Intercalation of Water in P2, T2 and O2 Structure A_z[Co_xNi_1/3-xMn_2/3]O₂

The intercalation of water into P2-Na 2/3 [Co x Ni 1/3 - x Mn 2/3 ]O 2 ( x = 0, 1 / 6, 1 / 3 ) and T2 or O2 structure Li 2/3 [Co x Ni 1/3 - x Mn 2/3 ]O 2 ( x = 0, 1 / 6, 1 / 3 ) has been investigated by X-ray diffraction and thermogravimetric analysis (TGA). Water can be intercalated into P2-Na 2/3 [Co x Ni 1/3 - x Mn 2/3 ]O 2 ( x = 1 / 6, 1 / 3 ) but not within P2-Na 2/3 [Ni 1/3 Mn 2/3 ]O 2 . This difference may be related to the existence of superlattice ordering of Ni atoms, but not Co atoms, within the transition metal layer which apparently induces a very strong interlayer interaction and inhibits the uptake of water. Two water-containing phases of P2-Na 2/3 (H 2 O) y [Co 1/3 Mn 2/3 ]O 2 were found and one, with y ≈ 2/3, could be prepared in pure form. By Rietveld refinement of the X-ray diffraction pattern of P2-Na 2/3 (H 2 O) 2/3 [Co 1/3 Mn 2/3 ]O 2, it can be concluded that the compound still exists in the ideal P2 structure ( P 6 3 / mmc ) with the oxygen atoms of the water molecule located on the 2c site. Water cannot be intercalated into the corresponding lithiated phases, Li 2/3 [Co x Ni 1/3 - x Mn 2/3 ]O 2 for any value of x that we tested ( x = 0, 1 / 6, 1 / 3 ).