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DOE OSTI2023

Sodium Carbazolide and Derivatives as Solid‐State Electrolytes for Sodium‐Ion Batteries

Abstract Replacing widely used organic liquid electrolytes with solid‐state electrolytes (SSEs) could effectively solve the safety issues in sodium‐ion batteries. Efforts on seeking novel solid‐state electrolytes have been continued for decades. However, issues about SSEs still exist, such as low ionic conductivity at ambient temperature, difficulty in manufacturing, low electrochemical stability, poor compatibility with electrodes, etc. Here, sodium carbazolide (Na‐CZ) and its THF‐coordinated derivatives are rationally fabricated as Na + conductors, and two of their crystal structures are successfully solved. Among these materials, THF‐coordinated complexes exhibit fast Na + conductivities, i.e., 1.20×10 −4 S cm −1 and 1.95×10 −3 S cm −1 at 90 °C for Na‐CZ‐1THF and Na‐CZ‐2THF, respectively, which are among the top Na + conductors under the same condition. Furthermore, stable Na plating/stripping is observed even over 400 h cycling, showing outstanding interfacial stability and compatibility against Na electrode. More advantages such as ease of synthesis, low‐cost, and cold pressing for molding can be obtained. In situ NMR results revealed that the evaporation of THF may play an essential role in the Na + migration, where the movement of THF creates defects/vacancies and facilitates the migration of Na + .

Yu, Yang↗

DOE OSTI2023

Sodium Carbazolide and Derivatives as Solid‐State Electrolytes for Sodium‐Ion Batteries

Yu, Yang↗

DOE OSTI2022

Structural design strategies for superionic sodium halide solid electrolytes

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

25 ENERGY STORAGE↗

DOE OSTI2022

Sodium trithiocarbonate cathode for high-performance sodium–sulfur batteries

The high abundance and low cost of sodium and sulfur make room-temperature sodium-sulfur (RT Na-S) batteries an attractive technology compared to the current lithium-ion batteries for large-scale grid-storage applications. However, the commercialization of RT Na-S batteries is impeded by the slow kinetics of Na-S chemistry, severe sodium polysulfide shuttling, and uncontrollable growth of dendritic Na. Herein, sodium trithiocarbonate (Na 2 CS 3 ) is applied as a cathode material to facilitate concurrent improvement in both electrodes, leading to a high-rate performance with extended cycle life. The conductive characteristic of the carbon-sulfur resonance bond provides fast ion and electron transfer throughout the cathode, resulting in superior electrochemical reactivity. At the cathode, the presence of Na2CS3 forms an oligomer-structured layer to suppress the dissolution and shuttling of active materials. Meanwhile, when small portions of Na 2 CS 3 intermediates migrate to the anode, a stable solid electrolyte interphase (SEI) layer with uniform Na-ion flux is formed, enabling improved Na stripping and plating performance. A series of electrochemical and materials characterization, accompanied by density functional theory calculations demonstrate that Na 2 CS 3 is a promising candidate to realize high-rate performance long cycle life RT Na-S batteries.

