Structural characteristics and electrochemical performance of layered Li[Mn0.5−xCr2xNi0.5−x]O2 cathode materials
2008; Elsevier BV; Volume: 187; Issue: 2 Linguagem: Inglês
10.1016/j.jpowsour.2008.11.061
ISSN1873-2755
AutoresN. K. Karan, Mahalingam Balasubramanian, Daniel P. Abraham, M.M. Furczon, Dillip K. Pradhan, José Javier Saavedra-Arias, Reji Thomas, Ram S. Katiyar,
Tópico(s)Supercapacitor Materials and Fabrication
ResumoLi[Mn0.5−xCr2xNi0.5−x]O2 (0 < 2x <0.2) (Mn/Ni = 1) cathode materials have been synthesized by a solution method. X-ray diffraction patterns of the as-prepared materials were fitted based on a hexagonal unit cell (α-NaFeO2 layer structure). The extent of Li/Ni intermixing decreased, and layering of the structure increased, with increasing Cr content. Electrochemical cycling of the oxides, at 30 °C in the 3–4.3 V range vs. Li/Li+, showed that the first charge capacity increased with increasing Cr content. However, maximum discharge capacity (∼143 mAh g−1) was observed for 2x = 0.05. X-ray absorption near edge spectroscopic (XANES) measurements on the K-edges of transition metals were carried out on pristine and delithiated oxides to elucidate the charge compensation mechanism during electrochemical charging. The XANES data revealed simultaneous oxidation of both Ni and Cr ions, whereas manganese remains as Mn4+ throughout, and does not participate in charge compensation during oxide delithiation.
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