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DOE OSTI2022

Investigating dry room compatibility of sulfide solid-state electrolytes for scalable manufacturing

All-solid-state batteries (ASSBs) are viewed as promising next-generation energy storage devices, due to their enhanced safety by replacing organic liquid electrolytes with non-flammable solid-state electrolytes (SSEs). The high ionic conductivity and low Young's modulus of sulfide SSEs make them suitable candidates for commercial ASSBs. Nevertheless, sulfide SSEs are generally reported to be unstable in ambient air. Moreover, instead of gloveboxes used for laboratory scale studies, large scale production of batteries is usually conducted in dry rooms. Thus, this study aims to elucidate the chemical evolution of a sulfide electrolyte, Li 6 PS 5 Cl (LPSCl), during air exposure and to evaluate its dry room compatibility. When LPSCl is exposed to ambient air, hydrolysis, hydration, and carbonate formation can occur. Moreover, hydrolysis can lead to irreversible sulfur loss and therefore LPSCl cannot be fully recovered in the subsequent heat treatment. During heat treatment, exposed LPSCl undergoes dehydration, decomposition of carbonate species, and reformation of the LPSCl phase. Lastly, LPSCl was found to exhibit good stability in a dry room environment and was subject to only minor conductivity loss due to carbonate formation. The dry room exposed LPSCl sample was tested in a LiNi 0.8 Co 0.1 Mn 0.1 O 2 |LiIn half-cell, exhibiting no significant loss of electrochemical performance compared with the pristine LPSCl, proving it to be compatible with dry room manufacturing processes.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Moisture Stability of Sulfide Solid-State Electrolytes

In this report we detail a comprehensive study on the moisture stability of sulfide solid-state electrolytes in dry room environments. Although sulfide SSEs have many favorable attributes, this class of materials suffers from poor stability with water. Sulfide SSEs react with water to form gaseous H 2 S and a variety of solid byproducts like Li 3 PO 4 and LiOH, which go on to increase the interfacial impedance of solid-state batteries. Lab-scale research typically utilizes gloveboxes with <1 ppm water, however, the large-scale manufacturing of Li-ion batteries occurs in –40°C dewpoint dry rooms with around 126 ppm water. Consequently, the moisture stability of sulfide SSEs must be addressed if the manufacture of solid-state batteries based on sulfide SSEs is to be scaled up. Here, we are the first to characterize the moisture stability of sulfide SSEs according to both H 2 S and the degradation of ionic conductivity at different moisture setpoints ranging from –76°C to –40°C dewpoint. A variety of different SSE compositions are studied; namely, (Li 2 S) 75 (P 2 S 5 ) 25 , (Li 2 S) 70 (P 2 S 5 ) 30 , (Li 2 O) 7 (Li 2 S) 68 (P 2 S 5 ) 25 , (Li 2 O) 7 (Li 2 S) 63 (P 2 S 5 ) 30 , and (Li 2 S) 75 (P 2 S 5 ) 25 + 20 mol% LiI. We find that moisture stability improves with 75 mol% Li2S modifier content and the introduction of a Li 2 O co-modifier. After a 30 min exposure in a –40°C dewpoint dry room environment we found that (Li 2 S) 75 (P 2 S 5 ) 25 + 20 mol% LiI powder generated 0.1 cc/g H 2 S and its ionic conductivity decreased by over 50%. However, when SSE powder was exposed as a slurry in a dodecane carrier the same SSE composition generated 0 cc/g H 2 S and its ionic conductivity only dropped by 14%. Our results show that sulfide SSEs have acceptable moisture stability when appropriately processed in a dry room environment.

