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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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Lithium halide cathodes for Li metal batteries

Lithium halides cathodes potentially offer a high energy density at a low cost for rechargeable batteries. However, these cathodes suffer from quick capacity decay in organic electrolytes and the failiure mechanism remains elusive. Here, we report that liquefying the halogen or interhalogen compounds is a prerequisite for achieving high reversibility for the lithium halides cathodes. The gas or solid halogen can be liquefied by using interhalogen compounds with different electronegativity or changing the temperature. As a proof of concept, reversible LiCl conversion-intercalation chemistry in organic electrolyte is demonstrated by using either redox coupling with less electronegative I/Br to form liquid ICl/BrCl or reducing the temperature to -30oC. Further, the LiCl-LiBr-graphite cathodes in 1.6M lithium difluoro(oxalato)borate/1.6M lithium triflate in diglyme electrolytes achieve a high reversible specific capacity of 250 mAh/g at 3.7 V with an energy density being comparable to or higher than transition metal oxide cathodes at a much lower cost.

25 ENERGY STORAGE↗
DOE OSTI2022

Thermodynamic assessment of lithium halide reciprocal salt systems for energy applications

Lithium halides are of interest because of their unique applications as fuel or coolants in molten salt reactors (MSRs) and electrolytes in thermally activated batteries. Because iodine is an important fission product for MSRs, the Molten Salt Thermal Properties Database-Thermochemical (MSTDB-TC) is being expanded to include relevant iodide reciprocal salt systems. In this work, we assess the thermochemical properties of lithium halide pseudobinary systems based on reported experimental phase diagrams, eutectic temperatures, and enthalpies of mixing. Within the framework of the modified quasi-chemical model in the quadruplet approximation (MQMQA), extrapolations to the related pseudoternary and pseudoquaternary systems have been performed. The pseudoquaternary representations of phase equilibria, enthalpy, entropy, and heat capacity are represented in the resultant models. Of interest for generating source terms for accident analysis is the ability to compute the vapor pressures of the dominant iodide species for the systems at any composition. Here, an example of such calculations is provided for the LiF-LiI system at x LiI = 0.01 and x LiI = 0.70, in this case indicating that the LiI vapor species are predominant.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Designing lithium halide solid electrolytes

All-solid-state lithium batteries have attracted widespread attention for next-generation energy storage, potentially providing enhanced safety and cycling stability. The performance of such batteries relies on solid electrolyte materials; hence many structures/phases are being investigated with increasing compositional complexity. Among the various solid electrolytes, lithium halides show promising ionic conductivity and cathode compatibility, however, there are no effective guidelines when moving toward complex compositions that go beyond ab -initio modeling. Here, we show that ionic potential, the ratio of charge number and ion radius, can effectively capture the key interactions within halide materials, making it possible to guide the design of the representative crystal structures. This is demonstrated by the preparation of a family of complex layered halides that combine an enhanced conductivity with a favorable isometric morphology, induced by the high configurational entropy. This work provides insights into the characteristics of complex halide phases and presents a methodology for designing solid materials.

25 ENERGY STORAGE↗
DOE OSTI2020

Fast Li-Ion Conductivity in Superadamantanoid Lithium Thioborate Halides

Lithium thioborates are promising fast Li-ion conducting materials, with similar properties to their lithium thiophosphate counterparts that have enabled the development of solid-state Li-ion batteries. By comparison, thioborates have scarcely been developed, however, offering new space for materials discovery. In this work, we report a new class of lithium thioborate halides that adopt a so-called supertetrahedral adamantanoid structure that houses mobile lithium ions and halide anions within interconnected 3D structural channels. Investigation of the structure using single-crystal XRD, neutron powder diffraction, and neutron PDF reveals significant lithium and halide anion disorder. The phases are non-stoichiometric, adopting slightly varying halide contents within the materials. These new superadamantanoid materials exhibit high ionic conductivities up to 1.4 mS cm -1 , which can be effectively tuned by the polarizability of the halide anion within the channels.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Thermodynamic and Kinetic Barriers Limiting Solid-State Reactions Resolved through In Situ Synchrotron Studies of Lithium Halide Salts

