Engineering Graphene Quantum Dot-Enhanced Hollow ZnO/ZnCo ₂ O ₄ Nanocubes with Double Shields for Suppressing the Shuttle Effect in Lithium–Sulfur Batteries

The shuttle effect of polysulfides is one of the most severe issues in lithium–sulfur (Li–S) batteries. Here, we develop a graphene quantum dot (GQD)-decorated hollow porous ZnO/ZnCo2O4 as a sulfur host, which effectively immobilizes polysulfides and thus achieves good electrochemical performances. Polar ZnO and ZnCo2O4 as double shields show strong adsorption toward polysulfides as demonstrated by using density functional theory calculations, GQDs in shells improve conductivity, and a hollow porous morphology accommodates volume changes of sulfur upon cycling. The ZnO/ZnCo2O4/GQDs@S cathode displays high performances including a stable capacity of 797 mAh g–1 after 200 cycles at 0.2 C, reversible rate performance after three rounds of measurements, and good tolerance under low and high temperatures. These findings will find important applications for engineering many high-performance materials for Li–S batteries and accelerating applications.