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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 OSTI2025

Probing the Impact of Vacancy Diffusion on Void Dynamics at the Lithium Metal–Solid Electrolyte Interface

Lithium (Li) metal-based solid-state batteries (SSBs) are considered promising candidates for next-generation energy storage due to their superior energy density and enhanced safety compared to conventional Li-ion systems. However, their practical application is limited by challenges such as void formation at the Li-solid electrolyte (SE) interface, which disrupts ion transport and accelerates interfacial degradation. This work investigates how the coupled effects of electro-dissolution kinetics and surface diffusion at the Li metal surface govern the evolution of interfacial morphology during stripping. This work examines the influence of three distinct surface diffusion modes, which are terrace diffusion, step diffusion, and interlayer diffusion, on maintaining interfacial stability. In addition, how the dominant surface diffusion mechanism can overcome the contact loss due to high reaction kinetics is explored. Furthermore, the roughness of the Li metal anode surface is quantified, and the influence of different diffusion mechanisms on the evolution of the dynamic solid–solid interface is examined. The critical role of temperature in enhancing Li surface diffusivity and expanding the regime of stable contact is highlighted. By identifying distinct regimes of interface stability, this study analyzes how non-uniform electrochemical dynamics dictate void morphology evolution and interfacial contact. These insights offer guiding principles for engineering robust Li–SE interfaces in SSBs.

lithium metal anode↗
NASA NTRS1995

Improved Preparation Of Solid-Electrolyte Films

Modified process ensures compatability among components. Improved chemical-blending procedure produces composite material for thin, large-area solid-electrolyte films for lithium batteries. Films have uniform compositions and dimensionally stable. Transport number of their lithium cations is high, close to unity. Batteries made with these films expected to have energy and power densities up to about 100 W h/kg and 100 W/kg, respectively. Previous version of composite material described in "Composite Solid Electrolyte for Lithium Cells" (NPO-18694).

Nagasubramanian, Ganesan↗
DOE OSTI2026

Structure-Dependent Lithium Metal Reactivity of Lithium Lanthanum Titanium Oxide Solid Electrolytes

Ongoing efforts to design stable, ionically conductive solid-state electrolytes (SSEs) for next-generation solid-state batteries make it clear that both long and short-range structural order strongly influence materials performance. However, clear structure-property relationships are generally lacking, making it difficult to develop design rules for improving the (electro) chemical stability of SSEs. Here, in this work, we synthesize epitaxial, single-crystal lithium lanthanum titanium oxide (LLTO) films and demonstrate that the kinetics of Ti 4+ reduction and lithium intercalation depend sensitively on the crystal orientation, with electrochemical stability increasing as LLTO (001) < (110) similar to (112) < (100). However, thermodynamic stability is ultimately unaffected-all orientations fully reduce after extended contact with Li metal. In contrast, amorphous LLTO films exhibit minimal, self-limiting reactivity that results in an interface that is stable to extended contact with Li metal. The results demonstrate the potential to engineer crystal lattice strain and long-range order to differentially tune the stability of the solid electrolyte toward reactive lithium metal and cathode materials, suggesting strategies for enabling the wider deployment of LLTO and other ionically conductive ceramic films in advanced energy storage technologies

Ketter, Benjamin [Argonne National Laboratory (ANL↗
DOE OSTI2022

A Solution-Processable High-Modulus Crystalline Artificial Solid Electrolyte Interphase for Practical Lithium Metal Batteries

The solid electrolyte interphase (SEI) has been identified as a key challenge for Li metal anodes. The brittle and inhomogeneous native SEI generated by parasitic reactions between Li and liquid electrolytes can devastate battery performance; therefore, artificial SEIs (ASEIs) have been proposed as an effective strategy to replace native SEIs. Herein, as a collaboration between academia and industrial R&D teams, a multifunctional (crystalline, high modulus, and robust, Li + ion conductive, electrolyte-blocking, and solution processable) ASEI material, LiAl-FBD (where “FBD” refers to 2,2,3,3-tetra-fluoro-1,4-butanediol), for improving Li metal battery performance is designed and synthesized. The LiAl-FBD crystal structure consists of Al 3+ ions bridged by FBD 2– ligands to form anion clusters while Li + ions are loosely bound at the periphery, enabling an Li + ion conductivity of 9.4 × 10 –6 S cm –1 . Further, the fluorinated, short ligands endow LiAl-FBD with electrolyte phobicity and high modulus. The ASEI is found to prevent side reactions and extend the cycle life of Li metal electrodes. Specifically, pairing LiAl-FBD coated 50 μm thick Li with industrial 3.5 mAh cm –2 NMC811 cathode and 2.8 μL mAh –1 lean elec-trolyte, the Li metal full cells show superior cycle life compared to bare ones, achieving 250 cycles at 1 mA cm –2 .