Although halide salts such as LiCl and LiBr are routinely used as a source of Li ions during ion exchange reactions, a detailed understanding of the processes controlling the rates of these reactions is presently lacking. Recently, it has been discovered that the rate limiting barriers for ion exchange are commonly associated with these salts rather than the ceramic target of ion exchange, making it important to quantitatively understand of salt processes. Here it is demonstrated that in situ synchrotron studies of ion exchange reactions can be used to precisely quantify the thermodynamic activation energies associated with these solid state reactions in a manner that can be directly compared with predictions from density functional theory (DFT). While the temperature dependence of the LiCl reaction rate is found to be set by a barrier associated with ion hopping, it was discovered that for LiBr it is also affected by the defect formation energy – an energy found to be substantially lower than predicted by DFT. Furthermore, it is shown that when reaction rates for different relative amounts of reactants are varied, it is possible to identify the rate-limiting reagent and to elucidate an overall scaling relationship that controls the concentration-dependence of the reaction rate. Also, it is demonstrated that global fits across doped and undoped salts can be used to probe both intrinsic and extrinsic vacancy concentrations. This improved understanding of ion exchange mechanisms can be used to accelerate ion exchange reaction rates by orders of magnitude. In conclusion, the techniques demonstrated here can be broadly applied to probe the kinetics and thermodynamics of solid state reactions.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Phase evolution during lithium–indium halide superionic conductor dehydration

Select rare-earth alkali halides have demonstrated high lithium ion conductivity. The conductivity appears to be related to the stability of the crystal phase, ordering of the lithium sublattice and the amount of residual H 2 O. Li 3 InCl 6 can be synthesized from concentrated aqueous solution through controlled dehydration. In this work, we track Li 3 InCl 6 dehydration using a multimodal approach that combines thermogravimetric, spectroscopic, X-ray diffraction, and neutron scattering techniques. In situ X-ray diffraction suggests a single phase transition caused by dehydration, in disagreement with spectroscopic and thermodynamic measurements. Neutron scattering, being sensitive toward the H 2 O and Li sublattices, reveals multiple phase transitions. We show that the loss of the final trace H 2 O leads to strain and grain boundary formation. Thus, controlled dehydration may be a viable strategy for high-throughput processing for roll-to-roll manufacturing of REAH solid electrolytes.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Interlayer Design for Halide Electrolytes in All‐Solid‐State Lithium Metal Batteries

Abstract All‐solid‐state lithium‐metal batteries (ASSLMBs) are promising for transportation electrification due to their superior safety and high energy density. Lithium halide electrolytes provide excellent processing flexibility, high ionic conductivity, and anodic stability (>4.1 V), making them highly compatible with high‐voltage cathodes, surpassing sulfide electrolytes (<2.1 V). Nevertheless, halide electrolytes suffer from low cathodic stability and form an electronically conductive interphase with lithium, resulting in a critical current density (CCD) of nearly zero. Herein, Li 3 YbCl 6 electrolytes are synthesized that are kinetically stable with lithium by forming an electronic insulating solid electrolyte interphase. Guided by critical overpotential criteria, a PI 3 interlayer is designed that transforms into Li 6 PI 3 upon contact with lithium, substantially reducing the interfacial resistance of Li 3 YbCl 6 against lithium to 34 Ω and achieving a high critical overpotential of 114 mV. By substituting Yb with Lu, Li 3 LuCl 6 electrolytes with Li 6 PI 3 interlayers reach a CCD of 1.0 mA cm −2 at a capacity of 1.0 mAh cm −2 , comparable to sulfide electrolytes but with higher oxidation stability. Additionally, Li 6 PI 3 enables stable cycling of Li//Li cells with Li 3 LuCl 6 electrolytes at 0.5 mA cm −2 for 400 cycles and maintains 86.5% capacity in Li//LiCoO 2 cells after 220 cycles at 30 °C, paving the way for high‐performance ASSLMBs.

Chemistry↗
DOE OSTI2022

Stability Enhancement and Microstructural Modification of Ni-Rich Cathodes via Halide Doping

In this study, elemental doping is an effective strategy to modify surface and bulk chemistry in NMC cathode materials. By adding small amounts of lithium halide salts during the calcination process, the Ni-rich NMC811 cathode is doped with Br, Cl, or F halogens. The dopant type has a significant impact on the lithiation process and heavily influences the final cathode porosity and surface morphology. Utilizing a variety of electrochemical, surface, and bulk characterization techniques, it is demonstrated that an initial content of 5 mol % LiBr or LiCl in the lithium source is effective in improving capacity retention while also providing excellent rate performance. The improvements are attributed to a substantial increase in specific surface area, the formation of a stable cathode electrolyte interface (CEI) layer, and suppressed surface reconstruction. In addition, the particle microstructure is better equipped to handle cyclic volume changes with increased values of critical crack lengths. Overall, it is demonstrated that anion doping via the addition of lithium halide salts is a facile approach toward Ni-rich NMC modification for enhanced cathode performance.

