Investigation of the possible incorporation of protons into oxide cathodes during chemical delithiation

Chemical delithiation of layered LiCoO2, LiNi0.5Mn0.5O2, and Li2MnO3 and spinel LiMn2O4 cathodes have been investigated with both an acetonitrile (non-aqueous) solution of the oxidizer NO2BF4 and an aqueous acid. The products have been characterized by X-ray diffraction, wet chemical analyses for lithium and oxygen contents, infrared spectroscopy, and thermogravimetric analysis to determine whether or not protons are incorporated into the lattice during the delithiation process. While the delithiation in aqueous acid medium leads to an incorporation of protons into the layered oxide lattice, the non-aqueous delithiation with NO2BF4 does not involve any proton insertion into the lattice. In contrast to the layered oxides, the chemical delithiation of spinet LiMn2O4 even in the aqueous acid medium does not involve any proton insertion into the lattice. (C) 2004 Elsevier Inc. All rights reserved.