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)2·6H2O and Co(NO3)2·6H2O or Al(NO3)3 · 9H2O 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 °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.