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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Nickel Hydroxide Nanofluid Cathodes with High Solid Loadings and Low Viscosity for Energy Storage Applications

Nanofluid electrodes with high loading of active solid materials have significant potential as high energy density flow battery electrolytes; however, two key criteria need to be met: they must have a manageable viscosity for pumping and simultaneously exhibit good electrochemical activity. A typical dispersion of nickel hydroxide nanoparticles (~100 nm) is limited to 5–10 wt.% of solids, above which it has a paste-like consistency, incompatible with flow applications. We report on the successful formulation of stable dispersions of a nano-scale nickel hydroxide cathode (β-Ni(OH) 2 ) with up to 60 wt.% of solids and low viscosity (32 cP at 25 °C), utilizing a surface graft of small organic molecules. The fraction of grafting moiety is less than 3 wt.% of the nanoparticle weight, and its presence is crucial for the colloidal stability and low viscosity of suspensions. Electrochemical testing of the pristine and modified β-Ni(OH) 2 nanoparticles in the form of solid casted electrodes were found to be comparable with the latter exhibiting a maximum discharge capacity of ~237 mAh/g over 50 consecutive charge–discharge cycles, close to the theoretical capacity of 289 mAh/g.

25 ENERGY STORAGE↗
DOE OSTI2023

Accelerating the development of a sustainable bioenergy portfolio through stable isotopes

Bioenergy could help limit global warming to 2°C above pre-industrial levels while supplying almost a fourth of the world's renewable energy needs by 2050. However, the deployment of bioenergy raises concerns that adoption at meaningful scales may lead to unintended negative environmental consequences. Meanwhile, the full consolidation of a bioenergy industry is currently challenged by a sufficient, resilient, and resource-efficient biomass supply and an effective conversion process. Here, we provide a comprehensive analysis of how stable isotope approaches have accelerated the development of a robust bioeconomy by advancing knowledge about environmental sustainability, feedstock development, and biological conversion. We show that advances in stable isotope research have generated crucial information to (1) gain mechanistic insight into the potential of bioenergy crops to mitigate climate change as well as their impact on water and nutrient cycling; (2) develop high-yielding, resilient feedstocks that produce high-value bioproducts in planta; and (3) engineer microbes to enhance feedstock conversion to bioenergy products. Further, we highlight knowledge gaps that could benefit from future research facilitated by stable isotope approaches. We conclude that advances in mechanistic knowledge and innovations within the field of stable isotopes in cross-disciplinary research actions will greatly contribute to breaking down the barriers to establishing a robust bioeconomy.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2022

Hydroxyl Conducting Hydrogels Enable Low-Maintenance Commercially Sized Rechargeable Zn–MnO2 Batteries for Use in Solar Microgrids

Zinc (Zn)–manganese dioxide (MnO2) rechargeable batteries have attracted research interest because of high specific theoretical capacity as well as being environmentally friendly, intrinsically safe and low-cost. Liquid electrolytes, such as potassium hydroxide, are historically used in these batteries; however, many failure mechanisms of the Zn–MnO2 battery chemistry result from the use of liquid electrolytes, including the formation of electrochemically inert phases such as hetaerolite (ZnMn2O4) and the promotion of shape change of the Zn electrode. This manuscript reports on the fundamental and commercial results of gel electrolytes for use in rechargeable Zn–MnO2 batteries as an alternative to liquid electrolytes. The manuscript also reports on novel properties of the gelled electrolyte such as limiting the overdischarge of Zn anodes, which is a problem in liquid electrolyte, and finally its use in solar microgrid applications, which is a first in academic literature. Potentiostatic and galvanostatic tests with the optimized gel electrolyte showed higher capacity retention compared to the tests with the liquid electrolyte, suggesting that gel electrolyte helps reduce Mn3+ dissolution and zincate ion migration from the Zn anode, improving reversibility. Cycling tests for commercially sized prismatic cells showed the gel electrolyte had exceptional cycle life, showing 100% capacity retention for >700 cycles at 9.5 Ah and for >300 cycles at 19 Ah, while the 19 Ah prismatic cell with a liquid electrolyte showed discharge capacity degradation at 100th cycle. We also performed overdischarge protection tests, in which a commercialized prismatic cell with the gel electrolyte was discharged to 0 V and achieved stable discharge capacities, while the liquid electrolyte cell showed discharge capacity fade in the first few cycles. Finally, the gel electrolyte batteries were tested under IEC solar off-grid protocol. It was noted that the gelled Zn–MnO2 batteries outperformed the Pb–acid batteries. Additionally, a designed system nameplated at 2 kWh with a 12 V system with 72 prismatic cells was tested with the same protocol, and it has entered its third year of cycling. This suggests that Zn–MnO2 rechargeable batteries with the gel electrolyte will be an ideal candidate for solar microgrid systems and grid storage in general.

