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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 559 records · Page 31
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

NaSICON-type materials for lithium-ion battery applications: Progress and challenges

Lithium-ion batteries (LIBs) are widely used in electric vehicles, energy storage, smart grids, and portable devices due to their high average output voltage and energy density. NaSICON-type materials have been identified as potential candidates for electrode and solid electrolyte materials for LIBs due to their 3D framework, which contains Li + ions, excellent ionic conductivity, and thermal stability. NaSICON-type materials have a 3D framework and a fast Li + diffusion pathway, making them suitable for use in LIBs. However, their application as solid electrolytes is limited due to poorer ionic conductivity and interfacial stability compared to commercialized liquid electrolytes. Furthermore, their use as electrode materials is restricted by their low electronic conductivity. Here, this review provides an overview of NaSICON-type materials, including their common structure, Li + diffusion mechanism, and preparation strategies. The article also discusses the application and modification strategies of NaSICON-type materials for LIBs, classifying them as anode materials, cathode materials, and solid electrolyte materials. Additionally, the potential use of NaSICON-type materials as modification materials for cathode materials for LIBs is briefly mentioned. Building on previous work on NaSICON-type materials, we propose potential areas for further development and wider applications of these materials in LIBs.

25 ENERGY STORAGE↗
DOE OSTI2020

Consolidating Lithiothermic-Ready Transition Metals for Li2S-Based Cathodes

Li 2 S holds a promising role as a high-capacity Li-containing cathode, circumventing use of metallic lithium in constructing next-generation batteries to replace current Li-ion batteries. However, progress of Li 2 S cathode has been plagued by its intrinsic drawbacks, including high activation potentials, poor rate performance, and rapid capacity fading during long cycling. In this work, a series of Li 2 S/transition metal (TM) nanocomposites are synthesized via a lithiothermic reduction reaction, and it is realized that the presence of TMs in Li 2 S matrix can transform electrochemical behaviors of Li 2 S. On the one hand, the incorporation of W, Mo, or Ti greatly increases electronic and ionic conductivity of Li 2 S composites and inhibits the polysulfide dissolution via the TM—S bond, effectively addressing the drawbacks of Li 2 S cathodes. In particular, Li 2 S/W and Li 2 S/Mo exhibit the highest ionic conductivity of solid-phase Li-ion conductors ever-reported: 5.44 × 10 –2 and 3.62 × 10 –2 S m –1 , respectively. On the other hand, integrating Co, Mn, and Zn turns Li 2 S into a prelithiation agent, forming metal sulfides rather than S 8 after the full charge. These interesting findings may shed light on the design of Li 2 S-based cathode materials.

25 ENERGY STORAGE↗
DOE OSTI2018

Exploring interfacial stability of solid-state electrolytes at the lithium-metal anode surface

Solid state electrolytes are promising materials to mitigate the issues derived from the extreme reactivity of the lithium metal anodes in Li-metal batteries. The main properties sought for this application are high ionic conductivity, low electronic conductivity, and high interfacial stability. Here we investigate a class of sulfides (Li 10 GeP 2 S 12 , Li2P2S6, β-Li 3 PS 4 , and Li 7 P 3 S 11 ) that have shown relatively good ionic conductivities. However, little is known regarding their interfacial stability. We use density functional theory and ab initio molecular dynamics simulations to investigate the time evolution of the interfacial structure. We characterize atomic diffusion and reactions happening at the picosecond time scale, allowing us to identify the main interfacial products: Li 2 S, Li 3 P and Li 17 Ge 4 . We then study how the reactivity changes when the Li metal surface is coated with a thin film of Li 2 S.

25 ENERGY STORAGE↗
DOE OSTI2019

Highly Conductive Anion-Exchange Membranes Based on Cross-Linked Poly(norbornene): Vinyl Addition Polymerization

Cross-linked (XL) anion-exchange membranes (AEMs) synthesized by vinyl addition polymerization of norbornene were prepared for use in anion-exchange membrane electrochemical devices, including fuel cells and electrolyzers. Tetrablock copolymers composed of an all-hydrocarbon backbone with a very high ion-exchange capacity (IEC), 3.46 mequiv/g, were synthesized. Light cross-linking was found to be adequate for providing critical control over unwanted water uptake. This enabled use of very high IEC membranes. Without light cross-linking, the unwanted water uptake would cause swelling and softening of the membrane. The best performing membrane had no significant drop in ionic conductivity over 1000 h of aging in 1 M NaOH at 80 °C and a record high ionic conductivity of 198 mS/cm at 80 °C (for a chemically stable AEM). The number of bound and free water molecules per ion pair is described along with ion mobility comparisons to previous materials. Here, the membranes are suitable for electrochemical devices and were used in AEM fuel cells

