Structure, morphology and electrochemistry of doped lithium cobalt oxides

Abstract

The structure, morphology and electrochemical performance of LiCoO2 powders doped with various trivalent cations such as M3+=Ni3+, Al3+, and B3+ have been investigated. X-ray diffraction patterns and FTIR data show that LiCo1−yNiyO2 oxides display a solid solution in the whole range 0≤y≤1, while the solubility limit of LiCo1−yAlyO2 and LiCo1−yByO2 materials is about y=0.35. Electrochemical features of LiCo1−yNiyO2 cathode materials show remarkable stability in their charge-discharge profiles. Aluminum substitution also stabilizes the two-dimensional framework and induces an increasing average cell potential than for LiCoO2. The overall capacity of the LiCo1−yByO2 oxides has been reduced due to the sp metal substitution, however, a more stable charge-discharge cycling characteristic has been observed when electrodes are charged up to 4.4 V as compared to the performances of the native oxides.