S-Space College of Engineering/Engineering Practice School (공과대학/대학원) Dept. of Material Science and Engineering (재료공학부) Journal Papers (저널논문_재료공학부)
Synthesis and electrochemical properties of layered Li0.9Ni0.45Ti0.55O2
- Kang, Kisuk; Carlier, Dany; Reed, John; Arroyo, Elena M; Ceder, Gerbrand; Croguennec, L; Delmas, C
- Issue Date
- Chemistry of Materials, Vol.15 No.23, pp.4503-4507
- New Li0.9Ni0.45Ti0.55O2 positive electrode materials were synthesized by means of ion exchange from Na0.9Ni0.45Ti0.55O2. Powder X-ray diffraction (XRD) patterns for these materials indicate that they are isostructural with alpha-NaFeO2. The degree of cation disordering in the material depends critically on the synthesis conditions. Higher temperatures and longer ion-exchange times induce more cation disordering. Surprisingly, the partially disordered phase shows better capacity retention than the least disordered phase. First-principles calculations indicated the poor capacity retention in the least disordered phase could be attributed to the migration of Ti4+ into the Li layer during the electrochemical testing. The Ti4+ migration seems to depend sensitively on the Ni2+-Ti4+ configuration in the transition metal layer. Density of states (DOS) obtained from first-principles calculations indicate that only Ni participates in the electronic conductivity and that the poor conductivity of this material could be another reason for its low specific capacity.
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