Solid-state NMR Studies of Al-doped and Al2O3-coated LiCoO2

Abstract

As a cathode material for commercial lithium rechargeable battery, Al-doped and Al2O3-coated LiCoO2 were structurally characterized and compared by using solid-state 7Li and 27Al magic angle spinning (MAS) NMR. The structural states of lithium and aluminum in those samples were successfully identified by calculation of NMR spectra. 7Li MAS NMR spectra of samples had shown similar features having more than three lithium sites, which were determined as quadrupole coupling constant with the same asymmetric parameter (η = 0.1; CQ =1.10 MHz for octahedral site, and CQ = 2.97 MHz and CQ = 3.83 MHz for shoulders. 27Al MAS NMR spectra of samples, however, showed significant difference in two observed aluminum sites. In the simulation of NMR spectrum for Al2O3-coated LiCoO2, the values of CQ and η were obtained; 4.45 MHz and η = 0.86 for tetrahedral site and 4.31 MHz and η = 0.81 for octahedra. © 2004 Elsevier Ltd. All rights reserved.