~6Li MAS NMR and in situ X-ray studies of lithium nickel manganese oxides

摘要

In situ XRD and ~6Li MAS NMR spectroseopy have been carried out during the first charge process for the layered cathode material Li[Li_(1/9)Ni_(3/9)Mn_(5/9)]O_2. In situ XRD results showed that the c-parameters of the Li[Li_(1/9)Ni_(3/9)Mn_(5/9)]O_2 material increase only slightly at the end of charge. The Mn and Ni K-edge EXAFS results revealed that this compound contains localized clusters resembling the local environments found in Li_2MnO_3 and lithium nickel oxide. The ~6Li MAS NMR results showed the presence of Li in the Ni~(2+)/Mn~(4+) layers, in addition to the expected sites for Li in the lithium layers. All the Li ions in the transition metal layers are removed on the first charge, leaving residual lithium ions in the lithium layers.