25 ENERGY STORAGE↗

DOE OSTI2020

Sodium Ion Expansion Power Block for Distributed CSP

The Sodium Ion Expansion Power Block for Distributed CSP was a three-plus-one-year effort under the Concentrating Solar Power: Advanced Projects Offering Low LCOE Opportunities (CSP: APOLLO) funding program within the U.S. Department of Energy Solar Energy Technologies Office. The primary objective of this project is to develop a dual-stage modular sodium thermal electrochemical converter (Na-TEC) heat engine power block, which can be potentially integrated with either a small-scale dish solar or large-scale heliostats and parabolic trough CSP. Na-TEC is a heat engine that generates electricity through the isothermal expansion of sodium ions. The Na-TEC is a closed system that can theoretically achieve conversion efficiencies above 45% when operating between thermal reservoirs at 1150 K and 550 K. However, thermal designs have confined previous single-stage devices to thermal efficiencies below 20%. To mitigate some of these limitations, we consider dividing the isothermal expansion into two stages; one at the evaporator temperature (1150 K) and another at an intermediate temperature (650 K –1050 K). This dual-stage Na-TEC takes advantage of regeneration and reheating, and could be amenable to better thermal management. In light of this, we first designed and developed a thermo-electrochemical model, and thermodynamically demonstrated how the dual-stage device can improve the efficiency by up to 8% points over the best performing single-stage device. We also established an application regime map for the single- and dual-stage Na-TEC in terms of the power density and the total thermal parasitic loss. Moreover, a thermal design of an axisymmetric dual-stage Na-TEC is developed to guide the scale-up and fabrication of sub-components of prototype module. A reduced-order finite-element model is used in conjunction with a Na-TEC thermodynamic model that was developed to determine the total parasitic heat loss of this dual-stage design. A number of simplifications are applied in the reduced-order model to decrease the computational time while maintaining acceptable accuracy. According to this analysis, a maximum efficiency of 29% and a maximum power output of 125 W can be achieved. Ultimately, we were able to demonstrate thermal efficiency improvements of the Na-TEC heat engine from 19% up to 40.3%, in a dual-stage (non-optimized) prototype module that we designed, fabricated, and tested with high temperature stage at 923 K. Furthermore, a cost-performance analysis for this improved dual-stage design was carried out for distributed-CSP systems. A high-level techno-economic analysis (TEA) explores four scenarios where a Na-TEC is used as the heat engine for a distributed-CSP system. Overnight capital cost and levelized cost of electricity (LCOE) are estimated for a system lifetime of 30 years, revealing that overnight capital costs in a range from $3.57 to $17.71 per We are feasible, which equate to LCOEs from 6.9 to 17.2 cents/kWh e -1 . This analysis makes a significant contribution by concurrently quantifying the efficiency and unit costs for a range of multistage configurations, and demonstrating that a Na-TEC may be a promising alternative to Stirling engines for distributed-CSP systems at residential scale of 1–5 kW e .

14 SOLAR ENERGY↗

DOE OSTI2023

Hawai‘i Play Fairway (Final Report)

