Item Details

abstract

Crystals of LiFePO4 and related materials have recently received a lot of attention due to their very promising use as cathodes in rechargeable lithium ion batteries. This thesis studied the electronic structures of FePO4 and LiMPO4, where M=Mn, Fe, Co and Ni within the framework of density-functional theory. The ¯rst study compared the electronic structures of the LiMPO4 and FePO4 materials in their electrochemically active olivine form, using the LAPW (linear aug- mented plane wave) method [1]. A comparison of results for various spin con¯gura- tions suggested that the ferromagnetic con¯guration can serve as a useful approxima- tion for studying general features of these systems. The partial densities of states for the LiMPO4 materials are remarkably similar to each other, showing the transition metal 3d states forming narrow bands above the O 2p band. By contrast, in absence of Li, the majority spin transition metal 3d states are well-hybridized with the O 2p band in FePO4. The second study compared the electronic structures of FePO4 in several crys- tal structures including an olivine, monoclinic, quartz-like, and CrVO4-like form [2, 3]. For this work, in addition to the LAPW method, PAW (Projector Augmented Wave) [4], and PWscf (plane-wave pseudopotential) [5] methods were used. By care- fully adjusting the computational parameters, very similar results were achieved for the three independent computational methods. Results for the relative stability of the four crystal structures are reported. In addition, partial densities of state analyses show qualitative information about the crystal ¯eld splittings and bond hybridizations and help rationalize the understanding of the electrochemical and stability properties of these materials.

subject

lithium ion battery

contributor

Tang, Ping (author)

tangp.tp@gmail.com (authorEmail)

Akbar Salam (committee chair)

Natalie A. W. Holzwarth (committee member)

Keith D. Bonin (committee member)

Greg Cook (committee member)

G. Eric Matthews (committee member)

creator

Tang, Ping

date

2008-09-28T10:54:10Z (accessioned)

2010-06-18T18:59:26Z (accessioned)

2008-11-13 (available)

2008-09-28T10:54:10Z (available)

2010-06-18T18:59:26Z (available)

2006-08-01 (issued)

degree

null (defenseDate)

Physics (discipline)

Wake Forest University (grantor)

PHD (level)

identifier

PingTang2006.pdf

http://hdl.handle.net/10339/14852 (uri)

migration

etd-09252007-104445 (oldETDId)

rights

Release the entire work immediately for access worldwide. (accessRights)

I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to Wake Forest University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. (license)

title

Computational Research on Lithium Ion Battery Materials