25 ENERGY STORAGE↗

DOE OSTI2024

4.6 V Moisture‐Tolerant Electrolytes for Lithium‐Ion Batteries

Abstract Commercial LiPF 6 ‐based electrolytes face limitations in oxidation stability (4.2 V) and water tolerance (10 ppm). While replacing LiPF 6 with lithium bis(trifluoromethane)sulfonimide (LiTFSI) improves water tolerance, it induces Al current collector corrosion above 3.7 V vs. Li/Li + . To address this, lithium cyano(trifluoromethanesulfonyl)imide (LiCTFSI) is proposed here as a non‐corrosive, moisture‐tolerant alternative. The 2.0 M LiCTFSI/propylene carbonate (PC)‐fluoroethylene carbonate (FEC) (7:3 by volume) electrolyte enables LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811) cathodes to reach 210 mAh g −1 (2.8‐4.6 V) with a cycle life of 500. Full cells with NCM811||graphite (2.0 mAh cm −2 ) show 77.8% capacity retention after 500 cycles. Even with 2000 ppm moisture in the electrolyte, full cells maintain high cycling stability, reducing the need for costly dry rooms. The electrolyte’s low freezing point and high thermal stability enable the operation from ‐20 °C to 60 °C, delivering 168 mAh g −1 at ‐20 °C and retaining 94% capacity after 100 cycles at 60 °C. In contrast, cells with commercial LiPF 6 electrolyte deliver 71 mAh g −1 at ‐20°C and retain 52.7% after 100 cycles at 60 °C. This novel salt offers a cost‐effective solution for developing robust, high‐performance batteries suitable for extreme conditions.

Zhang, Nan↗

DOE OSTI2021

Life‐Cycle Assessment Considerations for Batteries and Battery Materials

Abstract Rechargeable batteries are necessary for the decarbonization of the energy systems, but life‐cycle environmental impact assessments have not achieved consensus on the environmental impacts of producing these batteries. Nonetheless, life cycle assessment (LCA) is a powerful tool to inform the development of better‐performing batteries with reduced environmental burden. This review explores common practices in lithium‐ion battery LCAs and makes recommendations for how future studies can be more interpretable, representative, and impactful. First, LCAs should focus analyses of resource depletion on long‐term trends toward more energy and resource‐intensive material extraction and processing rather than treating known reserves as a fixed quantity being depleted. Second, future studies should account for extraction and processing operations that deviate from industry best‐practices and may be responsible for an outsized share of sector‐wide impacts, such as artisanal cobalt mining. Third, LCAs should explore at least 2–3 battery manufacturing facility scales to capture size‐ and throughput‐dependent impacts such as dry room conditioning and solvent recovery. Finally, future LCAs must transition away from kg of battery mass as a functional unit and instead make use of kWh of storage capacity and kWh of lifetime energy throughput.

25 ENERGY STORAGE↗

DOE OSTI2022

Lithium-Ion Batteries with Safer Current Collectors

The US Department of Energy’s Oak Ridge National Laboratory and Soteria Battery Innovation Group collaborated to develop a metallized polymer film as a current collector for lithium-ion batteries and design slit patterns for electrodes to improve battery safety. The metallized polymer film serves as a fuse that will break under high temperature resulting from a short circuit. Consequently, the short circuit will be broken and the heat generated from the short circuit will be alleviated to avoid thermal runaway. The electrodes with slit patterns are expected to be broken into small segments upon mechanical impact, which can isolate the damaged electrodes from the rest. Thus, the heat generation associated with the mechanical impact will be reduced, along with the likelihood of thermal runaway. This effort aimed to improve lithium-ion battery safety by replacing traditional metal foils with metallized polymer films as current collector and introducing slit patterns to battery electrodes. The metallized polymer films were polyethylene terephthalate with a thin metal (aluminum for cathodes and copper for anodes) coating on both sides. Slit patterns with various geometries and dimensions were designed via simulation. Temperature distribution on cells with electrodes with and without slit patterns was also simulated via nemerical modeling. Electrodes on traditional metal foils and metallized polymer films were coated via a pilot-scale slot-die coater at the US Department of Energy Battery Manufacturing Facility at Oak Ridge National Laboratory. The electrodes were calendered to 35% porosity and punched out with and without slit patterns. Pouch cells were assembed with the electrodes inside a dry room for electrochemical and safety testing. Electrodes coated on metallized polymer films exhibited comparable electrochemical performance to their counterparts coated on traditional metal foils. They also showed improved safety in nail penetration and indentation tests.

25 ENERGY STORAGE↗

DOE OSTI2023

Hot Pressing of Reinforced Li-NMC All-Solid State Batteries with Sulfide Glass Electrolyte

The performance of solid-state batteries (SSBs) with sulfide solid-state electrolytes (SSEs) is limited because they are 10 - 30% porous. Porosity limits energy density of the composite cathode and provides a conduit for Li-metal deposits through the separator if operating specifications (e.g. current density, operating temperature, and pressure) are not strictly controlled. This project focused on demonstrating that hot press cell processing and appropriately formulated sulfide glass SSEs can help eliminate porosity to enable SSBs with energy density of ≥ 350 Wh/kg. The objective of the project was to research, develop, and test SSBs capable of achieving program performance metrics by implementing appropriately formulated sulfide glass SSEs and hot press cell processing in a dry room environment. In the composite cathode, hot pressing helps eliminate porosity to increase energy density by enabling thick composite cathodes with high active material loading. In the separator, hot pressing helps eliminate porosity that may otherwise provide a conduit for Li metal deposits to short the cell.

