Self-Rechargeable Aqueous Zn2+/K+ Electrochromic Energy Storage Device via Scalable Spray-Coating Integrated with Marangoni Flow

Abstract

Electrochromic batteries (ECBs) represent a novel integration of energy storage and optical modulation technologies, offering versatile applications from smart windows to portable electronics. This work explores the potential of zinc-ion (Zn²⁺) electrochromic batteries utilizing tungsten trioxide (WO₃) as an active material. To address research gaps, the study focuses on coating techniques and hybrid ion electrolytes to enhance performance and sustainability. Spray coating with ethanol solvent demonstrates superior uniformity and film quality compared to de-ionized water, attributed to Marangoni flow effects. Moreover, hybrid Zn-K electrolytes show enhanced electrochromic and electrochemical performance, offering higher ΔT (50%) modulation and cyclic stability (10000 s). Theoretical analysis confirms the favorable interaction of K⁺ ions with WO₃. Prototype ECB devices exhibit exceptional cyclic stability (3000 cycles), rapid self-charging capabilities (10 min), and reversible optical modulation (40%), showcasing the potential for sustainable energy storage solutions in smart electronics.