25 ENERGY STORAGE↗
DOE OSTI2023

Tuning Discharge Behavior of Hollandite α-MnO 2 in Hydrated Zinc Ion Battery by Transition Metal Substitution

The tunnel-type hollandite α-MnO 2 is a promising cathode material for rechargeable aqueous zinc-ion batteries (ZIBs) due to its low cost in synthesis and high energy density. However, irreversible structural degradation upon continuous cycling prevents the cathode from being utilized commercially. Herein, density functional theory (DFT) was utilized to conduct a systematic study on tuning the behavior of α-MnO 2 by substituting the Mn ions on the tunnel wall with a transition metal (V or Cr) during the H + -/Zn 2+ -intercalation in hydrated ZIB. Our study revealed that both substituents aid cyclability and capacity retention with Cr outperforming V. In term of discharge voltage, only the Cr-substitution displays clear promotion at the early stage of discharge. The superior performance of substituted Cr 4+ comes from its unique atomic and electronic structures. Upon discharge, it can be reduced to Cr 3+ more readily than Mn 4+ and thereby limits the formation of unstable Mn 3+ or Mn 2+ centers; the formed Cr 3+ is more stable than Mn 3+ and Mn 2+ from the reduction of Mn 4+ ; and Cr 3+ can also greatly stabilize the neighboring Mn ions. Here this study highlights the significant tuning effect of transition metal substitution on the electrochemical and physical performance of α-MnO 2 as a cathode in hydrated ZIBs.

25 ENERGY STORAGE↗
DOE OSTI2020

Plasma enhanced atomic layer deposition of thin film Li 1+x Mn 2-x O 4 for realization of all solid-state 3D lithium-ion microbatteries

Here, the plasma enhanced atomic layer deposition (PEALD) process for MnO 2 was demonstrated, exhibiting self-limiting growth as well as stable composition and stable growth rate over a temperature window of 205–265 °C. The PEALD process for MnO 2 was combined with the thermal ALD process for LiOH to synthesize Li 1+x Mn 2-x O 4 thin film cathodes, where the stoichiometry was effectively controlled to allow for crystallization in the electrochemically active spinel phase. A 3D nanostructure consisting of an Li 1+x Mn 2-x O 4 cathode layer, ALD Li x Al y Si z O solid electrolyte, and SiGe nanowire anode was fabricated and characterized via TEM. The Li 1+x Mn 2-x O 4 thin films maintained 66% of the areal capacity upon a 100× increase in the rate (4–360 μ A cm -2 ) as well as 97% capacity retention over 100 cycles at ~5C. The ALD Li 1+x Mn 2-x O 4 thin films exhibited a volumetric capacity of 52 μ Ah cm -2 μ m -1 at a C-rate of ~0.5C and, coupled with the high operating voltage (4.0 V), offer some of best areal energy densities for ALD thin film cathodes, making it a viable material for integration with 3D lithium-ion microbatteries.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Lithium Growth on Alloying Substrates and Effect on Volumetric Expansion

