A hair-trigger self-powered electrochromic window and a rechargeable battery ignoring charging process

Self-powered electrochromic windows (ECWs) have become an appealing research hotspot for their multifunctionality and energy efficiency without external voltage supplies. Many previous researches that utilized active metals, solar cells and nanogenerators to realize self-powered ECWs were baroque or inefficient. In this work, we propose a tri-layered electrochromic (EC) window comprising multifunctional hydrogel, EC material and current collector to realize controllable self-coloration and self-bleaching processes of the ECW by introducing a magnesium (Mg) anode and an ammonium persulfate (AP) cathode, which also serve as secondary batteries ignoring charging processes via reverse electrons migration between Mg/EC and AP/EC circuits. This unique architecture yields remarkable electrochemical performances, including rapid self-coloration time (0.5 s) and self-bleaching time (1.9 s), a high optical contrast (∼51%), long cycling durability (99.12% optical contrast remains after ∼1500 cycles when driven by electricity supply), and lighting a 1.8 V red LED up for 2 h. In addition, we also established a 10 × 10 cm2 prototype device as the suitability demonstration for large-area ECWs. This newly proposed configuration offers opportunity for multifunctional self-powered ECWs, and will possibly accelerate the development of environment-friendly and energy-saving appliances.