Nanosized LiMYMn2−YO4 (M=Cr, Co and Ni) spinels synthesized by a sucrose-aided combustion method
2007; Elsevier BV; Volume: 174; Issue: 2 Linguagem: Inglês
10.1016/j.jpowsour.2007.06.056
ISSN1873-2755
AutoresJosé Manuel Amarilla, R.M. Rojas, Fernando Picó, L. Pascual, Κ. Petrov, Daniela Kovacheva, M. G. Lazarraga, I. Lejona, J. M. Rojo,
Tópico(s)Supercapacitor Materials and Fabrication
ResumoSpinels of composition LiMYMn2−YO4, M = Cr3+, Co3+, or Ni2+, Y = 0.1 and 1 for the Cr and Co dopants, Y = 0.05 and 0.5 for the Ni sample, have been synthesized by a sucrose-aided combustion method. The samples as prepared require of an additional thermal treatment at 700 °C, 1 h to get stoichiometric single-phase spinels. The samples consist of aggregated particles of small size (45–50 nm) as deduced from transmission electron microscopy and X-ray powder diffraction. The electrochemical behaviour of the six spinels as cathodes in lithium cells has been analysed at 5 and 4 V under high current, 1 C rate. At 5 V the discharge capacity of LiNi0.5Mn1.5O4 is higher than the one shown by LiCrMnO4 and LiCoMnO4, and it shows an elevated cyclability, i.e. capacity retention of 85.3% after 100 cycles. At 4 V the discharge capacity is similar for LiNi0.05Mn1.95O4, LiCr0.1Mn1.9O4 and LiCo0.1Mn1.9O4, and all the three spinels show similar and very high cyclability, i.e. capacity retention >90% after 100 cycles. The spinels preserve their starting capacity up to currents as high as 2 C rate. The nanometric size of the samples explains the high rate capability of the synthesized spinels.
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