In Situ X-Ray Diffraction Study of P2-Na[sub 2/3][Ni[sub 1/3]Mn[sub 2/3]]O[sub 2]

The electrochemical extraction and insertion of Na in was studied by in situ X-ray diffraction. All the original Na can be extracted from and it can be reversibly inserted again. When in the compound remains in the P2 structure. For a small amount of O2-type stacking faults are introduced into the structure. When the electrode exists as two coexisting phases. These are (with some O2-type stacking faults) and adopts the O2 structure with stacking...