Tough Hydrogen Bonding Crosslinked Poly(3-fluorothiophene) Network via Electrosynthesis for High-performance Electrochromic Supercapacitors

As a type of bi-functional device, electrochromic supercapacitors (EC-SCs) have attracted extensive attention in diverse applications such as flexible electronics. However, despite recent encouraging progress, rational design and development of high-performance EC-SC materials with desirable stability remain challenging for practical applications. Here, we propose a fluorination strategy to develop high-performance EC-SC materials with tough hydrogen bonding cross-linked intermolecular polymer network by one-step electrosynthesis of 3-fluorothiophene. The electrosynthesized free-standing poly(3-fluorothiophene) (PFT) films simultaneously achieve high electrochromic performance (optical contrast 42% at 560 nm with reversible color changes between purple and blue), and good capacitance property (290 F·g⁻¹, 1 A·g⁻¹), as well as outstanding cyclic stability (<2% reduction after 20000 cycles). We further demonstrate the fabrication of PFT-based flexible electrochromic supercapacitor devices (FESDs), and the resultant devices can be used to visually monitor the energy storage state in real-time and maintain outstanding stability under mechanical distortion like bending. Such a tough fluorination hydrogen bonding cross-linking strategy may provide a new design concept for high-performance EC-SC materials and reliable FESDs toward practical applications.