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

Abstract

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 ≈100% Coulombic efficiency, and a recoverable rate performance after repeated measurements. The constructed battery possesses a good tolerance at a high temperature of 45 °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.