Tracer diffusion coefficients of lithium ion in LiMn2O4 measured by neutron radiography

Lithium isotope diffusion profiles in the cathode material LiMn2O4 have been measured by using neutron radiography technique to determine the tracer diffusion coefficients D⁎ in the temperature range of 300 °C to 800 °C. Arrhenius plot of the diffusion coefficient shows a bend around 550 °C. 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 Li4Ti5O12, which also exhibits spinel-type structure and possesses the similar diffusion path via the 16c site. Within the present study, sintering temperature at the LiMn2O4 sample preparation does not affect the tracer diffusion coefficient values.