Thermodynamics and Lithium Intercalation in CeO₂-TiO₂ Thin Film

Abstract

The kinetics and the thermodynamics of electrochemical intercalation of lithium into CeO₂-TiO₂ films prepared by the sol-gel process were studied by galvanostatic intermittent titration technique (GITT) as function of the depth of lithium intercalation. The open-circuit-potential versus x in Li_x(CeO₂-TiO₂) curve consists of two straight lines with different slopes, one in the range of 0.03 ≤ x ≤ 0.09 and the other of 0.09 < x ≤ 0.15. The standard Gibbs energy for lithium intercalation was 6 kJ/mol for x = 0.09 in Li_x(CeO₂-TiO₂) at room temperature. The chemical diffusion coefficient value, D _{Li ⁺} , of lithium intercalation into thin film oxide was 2.14·10⁻¹¹ cm²/s at x = 0.15, and the value of the component diffusion coefficient D _{Li ⁺, k} was about one order of magnitude lower than the coefficient of chemical diffusion.

Keywords:

• Cerium-titanium oxide
• kinetics
• sol-gel process
• thermodynamics

Acknowledgments

The authors would like to acknowledge the Brazilian agencies FAPESP, CNPq, and CAPES for the financial support given to this research.