Lithium cobalt oxide

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Lithium cobalt oxide[1]
Lithium-cobalt-oxide-3D-balls.png
Lithium-cobalt-oxide-3D-polyhedra.png
Names
IUPAC name
lithium cobalt(III) oxide
Other names
lithium cobaltite
Identifiers
ECHA InfoCard 100.032.135
Properties
LiCoO
2
Molar mass 97.87 g mol−1
Hazards
Main hazards harmful
R-phrases (outdated) R42/43
S-phrases (outdated) S36
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
No verify (what is YesYNo ?)
Infobox references

Lithium cobalt oxide, sometimes called lithium cobaltate[2] or lithium cobaltite[3], is a chemical compound with formula LiCoO
2
. The cobalt atoms are formally in the +3 oxidation state, hence the IUPAC name lithium cobalt(III) oxide.

Lithium cobalt oxide is a dark blue or bluish-gray crystalline solid,[4] and is commonly used in the positive electrodes of lithium-ion batteries.

Structure[edit]

The structure of LiCoO
2
has been studied with numerous techniques including x-ray diffraction, electron microscopy, neutron powder diffraction, and EXAFS[5].

The solid consists of layers of monovalent lithium cations (Li+
) that lie between extended anionic sheets of cobalt and oxygen atoms, arranged as edge-sharing octahedra, with two faces parallel to the sheet plane.[6] The cobalt atoms are formally in the trivalent oxidation state (Co3+
) and are sandwiched between two layers of oxygen atoms (O2−
).

In each layer (cobalt, oxygen, or lithium), the atoms are arranged in a regular triangular lattice. The lattices are offset so that the lithium atoms are farthest from the cobalt atoms, and the structure repeats in the direction perpendicular to the planes every three cobalt (or lithium) layers. The space group is threfore in Hermann-Mauguin notation, signifying a rhombus-like unit cell with threefold improper rotational symmetry and a mirror plane. 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.[7]

Preparation[edit]

Fully reduced lithium cobalt oxide can be prepared by heating a stoichiometric mixture of lithium carbonate Li
2
CO
3
and cobalt(II,III) oxide Co
3
O
4
or metallic cobalt at 600–800°C, then annealing the product at 900°C for many hours, all under an oxygen atmosphere.[6][3][7]

Nanometer-size particles more suitable for cathode use can also be obtained by calcination of hydrated cobalt oxalate β-CoC
2
O
4
·2H
2
O
, in the form of rod-like crystals about 8 μm long and 0.4 μm wide, with lithium hydroxide LiOH, up to 750–900°C.[8]

A third method uses lithium acetate, cobalt acetate, and citric acid in equal molar amounts, in water solution. Heating at 80°C turns the mixture into a viscous transparent gel. The dried gel is then ground and heated gradually to 550°C.[9]

Use in rechargeable batteries[edit]

The usefulness of lithium cobalt oxide as an intercalation electrode was discovered in 1980 by John B. Goodenough's research group at Oxford.[10]

The compound is now used as the cathode in some rechargeable lithium-ion batteries, with particle sizes ranging from nanometers to micrometers.[9][8] During charging, the cobalt is partially oxidized to the +4 state, with some lithium ions moving to the electrolyte, resulting in a range of compounds Li
x
CoO
2
with 0 < x < 1.[3]

Batteries produced with LiCoO
2
cathodes have very stable capacities, but have lower capacities and power than those with cathodes based on nickel-cobalt-aluminum (NCA) oxides. Issues with thermal stability are better for LiCoO
2
cathodes than other nickel-rich chemistries although not significantly. 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.[11] In general, this is seen for many lithium ion battery cathodes.

See also[edit]

References[edit]

  1. ^ 442704 - Lithium cobalt(III) oxide (2012-09-14). "Sigma-Aldrich product page". Sigmaaldrich.com. Retrieved 2013-01-21. 
  2. ^ A. L. Emelina, M. A. Bykov, M. L. Kovba, B. M. Senyavin, E. V. Golubina (2011), "Thermochemical properties of lithium cobaltate". Russian Journal of Physical Chemistry, volume 85, issue 3, pages 357–363; doi:10.1134/S0036024411030071
  3. ^ a b c Ondřej Jankovský, Jan Kovařík, Jindřich Leitner, Květoslav Růžička, David Sedmidubský (2016) "Thermodynamic properties of stoichiometric lithium cobaltite LiCoO2". Thermochimica Acta, volume 634, pages 26-30. doi:10.1016/j.tca.2016.04.018
  4. ^ LinYi Gelon New Battery Materials Co., Ltd, "Lithium Cobalt Oxide (LiCoO2) for lithium ion battery ". Catalog entry, accessed on 2018-04-10,
  5. ^ 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. 
  6. ^ a b Yang Shao-Horn; Laurence Croguennec; Claude Delmas; E. Chris Nelson; 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.
     
  7. ^ a b H. J. Orman & 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.
     
  8. ^ a b Qi, Zhaoxiang (August 2016). "High-Performance LiCoO2 Sub-Micrometer Materials from Scalable Microparticle Template Processing". ChemistrySelect. 1: 3992–3999. 
  9. ^ a b Tang, W.; Liu, L. L.; Tian, S.; Li, L.; Yue, Y. B.; Wu, Y. P.; Guan, S. Y.; Zhu, K. (2010-11-01). "Nano-LiCoO2 as cathode material of large capacity and high rate capability for aqueous rechargeable lithium batteries". Electrochemistry Communications. 12 (11): 1524–1526. doi:10.1016/j.elecom.2010.08.024. 
  10. ^ K. Mizushima, P. C. Jones, P. J. Wiseman, J. B. Goodenough (1980), "Li
    x
    CoO
    2
    (0<x<1): A New Cathode Material for Batteries of High Energy Density". Materials Research Bulletin, volume 15, pages 783–789. doi:10.1016/0025-5408(80)90012-4
  11. ^ Doughty, Daniel; Pesaran, Ahmad. "Vehicle Battery Safety Roadmap Guidance" (PDF). National Renewable Energy Laboratory. Retrieved 19 January 2013. 

External links[edit]