A tough and high adhesive ionogel electrolyte achieved by in situ phase separation for high-performance electrochromic devices†

Abstract

Ionogels are promising candidates for electrolytes used in electrochromic devices (ECDs) attributed to their good thermal stability, low saturation vapour pressure and high ionic conductivity. However, the poor mechanical and adhesive strength of electrolytes in these devices limits their practical applications in daily life. Here, an ionogel electrolyte with high mechanical properties and adhesive strength was prepared by a simple and efficient one-step polymerization method using an in situ phase separation strategy. The ionogel possesses high toughness (5.33 MJ m⁻³) and stretchability (786%) as well as high adhesive strength (2.18 MPa) and excellent peel resistance. We assembled ECDs using this excellent ionogel as an electrolyte, along with poly(3,4-(2,2-dimethyl-propanedioxy)thiophene) (PProDOT-Me₂) film and prussian blue (PB) film as the electrochromic layer and the ionic storage layer. It demonstrated significant transmittance contrast (50%), rapid response time (1.2/1.8 s), and exceptional cycling stability, maintaining over 95% of its performance after 10 000 cycles. This ionogel electrolyte with high mechanical properties and high adhesive strength will further promote the practical application of ECDs.