Engineering Low Lattice Mismatch Interface Layer for Durable and Bi-stable Dynamic Smart Windows Based on Reversible Metal Electrodeposition

Abstract

Reversible metal electrodeposition-based electrochromic devices (RMEDs) featuring large optical contrast, broadband optical modulation, simple device configuration and color neutrality have emerged as promising dynamic window platforms for advancing building energy efficiency. However, achieving long-term durability and bi-stability remains challenging due to the uncontrolled electrode/electrolyte interface structure. Herein, we screen and graft a low lattice mismatch (δ) NiO@C layer onto fluorine-doped tin oxide (FTO) glass, offering homogeneous interfacial electric field/ ion concentration/ current density distributions and higher interface Zn (002) formation energy (Ef = -0.449 eV•atom -1 ) to guide uniform Zn-Cu codeposition. The low δ NiO@C-FTO demonstrates lower metal plating/stripping activation energy (7.32 KJ•mol -1 ), large optical modulation (ΔT = 65.1%), fast switching (tc = 10.2 s, tb = 7.2 s), high coloration efficiency (16.77 cm 2 •C -1 ), color neutrality (Chroma C* = 3.585), and outstanding stability (> 3100 cycles). The as-assembled NiO@C-RMED demonstrates exceptional bi-stability (T% < 10% after 22 days), excellent heat blocking capability, large solar heat gain coefficient modulation (0.38), and remarkable building energy-saving potential in either tropical (annual energy savings up to 185 MJ•m -2 vs. Low-e glass) or other climatic zones. This work sheds light on electrode/electrolyte interface engineering towards durable and bi-stable electrochromic smart windows for advancing building energy efficiency.