A Collaboratively Polar-Conductive Interface for Accelerating Polysulfides Redox Conversion.

In order to alleviate the inferior cycle stability of sulfur cathode, a self-assembled SnO2-doped manganese silicate nanobubbles (SMN) is designed as sulfur/polysulfides host to immobilize the intermediate Li2Sx, and nitrogen-doped carbon (N-C) is coated on SMN (SMN@C). The exquisite N-C conductive network could not only provides sufficient free space for the volume expansion during the phase transition of solid sulfur into lithium sulfide, but also reduces Rct of SMN. During cycling, the soluble polysulfide could be fastened by the silicate with oxygen-rich functional group and hetero nitrogen atoms through chemical bonding, enabling a confined shuttle effect. The synergistic effect between N-C and SMN could also effectively facilitate the interconversion between lithium polysulfides and Li2S, reducing the potential barrier and accelerating the redox kinetics. With an areal sulfur loading of 2 mg/cm2, the S-SMN@C cathodes demonstrate a high initial capacity of 1204 mAh/g, i.e., 72% sulfur utilization at 0.1 C and an outstanding cycle stability with a capacity fade rate of 0.028%, ranging from 2nd cycle to 1000th cycle at 2 C.