Dynamic Intercalation-Conversion Site Supported Ultrathin 2D Mesoporous SnO 2 /SnSe 2 Hybrid as Bifunctional Polysulfide Immobilizer and Lithium Regulator for Lithium-Sulfur Chemistry.

The practical application of lithium-sulfur batteries is impeded by the polysulfide shuttling and interfacial instability of the metallic lithium anode. In this work, a twinborn ultrathin two-dimensional graphene-based mesoporous SnO 2 /SnSe 2 hybrid (denoted as G-mSnO 2 /SnSe 2 ) is constructed as a polysulfide immobilizer and lithium regulator for Li-S chemistry. The as-designed G-mSnO 2 /SnSe 2 hybrid possesses high conductivity, strong chemical affinity (SnO 2 ), and a dynamic intercalation-conversion site (Li x SnSe 2 ), inhibits shuttle behavior, provides rapid Li-intercalative transport kinetics, accelerates LiPS conversion, and decreases the decomposition energy barrier for Li 2 S, which is evidenced by the ex situ XAS spectra, in situ Raman, in situ XRD, and DFT calculations. Moreover, the mesoporous G-mSnO 2 /SnSe 2 with lithiophilic characteristics enables homogeneous Li-ion deposition and inhibits Li dendrite growth. Therefore, Li-S batteries with a G-mSnO 2 /SnSe 2 separator achieve a favorable electrochemical performance, including high sulfur utilization (1544 mAh g -1 at 0.2 C), high-rate capability (794 mAh g -1 at 8 C), and long cycle life (extremely low attenuation rate of 0.0144% each cycle at 5 C over 2000 cycles). Encouragingly, a 1.6 g S/Ah-level pouch cell realizes a high energy density of up to 359 Wh kg -1 under a lean E/S usage of 3.0 μL mg -1 . This work sheds light on the design roadmap for tackling S-cathode and Li-anode challenges simultaneously toward long-durability Li-S chemistry.