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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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Ion Conducting Polymer Interfaces for Lithium Metal Anodes: Impact on the Electrodeposition Kinetics

Electrochemical cells that utilize metals (e.g., lithium, sodium, zinc) as anodes are under intense investigation as they are projected to replace the current lithium-ion batteries to serve as a more energy-dense option for commercial applications. In addition, metal electrodes provide opportunities for fundamental research of different phenomena, such as ion transport and electrochemical kinetics, in the complex environment of reactive metal-electrodeposition. In this work, computationally and experimentally the competing effects related to transport and kinetics during the metal electrodeposition process are examined. Using Brownian dynamics simulations, it is shown that slower deposition kinetics results in a more compact and uniform Li morphology. This finding is experimentally implemented by designing ion-containing polymeric coatings on the electrodes that simultaneously provide pathways for lithium-ion transport, while impeding the charge transfer (Li + + e - → Li) at heterogeneous surfaces. It is further shown that these ionic polymer interfaces can significantly extend the cell-lifetime of a lithium metal battery in both ether-based and carbonate-based electrolytes. Through theoretical and experimental investigations, it is found that a low kinetic to transport rate ratio is a major factor in influencing the Li plating morphology. The plating morphology can be further fine-tuned by increasing ionic conductivity.

36 MATERIALS SCIENCE↗
DOE OSTI2020

A self-healing liquid metal anode with PEO-Based polymer electrolytes for rechargeable lithium batteries

In this study, a Ga-Sn liquid metal alloy material is demonstrated as a self-healing anode system due to its fluidity via operando synchrotron-based transmission X-ray microscopy and X-ray diffraction experiments. Cracks formed due to volume expansions can be recovered by the fluidity of the liquid metals. By incorporating with a poly(ethylene oxide) (PEO)-based electrolyte at 60°C, the Ga-Sn anode shows a reversible lithium insertion and extraction process with a high initial discharge specific capacity of 682 mAh g -1 , followed by delivering a capacity of 462 mAh g -1 in the second cycle at C/20 rate. Furthermore, compared with its solid counterparts, the Ga-Sn liquid metal anode demonstrates a better capability to maintain its mechanical integrity and better contact with PEO solid electrolytes due to its advantageous features of the liquid. This study suggests a potential strategy to use liquid metal alloys with polymer solid electrolyte to solve the anode challenges in rechargeable lithium batteries.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Highly reversible Zn metal anode enabled by sustainable hydroxyl chemistry

Rechargeable Zn metal batteries (RZMBs) may provide a more sustainable and lower-cost alternative to established battery technologies in meeting energy storage applications of the future. However, the most promising electrolytes for RZMBs are generally aqueous and require high concentrations of salt(s) to bring efficiencies toward commercially viable levels and mitigate water-originated parasitic reactions including hydrogen evolution and corrosion. Electrolytes based on nonaqueous solvents are promising for avoiding these issues, although full cell performance demonstrations with solvents other than water have been very limited. To address these challenges, we investigated MeOH as an alternative electrolyte solvent. These MeOH-based electrolytes exhibited exceptional Zn reversibility over a wide temperature range, with a Coulombic efficiency > 99.5% at 50% Zn utilization without cell short-circuit behavior for > 1,800 h. More important, this remarkable performance translates well to Zn || metal-free organic cathode full cells, supporting < 6% capacity decay after > 800 cycles at –40°C.

25 ENERGY STORAGE↗
DOE OSTI2022

Bi-metallic anode for amplitude modulated magnetron

An anode structure for a magnetron provides for low eddy currents and efficient water cooling. The anode structure may be made by machining a bimetal blank including an out layer of a first metal and an inner layer of a second metal and formed by explosion bonding. The second metal has a resistivity lower than first metal and a thermal conductivity higher than the first metal. The machining may result in the anode structure with vanes each having a center (tip) portion made of the second metal and the rest made of the first metal. The machined anode structure may be coated with the second metal.

Neubauer, Michael L.↗
DOE OSTI2024

Bi-metallic anode for amplitude modulated magnetron

An anode structure for a magnetron provides for low eddy currents and efficient water cooling. The anode structure may be made by machining a bimetal blank including an out layer of a first metal and an inner layer of a second metal and formed by explosion bonding. The second metal has a resistivity lower than first metal and a thermal conductivity higher than the first metal. The machining may result in the anode structure with vanes each having a center (tip) portion made of the second metal and the rest made of the first metal. The machined anode structure may be coated with the second metal.

