Interfacial assembly of CeO nanocrystals into cobalt nitride for synergistic promotion of polysulfide conversion and stable lithium deposition in Li-S batteries.

Lithium-sulfur batteries (LSBs), as the promising next-generation energy storage devices, have attracted great research interests owing to their outstanding theoretical energy density, abundant reserves of sulfur and environmental friendliness. However, the commercial application of lithium-sulfur batteries still faces many challenges such as the heavy shuttle effect of polysulfides and lithium dendrite growth. In this work, CoN@CeO heterostructures were successfully prepared through interfacial assembly of CeO nanocrystals into cobalt nitride from a hydrothermal-nitriding process. The CoN@CeO heterostructure exhibits excellent adsorption-catalytic properties and effectively immobilizes soluble LiPS and promotes its electrochemical conversion. When CoN@CeO was used to modify commercial polypropylene (PP) separators, the results indicated that the LSBs still delivers a high discharge specific capacity of 621.86 mAh g after 600 cycles at 0.5C with low capacity decay rate of only 0.066 % per cycle. Meanwhile, the CoN@CeO also exhibited a high cell capacity after 250 cycles at a high sulfur loading of 4.352 mg. In addition, it also presents excellent resistance to self-discharge. The capacity retention rate was as high as 99.04 % after 72 h resting. The preparation of CoN@CeO heterostructure pave a bright way for the construction of high-performance LSBs through separator modification.