25 ENERGY STORAGE↗
DOE OSTI2026

Chemical and Structural Insights into Solid Electrolyte Interphase Evolution for Sodium Metal Electrodes

The solid electrolyte interphase (SEI) critically governs the reversibility of sodium metal batteries, through dynamically mediating ion transport and interfacial reactions. However, its kinetic evolution under operating conditions, and how it influences interfacial stability, remains poorly understood. Here, in this study, we reveal that the SEI undergoes coupled chemical and mechanical changes during sodium plating and stripping, leading to spatial and temporal heterogeneity that drives interfacial degradation. Synchrotron operando grazing-incidence wide-angle X-ray scattering and soft X-ray absorption spectroscopy capture the sequential formation and dissolution of inorganic SEI phases (NaF, NaH, NaOH, Na 2 PO 3 F), accompanied by depth-dependent alterations in organic SEI components. Mesoscale modeling connects this evolving SEI heterogeneity to localized current density fluctuations and stress accumulation at the Na interface, identifying pathways to electrically isolated sodium formation. These findings show that SEI instability fundamentally limits reversibility in sodium metal batteries, and that controlling SEI chemistry–mechanics coupling is essential to achieving its durability.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Surface treatment of a sulfide glass solid electrolyte layer

Chemically treating ionically conductive sulfide glass solid electrolyte separators or separator layers can improve performance. In particular, treatment involving chemically etching a surface or surface region of the sulfide glass separator to blunt, lessen or remove edge defects or surface flaws, and/or to enhance surface smoothness is cost effective, reliable and well suited for high production environments compared to physical methods of removing scratches or smoothing surfaces, such as mechanical grinding and polishing.

Visco, Steven J.↗
DOE OSTI2024

Ordered porous solid electrolyte structures, electrochemical devices with same, methods of making same

Provided are solid-state electrolyte structures. The solid-state electrolyte structures are ion-conducting materials. The solid-state electrolyte structures may be formed by 3-D printing using 3-D printable compositions. 3-D printable compositions may include ion-conducting materials and at least one dispersant, a binder, a plasticizer, or a solvent or any combination of one or more dispersant, binder, plasticizer, or solvent. The solid-state electrolyte structures can be used in electrochemical devices.

Wachsman, Eric D.↗
DOE OSTI2021

Mechanical studies of the solid electrolyte interphase on anodes in lithium and lithium ion batteries

A stable solid electrolyte interphase (SEI) layer is key to high performing lithium ion batteries for metrics such as calendar and cycle life. The SEI must be mechanically robust to withstand large volumetric changes in anode materials such as lithium and silicon, so understanding the mechanical properties and behavior of the SEI is essential for the rational design of artificial SEI and anode form factors. The mechanical properties and mechanical failure of the SEI are challenging to study, because the SEI is thin at only ~ 10 – 200 nm thick and is air sensitive. Furthermore, the SEI changes as a function of electrode material, electrolyte and additives, temperature, potential, and formation protocols. A variety of in situ and ex situ techniques have been used to study the mechanics of the SEI on a variety of lithium ion battery anode candidates; however, there hasn't been a succinct review of the findings thus far. Because of the difficultly of isolating the true SEI and its mechanical properties, there have been a limited number of studies that can fully de-convolute the SEI from the anode it forms on. A review of past research will be helpful for culminating current knowledge and helping to inspire new innovations to better quantify and understand the mechanical behavior of the SEI. This review will summarize the different experimental and theoretical techniques used to study the mechanics of SEI on common lithium ion battery anodes and their strengths and weaknesses.

