and cost (by 85%) compared with traditional metal foil counterparts. These advancements have the potential to enhance energy density to 280 Wh kg -1 at the electrode level under 10-min charging at 6 C. Through testing, including a novel extremely fast charging protocol across various C-rates and long-term cycling (up to 1000 cycles) in different cell configurations, the superior performance of these metalized polymer films has been demonstrated. Notably, mPET/Cu and mPET/Al films exhibited comparable capacities to conventional cells under extremely fast charging, with the mPET cells showing a 27% improvement in energy density at 6 C and maintaining significant energy density after 1000 cycles. This study underscores the potential of mPET films to revolutionize the roll-to-roll battery manufacturing process and significantly advance the performance metrics of lithium-ion batteries in electric vehicles applications.

25 ENERGY STORAGE↗

NASA NTRS1987

Duct flow nonuniformities for Space Shuttle Main Engine (SSME)

A three-duct Space Shuttle Main Engine (SSME) Hot Gas Manifold geometry code was developed for use. The methodology of the program is described, recommendations on its implementation made, and an input guide, input deck listing, and a source code listing provided. The code listing is strewn with an abundance of comments to assist the user in following its development and logic. A working source deck will be provided. A thorough analysis was made of the proper boundary conditions and chemistry kinetics necessary for an accurate computational analysis of the flow environment in the SSME fuel side preburner chamber during the initial startup transient. Pertinent results were presented to facilitate incorporation of these findings into an appropriate CFD code. The computation must be a turbulent computation, since the flow field turbulent mixing will have a profound effect on the chemistry. Because of the additional equations demanded by the chemistry model it is recommended that for expediency a simple algebraic mixing length model be adopted. Performing this computation for all or selected time intervals of the startup time will require an abundance of computer CPU time regardless of the specific CFD code selected.

Source record↗

NASA NTRS2006

FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers

A family of experimental highly miniaturized field-effect transistors (FETs) is based on exploitation of the electrical properties of nanofibers of polyaniline/ polyethylene oxide (PANi/PEO) doped with camphorsulfonic acid. These polymer-based FETs have the potential for becoming building blocks of relatively inexpensive, low-voltage, highspeed logic circuits that could supplant complementary metal oxide/semiconductor (CMOS) logic circuits. The development of these polymerbased FETs offers advantages over the competing development of FETs based on carbon nanotubes. Whereas it is difficult to control the molecular structures and, hence, the electrical properties of carbon nanotubes, it is easy to tailor the electrical properties of these polymerbased FETs, throughout the range from insulating through semiconducting to metallic, through choices of doping levels and chemical manipulation of polymer side chains. A further advantage of doped PANi/PEO nanofibers is that they can be made to draw very small currents and operate at low voltage levels, and thus are promising for applications in which there are requirements to use many FETs to obtain large computational capabilities while minimizing power demands. Fabrication of an experimental FET in this family begins with the preparation of a substrate as follows: A layer of silicon dioxide between 50 and 200 nm thick is deposited on a highly doped (resistivity 0.01 W.cm) silicon substrate, then gold electrodes/contact stripes are deposited on the oxide. Next, one or more fibers of camphorsulphonic acid-doped PANi/PEO having diameters of the order of 100 nm are electrospun onto the substrate so as to span the gap between the gold electrodes (see Figure 1). Figure 2 depicts measured current-versus-voltage characteristics of the device of Figure 1, showing that saturation channel currents occur at source-todrain potentials that are surprisingly low, relative to those of CMOS FETs. The hole mobility in the depletion regime in this transistor was found to be 1.4 10(exp -4) sq cm/(V.s), while the one-dimensional charge density at zero gate bias was estimated to be approximately one hole per 50 two-ring repeat units of polyaniline, consistent with the rather high channel conductivity (approx. 10(exp -3) S/cm). Reducing or eliminating the PEO content of the fibers is expected to enhance the properties of future versions of this transistor.

Theofylaktos, Noulie↗