25 ENERGY STORAGE↗
DOE OSTI2022

Structural design strategies for superionic sodium halide solid electrolytes

We report sodium all-solid-state batteries (ASSBs) with superionic solid electrolytes (SEs) show substantial potential for large-scale energy-storage applications. Recently, lithium halide SEs have attracted attention owing to their potential compatibility with high-voltage cathode materials and high ionic conductivity. Although sodium halide SEs are believed to exhibit good electrochemical stability, very few compounds have been reported. This study provides design principles for superionic sodium halide SEs through systematic theoretical investigations of Na 3 MX 6 (X = Cl, Br, and I). The Na 3 MX 6 structures depend on the types and sizes of M and X: Na 3 MCl 6 and Na 3 MBr 6 prefer the $P\bar{3}$1c, P2 1 /n and $R\bar{3}$ phases, whereas Na 3 MI 6 prefers the C2/m phase. The Na 3 MI 6 C2/m phase is found to exhibit reasonably high ionic conductivity (~10 -4 S/cm -1 ) and anion mixing with Br further improve Na-ion migration, leading to an even higher ionic conductivity (~10 -3 S/cm -1 ) for Na 3 MBr 3 I 3 . The material design principles in this study provide fundamental guidelines for the development of superionic Na halide SEs for high-voltage Na ASSBs

25 ENERGY STORAGE↗
DOE OSTI2023

Halide Substitution Effects on Lithium-Ion Diffusion in Protonated Antiperovskites

Solid-state electrolytes (SSEs) for all-solid-state lithium-ion batteries are generating intense interest because these batteries can improve the safety and performance compared with devices fabricated with conventional, flammable liquid electrolytes. In these SSEs, it has been suggested that Li + ion diffusion in the grain boundaries is hindered and is a critical determinant of the overall ionic conductivity (σ). However, Li + ion diffusivities in the grain (D G ) and the grain boundary (D GB ) are difficult to determine experimentally, with few techniques capable of distinguishing the individual contributions. Here, we distinguished the D G and D GB for the protonated lithium antiperovskites (pLiAPs) SSEs: Li 2 OHCl, Li 2 OHBr, Li 2 OHF 0.1 Cl 0.9 , Li 2 OHF 0.1 Br 0.9 , and Li 2 OHCl 0.3 7Br 0.63 . The measurements were obtained directly from 7 Li pulsed-field gradient nuclear magnetic resonance (PFG-NMR) at 353 K. The 7 Li PFG-NMR echo profiles were composed of two primary components with additional secondary oscillatory components – the so-called NMR diffraction phenomenon. The length scale separating the two main components corresponds to a diffusion length of ~1.7 µm, which is thought to be the average grain size (by diameter). The short-range (≤ 1.7 µm) diffusion component associated with D G (≈10 -11 m 2 /s) varied minimally with halide substitution, while the long-range (≥ 1.7 µm) component D GB (≈10 -12 to 10 -15 m 2 /s) was highly sensitive to the substitution of halides and closely correlated with s. In addition, from the comparison of the ratio D GB /D G to D t (the Li + ion diffusion coefficient estimated from the rotational correlation time, t c ), it was determined that the contribution of D G to σ is negligible; 0.01 ~ 0.04 in the pLiAPs studied here. Finally, these insights provide fundamental understanding of the halide substitution effects on Li + ion grain versus grain boundary diffusion, and suggest that careful engineering of the grain boundaries at the microscopic level is necessary to achieve high-performance pLiAP SSEs.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2024

Anionic Effects on Concentrated Aqueous Lithium Ion Dynamics

In this article, the structural dynamics, chemical reactivity, anisotropy, diffusivity, viscosity, and density were measured for concentrated lithium salt solutions, including lithium chloride (LiCl), lithium bromide (LiBr), lithium nitrite (LiNO 2 ), and lithium nitrate (LiNO 3 ), with methyl thiocyanate as an infrared vibrational probe molecule, using two-dimensional infrared spectroscopy (2D IR), nuclear magnetic resonance (NMR) spectroscopy, and viscometry. 2D IR, NMR, and viscosity results show that LiNO 2 exhibits longer correlation times, lower diffusivity, and nearly four times greater viscosity when compared to the other lithium salt solutions of the same concentration, suggesting that nitrite anions may strongly facilitate structure formation via strengthening water-ion interactions, directly impacting bulk solution properties at sufficiently high concentrations. Additionally, the LiNO 2 and LiNO 3 solutions show significantly reduced chemical reactivity with respect to lithium cations coordinating with the methyl thiocyanate when compared to the lithium halide salts.

