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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2022

Anharmonic Cation–Anion Coupling Dynamics Assisted Lithium‐Ion Diffusion in Sulfide Solid Electrolytes

Abstract Sulfide‐based lithium superionic conductors often show higher Li‐ion conductivity than other types of electrolyte materials. This work unveils a unique Li‐ion conductive behavior in these materials through the perspective of anharmonic coupling assisted Li‐ion diffusion. Li hopping events can happen simultaneously with various types of lattice dynamics, while only a statistically important synchronization of motions may indicate coupling. This method enables a direct evaluation of the coupling strength between these motions, which more fundamentally decides if a specific type of lattice motion is really anharmonically coupled to the Li hopping event and whether the coupling can facilitate the Li diffusion. By a new ab initio computational approach, this work unveils a unique phenomenon in prototype sulfide electrolytes in comparison with typical halide ones, that Li‐ion conduction can be boosted by the anharmonic coupling of low‐frequency Li phonon modes with high‐frequency anion stretching or flexing phonon modes, rather than the low‐frequency rotational modes. The coupling pushes Li ions toward the diffusion channels for reduced diffusion barriers. The result from the lower temperature range (≈0–300 K) of simulation can also be more relevant to the application of solid‐state batteries.

Chemistry↗
DOE OSTI2020

Perspectives for Polymer Electrolytes: A View from Fundamentals of Ionic Conductivity

We present a brief overview of current developments in the field of polymer electrolytes, with the focus on single-ion conducting polymers. The latter have significant advantages relative to electrolytes with dual-ion conductivity for use in energy storage devices. First we discuss various mechanisms of ionic conductivity in polymers and fundamental limitations imposed by these mechanisms. We also emphasize the role of ion–ion correlations in conductivity that are not negligible in concentrated and semidilute ionic systems. Next we discuss several classes of polymer electrolytes (gels, block copolymers, and composites) that are already employed or have good potential to be employed in current battery technologies. At the end we discuss perspectives for the design of dry single-ion conducting polymer electrolytes with required room temperature conductivity.

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

Unraveling Ion Transport in Trifluoromethanesulfonimide Pentablock Copolymer Membranes in Nonaqueous Electrolytes

Cation exchange membranes provide a key function in various nonaqueous energy storage technologies. As such, understanding the role of a nonaqueous liquid electrolyte on ion transport through a membrane is imperative. This study unravels relationships between membrane ion transport and electrolyte salt concentration utilizing a trifluoromethanesulfonimide-based pentablock copolymer membrane with polar and nonpolar nonaqueous electrolyte solutions. Here, the membrane plasticized with propylene carbonate (PC) exhibits a single-ion conductivity of 9.3 × 10 –6 S/cm at 25 °C. Tailoring the nonaqueous electrolyte and electrolyte salt concentration enables the single-ion conducting membrane to maintain a high cation transport number, >0.75, and boost ion conductivity more than 10 times to 1.3 × 10 –4 S/cm at 25 °C for the PC-based electrolyte solution. The findings provide critically important design parameters for energy storage systems utilizing nonaqueous electrolytes, such as Li- and Na-ion batteries and nonaqueous flow battery technologies.

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

Machine learning informed rational design of high entropy double perovskite oxide universal air/steam electrodes for solid oxide electrochemical cells