25 ENERGY STORAGE↗

DOE OSTI2023

Importance of the Heat Treatment Scheme on Self-Reducing Reactive Silver Inks

Self-reducing reactive silver inks can print high-quality silver at reasonable temperatures. While numerous studies have explored the impact of processing temperature on electrical properties, the role of the heat treatment scheme has not yet been studied. Common heat treatment schemes include printing and drying inks at room temperature before heat treatment, performing heat treatments while the inks are still wet, and directly printing the inks onto heated substrates. Each scheme generates distinct heat transfer and mass transport kinetics that can affect the silver morphology and electrical properties. However, to date, the impact of different schemes has not been systematically investigated. To address this knowledge gap, this work investigates how different heat treatment schemes impact metal formation, sintering, and the resultant electrical properties of printed self-reducing reactive silver inks. Heat treatment on room-temperature dried inks and wet inks, with top-down (oven) and bottom-up (hot plate) heating sources, were compared. Inks dried at room temperature resulted in extremely porous films that required high heat treatment temperatures (>100 °C) for silver densification. However, these dried films could only densify locally, and their high initial porosities resulted in voids and high resistances (~0.6 Ω mm –1 ) even after heat treatments above 300 °C. Inks that were wet during heat treatment showed moderate improvements in electrical properties with resistances on the order of 0.4 Ω mm –1 at heat treatments of 250 °C. Printing reactive inks directly onto heated substrates yielded the best low-temperature results, with 0.46 Ω mm –1 (5.5 × bulk silver) line resistances achieved at only 90 °C. Overall, this work’s experimental results provide detailed insights into why printing onto a heated substrate results in superior electrical performance compared to more common heat treatment schemes. Additionally, controlling where the precipitation reaction occurs is critical to controlling the film morphology and properties. As a result, this work shows that even an ammonia-based silver reactive ink can achieve good, low-temperature electrical properties with the proper heat treatment scheme.

14 SOLAR ENERGY↗

DOE OSTI2021

In-situ proton radiation testing of 2.4 micron wavelength extended InGaAs photodiodes at dry ice and room temperatures

We have successfully tested 290 µm diameter, 2.4 micron wavelength, Extended InGaAs photodiodes coupled with single mode fiber using 50 MeV Protons at both dry ice temperature (-72 °C) and room temperature (20 °C). The devices were reverse biased at 100 mV during the radiation run and their leakage current was continuously monitored insitu during the exposure. These devices find multiple applications in space for spectroscopy & sensing, inter-satellite optical communication links, rapid Doppler shift LIDAR, as well as inter-planetary and Earth-to-Moon communication links. Several photodiodes were tested using 50 MeV Protons with an average flux level of 2.11 × 10 7 protons/cm 2 /s, for a total fluence of 1.0 × 10 11 protons/cm 2 and total dose of 20 krad (water). Pre- and post-radiation results were also measured for leakage current vs. voltage, responsivity (quantum efficiency), and bandwidth of the Extended InGaAs photodiodes. Finally, all devices were found to be fully functional at normal operating conditions and at both dry ice and room temperature.

