Failure mechanism and improvement of the elevated temperature cycling of LiMn2O4 compounds through the use of the LiAlxMn2-xO4-zFz solid solution

Physiochemical and electrochemical means were used to characterize the failure mechanisms of the lithium manganese oxide based solid solutions utilized as positive electrodes for Li batteries. Resultant data supports a theory in which the 22 and 55 degreesC failure mechanisms are one in the same. The poor performance is exacerbated during cycling due to a mechanism linked to the symbiotic relationship between physical destruction induced by a surface Jahn-Teller distortion and the classic failure mechanisms presented for the chemical failure of the spinel at elevated temperature storage. Based on these findings, a spinel, LiAlxMn2-xO4-zFz, was fabricated which exhibits enhanced stability at elevated temperature. (C) 2001 Telcordia Technologies. All rights reserved.