Self-Adaptive Re-Organization Enables Polythiophene as an Extraordinary Cathode Material for Aluminum-Ion Batteries with a Cycle Life of 100 000 Cycles.

Aluminum-ion batteries (AIBs) have attracted great attentions in recent years. Organic materials such as polythiophene (PT) are promising cathode for AIBs. However, the capacity and cyclic stability of conventional organic cathode such as PT are limited by the inadequate degree of reaction and the unstable nature of organic materials. To obtain high-performance organic cathode, a new PT with the ability of self-adaptive re-organization was prepared. During cycling, its molecular chain can be re-organized, and the polymerization mode will change from C α -C α (α-PT) to C β -C β (β-PT). This change leads to smaller steric hindrance and faster kinetics during ion insertion which can lower the reaction energy barrier and stabilize the molecular structure. Benefited by this, AIBs with this cathode can deliver a specific capacity of 180 mAh g -1 (@2 A g -1 ) and a superb stability of 100 000 cycles at 10 A g -1 . High energy density and power density can also be achieved with this cathode.