08 HYDROGEN↗
DOE OSTI2016

Simulation of local ion transport in lamellar block copolymer electrolytes based on electron micrographs

A method is presented in this paper to relate local morphology and ionic conductivity in a solid, lamellar block copolymer electrolyte for lithium batteries, by simulating conductivity through transmission electron micrographs. The electrolyte consists of polystyrene-block-poly(ethylene oxide) mixed with lithium bis(trifluoromethanesulfonyl) imide salt (SEO/LiTFSI), where the polystyrene phase is structural phase and the poly(ethylene oxide)/LiTFSI phase is ionically conductive. The electric potential distribution is simulated in binarized micrographs by solving the Laplace equation with constant potential boundary conditions. A morphology factor, f, is reported for each image by calculating the effective conductivity relative to a homogenous conductor. Images from two samples are examined, one annealed with large lamellar grains and one unannealed with small grains. The average value off is 0.45 ± 0.04 for the annealed sample, and 0.37 ± 0.03 for the unannealed sample, both close to the value predicted by effective medium theory, 1/2. Simulated conductivities are compared to published experimental conductivities. The value of f Unannealed /f Annealed is 0.82 for simulations and 6.2 for experiments. Simulation results correspond well to predictions by effective medium theory but do not explain the experimental measurements. Finally, observation of nanoscale morphology over length scales greater than the size of the micrographs (~1 μm) may be required to explain the experimental results.

36 MATERIALS SCIENCE↗
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 OSTI2012

Solid electrolyte material manufacturable by polymer processing methods

The present invention relates generally to electrolyte materials. According to an embodiment, the present invention provides for a solid polymer electrolyte material that is ionically conductive, mechanically robust, and can be formed into desirable shapes using conventional polymer processing methods. An exemplary polymer electrolyte material has an elastic modulus in excess of 1.times.10.sup.6 Pa at 90 degrees C. and is characterized by an ionic conductivity of at least 1.times.10.sup.-5 Scm-1 at 90 degrees C. An exemplary material can be characterized by a two domain or three domain material system. An exemplary material can include material components made of diblock polymers or triblock polymers. Many uses are contemplated for the solid polymer electrolyte materials. For example, the present invention can be applied to improve Li-based batteries by means of enabling higher energy density, better thermal and environmental stability, lower rates of self-discharge, enhanced safety, lower manufacturing costs, and novel form factors.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Investigation of Conductivity and Ionic Transport of VO 2 (M) and VO 2 (R) via Electrochemical Study

Vanadium dioxides exist as a variety of polymorphs, each with differing structural and electrochemical capabilities. The monoclinic to rutile transition is an interesting system for study as the transition temperature is easily accessible at moderate temperature and corresponds to an increase in electrical conductivity by two orders of magnitude. The transition from monoclinic to rutile is characterized structurally herein using synchrotron-based x-ray diffraction and related to lithium ion electrochemistry using electrochemical impedance spectroscopy and intermittent pulsatile galvanostatic discharge tests. The experimental results indicate a decrease in ohmic resistance for lithium-based cells tested under higher temperatures. Complementary density functional theory calculations described the experimentally measured intercalation voltages and identified a possible Li-induced Li x VO 2 (M) to Li x VO 2 (R) phase transition during the discharging process rationalizing the favorable impact on the function of a lithium based electrochemical cell. Here, to our knowledge, this is the first observation of the metal—insulator transition of VO 2 in a full electrochemical cell.

25 ENERGY STORAGE↗
DOE OSTI2017

Mechanism of ion transport in perfluoropolyether electrolytes with a lithium salt

Perfluoropolyethers (PFPEs) are polymer electrolytes with fluorinated carbon backbones that have high flash points and have been shown to exhibit moderate conductivities and high cation transference numbers when mixed with lithium salts. Ion transport in four PFPE electrolytes with different endgroups was characterized by differential scanning calorimetry (DSC), ac impedance, and pulsed-field gradient NMR (PFG-NMR) as a function of salt concentration and temperature. In spite of the chemical similarity of the electrolytes, salt diffusion coefficients measured by PFG-NMR and the glass transition temperature measured by DSC appear to be uncorrelated to ionic conductivity measured by ac impedance. We calculate a non-dimensional parameter, β, that depends on the salt diffusion coefficients and ionic conductivity. We also use the Vogel–Tammann–Fulcher relationship to fit the temperature dependence of conductivity. We present a linear relationship between the prefactor in the VTF fit and β; both parameters vary by four orders of magnitude in our experimental window. Finally, our analysis suggests that transport in electrolytes with low dielectric constants (low β) is dictated by ion hopping between clusters.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2021

Formation of Stable Interphase of Polymer-in-Salt Electrolyte in All-Solid-State Lithium Batteries