Most of Hawai'i's geothermal resources are blind—their manifestations, such as hot springs and steam vents, do not appear on the ground surface because the heated water flows far below. With the exception of $K\bar{i}lauea East Rift Zone$, in most areas of Hawai'i, high lateral permeability in the first kilometer below ground surface prevents surface thermal features from developing. As a methodology for discovering these blind resources, Play Fairway Analysis (PFA) involves finding potential locations of blind hydrothermal systems and describing potential geothermal sources in rift-zone settings. Using the PFA to find Hawai'i's geothermal resources, the University of Hawai'i (UH) conducted the Hawai‘i Play Fairway Project, Hawai'i's first statewide geothermal resource assessment since 1985. Sponsored by the U.S. Department of Energy, the Hawai'i Play Fairway Project provided an updated resource assessment, a roadmap for additional exploration activities, and the identification of areas for further exploration. Benefitting from UH's core competency in earth sciences and experienced geothermal researchers, the project comprised three phases. During the first phase, the team identified, compiled, and ranked existing geologic, groundwater, and geophysical datasets relevant to subsurface heat, fluid and permeability. Using a Bayesian statistical approach, the team developed a statistical methodology to integrate these data into a resource probability map. The team evaluated the confidence in the probability value and considered development viability of areas with geothermal resources. With these analyses, the team identified 10 locations in the Hawaiian Islands for exploration activities. For the second phase, the team collected new groundwater data in 10 locations across the state and new geophysical data on $L\bar{a}na‘i, Maui$, and central Hawai'i Island and modeled topographically induced stress to better characterize subsurface permeability. Analyzing the subsurface stresses, the team evaluated the potential for fracture-induced permeability. The team inverted the MT and gravity data to produce 3D models of resistivity and density, respectively, on $L\bar{a}na‘i$, across $Haleakal\bar{a}'s$ SW rift (Maui), and surrounding Mauna Kea (Hawai‘i Island). The team developed and applied a new method for incorporating depth information about resistivity, density, and potential for fracture-induced permeability into the statistical method for computing resource probability in these three focus areas. The team incorporated the new groundwater results with the new geophysical results and the calculations of potential for fracture-induced permeability to produce updated maps of resource probability and confidence. Through combining data from the first and second phases, the team determined locations for further exploration during the third phase. For MT and gravity surveys, the team recommended $Kaua'i's$ $L\bar{i}hu'e$ $Basin$, the east rift of $Maui's$ $Haleakal\bar{a}$ volcano, and the southwest rift of Hawai'i Island's Mauna Loa volcano. The MT and gravity surveys aimed to enable improved confidence in the resource potential in these locations. For drilling deep groundwater well(s), the team recommended Southeast Mauna Kea and $L\bar{a}na's$ $P\bar{a}l\bar{a}wai$ $Basin$. During the third phase, further exploration involved drilling a groundwater well in $L\bar{a}na's$ $P\bar{a}l\bar{a}wai$ $Basin$ and performing more geophysical surveys. We deepened an existing water well proximal to our target area on $L\bar{a}na'i$ due to funding constraints that precluded us from spudding a new well that would exceed 1km depth. Drilling was preceded by a number of substantial elements including: writing an Environmental Assessment and the subsequent legal process, performance of deviation logging, lowering a camera down the well, coordinating site preparation with $P\bar{u}lama$ $L\bar{a}na'i$, shipping the UH-owned rig interisland, procuring supplies, and leading 3 community meetings on $L\bar{a}na'i$. Drilling occurred 24/7 the entire month of June 2019 over which time $L\bar{a}na'i$ $Well$ 10 was deepened from 427 m to 1057 m, with continuous core collected. We measured a roughly linear temperature gradient averaging 42°C/km and a maximum bottom hole temperature of 66°C. This gradient is more than twice the background for Hawai'i and within a range of gradients measured in this depth range for some exploration wells within KERZ. We consider these results encouraging for $L\bar{a}na'i's$ resource potential and recommend following with a slim hole within $L\bar{a}na'i's$ caldera (our target zone) to ~ 2 km. Further, the positive implications such results have for the island of O‘ahu are substantial - the shield stage of O'ahu's volcanoes ended 1-2 My earlier. However, O'ahu uses more electricity than the rest of the islands combined, and the utility recently called for 500-700MW of firm, dispatchable renewable electricity on O'ahu by 2033. In Phase 3, we also collected limited new encouraging groundwater data, and updated our thoughts on the probabilities of fluid and permeability at resource depths (Pr F = 1; Pr P = mostly unconstrained). Ultimately, we advocate for using our final probability of heat, and confidence in this probability, to drive the next phase of exploration. We contend further development of geothermal in Hawai‘i will enable the state to achieve its 100% renewable policy objective and Hawai'i to transition off of fossil fuels through geothermal discovery and development. The project not only produced a large amount of data and expanded the existing knowledge of Hawai'i's geothermal resources, but also produced publications, theses, presentations, core photos, datasets, media reports, television interviews, community events, and a blog. Students and new professionals benefitted from the project's hands-on research experiences and educational opportunities and earned awards and recognition.

15 GEOTHERMAL ENERGY↗

DOE OSTI2021

Recent Progress in Cathode Materials for Sodium-Metal Halide Batteries

Transitioning from fossil-fuels to renewable energy sources is a critical goal of greenhouse gas re-duction and climate control. Major improvements have made wind and solar power increasingly cost-competitive with fossil fuels. However, the inherent intermittency of renewable power sources such motivates pairing these resources with energy storage. Electrochemical energy storage in batteries is widely used in many fields and increasingly for grid-level storage, but current battery technologies still fall short of performance, safety, and cost. This review focuses on sodium metal halide (Na-MH) batteries, such as well-known Na-NiCl2 batteries, as a promising solution to safe and economical grid-level energy storage. Important features of conventional Na-MH batteries are discussed, and recent literature on the development of intermediate temperature, low-cost cathodes for Na-MH batteries is highlighted. By employing lower cost metal halides (e.g. FeCl2, ZnCl2, and CuCl2, etc.) in the cathode and operating at lower temperatures (e.g. 190 °C vs. 280 °C), new Na-MH batteries have the potential to offer comparable performance at much lower overall costs, providing an exciting alternative technology to enable widespread adoption of renewables plus storage for the grid.

