6LI and 7Li MAs NMR and in situ x-ray diffraction stuides of lithium manganate cathode materials

摘要

6Li MAS NMR spectra of lithium manganese oxides with differing manganese oxidation states are presented. Improved undestnding of ht lithium NMR spectra of these model compounds is used ot interpret the local structure of the LI_xMn_2O_4 cathode materials following electrochemical Li~+ deintercalation to various charging levels. In situ x-ray diffraction patterns of the same material during charging are also reported for comparison. Evidence for two-phase behvior for x<0.4 is seen by both NMR and diffraction.