The widespread implementation of next-generation Li metal anodes is limited, in part, due to the formation of dendritic and/or mossy electrodeposits during cycling. These morphologies can lead to battery failure due to the formation of short circuits and significant volumetric expansion at the anode. One strategy to control the electrodeposition of Li metal is to use lithiophilic materials at the anode. Here, we evaluate the impact of Ag and Au on the early stages of Li metal electrodeposition and cycling. The alloying substrates decrease the voltage for Li reduction and improve Li wetting/adhesion. We probe volumetric expansion directly through dilatometry measurements and find that the degree of volumetric expansion is less when lithium is cycled on an alloying substrate compared to a non-alloying substrate (Cu). Dilatometry experiments reveal that Au has the least amount of volumetric expansion and coin cell cycling experiments indicate that Ag yields more stable cycling compared to Au or Cu. The evaluation of in situ cross-sectional images of cycled coin cells shows that Ag has the lowest volumetric expansion in a coin cell format.

alloys↗
DOE OSTI2022

High-Temperature RF Transmission Loss Characteristics of Platinum–Inconel 600 and Platinum–304 Steel Interconnects

Radio frequency (RF) transmission losses that occur at electronic interconnects is currently an important limitation of wireless sensors and other electronic device packages that must operate in high-temperature environments. Herein, in-situ RF transmission losses were measured for two types of interconnects: platinum (Pt) wire bonded to an Inconel 600 coaxial cable; and Pt-wire bonded to a block of 304 steel. Heating the Pt wire/Inconel interconnects at 800 °C for up to 200 hours were found to be very stable with no measurable transmission losses. In contrast, Pt wire/304 steel block interconnects examined over similar test periods at 800 °C exhibited gradual increases in transmission losses leveling off at 10, 38 and 85 mdB at 400 MHz, 700 MHz, and 1 GHz, respectively. Increasing the test temperature to 900 °C caused further elevated transmission losses of 30, 70 and 108 mdB at the same reported frequencies. By comparison, temperature cycling of the Pt wire/304 steel interconnects between room temperature and 900 °C was found to cause more significant degradation. In particular, four thermal cycles from room temperature to 900 °C resulted in losses of 75, 271, and 482 mdB at the same reported frequencies. Parabolic oxidation relative to the RF skin depth in the 304 steel block at the tested frequencies are discussed as possible reasons for the transmission losses during the isothermal soaks, whereas interconnect degradation due to differences in thermal expansion between Pt and 304 steel are primarily responsible for transmission losses caused by high temperature cycling.

304 steel↗
DOE OSTI2022

High Current-Density-Charging Lithium Metal Batteries Enabled by Double-Layer Protected Lithium Metal Anode

The practical application of lithium (Li) metal anode (LMA) is still hindered by non-uniformity of solid electrolyte interphase (SEI), formation of "dead" Li, and continuous consumption of electrolyte although LMA has an ultrahigh theoretical specific capacity and a very low electrochemical redox potential. Herein, we report a facile protection strategy for LMA using a double layer (DL) coating that consists of a polyethylene oxide (PEO)-based bottom layer which is highly stable with LMA and promotes uniform ion flux, and a cross-linked polymer-based top layer which prevents solvation of PEO layer in electrolytes. Li deposited on DL-coated Li (DL@Li) exhibits a smoother surface and much larger size than that deposited on bare Li. The LiF/Li 2 O enriched SEI layer generated by the salt decomposition on top of DL@Li further suppresses the side reactions between Li and electrolyte. Driven by the abovementioned advantageous features, the DL@Li||LiNi 0.6 Mn 0.2 Co 0.2 O 2 cells demonstrate capacity retention of 92.4% after 220 cycles at a current density of 2.1 mA cm -2 (C/2 rate) and stability at a high charging current density of 6.9 mA cm -2 (1.5C rate). These results indicate that the DL protection is promising to overcome the rate limitation of LMAs and high energy-density Li metal batteries.