25 ENERGY STORAGE↗
NASA NTRS2003

Annealing Would Improve beta" - Alumina Solid Electrolyte

A pre-operational annealing process is under investigation as a potential means of preventing a sudden reduction of ionic conductivity in a Beta"-alumina solid electrolyte (BASE) during use. On the basis of tests, the sudden reduction of ionic conductivity, followed by a slow recovery, has been found to occur during testing of the solid electrolyte and electrode components of an alkali metal thermal-to-electric converter (AMTEC) cell. At this time, high-temperature tests of limited duration have indicated the superiority of the treated BASE, but reproducible tests over thousands of hours are necessary to confirm that microcracking has been eliminated. The ionic conductivity of the treated BASE is also measured to be higher than untreated BASE at 1,073 K in low-pressure sodium vapor. Microcracking resulting in loss of conductivity was not observed with treated BASE in one high-temperature experiment, but this result must be duplicated over very long testing times to be sure of the effect. Shorter annealing times (10 to 20 hours) were found to result in significantly less loss of mass; it may be necessary for the packed powder mixture to evolve some Na2O before the Na2O can leave the ceramic.

Williams, Roger↗
NASA NTRS1973

Electromotive force measurements on cells involving beta-alumina solid electrolyte

Open circuit emf measurements have been made to demonstrate that a two-phase, polycrystalline mixture of beta- alumina and alpha-alumina could be used as a solid electrolyte in galvanic cells with reversible electrodes fixing oxygen or aluminum chemical potentials. These measurements indicate that such a two phase solid electrolyte can be used to monitor oxygen chemical potentials as low as that corresponding to Al, Al2O3 coexistence. The activity of Na2O in beta-alumina in coexistence with alpha-alumina was also determined by emf measurements.

Choudhury, N.↗
DOE OSTI2025

Temperature-dependent solid electrolyte interphase reactions drive performance in lithium-mediated nitrogen reduction to ammonia

The solid electrolyte interphase (SEI) is a vital component to control mass transport and selectivity in the lithium-mediated reduction of N 2 to NH 3 (Li-N 2 R). Finding strategies that generate the optimal SEI, a complex network of organic and inorganic species, can potentially improve Li-N 2 R performance. Here, we unravel structure-property relationships of the SEI by correlating its composition with the NH 3 faradaic efficiency (FENH3). By modifying the reaction temperature, we alter electrolyte decomposition reactions and observe changes in the SEI that explain FE NH3 trends between electrolyte solvents. We quantify a complex reaction environment at elevated temperatures where SEI formation is counteracted by etching reactions. This tradeoff leads to temporal fluctuations of FE NH3 , but the maximal FE NH3 can reach up to 40%, the highest value reported for batch cells at ambient pressure, thus far. In conclusion, our work underscores the potential of novel electrolytes that steer SEI selectivity and, ultimately, improve Li-N 2 R performance.

electrocatalytic nitrogen reduction↗
DOE OSTI2024

Self-terminating, heterogeneous solid–electrolyte interphase enables reversible Li–ether cointercalation in graphite anodes

Ether solvents are suitable for formulating solid-electrolyte interphase (SEI)-less ion-solvent cointercalation electrolytes in graphite for Na-ion and K-ion batteries. However, ether-based electrolytes have been historically perceived to cause exfoliation of graphite and cell failure in Li-ion batteries. In this study, we develop strategies to achieve reversible Li–solvent cointercalation in graphite through combining appropriate Li salts and ether solvents. Specifically, we design 1M LiBF 4 1,2-dimethoxyethane (G1), which enables natural graphite to deliver ~91% initial Coulombic efficiency and >88% capacity retention after 400 cycles. We captured the spatial distribution of LiF at various length scales and quantified its heterogeneity. The electrolyte shows self-terminated reactivity on graphite edge planes and results in a grainy, fluorinated pseudo-SEI. The molecular origin of the pseudo-SEI is elucidated by ab initio molecular dynamics (AIMD) simulations. The operando synchrotron analyses further demonstrate the reversible and monotonous phase transformation of cointercalated graphite. Our findings demonstrate the feasibility of Li cointercalation chemistry in graphite for extreme-condition batteries. The work also paves the foundation for understanding and modulating the interphase generated by ether electrolytes in a broad range of electrodes and batteries.

