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

Abstract 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 cm² 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.