Due to their high efficiency and versatility, solid oxide electrochemical cells (SOCs) are poised to play a significant role in future energy conversion and storage applications. In recent years, SOCs have bifurcated into two distinct categories: traditional oxygen-ion conducting SOCs that typically operate from ∼650—850 °C and the more recent proton-conducting ceramic (PCC) SOCs that typically operate from ∼400—650 °C. Current performance and lifetime of both oxygen-ion conducting SOCs and PCCs is primarily limited by the air/steam electrode, which facilitates the oxygen reduction reaction (ORR) during fuel cell operation and must also facilitate the oxygen evolution reaction (OER) during electrolysis operation. Here, we present a newly designed high-entropy double perovskite oxide suitable as a universal ORR/OER electrode for both oxygen-ion conducting SOCs and PCCs. Machine learning methods are applied to identify chemical descriptors for highly catalytic high-entropy double perovskite oxides (AA’B 2 O 6 ) across a large compositional space. Based on the machine-learning guidance, we ultimately converge on Ba 0.9 Cs 0.1 (Ca 0.2 Gd 0.2 La 0.2 Pr 0.2 Sr 0.2 )Co 1.5 Fe 0.5 O 6 (CsBaHEO) as a universal air/steam electrode. Structure stabilization is accomplished by an equimolar five-cation high-entropy composition on the A’-site, while cesium substitution on the A-site enhances the electrical conductivity and leads to a higher oxygen vacancy concentration. This material exhibits versatility and high performance in reversible oxygen-ion SOCs, reversible PCCs, and also large-scale tubular PCCs. For example, the CsBaHEO-based PCC reaches 1018 mW∙cm −2 at 600°C, while a large-scale tubular PCC using CsBaHEO for electrolysis achieves a hydrogen production rate of 21.314 ML∙min −1 at 600 °C.

Cell↗
DOE OSTI2021

Ion transport in polymerized lyotropic liquid crystals containing ionic liquid

In this work, we investigate the effect of morphology and segmental dynamics on ion transport in polymerized lyotropic liquid crystals (polyLLCs) containing 1-butyl-3-methylimidazolium tetrafluoroborate as ionic liquid (IL). We demonstrate that two important factors, which affect ion conduction in polyLLCs, are grain size and chain density at the interface. The polyLLC with large grain size (70 nm) shows significant reduction in ion conductivity (one order of magnitude) compared to its homopolymer/IL mixture. However, the polyLLC with small grain size (20 nm) has little difference in ion conductivity compared to its homopolymer/IL mixture. It is observed that decreasing the chain density enhances the interaction of IL with polymer chains and consequently slows the relaxation of polymer chains. Finally, in addition, comparing the dynamics of polymer chains in mixtures of homopolymer/IL and templated LLC mesophases shows that the confinement in LLC structure prolongs the relaxation of polymer chains.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Fluorine-Free Ion-Selective Membrane with Enhanced Mg 2+ Transport for Mg-Organic Batteries

Magnesium batteries offer a safer alternative for next-generation battery technology due to their insusceptibility to dendrite deposition. Selective membranes tailored for magnesium-ion conduction will unlock further technological advancement. Herein, we demonstrate fluorine-free magnesiated sulfonated poly(ether ether ketone) (Mg-SPEEK) selective membranes capable of facilitating magnesium-ion conduction while effectively rejecting soluble organic species. These membranes demonstrate a reversible Mg plating and stripping Coulombic efficiency (CE) of 85.4% and an ionic conductivity of 3.3 × 10 –4 S cm –1 at room temperature, surpassing those for a Mg-Nafion selective membrane. Theoretical density functional theory (DFT) calculations reveal that SPEEK possesses more localized charge centers along its backbone compared with Nafion, potentially facilitating enhanced ion conduction. Finally, full cells assembled with Mg-SPEEK coupled with the organic cathode pyrene-4,5,9,10-tetraone (PTO) and Mg metal demonstrated significantly improved capacity retention as compared to those assembled with conventional nonselective separators.

25 ENERGY STORAGE↗
DOE OSTI2025

Li 3.6 In 7 S 11.8 Cl: an air- and moisture-stable superionic conductor

Li 3.6 In 7 S 11.8 Cl has a face-centered cubic arrangement of S 2− /Cl − stabilized by Li + /In 3+ that form 3D ion conduction paths. The moisture stability and fast ion conduction make Li 3.6 In 7 S 11.8 Cl a promising electrolyte for solid-state batteries.

