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 fail ure mechanisms of the lithium manganese oxide based solid solutions utilize d 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. Th e poor performance is exacerbated during cycling due to a mechanism linked to the symbiotic relationship between physical destruction induced by a sur face Jahn-Teller distortion and the classic failure mechanisms presented fo r the chemical failure of the spinel at elevated temperature storage. Based on these findings, a spinel, LiAlxMn2-xO4-zFz, was fabricated which exhibi ts enhanced stability at elevated temperature. (C) 2001 Telcordia Technolog ies. All rights reserved.