Lithium cobalt oxide

Lithium cobalt oxide^[1]

Names
IUPAC name lithium cobalt(III) oxide
Other names lithium cobaltite
Identifiers
CAS Number	12190-79-3
PubChem	23670860
Properties
Chemical formula	LiCoO 2
Molar mass	97.87 g mol^−1
Hazards
Main hazards	harmful
R-phrases	R42/43
S-phrases	S36
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Lithium cobalt oxide (LiCoO
2) is a chemical compound commonly used in the positive electrodes of lithium-ion batteries. The structure of LiCoO
2 is known theoretically and has been confirmed with techniques like x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS:^[2] it consists of layers of lithium that lie between slabs of octahedra formed by cobalt and oxygen atoms.^[3] The space group is $R\bar 3m$^[4] in Hermann-Mauguin notation, signifying a rhombus-like unit cell with threefold improper rotational symmetry and a mirror plane. More simply, however, both lithium and cobalt are octahedrally coordinated by oxygen. These octahedrons are edge-sharing, and tilted relative to the layered structure. The threefold rotational axis (which is normal to the layers) is termed improper because the triangles of oxygen (being on opposite sides of each octahedron) are anti-aligned.

Batteries produced with LiCoO
2 cathodes, while providing higher capacity, are more reactive and have poorer thermal stability than chemistries such as the newer lithium-nickel-cobalt-aluminum-oxide types. This makes LiCoO
2 batteries susceptible to thermal runaway in cases of abuse such as high temperature operation (>130 °C) or overcharging. At elevated temperatures, LiCoO
2 decomposition generates oxygen, which then reacts with the organic electrolyte of the cell. This is a safety concern due to the magnitude of this highly exothermic reaction, which can spread to adjacent cells or ignite nearby combustible material.^[5]

The compound's usefulness as an intercalation electrode was discovered in 1980^[6] by John B. Goodenough's research group at Oxford.

References

1. 442704 - Lithium cobalt(III) oxide (2012-09-14). "Sigma-Aldrich product page". Sigmaaldrich.com. Retrieved 2013-01-21.
2. I. Nakai, K. Takahashi, Y. Shiraishi, T. Nakagome, F. Izumi, Y. Ishii, F. Nishikawa, T. Konishi (1997). "X-ray absorption fine structure and neutron diffraction analyses of de-intercalation behavior in the LiCoO2 and LiNiO2 systems". Journal of Power Sources 68 (2): 536–539. doi:10.1016/S0378-7753(97)02598-6.
3. Yang Shao-Horn, Laurence Croguennec, Claude Delmas, E. Chris Nelson and Michael A. O'Keefe (July 2003). "Atomic resolution of lithium ions in LiCoO
   2". Nature Materials 2 (7): 464–467. doi:10.1038/nmat922. PMID 12806387.
4. H. J. Orman and P. J. Wiseman (January 1984). "Cobalt(III) lithium oxide, CoLiO
   2: structure refinement by powder neutron diffraction". Acta Crystallographica Section C 40 (1): 12–14. doi:10.1107/S0108270184002833.
5. Doughty, Daniel; Pesaran, Ahmad. "Vehicle Battery Safety Roadmap Guidance" (PDF). National Renewable Energy Laboratory. Retrieved 19 January 2013.
6. K. Mizushima, P.C. Jones, P.J. Wiseman, J.B. Goodenough (1980). "Li
   xCoO
   2 (0<x<l): A NEW CATHODE MATERIAL FOR BATTERIES OF HIGH ENERGY DENSITY". Materials Research Bulletin 15: 783–789. doi:10.1016/0025-5408(80)90012-4.

External links

• Imaging the Structure of Lithium Cobalt Oxide at Atomic Level