Can All the Lithium be Removed from T 2 ­ Li2 / 3 [ Ni1 / 3Mn2 / 3 ] O 2 ?

In this paper, it is demonstrated that all the lithium cannot be removed electrochemically from Li 2/3 [Ni 1/3 Mn 2/3 ]O 2 at room temperature below 5.4 V vs. Li/Li + . On the contrary, all the Na atoms can he extracted and reinserted reversibly from P2-Na 2/3 [Ni 1/3 Mn 2/3 ]O 2 electrochemically to form Na X [Ni 1/3 Mn 2/3 ]O 2 with 0 < x < 0.67. Both of these results have been confirmed by X-ray diffraction measurements. Furthermore, when all the Na is removed, □[Ni 1/3 Mn 2/3 ]O 2 adopts the 02 structure with random stacking faults. The diffraction pattern can be well matched by simulations of these stacking faults using the DIFFaX program. Lithium can be inserted into □[Ni 1/3 Mn 2/3 ]O 2 , however, only about one-half of the lithium which is inserted can be removed. X-ray diffraction shows that when the Li is inserted into □[Ni 1/3 Mn 2/3 ]O 2 , the structure transforms from O2 with stacking faults to 02 without stacking faults. We speculate upon the reasons for the difference between the behavior of Li and Na in this host system.

[1]  J. Dahn,et al.  Layered T2-, O6-, O2-, and P2-Type A2/3[M‘2+1/3M4+2/3]O2 Bronzes, A = Li, Na; M‘ = Ni, Mg; M = Mn, Ti , 2000 .

[2]  J. Dahn,et al.  O 2‐Type Li2 / 3 [ Ni1 / 3Mn2 / 3 ] O 2: A New Layered Cathode Material for Rechargeable Lithium Batteries II. Structure, Composition, and Properties , 2000 .

[3]  C. Delmas,et al.  NiO2 Obtained by Electrochemical Lithium Deintercalation from Lithium Nickelate: Structural Modifications , 2000 .

[4]  J. Dahn,et al.  O2 Structure Li2 / 3 [ Ni 1 / 3 Mn 2 / 3 ] O 2: A New Layered Cathode Material for Rechargeable Lithium Batteries. I. Electrochemical Properties , 2000 .

[5]  J. Dahn,et al.  Studies of the layered manganese bronzes, Na2/3[Mn1-xMx]O2 with M = Co, Ni, Li, and Li2/3[Mn1-xMx]O2 prepared by ion-exchange , 1999 .

[6]  J. Tarascon,et al.  In Situ Structural and Electrochemical Study of Ni1-xCoxO2 Metastable Oxides Prepared by Soft Chemistry , 1999 .

[7]  J. Dahn,et al.  Layered Li‐Mn‐Oxide with the O2 Structure: A Cathode Material for Li‐Ion Cells Which Does Not Convert to Spinel , 1999 .

[8]  D. A. Small,et al.  A Mossbauer effect investigation of the Li-Sn system , 1999 .

[9]  C. Angell,et al.  High Anodic Stability of a New Electrolyte Solvent: Unsymmetric Noncyclic Aliphatic Sulfone , 1998 .

[10]  J. Tarascon,et al.  CoO2, the end member of the LixCoO2 solid solution , 1996 .

[11]  M. Deem,et al.  A general recursion method for calculating diffracted intensities from crystals containing planar faults , 1991, Proceedings of the Royal Society of London. Series A: Mathematical and Physical Sciences.