Structural study of NiO2 and CoO2 as end members of the lithiated compounds by in situ high resolution X-ray powder diffraction

In-situ X-ray diffraction has been carried out on LixNiO2 and LixCoO2 batteries, using the high resolution powder diffractometer BM16 at ESRF (Grenoble, France). Diffraction was performed in transmission geometry through 1-mm thick Bellcore-type plastic batteries. The batteries were controlled in potentiostatic mode. During these experiments, end-members NiO2 and CoO2 have been isolated, and high resolution patterns have been recorded in order to solve their structures from powder data. NiO2 structure is of CdI2 type, with a monoclinic distortion. CoO2 seems to be of CdCl2 type also with a monoclinic distortion.