Interpretation of variations of jump diffusion coefficient of lithium intercalated into amorphous WO3 electrochromic films

We report a series of electrochemical analysis of homogeneous a-LixWO3 films of 400 nm thickness prepared by electron beam evaporation technique. Self-diffusion coefficient DJ was analyzed combining measurements of the chemical capacitance, Cch, and chemical diffusion coefficient, Dch, concluding that the barrier height involved in ion hopping increases ∼150 meV within the range of lithium insertion level 0.001<x<0.3. The observed dependences Cch∝xa (a≈0.65) and DJ∝x−c (c≈1.25) suggest that the energy changes governing charge storage and hopping are predominantly determined by the interaction energy of intercalant ions with the host glass.