Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “ionic conductivity”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

High performance of SDC and GDC core shell type composite electrolytes using methane as a fuel for low temperature SOFC

Nanocomposites Samarium doped Ceria (SDC), Gadolinium doped Ceria (GDC), core shell SDC amorphous Na{sub 2}CO{sub 3} (SDCC) and GDC amorphous Na{sub 2}CO{sub 3} (GDCC) were synthesized using co-precipitation method and then compared to obtain better solid oxide electrolytes materials for low temperature Solid Oxide Fuel Cell (SOFCs). The comparison is done in terms of structure, crystallanity, thermal stability, conductivity and cell performance. In present work, XRD analysis confirmed proper doping of Sm and Gd in both single phase (SDC, GDC) and dual phase core shell (SDCC, GDCC) electrolyte materials. EDX analysis validated the presence of Sm and Gd in both single and dual phase electrolyte materials; also confirming the presence of amorphous Na{sub 2}CO{sub 3} in SDCC and GDCC. From TGA analysis a steep weight loss is observed in case of SDCC and GDCC when temperature rises above 725 °C while SDC and GDC do not show any loss. The ionic conductivity and cell performance of single phase SDC and GDC nanocomposite were compared with core shell GDC/amorphous Na{sub 2}CO{sub 3} and SDC/ amorphous Na{sub 2}CO{sub 3} nanocomposites using methane fuel. It is observed that dual phase core shell electrolytes materials (SDCC, GDCC) show better performance in low temperature range than their corresponding single phase electrolyte materials (SDC, GDC) with methane fuel.

36 MATERIALS SCIENCE↗
DOE OSTI2012

Study of lithium borosilicotitanate glasses with LiCl

The effect of LiCl addition on the properties of Li{sub 2}O: B{sub 2}O{sub 3}: SiO{sub 2}: TiO{sub 2} glasses has been studied. It has been observed that the ionic conductivity increases by about half an order with LiCl addition. The decrease in glass transition temperature T{sub g} and increase in the molar volume with LiCl addition have good correlation with conductivity results. The observed increase in density of glasses has been explained on the basis of heavier Cl{sup -} ion which is accommodated in the interstices in the glass network.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Rare Earth and Transition Metal Containing Glasses

Transition metal (TM) and rare earth (RE) ions have been incorporated into many glass systems such as silicate, phosphate, and borosilicate-based oxide glasses, as well as in halide and chalcogenide glasses, that find applications ranging from optical, photonic, and magnetic devices, solid-state battery, to nuclear waste disposal. Understanding the structural role of RE and TM in these glasses can help to develop glass compositions for targeted applications with either high-optical emission efficiency, electrical conductivity, or chemical durability. In this chapter, we first provide a general introduction of the applications and structural features of RE and TM in glasses, then the critical aspects of molecular dynamics (MD) simulations of these glasses such as interatomic potentials, structural analysis tools to study RE and TM ions in glasses and their clustering behaviors, Quantitative Structure–Property Analysis (QSPR), diffusion and dynamic property calculations, and electronic structure calculations to understand electronic defects such as charge trapping and radiation effects are introduced. Three representative case studies are presented: the first one is on MD simulations of erbium- and europium-doped silica and silicate glasses, as well as cerium doped aluminophosphate glasses, that revealed the effect of glass composition on RE ion local structure and clustering behavior. Electronic structure calculations of cerium-doped glass show how the existence of multioxidation states help to mediate radiation-induced damages caused by excited electron–hole pairs was also discussed. The second one focuses on alkali vanadophosphate glasses where the existence of two vanadium oxidation states help to provide electronic conduction in the glasses while alkali ions provide ionic conduction. MD simulations were used to understand vanadium environments and other structural aspects in the phosphate glasses, as well as the ionic transport behaviors of alkali ions. The third case study is on zirconium-containing borosilicate and aluminosilicate glasses that find wide applications in nuclear waste disposal. MD simulations help to provide structural details of zirconium ions that are validated by diffraction and EXAFS spectra. The structural information was used to interpret changes of mechanical properties and chemical durability by using QSPR and other analyses-based MD-generated structure models.

