Oxygen vacancies engineering in hollow and porous MnCo2O4 nanoflowers-coated separators for advanced Li-S batteries

A synergistic adsorption-catalysis functional layer consisting of hollow and porous MnCo2O4 nanoflowers with abundant oxygen vacancies is coated on commercial separators for durable high-performance lithium-sulfur batteries (LSBs). Benefiting from well-abundant oxygen vacancies (Vo) formed at low temperatures, the modified separators exhibit excellent catalytic conversion activity towards lithium polysulfides (LiPS) and prevent LiPS from accumulating on the separator surface. And the Vo in MnCo2O4 with spinel-type structure alters the chemical interactions between MnCo2O4 and LiPS, achieving excellent immobilization towards LiPS. Meanwhile, the hierarchical nanostructures offer numerous spaces for insoluble LiPS deposition, thus ensuring sufficient channels for fast lithium-ions (Li+) transfer. As a result, the batteries assembled with the modified separators present a high initial discharge capacity of 1089 mAh g(-1) at 0.5 C with the capacity retention of 83.7% after 200 cycles and outstanding long cycle stability with an ultra-low decay rate of 0.067% each cycle at 2 C. Therefore, such an appealing strategy, combining hierarchical nanostructures with oxygen vacancies engineering in the modified separators, provides a new idea to rationally devise durable and efficient LSBs.