Zhan, Xiaowen↗

DOE OSTI2022

Determination of Sodium Abundance Ratio from Low-resolution Stellar Spectra and Its Applications

We present a method to determine sodium abundance ratios ([Na/Fe]) using the Na i D doublet lines in low-resolution (R ~ 2000) stellar spectra. As stellar Na i D lines are blended with those produced by the interstellar medium, we developed a technique for removing the interstellar Na I D lines using the relationship between extinction, which is proportional to E(B – V), and the equivalent width of the interstellar Na i D absorption lines. When measuring [Na/Fe], we also considered corrections for nonlocal thermodynamic equilibrium (NLTE) effects. Comparisons with data from high-resolution spectroscopic surveys suggest that the expected precision of [Na/Fe] from low-resolution spectra is better than 0.3 dex for stars with [Fe/H] > –3.0. We also present a simple application employing the estimated [Na/Fe] values for a large number of stellar spectra from the Sloan Digital Sky Survey (SDSS). After classifying the SDSS stars into Na-normal, Na-high, and Na-extreme, we explore their relation to stars in Galactic globular clusters (GCs). We find that while the Na-high SDSS stars exhibit a similar metallicity distribution function (MDF) to that of the GCs, indicating that the majority of such stars may have originated from GC debris, the MDF of the Na-normal SDSS stars follows that of typical disk and halo stars. As there is a high fraction of carbon-enhanced metal-poor stars among the Na-extreme stars, they may have a non-GC origin, perhaps due to mass-transfer events from evolved binary companions.

79 ASTRONOMY AND ASTROPHYSICS↗

DOE OSTI2021

Phase-Transition Interlayer Enables High-Performance Solid-State Sodium Batteries with Sulfide Solid Electrolyte

All-solid-state sodium (Na) batteries (ASSSBs) using sulfide-based solid electrolytes (SEs) have attracted intensive attention due to their superior safety, high energy density and low cost. However, interfacial issue is one of the biggest challenges to achieve high-performance sulfide-based ASSSBs due to the serious reactions between active Na metal and sulfide SEs at the interface. To address the interfacial challenges, we propose in this paper a simple and efficient approach by introducing a polymer electrolyte as an interlayer to stabilize the interface. Na 3 SbS 4 as a model sulfide SE is used to demonstrate the interlayer strategy to stabilize the interface by preventing the detrimental reactions and inhibiting Na dendrites. As a result, stable Na plating/stripping was observed in Na symmetric cells under the current density of 0.1 mA cm –2 . Moreover, ASSSBs with Na metal and TiS 2 electrode delivered long-term stability over 300 cycles remaining a specific capacity above 100 mAh g –1 , and FeS 2 ||Na cells exhibited an impressive specific capacity of up to 200 mAh g –1 after the 20th cycles. This work demonstrates an efficient strategy to address interfacial challenges between sulfide SEs and Na metal, which contributes to the development of ASSSBs in next-generation energy storage systems.

25 ENERGY STORAGE↗

DOE OSTI2020

Materials Data on Na2O2 by Materials Project

Na2O2 is alpha boron-derived structured and crystallizes in the hexagonal P-62m space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are four shorter (2.34 Å) and two longer (2.40 Å) Na–O bond lengths. In the second Na site, Na is bonded in a 6-coordinate geometry to six O atoms. There are two shorter (2.42 Å) and four longer (2.49 Å) Na–O bond lengths. There are two inequivalent O sites. In the first O site, O is bonded in a 7-coordinate geometry to six Na and one O atom. The O–O bond length is 1.54 Å. In the second O site, O is bonded to six Na and one O atom to form a mixture of distorted corner, edge, and face-sharing ONa6O pentagonal bipyramids. The O–O bond length is 1.55 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on NaS2 by Materials Project

NaSS crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 4-coordinate geometry to six S atoms. There are a spread of Na–S bond distances ranging from 2.85–3.27 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six S atoms. There are a spread of Na–S bond distances ranging from 2.91–3.11 Å. There are two inequivalent S sites. In the first S site, S is bonded in a 5-coordinate geometry to four Na and one S atom. The S–S bond length is 2.09 Å. In the second S site, S is bonded in a 4-coordinate geometry to two Na and two S atoms. The S–S bond length is 2.07 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on NaSe2 by Materials Project

