A Local-Dissociation Solid-State Polymer Electrolyte with Enhanced Li+ Transport for High-Performance Dual-Band Electrochromic Smart Windows

Windows through heat exchange play a vital role in energy saving for realizing a net-zero carbon emission society. Dual-band electrochromic (EC) smart windows by dynamically regulate visible (VIS) and near-infrared (NIR) light are necessary for improving both building energy efficiency and habitant comfort. However, the rational design of high-performance electrochromic devices (ECDs) suffers sluggish EC response due to the slow ion transport. In this work, a locally dissociated Li + concept is proposed to construct a solid-state polymer electrolyte (SPE) with ultrafast Li + transport. The succinonitrile (SN) is employed to loosen the Li + -anion pair and the crystallographic C─O chain in the poly(ethylene glycol) methyl ether methacrylate (PEGMA) electrolyte by its strong solvation capability. The as-prepared SPE shows a high ionic conductivity of 6.48 mS cm −1 at 30 °C and a high transmittance of >90%. The SPE-based EC smart windows exhibited a fast switching speed (3.0/3.2 s for coloration/bleaching), a high coloration efficiency (CE) of 373.8 cm 2 C −1 , and a high optical modulation in the full solar spectrum (85%, 70%, 43% at 673, 1200, and 1600 nm, respectively). Finally, the SPE-based EC smart windows shows three working modes with a temperature regulation range of 19.1 °C, exhibiting great potential in practical application.