Boosting Lithium Storage Performance of Small-Molecule Organic Cathodes through Synergistic Molecular Engineering and...

Small-molecule organic carbonyl compounds (SMOCCs) featuring high theoretical capacities are promising cathodes for lithium-ion batteries (LIBs), but facing challenges in cycling stability and rate performance owing to their high solubility in organic electrolytes and low conductivity. Herein, we propose a novel architecture wherein nanosized SMOCCs with N-heterocycle-extended π-conjugation are uniformly immobilized on reduced graphene oxide (rGO). This approach leverages the N-heterocycles to create additional active sites and strengthen π-π interactions with rGO, while the homogeneous distribution of nanosized SMOCCs on rGO facilitates efficient charge transport and electrolyte infiltration. As a demonstration, we synthesize a composite material using dipyrido[3',2':5,6;2'',3'':7,8]quinoxalino[2,3-i]dipyrido[3,2-a:2',3'-c] phenazine-10,21-dione (DQDPD) as the active component, which exhibits remarkable electrochemical properties in LIBs, including an ultrahigh capacity of 505 mAh g^-1 at 0.2 A g^-1, exceptional cycle stability with 82 % capacity retention after 3000 cycles at 5 A g^-1, and outstanding rate capability of 290 mAh g^-1 at 10 A g^-1. Our approach, which integrates molecular engineering and nanostructure design, provides a novel paradigm for simultaneously realizing high capacity, long lifespan, and rapid rate capability in SMOCCs.