XPS Study on Al[sub 2]O[sub 3]- and AlPO[sub 4]-Coated LiCoO[sub 2] Cathode Material for High-Capacity Li Ion Batteries

The impact of aluminum oxide coatings on materials for commercial lithium ion batteries has been investigated by X-ray photoelectron spectroscopy (XPS). A low binding energy component in the core peak spectra was observed and attributed to the formation of a solid solution interphase for both - and -coated . The surface chemistry of pristine and -coated cathodes and graphite anodes have been investigated after cycling up to or cutoff voltage and after various levels of capacity fade. The coating enhances the capacity retention at both and cutoff voltages. XPS analyses provided evidence of the inhibition of cobalt dissolution from the positive electrode by the aluminum coatings. Moreover, the coating lowers the kinetics of degradation of electrolyte species, especially the salt.