The integration of solid-polymer electrolytes into all-solid-state lithium batteries is highly desirable to overcome the limitations of current battery configurations that have a low energy density and severe safety concerns. Polyacrylonitrile is an appealing matrix for solid-polymer electrolytes; however, the practical utilization of such polymer electrolytes in all-solid-state cells is impeded by inferior ionic conductivity and instability against a lithium-metal anode. In this work, we show that a polymer-in-salt electrolyte based on polyacrylonitrile with a lithium salt as the major component exhibits a wide electrochemically stable window, a high ionic conductivity, and an increased lithium-ion transference number. The growth of dendrites from the lithium-metal anode was suppressed effectively by the polymer-in-salt electrolyte to increase the safety features of the batteries. In addition, we found that a stable interphase was formed between the lithium-metal anode and the polymer-in-salt electrolyte to restrain the uncontrolled parasitic reactions, and we demonstrated an all-solid-state battery configuration with a LiFePO 4 cathode and the polymer-in-salt electrolyte, which exhibited a superior cycling stability and rate capability.

Gao, Hongcai↗
DOE OSTI2013

Lithium Polysulfidophosphates: A Family of Lithium-Conducting Sulfur-Rich Compounds for Lithium-Sulfur Batteries

Given the great potential for improving the energy density of state-of-the-art lithium-ion batteries by a factor of 5, a breakthrough in lithium-sulfur (Li-S) batteries will have a dramatic impact in a broad scope of energy related fields. Conventional Li-S batteries that use liquid electrolytes are intrinsically short-lived with low energy efficiency. The challenges stem from the poor electronic and ionic conductivities of elemental sulfur and its discharge products. We report herein lithium polysulfidophosphates (LPSP), a family of sulfur-rich compounds, as the enabler of long-lasting and energy-efficient Li-S batteries. LPSP have ionic conductivities of 3.0 10-5 S cm-1 at 25 oC, which is 8 orders of magnitude higher than that of Li2S (~10-13 S cm-1). The high Li-ion conductivity of LPSP is the salient characteristic of these compounds that impart the excellent cycling performance to Li-S batteries. In addition, the batteries are configured in an all-solid state that promises the safe cycling of high-energy batteries with metallic lithium anodes.

batteries↗
DOE OSTI2018

Electrochemical Performance of Nanosized Disordered LiVOPO 4

ε-LiVOPO4 is a promising multielectron cathode material for Li-ion batteries that can accommodate two electrons per vanadium, leading to higher energy densities. However, poor electronic conductivity and low lithium ion diffusivity currently result in low rate capability and poor cycle life. To enhance the electrochemical performance of ε-LiVOPO4, in this work, we optimized its solid-state synthesis route using in situ synchrotron X-ray diffraction and applied a combination of high-energy ball-milling with electronically and ionically conductive coatings aiming to improve bulk and surface Li diffusion. We show that high-energy ball-milling, while reducing the particle size also introduces structural disorder, as evidenced by 7Li and 31P NMR and X-ray absorption spectroscopy. We also show that a combination of electronically and ionically conductive coatings helps to utilize close to theoretical capacity for ε-LiVOPO4 at C/50 (1 C = 153 mA h g–1) and to enhance rate performance and capacity retention. The optimized ε-LiVOPO4/Li3VO4/acetylene black composite yields the high cycling capacity of 250 mA h g–1 at C/5 for over 70 cycles.

36 MATERIALS SCIENCE↗
DOE OSTI2024

Liquid-like solid-state diffusion of lithium ions in super-halide-rich argyrodite

The development of solid electrolytes with high ionic conductivity is essential for advancing safer, high-energy-density solid-state batteries, where lithium site distribution in the sublattice strongly affects ion transport. Here, we report a super-halide-rich argyrodite, Li 5.3 PS 4.3 Cl 1.7 , with remarkable room-temperature ionic conductivity (11.4 ± 0.7 mS cm -1 ) due to population of two additional interstitial lithium sites induced by vacancy redistribution. Prominent lithium density between lithium sites and elevated atomic displacement parameters indicate liquid-like diffusive behavior resembling sublattice melting. Combining electrochemical impedance spectroscopy, pulsed-field gradient NMR, and T 1 relaxation methods, we demonstrate that the augmented conductivity partly arises from a low energy barrier (0.08 eV) at the local scale, attributed to a three-site lithium distribution that drives correlated lithium dynamics. This work advances our understanding of the structure-dynamics interplay in super-halide-rich argyrodites, and highlighting their potential as solid-state battery electrolytes in cells with a coated single-crystal NMC82 cathode that achieve 170 mAh/g capacity at a 0.2 C rate .

