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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 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

Aliovalent Anion Incorporation in Halide Na-ion Conductors for Enhanced Ionic Conductivity

Halide-based solid electrolytes (SEs), particularly zirconium (Zr)-centered halides, are attractive from a material cost perspective. Nevertheless, Zr-centered halide SEs are hindered by their low ionic conductivity. Here, in this study, we report on the cubic Na 3 ZrCl 5 S superionic conductor through strategic sulfur anion incorporation, achieving 10 times higher ionic conductivity than that of Na 2 ZrCl 6 . With the optimal composition, the highest ionic conductivity of 0.753 mS cm –1 is obtained for the 0.6Na 2 S–1.4NaCl–ZrCl 4 compound. When paired with a NaCrO 2 cathode, the assembled all-solid-state batteries (ASSBs) achieve a specific discharge capacity of 110 mA h g –1 at 0.1C and exhibit long-term cycling stability at 0.3C at room temperature over 1000 cycles (with 83% capacity retention). Moreover, in situ electrochemical impedance spectroscopy combined with distribution of relaxation times analysis reveal the dynamically interfacial stability between Na halide with electrodes. In conclusion, this work highlights the design and synthesis of advanced halide electrolytes through anion incorporation, paving the way for the development of next-generation ASSBs.

Guo, Xiaolin [Univ. of Louisville, KY (United Stat↗
NASA NTRS1986

A universal equation of state for solids

The total energy versus interatomic spacing of ionic, metallic, covalent, and rare-gas solids is examined, and a universal form for pressure as a function of volume for all classes of solids in compression is derived. The relation is shown to hold for pressure-volume data for hydrogen and deuterium, xenon, cesium, molybdenum, sodium chloride, and magnesium oxide.

Vinet, P.↗
NASA NTRS1976

Applications of beam-foil spectroscopy to atomic collisions in solids

Some selected papers presented at the Fourth International Conference on Beam-Foil Spectroscopy, whose results are of particular pertinence to ionic collision phenomena in solids, are reviewed. The topics discussed include solid target effects and means of surmounting them in the measurement of excited projectile ion lifetimes for low-energy heavy element ions; the electron emission accompanying the passage of heavy particles through solid targets; the collision broadening of X rays emitted from 100 keV ions moving in solids; residual K-shell excitation in chlorine ions penetrating carbon; comparison between 40 MeV Si on gaseous SiH4 targets at 300 mtorr and 40 MeV Si on Al; and the emergent surface interaction in beam-foil spectroscopy. A distinct overlap of interests between the sciences of beam-foil spectroscopy and atomic collisions in solids is pointed out.

Sellin, I. A.↗
DOE OSTI2025

Overcoming misconceptions in lithium metal polymer electrolyte batteries

Uncovering the truth of lithium polymer batteries. Lithium metal is the holy grail of anodes due to its 10-fold higher gravimetric capacity than graphite. All-solid-state lithium polymer electrolyte batteries are receiving significant attention due to their increased flexibility compared to inorganic solid-state electrolytes, which enhances processability, accommodates cell swelling, and enables more homogeneous interphases. However, prototype solid-state lithium polymer electrolyte batteries have been limited in their usage due to the low ionic conductivity of the electrolyte, which limits their ability to cycle lithium metal at high rates. In this opinion, we provide alternative interpretations of high-rate capability lithium metal polymer electrolytes and breakthroughs in highly ionically conductive all-solid-state polymer electrolytes. In addition, we provide guidance on how to characterize and evaluate polymer electrolytes in lithium metal batteries.

Waugh, John B↗
DOE OSTI2024

Sliceable, Moldable, and Highly Conductive Electrolytes for All-Solid-State Batteries

All-solid-state batteries (ASSBs) require solid electrolytes with high ionic conductivity, stability, and deformability for optimal energy and power density. Here, we developed lithium-deficient lithium yttrium bromide (LYB) solid electrolytes, Li 3–x YBr 6–x (0 ≤ x ≤ 0.50), using a comelting method with controlled lithium deficiency. These electrolytes exhibit favorable mechanical properties such as high moldability and sliceability. The Li 2.65 YBr 5.65 composition has an ionic conductivity of 4.49 mS cm –1 at 25 °C and an activation energy of 0.28 eV. Compared to Li 3 YBr 6 , Li 2.65 YBr 5.65 demonstrates improved rate performance and cycling stability in ASSBs. High-resolution X-ray diffraction confirms the formation of the LYB phase with a C2/m space group. Structural analysis reveals increased cation disorder and larger polyhedral volumes for x > 0 in Li 3–x YBr 6–x , contributing to reduced Li + migration energy barriers. Bond valence site energy calculations and molecular dynamics simulations reveal enhanced 3D lithium-ion transport. NMR spectroscopy further highlights increased Li + dynamics and impurity elimination.

