Aqueous zinc (Zn) metal electrodeposition-based electrochromic windows (AZWs) are a promising dynamic window technology due to their use of low-cost, nonflammable, nontoxic, and highly conductive aqueous electrolytes. However, their development is hindered by issues such as poor reversibility, byproduct formation, and hydrogen evolution, which limit the optical window and cycling lifespan. Herein, a bionic transparent nanogel interlayer (TGI) in triple-layer structure introduced on both Zn electrode and indium tin oxide (ITO) glass electrode is demonstrated to achieve highly reversible electrochemical reaction. In the spontaneously formed triple-layer nanogel architecture, the top hydrophobic protective layer effectively mitigates water corrosion and suppresses hydrogen evolution reactions as well as byproduct formation. The middle layer incorporates internal fluorinated functional groups to promote uniform and rapid Zn ion transport. The bottom colloidal adhesion layer dynamically adapts to the substrate surface, preventing detachment due to morphology changes during cyclic Zn deposition/stripping processes. Consequently, the AZWs incorporating TGI@Zn and TGI@ITO glass electrodes exhibit excellent electrochemical properties and solar heat modulation abilities, which are attributed to their enhanced reversibility and uniform deposition of Zn ions. Compared with the single-layer interlayer, the three-layer structure design significantly improves the electrode's stability and performance, providing new ideas for designing next-generation AZW electrodes.
Wang et al. (2025) studied this question.