The development of hybrid electrolytes (HEs) that allows high mechanical properties and high ionic conductivity is a key in the smart mobility progress. In this article, various solid polymer electrolytes (SPEs) based on a blend of epoxy resins, ionic liquid, and titania or alumina nanoparticles have been manufactured and their electrochemical and thermomechanical performances have been evaluated. The combination of SPE components providing the highest properties was studied, having a significant influence on the type of nanoparticles and their dispersion. The electrolyte with the best combination of properties was L65P35(ILE)Al2, which showed T_g = 83 °C and E′ at 30 °C = 1.2 GPa as thermomechanical properties, and σ₀ = 7 × 10^–4 S/cm, σ₁ = 1.6 × 10^–6 S/cm, and C_sp = 5.6 × 10^–5 F/g at room temperature, as electrochemical properties. Moreover, the optimized electrolyte followed the Arrhenius ion transport model (E_a = 24.7 kJ/mol). These results would be promising for use as hybrid electrolyte in structural applications.