NaSe2 crystallizes in the tetragonal I-42d space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to six Se atoms to form distorted corner-sharing NaSe6 pentagonal pyramids. There are a spread of Na–Se bond distances ranging from 2.96–3.24 Å. In the second Na site, Na is bonded in a 6-coordinate geometry to six Se atoms. There are a spread of Na–Se bond distances ranging from 2.97–3.27 Å. There are two inequivalent Se sites. In the first Se site, Se is bonded in a distorted see-saw-like geometry to two Na and two Se atoms. There are one shorter (2.39 Å) and one longer (2.41 Å) Se–Se bond lengths. In the second Se site, Se is bonded in a 5-coordinate geometry to four Na and one Se atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Ba3NaSi23 by Materials Project

NaBa3Si23 crystallizes in the cubic Pm-3n space group. The structure is three-dimensional. Na is bonded in a 8-coordinate geometry to twenty Si atoms. There are eight shorter (3.29 Å) and twelve longer (3.38 Å) Na–Si bond lengths. There are two inequivalent Ba sites. In the first Ba site, Ba is bonded in a 12-coordinate geometry to twenty Si atoms. There are a spread of Ba–Si bond distances ranging from 3.51–3.84 Å. In the second Ba site, Ba is bonded in a 12-coordinate geometry to twenty Si atoms. There are a spread of Ba–Si bond distances ranging from 3.51–3.84 Å. There are ten inequivalent Si sites. In the first Si site, Si is bonded in a 8-coordinate geometry to one Na, three Ba, and four Si atoms. The Si–Ba bond length is 3.84 Å. All Si–Si bond lengths are 2.36 Å. In the second Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Ba, and four Si atoms. There are one shorter (2.42 Å) and one longer (2.49 Å) Si–Si bond lengths. In the third Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Ba, and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.36–2.49 Å. In the fourth Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Ba, and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.36–2.49 Å. In the fifth Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Ba, and four Si atoms. There are a spread of Si–Si bond distances ranging from 2.36–2.49 Å. In the sixth Si site, Si is bonded in a 7-coordinate geometry to one Na, two equivalent Ba, and four Si atoms. The Si–Si bond length is 2.42 Å. In the seventh Si site, Si is bonded to four Ba and four Si atoms to form a mixture of distorted edge and corner-sharing SiBa4Si4 tetrahedra. In the eighth Si site, Si is bonded to four equivalent Ba and four equivalent Si atoms to form distorted corner-sharing SiBa4Si4 tetrahedra. In the ninth Si site, Si is bonded in a distorted body-centered cubic geometry to four equivalent Ba and four equivalent Si atoms. In the tenth Si site, Si is bonded in a 8-coordinate geometry to one Na, three Ba, and four Si atoms. The Si–Si bond length is 2.36 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Na2FeO4 by Materials Project

Na2FeO4 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to six O atoms to form NaO6 octahedra that share corners with six equivalent FeO4 tetrahedra and edges with two equivalent NaO6 octahedra. There are two shorter (2.38 Å) and four longer (2.44 Å) Na–O bond lengths. In the second Na site, Na is bonded in a 4-coordinate geometry to four O atoms. There are two shorter (2.36 Å) and two longer (2.49 Å) Na–O bond lengths. Fe is bonded to four O atoms to form FeO4 tetrahedra that share corners with six equivalent NaO6 octahedra. The corner-sharing octahedra tilt angles range from 43–51°. There is two shorter (1.65 Å) and two longer (1.67 Å) Fe–O bond length. There are two inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two Na and one Fe atom. In the second O site, O is bonded in a 4-coordinate geometry to three Na and one Fe atom.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Na2CdPb by Materials Project

Na2CdPb crystallizes in the cubic F-43m space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded to four equivalent Pb atoms to form distorted corner-sharing NaPb4 tetrahedra. All Na–Pb bond lengths are 3.25 Å. In the second Na site, Na is bonded to four equivalent Cd atoms to form distorted corner-sharing NaCd4 tetrahedra. All Na–Cd bond lengths are 3.25 Å. Cd is bonded in a body-centered cubic geometry to four equivalent Na and four equivalent Pb atoms. All Cd–Pb bond lengths are 3.25 Å. Pb is bonded in a distorted body-centered cubic geometry to four equivalent Na and four equivalent Cd atoms.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on NaSi by Materials Project

