Lithium–sulfur batteries hold great promise for next-generation energy storage. But they suffer from rapid capacity decay. The chemical interactions between the sulfur host and polysulfides in these batteries are also poorly understood at the atomic level, impeding improvements in battery performance. Recently, a team led by Shizhang Qiao from the University of Adelaide and Haihui Wang at South China University of Technology, China, reported the fabrication of a novel 2D MoN–VN heterostructure as a model sulfur host in lithium–sulfur batteries with improved capacity decay characteristics (Ye C., Jiao Y., Jin H., Slattery A.D., Davey K., Wang H., Qiao S.-Z. Angew. Chem. Int. Ed. 2018, https://doi.org/10.1002/anie.201810579). The researchers used calculations to show that the electronic structure of MoN can be tailored by incorporating vanadium, leading to enhanced polysulfide adsorption compared with 2D single-component MoN. Furthermore, they used in situ synchrotron X-ray diffraction and electrochemical measurements to reveal efficient regulation and utilisation of the polysulfides in the MoN–VN heterostructure. The MoN–VN-based lithium–sulfur battery had a slow capacity decay of 0.068% per cycle over 500 cycles. This research provides insight into the mechanism of polysulfide adsorption in a heterostructured sulfur-host material and is expected to stimulate further development of hybrid materials for energy storage.