High-performance of quasi-solid-state complementary electrochromic devices based on Al³⁺/Li⁺ dual-ion electrolyte

Monovalent lithium ion has been successfully employed in quasi-solid-state electrochromic devices (ECDs), but it still needs to be optimized in terms of cost, life stability and so on. Herein, a novel electrolyte containing multivalent Aluminum ion (Al³⁺) was introduced into the ECDs and compared with Lithium ion ECDs. With acrylate-based UV curable glue as the gel electrolyte curing adhesive, WO₃ and NiO_x films as the complementary counter electrode layers, Li⁺ (ECD-1), Al³⁺ (ECD-2) and Al³⁺/Li⁺ double ion (ECD-3) as the electrolyte ions, three types of quasi-solid-state ECDs were prepared as Glass/ITO/WO₃/polymer electrolyte/NiO_x/ITO/Glass. The results showed that the optical modulation amplitude ΔT of three devices is 54.3%, 51.6%, and 53.2%, respectively, while the coloring efficiency (CE) is 62.2, 64.6, and 62.2 cm²/C. The cycle stability test results displayed that during 2000 CA cycles (lasting for 40,000 s, 20 s for one cycle), the optical modulation amplitude ΔT of the Al³⁺/Li⁺ devices only decays 16%, which has the excellent cycle durability compared with Li⁺ devices. This article is an effective attempt to expand the quasi-solid-state electrochromic electrolyte with multivalent ions species, which can broaden the application range of the devices.