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The practical use of lithium–sulfur (Li–S) batteries is largely hindered by their poor cycling stability because of the shuttling of soluble lithium polysulfides (LiPSs) in a slow redox reaction. Physical and chemical confinement by carbon or noncarbon hosts has been used to block LiPS shuttling, but this may only be a complete solution to the problem if it combines with LiPS fast conversion into an insoluble sulfide. Here we report a twinborn TiO2–TiN heterostructure that combines the merits of highly adsorptive TiO2 with conducting TiN and achieves smooth trapping–diffusion–conversion of LiPSs across the interface. TiO2 has high adsorption for LiPSs while TiN promotes their conversion into insoluble Li2S. The fast diffusion of LiPSs from TiO2 to TiN helps achieve both high trapping efficiency and fast conversion. By loading such a heterostructure onto graphene, which acts as a physical barrier, a compact and thin …