The effects of heat-treatment temperature on the retention capacities of spinels prepared by the Pechini process

Abstract

Stoichiometric LiMn 2O 4 was prepared by the Pechini method and heat-treated at temperatures between 600 and 800 °C for 8 h. Crystalline structures and the electrochemical properties of the prepared samples were investigated. The sample heat-treated at 600 °C shows a trace amount of Mn 2O 3 with predominant spinel, whereas those prepared at temperatures between 700 and 800 °C show exclusively spinel with similar lattice constants. The crystallinity index calculated from the (1 1 1) peak of XRD pattern increases with increasing heat-treatment temperature. All of the prepared samples show similar capacity fading rate. On the same cycle number, the specific capacity increases with increasing temperature of heat-treatment. It is found that samples with similar lattice constant exhibit similar specific discharging capacity on the same cycle number and similar fading rate at the high voltage plateau. The crystallinity index and the initial specific discharge capacity on the low-voltage plateau increase with increasing heat-treatment temperature.