Mixed Ionic‐Electronic Conducting Polymer Enables Efficient Electrochromic Supercapacitor

Abstract Electrochromic energy storage devices have emerged as promising multifunctional platforms that integrate optical modulation with energy storage capabilities. However, their advancement is significantly impeded by sluggish reaction kinetics caused by inherent concentration polarization originating from mismatched ionic and electronic transport mechanisms, as well as resistance to solid‐state diffusion. Herein, an organic mixed ion/electron‐conducting polymer is proposed comprising an oligoaniline backbone bearing covalently tethered imidazole termini. The mixed polymer molecular design combines a conjugated segment for charge transport and the polyelectrolyte species for ion transport, allowing for effective charge redistribution as well as fast electron/ion conduction in a single material. The fabricated electrochromic supercapacitor demonstrates transmittance modulations of 58.14% (T VIS ) and 49.91% (T NIR ), a high areal capacity of 114.32 mF cm −2 , and remarkable capacity retention of 91.78% after 10 000 cycles. Notably, integrating the electrochromic supercapacitor with a multifunctional control system results in excellent light/thermal management characteristics within the solar radiation spectrum range, leading to an ideal energy saving of 300.07 MJ m −2 per year. The novel molecular design of the mixed conducting polymer, combined with the insights into the two conduction modes, offers a promising platform for designing next‐generation smart windows.