Water-in-eutectogel electrolytes for scalable solid-state electrochromic devices

Polymer electrolyte-based solid-state electrochromic (EC) devices hold great promise for commercial applications. However, existing polymer electrolytes suffer from persistent challenges, such as inadequate mechanical properties and poor electrode interface compatibility. Here, we introduce an innovative water-in-eutectogel (WIEG) electrolyte with dual-scale network, engineered with water molecules encapsulated within eutectic solvents and UV-cured hydrogen-bonded polymer networks. The WIEG electrolyte achieves wide electrochemical stability window, impressive mechanical strength and strong adhesion due to its hydrogen bond-rich network. Owing to the exceptional mechanical-electrochemical characteristics of the WIEG electrolyte, the integration of this electrolyte into a solid-state EC device exhibits an ultra-high cycling stability. Furthermore, the successful fabrication of patterned and large-scale EC devices underscores the versatility and scalability of this approach, positioning it as a breakthrough for applications in smart displays, energy-saving windows, and flexible electronics. This work presents a novel electrolyte design strategy for advancing high-performance EC devices.