Du, Jincheng↗
DOE OSTI2016

Improved electrical properties of free standing blend polymer for renewable energy resources

Blend polymer electrolytes are prepared for salt concentration (Ö/Li = 4) with the constant ratio (0.5 gm) of PEO and PAN using solution casting technique. The prepared free standing solid polymeric film is characterized by Field Emission Scanning Electron Microscopy (FESEM) which confirms the homogeneous distribution of dissociated salt in blend polymer matrix. After addition of salt the ionic conductivity value is found to be of the order of 7.13 × 10{sup −5} Scm{sup −1} which is three orders higher when compared with pure blend polymer films. The microscopic interaction among the polymer-ion, ion-ion has been confirmed by the Fourier Transform Infrared (FTIR) Spectroscopy. A very fine correlation has been built in the electrical conductivity and FTIR result. On the basis of above finding, a prepared free standing solid polymeric film appears to be appropriate for the energy storage/conversion device applications.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Influence of Magnetite Nanoparticles on the Dielectric Properties of Metal Oxide/Polymer Nanocomposites Based on Polypropylene

Structure and dielectric properties of polymer nanocomposites based on isotactic polypropylene and iron oxide (Fe{sub 3}O{sub 4}) nanoparticles are studied. Distribution of magnetite nanoparticles in a polymer matrix was studied by scanning electron microscopy (SEM, Carl Zeiss). Dielectric properties of nanocomposites were examined by means of E7-21 impedance spectrometer in the frequency range of 10{sup 2}–10{sup 6} Hz and temperature interval of 298–433 K. The frequency and temperature dependences of the dielectric permittivity ε, as well as the temperature dependence of log (ρ) were constructed. It is shown that introduction of the magnetite (Fe{sub 3}O{sub 4}) nanoparticles into a polypropylene matrix increases the dielectric permittivity of nanocomposites. An increase in the dielectric permittivity is explained by the increase in the polarization ability of nanocomposites. It is found that a decrease in the specific resistance with increasing temperature up to 318 K is associated with an increase in the ionic conductivity of nanocomposites. An increase in the resistance at temperatures higher than 358 K is due to the destruction of the crystalline phase of the polymer, as a result of which the distance between the Fe{sub 3}O{sub 4} nanoparticles increases.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Role of reduced precursor and solvolytic reagent molar ratio on preparation and properties of ionogel

In the present study, ionogels have been synthesized by immobilizing IL (1-ethyl-3-methylimidazolium tetrafluoroborate) in silica gel matrices using non-aqueous route. In this process, tetraethyl orho-silane (TEOS) as a precursor to silicon dioxide and formic acid as a solvolytic gelating reagent in reduced molar ratio 1:4 were used. We find that reduced molar concentration of formic acid results the formation of ionogels having less number of closed pores (totally isolated from their neighbours), larger density and stable monolithic form. TEM and SEM measurements are used to visualize the morphology of sample and closed pores present in the sample. N{sub 2}-sorption measurement is used to measure the pore parameters of the silica matrices which shows the mesoporous structure. DSC and TGA results show the change in phase transition temperature and thermal stability of IL upon confinement in silica matrices. Moreover, ionic conductivity of bulk and confined IL is measured using impedance spectroscopy and it has been found that it increases with increasing the temperature as well as concentration of IL in ionogels. Apart from these characterization techniques, ionogels have been characterized using FTIR and fluorescence spectroscopy which exhibit the change in vibrational frequencies and fluorescence behaviour of confined IL. - Highlights: • Synthesis of stable ionogel using non-hydrolytic route with reduced precursor and solvolytic reagent molar ratio. • Ionogels are free from entrapped residual reaction product. • The ionogels synthesized with higher amount of ionic liquids show bulk liquid like electrical behaviour.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Ionic ASi{sub 2}N{sub 3} (A=Li, Na, K and Rb) stabilized by the covalent Si–N bonding: First-principles calculations

