Li4P2O7
lithium pyrophosphate · tetralithium pyrophosphate
Lithium pyrophosphate is a stable, insulating lithium oxide compound frequently researched for its potential applications in solid-state battery electrolytes.
About lithium pyrophosphate
Lithium pyrophosphate is a thermodynamically stable member of the lithium oxide family, characterized by its wide-band-gap insulating electronic structure. Its structural integrity and chemical stability make it a subject of significant interest for researchers exploring solid-state ion transport.
As a phosphate-based lithium compound, it serves as a foundational material in the study of ionic conductors. Its role is particularly vital in the development of next-generation energy storage systems where insulating, chemically robust frameworks are required to facilitate stable lithium-ion movement.
Key Properties
Cross-validated computational properties for lithium pyrophosphate, 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 Li4P2O7. 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 Li4P2O7, 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. |
|---|---|---|---|---|---|
| — | — | 6.04 | 0.0000 | -2.634 | — |
| P-1 (No. 2) | triclinic | 5.98 | 0.0000 | -2.500 | — |
| P-1 (No. 2) | triclinic | 5.61 | 0.0000 | -6.828 | 2.38 |
| P21/c (No. 14) | monoclinic | 5.65 | 0.0001 | -6.828 | 2.26 |
| — | — | 6.25 | 0.0005 | -2.634 | — |
| — | — | 5.83 | 0.0176 | -2.617 | — |
| P21/c (No. 14) | monoclinic | 5.58 | 0.0181 | -6.810 | 2.28 |
| P-1 (No. 2) | triclinic | 2.91 | 0.4898 | -2.010 | — |
| P-1 (No. 2) | triclinic | 2.85 | 0.5427 | -6.286 | 2.31 |
| P-1 (No. 2) | triclinic | — | — | — | 2.35 |
| P-1 (No. 2) | triclinic | — | — | — | 2.29 |
| P21/c (No. 14) | monoclinic | — | — | — | 2.35 |
Synthesis Routes
Literature-extracted synthesis procedures targeting Li4P2O7.
Applications
Where lithium pyrophosphate is used.
Frequently Asked Questions
Common questions about lithium pyrophosphate, answered from cross-validated data.
What is Li4P2O7?
Lithium pyrophosphate is a stable, insulating lithium oxide compound frequently researched for its potential applications in solid-state battery electrolytes.
What is Li4P2O7 used for?
What is the band gap of Li4P2O7?
Is Li4P2O7 a metal, semiconductor, or insulator?
Is Li4P2O7 thermodynamically stable?
What is the crystal structure of Li4P2O7?
How many polymorphs of Li4P2O7 are known?
How is Li4P2O7 synthesized?
What elements does Li4P2O7 contain?
Where does the data for Li4P2O7 come from?
How It Compares
Within the lithium oxides class.
Unlike the transition-metal-heavy lithium oxides such as LiCoO2, LiNiO2, or LiMn2O4, which are primarily utilized for their redox-active metal centers in cathode applications, Li4P2O7 functions as a wide-gap insulator. It shares more structural and electronic commonalities with stable, non-redox-active oxides like Li4SiO4, positioning it as a specialized candidate for electrolyte or separator research rather than as an active cathode material.
Related Compounds
Other Lithium Oxides in the database.
Data sources & attribution
- 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)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (CC-BY-4.0)
- cod — Data from the Crystallography Open Database (crystallography.net/cod/). Cite: Grazulis et al., J. Appl. Cryst. 42, 726 (2009). (CC0-1.0)
- mpaloe — Data from MP-ALOE. Cite: Kuner et al., npj Comput. Mater. (2025), doi:10.1038/s41524-025-01834-9.
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