Synthesis of lithium-manganese-oxide spinels: A study by thermal analysis

Abstract

The synthesis of lithium-manganese-oxide spinels by reaction of Li2CO3 and MnCO3 in air and under nitrogen to T(max) = 600°C has been investigated by thermogravimetric analysis and differential scanning calorimetry. When the reaction is conducted in air, the stoichiometric spinel LiMn2O4 is produced via a series of intermediate ''oxygen-rich,'' defect spinel compounds XLi1-xMn2-2xO4 (0 < = X < = 0.11), whereas under nitrogen the reaction proceeds more directly to LiMn2O4. The study has demonstrated that lithium-manganese-oxide spinel compounds that fall within the solid solution range XLi1-xMn2-2xO4 (0 < = X < = 0.11) can be synthesized by reaction of MnCO3 and Li2CO3 in air at moderate temperatures. It is difficult, however, to control the reaction parameters, for example, temperature and time, to produce a spinel compound with a predetermined stoichiometry. The study has, however, illustrated that the stoichiometric spinel LiMn2O4 can be produced at a moderately low temperature (less than 500°C) by performing the reaction under nitrogen. This result has commercial implications for the production of LiMn2O4 which, in the past, has been conventionally synthesized in air at higher temperatures, for example, 700-850°C