Crystallization mechanism of sol‐gel synthesized spinel LiMn2O4

Abstract Crystallization mechanism of sol‐gel synthesized spinel LiMn 2 O 4 is studied by a differential scanning calorimetry (DSC) method. Lithium acetate and manganese acetate are dissolved in methanol in the atomic ratio of 1:2 (Li:Mn) with citric acid as a chelating agent, leading to a sol solution. A Li‐Mn gel precursor is obtained by partly evaporating the sol solution. A large exothermic reaction of the Li‐Mn gel starts at 280 °C, indicating that the combustions of C and H atoms released from the gel occur above 280 °C. After the rise in temperature to 290 °C, the exothermic reaction of the gel continues at the constant temperature of 290 °C, indicating that the rearrangement of Li, Mn and O atoms for the crystallization into the spinel structure mainly occurs at 290 °C. This suggests that annealing the Li‐Mn gel precursor above 290 °C is necessary to obtain spinel LiMn 2 O 4 . During the exothermic reaction, Mn atoms released from the gel occupy the octahedral sites in the spinel framework of O, and Li atoms also released are inserted into the tetrahedral sites. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)