The structural, elastic and electronic properties of LiSi{sub 2}N{sub 3} and its substitutions by Na, K and Rb were investigated through first-principles computations. The expansion of lattice parameters of ASi{sub 2}N{sub 3} from Li, Na, K to Rb is found to be determined by the bond angle of Si–N1–Si, which suggests a possible way to improve the lithium ionic conductivity by substitutions. ASi{sub 2}N{sub 3} (A=Li, Na, K and Rb) shows the similar elastic behaviors, while the electronic band gap gradually decreases from 5.1 to 3.4 eV from LiSi{sub 2}N{sub 3} to RbSi{sub 2}N{sub 3}. Interestingly, the analysis of electronic structure, crystal orbital Hamiltonian populations and Bader charges shows that the covalence of Si–N bonding is critical for the stability of ASi{sub 2}N{sub 3} phase. Among ASi{sub 2}N{sub 3} phases, there is a relatively high ionicity in NaSi{sub 2}N{sub 3}; the Si–N bond strength in [Si{sub 2}N{sub 3}]{sup −} net for KSi{sub 2}N{sub 3} and RbSi{sub 2}N{sub 3} is comparable to LiSi{sub 2}N{sub 3}, but stronger than NaSi{sub 2}N{sub 3}. - Graphic abstract: Universal trend of structural and electronic properties in alkaline metal silicon nitrides, ASi{sub 2}N{sub 3}, A=Li, Na, K and Rb. - Highlights: • Trend in structure, electronic and mechanical properties of ASi{sub 2}N{sub 3} (A=Li-Rb) were predicted. • Lattice expansion of ASi{sub 2}N{sub 3} induced by the bond angle of Si–N1–Si was found. • Calculated band gap decreases from 5.1 to 3.4 eV from LiSi{sub 2}N{sub 3} to RbSi{sub 2}N{sub 3}. • Covalent Si–N bonding is critical for the stability of ASi{sub 2}N{sub 3}.

36 MATERIALS SCIENCE↗
DOE OSTI2015

Humidity Effect on Nanoscale Electrochemistry in Solid Silver Ion Conductors and the Dual Nature of Its Locality

Scanning probe microscopy (SPM) is a powerful tool to investigate electrochemistry in nanoscale volumes. While most SPM-based studies have focused on reactions at the tip-surface junction, charge and mass conservation requires coupled and intrinsically non-local cathodic and anodic processes that can be significantly affected by ambient humidity. Here, we explore the role of water in both cathodic and anodic processes, associated charge transport, and topographic volume changes depending on the polarity of tip bias. The first-order reversal curve current-voltage technique combined with simultaneous detection of the sample topography, referred to as FORC-IVz, was applied to a silver solid ion conductor. We found that the protons generated from water affect silver ionic conduction, silver particle formation and dissolution, and mechanical integrity of the material. This work highlights the dual nature (simultaneously local and non-local) of electrochemical SPM studies, which should be considered for comprehensive understanding of nanoscale electrochemistry.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2016

Electrospun montmorillonite modified poly(vinylidene fluoride) nanocomposite separators for lithium-ion batteries

Highlights: • Composite separators of PVDF and MMT for lithium-ion batteries were electrospun. • Thermal dimensional stability and tensile property of composite separators get improved. • Presence of montmorillonite promotes electrical properties of PVDF fibrous separators. • Batteries consisting of PVDF/MMT-5% separator achieve the best performance. - Abstract: Composite separators of poly(vinylidene fluoride) (PVDF) with different contents of montmorillonite (MMT) for Li-ion batteries have been fabricated by electrospinning. The morphology, function group, crystallinity, and mechanical properties of membranes were investigated by scanning electron microscope (SEM), Fourier Transform infrared spectra (FT-IR), differential scanning calorimetry (DSC), and tensile test, respectively. Interlayer spacing of MMT in polymer was characterized by X-ray diffraction (XRD). In addition, the results of electrochemical measurements suggest that PVDF/MMT-5% composite membrane has maximum ionic conductivity of 4.2 mS cm{sup −1}, minimum interfacial resistance of 97 Ω, and excellent electrochemical stability. The cell comprising PVDF/MMT-5% composite membrane shows higher capacity and more stable cycle performance than the one using commercial Celgard PP membrane.

36 MATERIALS SCIENCE↗
DOE OSTI2018

Crystal Structures, Local Atomic Environments, and Ion Diffusion Mechanisms of Scandium-Substituted Sodium Superionic Conductor (NASICON) Solid Electrolytes

The importance of exploring new solid electrolytes for all-solid-state batteries has led to significant interest in NASICON-type materials. In this work, the Sc 3+ -substituted NASICON compositions Na 3 Sc x Zr 2– x (SiO 4 ) 2- x (PO 4 ) 1+ x (termed N3) and Na 2 Sc y Zr 2- y (SiO 4 ) 1- y (PO 4 ) 2+ y (termed N2) ( x , y = 0–1) are studied as model Na + -ion conducting electrolytes for solid-state batteries. The influence of Sc 3+ substitution on the crystal structures and local atomic environments has been characterized by powder X-ray diffraction (XRD) and neutron powder diffraction (NPD), as well as solid-state 23 Na, 31 P, and 29 Si nuclear magnetic resonance (NMR) spectroscopy. A phase transition between 295 and 473 K from monoclinic C 2/ c to rhombohedral $R\bar{3}c$ is observed for the N3 compositions, while N2 compositions crystallize in a rhombohedral $R\bar{3}c$ unit cell in this temperature range. Alternating current (AC) impedance spectroscopy, molecular dynamics (MD), and high temperature 23 Na NMR studies are in good agreement, showing that, with a higher Sc 3+ concentration, the ionic conductivity (of about 10 -4 S/cm at 473 K) decreases and the activation energy for ion diffusion increases. 23 Na NMR experiments indicate that the nature of the Na + -ion motion is two-dimensional on the local atomic scale of NMR although the long-range diffusion pathways are three-dimensional. In addition, a combination of MD, bond valence, maximum entropy/Rietveld, and van Hove correlation methods has been used to reveal that the Na + -ion diffusion in these NASICON materials is three-dimensional and that there is a continuous exchange of sodium ions between Na(1) and Na(2) sites.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2026

