Effect of interactions between lithium ions on lithium intercalation into and deintercalation from the $Li[Ti_{5/3}Li_{1/3}]O_4$ film electrode

Abstract

The effect of the interactions between lithium ions on the lithium intercalation into the Li[Ti513Li113]O4 film electrode was investigated from the thermodynamic and kinetic view points by using Monte Carlo simulation. For the purpose, the electrode potential vs. lithium content curve was measured on the film electrode, and the ac-impedance spectra were obtained from the film electrode as a function of lithium content. In addition, the potentiostatic current transients were measured on the film electrode at various applied potential steps. The results experimentally measured were then compared with those results theoretically calculated in consideration of the interactions between lithium ions by using Monte Carlo simulation. The electrode potential vs. lithium content curve measured on the Li[Ti513Li16]O4 film electrode showed a wide potential plateau at 1.56 VLiIL+. In consideration of the repulsive interactions between lithium ions by using Monte Carlo method, the electrode potential was theoretically calculated as a function of lithium content. The electrode potential curve theoretically calculated was in good agreement with that curve experimentally measured. With the aid of the local cross-sectional snapshot of the configuration of lithium ions in the electrode, it was suggested that the wide potential plateau in the electrode potential curve indicates the coexistence of a lithium-diluted phase a and a lithium-concentrated phase /3 due to the repulsive interactions between lithium ions. The ac-impedance spectra of the film electrode consisted of two separated arcs in the high and intermediate frequency range, a straight line inclined at constant angle to the real axis (Warburg region), and a capacitive line (blocking region) in the low frequency range. From the analysis of the ac-impedance spectra measured on the film electrode, it was found that the resistance determined from the second arc related to the absorption-desorption of lithium ions at the elec...