This paper presents a high-stability, single-phase hybrid polyelectrolyte (SPHP) applied in a large EC device (5×10 cm2) using WO3(electrochromic) and CeO2-TiO2(counter-electrode-ion storage) electrodes, both produced by Leibniz-Institut of New Materials (Leibniz-INM, Germany). The electrochromic device exhibited excellent color and bleach reversibility, high coloration efficiency (>35 cm2/C) from the first cycle up to more than 60,000 CA cycles, and a maximum constant rate of deintercalation/intercalation (Oout/Qin=1). Its remarkable behavior and high stability render this material an excellent candidate for application in electrochromic devices.