Tracer diffusion coefficients of lithium ion in LiMnO measured by neutron radiography

Takai, Shigeomi*; Yoshioka, Kazuya*; Iikura, Hiroshi  ; Matsubayashi, Masahito  ; Yao, Takeshi*; Esaka, Takao*

Lithiumisotope diffusion profiles in the cathodematerial LiMnO have been measured by using neutron radiography technique to determine the tracer diffusion coefficients in the temperature range of 300C to 800C. Arrhenius plot of the diffusion coefficient shows a bend around 550C. At the lower temperature region, the activation energy of the diffusion coefficient is obtained as 0.52 eV, which is essentially consistent with that of the reported NMR study. However, the extrapolated diffusion coefficient down to room temperature is considerably smaller than the chemical diffusion coefficients obtained by electrochemical methods. On the other hand, high temperature activation energy of 1.11 eV is relatively close to the previously investigated LiTiO, which also exhibits spinel-type structure and possesses the similar diffusion path via the 16c site. Within the present study, sintering temperature at the LiMnO sample preparation does not affect the tracer diffusion coefficient values.