25 ENERGY STORAGE↗
DOE OSTI2021

Ion‐Conducting, Electron‐Blocking Layer for High‐Performance Solid Electrolytes

Lithium metal batteries bring greater promise for energy density, often relying on solid‐state electrolytes to meet critical benchmarks. However, Li dendrite formation is a prevailing problem that limits the cycle life and Coulombic efficiency of solid‐state Li metal batteries. For the first time, a thin (<100 nm) layer of electronically insulating, ionically conducting lithium phosphorus oxynitride (LiPON) is applied using atomic layer deposition between a Li anode and garnet Li 7 La 3 Zr 2 O 12 (LLZO). The performance of a conformal LiPON layer as an electron barrier in symmetric Li‐LLZO cells is observed through potential step chronoamperometry, galvanostatic cycling, electron microscopy, and various spectroscopic techniques. The LiPON‐coated LLZO achieves 100 times lower electronic conductance than LLZO alone. Cycling carried out at 0.1 mA cm −2 for 100 cycles demonstrates that suppression of electron pathways into the bulk solid electrolyte improves the cycle life of a lithium metal cell. These findings suggest an electronic conductivity effect in solid‐state electrolytes. A strategy is demonstrated to design thin‐film (LiPON)‐modulated bulk solid‐state electrolytes (LLZO) capable of maintaining high ionic conductivity and electrochemical stability while reducing the effective electronic conductivity, which results in significantly decreased dendrite formation, improved cycle life, and greater interfacial integrity between the electrolyte and a Li anode.

Hitz, Emily M.↗
NASA NTRS1973

Electromotive force measurements on cells involving beta-alumina solid electrolyte

Open-circuit emf measurements have been made to demonstrate that a two-phase, polycrystalline mixture of beta-alumina and alpha-alumina could be used as a solid electrolyte in galvanic cells with reversible electrodes fixing oxygen or aluminum chemical potentials. These measurements indicate that such a two-phase solid electrolyte may be used to monitor oxygen chemical potentials as low as that corresponding to Al and Al2O3 coexistence (potentials of about 10 to the minus 47th power atm at 1000 K). The activity of Na2O in beta-alumina in coexistence with alpha-alumina was also determined by emf measurements.

Choudhury, N. S.↗
DOE OSTI2023

Kinetic pathways of fast lithium transport in solid electrolyte interphases with discrete inorganic components

The transport of lithium ions in the solid electrolyte interphase (SEI) has been previously accepted to proceed in two steps: a fast pore diffusion through the outer, porous organic layer followed by a slow knock-off or vacancy diffusion in the inner, dense inorganic layer. The second step is believed to be the rate-limiting step during fast-charging. In this study, we have intentionally constructed a thicker SEI (SEI-rich) structure on the surface of monoclinic Nb 2 O 5 (H-Nb 2 O 5 ) by adding LiNO 3 into a conventional ethylene carbonate based electrolyte. The electrochemical performance of two electrodes, one SEI-rich and one with few SEI (SEI-lean), was found to be almost the same, including their fast-charging capability and cycling stability, despite the significant difference in their SEI structure. Importantly, analysis using cryogenic scanning/transmission electron microscopy showed the discrete decoration of individual inorganic particles (e.g., Li 2 O) and amorphous species (LiN x O y /organic components) over the surface of H-Nb 2 O 5 . These discrete inorganic particles are in contradiction to the formation of dense inner inorganic layer, which has been commonly postulated. Based on these findings, we propose a new mechanism for Li ion transport through the SEI: one-step pore diffusion, without the second step slow diffusion. This one-step pore diffusion process provides an extremely fast Li ion transport, and effectively removes the kinetic limitation of Li ion transport in the SEI for fast charging. Finally, these results strongly suggest that the influence of SEI structure on the transport kinetics of lithium ions is much less significant than previously accepted. These results offer a new understanding of possible lithium ion transport pathway within SEI and may have implications for the future designs of fast-charging battery materials.

25 ENERGY STORAGE↗