In situ XRD study of Li deintercalation from two different types of LiMn2O4 spinel

A mechanism of the capacity loss in LiMn2O4 was studied by comparison of tw o types of spinel with different morphologies and specific surface areas (2 .9 and 0.8 m(2) g(-1)). The combination of SSCV and in situ XRD techniques shows that the irreversible structural conversion occurs partially in spine l of the low specific surface area during the first Li deintercalation at a potential 4.0 V. This conversion is mainly responsible for the capacity lo ss in this type of spinel. It seems that these peculiarities of the electro chemical behavior are related to the presence of the layered component in t his material. In contrast, spinel of the high specific surface area present s an example of a stable material without considerable variation of its cap acity and XRD patterns after long-term cycling. This type of spinel demonst rates two distinct phase transitions in the vicinity of 4.0-4.1 V, correspo nding to two SSCV peaks. (C) 1999 Elsevier Science B.V. All rights reserved .