NaCoO2
Sodium cobaltite · Sodium cobalt oxide
NaCoO2 is a stable, layered semiconducting oxide used primarily as a model material in the development of sodium-ion battery technologies.
About Sodium cobaltite
NaCoO2 is a prominent member of the layered sodium transition-metal oxide family, characterized by its stable structural configuration on the convex hull. As a semiconducting oxide, it serves as a fundamental building block for understanding ion transport and electronic behavior in energy storage systems. Its layered arrangement allows for the reversible intercalation of sodium ions, making it a subject of intense investigation for next-generation battery cathodes. The material is highly regarded for its structural integrity and its role in advancing the performance of sodium-based electrochemical devices.
Key Properties
Cross-validated computational properties for Sodium cobaltite, aggregated across 3 databases.
Band GapEnergy needed to move an electron from the valence band to the conduction band. Lower or zero values tend to behave more metallic; larger gaps are more insulating or semiconducting.
Energy Above HullThermodynamic distance from the most stable set of competing phases. 0 eV/atom is on the convex hull; small positive values may still be experimentally accessible.
StabilityA plain-language summary of the best reported energy-above-hull result. It reflects whether the lowest-energy structure is on, near, or far from the stability hull.
StructuresCount of reported calculated crystal structures for this formula, including alternate polymorphs, source databases, and observed space groups.
Cross-Source DFT Agreement
How well independent DFT databases agree on the thermodynamics of NaCoO2. Tight agreement means computed properties can be trusted without re-running calculations.
Agreement ScoreA normalized confidence score summarizing how closely independent DFT databases agree. Higher scores mean tighter cross-source agreement.
Hull SpreadDifference between the highest and lowest energy-above-hull values reported by comparable sources. Smaller spread means less thermodynamic disagreement.
Sources ComparedNumber and names of computational sources with comparable entries for this formula.
Space Group ConsensusWhether independent sources predict the same crystal symmetry for the lowest-energy structure.
Reported Structures
Lowest-energy structures reported for NaCoO2, ranked by energy above hull.
| Space GroupSymmetry classification of the crystal arrangement. The number is the international space-group index. | Crystal SystemBroad lattice family, such as cubic, tetragonal, monoclinic, or triclinic, derived from unit-cell symmetry. | Band Gap (eV)Electronic gap calculated for this specific reported structure, measured in electronvolts. | E above hull (eV/atom)Thermodynamic distance from the convex hull for this structure, normalized per atom. Lower is generally more stable. | E/atom (eV)Computed total energy normalized per atom. Use energy above hull, not this value alone, when comparing stability. | Density (g/cm³)Mass per relaxed crystal volume, reported in grams per cubic centimeter. |
|---|---|---|---|---|---|
| R-3m (No. 166) | trigonal | 2.16 | 0.0000 | -6.150 | 5.11 |
| — | — | 1.98 | 0.0000 | -1.487 | — |
| R-3m (No. 166) | trigonal | 0.88 | 0.0000 | -1.507 | — |
| R-3m (No. 166) | trigonal | 0.88 | 0.0006 | -1.507 | — |
| R-3m (No. 166) | trigonal | 0.88 | 0.0006 | -1.507 | — |
| — | — | 1.42 | 0.0056 | -1.481 | — |
| P63/mmc (No. 194) | hexagonal | 2.12 | 0.0139 | -6.136 | 5.08 |
| P63/mmc (No. 194) | hexagonal | 0.84 | 0.0144 | -1.493 | — |
| R3m (No. 160) | trigonal | 0.89 | 0.0236 | -1.484 | — |
| — | — | 0.92 | 0.0302 | -1.456 | — |
| — | — | 1.00 | 0.0354 | -1.451 | — |
| P-3m1 (No. 164) | trigonal | 0.96 | 0.0530 | -1.454 | — |
Synthesis Routes
Literature-extracted synthesis procedures targeting NaCoO2.
Applications
Where Sodium cobaltite is used.
Frequently Asked Questions
Common questions about Sodium cobaltite, answered from cross-validated data.
What is NaCoO2?
NaCoO2 is a stable, layered semiconducting oxide used primarily as a model material in the development of sodium-ion battery technologies.
What is NaCoO2 used for?
What is the band gap of NaCoO2?
Is NaCoO2 a metal, semiconductor, or insulator?
Is NaCoO2 thermodynamically stable?
What is the crystal structure of NaCoO2?
What is the density of NaCoO2?
How many polymorphs of NaCoO2 are known?
How is NaCoO2 synthesized?
What elements does NaCoO2 contain?
Where does the data for NaCoO2 come from?
How It Compares
Within the layered sodium transition-metal oxides class.
Within the diverse family of layered sodium transition-metal oxides, NaCoO2 stands out for its robust thermodynamic stability compared to more complex or less ordered counterparts like Na2Ti3O7 or Na2CoO3. While materials such as NaFeO2 or NaMnO2 are frequently explored for their earth-abundant potential, NaCoO2 remains a benchmark for structural reliability and electrochemical performance in the development of sodium-ion cathode chemistries.
Related Compounds
Other Layered Sodium Transition-Metal Oxides in the database.
Data sources & attribution
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- oqmd — Data from the OQMD (oqmd.org). Cite: Saal et al., JOM 65, 1501 (2013); Kirklin et al., npj Comp. Mater. 1, 15010 (2015). (CC-BY-4.0)
- jarvis — Data from JARVIS (jarvis.nist.gov), NIST. Cite: Choudhary et al., npj Comp. Mater. 6, 173 (2020). (LicenseRef-US-Gov-PD)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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