Conjugated porous polyimide poly(2,6-diaminoanthraquinone) benzamide with good stability and high-performance as a cathode for sodium ion batteries

Organic electrode materials with environmental friendliness and design flexibility at the molecular level are promising substitutes for inorganic materials as cathodes for sodium ion batteries (SIBs). However, traditional organic electrode materials usually exhibit poor cycling stability, mainly due to the dissolution of small organic molecules in electrolytes, and low electronic conductivity. Herein, conjugated porous polyimide poly(2,6-diaminoanthraquinone) benzamide (CP-PDAB) was prepared from 2,6-diaminoanthraquinone and pyromellitic dianhydride by a simple polycondensation reaction. The obtained CP-PDAB has disordered aggregates with a porous and loose structure, facilitating the penetration of the electrolyte and buffering the volume change during charging/discharging. The conjugated skeleton with electron delocalization offers the benefits of structural stability, insolubility in electrolyte and high electronic conductivity. When evaluated as a cathode for SIBs, it can retain a high reversible discharge capacity of 141 mA h g(-1) at 500 mA g(-1) for 100 cycles, and can maintain a high specific capacity of 71 mA h g(-1) at 10 A g(-1) after 500 cycles. This work demonstrates the potential application of organic materials containing a conjugated skeleton, porous and loose structure for next-generation electrochemical energy storage devices.