Structural Relaxation of Li x (Ni 0.874 Co 0.090 Al 0.036 )O₂ after Lithium Extraction down to x = 0.12.

A structural relaxation study has been carried out on Li _x (Ni _0.874 Co _0.090 Al _0.036 )O₂ after the electrochemical lithium was extraction down to x = 0.12. These relaxation analyses have been carried out using X-ray diffraction coupled with the Rietveld analysis, assuming two phases (H2 and H3) and co-existence with R3¯m symmetry. The mole fraction of the H3 phase seemed not to vary largely during the relaxation time. As for the lattice constants, both H2 and H3 phases gradually increased the a -axis with the relaxation time. On the other hand, H2 and H3 phases increased and decreased the c -axis, respectively. The results are compared with that of previously reported Ni-rich NCA.