Freestanding sandwich-like hierarchically TiS2–TiO2/Mxene bi-functional interlayer for stable Li–S batteries

Lithium-sulfur battery (LSB) is considered a kind of potential energy storage systems on account of its high theoretical capacity (1675 mAh·g−1) and energy density (2500 Wh·Kg−1). However, poor ionic/electronic conductivity and annoying shuttle effects still need to be resolved. Here a highly flexible and highly conductive MXene (Ti3C2Tx) interlayer with a sandwich structure is reported, the surface of which is a TiS2/TiO2 heterostructure formed by vulcanized. In this framework, the role of TiO2 nanoparticles is adsorbent to combine the lithium polysulfides (LiPSs), and the TiS2 nanoparticles function as catalysts to further facilitate the conversion of long-chain LiPSs to short-chain Li2S2/Li2S under the high conductivity of Ti3C2Tx. Furthermore, the interlayer can protect the Lithium metal anode by preventing polysulfide from depositing on the anode surface. Accordingly, the TOS/MX/TOS interlayer exhibits excellent performance with stable long-term cycling (≈76.1% capacity retention with a decay rate of 0.048% per cycle after 500 cycles at 1C). This sandwiched interlayer with high discharge capacity and steady cycling performances is conducive to the practical application of lithium-sulfur batteries.