A Crystalline, 2D Polyarylimide Cathode for Ultrastable and Ultrafast Li Storage.

Organic electrode materials are of long-standing interest for next-generation sustainable lithium-ion batteries (LIBs). As a promising cathode candidate, imide compounds have attracted extensive attention due to their low cost, high theoretical capacity, high working voltage, and fast redox reaction. However, the redox active site utilization of imide electrodes remains challenging for them to fulfill their potential applications. Herein, the synthesis of a highly stable, crystalline 2D polyarylimide (2D-PAI) integrated with carbon nanotube (CNT) is demonstrated for the use as cathode material in LIBs. The synthesized polyarylimide hybrid (2D-PAI@CNT) is featured with abundant π-conjugated redox-active naphthalene diimide units, a robust cyclic imide linkage, high surface area, and well-defined accessible pores, which render the efficient utilization of redox active sites (82.9%), excellent structural stability, and fast ion diffusion. As a consequence, high rate capability and ultrastable cycle stability (100% capacity retention after 8000 cycles) are achieved in the 2D-PAI@CNT cathode, which far exceeds the state-of-the-art polyimide electrodes. This work may inspire the development of novel organic electrodes for sustainable and durable rechargeable batteries.