Engineering tin dioxide quantum dots-coated iron oxide nanorods as sulfur host for polysulfides-immobile lithium-sulfur battery

Quantum dots (QDs) commonly have high activity and strong adsorption capability, making them to be quite promising for energy-storage systems. Here, we develop a SnO 2 QDs-coated rice-shaped Fe 2 O 3 nanorod as a high-performance sulfur host for lithium-sulfur (Li-S) batteries. Small size of SnO 2 QDs and polar Fe 2 O 3 reduce the loss of polysulfides and thereby suppress shuttle effect efficiently, which is verified by density functional theory (DFT) investigations on adsorption energies. The Fe 2 O 3 /SnO 2 QDs@S cathode displays a high Coulombic efficiency of 97.4 % after 100 cycles along with a stable capacity of 475 mAh g –1 . Investigations on rate-performance indicate that the capacity of Fe 2 O 3 /SnO 2 QDs@S cathode is able to recover to the initial values even after three rounds of repeated measurements, showing a good reversibility. It is expected that the stable capacity and Coulombic efficiency during charge-discharge at different conditions, and the strategy of coating QDs on nanorods would find general applications for developing QDs-enhanced energy-storage systems.