NaSi crystallizes in the monoclinic C2/c space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 3-coordinate geometry to six Si atoms. There are a spread of Na–Si bond distances ranging from 3.01–3.40 Å. In the second Na site, Na is bonded in a 4-coordinate geometry to five Si atoms. There are a spread of Na–Si bond distances ranging from 2.88–3.31 Å. There are two inequivalent Si sites. In the first Si site, Si is bonded in a 9-coordinate geometry to six Na and three Si atoms. There are a spread of Si–Si bond distances ranging from 2.40–2.48 Å. In the second Si site, Si is bonded in a 8-coordinate geometry to five Na and three Si atoms. The Si–Si bond length is 2.42 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Na8Ti5O14 by Materials Project

Na8Ti5O14 is Krennerite-derived structured and crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are nine inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two NaO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 21–23°. There are a spread of Na–O bond distances ranging from 2.28–2.59 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two NaO6 octahedra, corners with two equivalent TiO6 octahedra, an edgeedge with one TiO6 octahedra, and edges with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 14–25°. There are a spread of Na–O bond distances ranging from 2.37–2.63 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with two equivalent NaO6 octahedra, edges with two TiO6 octahedra, and edges with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 14–18°. There are a spread of Na–O bond distances ranging from 2.29–2.61 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share a cornercorner with one NaO6 octahedra, a cornercorner with one TiO6 octahedra, edges with three TiO6 octahedra, and edges with six NaO6 octahedra. The corner-sharing octahedra tilt angles range from 22–26°. There are a spread of Na–O bond distances ranging from 2.32–2.64 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two TiO6 octahedra, corners with four NaO6 octahedra, edges with two TiO6 octahedra, and edges with five NaO6 octahedra. The corner-sharing octahedra tilt angles range from 14–26°. There are a spread of Na–O bond distances ranging from 2.32–2.46 Å. In the sixth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with two NaO6 octahedra, corners with three TiO6 octahedra, edges with two TiO6 octahedra, and edges with seven NaO6 octahedra. The corner-sharing octahedra tilt angles range from 1–23°. There are a spread of Na–O bond distances ranging from 2.37–2.53 Å. In the seventh Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.33–2.90 Å. In the eighth Na1+ site, Na1+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Na–O bond distances ranging from 2.31–2.47 Å. In the ninth Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with two equivalent NaO6 octahedra, corners with two equivalent TiO6 octahedra, edges with two equivalent TiO6 octahedra, and edges with eight NaO6 octahedra. The corner-sharing octahedral tilt angles are 14°. There are a spread of Na–O bond distances ranging from 2.33–2.47 Å. There are five inequivalent Ti4+ sites. In the first Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share corners with three NaO6 octahedra, edges with three TiO6 octahedra, and edges with five NaO6 octahedra. The corner-sharing octahedra tilt angles range from 1–26°. There are a spread of Ti–O bond distances ranging from 1.81–2.30 Å. In the second Ti4+ site, Ti4+ is bonded to six O2- atoms to form TiO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with three NaO6 octahedra, edges with four NaO6 octahedra, and edges with four TiO6 octahedra. The