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

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

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 ºC. 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.

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Bibliographic Details
Main Authors: Amaral,Fábio Augusto, Santana,Laiane Kálita, Campos,Iury Oliveira, Fagundes,Wélique Silva, Xavier,Farlon Felipe Silva, Canobre,Sheila Cristina
Format: Digital revista
Language:English
Published: ABM, ABC, ABPol 2015
Online Access:http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392015000800250
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Summary: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 ºC. 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.

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