Oyekunle, Ifeoluwa P. [Department of Chemistry and↗
DOE OSTI2022

Lithium-Ion Mobility in Layered Oxide Li 2 (La 0.75 Li 0.25 )(Ta 1.5 Ti 0.5 )O 7 Containing Lithium on both Intra and Inter‐Stack Positions

With the aid of neutron diffraction and electrochemical impedance spectroscopy, we have demonstrated the effect of the increase in lithium concentration and distribution on Li-ion conductivity. This has been done through the synthesis of a layered oxide Li 2 (La 0.75 Li 0.25 )(Ta 1.5 Ti 0.5 )O 7 , with the so-called Ruddlesden-Popper type structure, where bilayer stacks of (Ta/Ti)O 6 octahedra are separated by lithium ions, located in inter-stack spaces. There are also intra-stack spaces that are occupied by a mixture of La and Li, as confirmed by neutron diffraction. The distribution of lithium over both inter- and intra-stack positions leads to the enhancement of Li-ion conductivity in Li 2 (La 0.75 Li 0.25 )(Ta 1.5 Ti 0.5 )O 7 compared to Li 2 La(TaTi)O 7 , which has a lower concentration of lithium ions, located only in inter-stack spaces. Furthermore, the analyses of real and imaginary components of electrochemical impedance data confirm the enhanced mobility of ions in Li 2 (La 0.75 Li 0.25 )(Ta 1.5 Ti 0.5 )O 7 . While the Li-ion conductivity needs further improvement for practical applications, the success of the strategy implemented in this work offers a useful methodology for the design of layered ionic conductors.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2020

Potassium Prussian blue-coated Li-rich cathode with enhanced lithium ion storage property

With high specific capacity, the layered Li-rich Mn-based oxide (LRMO) is a promising candidate cathode material for Li-ion batteries. However, the irreversible release of Li-ions during the first charging process, instability of LRMO/electrolyte interface and relatively low ion conductivity of LRMO result in low initial Coulombic efficiency (ICE), poor cycle stability and rate performance, which prohibit its further application. Furthermore, interface engineering via additive coating is expected to effectively address these issues. Herein, we rely on potassium Prussian blue (KPB), a Li + acceptor with good ion conductivity, as a new coating material on LRMO particles. The KPB coating not only forms a protective layer on the surface of LRMO against electrolyte corrosion, but also functions as a host for Li + transport and accommodation, leading to enhanced ion conductivity and ICE of LRMO cathode. Consequently, 2 wt% KPB coated LRMO cathode achieved an initial discharge capacity of up to 281.7 mA h g -1 with an ICE of 85.69% compared to an ICE of 79.52% for the LRMO cathode without coating. The cycling and rate performance are also greatly improved as evidenced by the well maintained capacity of up to 176.8 mA h g -1 after 100 cycles at a current density of 0.5 C, compared to the limited capacity of only 135.3 mA h g -1 for the LRMO cathode without coating. Overall, this work pioneers the use of potassium Prussian blue as additive coating material to enhance performance of LRMO cathode, and we expect it to inspire the battery community with new strategies of material engineering/design toward practical application in high-energy lithium-ion batteries.

25 ENERGY STORAGE↗
DOE OSTI2020

Proton-conducting oxides for energy conversion and storage

Proton-conducting oxides are a class of solid-state ion-conducting ceramic materials that demonstrate significant hydrogen ion (proton) conductivity at intermediate temperatures (e.g., 300–700 °C). They are garnering significant attention due to several unique characteristics that distinguish them from both higher temperature oxygen ion conducting oxides and lower temperature proton-conducting polymers. By enabling proton-mediated electrochemistry under both dry and wet environments at moderate temperatures, protonic ceramics provide unique opportunities to enhance or synergize a diverse range of complementary electrochemical and thermochemical processes. Because of this potential, significant efforts have been devoted to advancing numerous energy-related applications using these materials. This review aims to comprehensively summarize these applications and analyze the most up-to-date and future developments of proton-conducting oxides. We aim to bring together this diverse subject matter by integrating the fundamentals of proton-conducting oxides with application-oriented insights. We begin with a historical roadmap, followed by a basic overview of the materials, theories and fundamentals, and fabrication and processing technologies underlying the field. The central section of our review summarizes major applications and developments of proton-conducting ceramics, ranging from maturing applications approaching commercialization to embryonic technologies just now emerging from the lab. These include protonic ceramic fuel cells, protonic ceramic electrolysis cells, reversible protonic ceramic electrochemical cells, protonic ceramic membrane reactors, and protonic ceramic electrochemical reactors. For each application, we analyze both the prospects and challenges and offer recommendations for future research directions so that tomorrow's researchers can continue to advance the development and commercialization of these fascinating materials.

