Aromatic Polyimide/Graphene Composite Organic Cathodes for Fast and Sustainable Lithium-Ion Batteries.

A composite organic cathode material based on aromatic polyimide (PI) and highly conductive graphene was prepared through a facile in situ polymerization method for application in lithium-ion batteries. The in situ polymerization generated intimate contact between PI and electronically conductive graphene, resulting in conductive composites with highly reversible redox reactions and good structure stability. The synergistic effect between PI and graphene enabled not only a high reversible capacity of 232.6 mAh g-1 at a charge-discharge rate of C/10 but also exceptionally high-rate cycling stability, that is, a high capacity of 108.9 mAh g-1 at a very high charge-discharge rate of 50C with a capacity retention of 80 % after 1000 cycles. This improved electrochemical performance resulted from the combination of stable redox reversibility of PI and high electronic conductivity of the graphene additive. The graphene-based composite also exhibited much better performance than composites based on multi-walled carbon nanotubes and the conductive carbon black C45 in terms of specific capacity and long-term cycling stability under the same charge-discharge rates.