Transport of External Lithium Along Phase Boundary in LiF-Ti Nanocomposite Thin Films

Abstract

The electronic and ionic conductivity of the LiF-Ti nanocomposite films prepared by the co-sputtering have been investigated by the methods of impedance spectrum (IS), current-voltage curves (IV) and isothermal transient ionic current (ITIC) measurements. It is found that the ionic conductivity of the LiF-Ti nanocomposite film is very low. After electrochemical and chemical lithiation, ionic conductivities of the lithiated LiF-Ti composite films are increased to be 10-3 and 10-4 S/cm separately. This phenomenon indicates that the phase boundary between LiF and Ti should be the ionic conducting channels for external lithium in the LiF-Ti nanocomposite. Our results suggest a new strategy to design ionic or mixed ionic conductor.

Keywords

• LiF-Ti nanocomposite
• thin film
• lithiation
• external lithium
• ionic conductivity
• phase boundary