Structural relaxation of Lix(Ni₀.₈₇₄Co₀.₀₉₀Al₀.₀₃₆)O₂ after Lithium Extraction down to x = 0.12

Abstract

A structural relaxation study has been carried out on Lix(Ni₀.₈₇₄Co₀.₀₉₀Al₀.₀₃₆)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 R3̅m 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.