Pechini synthesis of nanostructured Li1.05M0.02Mn1.98O4 (M = Al3+ or Ga3+)

Abstract

Doped Li1.05M0.02Mn1.98O4 (M = Ga3+ or Al3+) were prepared by Pechini synthesis using lithium and manganese acetates, citric acid, ethylene glycol, and the respective oxide or acetate of the doping ions in molar ratios of 2.00 (Mn1.98 + M0.02) to 1.05 Li. The TGA/DTA of the precursor gels showed weight loss/energy relative to crystallization below 450 °C. From the XRD, a single cubic phase (FD3M) was identified for the all-doped or undoped oxides after only 2 h calcination. The unit cell parameters a for both aluminum-and gallium-doped oxides calcined at 750 °C for 2 h (8.212 Å and 8.210 Å, respectively) were higher than that for the undoped oxide (8.199 Å). The crystallite sizes ranged from ∼ 20 nm to 70 nm, conferring nanometric character. The specific capacities decreased in order: Cdischarge (Li1.05Mn2O4) >Cdischarge (Li1.05Ga0.02Mn1.98O4) >Cdischarge (Li1.05Al0.02Mn1.98O4), but with increasing capacity retention for the doped samples.