Boosting Lithium Storage in Graphene‐Sandwiched Cathodes Containing Multi‐Carbonyl Polyquinoneimine Nanosheets

Carbonyl polymers as booming electrode materials for lithium‐organic batteries are currently limited by low practical capacities and poor rate performance due to their inherent electronic insulation and microscopic agglomeration morphologies. Herein graphene/carbonyl‐enriched polyquinoneimine (PQI@Gr) composites were readily prepared by in  situ hydrothermal polycondensation of dianhydride and anthraquinone co‐monomer salts in the presence of graphene oxide (GO). Conductive graphene sheets derived from hydrothermal reduction of GO are fully sandwiched between densely interlaced quinone‐containing polyimide nanosheets. Remarkably, the as‐fabricated PQI@Gr cathodes exhibit much larger specific capacity (205 mAh g −1 at 0.1 A g −1 ), higher carbonyl utilization (up to 89.9%), and better rate capability (179.4 mAh g −1 at 5.0 A g −1 ) due to a surface‐dominated capacitive process via fast kinetics compared to bare PQI electrode (162.5 mAh g −1 at 0.1 A g −1 ; 67.5%; 96.9 mAh g −1 at 5 A g −1 ). The capacity retention as high as 73% for PQI@Gr is also achieved over ultra‐long 10 000 cycles at 5.0 A g −1 . Such outstanding electrochemical performances are attributable to the combined merits of polyimides and polyquinones, and robust 3D hierarchical heterostructures with efficient conductive networks, abundant porous channels for electrolyte infiltration and ion accessibility, and highly exposed carbonyl groups. This work offers new insights into the development of high‐performance polymer electrodes for sustainable batteries.