2.4 micron wavelength↗

DOE OSTI2024

Cellulose crystallinity index (CrI) of switchgrass measured by solid-state NMR

Here we present a curated dataset of switchgrass cellulose crystallinity index (CrI) measured using solid state nuclear magnetic resonance (NMR) spectroscopy. Seventy-two topline switchgrass lines grown in greenhouse were collected and ground to -20/+80 mesh. The switchgrass was then Soxhlet-extracted with toluene/ethanol for 24 h to remove extractives. The extractives-free switchgrass was holopulped by using peracetic acid at 5 g loading per g biomass and the solution consistency was adjusted to 5% with DI water. Holopulping was conducted at room temperature for 24 h with stirring. The obtained holocellulose was washed excessively with DI water and air-dried at room temperature for 24 h. The dried holocellulose was treated with hydrochloric acid (2.5 M) for 2 h to remove hemicellulose. The isolated cellulose was collected by filtration, rinsed with DI water, and used to analyze cellulose crystallinity by solid-state NMR. The NMR samples were prepared by packing the moisturized cellulose into 4-mm cylindrical Zirconia MAS rotors. Cross polarization/magic angle spinning (CP/MAS) NMR analysis of cellulose was carried out on a Bruker Avance III 400-MHz spectrometer operating at 100.59 MHz for 13C in a Bruker double-resonance MAS probe head at spinning speeds of 8 kHz. The CP/MAS experiments utilized a 5 ms (90°) proton pulse, 1.5 ms contact pulse, 4 s recycle delay and 4000 scans. The cellulose crystallinity index was determined from the areas of the cellulose crystalline C4 signal (δ 86-92 ppm) over the entire C4 regions (δ 79-92 ppm) in the NMR spectra.

Cellulose, crystallinity index, switchgrass, solid↗

DOE OSTI2022

Monolayer Plasmonic Nanoframes as Large‐Area, Broadband Metasurface Absorbers

Abstract Broadband absorbers are useful ultraviolet protection, energy harvesting, sensing, and thermal imaging. The thinner these structures are, the more device‐relevant they become. However, it is difficult to synthesize ultrathin absorbers in a scalable and straightforward manner. A general and straightforward synthetic strategy for preparing ultrathin, broadband metasurface absorbers that do not rely on cumbersome lithographic steps is reported. These materials are prepared through the surface‐assembly of plasmonic octahedral nanoframes (NFs) into large‐area ordered monolayers via drop‐casting with subsequent air‐drying at room temperature. This strategy is used to produce three types of ultrathin broadband absorbers with thicknesses of ≈200 nm and different lattice symmetries (loose hexagonal, twisted hexagonal, dense hexagonal), all of which exhibit efficient light absorption (≈90%) across wavelengths ranging from 400–800 nm. Their broadband absorption is attributed to the hollow morphologies of the NFs, the incorporation of a high‐loss material (i.e., Pt), and the strong field enhancement resulting from surface assembly. The broadband absorption is found to be polarization‐independent and maintained for a wide range of incidence angles (±45°). The ability to design and fabricate broadband metasurface absorbers using this high‐throughput surface‐based assembly strategy is a significant step toward the large‐scale, rapid manufacturing of nanophotonic structures and devices.

36 MATERIALS SCIENCE↗

DOE OSTI2021

Additive Manufacturing of Porous Ceramics With Foaming Agent

The macro-porous ceramics has promising durability and thermal insulation performance. As porous ceramics find more and more applications across many industries, a cost-effective and scalable additive manufacturing technique for fabricating macro-porous ceramics is highly desirable. Herein, we reported a facile additive manufacturing approach to fabricate porous ceramics and control the printed porosity. Several printable ceramic inks were prepared, and the foaming agent was added to generate gaseous bubbles in the ink, followed by the direct ink writing and the ambient-pressure and room-temperature drying to create the three-dimensional geometries. In this work, a set of experimental studies were performed to optimize the printing quality. The results revealed the optimal process parameters for printing the foamed ceramic ink with a high spatial resolution and fine surface quality. Varying the concentration of the foaming agent enables the controllability of the structural porosity. The maximum porosity can reach 85%, with a crack-free internal porous structure. The tensile tests showed that the printed macro-porous ceramics possessed enhanced durability with the addition of fiber. With a high-fidelity three-dimensional (3D) printing process and the precise controllability of the porosity, we showed that the printed samples exhibited a remarkably low thermal conductivity and durable mechanical strength.

36 MATERIALS SCIENCE↗

DOE OSTI2022

Adrian Portales Coop Internship Report

Using the thesis of W.R. Nolan (cite) as a guide, Cobalt Iron (CoFe) powders were reacted with 0.1 wt.% and 0.2 wt.% phosphoric acid in a 20:1 ratio of acetone to phosphoric acid. The powders were then dried at room temperature. The resulting phosphate coated CoFe was then mixed with 0.75 wt.% of the lubricant N,N' ethylene bis-stearamide (trade name: Acrawax C) and hot pressed to form a consolidated soft magnetic material referred to as CoFeP. With an avenue of synthesis for CoFeP determined, a proper amount of stock was synthesized for continuous “brick” production. While under current optimization, these 1x1 mm magnetic bricks will ultimately be placed and secured along the inside wall of each MK Magnetics transformer core by an appropriate CoFeP dispersed epoxy. As of now each brick has been produced though a pressing and annealing process via square 2x2 cm die. Before a brick is made a pressure calculation is run to ensure the dies maximum operating pressure is not exceeded. Figure 1. ensures the user’s safety by showing that the tons-on-ram required for a 2x2 cm square die to reach 760 MPa is below the point of die failure.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Cost-Effective Additive Manufacturing of Ambient Pressure-Dried Silica Aerogel

