Electrochromic smart window supercapacitor based on a hyperbranched electroactive polyamide for sustainable buildings

Abstract

Electrochromic smart windows (ESWs) possess the capability to markedly decrease energy usage in buildings by actively regulating solar radiation, thereby aiding in the advancement of sustainable architecture. Throughout the cyclical processes of coloring and bleaching, these windows demonstrate a one-way energy consumption pattern, allowing them to operate as energy storage systems that can supply power to a range of electrical devices. Consequently, there is a strong impetus to merge solar radiation modulation with energy recovery, resulting in next-generation smart windows that are not only more efficient in energy conservation but also enhance overall performance and sustainability. In this context, we introduced a hyperbranched electroactive polyamide that offers advantageous processability along with dual-band solar modulation capabilities. When paired with a zinc frame counter electrode, we developed an innovative smart window supercapacitor (SWSC) that demonstrates remarkable electrochromic properties (ΔT > 59.51 % and optical bistability) and commendable energy storage characteristics (voltage range of 2.4 V and specific capacitance of 85.76 mF/cm²). Energy simulations indicated that employing the SWSC to manage the indoor climate resulted in an average annual energy savings of 339.05 MJ/m², which represents approximately 19.00 % of the building’s total energy usage. Furthermore, over 73.00 % of the electrical energy required for the color transition in the SWSC can be reclaimed through a sophisticated convertible circuit to power small household appliances.