Carbonized cotton fiber supported flexible organic lithium ion battery cathodes

Conjugated microporous polyarylimides immobilization on carbon nanotubes with improved utilization of carbonyls as cathode materials for lithium/sodium-ion batteries

Aromatic polyimide (PI)-based compounds have been widely studied for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) due to their higher specific energy density, economical, environmentally friendly and adjustable redox potential window. However, their solubility in aprotic electrolytes, inherently poor conductivity and low active site utilization limit their application in large-scale energy storage system (ESS). Here, we synthesized two aromatic PI-based conjugated microporous polymers (CMPs) and integrated them with multi-walled carbon nanotubes (CNT) (TAPT-NTCDA@CNT and TAPT-PMDA@CNT) for using as cathode materials for LIBs and SIBs. The aromatic PI-based CMP can effectively utilize the redox activity site due to its abundant π-conjugated redox active units, stable imide bond, high specific surface area and clear pore structure. As expected, the optimum TAPT-NTCDA@CNT exhibits good rate performance (89.7 mAh g^-1 at 2000 mA g^-1) and long cycle stability (87.3% capacity retention after 500 cycles) in LIBs. Also, TAPT-NTCDA@CNT can provide a higher initial capacity of 91.1 mAh g^-1 in SIBs at 30 mA g^-1. This work provides key insights for the further development of other new organic electrodes for other advanced rechargeable batteries.