Neubauer, Michael L.↗
DOE OSTI2025

Bi-metallic anode for amplitude modulated magnetron

An anode structure for a magnetron provides for low eddy currents and efficient water cooling. The anode structure may be made by machining a bimetal blank including an out layer of a first metal and an inner layer of a second metal and formed by explosion bonding. The second metal has a resistivity lower than first metal and a thermal conductivity higher than the first metal. The machining may result in the anode structure with vanes each having a center (tip) portion made of the second metal and the rest made of the first metal. The machined anode structure may be coated with the second metal.

Neubauer, Michael L.↗
DOE OSTI2023

Calcium Cosalt Addition to Alter the Cation Solvation Structure and Enhance the Ca Metal Anode Performance

Accessing the energy density and sustainability of calcium metal batteries requires mastering reversible calcium electrodeposition through electrolyte design. Several electrolytes support reversible, ambient temperature deposition but at utilization and rate too low for practical applications. These challenges stem from solvation structures characterized by either high barriers for cation desolvation or thermodynamic instability, leading to parasitic decomposition of the salt and solvent. The optimal solvation structure for the effective delivery of calcium to the electrode interface is not known. In this work, we show that adding a relatively small amount of a weakly associating calcium salt (calcium carba-closo-dodecaborate) to an otherwise strongly associated solution (calcium borohydride in tetrahydrofuran) produces a surprising population of fully solvent-coordinated Ca2+ cations in the form of solvent-separated ion pairs (SSIPs). We further demonstrate that the formation of these SSIPs beneficially impacts the kinetics and thermodynamics of calcium electrodeposition, revealing the unexpected finding that direct coordination of Ca2+ by the BH4– anion limits the electrodeposition process. These findings reveal how the competition between solvent and anion coordination to Ca2+ affects calcium deposition kinetics and cycling stability, setting the stage for a new calcium electrolyte design based on mixed anion electrolytes.

Landers, Alan T.↗
DOE OSTI2024

Interdependence of Support Wettability ‐ Electrodeposition Rate‐ Sodium Metal Anode and SEI Microstructure

Abstract This study examines how current collector support chemistry (sodiophilic intermetallic Na 2 Te vs. sodiophobic baseline Cu) and electrodeposition rate affect microstructure of sodium metal and its solid electrolyte interphase (SEI). Capacity and current (6 mAh cm −2 , 0.5–3 mA cm −2 ) representative of commercially relevant mass loading in anode‐free sodium metal battery (AF‐SMBs) are analyzed. Synchrotron X‐ray nanotomography and grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) are combined with cryogenic ion beam (cryo‐FIB) microscopy. Highlighted are major differences in film morphology, internal porosity, and crystallographic preferred orientation e.g. (110) vs. (100) and (211) with support and deposition rate. Within the SEI, sodium fluoride (NaF) is more prevalent with Te−Cu versus sodium hydride (NaH) and sodium hydroxide (NaOH) with baseline Cu. Due to competitive grain growth the preferred orientation of sodium crystallites depends on film thickness. Mesoscale modeling delineates the role of SEI (ionic conductivity, morphology) on electrodeposit growth and onset of electrochemical instability.

Lo, Chang‐An↗
DOE OSTI2025

Enhanced Reversibility of Iron Metal Anode with a Solid Electrolyte Interphase in Concentrated Chloride Electrolytes

Iron is a promising candidate for a cost-effective anode for large-scale energy storage systems due to its natural abundance and well-established mass production. Recently, Fe-ion batteries (FeIBs) that use ferrous ions as the charge carrier have emerged as a potential storage solution. The electrolytes in FeIBs are necessarily acidic to render the ferrous ions more anodically stable, allowing a wide operation voltage window. However, the iron anode suffers severe hydrogen evolution reaction with a low Coulombic efficiency (CE) in an acidic environment, shortening the battery cycle life. Herein, a hybrid aqueous electrolyte that forms a solid-electrolyte interphase (SEI) layer on the Fe anode surface is introduced. The electrolyte mainly comprises FeCl 2 and ZnCl 2 as cosalts, where the Zn-Cl anionic complex species of the concentrated ZnCl 2 allows dimethyl carbonate (DMC) to be miscible with the aqueous ferrous electrolyte. SEI derived from DMC's decomposition passivates the iron surface, which leads to an average CE of 98.3% and much-improved cycling stability. As a result, this advancement shows the promise of efficient and durable FeIBs.