corner-sharing octahedra tilt angles range from 6–22°. There are a spread of Ti–O bond distances ranging from 1.84–2.17 Å. In the third Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.80–2.34 Å. In the fourth Ti4+ site, Ti4+ is bonded in a 6-coordinate geometry to six O2- atoms. There are a spread of Ti–O bond distances ranging from 1.77–2.39 Å. In the fifth Ti4+ site, Ti4+ is bonded to six O2- atoms to form distorted TiO6 octahedra that share a cornercorner with one TiO6 octahedra, corners with four NaO6 octahedra, edges with two TiO6 octahedra, and edges with four NaO6 octahedra. The corner-sharing octahedra tilt angles range from 6–26°. There are a spread of Ti–O bond distances ranging from 1.75–2.35 Å. There are fourteen inequivalent O2- sites. In the first O2- site, O2- is bonded to three Na1+ and two Ti4+ atoms to form distorted ONa3Ti2 trigonal bipyramids that share a cornercorner with one ONa5Ti octahedra, corners with three ONa2Ti3 square pyramids, a cornercorner with one ONa3Ti2 trigonal bipyramid, and edges with two OTi6 octahedra. The corner-sharing octahedral tilt angles are 50°. In the second O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+ and two Ti4+ atoms. In the third O2- site, O2- is bonded to five Na1+ and one Ti4+ atom to form distorted ONa5Ti octahedra that share corners with two OTi6 octahedra, corners with two ONa2Ti3 square pyramids, edges with two equivalent ONa5Ti octahedra, edges with two ONa2Ti3 square pyramids, and an edgeedge with one ONa3Ti2 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 0–3°. In the fourth O2- site, O2- is bonded to two equivalent Na1+ and three Ti4+ atoms to form distorted ONa2Ti3 square pyramids that share corners with two ONa5Ti octahedra, a cornercorner with one ONa3Ti2 trigonal bipyramid, edges with four OTi6 octahedra, and an edgeedge with one ONa2Ti3 square pyramid. The corner-sharing octahedra tilt angles range from 8–78°. In the fifth O2- site, O2- is bonded in a 6-coordinate geometry to three Na1+ and three Ti4+ atoms. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two Ti4+ atoms. In the seventh O2- site, O2- is bonded to six Ti4+ atoms to form OTi6 octahedra that share corners with two ONa5Ti octahedra, a cornercorner with one ONa4Ti square pyramid, an edgeedge with one OTi6 octahedra, edges with two equivalent ONa2Ti3 square pyramids, and an edgeedge with one ONa3Ti2 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 3–6°. In the eighth O2- site, O2- is bonded in a 5-coordinate geometry to three Na1+ and two Ti4+ atoms. In the ninth O2- site, O2- is bonded in a 5-coordinate geometry to four Na1+ and two Ti4+ atoms. In the tenth O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two Ti4+ atoms. In the eleventh O2- site, O2- is bonded to four Na1+ and one Ti4+ atom to form distorted ONa4Ti square pyramids that share corners with two OTi6 octahedra, corners with two equivalent ONa3Ti2 trigonal bipyramids, an edgeedge with one ONa5Ti octahedra, and an edgeedge with one ONa4Ti square pyramid. The corner-sharing octahedra tilt angles range from 6–14°. In the twelfth O2- site, O2- is bonded in a 6-coordinate geometry to four Na1+ and two Ti4+ atoms. In the thirteenth O2- site, O2- is bonded in a 4-coordinate geometry to four Na1+ and one Ti4+ atom. In the fourteenth O2- site, O2- is bonded to five Na1+ and one Ti4+ atom to form distorted ONa5Ti octahedra that share corners with two OTi6 octahedra, a cornercorner with one ONa2Ti3 square pyramid, a cornercorner with one ONa3Ti2 trigonal bipyramid, edges with two equivalent ONa5Ti octahedra, and an edgeedge with one ONa2Ti3 square pyramid. The corner-sharing octahedra tilt angles range from 0–6°.