Duan, Chuancheng (ORCID:0000000218261415)↗
DOE OSTI2022

Developing reactors for electrifying bio-methanation: a perspective from bio-electrochemistry

The integration of microbial synthesis with renewable electricity is an emerging route for both CO 2 utilization and seasonal energy storage in the form of stored bio-electrofuels. The major benefits of electrifying bioreactors include: using highly selective bio-catalysts for CO 2 conversion under mild reaction conditions; decoupling the production of more facile electrochemical intermediates, such as hydrogen, at the electrode from the production of bio-catalyzed multi-electron and/or carbon products, such as methane or acetate; using microbes as robust and self-regenerating catalysts enabling higher efficiency and durability in CO 2 conversion systems compared to inorganic catalysis. In this Perspective, we propose research aimed at developing electro-bioreactor components that will increase the productivity of the reactor while maintaining high energy efficiency and biocompatible reaction conditions to fully realize the benefits of electrified bioreactors. Furthermore, these developments include: flow reactors with tailored 3D electrodes to optimally use the reactor volume, electrocatalysts designed for peak performance in neutral pH electrolytes, high conductivity microbial media, and new membrane separator materials with high ion conductivity and low gas permeability. Production of methane via a hybrid electrical-biological approach is taken as a case study to motivate these developments. Finally, an iterative design–manufacture–test cycle, enabled by additive manufacturing and 3D printing technologies, is proposed to rapidly prototype components prior to large-scale manufacturing.

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

Percolating Interfacial Layers Enhance Conductivity in Polymer–Composite Electrolytes

Here, this study investigates the impact of the ceramic particle size on the bulk and interfacial ion transport properties of composite polymer electrolytes. The ceramic particles used for this study are micrometer-sized commercial lithium lanthanum titanate (LLTO) powders and LLTO nanorods (NR) prepared in the laboratory. The polymer matrices are vinylene carbonate (VEC) based single-ion-conducting (SIC) and dual-ion-conducting (DIC) polymer electrolytes. Our results reveal that the addition of LLTO NR results in improved ion transport, while the addition of commercial LLTO is ineffective or even detrimental. We ascribe these results to the formation of an interfacial polymer layer around the LLTO particles with enhanced Li + mobility and estimate the thickness of the interfacial layer to be ∼5 nm. The high surface-to-volume ratio of the LLTO NR leads to the percolation of the interfacial region at a relatively low ceramic loading of 30 wt %. This study highlights the importance of achieving percolation of the interface region (as opposed to the particles themselves) within the composite electrolyte when the interfacial layer is the enhancement mechanism.

Ock, Ji-young↗
DOE OSTI2022

Effect of Tethering Anions in Block Copolymer Electrolytes via Molecular Dynamics Simulations

Ion-containing block copolymers (BCPs) are promising solid-state electrolytes as they can combine ion conduction and mechanical robustness via multiple microphases. However, salt-doped BCPs can have low ion conduction and transference number. One strategy to increase transference number is to tether anions to the polymer backbone (creating a single-ion conductor), though this may impact cation mobility. Leveraging coarse-grained molecular dynamics simulations, we compare the effects of ion concentration and polymer dielectric constant on BCPs with and without bonding anions to the chain (without changing any other chemical properties). We find that single-ion BCPs have higher cation conductivity than analogous salt-doped BCPs, especially at moderate ion concentrations. Furthermore, we also compare several structural features of these systems; notably, tethering anions causes the ions to spread more evenly throughout the conducting phase, which is related to improved cation conduction.

