Electrochemical performance of nanostructured LiMxMn2-xO4 (M=Co and Al) powders at high charge-discharge operations

Nanostructured LiMxMn2-xO4(M=Co and Al, 0 <= x <= 0.3) powders were successfully synthesized by an ultrasonic spray pyrolysis technique from the precursor solutions; LiNO3, Mn(NO3)(2) (.) 6H(2)O and Co(NO3)(2) (.) 6H(2)O or Al(NO3)(3) (.) 9H(2)O were stoichiometrically dissolved into distilled water. The product characteristics such as crystallinity, specific surface area, particle morphology and interior structure of particles, were examined with X-ray diffraction (XRD), the Brunauer-Emmet-Teller (BET) method, field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), respectively. The chemical composition of the samples was also performed by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The resulting powders were spherical nanostructered particles, which comprised of the primary particles with a few tens of nanometers in sizes. All the samples exhibited a pure cubic spinel structure without any impurities in the XRD patterns, while the surface morphology of as-prepared powders changed from porous to smooth microstructure with the amount of Co or Al substitution. The as-prepared samples were sintered at 750 degrees C for 4 h in air. However, the particles morphology and pure spinel phase of nanostructured LiMxMn2-xO4(M=CO and Al)powders did not change after sintering. The as-sintered samples were used as cathode active materials for lithium-ion battery, and electrochemical studies were carried out on the charge/discharge characteristics of the Li/LiMxMn2-xO4(M=Co and Al) cells at room temperature. (c) 2005 Elsevier B.V. All rights reserved.