Tunable Properties of Mg-Doped V 2 O 5 Thin Films for Energy Applications: Li-Ion Batteries and Electrochromics

Vanadium pentoxide (V 2 O 5 ) is doped for the first time with Mg, and the influence of Mg content on the films properties and functionality is investigated in detail, emphasis given on the electrochemical and electrochromic response. The Mg-doped V 2 O 5 films exhibit characteristics suitable for lithium ion batteries and electrochromic window applications, the optimization of the functionality depending on the Mg content. Low Mg content (2 at. % Mg) appears to favor lithium ion battery applications, the corresponding films exhibiting high specific discharge capacity, increased diffusion coefficient, and high capacity retention. In contrast, high Mg content (15 at. % Mg) is more favorable for electrochromic windows, presenting fast switching response time, high coloration efficiency, and high visible transmittance. In both cases, the determined characteristics are superior or at least equivalent to those reported for V 2 O 5 doped with other transition metals. The obtained results clearly indicate that tuning of the Mg doping enables the growth of thin films with application-centered characteristics.