中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 16 No. 2 April 2006 |
（1. School of Chemistry and Chemical Engineering, Central South University, Changsha 410083, China
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China）
Abstract:The phase transition of Li2Mn2O4 spinel at high temperature was investigated by XRD, TG/DTA, average oxidation state of Mn and cyclic voltammeric techniques. The results reveal that the Li2Mn2O4 spinel is unstable. At high temperature, it is easy to transform into [Li2-2x]tet[Mn2-xLix]octO4, which accompanies the formation of Li2MnO3 impurities. The phase transition is associated with the transfer of Li+ from tetrahedral 8a sites to octahedral 16d sites. With the increasing sintering temperature from 450 ℃ to 850 ℃, the phase structure varies from lithiated-spinel Li2Mn2O4 to Li4Mn5O12-like to LiMn2O4-like and finally to rock-salt LiMnO2-like. In addition, a way of determining x with average oxidation state of Mn and the content of Li2MnO3 was also demonstrated.
Key words: lithium manganese oxide; Li2Mn2O4; phase transition; lithium-ion batteries
