DFT modeling of NMR contact shift mechanism in the ideal LiNi2O4 spinel and application to thermally treated layered Li0.5NiO2

Cédric Chazel (1) , Michel Ménétrier (1) , Dany Carlier-Larregaray (1) , Laurence Croguennec (1) , Claude Delmas (1)

1 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux

LiNi2O4 spinel-type phases were prepared by thermal treatment of electrochemically deintercalated layered Li~0.5NiO2. The phase transformation was followed by 7Li NMR, showing a gradual change of the signal from the layered compound. The characteristic signal of the latter (related to local Li/vacancy and Ni3+/Ni4+ ordering) vanishes after heating to 150 C and is replaced by a new signal showing faster exchange kinetics (originating from Ni3+/Ni4+ hopping around Li), which progressively transforms into a broad distribution of signals. Around 200 C, a set of three positively shifted signals is observed, corresponding to the appearance of the spinel phase as seen from XRD; these signals disappear after heating to 240 C, corresponding to the beginning of decomposition of the spinel into a disordered Rm type phase with oxygen evolution as previously shown by Guilmard et al. (Chem. Mater. 2003, 15, 4476 and 4484)...

Mots clés: DFT; Spinel; Inorganic coumpounds; Layered compounds; Contact shift mechanism; LiNiO4

Domaines: Matériaux

Cédric Chazel, Michel Ménétrier, Dany Carlier-Larregaray, Laurence Croguennec, Claude Delmas. DFT modeling of NMR contact shift mechanism in the ideal LiNi2O4 spinel and application to thermally treated layered Li0.5NiO2. Chemistry of Materials, 2007, 19 (17), pp.4166-4173. ⟨10.1021/cm070324n⟩. ⟨hal-00179090⟩