Composition dependence of the energy barrier for lithium diffusion in amorphous WO3

Lithium insertion into amorphous WO3 films prepared by the electron beam evaporation technique was investigated by measurements of voltage-composition curve and chemical diffusion coefficient. The extraction of equilibrium and kinetic parameters allows the determination of the jump diffusion coefficient dependence on composition. In addition, first-principles calculations combining a pseudopotential plane wave scheme have been performed with the aim of providing a better understanding of the dependence of the potential barrier height for the hopping pathway with the insertion level for crystalline compounds. Our results predict a lowering of the barrier height for less doped systems and both experiments and simulations exhibit a relation of the type Delta E proportional to ck(B)T ln x for the composition range x < 0.3. (c) 2005 The Electrochemical Society.