The kinetics of lithium transport through vanadium pentoxide composite andfilm electrodes by current transient analysis

The kinetics of Lithium transport through vanadium pentoxide composite and film electrodes have been investigated in a 1 M solution of LiClO4 in propy lene carbonate using current transient technique. In the case of the vanadi um pentoxide composite electrode, all the cathodic and anodic current trans ients experimentally measured hardly followed the Cottrell behaviour and th e relation between initial current level in current transient and applied p otential step held Ohmic law. Lithium transport through the-composite elect rode was theoretically analysed by means of the numerical simulation of the current transient under the assumption of the ' cell-impedance controlled ' lithium transport. The current transients theoretically calculated shared quantitatively well those experimentally measured. In contrast, all the ca thodic and anodic current transients experimentally obtained from the film electrode, exhibited clearly a linear relationship between logarithmic curr ent and logarithmic time, followed by an exponential decay. From the result s, it is suggested that lithium transport through the film electrode procee ds under the ' diffusion controlled ' lithium transport towards rough (frac tal) interface. The difference in the mechanism of lithium transport betwee n through vanadium pentoxide composite electrode and through film electrode was discussed in terms of the chemical diffusivity of lithium ion and ' ce ll-impedance ' of the two electrodes. (C) 2001 Elsevier Science B.V. All ri ghts reserved.