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17 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

Whole-Voltage-Range Oxygen Redox in P2-Layered Cathode Materials for Sodium-Ion Batteries

Oxygen-redox of layer-structured metal-oxide cathodes has drawn great attention as an effective approach to break through the bottleneck of their capacity limit. However, reversible oxygen-redox can only be obtained in the high-voltage region (usually over 3.5 V) in current metal-oxide cathodes. Here, we realize reversible oxygen-redox in a wide voltage range of 1.5-4.5 V in a P2-layered Na 0.7 Mg 0.2 [Fe 0.2 Mn 0.6 $\square$0.2]O 2 cathode material, where intrinsic vacancies are located in transition-metal (TM) sites and Mg-ions are located in Na sites. Mg-ions in the Na layer serve as "pillars" to stabilize the layered structure during electrochemical cycling, especially in the high-voltage region. Intrinsic vacancies in the TM layer create the local configurations of "$\square$-O-$\square$", "Na-O-$\square$" and "Mg-O-$\square$" to trigger oxygen-redox in the whole voltage range of charge-discharge. Additionally, time-resolved techniques demonstrate that the P2 phase is well maintained in a wide potential window range of 1.5-4.5 V even at 10 C. It is revealed that charge compensation from Mn- and O-ions contributes to the whole voltage range of 1.5-4.5 V, while the redox of Fe-ions only contributes to the high-voltage region of 3.0-4.5 V. The orphaned electrons in the nonbonding 2p orbitals of O that point toward TM-vacancy sites are responsible for reversible oxygen-redox, and Mg-ions in Na sites suppress oxygen release effectively.

25 ENERGY STORAGE↗
DOE OSTI2026

Chemical factors controlling the behaviour of oxide cathodes in batteries

Oxide cathodes enable high-energy lithium-ion and sodium-ion batteries, with their performances fundamentally governed by three interrelated chemical factors: electronic configuration, chemical bonding, and chemical reactivity. Here, we illustrate how these factors dictate the redox energy, structural stability, ionic and electronic transport, and interfacial behavior in both layered oxide and polyanion oxide cathodes. We discuss how crystal-field effects and octahedral-site stabilization energies influence cation migration, and how inductive effects tune bond covalency and operating voltages. We also explain how chemical bonding governs thermal stability, gas evolution, and first-cycle capacity loss, and how alignment of transition-metal redox band with the oxygen 2p band determines electrolyte reactivity. Comparison between lithium and sodium layered oxides further reveals how differences in Li-O and Na-O bond ionicity affect chemical reactivity. Finally, we outline strategies including compositional tuning, surface doping, and electrolyte optimization, and emphasize how high-throughput, data-driven approaches in guiding the design of next-generation oxide cathodes.

25 ENERGY STORAGE↗
DOE OSTI2024

Sustainable layered cathode with suppressed phase transition for long-life sodium-ion batteries

Sodium-ion batteries are among the most promising alternatives to lithium-based technologies for grid and other energy storage applications due to their cost benefits and sustainable resource supply. For the cathode—the component that largely determines the energy density of a sodium-ion battery cell—one major category of materials is P2-type layered oxides. Unfortunately, at high state-of-charge, such materials tend to undergo a phase transition with a very large volume change and consequent structural degradation during long-term cycling. Here we address this issue by introducing vacancies into the transition metal layer of P2-Na$_{0.7}$Fe$_{0.1}$Mn$_{0.75\square}$$_{0.15}$O2 (‘$_{\square}$’ represents a vacancy). The transition metal vacancy serves to suppress migration of neighbouring Na ions and therefore maintain structural and thermal stability in Na-depleted states. Moreover, the specific Na-O-$_{\square}$ configuration triggers a reversible anionic redox reaction and boosts the energy density. As a result, the cathode design here enables pouch cells with energy densities of 170 Wh kg -1 and 120 Wh kg -1 that can operate for over 600 and 1,000 cycles, respectively. In conclusion, our work not only suggests a feasible strategy for cathode design but also confirms the possibility of developing a battery chemistry that features a reduced need for critical raw materials.