25 ENERGY STORAGE↗
DOE OSTI2024

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

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

25 ENERGY STORAGE↗
DOE OSTI2021

Density functional theory calculations of the thermodynamic and kinetic properties of point defects in β -U

Density functional theory (DFT) calculations of the thermodynamic and kinetic properties of point defects in the β phase of uranium are reported. Defect energies and entropies were calculated using 2 x 2 x 2 supercells and the Generalized Gradient Approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) for the exchange-correlation potential. Due to computational cost, calculations of the vibrational properties governing entropies were performed by only displacing atoms within (roughly) the 3rd or 4th nearest neighbor shell of the defect, which implicitly assumes that atoms beyond this distance are unaffected by the defect. Migration barriers were estimated by nudged elastic band (NEB) calculations. The low symmetry of the β-U phase (the unit cell is tetragonal and contains 30 atoms) results in many point defect configurations and even more migration pathways. A connectivity map, starting from the most stable point defects, was developed in order to identify the rate-limiting step controlling the net diffusion rate in each crystallographic direction. The uranium self-diffusivity tensor was calculated by combining the defect formation energies, entropies, migration barriers and attempt frequencies. The fastest diffusion rate was determined to be a vacancy mechanism in the z crystallographic direction. The predicted uranium self-diffusivity for this mechanism agrees well with available experimental data. Finally, the diffusion mechanisms and rates identified in this study will inform fuel performance models of swelling and gas evolution.

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS↗
DOE OSTI2023

Anion-tethered Single Lithium-ion Conducting Polyelectrolytes through UV-induced Free Radical Polymerization for Improved Morphological Stability of Lithium Metal Anodes

Single Li + ion conducting polyelectrolytes (SICs), which feature covalently tethered counter-anions along their backbone, have the potential to mitigate dendrite formation by reducing concentration polarization and preventing salt depletion. However, due to their low ionic conductivity and complicated synthetic procedure, the successful validation of these claimed advantages in lithium metal (Li 0 ) anode batteries remains limited. In this study, we fabricated a SIC electrolyte using a single-step UV polymerization approach. The resulting electrolyte exhibited a high Li + transference number (t + ) of 0.85 and demonstrated good Li + conductivity (6.3×10 -5 S/cm at room temperature), which is comparable to that of a benchmark dual ion conductor (DIC, 9.1×10 -5 S/cm). Benefitting from the high transference number of SIC, it displayed a three-fold higher critical current density (2.4 mA/cm 2 ) compared to DIC (0.8 mA/cm 2 ) by successfully suppressing concentration polarization-induced short-circuiting. Additionally, the t + significantly influenced the deposition behavior of Li0, with SIC yielding a uniform, compact, and mosaic-like morphology, while the low t + DIC resulted in a porous morphology with Li 0 whiskers. Using the SIC electrolyte, Li 0 ||LiFePO 4 cells exhibited stable operation for 4500 cycles with 70.5 % capacity retention at 22 °C.

25 ENERGY STORAGE↗
DOE OSTI2021

Origin of water masses in Floridan Aquifer System revealed by 81 Kr

Groundwater in coastal aquifers serves as an essential resource in densely populated areas throughout the world. However, hydrological connection to the ocean leaves it at risk of salinization via changes in climate and hydrological cycles. Therefore, an accurate hydrological characterization of coastal aquifers is of the utmost importance. Although localized salinization of shallow aquifers has commonly been studied, geochemical constraints on the time scale of regional freshwater and seawater in coastal aquifers are limited especially in carbonate aquifers. Such information is not only crucial for water resource management, but also for understanding solute flux over the land-ocean boundary and for interpreting the geochemical signatures that each water mass carries. Toward this goal, we report tracer-based, subsurface residence times of groundwater in the Floridan Aquifer System in southern Florida, which is one of the most productive aquifers on Earth. The first application of Kr 81-an emerging tracer of old groundwater-to this aquifer has identified freshwater recharge during the last glacial period as anticipated from previous studies using other geochemical tools including radiocarbon, stable isotopes and noble gas concentrations. Moreover, freshwater of Holocene age was also detected at 100 km-distance from the recharge area, suggesting the possibility of an active flow system in the upgradient region. A contribution of fossil seawater that predates the last glacial maximum was locally identified, suggesting slow seawater circulation and limited but significant solute flux from the ocean into the aquifer for dolomitization. This also implies that the deep saline coastal groundwater can potentially serve as a paleo-seawater archive.