25 ENERGY STORAGE↗
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 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 OSTI2023

Data-driven electrolyte design for lithium metal anodes

Improving Coulombic efficiency (CE) is key to the adoption of high energy density lithium metal batteries. Liquid electrolyte engineering has emerged as a promising strategy for improving the CE of lithium metal batteries, but its complexity renders the performance prediction and design of electrolytes challenging. Here, we develop machine learning (ML) models that assist and accelerate the design of high-performance electrolytes. Using the elemental composition of electrolytes as the features of our models, we apply linear regression, random forest, and bagging models to identify the critical features for predicting CE. Our models reveal that a reduction in the solvent oxygen content is critical for superior CE. We use the ML models to design electrolyte formulations with fluorine-free solvents that achieve a high CE of 99.70%. This work highlights the promise of data-driven approaches that can accelerate the design of high-performance electrolytes for lithium metal batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Elucidating Interfacial Stability between Lithium Metal Anode and Li Phosphorus Oxynitride via In Situ Electron Microscopy

Li phosphorus oxynitride (LiPON) is one of a very few solid electrolytes that have demonstrated high stability against Li metal and extended cyclability with high Coulombic efficiency for all solid-state batteries (ASSBs). However, theoretical calculations show that LiPON reacts with Li metal. Here, we utilize in situ electron microscopy to observe the dynamic evolutions at the LiPON–Li interface upon contacting and under biasing. We reveal that a thin interface layer (~60 nm) develops at the LiPON–Li interface upon contact. This layer is composed of conductive binary compounds that show a unique spatial distribution that warrants an electrochemical stability of the interface, serving as an effective passivation layer. Our results explicate the excellent cyclability of LiPON and reconcile the existing debates regarding the stability of the LiPON–Li interface, demonstrating that, though glassy solid electrolytes may not have a perfect initial electrochemical window with Li metal, they may excel in future applications for ASSBs.

25 ENERGY STORAGE↗
DOE OSTI2023

Intermetallics Based on Sodium Chalcogenides Promote Stable Electrodeposition–Electrodissolution of Sodium Metal Anodes

Sodiophilic micro-composite films of sodium-chalcogenide intermetallics (Na 2 Te and Na 2 S) and Cu particles are fabricated onto commercial copper foam current collectors (Na 2 Te@CF and Na 2 S@CF). For the first time a controllable capacity thermal infusion process is demonstrated. Enhanced wetting by the metal electrodeposition leads to state-of-the-art electrochemical performance. For example, Na 2 Te@CF-based half-cells demonstrate stable cycling at 6 mA cm -2 and 6 mAh cm -2 , corresponding to 54 µm of Na electrodeposited/electrodissolved by geometric area. Sodium metal batteries with Na 3 V 2 (PO 4 ) 3 cathodes are stable at 30C (7 mA cm -2 ) and for 10 000 cycles at 5C and 10C. Cross-sectional cryogenic focused ion beam (cryo-FIB) microscopy details deposited and remnant dissolved microstructures. Sodium metal electrodeposition onto Na 2 Te@CF is dense, smooth, and free of dendrites or pores. On unmodified copper foam, sodium grows in a filament-like manner, not requiring cycling to achieve this geometry. Substrate–metal interaction critically affects the metal–electrolyte interface, namely the thickness and morphology of the solid electrolyte interphase. Density functional theory and mesoscale simulations provide insight into support-adatom energetics, nucleation response, and early-stage morphological evolution. On Na 2 Te sodium atomic dispersion is thermodynamically more stable than isolated clusters, leading to conformal adatom coverage of the surface.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Ternary Potassium‐Bismuth‐Telluride Intermetallic Support Promotes Electrochemical Stability in Potassium Metal Anodes

We employed accumulative roll bonding to fabricate self‐standing metallurgical composite of in situ formed alkaline potassium‐bismuth‐telluride intermetallic K 2 (Bi 2/6 Te 3/6 Vac 1/6 ) embedded in potassium metal. This newly discovered thermodynamically stable potassiophilic crystal, termed “KBT”, is fcc antifluorite with K 2 Te archetype. Symmetric cells achieve 880 h of cycling at 0.5 mA cm −2 and 0.5 mAh cm −2 . Potassium metal battery (KMB) with Prussian blue (PB) cathode in carbonate electrolyte retains 80% capacity after 200 cycles at 1C. In ether‐based electrolyte with organic cathode, it achieves 80% retention after 900 cycles at 2C. Combined synchrotron X‐ray nano‐tomography, cryogenic‐focused ion beam microscopy (Cryo‐FIB) and sputter‐down X‐ray photoelectron spectroscopy (XPS) demonstrate uniform electrodeposits, versus baseline of potassium filaments intermixed with pores and coarse SEI. Binary K 3 Bi‐K and K 2 Te‐K intermetallic supports also provide improved electrochemical performance, albeit to lesser extent. Multiscale simulation provides insight into role of support structure in adatom energetics, film nucleation, early‐stage SEI morphology and interfacial stability.

36 MATERIALS SCIENCE↗