Li+ ionic diffusion in LiCoO2 exposed to ball milling was studied by XRD,

complex resistivity, and NMR. Angular frequency dependence of the complex

resistivity was analyzed by using a Debye-type relaxation model. The Li+ ion

hopping time becomes fast by exposing to short-time milling, whereas it becomes

slow by exposing to long-time milling. The activation energy of the Li+ ionic

diffusion in milled LiCoO2 samples varies from 0.29 to 0.36eV as the milling time

increases up to 60h. These results suggested that exposure to appropriate milling

time enhances the Li+ ionic diffusion but the excessive milling was

disadvantageous for the Li+ ionic diffusion. In addition, an increase in the line

width of 7Li NMR spectrum with increasing milling time was discussed in

connection with the line width arising from magnetic cobalt ions.

Lithium Ionic Diffusion in Lithium Cobalt Oxides Prepared by Mechanical Milling.

K.Nakamura, H.Hirano, D.Nishioka, Y.Michihiro, T.Moriga: Solid State Ionics,

2008, 179[27-32], 1806-9