58 GEOSCIENCES↗
DOE OSTI2024

In Situ Alloying Enabled by Active Liquid Metal Filler for Self‐Healing Composite Polymer Electrolytes

Abstract Solid inorganics, known for kinetically inhibiting polymer crystallization and enhancing ionic conductivity, have attracted significant attention in solid polymer electrolytes. However, current composite polymer electrolytes (CPEs) are still facing challenges in Li metal batteries, falling short of inhibiting severe dendritic growth and resulting in very limited cycling life. This study introduces Ga 62.5 In 21.5 Sn 16 (Galinstan) liquid metal (LM) as an active liquid alternative to conventional passive solid fillers, aiming at realizing self‐healing protection against dendrite problems. Compared to solid inorganics, for example silica, LM droplets could more significantly reduce polymer crystallinity and enhance Li‐ion conductivity due to their liquid nature, especially at temperatures below the polymer melting point. More importantly, LMs are unraveled as dynamic chemical traps, which are capable of blocking and consuming lithium dendrites upon contact via in situ alloying during battery operation and further inhibiting dendritic growth due to the lower deposition energy barrier of the formed Li‐LM alloy. As a proof of concept, by strategically designing an asymmetric CPE with the active LM filling, a solid‐state Li/LiFePO 4 battery achieves promising full‐cell functionality with notable rate performance and stable cycle life. This active filler‐mediated self‐healing approach could bring new insights into the battery design in versatile solid‐state systems.

Wu, Kai↗
DOE OSTI2023

Anion-tethered Single Lithium-ion Conducting Polyelectrolytes through UV-induced Free Radical Polymerization for Improved Morphological Stability of Lithium Metal Anodes

Single Li + ion conducting polyelectrolytes (SICs), which feature covalently tethered counter-anions along their backbone, have the potential to mitigate dendrite formation by reducing concentration polarization and preventing salt depletion. However, due to their low ionic conductivity and complicated synthetic procedure, the successful validation of these claimed advantages in lithium metal (Li 0 ) anode batteries remains limited. In this study, we fabricated a SIC electrolyte using a single-step UV polymerization approach. The resulting electrolyte exhibited a high Li + transference number (t + ) of 0.85 and demonstrated good Li + conductivity (6.3×10 -5 S/cm at room temperature), which is comparable to that of a benchmark dual ion conductor (DIC, 9.1×10 -5 S/cm). Benefitting from the high transference number of SIC, it displayed a three-fold higher critical current density (2.4 mA/cm 2 ) compared to DIC (0.8 mA/cm 2 ) by successfully suppressing concentration polarization-induced short-circuiting. Additionally, the t + significantly influenced the deposition behavior of Li 0 , with SIC yielding a uniform, compact, and mosaic-like morphology, while the low t + DIC resulted in a porous morphology with Li 0 whiskers. In conclusion, using the SIC electrolyte, Li 0 ||LiFePO 4 cells exhibited stable operation for 4500 cycles with 70.5 % capacity retention at 22 °C.

