Superior cycling life of Li–S batteries with high sulfur loading enabled by a bifunctional layered-MoO₃ cathode

The shuttle effect is a critical issue that prevents practical applications of high-energy-density lithium-sulfur batteries. Here, a bifunctional positive electrode formed by growing layered molybdenum trioxide nanoflakes onto carbon paper is developed to address this issue, which exhibits not only strong binding ability to anchor polysulfides, but also efficient catalytic activity towards polysulfides redox reactions. As a result, the electrode developed in this work enables a lithium-sulfur battery to achieve an initial capacity of 1145 mAh g⁻¹ and a retention capacity of as high as 976 mAh g⁻¹ after 1000 cycles with a high coulombic efficiency of 99.54% at 1 C. By contrast, the battery with the pristine carbon paper electrode suffers from a severe capacity decay from the 1st cycle (655 mAh g⁻¹) to the 1000th cycle (256 mAh g⁻¹) with a low coulombic efficiency of 89.4%. More strikingly, even with a higher sulfur loading of 8 mg cm⁻², the lithium-sulfur battery with the molybdenum trioxide nanoflakes decorated carbon paper electrode still retains a high specific capacity of 581 mAh g⁻¹ after 1000 cycles. These great improvements reveal that molybdenum trioxide is a promising electrode material to realize the practical application of lithium-sulfur batteries.