A Unique Structure of Ni(III) in LiNi0.3Co0.7O2 Without Jahn-Teller Distortion

A. N. Mansour (1) , Laurence Croguennec (2) , Claude Delmas (2)

1 Carderock Division
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

We examined the oxidation state and atomic structures of Ni and Co in LiNi0.3Co0.7O2 and compared them with those of LiNiO2 and LiCoO2. The X-ray absorption near-edge structure and extended X-ray absorption fine structure results show that Ni (primarily) and Co are present with an oxidation state of +3. Ni(III) in LiNiO2 has a distorted octahedral coordination due to an active Jahn-Teller effect as shown previously. However, Ni(III) in LiNi0.3Co0.7O2 has a regular octahedral coordination with six oxygen atoms at a distance of 1.913 Å and, hence, the Jahn-Teller effect is inactive. The oxidation state and local atomic structure of Co in LiNi0.3Co0.7O2 are similar to those of LiCoO2.

Mots clés: x-ray absorption; Secondary lithium cells; Fine structure analysis; Electrochemical properties; Electrode materials; Cathode materials; LiNiO2; LiCoO2; EXAFS

Domaines: Matériaux

A. N. Mansour, Laurence Croguennec, Claude Delmas. A Unique Structure of Ni(III) in LiNi0.3Co0.7O2 Without Jahn-Teller Distortion. Electrochemical and Solid-State Letters, 2005, 8 (10), pp.544-548. ⟨10.1149/1.2033621⟩. ⟨hal-00079049⟩