Computational simulation of asymmetric phase transformation in cracked Li₇La₃Zr₂O₁₂: Variant selection and chemo-mechanical implications

Coupling between microcracks and phase transformation in ion-conducting ceramics can jointly affect mechanical responses and ion transport. In this work we investigate the cubic-to-tetragonal phase transformation in Li₇La₃Zr₂O₁₂ in the presence of a microcrack under hydrostatic loading and quantify its implications for crack-tip stress concentration and Li-ion transport using phase-field and molecular dynamics simulations. The phase transformation exhibits a strong asymmetry between hydrostatic tension and compression. Under tension, the crack edge nucleates one tetragonal variant that amplifies the crack-tip stress intensity and promotes crack opening. Under compression, the crack tip nucleates a different tetragonal variant that enhances the stress-induced crack-closure tendency. Effective Li diffusivity analysis shows faster transport degradation under compression due to accelerated transformation kinetics, exposing a trade-off between mechanical stability and ionic conductivity. These results highlight the intertwined nature of cracking, phase transformation, and ionic transport in ion-conducting oxides and provide mechanistic insights into chemo-mechanical degradation of solid electrolytes.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Structural and electrochemical properties of PEMA with the influence of MWCNT / TiO{sub 2} filler

An attempt has been made to prepare a hybrid Nano composite polymer electrolytes (NCPES) based on Poly(ethyl methacrylate) (PEMA) doped with multiwalled carbon nanotubes (MWCNT) and Titanium oxide (TiO{sub 2}) as additives, Lithium per chlorate (LiClO{sub 4}) as ionic salt and Propylene Carbonate as plasticizer (PC) by using solvent casting technique. X-ray diffraction analysis (XRD) confirms the miscibility and amorphous nature of the prepared electrolytes. It has been found from the a.c impedance analysis that the inorganic filler reduces the bulk resistance of the electrolytes and thus ionic conductivity enhanced. A high dielectric loss value is observed for the case of doped MWCNT-PEMA in comparison with pure PEMA and doped TiO{sub 2} –PEMA membranes. Based on the study of relaxation spectra, it is found that the relaxation time decreases with increase in temperature.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2018

Effect of Na substitution for La on Li ion conductivity of Li5La3Nb2O12 garnets by sol–gel process

Highlights: • The effect of Na substitution for La on Li ion conductivity in the Li5La3Nb2O12 solid state electrolyte is reported. • The power XRD patterns reveal that the partial substitutions of Na for La in Li{sub 5+2x}La{sub 3-x}Na{sub x}Nb{sub 2}O{sub 12} electrolytes are isostructural. • The new solid state electrolyte is very stable in potential range of −0.8 to 5.0V vs. Li/Li+. - Abstract: In this paper, the effect of Na substitution for La on Li ion conductivity in the well-known Li{sub 5}La{sub 3}Nb{sub 2}O{sub 12} parents with the cubic garnet framework prepared by sol-gel process is reported. The optimum condition is at 750 °C for 6 h in air with 10% excess lithium salt. The power XRD patterns reveal that the partial substitutions of Na for La in Li5 + 2{sub x}La{sub 3-x}Na{sub x}Nb{sub 2}O{sub 12} electrolytes are isostructural. The cubic lattice parameters decrease as the molar fractions of Na increasing. Among the Li5 + 2{sub x}La{sub 3-x}Na{sub x}Nb{sub 2}O{sub 12} compounds investigated, the Na-substituted Li{sub 6.4}La{sub 2.3}Na{sub 0.7}Nb{sub 2}O{sub 12} exhibits the highest ionic conductivity of 1.6 × 10{sup −4} S cm{sup -1} at room temperature with an activation energy of 0.41 eV. The new solid state electrolyte is very stable in potential range of −0.8 to 5.0 V vs. Li/Li{sup +}, and is also chemically stable against LiMn{sub 2}O{sub 4} and LiCoO{sub 2} compounds up to 900 °C, indicating that Li{sub 6.4}La{sub 2.3}Na{sub 0.7}Nb{sub 2}O{sub 12} is a promising solid state electrolyte for all-solid-state battery application.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2023