25 ENERGY STORAGE↗
DOE OSTI2022

Stable and Recyclable Photocatalysts of CsPbBr 3 @MSNs Nanocomposites for Photoinduced Electron Transfer RAFT Polymerization

All-inorganic metal halide perovskite CsPbX 3 (X = Cl, Br, I) nanocrystals (NCs) have demonstrated attractive optoelectronic characteristics. However, their photocatalytic properties are limited by their poor stability and easy recombination of photogenerated carriers. Herein, we introduced a CsPbBr 3 @MSNs nanocomposite (CsPbBr 3 NCs embedded in dendritic mesoporous silica nanospheres (MSNs)) as photocatalysts for photoinduced electron transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization. In this study, the CsPbBr 3 nanocrystals (~8.1 nm; PLQY of 62 ± 2.1%) were embedded in dendritic MSNs using a nanoconfinement strategy. PET-RAFT polymerization was successfully initiated using the CsPbBr 3 @MSNs nanocomposite as the photocatalyst. Reaction variables, such as catalyst loading, monomer composition, and excitation light wavelengths, were varied to yield polymers with the desired control of molecular weight and dispersity as well as block copolymers with high chain-end fidelity. In addition, the perovskite-based photocatalysts could be readily separated and purified, which allowed effective and rapid recycling of the nanocomposites for multiple polymerization cycles.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2025

Regioisomeric Engineering for Multicharge and Spin Stabilization in Two-Electron Organic Catholytes

Developing multicharge and spin stabilization strategies is fundamental to enhancing the lifetime of functional organic materials, particularly for long-term energy storage in multiredox organic redox flow batteries. Current approaches are limited to the incorporation of electronic substituents to increase or decrease the overall electron density or bulky substituents to sterically shield reactive sites. With the aim to further expand the molecular toolbox for charge and spin stabilization, we introduce regioisomerism as a scaffold-diversifying design element that considers the collective and cumulative electronic and steric contributions from all of the substituents based on their relative regioisomeric arrangements. Through a systematic study of regioisomers of near-planar aromatic cyclic triindoles and nonplanar nonaromatic cyclic tetraindoles, we demonstrate that this regioisomeric engineering strategy significantly enhances the H-cell cycling stability in the above two new classes of 2e – catholytes, even when current strategies failed to stabilize the multicharged species. Density functional theory calculations reveal that the strategy operates by redistributing the charge and spin densities while highlighting the role of aromaticity in charge stabilization. The most stable 2e – catholyte candidate was paired with a viologen derivative anolyte to achieve a proof-of-concept all-organic flow battery with 1.26–1.49 V, 98% capacity retention, and only 0.0117% fade/h and 0.00563% fade/cycle over 400 cycles (192 h), which is the highest capacity retention ever reported over 400 cycles in a multielectron all-organic flow battery setup. We anticipate regioisomeric engineering to be a promising strategy complementary to conventional electronic and steric approaches for multicharge and spin stabilization in other functional organic materials.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2022

Novel Functional Thermal Energy Storage Materials for Buildings Applications

The leakage of solid-liquid phase change materials (PCMs) tremendously limits their long-term application in thermal energy storage (TES). In this work, we present durable and form-stable shape-stabilized PCMs (ss-PCMs) for TES in building envelopes. These ss-PCMs are fabricated by encapsulating polyethylene glycol (PEG) consisting of different molecular weights within mesoporous magnesium oxide and silica dioxide. For the first time, the phase transition temperature (Tt) of ss-PCMs has been fine-tuned synthetically to be comfortable to building occupants by utilizing PEG blends with molecular weights of 600 and 800 g/mol. Several parameters, including surface hydrophilicity/hydrophobicity, surface area, and PCM loading percentage, have been studied to maximize the latent heat enthalpy for high energy efficiency and maintain form stability. The best ss-PCM candidate with suitable Tt and appreciable latent heat enthalpy exhibits a repeatable phase change behavior for up to 1,000 thermal cycles without leakage, which provides a promising solution for durable TES in buildings. The Tt tunability extends its application over a wider temperature range beyond buildings.

building envelope↗