INTERPRETATION OF POTENTIAL INTERMITTENCE TITRATION TECHNIQUE EXPERIMENTS FOR VARIOUS Li-INTERCALATION ELECTRODES

• Main Authors: M.D.Levi, D.Aurbach, M.A.Vorotyntsev
• Format: Article
• Language: English
• Published: Institute for Condensed Matter Physics 2002-01-01
• Series: Condensed Matter Physics
• Subjects: Li-ion battery; binary component; chemical diffusion coefficient; ionic conductivity; lattice gas model
• Online Access: http://dx.doi.org/10.5488/CMP.5.2.329

In this paper we compare two different approaches for the calculation of the enhancement factor W_i, based on its definition as the ratio of the chemical and the component diffusion coefficients for species in mixed-conduction electrodes, originated from the "dilute solution" or "lattice gas" models for the ion system. The former approach is only applicable for small changes of the ion concentration while the latter allows one to consider a broad range of intercalation levels. The component diffusion coefficient of lithium ions has been determined for a series of lithium intercalation anodes and cathodes. A new "enhancement factor" for the ion transport has been defined and its relations to the intercalation capacitance and the intercalation isotherm have been established. A correlation between the dependences of the differential capacitance and the partial ion conductivity on the potential has been observed. It is considered as a prove that the intercalation process is controlled by the availability of sites for Li-ion insertion rather than by the concurrent insertion of the counter-balancing electronic species.