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 NaO2 by Materials Project

NaO2 is Marcasite structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Na is bonded to six equivalent O atoms to form NaO6 octahedra that share corners with eight equivalent NaO6 octahedra, corners with six equivalent ONa3O tetrahedra, and edges with two equivalent NaO6 octahedra. The corner-sharing octahedral tilt angles are 71°. All Na–O bond lengths are 2.42 Å. O is bonded to three equivalent Na and one O atom to form distorted ONa3O tetrahedra that share corners with three equivalent NaO6 octahedra, corners with thirteen equivalent ONa3O tetrahedra, and an edgeedge with one ONa3O tetrahedra. The corner-sharing octahedra tilt angles range from 58–69°. The O–O bond length is 1.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaO3 by Materials Project

NaO3 is Baddeleyite-like structured and crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. Na is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Na–O bond distances ranging from 2.47–2.71 Å. There are two inequivalent O sites. In the first O site, O is bonded to three equivalent Na and one O atom to form a mixture of distorted edge and corner-sharing ONa3O tetrahedra. The O–O bond length is 1.37 Å. In the second O site, O is bonded in a trigonal planar geometry to one Na and two equivalent O atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O is Fluorite structured and crystallizes in the cubic Fm-3m space group. The structure is three-dimensional. Na1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing NaO4 tetrahedra. All Na–O bond lengths are 2.42 Å. O2- is bonded in a body-centered cubic geometry to eight equivalent Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O is Cotunnite-like structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Na2O sheet oriented in the (0, 0, 1) direction. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a trigonal non-coplanar geometry to three equivalent O2- atoms. All Na–O bond lengths are 2.37 Å. In the second Na1+ site, Na1+ is bonded to four equivalent O2- atoms to form a mixture of edge and corner-sharing NaO4 tetrahedra. There are three shorter (2.35 Å) and one longer (2.48 Å) Na–O bond lengths. O2- is bonded in a 7-coordinate geometry to seven Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaO2 by Materials Project

NaO2 crystallizes in the cubic Pa-3 space group. The structure is three-dimensional. Na is bonded to six equivalent O atoms to form NaO6 octahedra that share corners with twelve equivalent NaO6 octahedra and corners with six equivalent ONa3O tetrahedra. The corner-sharing octahedral tilt angles are 73°. All Na–O bond lengths are 2.43 Å. O is bonded to three equivalent Na and one O atom to form ONa3O tetrahedra that share corners with three equivalent NaO6 octahedra and corners with fifteen equivalent ONa3O tetrahedra. The corner-sharing octahedral tilt angles are 68°. The O–O bond length is 1.35 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O is Hydrophilite-like structured and crystallizes in the orthorhombic Pnnm space group. The structure is three-dimensional. Na1+ is bonded in a trigonal planar geometry to three equivalent O2- atoms. There are one shorter (2.31 Å) and two longer (2.33 Å) Na–O bond lengths. O2- is bonded to six equivalent Na1+ atoms to form a mixture of edge and corner-sharing ONa6 octahedra. The corner-sharing octahedral tilt angles are 53°.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O crystallizes in the trigonal P3 space group. The structure is three-dimensional. there are two inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded in a 4-coordinate geometry to five O2- atoms. There are a spread of Na–O bond distances ranging from 2.43–2.96 Å. In the second Na1+ site, Na1+ is bonded to four O2- atoms to form a mixture of distorted edge and corner-sharing NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.30–2.49 Å. There are three inequivalent O2- sites. In the first O2- site, O2- is bonded in a 6-coordinate geometry to nine Na1+ atoms. In the second O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms. In the third O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O by Materials Project