2D IR↗
DOE OSTI2022

Self-assembling and self-healing rechargeable Li batteries Final Scientific/Technical Report

PROJECT OBJECTIVE: Investigate formation of lithium halide containing solid electrolyte interface. Characterize the structure and composition of the solid electrolyte interface surface film and morphology of the electrochemically deposited Li. Develop combinations of electrolytes (solvents + salts) and electrolyte additives that produce a highly Li-ion conducting, mechanically robust, and self-healing solid electrolyte interface to suppress Li dendrite formation and improve Coulombic efficiency.

Chiang, Yet-Ming↗
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 OSTI2021

Material Design Strategy for Halide Solid Electrolytes Li 3 MX 6 (X = Cl, Br, and I) for All-Solid-State High-Voltage Li-Ion Batteries

Although several solid electrolyte (SE) candidates have been explored, achieving the necessary combination of performance, stability, and processability has been challenging. Recently, several lithium ternary halides have attracted increasing attention for SEs because of their favorable combination of high ionic conductivity and wide electrochemical window. This study aims to provide a material design strategy for lithium halides Li 3 MX 6 (X = Cl, Br, and I) for high-voltage all-solid-state Li-ion batteries, achieved by the systematic investigation of crystal structures, phase and electrochemical stabilities, electronic and mechanical properties, and ionic conductivities. Calculation results reveal that the electronegativity difference between M and X affects structural properties and stabilities. Weak Coulomb interactions in Li 3 MX 6 result in the preference of the monoclinic phase, and the oxidation potential and chemical stability against the cathode materials of Li 3 MX 6 increase for relatively small X. Chlorides exhibit the highest oxidation potential (~4.3 V) among Li 3 MX 6 , suggesting that chlorides are appropriate SEs for high-voltage cathodes. The band gap and elastic moduli increase for relatively small X, suggesting the relatively low electronic conductivity and elastic deformability of chlorides. Chlorides with transition metals typically exhibit trigonal phases, a wider electrochemical stability window, a larger band gap, and higher elastic moduli compared to other types of halides. Additionally, chloride Li 3 MCl 6 is expected to have relatively high ionic conductivities with the aliovalent substitution of M 3+ to Zr 4+ and the anion mixing of Cl with Br. The findings of this study will provide fundamental guidelines for the development of lithium halide SEs for high-voltage all-solid-state Li-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2021

A universal wet-chemistry synthesis of solid-state halide electrolytes for all-solid-state lithium-metal batteries

Solid-state halide electrolytes have gained revived research interests owing to their high ionic conductivity and high-voltage stability. However, synthesizing halide electrolytes from a liquid phase is extremely challenging because of the vulnerability of metal halides to hydrolysis. In this work, ammonium-assisted wet chemistry is reported to synthesize various solid-state halide electrolytes with an exceptional ionic conductivity (>1 microsiemens per centimeter). Microstrain-induced localized microstructure change is found to be beneficial to lithium ion transport in halide electrolytes. Furthermore, the interfacial incompatibility between halide electrolytes and lithium metal is alleviated by transforming the mixed electronic/ionic conductive interface into a lithium ion–conductive interface. Such all-solid-state lithium-metal batteries (ASSLMBs) demonstrate a high initial coulombic efficiency of 98.1% based on lithium cobalt oxide and a high discharge capacity of 166.9 microampere hours per gram based on single-crystal LiNi 0.6 Mn 0.2 Co 0.2 O 2 . This work provides universal approaches in both material synthesis and interface design for developing halide-based ASSLMBs.

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

Tetrahedral Tilting and Lithium‐Ion Transport in Halide Argyrodites Prepared by Rapid, Microwave‐Assisted Synthesis

Abstract This study demonstrates a rapid, dry, microwave‐assisted (MW) synthesis method that enables preparation of halide argyrodites ( , , ) in less than 20 min. The structures and ion transport properties of the resulting materials are compared with those synthesized by conventional solid‐state synthesis methods. The microwave‐assisted method leads to increased site disorder and elevated Arrhenius prefactors (), which lead to an order of magnitude improvement in the 30 ionic conductivity of MW‐. X‐ray pair distribution function analysis (XPDF) reveals significant rotational disorder of the units, which is impacted by the synthesis method, choice of halide, and presence of / site disorder. These rotational displacements are strongly correlated with ion transport, specifically and entropy of migration (). Overall, this study demonstrates a rapid synthesis route for preparing high‐quality halide argyrodite solid‐state electrolytes in less than 20 min, and further unravels atomistic insights into the interplay of structural disorder, rotational dynamics, and ion transport mechanisms.

36 MATERIALS SCIENCE↗