Determination of the synthesis diagram of sodium cobalt oxide and electrochemical study

A complete and uniform synthesis diagram of NaxCoO₂ has been proposed based on forty-one samples synthesized at various temperatures from 450°C to 750°C by solid-state reactions with initial Na:Co ratio ranging from 0.60 to 1.05. Four monophasic domains of' O3, O3', P3' and P2 and four biphasic regions were revealed based on an XRD analysis. The sodium contents in these phases were determined according to the d00j-x relations obtained by an in situ XRD experiment and it is found O3, O3' and P3' phase almost form with only one stoichiometry, that is x=1.00, 0.83 and 0.67 respectively, by solid-state reaction while P2 phase forms in a slightly larger composition range from 0.68 to 0.76. Galvanostatic charging on O3-Na₁.₀₀CoO₂ battery reveals several plateaus and steep steps on the voltage curve, the corresponding phase transitions and solid solution behaviors were studied by a simultaneous in situ XRD experiment. The composition driven structural evolution in three layer NaXCoO₂ follows the sequence: O3-O3'-P3'-P3-P3', with a generally increased interslab distance d₀₀l.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Materials Science and Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2014

Author dc:creator

• Lei, Yuechuan

Advisor dc:contributor.advisor

• Gerbrand Ceder.

• Materials Science and Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/89985

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/89985