期刊
JOURNAL OF POWER SOURCES
卷 205, 期 -, 页码 385-393出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jpowsour.2011.12.037
关键词
Lithium ion batteries; Spinel; Trivalent transition metal doping; Lithium nickel manganese oxide; Thermopolymerization
资金
- National Science Foundation of China [20971117, 10979049, J1030412]
- Education Department of Anhui Province [KJ2009A142]
LiNi0.5Mn1.5O4 and LiNi0.45M0.10Mn1.45O4 (M = Fe, Co, Cr) powders are prepared and systematically investigated as 5V cathode materials for lithium-ion batteries. X-ray diffraction, Raman spectroscopy and scanning electron microscopy are employed to study their structures. The electrochemical cyclic performance and rate capability at room temperature and 55 degrees C are characterized and compared. The results indicate that the introductions of Fe. Co or Cr ions favor the crystal structure of the spinet in a Fd (3) over barm symmetry compared with a symmetry of P4(3)32 for the un-doped LiNi0.5Mn1.5O4. Excellent cycle life is measured for these 5 V Co- and Fe-doped electrodes. When cycled at 1C rate, about 95.9%, 93.1% and 81.7% of their initial capacities can be retained after 500 cycles for LiNi0.45Co0.10Mn1.45O4, LiNi0.45Fe0.10Mn1.45O4 and LiNi0.45Cr0.10Mn1.45O4, respectively. Their electrochemical performances at 55 degrees C are also much better than the un-doped sample. Three possible capacity fading mechanisms including structural transformation, the dissolution of the spinel into the electrolyte, and the oxidation of the electrolyte are discussed. The decomposition of the electrolyte is regarded as the most important mechanism. (C) 2011 Elsevier B.V. All rights reserved.
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