Metalorganic Quantum Dots and Their Graphene‐Like Derivative Porous Graphitic Carbon for Advanced Lithium‐Ion Hybrid Supercapacitor

Abstract Lithium‐ion hybrid supercapacitors (LICs) are considered as a promising candidate in energy storage systems. Taking the factor of sluggish kinetics behavior, battery‐type anode plays a significant role in improving the performance of LICs. Here, onion‐shaped graphene‐like derivatives are synthesized via carbonization of metalorganic quantum dots (MQDs) accompanied with in situ catalytic graphitization by reduced metal. Notably MQDs, exhibiting water‐soluble character and ultrafine particles (2.5–5.5 nm) morphology, are prepared by the amidation reaction. The carbonized sample exhibits highly graphitic tendency with graphitization degree up to 95.6%, and shows graphene‐like porous structure, appropriate amorphous carbon decoration characteristic, as well as N‐doping and defective nature. When employed as anode material in LICs, it shows high energy density of 83.7 Wh kg –1 and high power density of 6527 W kg –1 when the mass ratio of cathode to anode is 1:1 and the operating voltage ranges from 2.0 to 4.0 V. It also possesses the long cyclic stability with the energy density retention maintains at 97.3% after 10 000 cycles at 5.0 A g –1 . In addition, the energy density is further increased by altering cathode/anode mass ratio and extending working voltage. This work provides a novel strategy to develop unique carbon materials for energy storage.