The conventional manufacturing processes for aerogel insulation materials mostly rely on the supercritical drying, which suffers from issues of massive energy consumption, high-cost equipment, and prolonged processing time. Considering the large market demand for the aerogel insulation material in the next decade, a cost-effective and scalable fabrication technique is highly desired. In this paper, a direct ink writing (DIW) method is used to three-dimensionally fabricate the silica aerogel insulation material, followed by room-temperature and ambient pressure drying. Compared with the supercritical drying and freeze-drying techniques, the reported method significantly reduces the fabrication time and costs. The cost-effective DIW technique offers the capability to print complex hollow internal structures, coupled with the porous aerogel structure, it is found to be beneficial for the thermal insulation property. In this work, the addition of fiber to the ink assures the durability of the fabricated product, without sacrificing the thermal insulation performance. The foam ink preparation methods and the printability are demonstrated in this paper, along with the printing of complex three-dimensional geometries. The thermal insulation performance of the printed objects is characterized, and the mechanical properties were also examined. The proposed approach is found to have a 56% reduction in the processing time. The printed silica aerogels exhibit a low thermal conductivity of 0.053 W m –1 K –1 .

36 MATERIALS SCIENCE↗

DOE OSTI2023

Reaction Layer Formation on MgO in the Presence of Humidity

Mineralization by MgO is an attractive potential strategy for direct air capture (DAC) of CO 2 due to its tendency to form carbonate phases upon exposure to water and CO 2 . Hydration of MgO during this process is typically assumed to not be rate limiting, even at ambient temperatures. However, surface passivation by hydrated phases likely reduces the CO 2 capture capacity. Here, we examine the initial hydration reactions that occur on MgO(100) surfaces to determine whether they could potentially impact CO 2 uptake. We first used atomic force microscopy (AFM) to explore changes in reaction layers in water (pH = 6 and 12) and MgO-saturated solution (pH = 11) and found the reaction layers on MgO are heterogeneous and nonuniform. To determine how relative humidity (R.H.) affects reactivity, we reacted samples at room temperature in nominally dry N 2 (~11–12% R.H.) for up to 12 h, in humid (>95% R.H.) N 2 for 5, 10, and 15 min, and in air at 33 and 75% R.H. for 8 days. X-ray reflectivity and electron microscopy analysis of the samples reveal that hydrated phases form rapidly upon exposure to humid air, but the growth of the hydrated reaction layer slows after its initial formation. Reaction layer thickness is strongly correlated with R.H., with denser reaction layers forming in 75% R.H. compared with 33% R.H. or nominally dry N 2 . The reaction layers are likely amorphous or poorly crystalline based on grazing incidence X-ray diffraction measurements. After exposure to 75% R.H. in air for 8 days, the reaction layer increases in density as compared to the sample reacted in humid N 2 for 5–15 min. Further, this may represent an initial step toward the crystallization of the reaction layer. Overall, high R.H. favors the formation of a hydrated, disordered layer on MgO. Based on our results, DAC in a location with a higher R.H. will be favorable, but growth may slow significantly from initial rates even on short timescales, presumably due to surface passivation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2021

Removable smart sequestration coatings for hazardous metals

Materials are disclosed for the safe sequestration and removal of hazardous contaminants from a surface. The materials can be sprayed, rolled, painted, brushed or dip coated onto any surface and allowed to dry and/or cure at room temperature or drying/curing can be accelerated by the application of heat to form a coating that entraps the contaminant therein. The coating and the entrapped contaminant can then peeled from the surface and safely disposed of to minimize hazardous waste. The coating includes a colorimetric additive that is specific to the contaminant, the coating and the contaminant producing a visual indication of contamination.

