Designing new electrode materials for energy devices by integrating ab initio computations with experiments

Utilization of Ni2+/Ni4+ double redox couple in electrochemical reactions has been tested as a way to gauge useful properties such as high capacity in electrode materials. The feasibility of a Ni2+/Ni4+ active redox couple is confirmed in a new layered electrode material, Lio.gNi045Ti5502. First principles calculations combined with experiments show that the degree of cation disordering in the material arising from both synthesis conditions and the electrochemical reaction is critical in performance of this material as the electrode. In an attempt to fully utilize Ni2+/Ni4+ double redox couple, Li2NiO2 in the Immm structure was successfully synthesized and its electrochemical behavior upon delithiation was evaluated. The material shows a high specific charge capacity of about 320 mAh/g and discharge capacity of about 240 mAh/g at the first cycle. The stability of Li2NiO2 in the Immm structure is attributed to the more favorable Li arrangement possible as compared to a Li2NiO2 structure with octahedral Ni. The electrochemical data, first principles calculation and EXAFS analysis all indicate that the orthorhombic Immm structure is rather prone to phase transformation to a close-packed layered structure during the electrochemical cycling.

Department dc:contributor.department

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

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Kang, Kisuk

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/1721.1/36213

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/36213