25 ENERGY STORAGE↗
DOE OSTI2026

Tuning Anion Composition and Mobility to Balance Ionic Conductivity and Cation Selectivity in Solid Polymer Electrolytes

Solid polymer electrolytes (SPEs) offer a promising route toward safe and high-performance electrochemical energy storage, yet a fundamental challenge in SPEs involves improving ionic conductivity while maintaining selective cation transport. The hurdle exists because ion transport is typically coupled closely to polymer segmental dynamics. Herein, a glassy single-ion-conducting polymer, poly[lithium sulfonyl(trifluoromethane sulfonyl)imide methacrylate] (PLiMTFSI), in which the anions were tethered to the polymer, was blended with a flexible polymer, poly(oligo-oxyethylene methyl ether methacrylate) (POEM), and a series of small-molecule lithium salts, in which the anions were untethered [lithium bis(trifluoromethane­sulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), lithium trifluoromethanesulfonate (LiTf), or lithium perchlorate (LiClO 4 )]. The impact of salt anion volume and tethered-to-untethered anion ratio on the ion conduction behavior and thermal properties of blend electrolytes was investigated. In some cases, conductivity could be enhanced through this ternary blend approach. For example, a POEM-based polymer blend containing a bulky salt anion (TFSI⁻) and an equimolar mixture of PLiMTFSI and LiTFSI exhibited a Li + conductivity (4.8×10 -4 S/cm) an order of magnitude higher than that of a comparable POEM / LiTFSI system (6.3×10 -5 S/cm) at 100 °C. This enhancement was attributed to a more than ninefold increase in lithium transference number (0.66 in the ternary blend vs. 0.07 in POEM / LiTFSI). Overall, this study highlights the potential for tuning anion composition and mobility to achieve relatively high ionic conductivities and maintain selective cation transport in SPEs, offering a pathway to enable batteries that tolerate elevated temperatures.

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

Transferring Liquid Metal to form a Hybrid Solid Electrolyte via a Wettability-Tuning Technology for Lithium-Metal Anodes

Integrating solid-state electrolyte (SSE) into Li-metal anodes has demonstrated great promise to unleash the high energy density of rechargeable Li-metal batteries. However, fabricating a highly cyclable SSE/Li-metal anode remains a major challenge because the densification of the SSE is usually incompatible with the reactive Li metal. Here, a liquid-metal-derived hybrid solid electrolyte (HSE) is proposed, and a facile transfer technology to construct an artificial HSE on the Li metal is reported. By tuning the wettability of the transfer substrates, electron- and ion-conductive liquid metal is sandwiched between electron-insulating and ion-conductive LiF and oxides to form the HSE. The transfer technology renders the HSE continuous, dense, and uniform. The HSE, having high ion transport, electron shut-off, and mechanical strength, makes the composite anode deliver excellent cyclability for over 4000 h at 0.5 mA cm(-2) and 1 mAh cm(-2) in a symmetrical cell. When pairing with LiFePO4 and sulfur cathodes, the HSE-coated Li metal dramatically enhances the performance of full cells. Therefore, this work demonstrates that tuning the interfacial wetting properties provides an alternate approach to build a robust solid electrolyte, which enables highly efficient Li-metal anodes.

li-metal anodes↗
DOE OSTI2020

Tuning the Anode–Electrolyte Interface Chemistry for Garnet-Based Solid-State Li Metal Batteries

