Structure optimized pyrenetetraone composites for long-life high-energy Al-ion batteries

The development of organic cathodes is crucial for the development of high-capacity rechargeable Al-ion batteries, in which the molecular dissolution of the organic active materials is a key factor hindering practical application. Based on Pyrene 4,5,9,10 tetraone (PTO) cathodes, we demonstrated that the energy storage mechanism involves the incorporation of chloroaluminate into PTO to generate divalent [PTO-2AlCl2]2- ions, while the dissolution of the resultant anions in the electrolyte significantly degrades the capacity retention. Once the electrochemical species conversion and the mechanism of capacity fading are understood, we develop a facile method to in-situ weave polyaniline nanocoating on PTO-GO nano-particles to suppress the dissolution while facilitating conductivity. This design results in a high energy density of 423 Wh kg- 1 and significantly improved capacity retention. This study sheds light on the structure-stability relationship of organic materials and broads an avenue for cathode design of Al-ion batteries.