<p>V₂O₅ films with high ion storage capacity (Q) and wide optical modulation range (∆T) have great potential for application in electrochromic devices. In this paper, Ni-La-V₂O₅ porous ion storage films are prepared by the sol–gel method. The effects of Ni-La co-doping content, PEG content, and heat treatment temperature on the properties of V₂O₅ films were investigated. By comparison, it was found that the Q value of 9 mol% Ni-5.5 mol% La-V₂O₅ film was increased compared to 9 mol% Ni-V₂O₅ film, but ∆T was decreased. In order to improve ∆T, Ni-La-V₂O₅ porous ion storage films were prepared using Ni-La co-doping and PEG pore-former, and the optimization of process parameters was carried out via Response Surface Methodology (RSM). The RSM results showed that the influence on the Q value was in the following order: heat treatment temperature &gt; Ni-La co-doping content &gt; PEG content. Under the near-optimal process parameters, a satisfying V₂O₅ film with a high Q value (120.23 mC/cm²), a good ∆T (79.8%), and a short response time (3.1 s/2.8 s) were obtained, which further demonstrated the superior electrochromic performance.</p> Graphical Abstract <p></p>