Key points are not available for this paper at this time.
A survey of the chemical stability of high-surface area LiMnsub 2Osub 4 in various Li-based electrolytes was performed as a function of temperature. The evidence for an acidic-induced Mn dissolution was confirmed, but more importantly the authors identified, by means of combined infrared spectroscopy, thermogravimetric analysis, and X-ray diffraction measurements, the growth, upon storage of LiMnsub 2Osub 4 in the electrolyte at 100 C, of a protonated lambda-MnOsub 2 phase partially inactive with respect to lithium intercalation. This results sheds light on how the mechanism of high temperature irreversible capacity loss proceeds. Mn dissolution first occurs, leading to a deficient spinel having all the Mn in the +4 oxidation state. Once this composition is reached, Mn cannot be oxidized further, and a protonic ion-exchange reaction takes place at the expense of the delithiation reaction. The resulting protonated lambda-Mnsub 2{minusy}Osub 4 phase has a reduced capacity with respect to lithium, thereby accounting for some of the irreversible capacity loss experienced at 55 C for such a material.
Pasquier et al. (Mon,) studied this question.