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제112회 대한화학회 학술발표회, 총회 및 기기전시회 안내 Doping Effect of NaNi0.5Mn0.5O2 for Enhanced Electrochemical Properties

2013년 8월 29일 17시 11분 12초
MAT.P-1084 이곳을 클릭하시면 발표코드에 대한 설명을 보실 수 있습니다.
10월 16일 (수요일) 16:00~19:00
저자 및
배은경, 표명호*
순천대학교 화학과, Korea
NaNi0.5Mn0.5O2 (NNMO), which has a layered structure, is a promising cathode material for sodium ion batteries. It is well known that the substitution of Mn with Ni in LiNi0.5Mn0.5O2, renders Li+ ion diffusion kinetics better. In a layered structure of LiNi0.5Mn0.5O2, the stack of Mn(Ni)O2 slabs, which are composed of edge-shared Mn(Ni)O6 octahedra, form the metal-occupied octahedral sites and the empty tetrahedral sites. The octahedral sites in Li slabs are also occupied by Li+ ions, which are sandwiched by edge-sharing with Mn(Ni)O2 slabs. Li+ ions move from one octahedral site to another by passing through the empty tetrahedral sites within a Li slab. During this process, Li+ ions are strongly repelled from a nearby transition-metal cations (Mn4+, Ni2+) of octahedral sites. The activation energy is rapidly increased at this moment, which aggravates Li+ ion diffusion kinetics. By using rare earth metals (Gd, Tb), the activation energy and the repulsive force could be decreased, leading to substantial improvement of the Li+ diffusion kinetics and, thereby, charge-discharge rates. Expecting that the same rule can be applied to Na+, we are currently focusing on the synthesis of phase-pure Tb-doped NNMO and the comparison of electrochemical properties of pertinent Tb-doped NNMO cathodes.