Poudel, Tej P. [Florida State Univ., Tallahassee, ↗
DOE OSTI2024

The Key Role of Grain Boundary Dynamics in Revolutionizing the Potential of Solid Electrolytes

Solid electrolytes (SEs) have the potential to enhance the safety and performance of Li-metal batteries. However, the existence of grain boundaries in polycrystalline SEs presents a significant challenge for both ionic and electronic migration, promoting the propagation of detrimental lithium dendrites. This study compares the roles of grain boundaries in electrical properties of three distinct SEs including garnet-type Li 6.5 La 3 Zr 1.5 Ta 0.5 O 12 (LLZO), argyrodite-type Li 6 PS 5 Cl (LPSC), and NASICON-type Li 1+x+y Al x (Ti,Ge) 2-x Si y P 3-y O 12 (LATP). Results demonstrate that the electronic and ionic conductivities of solid-state electrolytes are affected differently by grain boundaries, depending on the specific type of electrolyte. For instance, LLZO and LATP experience dielectric breakdown at 3.7 and 5.3 V, respectively, while LPSC does not exhibit such behavior. Here, a new chemical modification is proposed that simultaneously alters the composition of both the surface and grain boundaries of SEs, ultimately reducing electronic conductivity for the LLZO SEs. Consequently, the proposed LLZO exhibits unprecedented dendrite-free cycling stability, achieving a remarkable 12 000-h lifetime at room temperature, surpassing conventional strategies such as surface coatings in dendrite mitigation. This study highlights the significance of modifying grain boundaries to design safe and durable Li-metal batteries. It provides new insights for developing SEs that are highly resistant to dendrite formation.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Extraction and Separation of Rare-Earth Elements from Coal Fly Ash and Leachate using a Recyclable Ionic Liquid

Coal fly ash (CFA) can be a promising source for recovering rare-earth elements (REEs), as it contains a broad range of REEs with average concentrations frequently exceeding those in traditional rare earth mines. Recent research from our group has demonstrated that REEs can be preferentially extracted from CFA solids using a recyclable ionic liquid (IL), betainium bis-(trifluoromethylsulfonyl)imide ([Hbet][Tf2N]). When CFA was heated with the mixture of IL and an aqueous solution above 65°C, most leached REEs partitioned into the IL phase and were separated from the bulk elements. Subsequent acid stripping of the REE-loaded IL removed the REEs and regenerated the IL for reuse in multiple extraction cycles. This IL-based REE-CFA recovery method has been applied to ten CFA samples derived from different coal sources, including ash recovered from disposal ponds. Analysis of 34 elements confirmed the process consistently achieved high REE recovery efficiency, with strong selectivity over bulk and trace elements across diverse CFA types. In addition to the IL-solid extraction, the performance of [Hbet][Tf2N] in extracting REEs from fly-ash leachates have been evaluated by four commonly used leaching reagents, including HCl, HNO3, H2SO4, and citrate. During the IL-leachate extraction, [Hbet][Tf2N] was mixed and heated with a Class C fly ash leachate generated from each leaching reagent, followed by an acid stripping. It was observed that the partitioning and recovery of REEs increased as the leachate pH increased from 3 to 11. Among the investigated leachates, HCl and citrate proved to be the most compatible with IL extraction, exhibiting a slightly higher REE recovery and a lower non-REE co-extraction compared to the IL-solid extraction. Sc, Y, Nd, Sm, Gd, Dy, and Yb consistently showed a high recovery rate from both CFA solids and leachates. Notably, Pr, Tb, and Ho, which were not previously leached from the CFA solids, were partially recovered from the leachates. Overall, our studies revealed the strong potential of [Hbet][Tf2N] for effectively recovering REEs from leachates, highlighting its applicability as a sustainable strategy for other aqueous REE feedstocks. Furthermore, a techno-economic analysis will be performed to quantify the economic viability of the IL-based REE recovery method and guide future process improvement.

42 ENGINEERING↗
DOE OSTI2025

Synthesis and post-heating treatment of inorganic NaF·Na 3 SbS 4 solid electrolytes