25 ENERGY STORAGE↗
DOE OSTI2019

Evolution of Ion–Ion Interactions and Structures in Smectic Ionic Liquid Crystals

Mixture of ionic liquid, 1,3-dimethylimidazolium 2-methoxy(2-ethoxy(2-ethoxy(2-ethoxy)))ethylphosphite ([DMIm][MPEGP]), and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), which forms an ionic liquid crystal with a superior ionic conductivity, evolves a smectic structure through ion–ion interactions as a function of LiTFSI concentration. Here, nuclear magnetic resonance (NMR) spectroscopy and pulsed field gradient (PFG) NMR examinations showed that the morphology of the structures and the strength of ion–ion interactions are closely related to the ratio of Li + /[MPEGP] – . The results revealed structures composed of Li + : [MPEGP] – : TFSI – (≈ 3 : 4 : 1) mainly by the Coulombic interactions between Li + cations and phosphite head groups in [MPEGP] – anions. NMR diffraction on PFG-echo profiles revealed a cluster size of ~ 2 µm, inversely proportional to the number of mobile [MPEGP] – anions, and an ion diffusion on the cluster surfaces that is 1000 times faster than that in the bulk liquid. These observations suggest that the superior ionic conductivity in the mixture is mainly due to the fast ion transport on the cluster surfaces of smectic ionic liquid crystals. The variations of diffusion ratios between mobile Li + , TFSI – , [DMIm] + , and [MPEGP] – ions indicate that these mobile ions remaining in the voids of structures preserve the bulk ionic liquid properties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
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

Understanding the impact of SPMAK and PEGPEA in crosslinked PEGDA membranes: Methanol-carboxylate co-transport behavior and correlating structure-physicochemical-transport properties

Investigating multicomponent transport in dense, hydrated polymer membranes is necessary in applications such as fuel cells, electrolyzers, and desalination systems. Of particular interest are photoelectrochemical CO 2 reduction cells (PEC-CRC) which produce liquid products such as alcohols (methanol) and carboxylates (formate, acetate). Flux coupling and competitive sorption behavior of these products (solutes) have been found to affect permselectivity, thereby motivating us to investigate fundamental membrane structure-physicochemical-transport relationships. Past research has shown that systematic tuning of crosslinked cation exchange membranes (CEMs) with charge-neutral monoacrylate monomers containing alkyl and phenyl groups (i.e., poly(ethylene glycol) methacrylate (PEGMA), and poly(ethylene glycol) phenyl ether acrylate (PEGPEA)) can suppress acetate transport (permeability) in co-permeation with methanol. To further investigate this transport behavior and to enhance membrane ionic conductivities, 3-sulfopropyl methacrylate potassium (SPMAK), a sulfonated monoacrylate monomer is incorporated here. SPMAK content is varied with neutral PEGPEA and diacrylate crosslinker, poly (ethylene glycol) diacrylate (PEGDA) of two different chain lengths (n = 10 and 13) to prepare membranes of various compositions. Electrochemical and physicochemical properties including ionic conductivity, ion exchange capacity, and water uptake increase with increasing charged SPMAK content. Different states of water within hydrated membranes are probed using differential scanning calorimetry (DSC), where increasing intermediate (loosely bound) water is observed with increasing hydrophilic SPMAK content. The transport behavior of methanol and carboxylates (formate, acetate, propionate) are investigated, where permeabilities vary as methanol > formate > acetate ≈ propionate. Interestingly, permeabilities decrease with increasing PEGPEA content and are more dependent on solute diffusion than sorption. Permeabilities and diffusivities decrease while permselectivities increase with decreasing PEGDA chain length.

25 ENERGY STORAGE↗
DOE OSTI2022

A Review on Gel Polymer Electrolytes for Dye-Sensitized Solar Cells

Significant growth has been observed in the research domain of dye-sensitized solar cells (DSSCs) due to the simplicity in its manufacturing, low cost, and high-energy conversion efficiency. The electrolytes in DSSCs play an important role in determining the photovoltaic performance of the DSSCs, e.g., volatile liquid electrolytes suffer from poor thermal stability. Although low volatility liquid electrolytes and solid polymer electrolytes circumvent the stability issues, gel polymer electrolytes with high ionic conductivity and enduring stability are stimulating substitutes for liquid electrolytes in DSSC. Here, in this review paper, the advantages of gel polymer electrolytes (GPEs) are discussed along with other types of electrolytes, e.g., solid polymer electrolytes and p-type semiconductor-based electrolytes. The benefits of incorporating ionic liquids into GPEs are highlighted in conjunction with the factors that affect the ionic conductivity of GPEs. The strategies on the improvement of the properties of DSSCs based on GPE are also presented.

36 MATERIALS SCIENCE↗