Cross-linked polyaniline for production of long lifespan aqueous iron||organic batteries with electrochromic properties
Haiming Lv, Zhiquan Wei, Cuiping Han, Xiaolong Yang, Zijie Tang, Yantu Zhang, Chunyi Zhi, Hongfei Li
Abstract
Abstract Aqueous iron batteries are appealing candidates for large-scale energy storage due to their safety and low-cost aspects. However, the development of aqueous Fe batteries is hindered by their inadequate long-term cycling stability. Here, we propose the synthesis and application as positive electrode active material of cross-linked polyaniline (C-PANI). We use melamine as the crosslinker to improve the electronical conductivity and electrochemical stability of the C-PANI. Indeed, when the C-PANI is tested in combination with a Fe metal negative electrode and 1 M iron trifluoromethanesulfonate (Fe(TOF) 2 ) electrolyte solution, the coin cell can deliver a specific capacity of about 110 mAh g −1 and an average discharge voltage of 0.55 V after 39,000 cycles at 25 A g −1 with a test temperature of 28 °C ± 1 °C. Furthermore, mechanistic studies suggest that Fe 2+ ions are bonded to TOF − anions to form positively charged complexes Fe(TOF) + , which are stored with protons in the C-PANI electrode structures. Finally, we also demonstrate the use of C-PANI in combination with a polymeric hydrogel electrolyte to produce a flexible reflective electrochromic lab-scale iron battery prototype.