Combined first-principle calculations and experimental study on multi-component olivine cathode material = 리튬 이차전지 양극 재료용 다성분계 올리빈 구조 물질에 대한 제일계산과 실험을 접목한 연구

The electrochemical properties and phase stabilities of the multi-component olivine compound $LiMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$ are studied experimentally and with first-principles calculation. The formation of the solid solution between $LiMnPO_4$, $LiFePO_4$, and $LiCoPO_4$ at this composition is confirmed by XRD patterns and the calculated energy. The experimental and first principle results indicate that there are three distinct regions in the electrochemical profile at quasi-open-circuit potentials of ~3.5 V, ~4.1 V, and ~4.7 V, which are attributed to $Fe^{3+}/Fe^{2+}$, $Mn^{3+}/Mn^{2+}$, and $Co^{3+}/Co^{2+}$ redox couples, respectively. However, exceptionally large polarization is observed only for the region near 4.1 V of $Mn^{3+}/Mn^{2+}$ redox couples, implying an intrinsic charge transfer problem. An ex situ XRD study reveals that the reversible one-phase reaction of Li extraction/insertion mechanism prevails, unexpectedly, for all lithium compositions of $LixMn_{1/3}Fe_{1/3}Co_{1/3}PO_4$ $(0 \le x \le 1)$ at room temperature. This is the first demonstration that the well-ordered, non-nanocrystalline (less than 1% Li - M disorder and a few hundred nanometer size particle) olivine electrode can be operated solely in a one-phase behavior.
Advisors
Kang, Ki-Sukresearcher강기석researcher
Publisher
한국과학기술원
Issue Date
2010
Identifier
419145/325007  / 020083039
Language
eng
Description

학위논문(석사) - 한국과학기술원 : 신소재공학과, 2010.2, [ iv, 72 p. ]

Keywords

first-principle calculations; olivine; lithium battery; one-phase reaction; 단일상 반응; 제일계산; 올리빈; 리튬 전지

URI
http://hdl.handle.net/10203/51346
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=419145&flag=t
Appears in Collection
MS-Theses_Master(석사논문)
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