Tuning Transport via Interaction Strength in Cationic Conjugated Polyelectrolytes

Tuning polymer-ion interaction strength is critical for balancing ion solvation and transport in solid polymer electrolytes for battery applications. In mixed Li + /electron conducting systems for improved battery binders, the design space is further complicated by seemingly opposing design rules for electron and ion conducting polymers. Conjugated polymers functionalized with cationic side chains have demonstrated high ionic conductivity, lithium transport, and electronic conductivity by combining long-range polymer ordering with diffuse ion interactions. Herein, we demonstrate a family of mixed conducting polythiophenes functionalized with a range of cationic side chains, namely imidazolium, trimethylammonium, and ammonium groups. The strength of ionic interactions and structure of the side chains govern lithium-selective transport, resulting in high Li + conductivity (~10 –4 S/cm at 80 °C) and electronic conductivity. The more diffuse imidazolium ion affords labile ionic interactions, resulting in higher lithium transference than the other cations studied. Electronic conductivity is also higher in the imidazolium system, stemming from the ability of the planar side chains to stack while also accommodating the bulky TFSI – counterions. Finally, these results demonstrate the importance of interaction strength in ion transport while also indicating that the physical structure of the side chain has an impact on electronic conduction. The imidazolium group strikes a balance, achieving superior properties across all metrics.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Hybrid Li-S pouch cell with a reinforced sulfide glass solid-state electrolyte film separator

Here, in this paper, sulfide glass electrolyte powder with a nominal composition of (Li 2 S) 60 (SiS 2 ) 28 (P 2 S 5 ) 12 is hot pressed at a 330°C and 12 MPa into separator films using non-woven fiberglass reinforcement. The reinforced separator films are 93% dense, bendable, and have an ionic conductivity of 0.7 mS/cm at room temperature. When integrated into hybrid Li-S coin cells with liquid electrolyte, these reinforced glass separators blocked the parasitic polysulfide shuttle sufficiently to enable reversible cycling without LiNO 3 co-salt. Furthermore, the scalability of the reinforced glass separator technology is demonstrated by assembling and testing a hybrid single-layer pouch cell.

25 ENERGY STORAGE↗
DOE OSTI2016

Structural and impedance studies of LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} synthesized by sol-gel method

LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} is synthesized by sol-gel method by using succinic acid as chelating agent. X-ray diffraction pattern confirms the material is spinel cubic structure with Fd3m space group. Impedance spectroscopy analysis of spinel LiNi{sub 0.5}Mn{sub 1.5}O{sub 4} was performed under a wide frequency and temperature range of 50 Hz to 5 MHz and 303 K to 783 K respectively. The hopping of the electrons, ionic conductivity and activation energy were analyzed from the relaxation frequency of the imaginary impedance (Z”). The activation energy E{sub a} is calculated from the Arrhenius plots and it is found to be 0.3713 eV, which indicates the existence of oxygen vacancy in the material. Nyquist plot indicates the presence of grain effect in the material and suppression in the grain effect is observed with increasing temperature.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
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 OSTI2018

Practical Challenges and Future Perspectives of All-Solid-State Lithium-Metal Batteries

The fundamental understandings and technological innovations in lithium-ion batteries are essential for delivering high energy density, stable cyclability, and cost-effective energy storages with the growing demands in the applications of electrical vehicles and smart grid. Solid-state electrolytes (SSEs) are more promising than organic liquid electrolyte in terms of excellent safety in developing lithium-metal anode as well as other high-capacity cathode chemistries, such as sulfur and oxygen. Considerable efforts have been made to give birth to the superionic conductors with ionic conductivities higher than 10 –3 S cm –1 at room temperature. Furthermore, the high interfacial impedances from the poor compatibility of SSEs with electrodes limit their practical applications, which are discussed in this review. Furthermore, the recent advances and critical challenges for all-solid-state lithium-metal batteries based on the cathode materials of lithium-intercalation compounds, sulfur, and oxygen are overviewed, and their future developments are also prospected.

25 ENERGY STORAGE↗