Novel Doughnutlike Graphene Quantum Dot-Decorated Composites for High-Performance Li-S Batteries Displaying Dual Immobilization Toward Polysulfides

Emerging materials for high-performance Li-S batteries are of great significance. Here, we develop a unique doughnutlike graphene quantum dot (GQD)/Fe2O3@S@SnO2 composite for Li-S batteries. The GQDs are confined inside the yolk-shell structure, which could shorten the pathway for electron and ion transport, enhancing the utilization of sulfur and achieving an energy-storage performance. Both the Fe2O3 core and SnO2 shell display strong binding with Li2S4, Li2S6, and Li2S8, which is verified by using density functional theory calculations. The doughnutlike GQD/Fe2O3@S@SnO2-based Li-S battery displays a capacity of 923 mAh g(-1) after cycling 100 times, an approximate to 100% Coulombic efficiency, and a recoverable rate performance after repeated measurements. The constructed battery possesses a good tolerance at a high temperature of 45 degrees C. These findings would enable the doughnutlike yolk-shell design to be broadly applied for developing other emerging high-performance materials and their secondary batteries.

Automated summary

The study introduces a unique doughnutlike graphene quantum dot (GQD)/Fe2O3@S@SnO2 composite for high-performance Li-S batteries. The composite enhances sulfur utilization and energy storage performance, displaying promising capacity, efficiency, and rate performance. These findings suggest potential for developing other high-performance materials and their secondary batteries.