Polyimide/metal-organic framework hybrid for high performance Al - Organic battery

Aluminum(Al)-organic batteries are considered as a great alternative option for next generation energy storage devices. The recent Al-organic batteries propose new storage mechanisms of cationic aluminum complex ([AlClx]3−x, x ​= ​1 or 2) distinguished from traditional AlCl4−, represent an important breakthrough for aluminum batteries. However, the electrochemical storage mechanisms (value of x in [AlClx]3−x) are related to different types of organic materials, the poor cycling stability caused by inevitable dissolution of organic materials in electrolyte, and the complex synthetic process restrict the development of Al-organic batteries. Herein, polyimide (PI)/metal-organic frameworks (MOFs) hybrid material synthesizing from a facile one-pot strategy as cathode material in Al-organic battery is reported, providing with high specific capacity and excellent cycle stability. The PI/MOFs hybrid electrode achieves capacity of 83 ​mA ​h ​g−1 ​at 1000 ​mA ​g−1 with high coulombic efficiency (almost 100%). It also exhibits an excellent cycle performance of 1800 cycles with only a capacity decay of 0.0067% per cycle. Furthermore, the electrochemical storage mechanism of PI/MOFs is evaluated by ex-situ X-ray photoelectron spectroscopy and energy dispersive X-ray spectrum, which demonstrate that the cationic chloroaluminates interact with reduced carbonyl bonds in PI during discharge is AlCl2+. These findings are of great significance for the basic understanding of the working mechanism of PI compound cathode in Al-organic batteries, which may serve as a solid foundation for further development of novel organic cathode materials and their composites for Al-organic batteries.