| Autor: |
Lee, K.-S., Myung, S.-T., Amine, K., Yashiro, H., Sun, Y.-K. |
| Předmět: |
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| Zdroj: |
Journal of The Electrochemical Society; Oct2007, Vol. 154 Issue 10, pA971-A977, 7p, 1 Chart, 12 Graphs |
| Abstrakt: |
Structural and electrochemical properties of Li[Ni1-2xCoxMnx]O2 (x = 0.1-0.3) as positive electrode materials for lithium batteries were investigated. The materials were prepared via a coprecipatation process. From X-ray diffraction studies, it was found that the synthesized materials were crystallized into an α-NaFeO2 layered structure (R3m). With increasing Co and Mn content in Li[Ni1-2xCoxMnx]O2, the corresponding lattices were slightly contracted. X-ray absorption near edge spectra of Li[Ni1-2xCoxMnx]O2 (x = 0.1-0.3) also showed that the oxidation state of Ni is changed from 3+ to 2+ when tetravalent Mn is present in Li[Ni1-2xCoxMnx]O2 oxide (x = 0.2-0.3). From Rietveld refinements of powder X-ray diffraction data, it was found that further increase in Co and Mn content also resulted in reduced cation mixing between Li+ and Ni2+ in Li layers. Electrochemical properties and thermal stability were also affected by the physical properties. When tetravalent Mn appeared in the structure, the corresponding cyclability was greatly improved compared to that of Li[Ni0.8Co0.1Mn0.1]O2. Furthermore, thermal stability at highly delithiated state was also significantly enhanced by the existence of electrochemically inactive tetravalent Mn in the oxide matrix. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Supplemental Index |
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