Lithium peroxide is the inorganic compound with the formulaLi2O2. 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]
This lithium hydroperoxide has also been described as lithium peroxide monoperoxohydrate trihydrate (Li2O2·H2O2·3H2O).
Dehydration of this material gives the anhydrous peroxide salt:
2 LiOOH → Li2O2 + H2O2
Li2O2 decomposes at about 450 °C to give lithium oxide:
2 Li2O2 → 2 Li2O + O2
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]
Uses
It is used in air purifiers where weight is important, e.g., spacecraft to absorb carbon dioxide and release oxygen in the reaction:[4]
Li2O2 + CO2 → Li2CO3 + 1⁄2 O2
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.
^"Physical Constants of Inorganic Compounds," in CRC Handbook of Chemistry and Physics, 91st Edition (Internet Version 2011), W. M. Haynes, ed., CRC Press/Taylor and Francis, Boca Raton, Florida. (pp: 4-72).
^E. Dönges "Lithium and Sodium Peroxides" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 979.
^L. G. Cota and P. de la Mora "On the structure of lithium peroxide, Li2O2" Acta Crystallogr. 2005, vol. B61, pages 133-136. doi:10.1107/S0108768105003629
^Ulrich Wietelmann, Richard J. Bauer "Lithium and Lithium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH: Weinheim. doi:10.1002/14356007.a15_393.pub2
^Girishkumar, G.; B. McCloskey; AC Luntz; S. Swanson; W. Wilcke (July 2, 2010). "Lithium- air battery: Promise and challenges". The Journal of Physical Chemistry Letters. 1 (14): 2193–2203. doi:10.1021/jz1005384.
^[1] Patent-pending device invented at The Ohio State University: the world’s first solar battery.
