KSi
KSi is a stable, semiconducting binary compound of potassium and silicon used primarily in the study of advanced battery anode materials.
About KSi
KSi is a semiconducting intermetallic compound that occupies a distinct position within the landscape of silicon-based anode materials. As a thermodynamically stable phase located on the convex hull, it represents a well-defined structural arrangement of potassium and silicon atoms that is highly relevant for fundamental materials research.
This compound is of significant interest to researchers investigating the structural evolution of silicon anodes during electrochemical cycling. Its stability and well-characterized nature make it a valuable reference point for understanding how alkali metals interact with silicon frameworks in high-capacity energy storage systems.
Key Properties
Cross-validated computational properties for KSi, aggregated across 5 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 KSi. 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 KSi, 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. |
|---|---|---|---|---|---|
| — | — | 1.41 | 0.0000 | -0.072 | — |
| P-43n (No. 218) | cubic | 1.26 | 0.0000 | -7.533 | 1.77 |
| — | — | 1.54 | 0.0000 | -0.072 | — |
| I41/acd (No. 142) | tetragonal | 1.66 | 0.0148 | -7.519 | 1.85 |
| — | — | 0.00 | 0.2411 | 0.169 | — |
| — | — | 0.00 | 0.6668 | 0.594 | — |
| — | — | 0.00 | 0.8033 | 0.731 | — |
| — | — | 0.00 | 0.8172 | 0.745 | — |
| — | — | 0.00 | 0.8239 | 0.752 | — |
| Fm-3m (No. 225) | cubic | 0.00 | 1.0283 | 1.022 | — |
| Fm-3m (No. 225) | cubic | 0.00 | 1.2416 | -6.292 | 1.43 |
| — | — | 0.00 | 1.2441 | 1.172 | — |
Applications
Where KSi is used.
Frequently Asked Questions
Common questions about KSi, answered from cross-validated data.
What is KSi?
KSi is a stable, semiconducting binary compound of potassium and silicon used primarily in the study of advanced battery anode materials.
What is KSi used for?
What is the band gap of KSi?
Is KSi a metal, semiconductor, or insulator?
Is KSi thermodynamically stable?
What is the crystal structure of KSi?
What is the density of KSi?
How many polymorphs of KSi are known?
What elements does KSi contain?
Where does the data for KSi come from?
How It Compares
Within the silicon anode materials class.
Within the diverse class of silicon anode materials, KSi stands out for its thermodynamic stability compared to more complex or metastable phases. While elemental Si serves as the industry benchmark, KSi offers a different structural paradigm than binary silicides like Mg2Si or the transition metal silicide MoSi2, providing a unique case study for how alkali-silicon bonding influences electronic properties and structural integrity.
Related Compounds
Other Silicon Anode Materials 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)
- materials_project — Data from the Materials Project (materialsproject.org). Cite: Jain et al., APL Materials 1, 011002 (2013). (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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