Lithium (Li) metal anode is a promising candidate for high energy density solid-state batteries. However, the interface issues, including large interfacial resistance and Li dendrite generation, have always frustrated the attempt to commercialize solid-state Li metal batteries (SSLBs). Here, we report that infusing the garnet-type solid electrolytes (GSEs) with air-stable electrolyte Li 3 PO 4 (LPO) dramatically reduces the interfacial resistance to ~1 Ω cm 2 and achieves a high critical current density of 2.2 mA cm -2 under ambient condition due to enhanced interfacial stability to Li metal anode. The coated and infused LPO electrolytes not only improve the mechanical strength and Li-ion conductivity of grain boundaries, but also form a stable Li-ion conductive but electron-insulating LPO-derived solid-electrolyte interphase between Li metal and GSEs, and consequently eliminates the Li dendrites growth and prevents the direct reduction of GSEs by Li metal over a long cycle life. This interface engineering approach together with grain-boundary modification on GSEs represents a promising strategy to revolutionize the anode-electrolyte interface chemistry for SSLBs and provides new design strategy for other-types of solid-state batteries.

25 ENERGY STORAGE↗
DOE OSTI2021

Multifunctional Separator Allows Stable Cycling of Potassium Metal Anodes and of Potassium Metal Batteries

Here, this is the first report of a multifunctional separator for potassium-metal batteries (KMBs). Here, double-coated tape-cast microscale AlF 3 on polypropylene (AlF 3 @PP) yields state-of-the-art electrochemical performance: symmetric cells are stable after 1000 cycles (2000 h) at 0.5 mA cm –2 and 0.5 mAh cm –2 , with 0.042 V overpotential. Stability is maintained at 5.0 mA cm –2 for 600 cycles (240 h), with 0.138 V overpotential. Postcycled plated surface is dendrite-free, while stripped surface contains smooth solid electrolyte interphase (SEI). Conventional PP cells fail rapidly, with dendrites at plating, and “dead metal” and SEI clumps at stripping. Potassium hexacyanoferrate(III) cathode KMBs with AlF 3 @PP display enhanced capacity retention (91% at 100 cycles vs 58%). AlF 3 partially reacts with K to form an artificial SEI containing KF, AlF 3 , and Al 2 O 3 phases. The AlF 3 @PP promotes complete electrolyte wetting and enhances uptake, improves ion conductivity, and increases ion transference number. The higher of K + transference number is ascribed to the strong interaction between AlF 3 and FSI – anions, as revealed through 19 F NMR. The enhancement in wetting and performance is general, being demonstrated with ester- and ether-based solvents, with K-, Na-, or Li- salts, and with different commercial separators. In full batteries, AlF 3 prevents Fe crossover and cycling-induced cathode pulverization.

NMB↗
DOE OSTI2025

AI‐Accelerated Optimization of Self‐Assembled Organic Mixed Ionic‐Electronic Conductors (OMIEC) (Final Report)

This document describes research activities, products and outcomes of a DOE-funded program to help accelerate development of Organic Mixed Ionic Electronic Conductors (OMIECs) using neutron scattering and high-throughput experimentation. OMIECs are organic materials that conduct both ionic and electronic charge carriers. For these new OMIEC materials, self-assembling ion-conducting block copolymers (BCPs) are used as a structural template for electronic conducting polymers. This forms OMIECs with long-range structural order that can help facilitate long-range electronic transport. The conductive properties of OMIECs are closely associated with their structure, which is affected by solution conditions and polymer macromolecular designs. Thus high-throughput experimentation has been implemented to explore this large design space effectively. The BCP-CP OMIEC systems explored are composed of ion-conducting diblock or triblock copolymers containing polyethylene oxide (PEO), di(ethylene glycol) ethyl ether acrylate (DEGEEA) or poly(ethylene glycol) methyl ether acrylate) (PEGMEA) hydrophilic blocks. These blocks will be coupled with either polypropylene oxide (PPO) or polyheptafluorobutyl acrylate (PHFBA) hydrophobic blocks to drive assembly. The electronic conducting component consists of several different types of conjugated polymers. Small angle scattering of neutrons and X-rays (SANS/SAXS) as well as electrochemical analysis have been coupled with modern algorithms for autonomous research using artificial intelligence (AI).

36 MATERIALS SCIENCE↗