The preparation of solid solutions of the LiAlO2−LiCoO2 system in the complete composition range is described. Powder X-ray diffraction gives direct information about the partial substitution of Co by Al atoms, together with a fractional occupancy of tetracoordinated sites by aluminum atoms. EPR of impurity Ni3+ ions and 6Li and 27Al MAS NMR spectroscopies are used to assess for cation distribution. 6Li NMR spectra show a single resonance of lithium ions in octahedral sites. 27Al NMR spectra show that the distribution of Al atoms in tetrahedral and octahedral sites changes with composition. EPR spectra evidence that Ni3+ impurity ions in the Al y Co1 - y O2 layers prefer mainly Al3+ ions as first neighbors. The potential applicability of these materials as intercalation electrodes is also evaluated in lithium anode cells. A poor lithium ion diffusivity, resulting from the presence of aluminum in both tetrahedral and octahedral sites, may limit the applicability of LiAl y Co1 - y O2 cathodes. The partial substitution of Co by Ni leads to an improvement of the electrochemical performance.

structure structure (solids and liquids) D 2000 -001X-Ray Diffraction, EPR, and 6 Li and 27 Al MAS NMR Study of LiAlO 2 -LiCoO 2 Solid Solutions.-Solid solutions are prepared over the complete composition range. Powder XRD patterns are all indexable in the rhombohedral LiCoO 2 or α-LiAlO 2 structures (e.g. LiAl 0.2 Co 0.08 O 2 : space group Rr3rm, Z = 3). The 6 Li NMR spectra show a single resonance of Li + in octahedral sites. The 27 Al NMR spectra show that the distribution of Al 3+ over tetrahedral and octahedral sites changes with composition. The potential applicability of these materials as intercalation electrodes is also evaluated in Li anode cells. The partial substitution of Co by Ni leads to improved electrochemical performance. -(ALCANTARA, R.; LAVELA, P.; RELANO, P. L.; TIRADO, J. L.; ZHECHEVA, E.; STOYANOVA, R.; Inorg.