Sulfide-type sodium (Na) solid electrolytes (SEs) with halide doping have attracted serious interest due to their high ionic conductivity and great potential in solid-state Na batteries. While other halogens such as Cl, Br, I have been studied to enhance Na-ion transport in sulfide-type SEs, the introduction of fluorine (F) is rarely investigated. Moreover, synthetic parameters such as heating treatment temperatures strongly influence the structure and conductive properties of halide-doped sulfide SEs. Herein, we prepared xNaF·(1-x)Na 3 SbS 4 nanocomposites with varying concentration of F using a low-temperature (150 °C) heating method, and studied the effects of post-heating treatment on structure and conductivity. In-situ neutron diffraction was employed to investigate the structural evolution of X-doped Na 3 SbS 4 (X = F, Cl) during the post-heating treatment and cooling process. In addition, the post-heating treatment at 300 °C leads to increased ionic conductivity of xNaF·(1-x)Na 3 SbS 4 nanocomposites with various F contents. After 300 °C post-heating treatment, 0.2NaF·0.8Na 3 SbS 4 exhibited the highest conductivity of 0.48 mS cm –1 at room temperature. Moreover, improved electrochemical stability was also observed in Na-Sn symmetric cells, specially, with prolonged stable cycling for 300 h and much lower polarization voltage (<0.35 V). Furthermore, this work highlights the importance of post-heating treatment on the structural evolution and its role in exploring new halide-incorporated sulfide-type SEs, promoting the development of inorganic solid-state ionic conductors.

25 ENERGY STORAGE↗
DOE OSTI2025

The Dynamical Role of Optical Phonons and Sublattice Screening in a Solid-State Ion Conductor

Solid-state electrolytes (SSEs) require ionic conductivities that are competitive with liquid electrolytes to realize applications in all-solid-state batteries. Although candidate SSEs have been discovered, the underlying mechanisms enabling superionic conduction (>1 mS cm –1 ) remain elusive. In particular, the role of ultrafast lattice dynamics in mediating ion migration, which involves couplings between ions, phonons, and electrons, is rarely explored experimentally at their corresponding time scales. To investigate the complex contributions of coupled lattice dynamics on ion migration, we modulate the charge density occupations within the crystal framework and then measure the time-resolved change in impedance on picosecond time scales for a candidate SSE, Li 0.5 La 0.5 TiO 3 (LLTO). Upon perturbation, we observe enhanced ion migration at ultrafast time scales. The respective transients match the time scales of optical and acoustic phonon vibrations, suggesting their involvement in ion migration. We further computationally evaluate the effect of a charge transfer from the O 2p to the Ti 3d band on the electronic and physical structure of LLTO. We hypothesize that the charge-transfer excitation distorts the TiO 6 polyhedra by altering the local charge density occupancy of the hopping site at the migration pathway saddle point, thereby causing a reduction in the migration barrier for the Li + hop. We rule out the contribution of photogenerated electron carriers and laser heating. Overall, our investigation introduces a new spectroscopic tool to probe fundamental ion hopping mechanisms transiently at ultrafast time scales, which has previously only been achieved in a time-averaged manner or solely via computational methods.

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

Harnessing Cation Disorder for Enhancing Ionic Conductivity in Lithium Inverse Spinel Halides

Halides are promising solid-state electrolytes for all-solid-state lithium batteries due to their exceptional oxidation stability, high Li-ion conductivity, and mechanical deformability. However, their practicality is limited by the reliance on rare and expensive metals. This study investigates the Li 2 MgCl 4 inverse spinel system as a cost-effective alternative. Molecular dynamics simulations reveal that lithium disordering at elevated temperatures significantly reduces the activation energy in Li 2 MgCl 4 . To stabilize this disorder at lower temperatures, we experimentally explored the Li x Zr 1–x/2 Mg x/2 Cl 4 system and found that Zr doping induces both Zr and Li disorder at the 16c site at room temperature (RT). This leads to a 2 order-of-magnitude increase in ionic conductivity for the Li 1.25 Zr 0.375 Mg 0.625 Cl 4 composition, achieving 1.4 × 10 –5 S cm –1 at RT, compared to pristine Li 2 MgCl 4 . By deconvoluting the role of lithium vacancies and dopants, we reveal that cation disordering to the 16c site predominantly enhances ionic conductivity, whereas lithium vacancy concentration has a very limited effect.

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

The ion-ion correlations in organic ionic plastic crystal

Organic ionic plastic crystals (OIPCs) are emerging as promising electrolyte materials for solid-state batteries. However, despite the fast ionic diffusion, OIPCs exhibit relatively low DC conductivity in solid phases caused by strong ion-ion correlations that suppress charge transport. To understand the origin of this suppression, we performed a study of ion dynamics in the OIPC 1-Ethyl-1-methylpyrrolidinium bis (trifluoromethyl sulfonyl) imide [P 12 ][TFSI] utilizing dielectric spectroscopy, light scattering, and Nuclear Magnetic Resonance diffusometry. Comparison of the results obtained in this study with the published earlier results on an OIPC with a completely different structure (Diethyl(methyl)(isobutyl)phosphonium Hexafluorophosphate [P 1,2,2,4 ][PF 6 ]) revealed strong similarities in ion dynamics in both systems. Unlike DC conductivity, which may drop more than ten times between melted and solid phases, diffusion of anions and cations remains high and does not show strong changes at phase transition. The conductivity spectra in the broad frequency range demonstrate unusual shapes in solid phases with an additional step separating fast local ion motions from suppressed long-range charge diffusion controlling DC conductivity. We suggested that in solid phases, anions and cations can jump only between the specific ion sites defined by the crystalline structure. These constraints lead to strong cation-cation and anion-anion correlations strongly suppressing long-range charge transport.