Sampathkumaran, Uma↗

DOE OSTI2023

Removable smart sequestration coatings for hazardous metals

Sampathkumaran, Uma↗

DOE OSTI2024

Differential Organic Carbon Mineralization Responses to Soil Moisture in Three Different Soil Orders Under Mixed Forested System: Supporting Data

This data contains data from 90-day long incubation study which aimed to look at the soil moisture-texture relationship on soil organic carbon (SOC) cycling. Soils were collected from three distinct soil textures from mixed forests in 2017: sandy (Georgia, 2017-05-01), loamy (Missouri, 2017-06-14) and clayey (Texas, December 2017) were incubated at different soil moisture levels (air-dried, 25% water holding capacity (WHC), 50% WHC, 100% WHC and 175% WHC) at room temperature for a period of 90 days. Files contain microbial respiration, active and slow SOC pools, and their respective mineralization rates, extractable organic carbon (C), and C-acquiring extracellular enzymes. Findings from these data were used in Singh et al. (2021). This study aimed to examine the interactive effect of soil moisture and texture on SOC mineralization. Soil samples of three distinct textures (sandy, loamy, and clayey) were collected from mixed forests of Georgia, Missouri, and Texas, respectively. Soil cores of 5 cm diameter were collected from numerous random locations at each site from 0-15 cm depth after scraping the litter layer and mixed thoroughly to obtain a composite sample per site. Three additional soil cores were collected to determine the WHC using pressure plate extractors. Soil samples were composited, and triplicate soil samples were incubated in mason jars for a period of 90 days at room temperature under different moisture regimes: air dried, 25% WHC, 50% WHC, at WHC and 100% saturation. Soil respiration was measured weekly, and destructive sampling was conducted at 1, 15, 60, and 90 days to determine extractable organic C, C acquiring enzyme activity, and active and slow SOC pools with their respective mineralization rates. The C acquiring enzyme activity was the total activity of α-glucosidase, β-glucosidase, cellobiohydrolase, and β-xylosidase enzymes. Gas samples for microbial respiration measurements were collected from headspace of incubation jars through the sampling ports on the lids and then analyzed using a Shimadzu Gas Chromatograph (GC-2014). Prior to sampling, the vials were evacuated. Blank correction was also done by collecting gas samples from empty incubation jars. Double pool exponential decay model was used in SigmaPlot to determine the active and slow SOC pools and their mineralization rates (Farrar et al., 2012; Jagadamma et al., 2014). The C-acquiring extracellular enzymes were measured using the microplate method by German et al., (2011). Microbial community structure was determined using the phospholipid fatty acid (PLFA) and neutral lipid fatty acid (NLFA) analyses (Buyer and Sasser, 2012). This dataset has seven data files provided in comma-separate (*.csv) format. Additional metadata are provided: seven data dictionaries and a file-level metadata file in comma separate (*.csv) format and a user guide in PDF (*.pdf) format.

Carbon acquiring enzyme activity↗

DOE OSTI2021

Characterization of hot-pressed von Alpen type NASICON ceramic electrolytes

The Na-ion conducting solid electrolyte NASICON is a promising solid state electrolyte (SSE) for use in Na based electrochemical systems. The effects of particle morphology and synthesis of von Alpen type NASICON via hot-pressing were investigated. Spray dried particles were shown to improve mechanical and electrochemical properties. X-ray diffraction, scanning electron microscopy, impulse excitation measurements, Vickers hardness, and impedance spectroscopy were used to correlate relationships between phase purity, microstructure, mechanical properties, and electrochemical properties. Scanning electron microscopy showed the presence of a glass phase as between 19.08% and 28.23% area percentage and a ZrO 2 phase between 0.46% and 3.51% area percentage in the hot-pressed samples. Impulse excitation showed elastic modulus varying from 83.65 to 97.65 GPa. The first values of Poisson's ratio and shear modulus of NASICON are reported as between 0.23 and 0.26 and 33.87 to 38.79 GPa, respectively. Vickers hardness and fracture toughness measurements showed Vickers hardness ranging from 4.30 to 4.68 GPa and fracture toughness ranging from 1.05 to 1.09 MPa m ½ . Impedance spectroscopy showed grain conductivities ranging from 1.023 to 1.287 mS/cm, with grain boundary resistance percentages between 73.22 and 47.5%. Total conductivities ranged from 0.292 to 0.596 mS/cm, with 0.596 mS/cm being achieved at room temperature for the spray dried powders with lower grain boundary resistance percentages.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