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Names | |
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Other names
Dilithium peroxide
Lithium (I) peroxide Dilithium Dioxide | |
Identifiers | |
3D model (JSmol)
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ChemSpider | |
ECHA InfoCard | 100.031.585 |
PubChem CID
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
Li2O2 | |
Molar mass | 45.881 g/mol |
Appearance | fine, white powder |
Odor | odorless |
Density | 2.31 g/cm3[1][2] |
Melting point | Decomposes to Li2O at ~340°C [3] |
Boiling point | NA |
soluble[vague] | |
Structure | |
hexagonal | |
Thermochemistry | |
Std enthalpy of
formation (ΔfH⦵298) |
-13.82 kJ/g |
Hazards | |
GHS labelling: | |
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Danger | |
H271, H272, H314 | |
P210, P220, P221, P260, P264, P280, P283, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P306+P360, P310, P321, P363, P370+P378, P371+P380+P375, P405, P501 | |
NFPA 704 (fire diamond) | |
Related compounds | |
Other cations
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Sodium peroxide Potassium peroxide Rubidium peroxide Caesium peroxide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Lithium peroxide is the inorganic compound with the formula Li2O2. It is a white, nonhygroscopic solid. Because of its high oxygen:mass and oxygen:volume ratios, the solid has been used to remove CO2 from the atmosphere in spacecraft.[4]
It is prepared by the reaction of hydrogen peroxide and lithium hydroxide. This reaction initially produces lithium hydroperoxide:[4][5]
This lithium hydroperoxide has also been described as lithium peroxide monoperoxohydrate trihydrate (Li2O2·H2O2·3H2O). Dehydration of this material gives the anhydrous peroxide salt:
Li2O2 decomposes at about 450 °C to give lithium oxide:
The structure of solid Li2O2 has been determined by X-ray crystallography and density functional theory. The solid features an eclipsed "ethane-like" Li6O2 subunits with an O-O distance of around 1.5 Å.[6]
It is used in air purifiers where weight is important, e.g., spacecraft to absorb carbon dioxide and release oxygen in the reaction:[4]
It absorbs more CO2 than does the same weight of lithium hydroxide and offers the bonus of releasing oxygen.[7] Furthermore, unlike most other alkali metal peroxides, it is not hygroscopic.
The reversible lithium peroxide reaction is the basis for a prototype lithium–air battery. Using oxygen from the atmosphere allows the battery to eliminate storage of oxygen for its reaction, saving battery weight and size.[8]
The successful combination of a lithium-air battery overlain with an air-permeable mesh solar cell was announced by The Ohio State University in 2014.[9] The combination of two functions in one device (a "solar battery") is expected to reduce costs significantly compared to separate devices and controllers as are currently employed.