36 MATERIALS SCIENCE↗
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 OSTI2025

Improving Ionic Conformality Across Polymer Electrolyte|Electrode Interfaces

Maintaining uniform ionic transport at electrode|electrolyte interfaces, i.e., ionic conformality, remains challenging in polymer electrolyte (PE)-based solid-state batteries. Morphological conformality does not necessarily imply ionic conformality. In PEs, which typically consist of a mechanically supporting component and distinct ionically conductive components, the rearrangement or depletion of mobile ion-conductive domains at interfaces can disrupt ionic transport pathways. Such localized ionic depletion contributes to interfacial instability and capacity degradation in high-voltage lithium-metal batteries. Herein, an electrolyte design approach aimed at minimizing interfacial heterogeneities is demonstrated through compositional adjustments, characterized by spatially resolved structural and chemical X-ray techniques and NMR diffusometry to elucidate ion transport dynamics. This approach improves ionic conformality at electrode interfaces, enhancing cycling stability in Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NMC811) coin and pouch cells cycled at high voltages. These results contribute to understanding interfacial behaviors in multiphase PEs and inform strategies for improving stability across solid-state battery interfaces.

36 MATERIALS SCIENCE↗
NASA NTRSDate not supplied

Interpretable Tree-Based and Graph Neural Network Approaches for Novel Solid State Electrolyte Design

All-solid-state batteries with Li metal anode can address the safety issues surrounding traditional Li-ion batteries as well as the demand for higher energy densities. However, the development of solid electrolytes simultaneously possessing high ionic conductivity and good chemical and electrochemical stabilities has proven to be a challenge. I will present our informatics approach to explore the Li compound space for promising solid electrolytes using high-throughput multi-property screening and interpretable machine learning. This is accomplished through the generation of a large database of battery-related materials properties of Li compounds. We use tree-based ensemble learning methods and graph neural network approaches to accurately learn relationships between crystal structures and corresponding thermodynamic and kinetic properties, with interpretability being a major focus. Our models give us the ability to enable rapid discovery and design of novel solid-state battery chemistries.

Materials discovery↗
NASA NTRSDate not supplied

Interpretable ML Approaches for Novel Solid State Electrolyte Design

All-solid-state batteries with Li metal anode can address the safety issues surrounding traditional Li-ion batteries as well as the demand for higher energy densities. However, the development of solid electrolytes simultaneously possessing high ionic conductivity and good chemical and electrochemical stabilities has proven to be a challenge. I will present our informatics approach to explore the Li compound space for promising solid electrolytes using high-throughput multi-property screening and interpretable machine learning. This is accomplished through the generation of a large database of battery-related materials properties of Li compounds. We use tree-based ensemble learning methods and graph neural network approaches to accurately learn relationships between crystal structures and corresponding thermodynamic and kinetic properties, with interpretability being a major focus. Our models give us the ability to enable rapid discovery and design of novel solid-state battery chemistries.

Shreyas J Honrao↗
DOE OSTI2025

Chemical Bond Covalency in Superionic Halide Solid‐State Electrolytes

Abstract Halide solid‐state electrolytes (SSEs) are promising superionic conductors with high oxidative stability and ionic conductivity, making them attractive for all‐solid‐state lithium‐ion batteries. However, most studies have focused on ion‐stacking structures, overlooking the role of bond characteristics in ionic transport. Here, we investigate bond dynamics and the superionic transition (SIT) in bromide electrolyte, Li 3 InBr 6 , using synchrotron X‐ray techniques and ab initio molecular dynamics (AIMD) simulations. We demonstrate that the SIT in halide SSEs is driven by a thermally induced transition in bonding character (ionic to covalent) rather than a change in crystal phase. AIMD simulations further reveal enhanced Li⁺ diffusion and collective anion motion at elevated temperatures. Expanding our study to Li 3 LnBr 6 (Ln = Gd, Tb, Ho, Tm, and Lu), we confirm the widespread occurrence of SIT in this material class, with Li 3 GdBr 6 exhibiting the highest ionic conductivity (5.2 mS cm −1 at 298 K). More importantly, the ionic‐covalent transition is highly tunable through electrolyte modifications, such as cation/anion substitution and synthesis methods. Our findings provide a new perspective on ionic transport, highlighting the critical role of chemical bond characteristics in halide SSEs.

Chemistry↗