Na2O crystallizes in the trigonal P321 space group. The structure is three-dimensional. there are three inequivalent Na1+ sites. In the first Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with ten equivalent NaO5 square pyramids, corners with six equivalent NaO4 tetrahedra, edges with six NaO5 square pyramids, and edges with six equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.55–2.62 Å. In the second Na1+ site, Na1+ is bonded to four O2- atoms to form distorted NaO4 tetrahedra that share corners with six NaO5 square pyramids, corners with ten equivalent NaO4 tetrahedra, edges with six NaO5 square pyramids, and edges with two equivalent NaO4 tetrahedra. There are two shorter (2.32 Å) and two longer (2.44 Å) Na–O bond lengths. In the third Na1+ site, Na1+ is bonded to five O2- atoms to form distorted NaO5 square pyramids that share corners with ten NaO5 square pyramids, corners with six equivalent NaO4 tetrahedra, edges with six NaO5 square pyramids, and edges with six equivalent NaO4 tetrahedra. There are a spread of Na–O bond distances ranging from 2.55–2.62 Å. There are two inequivalent O2- sites. In the first O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms. In the second O2- site, O2- is bonded in a 9-coordinate geometry to nine Na1+ atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaO5 by Materials Project

NaO5 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one NaO5 sheet oriented in the (2, 0, -1) direction. Na is bonded in a 7-coordinate geometry to nine O atoms. There are a spread of Na–O bond distances ranging from 2.32–2.89 Å. There are five inequivalent O sites. In the first O site, O is bonded in a 2-coordinate geometry to two equivalent Na and two equivalent O atoms. Both O–O bond lengths are 1.63 Å. In the second O site, O is bonded in a pentagonal planar geometry to three equivalent Na and two equivalent O atoms. Both O–O bond lengths are 1.64 Å. In the third O site, O is bonded to two equivalent Na and two equivalent O atoms to form a mixture of distorted edge and corner-sharing ONa2O2 trigonal pyramids. In the fourth O site, O is bonded in a 4-coordinate geometry to two equivalent Na and one O atom. The O–O bond length is 1.24 Å. In the fifth O site, O is bonded in a single-bond geometry to one O atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on NaO2 by Materials Project

Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O2 by Materials Project

Na2O2 is Tungsten Carbide-like structured and crystallizes in the orthorhombic Pbcm space group. The structure is three-dimensional. Na is bonded to six equivalent O atoms to form a mixture of distorted edge, corner, and face-sharing NaO6 octahedra. The corner-sharing octahedra tilt angles range from 31–52°. There are a spread of Na–O bond distances ranging from 2.40–2.43 Å. O is bonded to six equivalent Na atoms to form a mixture of distorted edge and corner-sharing ONa6 pentagonal pyramids.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Na2O9 by Materials Project

Na2O9 crystallizes in the monoclinic P2_1/c space group. The structure is three-dimensional. there are two inequivalent Na sites. In the first Na site, Na is bonded in a 8-coordinate geometry to nine O atoms. There are a spread of Na–O bond distances ranging from 2.34–2.91 Å. In the second Na site, Na is bonded in a 7-coordinate geometry to seven O atoms. There are a spread of Na–O bond distances ranging from 2.39–2.89 Å. There are nine inequivalent O sites. In the first O site, O is bonded in a 3-coordinate geometry to two Na and one O atom. The O–O bond length is 1.31 Å. In the second O site, O is bonded in a single-bond geometry to one O atom. The O–O bond length is 1.25 Å. In the third O site, O is bonded in a 4-coordinate geometry to three Na and one O atom. The O–O bond length is 1.30 Å. In the fourth O site, O is bonded in a 2-coordinate geometry to two Na and two O atoms. There is one shorter (1.28 Å) and one longer (1.99 Å) O–O bond length. In the fifth O site, O is bonded in a 1-coordinate geometry to two Na and two O atoms. In the sixth O site, O is bonded in a 3-coordinate geometry to two Na and one O atom. In the seventh O site, O is bonded in a 3-coordinate geometry to two equivalent Na and one O atom. In the eighth O site, O is bonded in a bent 120 degrees geometry to one Na and one O atom. The O–O bond length is 1.29 Å. In the ninth O site, O is bonded in a 3-coordinate geometry to two Na and one O atom.

36 MATERIALS SCIENCE↗