Electrochemical determination of the lithium ion diffusion coefficient in TiS 2

Abstract

Long-time chronoamperometry of TiS 2 electrodes immersed in saturated LiClO 4/DMF solution was employed to investigate the charge transport processes which govern the rate of Li + intercalation in TiS 2. The intercalation rate and hence, the current, appears to be controlled by the rate of Li + diffusion within the TiS 2. A model has been developed which predicts the current-time behavior under the control of Li + solid state diffusion. The close agreement of this model with the experimental data allows the solid state diffusion coefficient and other transport parameters (such as effective electrode area) to be evaluated from the measured average grain boundary distance. Typical TiS 2 grain boundary distances in the 3–10 μm range yield a geometric mean value of 1.3 × 10 −9 cm 2/s for the solid state diffusion coefficient; this is in close agreement with previously reported diffusivities as measured by NMR spin-lattice relaxation techniques.