36 MATERIALS SCIENCE↗

DOE OSTI2020

Materials Data on Na4SeO5 by Materials Project

Na4SeO5 crystallizes in the triclinic P-1 space group. The structure is three-dimensional. there are nine inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, corners with two equivalent SeO5 trigonal bipyramids, edges with nine NaO6 octahedra, an edgeedge with one SeO5 square pyramid, and an edgeedge with one SeO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 12–33°. There are a spread of Na–O bond distances ranging from 2.34–2.80 Å. In the second Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, a cornercorner with one SeO5 square pyramid, a cornercorner with one SeO5 trigonal bipyramid, edges with nine NaO6 octahedra, and edges with two equivalent SeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 11–36°. There are a spread of Na–O bond distances ranging from 2.40–2.78 Å. In the third Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four NaO6 octahedra, corners with two equivalent SeO5 square pyramids, edges with ten NaO6 octahedra, and edges with two equivalent SeO5 square pyramids. The corner-sharing octahedra tilt angles range from 12–21°. There are a spread of Na–O bond distances ranging from 2.32–2.93 Å. In the fourth Na1+ site, Na1+ is bonded to six O2- atoms to form NaO6 octahedra that share corners with four NaO6 octahedra, corners with four equivalent SeO5 square pyramids, corners with two equivalent SeO5 trigonal bipyramids, and edges with eight NaO6 octahedra. The corner-sharing octahedra tilt angles range from 33–36°. There are a spread of Na–O bond distances ranging from 2.40–2.77 Å. In the fifth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, edges with nine NaO6 octahedra, edges with two equivalent SeO5 square pyramids, and an edgeedge with one SeO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 10–28°. There are a spread of Na–O bond distances ranging from 2.34–2.46 Å. In the sixth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with six NaO6 octahedra, a cornercorner with one SeO5 square pyramid, a cornercorner with one SeO5 trigonal bipyramid, edges with eight NaO6 octahedra, an edgeedge with one SeO5 square pyramid, and an edgeedge with one SeO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 24–35°. There are a spread of Na–O bond distances ranging from 2.32–2.56 Å. In the seventh Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, corners with two equivalent SeO5 trigonal bipyramids, edges with nine NaO6 octahedra, and edges with two equivalent SeO5 square pyramids. The corner-sharing octahedra tilt angles range from 10–34°. There are a spread of Na–O bond distances ranging from 2.29–2.91 Å. In the eighth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with four NaO6 octahedra, corners with two equivalent SeO5 square pyramids, edges with ten NaO6 octahedra, and edges with two equivalent SeO5 trigonal bipyramids. The corner-sharing octahedra tilt angles range from 15–27°. There are a spread of Na–O bond distances ranging from 2.29–2.85 Å. In the ninth Na1+ site, Na1+ is bonded to six O2- atoms to form distorted NaO6 octahedra that share corners with five NaO6 octahedra, a cornercorner with one SeO5 square pyramid, a cornercorner with one SeO5 trigonal bipyramid, edges with nine NaO6 octahedra, an edgeedge with one SeO5 square pyramid, and an edgeedge with one SeO5 trigonal bipyramid. The corner-sharing octahedra tilt angles range from 21–35°. There are a spread of Na–O bond distances ranging from 2.33–2.64 Å. There are two inequivalent Se6+ sites. In the first Se6+ site, Se6+ is bonded to five O2- atoms to form SeO5 trigonal bipyramids that share corners with eight NaO6 octahedra and edges with eight NaO6 octahedra. The corner-sharing octahedra tilt angles range from 3–72°. There are a spread of Se–O bond distances ranging from 1.74–1.82 Å. In the second Se6+ site, Se6+ is bonded to five O2- atoms to form SeO5 square pyramids that share corners with eight NaO6 octahedra and edges with eight NaO6 octahedra. The corner-sharing octahedra tilt angles range from 2–72°. There are a spread of Se–O bond distances ranging from 1.75–1.83 Å. There are ten inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Se6+ atom. In the second O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Se6+ atom. In the third O2- site, O2- is bonded to five Na1+ and one Se6+ atom to form ONa5Se octahedra that share a cornercorner with one ONa5Se octahedra, a cornercorner with one ONa4Se trigonal bipyramid, an edgeedge with one ONa5Se octahedra, and an edgeedge with one ONa4Se trigonal bipyramid. The corner-sharing octahedral tilt angles are 0°. In the fourth O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Se6+ atom. In the fifth O2- site, O2- is bonded to four Na1+ and one Se6+ atom to form distorted ONa4Se trigonal bipyramids that share corners with four ONa4Se trigonal bipyramids and edges with two equivalent ONa5Se octahedra. In the sixth O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Se6+ atom. In the seventh O2- site, O2- is bonded to five Na1+ and one Se6+ atom to form distorted ONa5Se octahedra that share edges with two ONa5Se octahedra and edges with two equivalent ONa4Se trigonal bipyramids. In the eighth O2- site, O2- is bonded to four Na1+ and one Se6+ atom to form distorted ONa4Se trigonal bipyramids that share a cornercorner with one ONa5Se octahedra, corners with four ONa4Se trigonal bipyramids, and an edgeedge with one ONa5Se octahedra. The corner-sharing octahedral tilt angles are 19°. In the ninth O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Se6+ atom. In the tenth O2- site, O2- is bonded in a 6-coordinate geometry to five Na1+ and one Se6+ atom.

36 MATERIALS SCIENCE↗