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

Doped Li(1.05)M(0.02M)n(1.98)O(4) (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 (Mn-1.98 + M-0.02) to 1.05 Li. The TGA/DTA of the precursor gels showed weight loss/energy relative to crystallization below 450 degrees C. From the XRD, a single cubic phase (F-D3M) 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 degrees C for 2 h (8.212 angstrom and 8.210 angstrom, respectively) were higher than that for the undoped oxide (8.199 angstrom). The crystallite sizes ranged from similar to 20 nm to 70 nm, conferring nanometric character. The specific capacities decreased in order: C-discharge (Li1.05Mn2O4) > C-discharge (Li1.05Ga0.02Mn1.98O4) > C-discharge (Li1.05Al0.02Mn1.98O4), but with increasing capacity retention for the doped samples.